All DHT Phono Stage

[Salas]

Golden ones on a Steve Bench, almost same like Sheldon's circuit.

 

[brommermartin]

I'm going to build the 3A5 phono stage (Dmitry nizhegorodon)with the SSHV2 power supply's, and the Rod Coleman filament supply's.
Any tips are welcome

 

[Sheldon]

Here's mine: http://www.diyaudio.com/forums/tubes-valves/169428-unholy-alliance-phono-amp.html

Might be some ideas in there. I did end up putting the decoupling 10m caps in the cathode. With my basic CCS they did eliminate a slight hum. With a Coleman style reg, probably not necessary.

Sheldon

 

[211hojbjerg]

Hi dht,
You should check out Thoms Meyer blog, wher he have designed a all DHT system with LCR riia. Using 841 and 801 in the stage before the LCR riia.
Best regards
Karsten

 

[brommermartin]

Thanks sheldon I will build the phono stage like your schematic but
With Rod Coleman filament units and the Salas sshv2 units.
Thomas makes very nice amps but with a different price tag then this project.
He recommended the use of the 10Y driver for my 45 amp , the sound of the amp is amazing

 

[Sheldon]

I will build the phono stage like your schematic but With Rod Coleman filament units and the Salas sshv2 units.

Nice. Keep us posted. Do you intend to use a gyrator or ccs on the output stage, or resistor loaded. If your next stage has an input impedance around 100k or more, resistor load will do.

Sheldon

 

[brommermartin]

I will go for resistor loading the last stage as my 4p1l preamp has a potmeter of 100k

 

[brommermartin]

The phono amp is playing now for a couple of hours and the sound is very nice
No microfonics but only a small hum, that's likely because there is no housing for screening.
The sound stage is deep with good dynamics

 

[Sheldon]

Nice!

 

[kevinkr]

Mount the supplies in one box and the phono stage itself in another and it will be absolutely silent I'd wager.. Do locate the Coleman CCS in the box with the phono stage, the SSHV2 could go in either as long as the DC feeding it is quiet. I use an SSHV2 in my dac where it is located in the dac chassis rather than the psu chassis and it works well.

 

[Sheldon]

Mount the supplies in one box and the phono stage itself in another and it will be absolutely silent I'd wager.. Do locate the Coleman CCS in the box with the phono stage, the SSHV2 could go in either as long as the DC feeding it is quiet. I use an SSHV2 in my dac where it is located in the dac chassis rather than the psu chassis and it works well.

That was my experience. The HV shunt supplies and filament regulators are in the amp chassis. The raw supplies (transformer and LC/RC filters) in a separate chassis. Care taken with star grounds. No hum.

Sheldon

 

[mogliaa]

The phono amp is playing now for a couple of hours and the sound is very nice
No microfonics but only a small hum, that's likely because there is no housing for screening.
The sound stage is deep with good dynamics

Hi Martin,
Congrats, it looks superb. What phono preamp did you have before and what differences did you notice in sound? What is your final stage prior to the 4P1L? Is a gyrator one or a cathode follower?

I second the two split chassis for this one.

A great project to get embarked on (oh no another one!)

Cheers
Ale

 

[brommermartin]

Hello Ale

My other phono amp is the Phono Dude ,this design is well known in de Dutch diy scene. The 3a5 phono amp is better in details and a deeper and wider sound stage.
At the moment the last stage of the 3A5 phono is resistor loaded, but I will
try the mu stage
I have used the K40y couple caps and a 0,47uf vitamin Q at the output , first I will let the amp play for a week or so to settle.