View Full Version : DIY FB1i anyone?


mikesnowdon
24-06-08, 04:05 AM
Im new to this so I apologise in advance for asking silly questions.

Im currently working on the cabinet dims for the FB1. I have the external dims which can be downloaded from the pmc website. Ive managed to cut and paste the 'cut away' image of the FB1 (showing the TL and damping) onto the drawing with the external dims. Now all I need to do is find out what thickness the panels are and I'll be able to work out the rest of the dims. (A freind is a CAD expert so he will help me here) Does anyone know the cabinet wall thickness? (below is an example based on the OB1)

http://a637.ac-images.myspacecdn.com/images01/51/l_c04433b5f9f0a8a2fd353f6347085934.jpg


Next question is of course on the xo. Ive been searching and searching for a schematic of some sort but nothing yet. Ideally I'd like the latest 'i' version but the '+' would suffice. Anyone here own FB1's or know the xo setup? (I found this website who sell the crossovers, pricey though: http://www.technosound.co.uk/nav.php?pageid=SpeakerSpares#PMC)

This leads to the final question: Drivers.

From what I can tell the midbass is either:

Vifa M17WG-09-08 or Vifa M17WH-09-08

The tweeter I believe is:

Vifa D27TG-45-06 for the '+' version.

For the 'i' version:

[The PMC website tells us the tweeter is a 27mm SONOLEX* unit (*which I've found out is a trademark of SEAS). The unit PMC use also has a rear chamber.]

Having looked at the SEAS website I've been able to narrow it down to this:

H0881-06 27TFFC.

Can anyone help with corect driver identification or crossover details please?

Thanks in advance for your help and advice.

Mike

PigletsDad
24-06-08, 04:43 AM
SEAS and Tymphany (Vifa is one their brands) are both set up to do special OEM versions of drivers for manufacturers, so there is every chance that they are special versions tweaked to specifications that PMC set.

As such, they are probably only available from PMC. If you use off the shelf drivers, the crossover will need to be redesigned to suit the devices you can buy; this needs measurement kit, software and some expertise.

You are probably much safer working with a design for which the drivers are known and available. Here are two sites that offer lots and lots of designs, most of which are based round drivers that are available for DIY.

http://www.zaphaudio.com/
http://www.troelsgravesen.dk/Diy_Loudspeaker_Projects.htm

mikesnowdon
24-06-08, 05:01 AM
Thanks for the advice and the links, both sites that I visit regularly.

Your right about the drivers probably being tweaked versions, the faceplate of the tweeter is certainly a PMC only thing (whether it does anything or is just a gimmick is questionable). Then again they might br so simmilar to the OEM units that this project would be possible. If it were the case then I would only need one crossover which I would copy, exactly using the same components, so I have a pair.

Niel @ Wilmslow audio has told me that the midbass is almost certainly a Vifa M17WG-09-08. I think I'll bite the bullit and assume the tweeter I have chosen is the correct one. If at the end of the day it dosent sound right I can always get Wilmslow to do some measurements for me and tweak the xo hf section accordingly.

Is there anybody out there who owns FB1's and wouldnt mind removing the drivers and passing on the part numbers?

Mike

James Evans
24-06-08, 05:57 AM
buy some of these for just over 200 and pull them apart...

http://www.ornec.com/Von_Masoch_FB1_Standing_Speakers_QQC100110B

mikesnowdon
24-06-08, 06:11 AM
Thats unbelievable, they look identical! Had a look at the Ornec website and they also have a Proac 2.5 lookalike? Who are these guys?

James Evans
24-06-08, 06:15 AM
There's threads on various fora discussing these and the manufacturers are aware. Those FB1alikes had gone from the site until recently, only the tb2alikes were there last time I looked.

PigletsDad
24-06-08, 06:41 AM
Unhelpful post removed.

mikesnowdon
24-06-08, 07:03 AM
Removed.

colasblue
24-06-08, 02:40 PM
Judging by the number of customer reviews they'll soon be getting into double figure sales when you consider all models together.

I don't think the major brands have much to worry about

be interested to know what they actually sound like though but the prices seem just too cheap to even cover the cost of the drivers!

mikesnowdon
25-06-08, 06:03 AM
The Von Masoch appear to be identical but of course we cant see inside. For all we know they could just be ported? At the end of the day there cheap fakes and the import tax, shipping makes the outlay, ca. 600ish. Its probably cheaper and alot more fun to Do-It-Yourself.

Ideally I'd like to get a few people interested in this. I can do the cabinet plans, we can all chip in and but an buy an actual FB1i crossover to copy. And with a litlle detective work find out the exact tweeter used.

If sucessful a OB1 alike could be developed, perhaps with a better midrange though, SS 12M4631G00 anyone? Sort of 'Ekta' with cheaper woofer, enclosure based on the OB1 TL? http://www.troelsgravesen.dk/Ekta.htm

zener
25-06-08, 06:10 AM
Mike I have FB1's , with the old metal dome tweeter , so not much use for that or the crossover , but the bass/mid is the same as is the cabinet , I can pop the drivers out and measure what panels i can ie. thickness

James Evans
25-06-08, 06:12 AM
Hi Mike. I was thinking about trying to diy my DB1s into DB1is a while ago and looked into the tweeter. I think I came to the same conclusion as you about it being the 27TFFC. It may well be modified to pmc's spec, who knows.... I have no idea on what xover changes would have been required. I think in my case the tweeter is deeper than the one in the original DB1 so it wouldnt have fitted in the cabinet (unless again there's been some pmc specification going on there...)

Anyway, I digress, just wanted to backup your tweeter findings.

Welcome back to the fold btw!

mikesnowdon
25-06-08, 06:18 AM
Zener,

If you could do that it would relly help with the cabinet plans, while you have the midbass out could you take note of the partnumber on the driver please?

