Turntable aggresive sound, top plate? - diyAudio
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Old 12th May 2007, 02:44 PM   #1
iain is offline iain  United Kingdom
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Default Turntable aggresive sound, top plate?

I modified my TT an Avondale Genesis (Think Voyd Valdi, but better) a few years ago and possibly got carried away.

When I re-assembled it I also changed the arm to an Origin Live Encounter. I replaced the wooden top and bottom plates with 3mm Aluminium and bolted them together so as not to foul the sub platter.

The whole thing sounded significantly more detailed, but very fierce. Adding more bolts and lining the sub chassis and insides of the plates with blu tac cured most of this, but it still errs in this direction, which mars an otherwise great sound.

I have plans to "float" the bearing as suggested by Ynwoan, but would be grateful for some advice on whether I am hearing too much aluminium, any better materials to try or is this likely to be something else? Arm, arm cable?

I have fiddled endlessly with the VTA and weight. Changed cartridges. Phono stage is a TEAD Groove. And other sources sound clean?


Cheers

Iain
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Old 12th May 2007, 03:27 PM   #2
iain is offline iain  United Kingdom
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.........Is there any mileage in changing the arm board, which is alu too. What differences would acrylic or wood make?
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Old 12th May 2007, 08:34 PM   #3
marekst is offline marekst  Poland
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I tried the Encounter on VPI Scout and on my DIY turntable. Both tables are on the relaxed side but Encounter sounded exactly like you described Ė fierce and arrogant too. I quickly sold the OL tonearm, made a couple of Schroeder clones and the sound is pleasant without loss of details and dynamics.
Marek
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Old 13th May 2007, 09:30 AM   #4
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The 4 inch solid maple platform under TT treated me similar problem nicely.
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Old 14th May 2007, 02:27 PM   #5
YNWOAN is offline YNWOAN  United Kingdom
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Hi Iain, here are my thoughts regarding your turntable issues:

In my experience turntables can be viewed almost like musical instruments. Altering absolutely anything on one is likely to have some kind of sonic consequence. Material changes (as opposed to design changes or altered construction methods) usually have an effect on tonal balance. Often these tonal changes are quite complex and do not necessarily effect all frequencies evenly. As a result the subjective effect can often be to 'increase' detail retrieval or bass extension. This, I suspect is what you have done, by changing the plinth into a much more rigid affair you have significantly altered its sonic 'signature' and the overall balance. However, it does not necessarily equate that what you have done is wrong. It is possible that your deck is now more transparent to shortcomings elsewhere in your system. In particular I would look toward the character of both your arm and your cartridge. I simply state this as a possibility as I am not personally familiar with the equipment you use. In the early days of developing my own equipment I was lucky enough to be able to compare my design to a current Linn LP12 with the same arm and cartridge.

Changing the material that your arm board is made of will have an effect on the sound produced. In general a less stiff material will give a softer sound. However, you may also find that the mid bass is bloated subjectively compared to a stiffer material (I am specifically thinking of acrylic here in terms of a softer material). I have recently constructed a composite carbon fibre arm board for my own deck and will keep you posted once I have got round to fitting and comparing it. It is also possible that tuning the torque of the bolts on both your top/bottom plate and your arm board may yield the effects you seek. Altering the tension of these components will certainly have an effect but I canít guarantee that it will be the one you are looking for. Finally, I'm afraid that I am not as great a believer in the damping properties of blue-tack as some. I would rather a second layer of material was bonded to the first (a contact adhesive like Thixofix is good for this).
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Old 17th May 2007, 09:05 PM   #6
iain is offline iain  United Kingdom
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Thanks for your replies.

I have an ET2 which I have not used for about 10 years. So I think I will give that a go.

It used to sound lovely, no distortion. But abit flat and lacking in dynamics compared to the OL250 that replaced it. Will give a useful comparison though.

I think Ynwoan is right about TT's. The difficult thing is where to go next. I have empasised the upper frequencies and reduced the lower ones.

I could go back to the old wooden top plate-I have thought about carbon fibre, but £60 for an experiment is too much!

I could try a better way of damping the aluminium, bitumous pads, plywood.

I have it mounted on long aluminium feet so the Groove can sit underneath. I could try changing them.

I look forward to hearing about your arm board Ynwoan.

I will carry on posting if I make any interesting discoveries

Thanks again everyone
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Old 17th May 2007, 10:20 PM   #7
YNWOAN is offline YNWOAN  United Kingdom
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If it is relatively easy to do, I suggest you make an acrylic arm board and see what you think. The advantage of doing this is that it will help calibrate (in a subjective sense) your expectations and significantly advance your experience. Your thoughts on the subjective effects of this mod would be very helpful to both yourself and to myself (in terms of giving advice). If making the arm board is an issue I am prepared to make one for you (this is not an offer to make one for anybody else - sorry). Also, I have an acrylic mat that you could try (borrow) - please PM me.

I'm afraid that I feel rather frustrated by many of the turntable threads on this (and other) forums. Most of the so called experimentation is really an attempt to pursue a specific concept (blindly I feel|) or 'copy' an existing design or ideology. Very little (if any) true experimentation takes place. For example, at present, there seem to be two camps of DIY turntables; one seems to be to make as much as possible out of as little as possible and the other is for high mass, non-suspended designs. The former is good fun but hardly 'pushing the envelope', the second I believe to be intrinsically flawed (and yes, I did take this rout many years ago).

On re-reading the first paragraph I realise it may seem as though I am recommending the use of acrylic - this is not, in fact, the case. I simply recommend it's use in this case for it's specific sonic 'character' and the fact that I have used it in the past and feel that I have some understanding of its properties.
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Old 19th May 2007, 10:39 AM   #8
iain is offline iain  United Kingdom
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YNWOAN: Thanks for your kind offer, but I am hoping to do this myself. If unsuccessful I will get back to you though, thanks.

I was thinking of trying some decoupling between the bolts that hold the 2 plates together. They are inside aluminium tubes, which are slightly stressed as the whole assembly is tightened. I might put a rubber washer in place of the metal one. So I still stress the tubes, but get a bit of damping/decoupling.

Easier to try a new arm plate first though! I have put equipment feet under the arm board instead of the aluminium spacers at the time I think they helped a bit.

I am also tempted to try a better damping material instead of the blue tac; Plywood or bitumous pads.

I agree with you about some of the TT ideas. I am not a fan of bigger and heavier, but I have found that removing the springs from my TT and replacing them with demi-John corks made a small improvement in sound and a big improvement in ease of use. So I have gone off sprung suspensions a bit to.

This loss of springs would help the ET2 work now, it used to tip the suspension.

I will pm you to see if you are up for a visit one evening. I am tempted to bring my TT!
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Old 19th May 2007, 01:02 PM   #9
YNWOAN is offline YNWOAN  United Kingdom
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A visit would be most welcome - definitely bring your turntable. A comparison between the two decks would be most interesting; I have a convenient place for it to sit near to my pre-amp :-)
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Old 31st May 2007, 01:36 PM   #10
iain is offline iain  United Kingdom
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Default DOH!

Doh! and double Doh!

Decided to check everything again before taking the TT apart.

I was undertracking! Only by a smidgen, but enough to aggravate the sound. feeling pretty foolish and may have damaged a few discs! But an easy solution.

Thanks for everyones help though.

I am looking at trying to build a magnetic bearing or unipivot arm now as I think the remaining dviation fro smoothness is down to the gimbal bearings.
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