Changes for Dowdy chokes in 45 Stereomour

[Alonzo]

I'm getting parts and things ready for my upcoming Stereomour build.  I'm planning on going with the 45 setup for this one and Dowdy chokes.  Are there any other changes other than increasing the output capacitor value that I need to consider?  I'm also not using the selector switch or volume pot so the Dowdy's will sit on the very front of the top plate.
Thanks,
Alonzo

 

[Alonzo]

Another twist to the build, I'm scrapping my current 45 amp for parts so this Stereomour will get EXO-145 Nickel outputs and some vintage Ni grid chokes.  Probably will go for CLC instead of CRC with C7x chokes in the power circuit.  Are there any "gotchas" that I should plan for before I start the build?
Thanks,
Alonzo

 

[2wo]

With all of thought's good bits, it would be a shame to not go fully shunt regulated.

BH had a semi kit a few years ago, I bought one and never looked back.  I am working on a version that uses the Salas Reg. Progress is slow though...John 

 

[Alonzo]

I have to confess that I don't fully understand shunt regulators, I bought the initial SR45 kit but it's still in a box because I haven't sat down and gone over what it does.  What would it do for me?  I'm going to have a well filtered power supply, would a shunted power supply be much better?

 

[Paul Birkeland]

A shunt regulated high voltage supply on a class A amplifier is like having the combination of an ideal power transformer, choke, and capacitors (conceptually).

It takes some additional voltage and current beyond what the circuit it regulates requires. 

-PB

 

[mcandmar]

I used a shunt regulator in one of my recent builds, i wanted the Salas SSHV but couldn't get my hands on any PCB's so i found a variation of it made by K&K audio. The BH implementation with a tube intrigues me, but i have no idea how it works, or its benefit vs solid state.

Pros, think of it like active noise cancellation for your B+ supply.

Cons, they need a decent sized voltage overhead of ~50v, they usually double the current demands of your raw B+ supply, and they produce a lot of heat.  There is also max current and voltage limitations that may not be suitable for your application.

I'm a convert as i think they are brilliant

 

[Alonzo]

Got my Stereomour in yesterday and got her painted.  Rough layout pic attached, starting assembly tonight.

 

[johnsonad]

Wow!!

 

[Alonzo]

Assembly done, resistance checks were good.  Voltage checks were off at C1, C4, 11 and 20 (26, 25, 31, 20 VDC).  All about half there expected values.  I swapped 45's and the low values followed the tube.  Replaced and sound checked but no (very little) sound, I have to turn the Smash all the way up and I can here low music from both speakers from a couple of inches away.  I must have messed something up with either the input 100K resistors or with the output transformer hook up. 
Gonna take a pie break and check it later.  Here's some pics of the build.

 

[Alonzo]

One step closer, remembered that I'm not using the OT-2 so I lifted the ground wire to the speaker black post and got good music from the right channel, not so much from the left.  The speaker terminals measure 6.8 ohms for the left and 0 for the right so I'm going to check all the connections back to the output transformer and see what's up.

 

[Alonzo]

A new BH amp is alive and kicking.  Playing Gary Clark Jr. Blak an Blu as a debut album.  I had to go back to the OT-2's cause of some strange readings on the C side with the EXO145's.  Also had a problem with shorting B6,7,8.  But that's all fixed now and the magic is playing (softly cause its 1130 but wait till tomorrow ).
Still to do;  3.3 Muldorf Supremes in place of the 4.7's.  Get the EXO-145's figured out and put back in.
My kits for this year are ticking off pretty good, got a SmashQuiet and a Mainline then a Stereomour II left and I'm done...