Salas DCG3 preamp (line & headphone)

[Theodosis O.]

What's the plan? To make an extra preamp for another system, to add a headphones preamp for this system, or to only substitute the tube line preamp section of the Viva amp?

The plan is:
LDR Volume control -> Salas DCG3 -> FirstOne Large with 2x3KVA Hypex SMPS

I would prefer to put all these in a single box in order to avoid the extra interconnect cable,
The problem in this case is the heat.

But I think now that DCG3 is great also as a buffer. Maybe will lower the gain and keep it in front of Viva.

 

[Salas]

Is it that the Single ended 845 tubes Viva amp is not that powerful for those big tower (Sonus Faber Amati?) speakers? Or you are also trying another new system altogether? Since DCG3 drives cables with ease, in my opinion better keep it separate with very good shielded transformers of its own so to can combine it as an independent preamp with any future idea.

 

[Salas]

Hi Salas ,what is the absolute minimal power rating for the resistors with the DCG3?. I accidentally got some lower power rating of 1/8w and 1/10W for some resistors? Don't know how i got there . Must be over excited as board have arrived. Thanks.
Quan

R10 no less than 1/2W
R6 no less than 1/4W

 

[quan]

R10 no less than 1/2W
R6 no less than 1/4W

Thanks.
Quan

 

[MagicBus]

Just arrived! Not bad timing after all... I had to finish a guitar amp for my little nephew meanwhile. I wish the best for the new year to everyone

 

[AIM65]

Back from vacation and found the parcel in my mail box !
Very nice PCB, premium quality.

Thank you Tea Bag and Salas for GB and design.

 

[Salas]

Alright

 

[Theodosis O.]

Is it that the Single ended 845 tubes Viva amp is not that powerful for those big tower (Sonus Faber Amati?) speakers? Or you are also trying another new system altogether?

No, I am very satisfied with the sound of Viva up to 95 DB.
Guess room treatment is needed primarily to go above this level.
Yes, I am just trying a transistor amp.

 

[MagicBus]

I've started assembling. Those PCBs are a dream! I need to ask a couple of things;

I'm building two DCG3 boards (balanced) and one DCSTB board. Each stereo board will be powered by one psu rail. I think channel separation will be OK but what about current consumption? Is it safe to bias at 150 mA? Is it a compromise to stay at 100 mA wrt sound quality rather than driving ability?

Also, my system is quite idiosyncratic... Preamp actually means a compined DAC analogue output and a line stage together thus, gain is never high enough! DCG3 will be set for 4x - 1k5 isn't it ? I have used line stage with this gain and I know it will do but I would like to know if there is posibility to go higher...

 

[lykkedk]

I've started assembling. Those PCBs are a dream! I need to ask a couple of things;

I'm building two DCG3 boards (balanced) and one DCSTB board. Each stereo board will be powered by one psu rail. I think channel separation will be OK but what about current consumption? Is it safe to bias at 150 mA? Is it a compromise to stay at 100 mA wrt sound quality rather than driving ability?

Also, my system is quite idiosyncratic... Preamp actually means a compined DAC analogue output and a line stage together thus, gain is never high enough! DCG3 will be set for 4x - 1k5 isn't it ? I have used line stage with this gain and I know it will do but I would like to know if there is posibility to go higher...

I am not expert; but one PSU get's rather hot, by bias at 100mA when used for stereo setup on one DCG3 board (I did try this when building)... So if you will bias it at 150mA i think you need bigger heatsinks on DCSTB.

Jesper.

 

[nashbap]

I am not expert; but one PSU get's rather hot, by bias at 100mA when used for stereo setup on one DCG3 board (I did try this when building)... So if you will bias it at 150mA i think you need bigger heatsinks on DCSTB.

Jesper.

Jesper when you tried this was it with a 1inch heatsink or 1 1/2?
nash

 

[lykkedk]

Jesper when you tried this was it with a 1inch heatsink or 1 1/2?
nash

The 1 1/2 inch ones...

Jesper.

 

[MagicBus]

Thanks Jesper! If heat is the only issue I can go for bigger than 2" and test it.

 

[nashbap]

Thanks Jesper! If heat is the only issue I can go for bigger than 2" and test it.

Wakefield 647-25ABPE These are 2.5in.
Let me know how you make out since I am building a similar configuration to yours.
nash

 

[MagicBus]

Thanks Nash. I'll report progress...

 

[Salas]

I've started assembling. Those PCBs are a dream! I need to ask a couple of things;

I'm building two DCG3 boards (balanced) and one DCSTB board. Each stereo board will be powered by one psu rail. I think channel separation will be OK but what about current consumption? Is it safe to bias at 150 mA? Is it a compromise to stay at 100 mA wrt sound quality rather than driving ability?

Also, my system is quite idiosyncratic... Preamp actually means a compined DAC analogue output and a line stage together thus, gain is never high enough! DCG3 will be set for 4x - 1k5 isn't it ? I have used line stage with this gain and I know it will do but I would like to know if there is posibility to go higher...

150mA output stage bias will make no THD difference to 100mA for loads >60Ω

6x gain can be done with R6=2.5KΩ

 

[MagicBus]

Thanks Salas! I'll test this.

 

[Theodosis O.]

150mA output stage bias will make no THD difference to 100mA for loads >60Ω

6x gain can be done with R6=2.5KΩ

So the ideal for preamp is 100 mA ?

 

[Salas]

Objectively yes for line preamp and easy Ohms headphones

 

[NickBRN]

So the ideal for preamp is 100 mA ?

Objectively yes for line preamp and easy Ohms headphones

So just for preamp use, over 100 mA means no any sonic privileges ...?