the Poor Man 660 support thread

[radiance]

Stupid question , but whwre I can buy the pcb for this project ?
thanks

You can't...

 

[idylldon]

Lolo-m,

I tried to send this via PM but your inbox in full.

I built a tube-matching setup based on your schematic to test some Russian tubes I just got for my PM670.  Although it seems to work, adjusting the VU meter using the multi-turn pot in parallel with it is difficult because the slightest movement of the pot swings the meter wildly.  I've tried various values for the pot, but they all exhibit the same problem.  I can't really dial in 0 VU because it's impossible to get that fine of an adjustment with the pot; it either swings high or low and even putting a screwdriver on the pot's adjustment screw makes the needle move.  Is there something I'm missing here?

Thanks for your time,
--
Don

 

[Rob Flinn]

can you put the pot in series with a resistor either side to reduce the range ?

 

[tekno808]

Almost finished my PM670 , tested 1 ch ,working and i like what i hear

In the PM660 wiring guide there is a connection to stereo link switch , where is the other side of the switch connected to ? ( i suppose to the second PM660 but not shure )

thx...

Danny.

 

[tekno808]

I did the PSU mod and gonna use a second PT for the heater .

 

[radiance]

That looks GOOD!

 

[[silent:arts]]

Wow, I LOVE nice and clear builds - congratulations!
(your personal banner will be added later, I'm in a rush)

In the PM660 wiring guide there is a connection to stereo link switch , where is the other side of the switch connected to ? ( i suppose to the second PM660 but not shure )

yes, same position at the second channel it is
(with the switch in the middle of the wire)

 

[idylldon]

can you put the pot in series with a resistor either side to reduce the range ?

Thanks.  I'll give that a try.

Cheers,
--
Don

 

[[silent:arts]]

 

[tekno808]

Thx for the banner !

PM670 Finished , working great and sounds great !! no tc network mod or SCamp booster .
Just mastered one of my songs with it and i'm verry happy with the sound !

Here a few other pictures.

 

[tekno808]

And another pic with PM670, MixBuzz, Gssl and Sontec M250EP !

A comment that I want to do, when you use the original heater psu the minus of the 6.3v is connected to the ground !

So when you use the slow start heater psu, its not connected !, i connected the minus of the 6.3v to the ground and it reduced hum and noise !!!

I looked at several pictures of finished PM670 that used the slow start heater and nobody did this ???


Thx to all for making this possible !

 

[radiance]

I looked at several pictures of finished PM670 that used the slow start heater and nobody did this ???

Look again...the slow start heater PSU board has a ground terminal which should be connected to your (star) ground.
The minus is connected to ground on the PCB ....

Also, are these solid aluminium heat sinks you're using? Do they get hot after running the unit for a while with the lid on?

 

[tekno808]

Look again...the slow start heater PSU board has a ground terminal which should be connected to your (star) ground.
The minus is connected to ground on the PCB ....

Also, are these solid aluminium heat sinks you're using? Do they get hot after running the unit for a while with the lid on?

Ok not everyone but i saw a few with the slow start heater PSU not connected to the ground.

Temperature on one heatsink heater PSU is 57°C and the other 60°C after a few hours ! ( i use a vented cover from modushop! )

Danny.

 

[idylldon]

Thanks to Rob's suggestion, I got my testing rig working.  I tested 16 NOS 6BC8 and have to say that there were 4 of them that had matching halves and lined up enough to call them a quad.

I then tested 16 NOS Russian 6N5P and the results were much, much better.  There were a dozen with closely matched halves and I could easily match those to make 3 matched quads.

I'm going to give it a try with the 6N5P tubes to see how the unit behaves with closely matched tubes.  I also want to check the heater current to make sure I don't stress out that circuit too much since the Russian tubes draw more heater current than the 6BC8s, .55A - .65A vs. .4A, respectively.

I was kind of disappointed to see how widely ranging the NOS American tubes were. 

Cheers,
--
Don

 

[tekno808]

Thanks to Rob's suggestion, I got my testing rig working.  I tested 16 NOS 6BC8 and have to say that there were 4 of them that had matching halves and lined up enough to call them a quad.

I then tested 16 NOS Russian 6N5P and the results were much, much better.  There were a dozen with closely matched halves and I could easily match those to make 3 matched quads.

I'm going to give it a try with the 6N5P tubes to see how the unit behaves with closely matched tubes.  I also want to check the heater current to make sure I don't stress out that circuit too much since the Russian tubes draw more heater current than the 6BC8s, .55A - .65A vs. .4A, respectively.

I was kind of disappointed to see how widely ranging the NOS American tubes were. 

Cheers,
--
Don

I did try the 6N5P , they compress much more compared to the 6BZ8/6BC8 at the same treshold level ( I think , if i remember at 0 treshold also compression ), i think you have to adjust the kathode voltage RV3 !
Soundwise didn't hear much difference !

Don't know where to find a reference for the kathode voltage of the 6N5P, maybe Silent Arts or Analag???

Danny.

 

[dagoose]

I decided to start working on my PM again since right now it's just used as rackfilling which is a shame.
I already ordered a batch of 6n5p (going to match them), an extra trafo for the heater and things like that and i dug up the 5687 tubes that i pulled out from the sidechain some time ago.
But i found something strange with one of the 5687 tubes. When i pulled out the 2 tubes from the sidechain i already noticed that one of the tubes was having some kind of white residue but i didn't really pay attention untill today. I also noticed that one of the tubes has a small crack in the glass in the bottom and also the metalic deposit on top for the getter is also gone.

I know it's broken (no vacuum i guess) but could that be because of the heat of the 5687's? they are running REALLY hot as we all know. Did someone else have the same problem? i have Philips 5687's. Might be something to pay attention at. 

I think i will get 4 new 5687's anyway.. so what is a good and cheap source right now?

 

[radiance]

I think i will get 4 new 5687's anyway.. so what is a good and cheap source right now?

pm me....

 

[dagoose]

I think i will get 4 new 5687's anyway.. so what is a good and cheap source right now?

pm me....

Check you mailbox.  ;D

This is what the tube looks like. (Philips JAN 5687WB 8713)

 

[[silent:arts]]

I know it's broken (no vacuum i guess) but could that be because of the heat of the 5687's? they are running REALLY hot as we all know.

broken and no vacuum is right.
but not because of heat.
from what I can see it is "mechanically" damaged at the socket.

 

[dagoose]

I know it's broken (no vacuum i guess) but could that be because of the heat of the 5687's? they are running REALLY hot as we all know.

broken and no vacuum is right.
but not because of heat.
from what I can see it is "mechanically" damaged at the socket.

I was also thinking about the mechanical stress that broke it but it was already this way before i pulled it out so i guess it must have cracked bbut was before but it was still working. The thing is, i remember it was still bloody hot when i pulled it out or could it still be heating even though the vacuum is gone?
Anyway.. it's broken.