Attenuator for Passive pre amp, best sounding solution - Page 3 - diyAudio
Go Back   Home > Forums > Source & Line > Analog Line Level

Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

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 1st May 2014, 08:09 PM   #21
irribeo is offline irribeo  Netherlands
diyAudio Member
 
Join Date: Apr 2013
Default or another inductive based on elma

happen to see build on dutch forum with this one

Tribute - The final word in audiotransformers

+/-435 euro, built to order (+/-3 months waiting)
Attached Images
File Type: gif inductive_vol_control_2.gif (71.9 KB, 379 views)
File Type: gif inductive_vol_control_3.gif (40.1 KB, 371 views)
File Type: gif inductive_vol_control_1.gif (31.1 KB, 371 views)
  Reply With Quote
Old 1st May 2014, 08:19 PM   #22
diyAudio Member
 
merlin el mago's Avatar
 
Join Date: Sep 2009
Location: Catalonia - Europe
Looking for the best I will used Shallco in place of Elma.
  Reply With Quote
Old 3rd May 2014, 11:35 AM   #23
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
From reading, I know both of you to be talented designers. Lets not make a question of choice turn into anything else. There are plenty of examples for both cases and preferences. At a high quality level, we are talking about flavors, not quality. I have heard amps with outstanding numbers that suck and amps that are "musically" crafted that sucked and needed better engineering. Tomato vs tomato.
__________________
...Shape the sound , Man!
  Reply With Quote
Old 3rd May 2014, 11:41 AM   #24
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007


I've deleted a couple of posts. Lets keep personal feeling out of this. Benefit of the doubt this time... that this was just a genuine misunderstanding.
__________________
-------------------------------------------------------
Installing and using LTspice. From beginner to advanced.
  Reply With Quote
Old 5th May 2014, 11:41 AM   #25
UMarcus is offline UMarcus  Germany
diyAudio Member
 
Join Date: Mar 2011
Location: Black Forest, Germany
Hi Guys,
many thanks for that useful technical information and suggestion.

There remain some open questions about the transformer solution in my mind

I want to attenuate balanced signals, will the Auto-Transformer work ?

If a transformer is used to attenuate, what happens with the small DC Offset on the input ? I guess it will not transferred to the Output ? So it is possible to keep the Couple C out of the system ?

Thanks
Regards
Marcus
  Reply With Quote
Old 5th May 2014, 11:53 AM   #26
diyAudio Member
 
merlin el mago's Avatar
 
Join Date: Sep 2009
Location: Catalonia - Europe
For balanced you need four auto-transformers.
  Reply With Quote
Old 5th May 2014, 12:25 PM   #27
UMarcus is offline UMarcus  Germany
diyAudio Member
 
Join Date: Mar 2011
Location: Black Forest, Germany
Quote:
Originally Posted by merlin el mago View Post
For balanced you need four auto-transformers.
Oh.. ok, that's heavy load of wallet

What is with 'normal' wound att. transformers like

SOWTER ATTENUATOR TRANSFORMERS TVC VOLUME CONTROL

Regards
Marcus
  Reply With Quote
Old 5th May 2014, 12:50 PM   #28
DUG is offline DUG  Canada
diyAudio Member
 
Join Date: Jan 2003
Location: mississauga ontario canada
Quote:
Originally Posted by merlin el mago View Post
For balanced you need four auto-transformers.
If they are designed for single ended, yes.

If they were designed for balanced use that would not be the case.

(still expensive IMHO)

__________________
Doug We are all learning...we can all help
"You can't stop the signal, Mal. Everything goes somewhere..."
  Reply With Quote
Old 5th May 2014, 02:34 PM   #29
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
DC offset is a problem for certain types of trafo - mumetal cored without an air gap are the most sensitive. Coupling caps recommended for these. I wind my own trafos on ferrite (SMPSU style) cores, they're only expensive in terms of time spent as the parts (enamelled copper wire, cores) are very cheap. They do have one disadvantage over the more expensive metal-cored ones - their primary inductance tends to be a bit on the low side, whether this is a problem in practice depends on the driving circuit. I haven't found it to be anywhere near a show-stopper and I air-gap mine which makes matters worse...
__________________
Seek not the favour of the multitude...rather the testimony of few. And number not voices, but weigh them. - Kant
The capacity for impartial observation is commonly called 'cynicism' by those who lack it.
  Reply With Quote
Old 5th May 2014, 06:43 PM   #30
UMarcus is offline UMarcus  Germany
diyAudio Member
 
Join Date: Mar 2011
Location: Black Forest, Germany
Quote:
Originally Posted by abraxalito View Post
DC offset is a problem for certain types of trafo - mumetal cored without an air gap are the most sensitive. Coupling caps recommended for these. I wind my own trafos on ferrite (SMPSU style) cores, they're only expensive in terms of time spent as the parts (enamelled copper wire, cores) are very cheap. They do have one disadvantage over the more expensive metal-cored ones - their primary inductance tends to be a bit on the low side, whether this is a problem in practice depends on the driving circuit. I haven't found it to be anywhere near a show-stopper and I air-gap mine which makes matters worse...
Thanks for you explanation. Could you give more details to understand what are the problem of DC offset ? Magnetization ? How many DC offset usually a problem ?
But at least the DC offset not tranfered to the output, or i'm wrong ?
  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
Best-Sounding RC Attenuator & Source Selection System SRMcGee Analog Line Level 0 13th January 2014 09:50 PM
Value of Stepped Attenuator for Passive Amp. xtaljo Analog Line Level 7 22nd October 2012 04:13 PM
Attenuator for passive pre (LEAK ST 20) vincula Tubes / Valves 9 11th October 2012 06:03 PM
Here's my DIY passive attenuator / pre / integrated DAC audiogeekess Analog Line Level 0 7th December 2011 12:22 PM
FS: Dact CT2 10K-2 Stereo Attenuator plus DIY passive pre enclosure GaryAR Swap Meet 6 21st December 2006 08:28 AM


New To Site? Need Help?

All times are GMT. The time now is 06:16 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