Are the 322 phono boards in a Naim 32-5 designed with a warp filter?

Can anyone recommend a stand-alone phono stage which is not fitted with a warp-filter? Something that I can alter the loadings/settings on would be handy. I'm thinking that a DIY valve stage might lend itself to a bit of tinkering and open up the sound but I'm really open to suggestions.

Does anyone make a Class D phono-stage (bit like my T-Amp) without a warp-filter?

Are the 322 phono boards in a Naim 32-5 designed with a warp filter?



Nah mate, impulse drive only.

At a very real risk of looking a prat, what is this guy on about?

Hi garyi,
I'm probably the prat as I may be using the wrong terminology. However I'm given to understand that most phono stages are 'tuned' to stop warped records causing cone-flap in your speakers. I guess it's some kind of filter that stops really low frequency signals from reaching the speakers. There is actually a reference to a 'warp-filter' in the review of the AQVOX phonostage in the March edition of HI-FI World (p42) so hopefully this proves I'm not completely bonkers.

Since I posted this query I've found that some of the Gram Slee phono stages offer this option but I'll still welcome any other suggestions (apart from setting phazers to stun!!).

Relax Faz, we've obviously all been watching too much Star Trek.

Faz I don't understand how a warped record would cause cone flap?

My understanding of cone flap could be from a clipping amp or stupid low level signals, a warp in my experience typically produces a noise one would expect from a cartridge which has just jumped, that is unpleasant but not cone flap.

As there has been plenty of posts here and elsewhere regarding cone flap, one must conclude that a specific filter is not involved.

Any filters must be regarding MC or MM carts in terms of output?

I thought that was rather obvious: the cartridge reads the vertical modulation and passes that through the electronics to the speakers. If those speakers are ported, the drivers are unloaded below the resonant frequency of the port/box volume, and thus have no resistance to the warp-generated infrasonic signal. Result: flapping cones.

I had this problem with one particular system configuration, exacerbated by a tube power amp with poor damping. Very annoying, as a large part of my vinyl became unplayable. I had to mothball my MC and use a Shure V15 with it's little warp-riding brush thingy until I'd sorted out a more satisfactory system.

I thought that was rather obvious: the cartridge reads the vertical modulation and passes that through the electronics to the speakers. If those speakers are ported, the drivers are unloaded below the resonant frequency of the port/box volume, and thus have no resistance to the warp-generated infrasonic signal. Result: flapping cones.

I had this problem with one particular system configuration, exacerbated by a tube power amp with poor damping. Very annoying, as a large part of my vinyl became unplayable. I had to mothball my MC and use a Shure V15 with it's little warp-riding brush thingy until I'd sorted out a more satisfactory system.

A more satisfactory solution,:o i love the 'brush thingy' :) and never get bored of watching it spring into action, keeps my needle clean too.

I've already trashed one needle on my xMR less than a year ago and at £225 a pop (RRP) i err on the side of caution these days , I know that many purests will think that using the brush has a major detrimental effect on sound quality. I'd agree that i might have a detrimental effct , however i don't reckon it is major.

I know that test records don't = real music but they can be a useful tool, especially for initial setting up. If you have one at your disposal check out the difference of the V15 with and without brush, it don't half help keep the needle well into the groove.....

A warp filter is simply a response roll-off at low frequencies which is often built into phono circuits to prevent sub 20Hz frequencies being amplified. Cartridges generate lots of low frequency rubbish between 5-15Hz due to the interaction of record warps and the LF cartridge/arm resonance.

Ported speakers show this easily but it is still present even on sealed box speakers - you just don't see it as easily. Sub 20Hz signals from vinyl simply wastes power and adds distortion. It can be a major problem with tube amps as it can cause the output transformers to saturate since the power bandwidth of transformers is poorer at the frequency extremes.

I like warp filters as I think they give better bass quality - all other things being equal. I modified my WAD phono stage to roll off bellow 20Hz.

