the Poor Man 660 support thread

Advertise with us
Shop deals on ebay
shop deals on amazon
GroupDIY Audio Forum

Help Support GroupDIY Audio Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
I was planing to do a "DAOC like" filaments PSU but the slow turn on is a great idea, maybe totaly useless (DAOC works without it) but a great idea !!!
Click to expand...
Filament Current consumption for DAOC is half from PM660. Yes it works without regulation but ... I don't wanna to repeat same thing hundred times  ;) PM works too with just a resistor. It's your choice I just suggest safer and as most people claim better (more stable)sounding solution.
 
to keep this simple:

I'm with emrr.

a regulated PSU won't hurt, but I disagree it is a better sounding or whatever solution.
however it is the best solution if you don't want to find out your value of your "mystic" R.

won't finish it today, but I will do a PCB design with Moby's LM338 slow start suggestion.
that is all I can offer for this topic.

(the analag original way is working)
 
Moby said:
Filament Current consumption for DAOC is half from PM660.
Click to expand...
You certainly wanted to say : Filament Current consumption for DAOC is half from PM670  ;D
DAOC current is 6 x 300mA = 1,8 A
PM660 is 2 x 400mA + 2 x 900mA = 2,6A
LM350 handle 3A current out...
LM338 handle 5A current out... Anyway you're out of it's power with only 1 LM338 PSU for a PM670

In both cases, you've got to use 2 filament PSU for a PM670.
 
Moby said:
My mains voltage fluctuates about 112 to 128; I think not so stable.
Click to expand...
Cool, than you will have a filament voltage swing of +/- 0.8V... If it's OK with you to supply from 5.5-7.1V
Click to expand...

So shoot for 5V at the bottom if you really want to be sure 6.6 is the top.   Works fine with most tubes. 

lolo-m said:
I disagree, 7 tubes getting old fast for one filament fail is a real risk...
Click to expand...

Not sure I am following this one.  If one filament fails our ears should surely tell us that a tube needs to be replaced.  Not likely at all that the other 7 tubes would be damaged by a brief period of higher filament voltage due to load lightening on the supply. 

Can you find brand new 6BC8 or 5687 ? No, the best you'll find will be NOS.
Are NOS tubes secure : no. There's minor risks of glass porosity, real risks of bad treatments (by shipping or ex-owner).
If your tube fails, the problem is 100% yours. I prefer to repair sometimes my PSU with brand new IC's than to change my "not-nowadays-built" tubes.
Click to expand...

Ah, but how many times in repair world have we found 15-30 year old parts that could not be easily replaced; either because they aren't made or the current parts no longer fit on the board in question, and required a circuit board hack.   I spend way more labor time fixing new stuff than I do 70 year old stuff.  Tube stuff is never this way, and these tubes are CHEAP.  I find no excuse for not buying 3 times as many as one might need in the expected life of the piece.   A $900 PM670 build with 2 additional tube sets adds under $50 (USA at least) to the price.   Tube hoarding is part of the bargain with owning tube gear.  You face this sooner or later and sooner is smarter than later.  In my experience I expect all other possible failures from a tube OTHER than filament to occur first.  Either way it's a tube replacement.  They decide to change the footprints of a several parts on your additional circuit board 10 years down the road, suddenly you find you need a whole new module sometimes.   Just seems an unnecessary additional bet to take for no strong reason, IMO.    I like the 'keep it simple, stupid' plan.   


Moby said:
that is all I can offer for this topic
Click to expand...
Me too  ;)
Click to expand...

me too!  tried to stay out of this before already. 
 
Just to end my part of this topic, and not to hurt anybody these are just points of view:

emrr said:
If one filament fails our ears should surely tell us that a tube needs to be replaced.  Not likely at all that the other 7 tubes would be damaged by a brief period of higher filament voltage due to load lightening on the supply.
Click to expand...
If you can hear a 5687 fail in dual operation mode, I just think we don't have the same hears... because I'm sure I can't hear something out of the signal path  :-\ :-\ :-\

emrr said:
Moby said:
that is all I can offer for this topic
Click to expand...
Me too  ;)
Click to expand...
me too!  tried to stay out of this before already. 
Click to expand...
I'm definitively out of this now.  ;)
 
lolo-m said:
If you can hear a 5687 fail in dual operation mode, I just think we don't have the same hears... because I'm sure I can't hear something out of the signal path  :-\ :-\ :-\
Click to expand...

Compression characteristic would surely change; we should hear that part.
 
Whew... got her completed. Recycled case, home-made front panel. Sounds really good. One question, I noticed that the threshold controls seem to be slightly interactive with other. For instance when I adjust the right channel it will affect the left channel meter just for a second and vice versa. Can't hear anything noticeable just curious if this is normal.
fairchild1.jpg



 
Anyone have any sound samples of this unit? I'm still stashing away parts when I can (read: have cash) - would be nice to hear something that'll be in my possession once I do eventually get it put together.


EDIT: ah - here they are:

Before:
http://groupdiy.silentarts.net/pm660/PM660-1.wav
After:
http://groupdiy.silentarts.net/pm660/PM660-02.wav
Click to expand...
 

Latest posts

Back
Top