James,

Im hoping the only difference with the tweeter is the groves around the faceplate. I think this is supposed to aid dispersion but I cant imagine it effecting the fr too much. Hopefully someone with the 'i' version can help us here.

PigletsDad
25-06-08, 06:31 AM
A site with some useful background on transmission line speakers (and related designs) is Martin King's - http://www.quarter-wave.com/.

I realise that you are primarily trying to clone an existing design, rather than do a new one from scratch, but some of his material, or one of his spreadsheets, may help tweak the design for the differences (if any) between the driver that PMC use and the Vifa M17WG-09-08.

mikesnowdon
25-06-08, 06:38 AM
Good link, thanks.

mikesnowdon
25-06-08, 06:49 AM
Hi Mike. I was thinking about trying to diy my DB1s into DB1is a while ago and looked into the tweeter. I think I came to the same conclusion as you about it being the 27TFFC. It may well be modified to pmc's spec, who knows.... I have no idea on what xover changes would have been required. I think in my case the tweeter is deeper than the one in the original DB1 so it wouldnt have fitted in the cabinet (unless again there's been some pmc specification going on there...)

Anyway, I digress, just wanted to backup your tweeter findings.

Welcome back to the fold btw!

If/When we find out the tweeter and xo changes might be you can carefully rout out the tweeter recess if necessary. If you cant do it yourself, im sure a skilled carpenter could do it for a small fee.

James Evans
25-06-08, 07:00 AM
It's actually the depth chamber as opposed to diameter, or depth of surround - the DB1 transmission line is pretty crammed in and is fairly tight up behind the original tweeter, which isn't as deep as the 27TFFC. I suppose this is where the requirement for pmc to redesign the cabinet came from (possibly...). From memory the diameter and screw hole placement is identical.

Aren't the bass/mid-bass drivers different in the i series as well? Something to do with quality control at vifa going downhill after being bought out - the grey cells may be malfunctioning on that one.

Dick Bowman
25-06-08, 07:36 AM
Can't really see the point in DIY copying. Surely more to be had in getting to understand underlying principles and construction techniques, then trying something original.

As for commercial duplicates where we can only judge the outsides...

mikesnowdon
25-06-08, 07:50 AM
It's actually the depth chamber as opposed to diameter, or depth of surround - the DB1 transmission line is pretty crammed in and is fairly tight up behind the original tweeter, which isn't as deep as the 27TFFC. I suppose this is where the requirement for pmc to redesign the cabinet came from (possibly...). From memory the diameter and screw hole placement is identical.

Aren't the bass/mid-bass drivers different in the i series as well? Something to do with quality control at vifa going downhill after being bought out - the grey cells may be malfunctioning on that one.

There is a simmilar SEAS unit wo rear chamber. Basically the same as 27TFFC but no rear chamber hence reduced depth. Would probably fit. Then you'd need to measure it in the DB1 baffle and tweak the xo accordingly. (If your lucky you might get away with upgrading the Caps and tweaking the resistor value, I did this in my TDL's without measuring and got a definate improvement) I know the midbass used in the OB1i is a Morel unit. I think the rest are still vifa though.

zener
25-06-08, 09:45 AM
OK Mike my FB1's share the same bass / mid unit with the FB1+ , which is a VIFA M17 WG09. The panels are all 3/4" thick MDF type stuff.

James Evans
25-06-08, 09:58 AM
OK Mike my FB1's share the same bass / mid unit with the FB1+ , which is a VIFA M17 WG09. The panels are all 3/4" thick MDF type stuff.

Zener, is the W in there a typo? Was it supposed to be SG09? I can't find any info on a WG09

zener
25-06-08, 10:13 AM
defo WG , wilmslow audio do them for 45 ea. The full no is VIFA M17 WG 09 08.
OK some more info. The top of the transmission line ends 4 and 1/4" from the inside face of top panel and it is 4 and 7/8" from the inside face of the front baffle (Measured to the front top corner of the transmission line)

zener
25-06-08, 11:13 AM
The Panel for the base of the speaker is 5/8" thick and the lower part of the transmission line is as follows. Height above the inside of the base 4 and 1/4" , this is the bit that exits out of the "port". The lower end of the transmission line is also 4" from the inside of the rear panel.
all panels except the base are defo 3/4" thick , including the panel that makes up the line.

James
25-06-08, 11:57 AM
Can't really see the point in DIY copying. Surely more to be had in getting to understand underlying principles and construction techniques, then trying something original.

As for commercial duplicates where we can only judge the outsides...
There was a time the ProAc Response 2.5 was the most copied commercial design in the world. However, I don't think many got close to the original's performance. That said, copying an existing design is a great way to learn about DIY loudspeakers.

James

mikesnowdon
25-06-08, 02:04 PM
Zener, Good man!

We have confirmed the correct midbass and have enough data to know we can get close to duplicating the enclosure. I'll get to work on drawing up cabinet plans soon. I intend to have a panel list also.

Next problem is to solve the crossover. I can buy a FB1i (not sure about FB1+) xo but they want 82 for one. If its not possible to find schematics this might be the only option. If anyone else is interested would they mind chipping in to cover the cost. Once we have one we can draw up a schematic and source the same components to make up as many as we want.

http://www.technosound.co.uk/nav.php?pageid=SpeakerSpares#PMC

(The same company claim to have the 'i' version tweeters, but 102 each is mad)

mikesnowdon
25-06-08, 03:54 PM
Heres the preliminary 'cut and paste' for the FB1'i'. Tomorrow I'll start adding the dimensions given by Zener and begin roughing out other dimensions. Eventually I'll pass it on to my freind the CAD expert to be re-drawn from scratch. This will ensure the dims are correct and enable a drawing to made of each individual panel.

http://a159.ac-images.myspacecdn.com/images01/82/l_df48e7da387ef04d4ec70e30453dcc9e.jpg

PigletsDad
26-06-08, 01:25 AM
A couple of ideas, which you can ignore if they aren't useful - its your project after all.

