New Doug Self pre-amp design... - Page 52 - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 14th August 2012, 10:01 AM   #511
owdeo is offline owdeo  Australia
diyAudio Member
 
Join Date: Jun 2003
Location: Sydney
Hi Steve,

I know this argument well. I've seen schematics for a few recording and broadcast consoles and they were full of 5532s, TL072s and cheap electros. (I have heard that some of the most highly regarded ones sonically (eg Neve) contain more expensive components though - don't know if that's true). It's hard to dispute if you believe 100% that THD, FR and noise measurements completely define whether equipment could cause sonic degradation. However if you say the same thing but with the assumption that every part of the recording chain IS degrading the signal, the statement then becomes: "the signal has already been degraded so much during the recording process that the equipment used for reproduction cannot matter" - which is perhaps not such a rational argument?

I mention this because I think so much of my record collection is badly recorded. For example, how many pianos have you heard in real life from a normal distance that sound like you have your head inside the lid and the bass strings are 3 metres away from the treble strings? Yet for some reason most pianos seem to get recorded that way. I could go on...

I also can't understand why the preamp passing line level signals with essentially no or very little gain has such a big effect on the sound of the system as a whole, but it does seem to - possibly equally or more so than the power amp. Rationalise that!

I agree the the 5532 is a great opamp - even cost aside. I don't think it's any coincidence that it sounds good while also producing the lowest distortion and noise in these sort of applications amoung the cheap opamps. But interestingly recently I have found that different brands of 5532 seem to sound different. Happily I don't think anyone commenting here has poo-pooed them either other than suggesting trying some different types to see if the sound is different. I certainly wouldn't have embarked on building a preamp littered with them if I thought they couldn't sound good. I think they must be essentially harmless sonically if used in certain ways, hence why I think what I'm hearing with this design comes down to the particular circuit configuration. But I'm talking about small differences that would not bother someone without a passion for hifi - ie audio rationalists (is that a sensible term to use?)

Cheers,
Owdeo
  Reply With Quote
Old 14th August 2012, 10:21 AM   #512
FdW is offline FdW  Netherlands
diyAudio Member
 
FdW's Avatar
 
Join Date: Feb 2009
Location: Both feet on the ground (near Gouda)
Quote:
Originally Posted by owdeo View Post
However if you say the same thing but with the assumption that every part of the recording chain IS degrading the signal, the statement then becomes: "the signal has already been degraded so much during the recording process that the equipment used for reproduction cannot matter" - which is perhaps not such a rational argument?
I donít think so; I see every step/device in the process/chain of reproducing sound as a musical instrument in itself. When looked at it in this way, the output of each stage is an 'original' reproduction. So, whatever the influence is of the next stage, the components/process of the next stage will influence the reproduction of its input (previous stage) and this may be measurable/hearable/detectable in any/many way(s), by human or machine The result may be pleasing or dis-pleasing, but there will be a result, and most of the time it will not be neutral/undetectable.
  Reply With Quote
Old 14th August 2012, 12:02 PM   #513
owdeo is offline owdeo  Australia
diyAudio Member
 
Join Date: Jun 2003
Location: Sydney
Quote:
Originally Posted by janneman View Post
It's online here:
http://www.linearaudio.net/images/on.../volume1bp.pdf
If you find the math intimidating, at least read the three 'storylines'.
Thanks Jan, very interesting and is going to take a few reads to absorb fully.
I note the following paragraph:

"I surmise that, since the amplifierís distortion was never negligible, mak-ing it constant across the audio band makes it fly under the psychoacoustic radar more easily. My
own subjective experience would support this. To my ears, amplifiers with the normal 20dB/decade
behaviour but whose distortion is not negligible at the end of the audio range have glassy mid-highs, a ďsuperglue stereo imageĒ as KK once put it and the illusion of spectacularly, unnaturally
tight and impossibly controlled bass. Some love this, and seceded into a subculture of ultra-beefy
amplifiers. I donít and when forced to make a choice Iíll take higher but consistent distortion across
the band."

What's this - a reference to how we perceive distortion and the author's speculation based on his own unscientific subjective experience? Shock horror! Naughty naughty, what will the hardcore objectivists say?

I agree with the description but my own subjective experience has been that all the "Lin" configuration amps I've heard sound this way. An obvious disprover of his theory re rising THD causing it is the Leach amp, which has rapidly rising THD at HF from low levels at LF and yet exhibits none of the "glassiness" etc.

Speaking of Leach I think some of what is covered regarding TIM and GBW etc is covered very succintly and more simply in the Leach amp FAQ section where he explains what "low feedback" actually means and where various pundits are telling him he should have used various other techniques in his amp to give more gain or BW and he explains why this would not make any difference when the GBW product is fixed by design.

Sooooo, getting back to the preamp, perhaps the effect I'm hearing is caused by not enough feedback around the active gain control Thank goodness we all now understand that too much feedback is barely enough!
  Reply With Quote
Old 14th August 2012, 04:36 PM   #514
redjr is offline redjr  United States
diyAudio Member
 
Join Date: May 2011
Location: Danbury, CT
Quote:
Originally Posted by owdeo View Post
Thank goodness we all now understand that too much feedback is barely enough!
__________________
redjr
  Reply With Quote
Old 15th August 2012, 12:23 AM   #515
owdeo is offline owdeo  Australia
diyAudio Member
 
