the Poor Man 660 support thread

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This is my TC network , modified the attack plug connection so i can leave C4 on the PCB and added a Big quiet fan with speed control ! ( PM670 can be turned on all day  :) )

Man I LOVE my PM670  :-*
 

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tekno808 said:
This is my TC network , modified the attack plug connection so i can leave C4 on the PCB and added a Big quiet fan with speed control ! ( PM670 can be turned on all day  :) )

Man I LOVE my PM670  :-*
Click to expand...

Nice!
 
I had some extra tubes in (thanks radiance!) and so i have some even better matched pairs now and that made a subtle difference. I used 6n5p's and out of 12 tubes i have some really nice matched pairs but i could do with just 8 tubes.
I only decided to just one 5687 in the sidechain anyway because i can't hear any difference and it's just more 'stable' and produces less heat and power. Even still with just 1x 5687 it uses a massive 104 watt!  8)
I also played a bit with the bias to even out left/right a bit more which also helped. I don't think that the -2.4v is an absolute.

The only thing i still want to do is put in better input trafo's, i know it will make quite a big difference. I did use edcors in my d-aoc in the beginning and upgraded to lundahls which made a BIG difference. The edcors just sound a bit muddy to me compared to lundhals.

I really love my PM right now and i'm glad i modified it!
 
dagoose said:
I had some extra tubes in (thanks radiance!) and so i have some even better matched pairs now and that made a subtle difference. I used 6n5p's and out of 12 tubes i have some really nice matched pairs but i could do with just 8 tubes.
I only decided to just one 5687 in the sidechain anyway because i can't hear any difference and it's just more 'stable' and produces less heat and power. Even still with just 1x 5687 it uses a massive 104 watt!  8)
I also played a bit with the bias to even out left/right a bit more which also helped. I don't think that the -2.4v is an absolute.

The only thing i still want to do is put in better input trafo's, i know it will make quite a big difference. I did use edcors in my d-aoc in the beginning and upgraded to lundahls which made a BIG difference. The edcors just sound a bit muddy to me compared to lundhals.

I really love my PM right now and i'm glad i modified it!
Click to expand...

I use a second PT for the heater and placed the 2 heater PSU with heatsink ( temp about 54°C after a few hours ) away from each other and can use the 8 tubes without any problems !
With only one 5687 you have a slower release !
Have in mind that the 6n5p use about 200ma more current, that's 400ma more / heather PSU !

I have and used 6BC8 NOS NIB tubes from ITT ,GE NOS tubes 6BZ8 and 6n5p not matched and they al sounds the same to me " I like the sound :) " , maybe the 6n5p sounds a little different in the high frequencies ( i didn't like it ) .
With the ITT 6BC8 and the 6n5p i also have a little more headroom !

So i use the 6BC8 from ITT and it sounds great !! and my Edcores certainly do not sound muddy ! But i'm curious about your Lundhals mod  ;)

Grtzzz,

Danny.
 
tekno808 said:
I have and used 6BC8 NOS NIB tubes from ITT ,GE NOS tubes 6BZ8 and 6n5p not matched and they al sounds the same to me " I like the sound :) " , maybe the 6n5p sounds a little diferent in the high frequencies ( i didn't like it ) .
With the ITT 6BC8 and the 6n5p i also have a little more headroom !

So i use the 6BC8 from ITT and it sounds great !!
Click to expand...

Did you match your tubes?
 
radiance said:
tekno808 said:
I have and used 6BC8 NOS NIB tubes from ITT ,GE NOS tubes 6BZ8 and 6n5p not matched and they al sounds the same to me " I like the sound :) " , maybe the 6n5p sounds a little different in the high frequencies ( i didn't like it ) .
With the ITT 6BC8 and the 6n5p i also have a little more headroom !

So i use the 6BC8 from ITT and it sounds great !!
Click to expand...

Did you match your tubes?
Click to expand...

No, i don't have the need to match from what i hear and everything work like it should be !
But in a day or 2 i have a Digital tube tester with a curve tracer ( because I'm curious ), then i wil match and let you now if there is a big difference in sound ! But I doubt it .
All tubes i have are brand new  (real NOS) and don't think there wil be a big difference !

