Houdini

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CaterhamKev
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Re: Houdini

Unread post by CaterhamKev »

This is one of the only threads that interests me. The other being DQs enzyme adventures.

No. I am an engineer, nit a wide eyed innocent.

It is a well known fact that you cannot easily control vibration between elements if they are rigidly linked.

If you believe that I am shilling this, then you are wrong. There is nothing in it for me. (I am happy to PM you my invoice so you can see I was charged full price). I am a happy user. I also like my isolator in conjuction with my music maker, but I have never tried the music maker without the isolator to see if it makes any difference. It was like that when I bought it, and as the isolator is pretty much single use, I am reluctant to peel the cartridge off to see if it makes a difference. I wanted to, but as I cannot replace the glue, I thoughtvtwice about it.

As said before, I am a happy user of a Houdini. That is all. There are some interesting points raised here both for, and against.

I am in no way linked to the Funk Firm, other than being a previous customer.

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savvypaul
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Re: Houdini

Unread post by savvypaul »

I look forward to you contributing to the rest of the forum.
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TheMarlin (Tue Oct 13, 2020 11:02 am)
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Geoff.R.G
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Re: Houdini

Unread post by Geoff.R.G »

As I sit here considering the idea of decoupling the cartridge from the arm I have in front of me a large diameter condenser mic in a vibration isolating mount. The principle behind the microphone and the magnetic cartridge are essentially the same, vibrations move a coil and/or a magnet, in relation to each other, the interaction between the magnetic field and the coil creates an emf (signal) which is then amplified.

In both cases the vibration moves a small mass, stylus and coil/magnet or diaphragm and coil, which is attached to a larger, fixed, mass (magnet or coil and a casing. Ideally movement of the moving part does not move the fixed part. Unfortunately, in the case of the phono cartridge this isn't what actually happens, very low frequency inputs, such as record warp or eccentricity, cause the cartridge to move vertically or horizontally. The more inert the cartridge and arm combination the less they move in response to movement of the stylus. In the case of the microphone the mass of the body is considerably greater than that of the diaphragm and coil, very rarely do we observe a microphone move in response to movement of the diaphragm.

With large microphones it is common to use a shock mount to isolate the microphone from the suspension, the input sound isn't able to move the mass of the microphone so the effect of the mount is to prevent movement of the casing in relation to the diaphragm. Years of experience in the recording industry shows that this works. Smaller microphones may have internal decoupling to minimise handling noise.

That the input to a phono cartridge is able to cause physical movement of the cartridge body, plus the arm, is evident when we play a warped record. The effect I would expect this to have on the output is in terms of dynamics, a rapid transient will move the coil/magnet at the same time as moving the body, coil/magnet the other way thus compressing, to some extent, the output. Intentionally decoupling the cartridge from the arm would, I suspect allow the cartridge to move more freely and thus further compress the transient.

With a microphone it is extremely simple to make the body more inert, not so with the phono cartridge. I wonder, has anyone tried the opposite and increased the mass at the head shell, and additional mass at the counter balance?

Just some thought brought about by looking at a microphone, I could have this all wrong and decoupling could be exactly what is needed but I don't think so.

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Re: Houdini

Unread post by Vinyl-ant »

Ive found that silicone damping via a damping trough and paddle helps alot with controlling resonances in arm/cartridge systems. If a cart is isolated from the arm it shouldnt excite resonances in the arm itsself, but, its own structural resonances will affect its output as there is nowhere for them to go. Peronally i think this is what i heard with the cartridge man isolator. Normally, the cartridge resonances would be dumped into the arm and shunted away, the problem resonances that match and excite the arm are the ones to look at.
Silicone damping will damp higher frequency oscillations more than lower frequency i would have thought, and the viscosity of the silicone fluid will have a bearing on the frequency range it will damp
Ive tried this out with various arm designs ive penned and built over the years, and have come to the conclusion that there is no one size fits all solution. There are simply too many variables.
I keep looking at how to measure the resonant behaviour of arms as it interests me, getting hold of an accelerometer small enough not to influence its own measurements has been a stumbling block
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CaterhamKev (Tue Oct 13, 2020 12:36 pm) • valvesRus (Wed Oct 14, 2020 9:58 am)
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CaterhamKev
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Re: Houdini

