Oh it'll ring like a bell alright.
Just because it's thicker and therefore stiffer, it doesn't mean it's less resonant. It'll be quite resonant. You telling me you've never struck a thick piece of aluminum before?
se
The CTC Blowtorch was built to try to make the very best simple preamp that we could make. Did we go too far? I don't think so, but we could 'cut a few corners' and still have an acceptable preamp. For example, the last 7 preamps that I personally had to put together, used quality copper wire, rather than silver wire. The sound was good, but slightly softer than the pure silver wire. I did an A-B test, myself.
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You can make an enclosure thicker, heavier, put braces in, and the only thing you change is the frequency at which it rings. Speaker manufacturers discovered that a century or so ago
jan didden
I make service for broken hi-fi gear, otherwise this would maybe not be a bad idea basically.
But my earlier boss saved some money due repairing broken fuses in some Conrad Johnsons with a piece of copper wire, calculated with magic cubes
. They used BUSS fuses, very expensive, but safe and tehy said, the sound is better,After the cheap fuse fix we often had blown circuits and output tubes....
I have seen some products with circuit breakers( Rowland) , because they found this the better sounding solution.
I have seen krells with regulated power supply, using dc sensors and similar protections instead of output fuses, the claimed ist sounds better.
Unfortunately they used fuses in the regulator power supply, which did NOT blow off when a capacitor there had a shortcut. This resulted in a burned stand by transformer ( this thingie sucked more than 90 Watts in standby and had no thermal protection) and the capacitor burned a hole into the board. Finally the main circuit breaker stopped the smoke and prevented a fire.
I have seen big Thresholds, when they failed, the output fuses protected themself while the output devices shortcutted themself and then the main circuit breaker did their job.
In the end, for the sound i feel its the best to avoid fuses whenever possible, without supressing safety of course.
You can make an enclosure thicker, heavier, put braces in, and the only thing you change is the frequency at which it rings. Speaker manufacturers discovered that a century or so ago
jan didden
OK, but what about the effects in the real application?
Consider two preamps, mounted on similar shelves. One has a Heavy, stiff chassis, one has a consumer-grade 0.7mm thick chassis, maybe with enough stiffening to prevent it from twisting when you pick it up.
Fire identical acoustic waves from a loudspeaker at each, from say 2m.
Which chassis transmits more of the incident acoustic energy to a circuit board inside the chassis, mounted on identical pillars?
Don't know, and I would venture that none here have really looked at this in some systematical way.
Then again, what would the effect be of the vibrations on the PCB? How about all that presumably high-end stuff with mains transformers mounted on a PCB? Or, (gasp) mains transformers mounted on the chassis, using the chassis as a sound board?
Point is, there so much speculation here it would put a stock exchange veteran to shame
jan didden
> Which chassis transmits more of the incident acoustic energy to a circuit board inside the chassis, mounted on identical pillars?
I wonder if you would be interested in energy or vibration amplitude (displacement)..
In any case, energy is force x displacement.
Force is pressure x area, so same in both cases, I assume.
Vibration amplitude is less for higher masses and higher stiffness for the same force.
As a first approximation, you can assume that the PCB will follow the case, vibrationally.
Guess you can draw your own nconclusions.
Patrick
I wonder if you would be interested in energy or vibration amplitude (displacement)..
In any case, energy is force x displacement.
Force is pressure x area, so same in both cases, I assume.
Vibration amplitude is less for higher masses and higher stiffness for the same force.
As a first approximation, you can assume that the PCB will follow the case, vibrationally.
Guess you can draw your own nconclusions.
Patrick
Hi,
You may venture.
Measurable additional noise at the mains frequency and multiples. It is often mistaken for being due to electrical/magnetic pickup and one can spend amusing lucubrations trying to reduce them...
Well, there one often gets a lot of noise being radiated by these sound boards.
I once walked into a shop, being really annoyed by the loud buzzing noise. I eventually traced it to BOTH of the very big and very expensive M..... [brand deleted to protect the innocents] monoblocks...
Indeed, the problem is there are too many here intend on scoring points in the defencing (I use the archaic form of the word on purpose) of indefensible positions (like that all that High End stuff is BS, that cheap components are as good as expensive ones, that thin sheet metal chassis are as good as more solid ones and that everything sounds the same anyway).
