the Poor Man 660 support thread

[inputoutput]

Following up on my previous post a few days ago. As mentioned, the voltages dropped fast when one or several tubes were inserted.  So now, finally got my voltages right, also with tubes.  i've been looking for shorts on the audio-pcbs for weeks, but it must have been something with the voltage-regulators.  I changed them from two IRF840A into two IRF840B !  Looking at the voltage-regulators spec-sheets, I don't see why this should make much difference, but it does certainly work now. Another option might be that I had too much thermal compound, and that the heat didn't transfer fast enough.  Anyway, it could also be the 840B that made the difference. So all you guys struggling with voltage-drops. Take a look at the those regulators again.

I am glad I bought a big chassis, cause placing of the Edcors play a important part in lovering hum and noise.  So I'll move those around, and post a report as soon as I'm happy with the result.

------------

small question : I've got 0.8 VAC in my heaters.  Does  a little AC in heaters matter in tube equipment?

 

[Moby]

small question : I've got 0.8 VAC in my heaters.  Does  a little AC in heaters matter in tube equipment?

How did you measured 0.8V AC?

 

[inputoutput]

hey Moby! ,

Measured AC between the ground and + on the Heater PSU output. Can also be seen with my scope.  Do you think I Should put a cap in-between?

 

[Moby]

OK, if you measured by scope that's accurate  ;D Well, filament can be done AC, most vintage equipment was done that way but since we have cheap diode bridge  and capacitors today it's piece of cake to make it DC. If you don't have any hum leave it as it is but if the 50 or 60 hum is present than consider some more capacitance smoothing on the board (near tubes).

 

[lolo-m]

small question : I've got 0.8 VAC in my heaters.

It's a result of the high current eated by the heaters... The AC you see is what caps can't absorb...

Does  a little AC in heaters matter in tube equipment?

We're in push-pull technology here, so you shouldn't ear any hum caused by heaters... Original Fairchild's heaters are fed by pure AC... So I bet we won't have any problem with this little AC !!!
Anyway, if you use NOS tubes, let the heaters burn during about 48 hours... After that, the heaters will heat less current and this AC should be lower...

 

[inputoutput]

ok, thanks Lolo-m! 

Tested different caps, but it didn't seem very effective on the AC voltage anyway.

 

[inputoutput]

Think I'm almost done with mine now. Will use it in the studio for a week or two to get to know it before I wrap it up. Specs are pretty decent.  Placement of trafos, metal-covers and wiring is important to get the noisefloor down.

It is easy to make vintage-looking meters. Just buy a new one, and stuff it in an old case.  A little pictorial :

two new buddies

BIG thanks to Analag / [silent:arts]

 

[radiance]

Love your design.

..are those cases from modushop btw?

 

[inputoutput]

yes they are

 

[Holger]

@Inputoutput, cool meter idea. Maybe we should start a new thread: meter modding

 

[ultra-alex]

impressive! holy ****...

 

[[silent:arts]]

very cool looking unit 8) 8) 8)
and good to hear you sorted the PSU problem out
for now I would vote for the best looking PoorMan right now.
but be careful, others might follow ;D

 

[crisotop]

wow!  Very nice looking unit indeed!

 

[lewilson]

Id like to thank  Analog and silent arts for a great project.Im enjoying my compressor.Thanks

 

[ChuckD]

Wow very cool looking units! Love your design! very tough.




Hey Tommy and giltmastering count me in on the Transformer for this unit.
I need one as well. I too am lagging on this project but now want to get it finished.

-Chuck

 

[lolo-m]

ChuckD, Tommy and giltmastering, I think it's time to make a Black Market thread...
This thread is pretty long as is , isn't it ?
Put PM 660 and PM 670 and transfo in the name, I think you'll have every interrested people...
And post a link on this thread  .

 

[idylldon]

Thanks again to silent:arts and analag for such an amazing project.  For a variety of reasons I didn't need/want a rack case for this one, so I used an old PA head cabinet that I've had lying around for quite a while.  The VU meters are some old Hoyts, and that little aluminum band between them hides the meter lights, which work on 12 volts.

The VU meter zero adjustment pots are accessible using a small screwdriver through the top louver just to the side of the relevant meter.



The bottom:



One final one with the lid off:



There were no surprises when I fired it up, and it only took a few minutes to adjust all the voltages.  The high-voltage supplies are pretty much right on.  Once I dial in the 6.3 supply I'll purchase the correct value resistor and get rid of the adjustable one.  

Cheers,
--
Don

 

[inputoutput]

cooool... very nice looking! great work man

since my last post, I turned some of the edcores a 45 degrees angle from each-other.  Plus, added some more metal-walls in between. The noisefloor dropped an additional 4dB. I´m down with a almost not notable hum at -82dBu. Which I can live with. 

The Heater-psu-boards  picks up a lot of noise from the toroid, so if you use those, place the heater-psu's as far away from the power-toroid and power-wires as possible.  Shove as much metal as possible in-between.  You should also test not using the heater-psu boards if you are experimenting with lowering the hum.

The soundsamples previously posted in this thread do not do this unit justice.  I´m blown away by how good the Poorman is.  Analag has done a fantastic job. Looking forward to the next projects coming from your hand Analag! can´t wait.

 

[[silent:arts]]

WOW
they are getting more and more creative, I love it ;D ;D ;D
cool build, congratulations.

 

[lolo-m]

WOW
they are getting more and more creative, I love it ;D ;D ;D
cool build, congratulations.

I definitively agree with you !!!
Nice work, I wish I could be so creative but I'm not :'(...