From skimming the Mike King documents, one of the key things in making/tuning a transmission line is the cross sectional area of the line. If you want or need to change say the panel thickness, increase the depth of the box so as to preserve the free area.

The air flow likes to go smoothly round corners. If you look at some of Troel's designs or some of Eekel's, they put curved sections in where the line doubles back on itself. Without going that far, you could add some stiffness and smooth the flow a bit by putting some triangular section fillets (cut from some triangular section beading or similar) in the front and back top corners, and in the bottom back corner. You could also round the edges on the top of the inner vertical bit of wood.

Dowser
26-06-08, 01:30 AM
Re. smoothing airflow - whenever modifying high performance turbo engines I always pay very close attention to same, it is worth the effort. I always found it easiest to think of water flowing through the space, instead of air, and that there are little fish in the water. You need to design it such that the fish are disturbed as little as possible as they flow through the space.

Richard

mikesnowdon
26-06-08, 01:43 AM
A couple of ideas, which you can ignore if they aren't useful - its your project after all.

From skimming the Mike King documents, one of the key things in making/tuning a transmission line is the cross sectional area of the line. If you want or need to change say the panel thickness, increase the depth of the box so as to preserve the free area.

The air flow likes to go smoothly round corners. If you look at some of Troel's designs or some of Eekel's, they put curved sections in where the line doubles back on itself. Without going that far, you could add some stiffness and smooth the flow a bit by putting some triangular section fillets (cut from some triangular section beading or similar) in the front and back top corners, and in the bottom back corner. You could also round the edges on the top of the inner vertical bit of wood.

Good point to raise. Its tempting to try and improve the FB1 I do agree. My only consideration is that PMC have spent years developing the design of their speakers and I feel that deviating from the design might kill the the PMC'ness (if you know what I mean).

However, you raise a valid point so It's worth considering. Would adding corners reduce the effective area of the line and negate other alterations to the enclosure?

Dowser, nice analogy. How about Glass peakers with fish inside!!!! (Joke):D

PigletsDad
26-06-08, 01:50 AM
GWould adding corners reduce the effective area of the line and negate other alterations to the enclosure?

I think it should be OK if the corner fillets are small enough so that the cross section is never smaller than in the adjoining straight bits of the line. If the baseline of the fillets is less than half the line width, I think this is guaranteed.

In practice, I think the improvement might be biggest for the one near the mouth (bottom back corner), as the air velocity is highest there.

Also, the top front corner is pretty constrained by the tweeter cutout, so you probably can't do a lot there.

James Evans
26-06-08, 01:50 AM
a quick look around at pricing - you're looking at about 170-180 ish for the drivers (not delivered), prob 50 or so for the crossover parts depending on what caps you go for, then there's the wood, foam, spikes and any tools you need to buy. Certainly an investment! I know the challenge is the main thing, but it's not something to take on lightly given there's no guarantees. (ever the pessimist me, just ask my mates)

mikesnowdon
26-06-08, 02:04 AM
Thanks James.

PD,

Troels has a TQWT design where hes added corner angles behind the Tweeter, it can be done and Im definately considering it. Thanks.

http://www.troelsgravesen.dk/JA8008.htm

PigletsDad
26-06-08, 02:51 AM
I see like http://www.troelsgravesen.dk/JA8008_files/Ja8008_cabs_06.jpg

Looks scary for the router challenged!

mikesnowdon
26-06-08, 04:26 AM
Having looked at this design on Troels's website am I right that the FBI is actually a TQWT variant rather than a traditional T Line?

Pete MB&D
26-06-08, 04:37 AM
Hi, Pigletsdad

Hand plane and coping saw 5 min job, it dosn't have to scream to cut wood.;)

Pete

PigletsDad
26-06-08, 05:43 AM
Having looked at this design on Troels's website am I right that the FBI is actually a TQWT variant rather than a traditional T Line?

Mike King points out that there is a whole family of related designs, all based on long pipes that are tuned to resonate at or near the driver resonance, but with differing tapers. A TQWT is thin at the closed end, in fact tapers to a point, and widens to a maximum size at the open end. The FB1 looks like it is wider at the closed end, and gets slightly smaller towards the port, so I think it more or less belongs in the T-line side of the house.

From a certain point of view a reflex cabinet can be thought of as an extreme member of the same family, where the pipe length is no longer what sets the resonance, but rather the box volume and port inertance.

00940
29-06-08, 05:45 AM
A site with some useful background on transmission line speakers (and related designs) is Martin King's - http://www.quarter-wave.com/.

I realise that you are primarily trying to clone an existing design, rather than do a new one from scratch, but some of his material, or one of his spreadsheets, may help tweak the design for the differences (if any) between the driver that PMC use and the Vifa M17WG-09-08.

I strongly support PigletsDad here. Even if you copy (or try to copy) an existing design, the 25$ Martin King asks for a mathcad model are a bargain. It could save you a lot of time optimizing your design, especially for the damping material.

I certainly was extremely happy with the results I got, using the P17WJ and D26TG: http://www.diyaudio.com/forums/showthread.php?s=&threadid=85736

mikesnowdon
29-06-08, 05:30 PM
Heres the preliminary 'cut and paste' for the FB1'i'. Tomorrow I'll start adding the dimensions given by Zener and begin roughing out other dimensions. Eventually I'll pass it on to my freind the CAD expert to be re-drawn from scratch. This will ensure the dims are correct and enable a drawing to made of each individual panel.

http://a159.ac-images.myspacecdn.com/images01/82/l_df48e7da387ef04d4ec70e30453dcc9e.jpg

Sorry I havent done this yet. The new arrival to our family and busy shedule have kept me rather busy. I'll try and get started this week and hope to at least have Zener's data included so I can confirm If I've duplicated his measurements correctly.

