Best line stage tube?

[M Gregg]

Allen,

I assume Pi filters didn't help?

Regards
M. Gregg

 

[grufti]

This looks pretty decent to me:

http://www.diyaudio.com/forums/power-supplies/159705-when-you-need-15vdc-have-only-one-pole.html

Make sure you're not getting far more noise from the DC/DC box than you want. I've yet to find a quiet one, and most of the noise is highish F and spiky, so hard to ignore.

Regards, Allen

 

[Michael Koster]

Hi,

Just a thought regards the heater having to be floated on the HT supply rail when I only want to bring DC into the line stage from an existing circuit!

So I am going to try a DC to DC converter that has 1.6KV DC isolation to supply the SRPP ECC88 heaters and float them using HT connected to DC converter output! Should be interesting!

Regards
M. Gregg

Converter powering heaters needs to be over-rated to handle the cold inrush current of the heaters-- or use a higher voltage DC/DC output plus CCS... I had some that thought they were driving a short circuit and wouldn't start up.

 

[Allen Wright]

Allen,

I assume Pi filters didn't help?

Regards
M. Gregg

They most likely would, but IMO, the whole point of using a DC/DC converter box is circuit simplicity. Having to add filters makes it far less than simple.

Regards, Allen

 

[agent.5]

They most likely would, but IMO, the whole point of using a DC/DC converter box is circuit simplicity. Having to add filters makes it far less than simple.

Regards, Allen

What about a filter likes this? Has anyone played with them?

RAM Ripple Attenuator Module / Vicor Power Filters

 

[M Gregg]

Hi,

The RAM filters look interesting!
Does anyone know if I series two 6.3V heaters (12.6V). What is the minimum voltage I can run them at without damage?

Regards
M. Gregg

 

[M Gregg]

The reason I ask is because I want to put a choke in the supply and wondered how much voltage I could lose without damaging the cathode! The other way would be to use 6.3v with higher current plus choke.

Regards
M. Gregg

 

[Joshua_G]

On some tubes datasheets the tolerance for heater voltage is specified. When it isn't specified, I believe +/-5% is the convention.

 

[M Gregg]

Hi,

I am just working on some modules to try the line stages.
(Isolated DC to DC converter to float the heaters on the B+ rail.

Thank's Joshua.

 

[Joshua_G]

There is no need for DC2DC converters in order to float the heaters voltage.
Furthermore, it is beneficial to have the heaters at about 30 Volt above ground.

 

[M Gregg]

I am only using one dc supply to power the line stage (2 x ecc88) + a couple of EM 81's. Its just a fun project. However I am not using Tx windings so the ECC88's heaters have to be isolated form the EM81's.

 

[M Gregg]

Its been quite interesting so far with a B+ regulator with 50ma current limit inverter HT 350VDC. I know that High frequency ripple may be a problem! I just want to see if I can make something useful powered from a wall wart! The heaters start up fine wth a soft start circuit and the HT powers the EM81's which run O.K. So I suppose its time to see what happens with the line stage!

 

[M Gregg]

Hi,

What do you think of High value smoothing caps in the B+ Line? 5000-10000uF with 0.1 and 0.01 bypass caps?
If I Run the HT high and regulate at half supply to get a smooth B+?
I guess someone has already tried this!

 

[analog_sa]

Hi,

What do you think of High value smoothing caps in the B+ Line? 5000-10000uF with 0.1 and 0.01 bypass caps?
If I Run the HT high and regulate at half supply to get a smooth B+?
I guess someone has already tried this!

Audio Research has tried something very similar in the REF series. With dismal, IMO results.

 

[M Gregg]

Audio Research has tried something very similar in the REF series. With dismal, IMO results.

Interesting! So Cap Ind Cap may be a better choice after the regulator?
Can you remember what product in the Ref series?😕

 

[analog_sa]

2820uF in REF3 and almost 4000uF in REF5. I forecast 10,000uF for the REF6 🙂

Towards the end of this page 6moons audio reviews: Vacuum State RTP3D there is a fun comparison table featuring the REF3.

 

[fdegrove]

Hi,

Its been quite interesting so far with a B+ regulator with 50ma current limit inverter HT 350VDC. I know that High frequency ripple may be a problem! I just want to see if I can make something useful powered from a wall wart! The heaters start up fine wth a soft start circuit and the HT powers the EM81's which run O.K. So I suppose its time to see what happens with the line stage!

Get rid of the HF ripple first, then use your best caps as a source of energy.

Cheers, 😉

 

[M Gregg]

Hi,

Just a quick question,

From the Aikido preamp drawing values for the capacitors on the cathode bypass capacitor C3.

What is 1uK/16v? Is this a typo I.E should it be 1uF?

Quote

​

​

C1 0.1 - 1μF* Film or PIO Same Same Same Same
C2 0.1 - 4μF* Film or PIO " " " "
C3 1μK/16V (optional) " " " "
C4 None " " " "
C5 0.01 - 0.1μF (optional) " " " "
C6 0.1 - 1μF* Film or PIO " " " "
C7 47 - 470μF-6.3V - 16V " " " "​

C8 0.1 - 1μF* Film or PIO

Has anyone used Takman metal film resistors? Any thoughts!

Thank's
M. Gregg😕

 

[Allen Wright]

I would take 1uK to mean 1000 uF (k being 1000)

It's not a standard nomenclature though, but fits with a cathode bypass and the low voltage rating.

Regards, Allen

 

[M Gregg]

Thank's Allen.

Looks like a black gate then!

Regards
M. Gregg