Salas DCG3 preamp (line & headphone)

Jump to Latest
#3,181
Johnny Canuck said:
Just doing some final checks before powering up my DCG3 build, and found that I may have made a mistake - can someone please advise?
I have used Takman REY metal film, but through lack of attention have installed 0.25W resistors in about 50% of the positions, rather that 0.5W, which is probably closer in characteristics to the CMF55 recommended in the BOM.
R3 is a 1W resistor.
Question: is it okay to leave the 0.25W pieces in the circuit, or, where is it better to have 0.5W (like R6 perhaps)? 😕
I expect to bias at about 110-120 mA, and gain of about 3.4x.

-Keith-
Click to expand...

Should be fine.

Only R10 (7.5-12R) needs to be 1W
 
#3,183
R6 will dissipate 110mW peak to peak in the unusual event of a sine wave output at 30V peak to peak. So you are technically safe. I just spec fatter resistors when they fit for better thermal inertia if it matters.
 
#3,185
After a long delay from building some Pass clones and my other hobby, I am back on this preamp/headphone amp. Ready to fireup power supply for testing and found a wiring question.

I typically read entire thread, taking notes on points that I needed clarification on and wiring, and this project was no exception. Well, I just found to photos from other members work that I had noted concerning hookup of transformers to power supply boards which dont seem to be the same.

I am using two Antek 50VA transformers, and the dual supply as provided with Teabags kits. (The power supplies, not the transformers). my query is hooking them up to the power supply.

I was reviewing posts #2219 and 2237 of dbls's post which shows his hookups of the dual Anteks https://www.diyaudio.com/forums/ana...cg3-preamp-line-headphone-45.html#post5216332, https://www.diyaudio.com/forums/ana...cg3-preamp-line-headphone-45.html#post5236166 and another post using same at #2881
https://www.diyaudio.com/forums/ana...cg3-preamp-line-headphone-58.html#post5386863 that isnt the same.

I believe the first ones here is correct? (dbis) I guess both worked?

Russellc
 
Last edited:
#3,186
The way the manufacturer shows for that transformer I would have connected the wire colors to the DCSTB's AC-CT-AC connector like this:
 

Attachments

  • Antrek50VA.png
    Antrek50VA.png
    101 KB · Views: 491
#3,187
Yes, that's what I thought. Maybe, well obviously it works the other way, but I would have thought voltages would be off? Maybe not, obviously the method in #2881 works for him. Oh well, I obviously don't know, thats why I asked.

Thanks, much appreciated.

Russellc
 
Last edited:
#3,188
While any two pairs with a mid point mix electrically works, I think that when keeping it as intended by the manufacturer the magnetics are aligned for throwing a smaller field (?). Not that I know much about transformers details either.
 
#3,193
beardman said:
Salas

i can not find the tread where you show some Socket to use with the bc237-40

have you a nummer on those socket...

i will try them again ,,,because i have change speaker and dac

use now Troels Gravesen The Loudspeaker--- and dac from Mirand audio

Best Bjarne
Click to expand...

Hello

Those are called 2.54mm female headers or sockets (example code from company 3M on Mouser: 929870-01-12-30 example on ebay: 10 x 3 Way 2.54mm Single In Line SIL Socket | eBay example on ebay 2: 5pcs 40 Pin 2.54 mm Single Row Round hole Female Pin Header PCB New | eBay)
 

Attachments

  • FHP.jpg
    FHP.jpg
    20.7 KB · Views: 401
  • Q1_Q2 _BC327-40_Altern.jpg
    Q1_Q2 _BC327-40_Altern.jpg
    876.5 KB · Views: 421
#3,197
beardman said:
Thanks Salas
i will buy some from RS parts Denmark

give they good enough connection ?so they can stay in forever
Click to expand...

The transistor legs fit as good as the servo op-amp fits in its socket. At least in those common cheap 2.54mm row sockets I happened to have. But keep the transistor legs short to be rigid. I did not notice any noises etc. from coming loose or oxidized by now.
 
#3,200
OK i try to tell a little about The loudspeaker

it plays very dynamic with ,what i will call big sound,,voices are really good,,easy to hear what they sing...acoustics guitar sound really live and with great dynamic ,,more realistisk than ordinary dome tweeter..
the bas from those 18" is just totally under control,,,it is super to hear drums and bas
guitar
i plays normally concert dvd,,,and sit and listen to well recorded dvd is just marveles

give the feeling that you are there,,,loud and clear,,,

for me it is the best speaker i have used

i have tried many different diy speaker,,,with scanspeak audiotechnology,,peerles and so on
the last speaker i have was gr research ls9 line array (they was also great but not op to The Loudspeaker)

sorry i am not so good in english,,hope you understand a little about it

best bjarne
 
You must log in or register to reply here.
Top Bottom