[regal]

[size=10pt]  I made a sketch of the prefiltering power supply chassis,  I had the two transformers so made it a completely split supply at the time I started it was thought that the Salas reg would be best to have a separate reg for each channel,  way overkill and time consuming. This way I have flexibility  to try some output tubes like 45's or the PX4's with this,  inside the amp chassis at each regulator there is an additional RC (3k &5 uf can) right at the regulators as I had to drop the voltage a lot before the regs.  Hammond seems to have a lack of high current but lower voltage power transformers.  Ideally one wouldn't want to use such a large resistor in the prefilter but it simulates to around 1mV input ripple.   Cool thing about the Reg is even with this heavy filtering the final B+ output impedance will be well under 1 ohm.[/size]
 
[size=10pt][/size]

 

[adamus]

regal,
 
sorry i am not sure you what you mean (missing a few commas, or could be my lack of lit skills!) - are you saying two regs is overkill but you are stilll going ahead with it?
 
should be a superb amp.

 

[nikongod]

NOTE! there is a pretty good chance I misread the schematic... ignore this. maybe not, but probably.
 
5ar4 tie the cathode to the heater because they want to be cool like a directly heated rectifier. I think they were designed to be drop-in replacements for 5u4g, which is direclty heated, and thus inherently cooler
 
They will need separate heater supplies or the 2 B+ supplies are in parallel before any resistors/chokes.
 
I do like the idea of putting a choke input supply before an active filter (overkill FTW!) but 1 5ar4/5u4g can no doubt supply enough current for the whole amp. Separate active regulators for each channel will get you crazy levels of channel separation.
 
If you want 2 tubes in the PS look into damper diodes or half wave rectifier tubes. Very few people use them in commercial products: they are very wallet friendly.

 

[regal]

Its two separate power transformers,   the 5V DH  transformer for the 5AR4's has two secondaries so the two rectifiers aren't sharing their direct heat supply.  The 5V is tied tacross the cathode,  remember the rectified output comes from there to.
 
Yes its overkill,  but Salas recommended basically quadruple power handling for the B+ transformers and I had these transformers anyway.  At the time Salas was pretty adament about using a separate reg per channel.
 
Anyway it gives me flexibility should I want to try different  outputs.

 

[regal]

Here is a shot of the overkill PS prefilter stage on the dirty shop floor with the umbilical cord that came out pretty nice for a decent price.  I got lucky and found a reasonable HV connector at digikey.   The two power transformers are the Hammond 300 series. The tube sockets are for JJ 5AR4 (again overkill much cheaper options than these.) The amp section is almost complete but I had paint complications due to the cold weather, it kept bubbling up,  going to try truck bed liner that stuff looks great and is very durable.  Being my first two chassis build with the added complication of completely separate PS my concern is hum.   I will probably have to experiement with the grounding scheme.
 

 

[adamus]

looks good so far.
 
Hum.. i am playing with parafeed in a single box a the moment. if you can get the OPT about 10 inchs from the power tx, then hum isnt a problem. 
 
I am even running d3a and c3g's on AC and they dont hum at all.
 
 

 

[regal]

Quote:

looks good so far.
 
Hum.. i am playing with parafeed in a single box a the moment. if you can get the OPT about 10 inchs from the power tx, then hum isnt a problem. 
 
I am even running d3a and c3g's on AC and they dont hum at all.
 
 

I imagine that depends on the headphones,  my Grados pick up the slightest hum.
 

 

[adamus]

tested with graods and some super sensitive iem.
 
it actually seems more to depend on the transformers in questio, the edcors were fine but the electraprints (which sound much better) wanted more distance. 

 

[regal]

Quote:

tested with graods and some super sensitive iem.
 
it actually seems more to depend on the transformers in questio, the edcors were fine but the electraprints (which sound much better) wanted more distance. 

Thats great,  I swear a two chassis build makes the build time 4 times as long,  just getting over a bad case of bronchitis hope to have this thing wrapped up soon.  I ordered a pair of ebay WE 417A's at the height of my codeine delerium,  my confidence in them being good tubes is about 10%

 

[adamus]

indeed... just doing a proper job on the umbilical took me a good hour for my two chassis build. The extra cost is also pretty frightening! the cord cost me well over £20, the connectors are not easy to source cheaply.

 

[regal]

Quote:

indeed... just doing a proper job on the umbilical took me a good hour for my two chassis build. The extra cost is also pretty frightening! the cord cost me well over £20, the connectors are not easy to source cheaply.

These connectors are available from digikey and very reasonable I think I paid $15 for the set.  Quality seems good.  I think they are a newer offering as I didn't see them till recently   Made in the UK may be able to find them there:
 
http://www.jae.co.uk/catalogue/new_cat_2005/input_output/SRCN.pdf