the Poor Man 660 support thread

[Kingston]

I'm not touching the sidechain amp or transformers. the slight distortion they produce can be only a good thing for time constants.

 

[[silent:arts]]

A number of people commented in this thread that the PM670 sound somewhat lacked and they wouldn't use it on master bus. Also a number of people said that Edcor transformers produce distortion and harsh highs or something...
So, how come nobody tried it with better transformers? I'm sure there have to be people with piles of Lundahls?

[quote author=ChuckD]Wow it sounds good, Very much mastering quality[/quote]
build with UTC transformers

 

[radiance]

Input stage uses UTC A15  to Edcors
SC input is UTC A15  to Edcors.

Are you sure it's a A15? Can't find any data on it....

 

[TheGuitarist]

Can i just ask what transformers got replaced? like T1/2/3/4? Just a bit confused with that. Correct me if i'm wrong but it seems like T1 and T3 were replaced yeah?


Or does anyone have suggestions for all of the transformers?

 

[radiance]

Can i just ask what transformers got replaced? like T1/2/3/4? Just a bit confused with that. Correct me if i'm wrong but it seems like T1 and T3 were replaced yeah?


Or does anyone have suggestions for all of the transformers?

Chuck did T1 & T3 AFAIK....

EDIT: wait..now I'm confused. I see 6 edcors and 4 UTC's in there. I know he had a MS en/de-coder thing going but what tranny does exactly what?

ChuckD , we need you to chime in here...

 

[lewilson]

Yes, I wonder what voltage the sidechain puts out with the booster? Completely stock it is around -13 volts.  My 660 clone can put out about 5 times this. and the 6k4p sounds great.
  Im not sure the 6k4p will be the best tube for a stock pm

 

[emrr]

I'm remembering Chuck used the UTC's and the Edcors.  UTC's for mid/side encode/decode. 

 

[lolo-m]

Yes, I wonder what voltage the sidechain puts out with the booster? Completely stock it is around -13 volts.  My 660 clone can put out about 5 times this. and the 6k4p sounds great.
   Im not sure the 6k4p will be the best tube for a stock pm

As the booster is fed with +17/-17, it can't go under -17V even with moding it and adding gain. The idea was only to add some current to charge the cap of the TC network, not to change the voltage swing.
6BA6, 6BZ6, 6K4P will work in the circuit (with or without booster) but with a really little max compression. Expect a few dB (I didn't test but I bet less than 6dB with 6BA6 fed with 136V PSU and less with 250V PSU...).

 

[TheGuitarist]

Hey would there be any problem using any other 600:10k/ 10k:600 transformer? Is there anything particularly special about the edcors? Thinking of buying some sowters or just anything that would be an upgrade really. Sowter have fairchild transformers, expensive but hey. Any other suggestions welcome. Carhnill maybe?

I just can't seem find any info on why (other than cost) the edcors were used.

 

[lolo-m]

Hey would there be any problem using any other 600:10k/ 10k:600 transformer? Is there anything particularly special about the edcors? Thinking of buying some sowters or just anything that would be an upgrade really. Sowter have fairchild transformers, expensive but hey. Any other suggestions welcome. Carhnill maybe?

I just can't seem find any info on why (other than cost) the edcors were used.

The 10K:600 must be designed for push/pull. 600/10K can be anything, but you have to check if no oscillation appears.
EDCOR trannies are not bad at all when stock wired properly  ;D.
Most of the people thinking the PM sound not that great are forgotting several things:
- Match your tubes as close as possible before saying anything about sound.
- if 6BC8 was a really great varimu tube, I bet somebody would have made a great comp with it 30 years ago...
- EDCORs are cheap. Build a complete working unit, then follow my first 2 points... If the sound isn't good enough, try some other tubes and/or transfo.

I'm happy with my 6BC8 and EDCORs. But I never planned to use it as a mastering comp... Its little distortion figure can be a nice feature even in mastering work. If you don't want distortion, buy a CRANE SONG  ;D...

