Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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

Salas DCG3 preamp (line & headphone)
Salas DCG3 preamp (line & headphone)
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 16th May 2019, 07:01 PM   #3831
Tea-Bag is offline Tea-Bag  United States
not politcally affiliated
diyAudio Member
 
Tea-Bag's Avatar
 
Join Date: Feb 2006
Location: Kennebunk
Salas DCG3 preamp (line & headphone)
I believe 500R is lowest possible value. My lazy man test would be to put another 1K on R6 to get to 500R to see. Salas would have to validate that is lowest possible value.
__________________
Salas Boards GB 2019 #1 CLOSED boards On Order | M2C Boards, PS and transformers Available PM | Sony VFET CSX2 AL boards In Stock
  Reply With Quote
Old 16th May 2019, 07:03 PM   #3832
Joschl is offline Joschl  Germany
diyAudio Member
 
Joschl's Avatar
 
Join Date: Dec 2005
Location: Ruhrgebiet
You can hang a resistor from the source input to the potentiometer input. Choose R same as volume potentiometer. This creates sort of a virtual potentiometer with double the input resistance and only half way can be put out via the wiper ( middle pin). The virtual pot turns only half while your knob turns full. And easily reversible tooSalas DCG3 preamp (line & headphone)
  Reply With Quote
Old 16th May 2019, 09:55 PM   #3833
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Salas DCG3 preamp (line & headphone)
Quote:
Originally Posted by killie99 View Post
I now have the DCG3 hooked up to my main system, it’s super quiet, not a bit of hiss or hum from the speakers. I do however have a pretty major problem, I have just got waaaaaaaaaaayyyyyyyyyyyyy too much gain! I’m currently using just the power amp section of my Perreaux Eloquence 250i and I can use to about 8 o’clock on the pot and it’s very loud. Checked the manual and I have 28.8dB of gain in the power amp - how low can I take the gain on the dcg3 (currently set to 3 with a 1k) without causing any issues?. Long term plan is to get a different amp but what’s the best approach to reduce the gain in the time being?
Although an input voltage divider is possible, it's better to fix the gain lower via R6. Not to narrow the bandwidth with inevitably higher source impedance. Since this circuit isn't input buffered. Can go down to 500R R6 as mentioned. The amplifier's gain is high enough, maybe the speakers are sensitive enough also? Anyways, when in a loud combination the background is still reported quiet after adding 3x, that surely points to a good preamp build.
  Reply With Quote
Old 16th May 2019, 10:07 PM   #3834
killie99 is offline killie99
diyAudio Member
 
Join Date: May 2011
I'll try and source some Dale 499 ohm in the UK to lower the gain. A quick google pops these up, Salas can you confirm these are what I need? Vishay Dale CMF55 resistor 1% 50ppm 499ohm - Audiophonics

I also have 4 BC327-40 all with 499-502 hfe so I'll pop them in as well.
  Reply With Quote
Old 16th May 2019, 10:17 PM   #3835
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Salas DCG3 preamp (line & headphone)
Those resistors are fine, same as the kit's others. That change will bring your gain down to 2/3 of what's now. You will probably like the alternative current mirror transistors too.
  Reply With Quote
Old 19th May 2019, 09:24 AM   #3836
shattered_dream is offline shattered_dream  Germany
diyAudio Member
 
Join Date: Dec 2009
Hmmm do I need insulation foil for the heat sink of the dcstb?
  Reply With Quote
Old 19th May 2019, 12:58 PM   #3837
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Salas DCG3 preamp (line & headphone)
You need insulation pads and insulation grommets for each MOSFET to that sink. The sink itself can be fixed non insulated to the chassis.
  Reply With Quote
Old 29th May 2019, 06:07 PM   #3838
shattered_dream is offline shattered_dream  Germany
diyAudio Member
 
Join Date: Dec 2009
Hmmm what would you recommend... The Bc560 or the Bc327-40?
I'm not sure until now.... Since there were both in my package
  Reply With Quote
Old 29th May 2019, 06:58 PM   #3839
vgeorge is offline vgeorge  Greece
diyAudio Member
 
vgeorge's Avatar
 
Join Date: Mar 2004
Location: poros island
Salas DCG3 preamp (line & headphone)
Better use BC-327-40
__________________
"Without deviations from the norm, progress is not possible" - Frank Zappa
  Reply With Quote
Old 29th May 2019, 07:18 PM   #3840
beardman is offline beardman  Denmark
diyAudio Member
 
Join Date: Jan 2005
Location: a littlee town in western denmark
I have tried BC-327-40 2 times

but prefer in my setup BC560

so try both and listen carefully,,,,BC 327 is more mellow here
  Reply With Quote

Reply


Salas DCG3 preamp (line & headphone)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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
FS: Pass VFET 2 essential+supplemental kit and Salas DCG3 kit 32y0 Swap Meet 3 16th April 2018 05:22 AM
FS : Salas DCG3 pinnocchio Swap Meet 2 9th January 2018 10:32 PM
FS: 2x Salas DCG3 and DCSTB complete kits bvtrinh Swap Meet 5 26th October 2017 11:29 PM
WTB Salas DCG3 pcb or kit savvas Swap Meet 0 8th February 2017 10:50 AM
Using a line preamp to drive headphone ginetto61 Solid State 25 6th May 2015 06:19 PM


New To Site? Need Help?

All times are GMT. The time now is 11:52 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki