Phono Stage Recommendations

[Craig Sawyers]

There are quite a few stylus profiles: conical, elliptical and shibata are but a few.

I have absolutely no problem with my Denon DL103 with a conical stylus tracking (on an SMEIV, Garrard 301 and high mass plinth).

Craig

[gramophone1]

Hi Craig, I was using a fairly rubbish dj turntable at the time I was using a conical stylus, which is probably why it didn't track very well. I think it was numark or something like that, that I got very cheap. I didn't keep it very long. The tracking was awful. I thought it was the stylus, but in fact it was because the turntable was rubbish. As you point out, you have had no problems with a conical stylus not tracking properly.

I then got a proper turntable lol. A project genie mk 3. It was ok, but i could hear the motor through the speakers. The motor was being picked up from the cartridge, which was an ortofon red series. Turntables are a hobby in themselves, and I didn't have the patience to faff about with the genie, so I give up on turntables, and have not owned one for a few years now. I once purchasded a Goldring lenco turntable (I can't remember the model number) off eBay. It was in mint condition, but when it arrived it was damaged. The previous owner had left the counter balance weight on the tonearm, and the end of the tone arm had bent during transit. Those tonearms are not one piece, and once bent it can't be repaired. The AT is perfect for me, low maintenance, plug and play

[jamesperrett]

Originally Posted by gramophone1

I once purchasded a Goldring lenco turntable (I can't remember the model number) off eBay. It was in mint condition, but when it arrived it was damaged. The previous owner had left the counter balance weight on the tonearm, and the end of the tone arm had bent during transit. Those tonearms are not one piece, and once bent it can't be repaired.

The same thing happened to me when, as a teenager, I brought home the Dynatron HFC101 that my aunt had given me. I was devastated to find the end of the arm had broken off but I managed to fix it (after a fashion) by super-gluing a thin piece of rod across the join. It probably doesn't decouple the arm from the counterweight like it should but it has held for getting on for 40 years and still works today.

[gramophone1]

Just an update on my turntable.

I decided not to buy an external preamp. I upgraded the felt mat to a Technics rubber mat, and I purchased an Audio Technica disc stabilizer. I have changed the cartridge to a reloop vibe concorde cartridge. The reloop is made by ortofon, and is superb. It has a higher output of 8mv, and tracks much better than the audio technica. Although designed for dj or studio use, it has a nice sounding eliptical stylus. The only problem now is I have rumble, and I am not sure how to cure this. I can buy a filter, but the only one I have seen available is expensive. Will rumble cause damage to my speakers?

[Edward Huggins]

You did not mention rumble before. Has this come about since your various upgrades?

I would caution against a filter as this will alter the performance of your amplifier. Check for excessive cone excursions on your speakers on a part of the record where there is no content.

[gramophone1]

To be honest, I had never heard of rumble before, until I started seriously researching phono
preamps, and noticed some of them had a rumble filter. After researching exactly what rumble is, I noticed excessive movement of my bass cones, and can only assume rumble is the cause of this. It only happens during vinyl playback. My understanding is that rumble is caused by the manufacturing natural defects of the vinyl pressing process, particularly with warped records. When the needle of the stylus tracks these defects in the vinyl it causes unnatural movement of the bass cones. I hope I got that right, if not please correct me.

On better pressings, it seems less of an issue. I am more concerned it could damage or shorten the life of my speakers.

Any advice, as always very welcome.

This is the only rumble filter I have found KAB RF1 RUMBLE FILTER, and its very expensive.

[Craig Sawyers]

OK - rumble. Several possible causes.

1. From the turntable bearing, motor or drive components.
2. From the record. Either warps, which tend to be at a low frequency on a 33.33 rpm disc, or from ripples in the vinyl
3. From acoustic feedback from the loudspeakers.

The first one is unlikely if you have a half-way decent deck in good shape. The second one is typically amplified by the effective mass of the arm+cartridge resonating with the vertical compliance of the cartridge. That can give resonant amplification by 20-odd dB at somewhere in the 5Hz to 15Hz range.

The third can be checked by dropping the needle onto a non rotating record at normal listening level. Tap the top surface of the plinth with your finger. If you have no feedback it should just go thud. If you have acoustic feedback a low frequency howl will build up.

The KAB RF1 is more than a simple rumble filter. It is a crossfeed system. The operation is based on the fact that there is no directional information under 100Hz, and indeed recording studios already mono under 100Hz to improve both trackability and get as much music on a side as possible.

Vinyl ripples and warps are all vertical in nature, and hence are antiphase through the speakers. So adding left and right subtracts the rumble.

That is what the KAB unit does.

There is another called the DeVinyliser, designed by Douglas Self and available either as just a PCB, a kit of parts or a complete board http://www.signaltransfer.freeuk.com/devinyl.htm . There is also a link to a technical presentation on that page. This is more sophisticated than the KAB unit, in that it also has a deep notch for the vertical summed signal at 8Hz to notch out arm/compliance resonance.

I have one of Self's permanently in place, and it works superbly.

Craig

[Craig Sawyers]

Self also has an article in Linear Audio V12 (Sept 2016) "Rumble filtering - like you really mean it", and also incorporates a third order Butterworth filter (at 20Hz) into both his phono stage and precision preamp.

Craig

[gramophone1]

Thanks Craig for all your advice.

Although expensive I am going to purchase the KAB RF1 RUMBLE FILTER.

This will give me peace of mind that any rumble issues will be resolved.