If they actually occasionally stopped to think about things and asked themselves some questions they might find that the world is by far more complex and as a result interesting place than they imagined...
But most prefer false certainties to true uncertainties...
Ciao T
You may venture.
Measurable additional noise at the mains frequency and multiples. It is often mistaken for being due to electrical/magnetic pickup and one can spend amusing lucubrations trying to reduce them...
Well, there one often gets a lot of noise being radiated by these sound boards.
I once walked into a shop, being really annoyed by the loud buzzing noise. I eventually traced it to BOTH of the very big and very expensive M..... [brand deleted to protect the innocents] monoblocks...
Point is, there so much speculation here it would put a stock exchange veteran to shame
Indeed, the problem is there are too many here intend on scoring points in the defencing (I use the archaic form of the word on purpose) of indefensible positions (like that all that High End stuff is BS, that cheap components are as good as expensive ones, that thin sheet metal chassis are as good as more solid ones and that everything sounds the same anyway).
If they actually occasionally stopped to think about things and asked themselves some questions they might find that the world is by far more complex and as a result interesting place than they imagined...
But most prefer false certainties to true uncertainties...
Ciao T
I think you can, too.
The stiffer, higher mass chassis face will reflect greater proportion of the incident energy. The flimsy chassis will be displaced, and transmit energy to the internals mounted to them, and reflect less.
Whether one believes this matters is up to the designer of the product.
John clearly believes it is important, and so would-be designers of high performance audio may do well to investigate it further, and decide for themselves whether it is worth pursuing. To be clear, I do not suggest that one should copy what John does, but to investigate, weigh and consider.
The effect upon various capacitors, and other components of acoustic energy has been noted here and widely elsewhere, and would be part of the evaluation.
So, Jan, there may be some speculation involved to begin with, but product design often begins with speculation. It's what you do next that counts - evaluation, comparison, redesign, and testing the finished article for fitness for its intended purpose. John's doing something right.
Hi,
Yes, however it will also have modes of it's own and the common (mis)take of making things nicely symmetrical, with equal fixing distances and fixings at halve-way points will cause multiple identical modes which hence will mutually re-enforce.
There is much interesting stuff in vibrations and in how much components react to it.
Of course, non of this matters if one holds a religious belief that vibrations don't matter.
Ciao T
Yes, however it will also have modes of it's own and the common (mis)take of making things nicely symmetrical, with equal fixing distances and fixings at halve-way points will cause multiple identical modes which hence will mutually re-enforce.
There is much interesting stuff in vibrations and in how much components react to it.
Of course, non of this matters if one holds a religious belief that vibrations don't matter.
Ciao T
Tap the chassis with the system on. Do you hear anything in the speakers? If not, you're fine. If so, track down the microphonic bits and fix them. At a five figure price tag, I expect that the engineer wouldn't use microphonic parts, but in "high end" audio, anything's possible...
Unfortunately, this doesn't work for tube phono stages or mike preamps, so a different approach is necessary (or use solid state for those applications). High Q mass won't help. Attention to isolation and suspension will. See, for example, "Building Valve Amplifiers" for some possible solutions.
Unfortunately, this doesn't work for tube phono stages or mike preamps, so a different approach is necessary (or use solid state for those applications). High Q mass won't help. Attention to isolation and suspension will. See, for example, "Building Valve Amplifiers" for some possible solutions.
Hi Rod,
AMR's site has quite well hidden some details on the take we have on this whole thing.
Here an example how I do manage vibrations in the place where we have most of them concentrated...
Abbingdon Music Research - Products - LS - 77 Photo Gallery
We also use a wide range of techniques in other products.
Ciao T
AMR's site has quite well hidden some details on the take we have on this whole thing.
Here an example how I do manage vibrations in the place where we have most of them concentrated...
Abbingdon Music Research - Products - LS - 77 Photo Gallery
We also use a wide range of techniques in other products.
Ciao T
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Hi,
Really? Interesting?
So your chassis are so airtight that air pressure changes on the outside (sound) cannot reach the insides, only directly conducted sound? That is impressive engineering.
Your tendency to overly excessive reductionism and excessively broad statements result in practically all your statements being mostly wrong and trivial to falsify. The above is no different.
Please, as I have repeatedly asked of you, upgrade the standards of evidence and precision in your statements.