By the way, I won a pair of Vifa M17WH-09-08, placed bid before this thread began, pissed that theyre not the right drivers! Still, it will be fun to play with them so Im going to try them in my TDL's and see how they perform. Wilmslow audio reccomend the M17WG's as a direct replacement for the RTL2 midbass, without the need to tweak the crossover......?

Hope you all had a nice weekend. :)

mikesnowdon
02-07-08, 03:20 PM
I strongly support PigletsDad here. Even if you copy (or try to copy) an existing design, the 25$ Martin King asks for a mathcad model are a bargain. It could save you a lot of time optimizing your design, especially for the damping material.

I certainly was extremely happy with the results I got, using the P17WJ and D26TG: http://www.diyaudio.com/forums/showthread.php?s=&threadid=85736

Id like him to take a look at this, how do I contact him?

PigletsDad
03-07-08, 02:18 AM
Id like him to take a look at this, how do I contact him?

I don't think you do, he has downloadable software (Mathcad workbooks) that he sells that contain all his formulas and design tools.

Also, he has published lots of documents with useful stuff, and these are available without charge.

mikesnowdon
03-07-08, 04:16 AM
I don't think you do, he has downloadable software (Mathcad workbooks) that he sells that contain all his formulas and design tools.

Also, he has published lots of documents with useful stuff, and these are available without charge.

Thats great. I have no idea what a Mathcad work book is though (I know what auto cad is)! Can anyone enlighten me?

Cheers, Mike

Sparts155
03-07-08, 04:26 AM
Congratulations on the new arrival Mike! One good thing with tall speakers is that the drivers will be out of reach of questing little fingers ..... at least for a while!

Dan

mikesnowdon
03-07-08, 04:29 AM
The M17WH-09-08 have pros and cons in my RTL's. Midrange is too forward and bass level is too low, although it is nice bass. I like the sound of them and I reckon in the right box and on a carefully designed xo they could sound really good. Anyway, I'll be selling them on, or swapping for a pair of WG's if I can.

PigletsDad
03-07-08, 05:23 AM
Thats great. I have no idea what a Mathcad work book is though (I know what auto cad is)! Can anyone enlighten me?

Cheers, Mike

It is a bit like a spreadsheet on steroids; you type a few numbers about your driver and box in, and masses of calculations happen, graphs are drawn and so on.

Mathcad is a mathematics and graphing package. A workbook is file for Mathcad with some calculations and so in it.

There is a free viewer for the workbooks that MJK links to, which lets you use his design tools, but wouldn't allow you to develop new workbooks.

mikesnowdon
03-07-08, 06:25 AM
Sounds good.

My freind is drawing up the Cabinet plans as I write this. It should be ready by tomorrow. I will have individual drawings of each panel also. If anyone is interested dont hesitate to PM me your email address.

Mike

mikesnowdon
03-07-08, 01:44 PM
Congratulations on the new arrival Mike! One good thing with tall speakers is that the drivers will be out of reach of questing little fingers ..... at least for a while!

Dan

Thanks Dan.

Im thinking of having wire mesh behind the grille cloth and maybe attatching the grille with some nice brass 'top hat' nuts (I might have some 'thumbwheel' type screws made up, or use brass allen heads, epos style). That way it will add a nice aesthetic feature and keep the drivers protected. Of course its not ideal for sound but it shouldnt effect it too much, and I can take them off when the nippers in bed.

Need to find out about crossovers now, its probably wise to have one designed from scratch, that leaves tweeter options open, and the possibility of asymetrical placement. Audio-conponents.co.uk have a measurement service which is well priced, and thye're not that far from me so I'll probably do that. Of course there might allready be some proven crossovers out there based on the Vifa midbass and a simmilar baffle profile. If anyone knows, please let me know.

Thanks for reading,

Mike

James
03-07-08, 06:19 PM
Mike,

Madisound offers a crossover-designing service, which is based on data they have collected from drivers they sell. Just tell them the dimensions of your cabs, and the drivers you intend to use, and they can put a design together for you. That would be cheaper and less frustrating than taking measurements separately from the designing.

James

mikesnowdon
04-07-08, 05:21 AM
Mike,

Madisound offers a crossover-designing service, which is based on data they have collected from drivers they sell. Just tell them the dimensions of your cabs, and the drivers you intend to use, and they can put a design together for you. That would be cheaper and less frustrating than taking measurements separately from the designing.

James


Sound like a good soloution, thanks. I guess it would make sense to have a working crossover to start with, then I can make small tweaks to fine tune it if necessary.

hi fi fo fum
04-07-08, 07:32 AM
I'd just try a 1.2 to 1.5 mH coil 18 g on the woofer see how it sound 18 to20 uf cap with a 6.8 ohm resister across the pos and neg of the woofer.

Steve
PS no computer was used to model this.

And I may even work my way down to a smaller coil .7mH on the woofer

Wilky
04-07-08, 07:54 AM
I'd just try a 1.2 to 1.5 mH coil 18 g on the woofer see how it sound 18 to20 uf cap with a 6.8 ohm resister across the pos and neg of the woofer.

Steve
PS no computer was used to model this.

And I may even work my way down to a smaller coil .7mH on the woofer

Steve.

I think you meant tweeter, didn't you?

Dave.

hi fi fo fum
04-07-08, 07:58 AM
No ...Coil in line with the pos of woofer /cap and resistor across pos and ground of the woofer... (impedance correction) but you might not need it with this type of enclosure

Wilky
04-07-08, 08:15 AM
Sorry, got you .... just wondered where the HF filter components were?
Would that be part of a second order network like this?

http://www.ajdesigner.com/crossover/crossoversecond.php

hi fi fo fum
04-07-08, 09:05 AM
I'd go for the tweeter 5.6 uf----------5.6uf
I
I
.2mh
I
I

hi fi fo fum
04-07-08, 09:08 AM
slide the "I"'s over so they are between the two 5.6uf caps and then you can attenuate the tweeter level to taste.

mikesnowdon
07-07-08, 06:25 AM
Drawings available now.

