the Poor Man 660 support thread

[[silent:arts]]

[quote author="rrs"]What would be a option for the bypass ?[/quote]
using the Bypass PCBs you need to power them to let Audio pass (this is more a "compressor In" switch). any "on" switch will work.

[quote author="rrs"]Also looks like I need to solder some resistors to these suckers. Is anyone able to help regarding values and working out where the go??[/quote]
look at page one in this thread, there is a link regarding the switches and resistor values.

 

[LeperKing]

Folks,

I've noticed that the vast majority of people are ordering the cases with the cutouts for the smaller SIFAM RETRO AL20SQ. I personally prefer the look of the larger SIFAM AL29WF CLASSIC METERS as they fillout the front panel better, and they'll match the colour of the panel as well.

Is there any technical reasons to pick one meter over the other?

Thanks,
LK.

 

[emrr]

Some more attenuator thoughts. Rowan says he's using 12 position stepped attenuators with no problems, but here's a few more options to coax a groan out of him.

Let's say one had some 600 T's sitting around. Any reason not to use them on the primaries of the GR and SC amps, with some fixed resistances on the secondaries, rather than doing all that dual stepped wiring?

Or, stick with dual stepped atten on the GR amp input secondary as prescribed, but use dual pot on the SC amp. That would do away with the 'ultra-precision balance' factor in the side chain, but not in the audio amp path. Considering the number of limiters that use dual pots in the audio path position, I'm not sure how much difference the average punk rock engineer would notice with them only in the SC amp.

 

[abby normal]

[quote author="LeperKing"]Folks,

I've noticed that the vast majority of people are ordering the cases with the cutouts for the smaller SIFAM RETRO AL20SQ. I personally prefer the look of the larger SIFAM AL29WF CLASSIC METERS as they fillout the front panel better, and they'll match the colour of the panel as well.

Is there any technical reasons to pick one meter over the other?

Thanks,
LK.[/quote]

I posted this in another thread but if you were looking for an original look,

[quote author="abby normal"]I was just checking out my diagram of the original's dimensions,

If we were to go off the exact dimensions of the original's front panel (not the whole rack) height we would need a 5U Par-Metal type rack unit (original height @ 8.375" x 16" without ears, 5U would be 8.73" x 19", but the original panel did not have the rack ears included in those dimensions, the par-metal without ears would be 16.5" so it would be a pretty close fit).[/quote]

 

[rrs]

[quote author="[silent:arts]"]

[quote author="rrs"]Also looks like I need to solder some resistors to these suckers. Is anyone able to help regarding values and working out where the go??[/quote]
look at page one in this thread, there is a link regarding the switches and resistor values.[/quote]

Log Pot to Switch Excell Sheet

Thanks :thumb:

I have the 12 pos 2 deck for threshold and gain Here. So just wondering how to approach that (with the 2 deck) ? Also what wattage do these resistors need to be?

 

[[silent:arts]]

David,
the second deck need the same resistor values as the first deck, ideally matched pairs.
1/4 or 1/2 watt is fine

 

[[silent:arts]]

HEATER PSU

the Heater PSU is a rectified, unregulated one.
the bridge rectifier should be a 12A or more, mounted off board to the chassis. they look like this:

behind the rectifier we have:

we want to be as near as possible to 6.3V, this is done by the value of R15.
again: this resistor is mounted off board and gets very hot. a 50W resistor is a good idea, something like this:

now, what value do we need ?
according to my data sheets:
6BC8 @ 6.3V = 400mA
5687 @ 6.3V = 900mA
this results in 2.6A heater consumption EACH channel.
now you can do the math :green:

one problem we have with the "right" value of R15:
- mains voltage will vary
- the secondary of each transformer will vary
- the consumption of each tube will vary

best thing is to have a few values handy to test it.

 

[Jonkan]

Quick question. Would it be stupid to try and fit a stereo unit inside a 2u case? It a 360mm deep standard case from robeshop.

Of course with some ventilation.

I have limited rackspace over here.

Thanks!
/J

 

[[silent:arts]]

I have limited rackspace too, but a stereo Poor Man in a 2u case is a no no
- if you don't want to put fans inside.

I would go 3u with a 1u ventilation space over it ...

the 5687 get really hot (900mA heater each ...)

 

[Jonkan]

Ok, i guess i have to sacrifice some rackspace then! Thanks!
/J

 

[Moby]

Guys, does stereo unit has "stereo mode" or just dual mono?

 

[Purusha]

I have a question.

Would this be a good cap instead of the 10uF 250V Wima (audio boards)

LINK

And why do we need the optional lytics for? (BOM)[/url]

 

[Emperor-TK]

[quote author="[silent:arts]"]
6BC8 @ 6.3V = 400mA
5687 @ 6.3V = 900mA
this results in 2.6A heater consumption EACH channel.
now you can do the math :green: [/quote]

Damn, now I need to run a new dedicated breaker to my studio just to turn my stereo unit on!

So I should probably drop my idea to do a 8 channel unit in a 2RU chassis? :green:

The Poor Man already has a wikipedia page:

Poor Man

 

[[silent:arts]]

[quote author="Moby"]Guys, does stereo unit has "stereo mode" or just dual mono?[/quote]
you can stereo link them

[quote author="Purusha"]Would this be a good cap instead of the 10uF 250V Wima (audio boards)[/quote]
no, we want the WIMA MKP4

[quote author="Purusha"]And why do we need the optional lytics for?[/quote]
you don't need them, they are - optional

 

[Purusha]

Volker, what kind of rotary switch can we use for 6 step TIME CONSTANT?

Cheap 2x6 Lorlin maybe? :grin:

 

[[silent:arts]]

yes

 

[RedNoise]

Hi there....
could someone tell me if sifam s25 could suite the poorman??Volker??Analg???
thx for help , I need this info to tell Tat Purusha S25 dimensions to cutout my case...
thx.
Edit: S25 is 1mA

 

[[silent:arts]]

[quote author="RedNoise"]Hi there....
could someone tell me if sifam s25 could suite the poorman??Volker??Analg???
thx for help , I need this info to tell Tat Purusha S25 dimensions to cutout my case...
thx.
Edit: S25 is 1mA[/quote]
sorry, I can't test everything in front.
the specs are VU, which does work.
if you use anything else it is on your own risk.
thanks

 

[RedNoise]

thx for answer Volker , I understand you're busy...
As I'm noob I just asked if someone could gave me his advice...
btw , thx.

 

[kafka]

Quick question - do the 5687's appear in the signal amp, or are they solely in the sidechain amp?

...


[ok, thinking about the sidechain out loud here] ...

OK, and I think I understand the original FC660 design a bit better, and applying to the parts list ... So, the first pair of 5687's operate in class B, with the cutoff point determining the threshold. Therefore, the sidechain amp has to be balanced (`cause you can't make a SE class B amp (duh!)). You've got another stage of voltage makeup, which just stays balanced `cause it's just easier to stick another dual triode in for each side, and you've got to run it through another xfmr before the rectifier. ... and the time constant is just determined by an RC filter.

Eh. Seems like a lot of work and iron to me, for something that doesn't actually pass the signal. Gotta be some way to do it with an FPGA. :wink: