New Doug Self pre-amp design... - Page 43 - 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 29th June 2012, 02:44 PM   #421
redjr is offline redjr  United States
diyAudio Member
 
Join Date: May 2011
Location: Danbury, CT
Quote:
Originally Posted by sandyK View Post
Don't forget that these home brew IDC cables can also cause all kinds of funny things to happen with DACs too.

Regards
Alex
Sandy,

Is there a potential problem in using standard ribbon cable for this pre-amp solution? It is being suggested by Elektor or Doug Self. Or, should I attempt to weave 10 individual wires from the pins of the sockets. The former suggestion seems to be the easiest, but maybe not the best in terms of sonics? What issues should I be concerned with when using ribbon cable with a DAC?
  Reply With Quote
Old 29th June 2012, 02:59 PM   #422
Bonsai is offline Bonsai  Taiwan
diyAudio Member
 
Bonsai's Avatar
 
Join Date: Jul 2003
Location: Taipei, Taiwan
Quote"It's no good listening after immediately swapping parts because you are not in the right frame of mind""

It's called expectation bias.
__________________
bonsai
Amplifier Design and Construction for MUSIC! http://hifisonix.com/
  Reply With Quote
Old 29th June 2012, 03:11 PM   #423
diyAudio Member
 
Nico Ras's Avatar
 
Join Date: Nov 2005
Location: East Coast of South Africa
Quote:
Originally Posted by owdeo View Post
Me too, the acoustic ones make a much nicer sound even though the electric ones are probably considered blameless now

Thanks Mooly, I'm 100% with you on all that
Which of the acoustic pianos sound the most like a real piano? If measured against the first piano ever made then all successive pianos are distorted.
__________________
Kindest regards
Nico
  Reply With Quote
Old 29th June 2012, 06:08 PM   #424
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Quote:
Originally Posted by owdeo View Post
Me too, the acoustic ones make a much nicer sound even though the electric ones are probably considered blameless now
Nice one


Quote:
Originally Posted by Bonsai View Post
Quote"It's no good listening after immediately swapping parts because you are not in the right frame of mind""

It's called expectation bias.
It is indeed
__________________
-------------------------------------------------------
Installing and using LTspice. From beginner to advanced.
  Reply With Quote
Old 30th June 2012, 12:22 AM   #425
owdeo is offline owdeo  Australia
diyAudio Member
 
Join Date: Jun 2003
Location: Sydney
Quote:
Originally Posted by redjr View Post
Is there a potential problem in using standard ribbon cable for this pre-amp solution? It is being suggested by Elektor or Doug Self. Or, should I attempt to weave 10 individual wires from the pins of the sockets. The former suggestion seems to be the easiest, but maybe not the best in terms of sonics? What issues should I be concerned with when using ribbon cable with a DAC?
Ignore that redjr, Alex was having a dig about another unlrelated project I was discussing with him offline

The ribbon cable in the 2012 preamp is only used for control signals to switch the relays so can't affect SQ - you'll know if there's a problem if your input switching starts going haywire.

For the signal connections in your preamp between the boards I would suggest using sheilded audio cable to minimise induced hum/noise from the power transformer and surrounding environment. Don't use ribbon cable!
  Reply With Quote
Old 30th June 2012, 01:07 AM   #426
Bonsai is offline Bonsai  Taiwan
diyAudio Member
 
Bonsai's Avatar
 
Join Date: Jul 2003
Location: Taipei, Taiwan
If you are using headphones to do comparative listening tests, try a 47 to 100 Ohm resistor in series with the headphones.
__________________
bonsai
Amplifier Design and Construction for MUSIC! http://hifisonix.com/
  Reply With Quote
Old 30th June 2012, 04:58 AM   #427
redjr is offline redjr  United States
diyAudio Member
 
Join Date: May 2011
Location: Danbury, CT
Quote:
Originally Posted by owdeo View Post
Ignore that redjr, Alex was having a dig about another unlrelated project I was discussing with him offline

The ribbon cable in the 2012 preamp is only used for control signals to switch the relays so can't affect SQ - you'll know if there's a problem if your input switching starts going haywire.

For the signal connections in your preamp between the boards I would suggest using sheilded audio cable to minimise induced hum/noise from the power transformer and surrounding environment. Don't use ribbon cable!
OK. I haven't decided for sure what type of cable I'm going to use for the internal signal interconnects. I'm just trying to sort through the various 2, 3 and 4-pin headers on all the boards and how the puzzle fits together. I think I will draw up a block diagram of this beast since there are so many boards, and how they all connect was not laid out all that well in the article. Also it seems Elector chose to use 4-pin header on several of the boards when 3 pin headers would have sufficed. The center two pins seem to always be tied together as a ground. So the the extra center pin is redundant and is not required. Where is the KISS approach here!

It's late here so I'm going to bed.
  Reply With Quote
Old 1st July 2012, 12:27 AM   #428
owdeo is offline owdeo  Australia
diyAudio Member
 
Join Date: Jun 2003
Location: Sydney
Somehow I don't think the KISS principle is what this design is all about

I know it seems redundant but there may have been a reason for using a 4 pin header when a 3 pin would do: once you start trying to solder or crimp shielded cable braid into those pins for the 0.1" header sockets you'll see that soldering two braids onto one earth pin can easily make it too fat to fit into the connector housing in which the socket pins are housed. I'd rather have the 4 pins, one for each wire.
  Reply With Quote
Old 4th July 2012, 01:08 PM   #429
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
At what frequency is that ?
Crossover shows more at higher frequencies.
  Reply With Quote
Old 4th July 2012, 02:04 PM   #430
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
It may run out of class A in certain conditions but the high feedback will erode most of it so measurements will still be clean.
Some time ago i measured how much class A certain Opamps have. You can put a low value resistor, say 50 Ohm, from the output to ground. Then you put say 10 Ohm resistors into the voltage feed to Pin 4 and Pin 7. You then increase the input voltage of a 1kHz signal ( can be 10kHz or higher ) until the current goes up that flows into the Opamp from the PSU. The 10 Ohm resistors function as sensors by measuring the voltage over them. I would say that the LME49710 has around 2mA class A. When you drive a 600 Ohm load it will leave class A at 1,2V.
  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 08:08 PM
blameless amp and doug self streetera Solid State 17 16th July 2007 10:06 PM
4th Ed. of Audio Power Amplifier Design Handbook (Doug Self) nickds1 Solid State 4 9th November 2006 12:02 PM
Doug Self Advanced Pre Amplifier PCBs macka Swap Meet 0 9th October 2006 07:41 AM
Help me design pre-amp PS hardcore Tubes / Valves 7 10th November 2004 06:32 AM


New To Site? Need Help?

All times are GMT. The time now is 03:46 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