Cross section and individual panels available.

Please pm me if you interested, I will send to your email.

Mike


http://a331.ac-images.myspacecdn.com/images01/103/l_4df910c51e95b8f55b75f1902992bfea.jpg

hi fi fo fum
08-07-08, 08:04 AM
Thanks Mike.

Steve

mikesnowdon
08-07-08, 08:13 AM
Thanks Mike.

Steve

No problem.

What do you think then?

James
08-07-08, 11:37 AM
Mike,

Textbook XO formulas don't work in the real work. Save yourself time and the cost of parts, and get the XO designed for you by Madisound.

James

mikesnowdon
08-07-08, 02:08 PM
I think I might have got lucky with a pair of blown FB1+ crossovers. Im not sure exactly the damage but I suspect its just blown resistors. If I cant repair then at least I can copy the circuit and build new ones. (the guys daughter had a party and overdid it a little with dads system)

I dont have them yet, the guy is waiting for replacements to arrive. Fingers crosse he dosent forget me!

hi fi fo fum
08-07-08, 02:10 PM
No problem.

What do you think then?

I'll give them a go, but I don't know why they short the TL the way they do.
TL are not an exact science .......

Steve

hi fi fo fum
08-07-08, 02:12 PM
Mike,

Textbook XO formulas don't work in the real work. Save yourself time and the cost of parts, and get the XO designed for you by Madisound.

James

Hi James ,very true..... what does Madisound use?

James
08-07-08, 03:40 PM
They use LEAP. Read all about their service here (http://www.madisound.com/services/leap.php). Of course, it'd better to have your own CAD system and DIY properly - but the Madisound service is a cost-effective alternative.

James

hi fi fo fum
08-07-08, 06:31 PM
Ah, I still prefer the old fashion way......

James
08-07-08, 06:57 PM
Each to their own ...

mikesnowdon
11-07-08, 08:01 AM
I found out PMC do a 'i' version upgrade kit, comprising new crossover and tweeter. Im going to find out how much they cost. If its a good price then all I need is a pair of woofers and 2 kits and Im all set!

James Evans
11-07-08, 08:07 AM
Mike, do pmc let you buy the kit now? When I asked about upgrading my db1s to + they said it had to be factory or dealer done, and cost roughly 300

mikesnowdon
11-07-08, 01:05 PM
Mike, do pmc let you buy the kit now? When I asked about upgrading my db1s to + they said it had to be factory or dealer done, and cost roughly 300


I spoke to PMC today and they quoted me 250ish for a pair of '+' kits. They dont do a 'I' upgrade kit and wouldnt tell me why, when I asked the guy said "ERRRRRR", bullshit, he knows why! (they probably want you to buy new speakers!). When I asked about purchasing a pair they told me I'd have to go though a dealer, so I asked for a local dealer and got a number. I called the dealer and they tried to tell me I had to have them installed for me, I explained that its not difficult to change a tweeter and wire in a new crossover and that I was only interested in buying the kits. I was then told that I would have to wait while the guy called PMC to "check". He didnt get back to me yet. I asked if I'd need serial numbers of my standard PMC speakers (LOL!) and he said he thinks theres no need. I guess PMC are aware of the cloning that goes on and are trying to ensure people dont do exactly what Im attempting! Maybe theyre reading this as I type!!!! (I shouldnt have given my name, doh!!) Now im paranoid:(

He might call back on Monday, fingers crossed.:);)

hi fi fo fum
21-07-08, 01:40 PM
How are they coming along ?????

Steve

mikesnowdon
21-07-08, 02:18 PM
How are they coming along ?????

Steve

Nothing yet, funds are tight and I have a couple of other projects in the pipeline. Im still waiting for a quote from Wilmslow for the cut panels. Good news is that FB1+ upgrade kits are available (ca. 250) so all you need is Vifa midbass, some egg crate foam and a couple of sheets of MDF.

I hope to get started soon, I realize its probably cheaper to have the front baffle made for me and do the rest myself. I'll probably be getting a circ saw and a decent guiderail at the end of the month.

Zener,

Any chance of a shema of your crossover? Its know its not the + or i version but its a starting point, and cheaper than buying a + upgrade kit.

mikesnowdon
09-09-08, 11:28 AM
Hi everyone!

I just got back from Latvia and found a nice package had arrived....

PMC FB1+ crossovers!!! Ok, theyre a bit kanckered, I was lucky enough to find - while googling - a thread on AVforums where a guy had suffered hi-fi sabotsage at the hands of his daughter. She'd thrown a party while Dad was away and managed to fry his crossovers. I asked if he wouldnt mind sending me the busted networks and here they are.

At first glance it I can see 3 resistors that are fried and it looks like the HF caps are cooked too. Fortunately the markings are still readable on the caps and resistors. I'll de-solder the components soon and have a look at the PCB, seems ok though, just a little scorched. Big respect to PMC for using Solen MKP's on the HF section. Will post some pics soon.

mikesnowdon
10-09-08, 01:03 PM
Right here are the pics of the crossovers. As we can see it appears that just 3 resistors and 2 caps need replacing.

http://a876.ac-images.myspacecdn.com/images01/1/l_76bad8436bbd1777e92384111530fa43.jpg

The PCB is dual sided and looks to be ok. The underside of the crossover with the worst damage is a little cracked, but I cant actually get to it it without de-soldering first. The problem is that there's alot of hot glue in the way. A freind once suggested freezing it with freeze spray or something, this makes it brittle so it can then be chipped off, apparently. Anyone tried this or is there a better way to remove it?

