Salas DCG3 preamp (line & headphone)

Dear Salas, thank you very much for this project, I've been using your preamplifier since June 2017 and I love it, it surprises me how much detail it gives me, the bass is deep and the voices are like a very fine grain. Today I use it with a headset sennheiser hd555, but I would like to change it, I anticipated spending about 300 euros to get a good headset closed, because I listen to music alongside my wife and I like high volumes and with headphones open I realize to disturb. I wish they were well balanced, easy to bag but I can not choose: I need a hand. Thank you so much for your help.
 

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That's a very nice build. Congratulations. Have you looked in the Oppo PM-3? OPPO PM-3 Closed-Back Planar Magnetic Headphones

For more affordable dynamic the AKG K553 MKII maybe. K553 MKII | Closed-back studio headphones
Dear Salas, thank you for the suggestions, I have tried to find the Oppo but is very expensive and here in Italy there is only one who sell it, also the akg seems to be very hard to find. Do you have some other good choice? Sorry if I do all theese request but I like your work and I like your opinion. Thank you in advance.
 
I have! And I love it!

It's open sounding without ever beeing harsh and the soundstage is just excellent! Sure invites me to go above my normal listnening volume.:p
No hiss or hum too :)

Again, thank you so much for this great circuit!;)

I'm looking at doing the same combo as you. I seen ZDRs LDR also. Congrads on your builds, tha js for sharing and feel free to upload more pictures ��
 
I'm looking at doing the same combo as you. I seen ZDRs LDR also. Congrads on your builds, tha js for sharing and feel free to upload more pictures ��
Thank you Maverick2020!
It's absolutley a lovley combo with the LDR, highly recommended! Really in love with this pre in my setup. ;)

Iv'e seen the newest pcbs by ZDR are black, so they will even match the internals :)

I don't know what more pictures you want, I actually have taken a lot when building this(as I usually do when building things).
You can see the lot of it the google album here:
Salas DCG3 by Twst - Google Photos

Attached finished pictures with knobs, feets and even the top on :cool:
 

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Thank you Maverick2020!
It's absolutley a lovley combo with the LDR, highly recommended! Really in love with this pre in my setup. ;)

Iv'e seen the newest pcbs by ZDR are black, so they will even match the internals :)

I don't know what more pictures you want, I actually have taken a lot when building this(as I usually do when building things).
You can see the lot of it the google album here:
Salas DCG3 by Twst - Google Photos

Attached finished pictures with knobs, feets and even the top on :cool:

Your a good man. I will check it all out and see what I'm going to do. I've already been in touch with ZDR for his stuff. Just thinking what I will do for the housing.
 
diyAudio Chief Moderator
Joined 2002
Paid Member
Thank you Maverick2020!
It's absolutley a lovley combo with the LDR, highly recommended! Really in love with this pre in my setup. ;)

Iv'e seen the newest pcbs by ZDR are black, so they will even match the internals :)

I don't know what more pictures you want, I actually have taken a lot when building this(as I usually do when building things).
You can see the lot of it the google album here:
Salas DCG3 by Twst - Google Photos

Attached finished pictures with knobs, feets and even the top on :cool:

Nice building steps pictures and great final looks :up:
 
Managed to score a full kit from Swap Meet, so things are looking up.

The plan is for sure to get proper dual trannies in the future, but i have a 120VA 2x15V trafo lying around, and i seem to recall reading earlier in this thread someone using a similar setup, and it being borderline for the DCSTB, but that it could work at least for initial testing.

I also seem to recall reading that when using a single trannie, one should also just use a single DCSTB, is that a correct assessment?

Will i need to alter the Vrefs created by the LEDs any? I thought i had read about this in the thread, but i'm unable to find it. Guess there is only one solution, read the whole thing. :)

I think i'll forego the DCB1 entirely, and just feed my Fetzilla from the DCG3, with one of those headphone outputs which re-route the signal when i plug them in, if those are still around. I might set the DCG3 up for a gain of 2, or possibly even do switchable gain.

Headphones are Sennheiser 58X from Massdrop(Z=150). Surely not the be-all, end-all of cans, but should be a step up from my Yamaha RH-5Ma i used to have before misplacing them.

The kit i bought comes with a complete setup for i-select as well, which i hadn't planned on using originally, but hey, i'll take it. ;)

I really liked the HAHN potted ones you used Salas, but i can't seem to find those quite big enough for the DCSTB, i did read recommendations for other stuff, right now it's leaning towards Toroidy shielded toroids. Would love to try some R-cores, they sure do look pretty.
 
Hi everyone!

I am slowly buying components for DCG-3.
Bought four uPA68HA and they are very good matched between piece.
All are grade K, mostly ~4.40 Idss.
Can I use them in DCG-3?
Got even two very close between left and right channels.
One Idss is 4.47/4.46 and second is 4.43/4.40

And a second question.
Should IRF9610 be matched in any way?
 
diyAudio Chief Moderator
Joined 2002
Paid Member
@Kris0603

You can use a 15-0-15V Tx for starting with but do end up with 18-0-18V double 50VA ones. The PSU system works more optimally with those. With only a single Tx use a single PSU section for both channels rails. Until you will be better equipped.

Toroidy magnetically shielded TXs are much better products in some ways than off the shelf potted ones even when adequately sized. No doubt. Since they are tailor made you can even ask for 17-0-17V secondaries to lessen the heat on the DCSTB sinks.

The Vrefs normally need no changes for additional voltage from any higher value RxJ Ryj. Nobody chanced on weak Ledbars yet.
Details about the PSU's Vrefs manipulation are in the PDF's DCSTB section.

Since you will use headphones also, its better you bias the output stage high. The ones you now got are easy but at a point you may wanna hook up some below 80 Ohm cans, why not be prepared.
 
One more DCG3 done!

Hi all,

And...done! With some short listening sessions very pleased so far. Biased to 100mA for HD6XX cans but sounds allright too on my ATH-MSR7.

The PSU heatsinks get pretty warm after 1-2 hours (top cover ON) but still touchable. Amp heatsink gets barely warm.

Steef
 

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