Otherwise some may develop the mistaken view that you are promoting wilful ignorance as the way to understanding...
Ciao T
Really? Interesting?
So your chassis are so airtight that air pressure changes on the outside (sound) cannot reach the insides, only directly conducted sound? That is impressive engineering.
Your tendency to overly excessive reductionism and excessively broad statements result in practically all your statements being mostly wrong and trivial to falsify. The above is no different.
Please, as I have repeatedly asked of you, upgrade the standards of evidence and precision in your statements.
Otherwise some may develop the mistaken view that you are promoting wilful ignorance as the way to understanding...
Ciao T
Hi,
These are already copper foil types, with tight windings and impregnation. So they benefit a lot less than most.
However overall turning the crossover into a solid block still measurably helps. We use clear resin so no-one says we only pot the crossover to hide what we do. (BTW, the crossover is passive Chebychev 10th order)
Ciao T
These are already copper foil types, with tight windings and impregnation. So they benefit a lot less than most.
However overall turning the crossover into a solid block still measurably helps. We use clear resin so no-one says we only pot the crossover to hide what we do.
(BTW, the crossover is passive Chebychev 10th order)Ciao T
Hi Sy,
Fighting talk... I love it.
Well, let's say it like this:
That the person who designed it clearly had a MUCH better grasp of microphonics than you display in public.
And what am I continually plugging?
I have at times referenced products that I am absolutely certain not a single person here would buy anyway (they prefer building stuff themselves), to illustrate a given point.
Well, no-one complained about microphonics yet. In fact, you can happily do your test from above at any show where you find that "preamp".
Also, to be scientific about it and make sure the test is repeatable, please specify the precise force we should use to "tap" the chassis? Does it matter where we tap the chassis? Does it matter what we use to "tap" the chassis? Does it matter what volume the volume control is set to? Do we need to set it so we have a specific SPL in the room?
Anyway, once you have sufficiently clarified your "Tap the chassis" test (to be honest, it sounds folksy to me), perform it.
In my view it will however not tell you much about microphonics at all...
This is easily demonstrated BTW, that it does not.
All you need is an amp, a pair of speakers, a DUT with shorted inputs set normally, unmuted, etc. and an AP2 or similar test system.
First do your highly scientific "Tap" test.
If (and only if) your test certifies "no microphonics", please proceed.
Connect the output from your AP2 to the Amplifier and speakers, use the output from the DUT as input to the AP2. Place the DUT in the soundfield from the speakers.
If there is really no microphonics from your test you should not measure anything than the noisefloor. I find doing such tests quite instructive and a little more useful than the folksy "just tap the chassis" method, but WTFDIK.
Ciao T
Fighting talk... I love it.
Well, let's say it like this:
That the person who designed it clearly had a MUCH better grasp of microphonics than you display in public.
And what am I continually plugging?
I have at times referenced products that I am absolutely certain not a single person here would buy anyway (they prefer building stuff themselves), to illustrate a given point.
Well, no-one complained about microphonics yet. In fact, you can happily do your test from above at any show where you find that "preamp".
Also, to be scientific about it and make sure the test is repeatable, please specify the precise force we should use to "tap" the chassis? Does it matter where we tap the chassis? Does it matter what we use to "tap" the chassis? Does it matter what volume the volume control is set to? Do we need to set it so we have a specific SPL in the room?
Anyway, once you have sufficiently clarified your "Tap the chassis" test (to be honest, it sounds folksy to me), perform it.
In my view it will however not tell you much about microphonics at all...
This is easily demonstrated BTW, that it does not.
All you need is an amp, a pair of speakers, a DUT with shorted inputs set normally, unmuted, etc. and an AP2 or similar test system.
First do your highly scientific "Tap" test.
If (and only if) your test certifies "no microphonics", please proceed.
Connect the output from your AP2 to the Amplifier and speakers, use the output from the DUT as input to the AP2. Place the DUT in the soundfield from the speakers.
If there is really no microphonics from your test you should not measure anything than the noisefloor. I find doing such tests quite instructive and a little more useful than the folksy "just tap the chassis" method, but WTFDIK.
Ciao T
Someone could try a case made of Corian and the likes. (as one audio manufacturer did, but failed to sell the concept to sufficient customers)
Or soapstone, Avalanche amp, Finland.
(another 22 months before i can joyfully tap folks again)
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