Anyway, at the very least I have a circuit to copy and all the neccesarry values are shown clearly in the photo below.

http://a114.ac-images.myspacecdn.com/images01/87/l_9bc0b6a9dd87508d930ddf79590ab6d9.jpg

One other thing I've noticed is that the coils look a bit messy. I'd expect perfect and neat windings in a speaker costing over a 1K. Is this a problem? Should I remove them and tidy them up?

Many thanks to Glenn of AVforums for kindly donating these crossovers. Top bloke.

hi fi fo fum
10-09-08, 03:42 PM
looks like warranty repair to me :):):):)
I love seeing stuff like this you know it must of been a ROCKING party for a while !!!!!!!

PigletsDad
11-09-08, 02:04 AM
OK, lets list the component values that are clear.

Electrolytic cap 20uF, 100V - should be OK, but replace to be safe.
Poly cap 3.3uF, 400V - I'm sure this will be fine.

All resistors 7W.
2.7 Ohm - both look OK, but probably replace to be safe.
6.8 Ohm - both sad
56 Ohm - one sad, one visually OK. Replace both to be on the safe side.

Two ferrite cored inductors. These are not marked in value, and probably the easiest thing is just to recycle them. I don't think minor unbundling of the last turn of wire is either here or there.

To damage a 56Ohm 7W resistor they must have had some real stick - the main drivers must have been absorbing well over 50W average for some time!

mikesnowdon
11-09-08, 02:26 AM
Thanks PD.

Yeah, apparetly one of the woofers suffered a blown voicecoil!

Im not sure the Solen caps are ok, they look like they've suffered heat damage but it could be that just the outer plastic has melted and internally theyre fine?

How about removing hot glue then? Any suggestions?

James Evans
11-09-08, 02:45 AM
When I took the same parts off my DB1 xovers I used a sharp modelling knife to slowly cut under the hot glue, and once I had leverage prised the parts off - no pcb damage.

There's no doubt better ways of going about it!

PigletsDad
11-09-08, 04:52 AM
Im not sure the Solen caps are ok, they look like they've suffered heat damage but it could be that just the outer plastic has melted and internally theyre fine?

I think the Solens have got some smoke on them from the burning resistors, but have no idea if they are effected inside. At a minimum, check with a DVM that they are not short circuited; if not there is a good chance that they are OK.

mikesnowdon
11-09-08, 05:05 AM
If im replacing resistors then I might as well upgrade them too, any suggestions?

hi fi fo fum
11-09-08, 05:20 AM
Mudorf

James Evans
11-09-08, 05:57 AM
Depends if you're keeping the pcb, or going to do a separate external hardwired XO, which is probably what I'd do in this case. Then you're not tied by cap size and can experiment. My DB1s had a 10uf electrolytic where you have a 20uf and a bennic PP cap on the tweeter. The pcb looks identical. The pcb had just enough space to fit a 10uf bennic PP, but they are pretty small compared to other PP caps. I bought my mills resistors and PP caps from partsconnexion - take a look at their site/prices and make a judgement call on the caps. Solen are pretty cheap so may be a good starting point, with a view to trying out other caps in the future.

PigletsDad
11-09-08, 05:59 AM
Another source for crossover caps and parts is Wilmslow (despite the appalling site).

I would second JE's suggestion of rebuilding hardwired, rather than trying to salvage the PCB.

James Evans
11-09-08, 06:04 AM
I'd also say I'm sure if I really noticed any change swapping the resistors to mills, so you may want to try "bog-standard" cheaper resistors first. Have you got the drivers yet? (I'd be interested to know the part number of the tweeter...)

fatmarley
11-09-08, 06:13 AM
Mike,
That crossover was a great find! I didn't think you'd find one in a million years.

Mundorf and Mills resistors can be bought from www.hificollective.co.uk

mikesnowdon
11-09-08, 06:57 AM
I'd also say I'm sure if I really noticed any change swapping the resistors to mills, so you may want to try "bog-standard" cheaper resistors first. Have you got the drivers yet? (I'd be interested to know the part number of the tweeter...)

I think its a Vifa D27 in the '+' version?

Another source for crossover caps and parts is Wilmslow (despite the appalling site).

I would second JE's suggestion of rebuilding hardwired, rather than trying to salvage the PCB.

Im fammiliar with Wilmslow, agreed about their site....

Im considering salvaging the PCB to be honest. What im considering is using a resin compound to fill in the space between the PCB and terminal plate. I saw something simmilar on Jhon Eekels site I think? Obviously I wouldnt do this until any necessary tweaking was complete.

mikesnowdon
13-09-08, 08:38 AM
Mike,
That crossover was a great find! I didn't think you'd find one in a million years.

Mundorf and Mills resistors can be bought from www.hificollective.co.uk

Cheers Matt. I was really lucky there.

Just need to buy drivers and build cabs now (and repair the networks).

I think I'll have the front baffles made by wilmslow (Who else does bespoke cabinets by the way?) and build the rest myself. Should be pretty easy to do.

Are PMC using a 'special' damping material?

http://a980.ac-images.myspacecdn.com/images01/92/m_d7299841b2c41ebe2cd0ebb89fee52b3.jpg

mikesnowdon
13-09-08, 11:04 AM
Anyone know what it is?

mikesnowdon
16-09-08, 02:15 PM
Stripped down the crossover with the worst damage to inspect....

Bad news is that one of the traces is broken (but easily repaired if I choose to). Good news is the Coils are marked with their values which means brand new crossovers could be built with sexy Coils.

Here are some pics:

http://a289.ac-images.myspacecdn.com/images01/73/l_d071d6747b94f0034265825f471a9f88.jpg
http://a461.ac-images.myspacecdn.com/images01/107/l_b1daf839c3717c8e333445c04a52574c.jpg
http://a431.ac-images.myspacecdn.com/images01/50/l_ff95a12e8b6ef96095417c7af685bae6.jpg
http://a396.ac-images.myspacecdn.com/images01/6/l_e8aa4334afaff53842b7ba861a47fe9b.jpg

mikesnowdon
16-09-08, 02:18 PM
In the photos above the coil on the left is marked 1.2, on the right one is marked 0.9.