I thought it was pretty obvious what he was talking about. A rumble filter or sub sonic filter ie. that cuts everything below 20Hz or so out so's you don't get cone flap if the arm/cart resonance is a bit iffy, if you've got a bit of a rumbly bearing or you are getting some serious low level feedback (sounds like some imodium might help more :) ). Used to be pretty normal on built in phono stages on integrateds way back when - these days the suggestion might be to sort the problem out at source, though I guess in some circumstances it could be useful.

Its actually a rarity these days. I confess though I dunno about the 322 phono boards and whether they does or they doesn't. As to others its probably easier to point out ones that I know do - The Pro-Ject SE does, but its switchable - also has some loading options. The Pro-Ject Tube box does, but isn't switchable. Anyone else know of those what do, so Faz can avoid?

Addendum: Hey Robert, you beat me to it :)

I've damaged my woofer coils playing LPs at highish levels due to extreme cone excursions caused by subsonics. Warp filters (subsonic filters) can help, but I've found that matching the arm and cartridge WRT getting the ressonance frequency away from warp frequencies is a very good solution. Warp filters have to be very steep (and thus bad on the phase) to work or they will attenuate the very lowest frequencies which is audible.

Uncle Ants beat me. Just want to add, that acoustic feedback can also be a factor in cone flap.

I've already trashed one needle on my xMR less than a year ago and at £225 a pop (RRP) i err on the side of caution these days ,

You know that until they discontinued the V15 (more fool them), Shure had a no questions asked stylus replacement program for the V15VxMR. Send them your old stylus and your credit card details and for $50, they'd send you a brand new one?

They've officially stopped doing it now, but a little bird told me that if you send them your duff one as though you never heard they'd stopped it, you'll get a new one in the post for $50 ... so I heard.

Had I known that PFM is actually a cover for the UK branch of the Star Trek fan club I might have worded my query a bit differently. But thank you all for your replies, especially the ones that confirm that I'm not talking out of my a***.

The WAD phono stage was an option until they went out of business. Shame 'cos I liked the idea of being able to mod it to my own requirements. Perhaps I can pick one up s/h.

Now, can anyone tell me if it's possible to power my hifi using dilithium crystals????

The WAD phono stage was an option until they went out of business. Shame 'cos I liked the idea of being able to mod it to my own requirements. Perhaps I can pick one up s/h.


Shouldn't be too hard. Put in a "want" into the new world design forum and I reckon you might get lucky sooner than you imagine. Its where all the old WAD tyros have gone now that WAD seems to have gone belly up.

here: http://www.world-designs.co.uk/forum/

Had I known that PFM is actually a cover for the UK branch of the Star Trek fan club I might have worded my query a bit differently. But thank you all for your replies, especially the ones that confirm that I'm not talking out of my a***.

The WAD phono stage was an option until they went out of business. Shame 'cos I liked the idea of being able to mod it to my own requirements. Perhaps I can pick one up s/h.

Now, can anyone tell me if it's possible to power my hifi using dilithium crystals????

Pressure is mounting on the new company World Designs to bring it back.
WD have also made an offer to buy the entire remaining stocks at WAD.
The Phono II is a simple and elegant circuit that sounds superb. It will even take the output of a Denon 103 direct without a MC step-up without noise becoming intrusive.

You know that until they discontinued the V15 (more fool them), Shure had a no questions asked stylus replacement program for the V15VxMR. Send them your old stylus and your credit card details and for $50, they'd send you a brand new one?

They've officially stopped doing it now, but a little bird told me that if you send them your duff one as though you never heard they'd stopped it, you'll get a new one in the post for $50 ... so I heard.

Hmm, funnily enough, the stylus assy currently fitted to my V15VxMR is about 9 months old, was sent to my house directly from the Manufacturer and my credit card was $50 heavier just a couple of weeks before that.

Some clouds do have silver linings.... :D

The uneven surface of records can produce subsonic problems. So even if your hardware is perfect the software can cause problems. I think a (switchable) SF is a good thing