 

[radiance]

The 10K:600 must be designed for push/pull.

Forgive me my ignorance...what is push/pull? And in what way are push/pull transformers wound differently?

 

[lolo-m]

The 10K:600 must be designed for push/pull.

Forgive me my ignorance...what is push/pull? And in what way are push/pull transformers wound differently?

I'm not expert in transfo too  ;D but here is what I know:
The Fairchild topology is entirely push-pull. That means that the plates current is entirely fed through the transformer.
PSU is connected to the center tad of the transformer primary and the polarisation current is always running into/trough the transformer. This means that the transformer must be able to handle the heat due to that current into its windings resistance. This means too that there's a magnetic polarisation into the transformer and is the core is magneticaly saturated by polarisation current you'll have distortion when you add audio current. I'm not really sure about this last point, so if I'm wrong please correct me .
The EDCOR handle both easily due to his 2,5W rating...

 

[jackies]

I guess he refers to the center tap being used in 10k:600 and not being used in 600:10k (I don't have the schematic handy to confirm).

As the booster is fed with +17/-17, it can't go under -17V...

I guess we need to come up with further boost then? How about high-voltage SCAB for 6k4p?

 

[lolo-m]

I guess he refers to the center tap being used in 10k:600 and not being used in 600:10k (I don't have the schematic handy to confirm).

As the booster is fed with +17/-17, it can't go under -17V...

I guess we need to come up with further boost then? How about high-voltage SCAB for 6k4p?

Something is on its way... but not for the PM...

 

[radiance]

The 10K:600 must be designed for push/pull.

Forgive me my ignorance...what is push/pull? And in what way are push/pull transformers wound differently?

I'm not expert in transfo too  ;D but here is what I know:
The Fairchild topology is entirely push-pull. That means that the plates current is entirely fed through the transformer.
PSU is connected to the center tad of the transformer primary and the polarisation current is always running into/trough the transformer. This means that the transformer must be able to handle the heat due to that current into its windings resistance. This means too that there's a magnetic polarisation into the transformer and is the core is magneticaly saturated by polarisation current you'll have distortion when you add audio current. I'm not really sure about this last point, so if I'm wrong please correct me .
The EDCOR handle both easily due to his 2,5W rating...

Ah, I get it. I was confused causeI thought you where talking about the 600:10K tranny from which the center tap is not used....

 

[elektrovolt]

- if 6BC8 was a really great varimu tube, I bet somebody would have made a great comp with it 30 years ago...

take a look at the Universal Audio 175b

I just tested one working channel in my poorman, but I really find it dull sounding and with a slow attack and release. it could be that I just have monday morning edcors...
my 6bc8's are matched.

 

[Moby]

take a look at the Universal Audio 175b

Great comp but 10 times cheaper than FC670 . Yes, it could be PM 670 

 

[lewilson]

Maybe get rid of  the first  5687 and put a drive stage in that socket. Install some coupling caps .Then have edcor make an appropriate output trans for that setup.
Personally I like my slow stock  unit. Ive been  using it  alot.

 

[elektrovolt]

lewilson, what do you use it on?
actually I do not have a good purpose for a slow compressor like this, I really thought it would be much faster.

this build has been a terrible pain in the ass for me, however it is working now but only not finished.
Due to my financial situation, I think I have to sell my poorman project.
there is just too much stuff around here, and this project was more like a 'poormaker' to me.

I might going to regret this, but we'll see.
if someone is interested in my poorman project (case, edcors, toroid, elma's, stereo pm's and psu, bypass boards, heater boards, meters and SCAB)
PM please. I will put an ad in blackmarket.

 

[Kingston]

Having finished my initial build and having done lots of testing and setting up, this is turning into a huge disappointment to me as well. It's just a VERY expensive distortion box. bad sounding distortion at that.

Instead of months and months of more tweaking and investing in expensive new transformers I'm probably going to start a p2p vari-mu build from scratch.

Another finished poorman going to blackmarket here as well.