Is there anyone out there skilled enough to draw up a schematic for me using the above photos? All the values should be visible from the earlier pictures.

By the way, the solen cap was defo fried, had a large hole in it.

James Evans
17-09-08, 02:59 AM
In the photos above the coil on the left is marked 1.2, on the right one is marked 0.9.

Is there anyone out there skilled enough to draw up a schematic for me using the above photos? All the values should be visible from the earlier pictures.

By the way, the solen cap was defo fried, had a large hole in it.

Mike, based on the above your xover is:

http://www.spev.co.uk/fb1.gif

quickly knocked up in ppt so boxes for inductors rather than coils, but it should be clear hopefully!

Very similar to the DB1 xover unsurprisingly

James Evans
17-09-08, 09:13 AM
if you source that pyramidal foam damping post the link here please! Madisound have the shielded version of the original DB1 drivers on offer at $29 a pop at the moment. I'm quite tempted to knock up a cloned pair with the tweeters I've just taken out of mine.

mikesnowdon
17-09-08, 03:36 PM
if you source that pyramidal foam damping post the link here please! Madisound have the shielded version of the original DB1 drivers on offer at $29 a pop at the moment. I'm quite tempted to knock up a cloned pair with the tweeters I've just taken out of mine.

No worries, will post the link when I find it.

The Db1 cabs should be easy to duplicate. just find a reference point and work at the dims from there.

Thanks for the xover scematic.

James Evans
18-09-08, 01:58 AM
yup, I have all the internal dimensions. The foam is the tricky one - if it can be plain foam and not pyramidal then that makes life easier.

mikesnowdon
18-09-08, 07:18 AM
Do you mean 'pyramidal' aka Dimple foam? If yes then the stuff is readily available. My only consideration would be getting the same density of the foam itself. Need to do some more detective work....

James Evans
18-09-08, 07:47 AM
yeah, as in the foam on this page:

http://www.positive-feedback.com/Issue25/pmc_fb1.htm

to be honest I've not really looked too hard as my cash is committed elsewhere at the moment, but I could throw a diy pair together, with better xover components, for about 150, which is almost cheap enough to have a crack at, as long as I can get someone to cut the wood for me.

mikesnowdon
27-09-08, 02:38 PM
No luck with the damping foam yet. Had a read though and found a few articles claiming that PMC 'have developed a new material' which I dont believe. Its marketing speak for "we tried lots of *ready manufatured* foam until we found one we liked best" Its gotta be out there somewhere.......

2 things seem to be critical with the foam: First is the density or 'weight' and second is the positioning/thickness. It appears that the foam used in the above FB1i pics - directly behind the driver - is flat rather than dimpled (or its 2 peices or dimple foam facing each other?).

As a "plan b" on the foam issue I'm considering Troels Gravesens approach on damping TL's.

http://www.troelsgravesen.dk/cabinet-damping.htm

He uses a combination of some kind of felt material and egg-crate/dimple foam. Obviously I would do this in a fashion that mirrored the PMC layout, and try to keep the overall thicknesses the same as PMC.

In this link to Troels site there are some pictures to illustrate what I mean:

http://www.troelsgravesen.dk/ATR-TL.htm

Any ideas/comments?

qscott
16-12-08, 04:12 AM
Hi Mike,

How are you going with your FB1+ build?

I own a pair and I'm looking at building a pair or DB1i for the bedroom, would love to hear how you've got on.

Cheers,
Q

James Evans
16-12-08, 04:18 AM
Q, do you have the driver part numbers and xover schematic for the i? Be interested to see them if you have.

cheers

James

qscott
16-12-08, 04:51 AM
Hi James,

No I don't have the details for the i series.

I do have some pic of the drivers and xover of the FB1+, not sure if I can upload to this site though.

Here are the details of the drivers.

HF - Vifa - D27TG-35-06 6 ohm - 06122004 - www.tymphany.com/d27tg35-06
LF - Vifa - M17WG-09 8 ohm - 09082002 - www.tymphany.com/m17wg-09-08

I've managed to cook one of the LF drivers and the replacement was around the $80AUD mark. The LF drivers are discontinued, but the HF is still being manufactured.

mikesnowdon
16-12-08, 11:00 AM
Hi gscott.

I havent started yet due to other projects such as my 8 month old baby girl. :D

Keep us posted on how you get on. I know James was interested in diying the DB1.

Mike.

mikesnowdon
03-02-09, 03:06 PM
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&rd=1&item=130285153900&ssPageName=STRK:MEWA:IT&ih=003

mikesnowdon
18-02-09, 07:08 PM
Interesting info on TL damping material:

http://www.diyaudio.com/forums/showthread.php?postid=1555483#post1555483

Royd Audio
13-08-09, 05:22 AM
Really interested in the outcome of this thread, as the PMC FB1 made a great impression on me when I heard it many years ago.

I wondered if it were possible to re-jig the design and have the port fire out the rear, though that would defeat the purpose of a "clone" I guess, but in my opinion is the only aesthetic failing of the design, I can't argue against it's sonic quality!!!

mikesnowdon
13-08-09, 09:07 AM
Ive not taken this past the 'idea' stage unfortunately. Mostly because of other projects and also because Im really happy with my modified TDL RTL2's. Im building a new amp currently and after that big mods are planned for my CDP. After that If all works out well with regard to improving the system sound I might get on with one of the many speaker ideas I have. I remember towards the end of last year I worked on plans for a TL version of Troels Gravesens 'Exta' design, so it would be a choice between that and the FB1 clone. I would expect the Ekta TL to sound best (3-way scanspeak) but the drivers alone would cost over double that of of the FB1. Someday....:)

mikesnowdon
04-05-10, 04:18 PM
I almost forgot about this thread :D

Looks like its been 'moderated' the crossover schematics and close up pics of the PCB are gone...Good job I still have them here then ;)

Getting tempted to do this build now. The exact drivers are clearly not OEM for the "+" version nut might be tricky to find. I think both midbass and tweeter are discontinued. Anyone know?