Unread post by CaterhamKev »

savvypaul wrote:
Tue Oct 13, 2020 10:54 am
I look forward to you contributing to the rest of the forum.
Winter is coming, so I will have more time.
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savvypaul (Tue Oct 13, 2020 1:27 pm)

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Re: Houdini

Unread post by Geoff.R.G »

Vinyl-ant wrote:
Tue Oct 13, 2020 12:04 pm
Ive found that silicone damping via a damping trough and paddle helps alot with controlling resonances in arm/cartridge systems. If a cart is isolated from the arm it shouldnt excite resonances in the arm itsself, but, its own structural resonances will affect its output as there is nowhere for them to go. Peronally i think this is what i heard with the cartridge man isolator. Normally, the cartridge resonances would be dumped into the arm and shunted away, the problem resonances that match and excite the arm are the ones to look at.
Silicone damping will damp higher frequency oscillations more than lower frequency i would have thought, and the viscosity of the silicone fluid will have a bearing on the frequency range it will damp
Ive tried this out with various arm designs ive penned and built over the years, and have come to the conclusion that there is no one size fits all solution. There are simply too many variables.
I keep looking at how to measure the resonant behaviour of arms as it interests me, getting hold of an accelerometer small enough not to influence its own measurements has been a stumbling block
I have only one thing to say to that "Laser interferometry".

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Re: Houdini

Unread post by Daniel Quinn »

Mr Sircom thinks it deos what it says on the tin. He's much more favourable than even cagey... O dear.

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Re: Houdini

Unread post by Copperblue »

Arthur K is a bit of a genius when it comes to vinyl replay IMHE. A lot of his historical ideas were often trashed at the time of introduction (DC motors, balanced force drive systems, acrylic platters, inverted bearings, light and stiff materials for sub-chassis and tonearms etc) but most of them have stood the test of time.

I have not heard the Houdini yet but I would not discount it as foo, the mans track record is too good for that - I plan to listen to one very soon.
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savvypaul
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Re: Houdini

Unread post by savvypaul »

Putting extra weight into the arm at the headshell end will certainly do 'something'. And, I am open to the idea that somehow isolating the cartridge from the headshell, to some degree or other, might also have an effect. So, in those respects, it is not snakeoil or foo.

The more thorough reports I've read suggest that sometimes the presentation is preferred with the Houdini, but just as often it is preferred without the Houdini. That, suggests to me a change in presentation rather than a clear improvement. Arthur said recently that this device had sat in his draw for 18 years. I suspect that was because sometimes it 'worked' and sometimes it did not.
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Latteman (Sun Nov 01, 2020 3:25 pm)
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Re: Houdini

Unread post by guydarryl »

Geoff.R.G wrote:
Tue Oct 13, 2020 2:48 pm
Vinyl-ant wrote:
Tue Oct 13, 2020 12:04 pm
Ive found that silicone damping via a damping trough and paddle helps alot with controlling resonances in arm/cartridge systems. If a cart is isolated from the arm it shouldnt excite resonances in the arm itsself, but, its own structural resonances will affect its output as there is nowhere for them to go. Peronally i think this is what i heard with the cartridge man isolator. Normally, the cartridge resonances would be dumped into the arm and shunted away, the problem resonances that match and excite the arm are the ones to look at.
Silicone damping will damp higher frequency oscillations more than lower frequency i would have thought, and the viscosity of the silicone fluid will have a bearing on the frequency range it will damp
Ive tried this out with various arm designs ive penned and built over the years, and have come to the conclusion that there is no one size fits all solution. There are simply too many variables.
I keep looking at how to measure the resonant behaviour of arms as it interests me, getting hold of an accelerometer small enough not to influence its own measurements has been a stumbling block
I have only one thing to say to that "Laser interferometry".
Not convinced that measuring, in itself, would help very much.

I took a bunch of pupils to Celestion speakers at Foxhall road in Ipswich (must have been about 25 years ago) and it was fascinating to watch them using laser interferometry to study and develop loudspeaker cones - I think that they may have been the first company to use this technique in this way.
I didn't like their speakers very much though :think: it must be a matter of knowing what to do once you have the observations/measurements.
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