John Curl's Blowtorch preamplifier part II - Page 1387 - diyAudio
Go Back   Home > Forums > Member Areas > The Lounge

The Lounge A place to talk about almost anything but politics and religion.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 13th July 2011, 05:59 AM   #13861
diyAudio Member
 
Steve Eddy's Avatar
 
Join Date: Sep 2002
Location: Sacramento, CA
Quote:
Originally Posted by john curl View Post
Perhaps, Steve. And perhaps not. Everyone else, just tap your audio and video equipment with your fingernail and hear what happens.
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 Audio Guild
  Reply With Quote
Old 13th July 2011, 06:01 AM   #13862
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
Just my preamp, Steve.
  Reply With Quote
Old 13th July 2011, 06:25 AM   #13863
diyAudio Member
 
john curl's Avatar
 
Join Date: Jul 2003
Location: berkeley ca
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.

Last edited by john curl; 13th July 2011 at 06:31 AM.
  Reply With Quote
Old 13th July 2011, 08:02 AM   #13864
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: Great City of Turnhout, Belgium
Blog Entries: 7
Quote:
Originally Posted by Steve Eddy View Post
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
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
__________________
If you don't change your beliefs, your life will be like this forever. Is that good news? - W S Maugham
Check out Linear Audio!
  Reply With Quote
Old 13th July 2011, 08:40 AM   #13865
diyAudio Member
 
Join Date: Apr 2008
Quote:
Originally Posted by scott wurcer View Post
If you're DIY why not use fusable links of silver wire?
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.
  Reply With Quote
Old 13th July 2011, 08:48 AM   #13866
работник
diyAudio Member
 
Rod Coleman's Avatar
 
Join Date: Jul 2004
Location: Warwickshire UK
Quote:
Originally Posted by janneman View Post
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?
  Reply With Quote
Old 13th July 2011, 09:19 AM   #13867
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: Great City of Turnhout, Belgium
Blog Entries: 7
Quote:
Originally Posted by Rod Coleman View Post
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
__________________
If you don't change your beliefs, your life will be like this forever. Is that good news? - W S Maugham
Check out Linear Audio!
  Reply With Quote
Old 13th July 2011, 09:50 AM   #13868
EUVL is offline EUVL  Europe
diyAudio Member
 
Join Date: Oct 2003
> 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
  Reply With Quote
Old 13th July 2011, 10:04 AM   #13869
Previously: Kuei Yang Wang
 
Join Date: Nov 2002
Hi,

Quote:
Originally Posted by janneman View Post
Don't know, and I would venture that none here have really looked at this in some systematical way.
You may venture.

Quote:
Originally Posted by janneman View Post
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?
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...

Quote:
Originally Posted by janneman View Post
Or, (gasp) mains transformers mounted on the chassis, using the chassis as a sound board?
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...

Quote:
Originally Posted by janneman View Post
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
  Reply With Quote
Old 13th July 2011, 10:10 AM   #13870
работник
diyAudio Member
 
Rod Coleman's Avatar
 
Join Date: Jul 2004
Location: Warwickshire UK
Quote:
Originally Posted by EUVL View Post
> 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 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.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



New To Site? Need Help?

All times are GMT. The time now is 02:42 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2