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 2nd June 2020, 01:46 PM   #4711
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Salas DCG3 preamp (line & headphone)
Quote:
Originally Posted by 66deg View Post
Thanks, I will put in the 3x and sort the amp situation out after building The Loudspeaker.
Your help and advice are much appreciated.
A miniDSP digital crossover box can also equalize gain between different active branches to amps. On top of customizing curves and delays for a very versatile speaker optimization approach.
  Reply With Quote
Old 2nd June 2020, 02:02 PM   #4712
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Salas DCG3 preamp (line & headphone)
In any case 29dB gain is 28 times. To achieve that, R6 should be near 13.5k. Two 27k in parallel are equivalent to that. I don't know if there could be any practical oddities, we never tried it up there, but LT Spice shows it working. THD will be worse than in normal gain builds when pushed for level, especially for full blast near rail to rail output swing.
  Reply With Quote
Old 2nd June 2020, 02:05 PM   #4713
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Salas DCG3 preamp (line & headphone)
Quote:
Originally Posted by Rothor View Post
Sounds Good, and Iím happy with that! Thanks again for helping all of us getting back on track and learning by doing it! Itís highly appreciated!
  Reply With Quote
Old 2nd June 2020, 07:21 PM   #4714
r_jik45 is offline r_jik45  France
diyAudio Member
 
Join Date: May 2005
Location: Fr, Jpn
DCSTB units got soldered and connected, here are the outputs:
-17.71 / 17.69
-17.66 / 17.65

Heatsinks remain 'cold', maybe because there is no load yet.
  Reply With Quote
Old 2nd June 2020, 07:26 PM   #4715
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Salas DCG3 preamp (line & headphone)
Yes. Its series pass type. Needs something to pull current through it. It now only burns little mA on its 3.3k output bleeders as loads.
  Reply With Quote
Old 3rd June 2020, 12:32 PM   #4716
66deg is offline 66deg  United Kingdom
diyAudio Member
 
Join Date: Apr 2016
Location: Provence
I have had a quick read about the mini DSP and it looks very interesting , as I have no WAF considerations in the workshop one power amp per driver shouldn't be a problem.


Progress is being made on the board but I would just like to check orientation of J1/J2 with the printed side towards the printing on the board? image below.

Thanks.
Attached Images
File Type: jpg IMG_1468.jpg (580.8 KB, 168 views)
File Type: jpg IMG_1467.jpg (448.0 KB, 157 views)
  Reply With Quote
Old 3rd June 2020, 12:50 PM   #4717
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Salas DCG3 preamp (line & headphone)
Orientation is fine. You can't go wrong with this uPA68 inline package, it mirrors itself correctly in anyway you flip it.
  Reply With Quote
Old 3rd June 2020, 06:07 PM   #4718
Jim50hertz is offline Jim50hertz  United Kingdom
diyAudio Member
 
Join Date: Jul 2013
Salas, just read of the BC327-40 mod. How many should I buy to sort through? Datasheet suggests an average hfe of 400, max 630, making a need for around 500 hfe on the upper end of specs.

Also, I’ve searched and can’t find the answer but, if I drop the gain to 2, how do I do it (r6?) and will it compromise the sound of my unit, which I’ve been very happy with.

I’m building the Pass DIY VFet amp and will be running 99db drivers in a TQWT so the gain in the DCG3 may be too much.
  Reply With Quote
Old 3rd June 2020, 07:23 PM   #4719
r_jik45 is offline r_jik45  France
diyAudio Member
 
Join Date: May 2005
Location: Fr, Jpn
@66deg,
You already put the op-amp in place?
Maybe you can check again the guide:
Quote:
7. DC offset
If all is ok and warm, short the signal inputs and measure the DC offset across each line output. It may read many mV at first because VR1's half point starts at a relatively high value for the purpose. Tweak VR1 per channel to the narrower range of hovering mV around zero DC you can. Don't expect it to stop moving about because it will not. Shut down.
Measure that the rails are down to zero volts first. Put the op-amp in the socket with its dot oriented towards the relay. Power up. A minute after the click verify that the DC offset is very low in mV. It may prove less than 1 mV even but not all op-amps are doing the same.
  Reply With Quote
Old 3rd June 2020, 07:44 PM   #4720
66deg is offline 66deg  United Kingdom
diyAudio Member
 
Join Date: Apr 2016
Location: Provence
Thanks, I had a read over the guide earlier today and spotted the very same mistake, appreciate you mentioning it though as I have on occasion missed things just like that.
 

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 08:07 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Copyright ©1999-2020 diyAudio
Wiki