From the reviews I have read on this item, it does not affect sound quality in a negative way.

[Edward Huggins]

Well, by it's very nature you will loose some Bass response because of the filtering. Also you are introducing further "insertion loss" into the soundchain.
The unit must be fitted after the seperate pre-amp, not from the pick up directly.
To me this still seems a very expensive fix for what may be some inherent deficiencies in your existing set up, whether it be the TT mounting or an issue with its mechanics...?

[gramophone1]

Thank you for the advice. I will have to think this through more, and see if I can root out the problem.

[gramophone1]

I have managed to locate the problem causing the rumble. It is the records themselves that are causing the problem. On a really good vinyl pressing there is no rumble at all, but on other vinyl the rumble varies in severity. It must be coming from the vinyl recording. I don't think there is much I can do about it, apart from using said rumble filter, which is expensive.

The big question is, will rumble damage my speakers, or shorten there lifespan.

[ajgriff]

Originally Posted by gramophone1

The big question is, will rumble damage my speakers, or shorten their lifespan?

I'll probably be shot down in flames but having played vinyl (plenty of rumble!) for decades without using a rumble filter I believe the answer to the question is a resounding 'no'. Don't waste your money!

Alan

[Radio Wrangler]

Use the british standard eyeball to look at the cone movement in your bass drivers. If the rumble is taking them to the limits of their travel, then damage is very likely. If not then they should take it for some time, but you're wasting a lot of your amplifier's power capability and heating voice coils unnecessarily. The latter will decrease their life expectancy.

David

[Craig Sawyers]

Originally Posted by ajgriff

I'll probably be shot down in flames but having played vinyl (plenty of rumble!) for decades without using a rumble filter I believe the answer to the question is a resounding 'no'. Don't waste your money!

Alan

There have a number of questions been asked. In response to the above - it depends on the low frequency response of your speakers. Closed box speakers have a second order high pass response. So they are less capable of revealing low frequency non-musical content than bass reflex or open baffle speakers. Bass reflex have no driver loading near DC, and are very prone to cone flap on very low frequency content. Likewise open baffle loudspeakers.

Edward Huggins said:

Well, by it's very nature you will loose some Bass response because of the filtering.

Not with a cross-feed you won't.

And if you have a third order filter at (say) 20-30Hz you won't lose bass either.

The lowest fundamental frequency (the open E-string) of a bass guitar is 41Hz; An orchestral double bass is likewise 41Hz. An 88-key grand piano lowest note is 32Hz. The only common-ish instrument that goes lower is the foot pedals of a large organ which will produce an audible output at 16Hz.

So a low frequency rumble filter with a 20Hz cutoff cannot possibly significantly reduce bass content from a vinyl record.

Also you are introducing further "insertion loss" into the soundchain.

Pardon? Don't understand...

"To me this still seems a very expensive fix for what may be some inherent deficiencies in your existing set up, whether it be the TT mounting or an issue with its mechanics...?"

As I said earlier, if a turntable and cartridge is sufficiently high quality, mechanical "rumble" from this source is unlikely. But it is always present on the vinyl medium, from warps and ripples in the vinyl itself. And depending - as stated above - on the design of the OP's loudspeakers - the bass drivers could well run out of linear excursion and thermal limit on low frequency non-musical vinyl medium content - as David has suggested.

Craig

[Edward Huggins]

What I mean by "Insertion Loss" is that the OP would adding further elements into the signal chain - viz: PU to Pre-Amp, Pre-Amp to Bass Filter, Bass Filter to Amp. If the turntable does not have pre-fitted cabling, that will neccessitate the use of 3 sets of RCA cables and connectors.

[ajgriff]

In the real (rather than theoretical) world I wonder how often bass drivers are damaged by vinyl generated rumble?

Alan

[Craig Sawyers]

Even if the bass driver does not hit the end stops you get two undesirable effects:

1. Heating the voicecoil increases its resistance. Between room temperature and the thermal limit of the voicecoil (~150-200C) the copper coil increases in resistance from 8 ohms nominal (say) to 14.4 ohms. So, because the driver is a current driven motor the sensitivity drops by 5dB. This is called power compression.

2. Doppler distortion. Because the cone's motion is high amplitude at low frequency, higher frequencies are doppler shifted.

3. Non-linear distortion. Any driver has increasing distortion with amplitude of motion. So any audio signal riding on top is also having increased distortion. We are talking of an increase of ~1% to ~5% or more.

So even if you don't blow your driver, there are several downsides to not having some form of "rumble" filter to get rid of LF rubbish.

Of course it does not prevent your cartridge from generating distortion as a result of high motion amplitude at the arm mass/cartridge compliance resonance. The only way around that is to apply viscous damping at the cartridge (like Shure did with the V15IV onwards) or at the arm pivot (like SME and Townhend).

Craig

[gramophone1]

Does anyone know where I can buy a separate rumble filter, other than the insanely priced KAB. Unfortunately I don't have the skills to build my own from a kit.

The only other way I can think of, is to buy a phono preamp with a rumble filter built in. I don't know how effective these are. But I want to avoid that if possible, because the phono preamp in my av receiver is more than sufficient for the job.

Any suggestions most appreciated

[Ted Kendall]

I think you can buy the Devinyliser ready built from the Signal Transfer Company. It is then a relatively simple matter to put it in a box with a power supply. It is to my mind the best thought-through rumble filter yet devised. There's plenty of hand-holding available here to guide you through the process.