Join Date: Jun 2003
Location: Sydney
Quote:
Originally Posted by FdW View Post
I donít think so; I see every step/device in the process/chain of reproducing sound as a musical instrument in itself. When looked at it in this way, the output of each stage is an 'original' reproduction. So, whatever the influence is of the next stage, the components/process of the next stage will influence the reproduction of its input (previous stage) and this may be measurable/hearable/detectable in any/many way(s), by human or machine The result may be pleasing or dis-pleasing, but there will be a result, and most of the time it will not be neutral/undetectable.
That makes sense for multitracked pop or other artificial recordings, but I think recording an acoustic group of whatever type should be about capturing the sound of the original event, not modifying it. Same goes with reproduction equipment - I'm not looking for just a pleasant sound, I want a system that sounds as close to the real thing as possible.
  Reply With Quote
Old 15th August 2012, 12:30 AM   #516
jcx is offline jcx  United States
diyAudio Member
 
Join Date: Feb 2003
Location: ..
Default always love the "reproduce a real performance" claims

which mics, where? - only binaural dummy heads? crossed cardioid, ambisonics? - what seating position?

virtually all commercial recordings are close miced, most live groups in venues of any size are amplified today - have individual instrument pickup, mic feeds going to a mixing board

studio music production can have performers in different soundproof rooms

many live acoustic performance recording use many mics, some in "listening position" others often flown to capture "ambiance" - mic selection, placement are "artistic choices" - modify recorded sound, capture sound from positions no listener is able to get their ears to

Last edited by jcx; 15th August 2012 at 12:40 AM.
  Reply With Quote
Old 15th August 2012, 12:49 AM   #517
diyAudio Member
 
abraxalito's Avatar
 
Join Date: Sep 2007
Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
Blog Entries: 109
Send a message via MSN to abraxalito Send a message via Yahoo to abraxalito Send a message via Skype™ to abraxalito
Quote:
Originally Posted by owdeo View Post
I agree with the description but my own subjective experience has been that all the "Lin" configuration amps I've heard sound this way.
Curious then why you'd build an NE5532-based pre which is also an opamp of (broadly) the same topology. Here's an experiment to try - swap all those 5532s out for LM6172s and listen again.
__________________
There is surely nothing quite so useless as doing with great efficiency what should not be done at all - Peter Drucker
  Reply With Quote
Old 15th August 2012, 01:41 AM   #518
diyAudio Member
 
Kindhornman's Avatar
 
Join Date: Aug 2012
Location: Los Angeles, California
jcx,
Me thinks you are trying to preach to the choir. You are coming from the position of a pro-audio person rather than the thinking that you can reproduce any live performance and get it to sound exactly like the original. Even being in a live situation if you are sitting in a different position than someone else you are hearing a different blending of the sounds. Coming from the live sound field I can agree with you that it is just unrealistic to have any recording that sounds exactly as the live event. Even to say that a piano should sound a certain way when reproduced goes against the fact that every piano sounds different. Even the same piano played in a different room will sound different and then there is the fact that one person tuning the piano may tune it slightly different than another. All we can really do is make our systems sound as good as we as individuals like. I may like a certain sound and you are looking for something different. What one person says is a sparkly sheen in the upper frequencies another might find annoyingly bright. That is the same reason that earlier Owdeo could not put into words what it was that he thought wasn't right with the preamp in the first place. It isn't something that can be quantified. Or even measured. These arguments can go on for years with no resolution but a lot of opinions about what the truth is.
  Reply With Quote
Old 15th August 2012, 07:46 AM   #519
owdeo is offline owdeo  Australia
diyAudio Member
 
Join Date: Jun 2003
Location: Sydney
Quote:
Originally Posted by jcx View Post
which mics, where? - only binaural dummy heads? crossed cardioid, ambisonics? - what seating position?

virtually all commercial recordings are close miced, most live groups in venues of any size are amplified today - have individual instrument pickup, mic feeds going to a mixing board

studio music production can have performers in different soundproof rooms

many live acoustic performance recording use many mics, some in "listening position" others often flown to capture "ambiance" - mic selection, placement are "artistic choices" - modify recorded sound, capture sound from positions no listener is able to get their ears to
You're talking as though you're some kind of expert in the recording industry - if so I'm glad to have provoked you as I don't like the way you record pianos
  Reply With Quote
Old 15th August 2012, 07:59 AM   #520
owdeo is offline owdeo  Australia
diyAudio Member
 
Join Date: Jun 2003
Location: Sydney
Quote:
Originally Posted by abraxalito View Post
Curious then why you'd build an NE5532-based pre which is also an opamp of (broadly) the same topology. Here's an experiment to try - swap all those 5532s out for LM6172s and listen again.
Good question. I've seen the internal schematic of the 5534 and agree it's broadly similar topology, though it does have nested feedback and a few other things that might make it different. But actually I've only found this "sonic signature" to be the case with power amps of this topology. One of the nicest sounding preamps I've found so far was in fact using something similar to the discrete class A opamp published by none other than Douglas Self in his excellent Small Signal Audio Design book. So I guess I like the sound of this topology at line levels but not as a power amp. Wierd I know.

I just had a look at the LM6172 datasheet - 3MV/us slew rate Doesn't look like one that's likely to be stable as a drop in replacement. Have you had any practical experience with it? What's different about it - is the topology different?
  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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Doug Selfs NE5532 Power Amp. Thoughts anyone ! Mooly Chip Amps 87 15th June 2012 09:08 PM
blameless amp and doug self streetera Solid State 17 16th July 2007 11:06 PM
4th Ed. of Audio Power Amplifier Design Handbook (Doug Self) nickds1 Solid State 4 9th November 2006 01:02 PM
Doug Self Advanced Pre Amplifier PCBs macka Swap Meet 0 9th October 2006 08:41 AM
Help me design pre-amp PS hardcore Tubes / Valves 7 10th November 2004 07:32 AM


New To Site? Need Help?

All times are GMT. The time now is 09:05 PM.


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