PS: The little one had her 2nd birthday not long ago :)

abes99
27-06-10, 02:19 AM
Hi Just come across this thread, good work
could i have the plan of the speaker and crossover, any DB1 project
long live diy, great forum
Abes

mikesnowdon
27-06-10, 06:51 AM
Hi Just come across this thread, good work
could i have the plan of the speaker and crossover, any DB1 project
long live diy, great forum
Abes

Are you actually going to build them? I love to do it myself but the funds aren't there and the drivers are hard to find.

abes99
27-06-10, 12:49 PM
yes,but i need the plan.with the help of all the members of the forum i think we can have the drivers or equivalent.must have something out there
Abes

mikesnowdon
27-06-10, 03:45 PM
Send me a PM with your email address.

abes99
28-06-10, 09:44 PM
Mikesnowdon,have you received my message
Thanks
Abes

mikesnowdon
29-06-10, 04:34 AM
Yes. I already emailed you.

macaque
05-07-10, 06:23 AM
Hi Gents,

I also just stumbled across this thread and I am also looking for the FB1+ detailed views/schematic. I actually have a set of original FB1s which had crossover problems (I have a second set of drivers which I managed to get when I didn't realize the problems were in one of the crossovers). I bought a set of the original crossovers from someone who had done the FB1+ upgrade and that fixed all my problems (and having a spare set of drivers is good). After reading some mention on other forums I tried clipping off the phase disc on the aluminum tweeter on my spare set last night. The jury is still out on that one - it seems more detailed but slightly less focused.

I know the FB1+ upgrade involves new foam too, but I am interested in trying just the new tweeter and getting the parts to redo my old crossovers so I all be able to switch between FB1 and FB1+. The original crossovers seem to have the exact same PCB board posted here. The only difference seems to be the absence of the 56 Ohm resistor in the original crossover and the 3.3 uF cap is 3.0 in the original. The other caps and resistors are the same. The coils look identical but I guess its likely the values are different? Did anyone nail down the values for these?

Thanks in advance!

mikesnowdon
08-07-10, 07:49 AM
Mike, based on the above your xover is:

http://www.spev.co.uk/fb1.gif

quickly knocked up in ppt so boxes for inductors rather than coils, but it should be clear hopefully!

Very similar to the DB1 xover unsurprisingly

Hi James.

Any chance you still have the XO schematics? For some reason they disappeared from the thread.

Cheers.

James Evans
08-07-10, 08:36 AM
Here you go Mike:

http://www.spev.co.uk/DB1/FB1.gif

macaque
08-07-10, 10:39 AM
Here you go Mike:

http://www.spev.co.uk/DB1/FB1.gif

Thanks for the schematic... I just compared against the FB1 and used some online calculators for 2nd order Linkwitz-Riley filters.

The LP circuit is identical to the original FB1 and the HP circuit adds a 56 Ohm to make an L-Pad attenuation of 1.5 dB compared to the original tweeter (original tweeter efficiency is 91 dB and new one is 92.5). The 3.3 uF vs the 3.0uF keeps the crossover at 3KHz with the extra resistance parallel to the tweeter resistance. I don't think the coils changed at all.

Also the 3.0uF cap on the original FB1 was Bennic branded (like the resistors here) and the FB1+ are Solen FC caps - and so far this is the only difference in xOver I can see that would allow PMC to claim the FB1+ had an improved crossover - all the other parts are identical and the extra resistor is purely for necessary attenuation with the new tweeter. I fact I would say the coils on my original FB1 crossover are wound more cleanly that the ones in the pictures here...

macaque
08-07-10, 12:35 PM
Now I'm confused:

http://www.solen.ca/pdf/vifa/d27tg3506.pdf

http://tymphany.com/files/products/pdf/D27TG-35-06%20Website%20Specification%20Sheet%20Rev%201_0_0 .pdf

Older version of spec sheet posted at Solen (where I ordered drivers from) - DCR = 4.6, Resonance = 650 Hz, SENSITIVITY 91dB (exactly the same DCR, Z, and Sens of D25AG-05-06 from original FB1)

Newer version of spec sheet from Tymphany site - DCR = 4.9, Res = 720 Hz, Sensitivity = 92.5 dB!!! This looks like the specs the new FB1+ crossover was trying to meet.

The mechanical spec depth is also significantly longer on the new spec sheet but both sheets claim double chamber.

I guess once I receive the drivers I'll measure the depth to decide which spec sheet to use (looks like the old one would be a direct swap in with the original crossovers)

macaque
13-07-10, 04:31 PM
And another

http://www.parts-express.com/pdf/264-1022s.pdf

Resembles electrical numbers on the Tymphany site (although slightly different) with physical dimensions similar to one on Solen site.

http://www.falcon-acoustics.co.uk/pdffiles/D27TG-35.pdf

Resembles electrical numbers on Solen site and physical dimensions on Tymphany site.

Is it typical to have so many contradictory spec sheets for the same product?

James
13-07-10, 05:43 PM
Is it typical to have so many contradictory spec sheets for the same product?
You are assuming the published specs are accurate in the first place, or there is enough product consistency from one batch to another. The only way to know for sure is to measure the drivers yourself. Anything else is pot-luck.

James

thainhnh
13-12-10, 11:12 PM
Hi guys,
Would love to get FB1 enclosure drawing. Could anybody help me!