Danny.
 
tekno808 said:
No, i don't have the need to match from what i hear and everything work like it should be !
But in a day or 2 i have a Digital tube tester with a curve tracer ( because I'm curious ), then i wil match and let you now if there is a big difference in sound ! But I doubt it .
All tubes i have are brand new  (real NOS) and don't think there wil be a big difference !

Danny.
Click to expand...

You must be extremely lucky and somehow managed to get tubes which are close.
Looking forward to your findings with the digital tube tester.
 
ok lads got my poorman working after a year of problems  :)  now i have a few issues what need sorting out , if anyone could help that would be helpful.

This is a standrard pm no mods

1}why is it when i move the attack to ccw or cw the meter moves with no program material been played ?

2}why is the midrange been push to the front and i get a high loss about 5db


thanks in advance


sklal1
 
skal1 said:
ok lads got my poorman working after a year of problems  :)  now i have a few issues what need sorting out , if anyone could help that would be helpful.

This is a standrard pm no mods

1}why is it when i move the attack to ccw or cw the meter moves with no program material been played ?

2}why is the midrange been push to the front and i get a high loss about 5db


thanks in advance


sklal1
Click to expand...

You've got to give us more info. Did you match tubes? What heater PSU? What toroid? etc. etc.

You might have mentioned all this earlier in the thread but I'm not going to search for it...
 
ok radiance.

no match tubes, how do i do this?

ac heaters


Tx R2-0134-002  Rondo 134VA


ok sorted out the attack movement thing ,it was the ac heater wires interfering with the tubes.



still wondering about the  midrange been push to the front and the  high end loss which is about 5db.

thanks

skal1





 
Hi folks - I did the Avel Lindberg GB about  three years ago for North America .Were there any heating issues observed in the toroids .I am half way through the build.Even at time somebody had tested the Edcors and they were overheating when kept inside the case - I was just reading through Kevin's problems
 
ok lads my psu has gone down agian  :( .


I have replaced all blown parts , now i am getting some strange behavior at q1 all pins are showing 400v is this correct ?, also if i connect up the 1rf840 on 245 rail it burns out r5 475 ohm resistor.

so now i have left out the 1rf840 and the 475 ohm rs is ok , but the volages do not match those of kapser at the collector junction of q1 n q2  and r7 and irf 80s.

My voltages , collector junction of q1 n q2 400vs and at junction of  r7 and irf 80s  51vs
see

http://www.twin-x.com/groupdiy/albums/userpics/PM_PSU_schemo_WReads.jpg


any help would be nice

cheers

skal1
 
Got a box of Russian tubes and just about to start matching. :)

Is it a good idea to load the 245V HT output while its not being used?
I was thinking a 500K.  Have vague recollections of someone saying this many many posts ago.

 

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I used a 500k to load the 245 HT in the end.

I've done Pier's mods to the psu, all good.

Have a quad of matched 6np5's ready to load.  :)

My next question...

So i've added a separate AC heater xform for the mu tubes, this transformer doesn't have a center tap. (which normally goes to ground on most tube circuits) 
Should i add 100 ohm resistors from the xform secondaries to the psu ground?

Or is this only done when different secondaries of the same xform are used for HT and heaters?
thanks
paul

 
heyho,

my poorman is going to be nearly finished! I too had some trouble with the power supply. I blew nearly 10 RF820 and some 840.
I want to report my findings here; maybe it´s helpful to someone.

First thing is that I mixed up the 1:4 and 4:1 transformers. I kept them in my drawer too long and I accidently supposed they are all the same just wired backwards. This blew Q1. After I switched all transformers to their right place my psu was working fine until:

I use a very crappy meter, ripped out of an old tape deck. It zeroes at 0,33V and even with the 5k pot it is very hard to set. So i stripped 200 Ohm in parallel, but then Q1, which was 820 then, blew again. I´ll get some more 840 soon and hope to get my meters working well.

So my question is, if it will affect the sound (mybe gain?) in any way if I reduce the Meter resistor (which is in series of the tubes) to such little value?

My gain is btw. only 13dB not 18db.  How comes?

best greetings,
S.
 
I've lost my copy of the poorman schematic. I've got pretty much all the parts, just a case and a few resistors left to order, but just can't find the schematic anywhere. I'm sure I could build it from all the docs and info in this thread, but would prefer to have them. Anyone know where I can get a new copy from? Obviously happy to pay an "admin"/postage fee.

Any pointers greatly appreciated.

Cheers
 

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