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-   -   Cons for using instrumentation tube PS for project amp... (http://www.diyaudio.com/forums/tubes-valves/78795-cons-using-instrumentation-tube-ps-project-amp.html)

2004ex 2nd May 2006 05:02 PM

Cons for using instrumentation tube PS for project amp...
 
I have an old Fluke 407 tube regulated power supply (picked up from a fleamarket with very low cost). Contemplating to build a full amp on top of that by expanding the chassis etc., or using it as a dedicated, permanent part of an amp (like the old Williamson with separated PS and amp chassis).The advantage is obvious - no need to build another elaborate PS and redirect the effort and resources to the amp section. It is regulated (claimed to be <0.5% from 0-555V 300mA) +B and grid bias, and turn-key operation as well. What are the cons for such an approach, besides the awkward physical size and the appearance? I recall someone saying that the 0A3/0D3 tubes could be very bad for amps. Any input will be appreciated, before hunting for a hack-saw from the garage.
Thanks.

DigitalJunkie 2nd May 2006 05:05 PM

Eek..Hacksaw? :(

2004ex 2nd May 2006 05:26 PM

Quote:

Originally posted by DigitalJunkie
Eek..Hacksaw? :(
Thanks for catching that.

DigitalJunkie 2nd May 2006 05:58 PM

I mean,Why cut it up?
Any particular reason?

2004ex 2nd May 2006 08:47 PM

Quote:

Originally posted by DigitalJunkie
I mean,Why cut it up?
Any particular reason?

What I meant was to start modifying the chassis in order to add the amp section - such as by adding sub-chassis, external extentions etc.
No, I won't cut it up. It is a very nice unit.

tubelab.com 2nd May 2006 08:53 PM

I use lab power supplies for designing tube amplifiers. I get the amp sounding right with a lab supply, then design a power supply that hopefully sounds as good as the lab supply. I currently have 3 lab supplies. A Knight, a PACO, and a Fluke 407D. The Fluke is by far the best of the bunch. Enough juice to melt most tubes.

I have seen good working units go for $200 or more on Ebay. I also bought mine on Ebay for $25. It was listed as surplus, untested. It worked fine. If your unit works good, and looks reasonable, you may be able to sell it for enough to build a good power supply. In fact I have built good amps for $200.

Tom Bavis 2nd May 2006 11:47 PM

I agree... it's worth much more whole! I bought a 407 at a hamfest for $15, replaced the leaky bumblebee caps and sold it for $175. Actually, after I replaced the caps and readjusted zero volts, it was within a volt at the top and bottom of every range... a FINE piece of electronics.

Design your amp using it, then sell it or use it for the NEXT amp design...

2004ex 3rd May 2006 12:30 AM

Quote:

Originally posted by Tom Bavis
I bought a 407 at a hamfest for $15, replaced the leaky bumblebee caps ... a FINE piece of electronics.

Design your amp using it, then sell it or use it for the NEXT amp design...

I bought the 407 for $7 (without tubes and came with a broken internal multi-switch) in a local flea market. I repaired the switch with epoxy and retubed for about $60 primarily from ebay. Just like what you said, had to replace a leaky bumblebee capacitor (1 uF) and one bad 1% wirewound resistor. It works very well since.

My main questions is, if it is such a good power supply, why not use it directly in audiophile tube amp projects to achieve good results? People have spent lots of money in diy amp parts and why not made use of these vintage equipments? Would that not be better than power supplies in a Marantz 9 or Mcintosh XYZ, which cost big bucks? Some people say that the regulator tubes will bring in unwanted noise to the system. In terms of audiophile (interpret this anyway you want) applications what are the cons?

(PS: I also have a Kepco 815 regulated supply, bigger in size and more expensive ($20 from a local flea market) but fully tubed except for a 5R4GY. That is why I think may be I can use one of them as a
builtup platform for a tube amp for own use).

tubelab.com 3rd May 2006 01:12 AM

Quote:

I bought a 407 at a hamfest for $15, replaced the leaky bumblebee caps and sold it for $175.
I know, I bid on that one, and was sniped in the last few seconds. I later found the one that I currently use. I only blew the dust out of it and plugged it in. I t works, and is currently powering a screen driven 6AV5 P-P test amp that cranks out 80 WPC. That amp needs the 555 volts. It runs close to class B which demands a power supply with a low source impedance.

I usually use the Knight power supply for amp development because it is much smaller. I have used it for development of at least 6 amp designs including the TubelabSE. It takes a good power supply to rival the sound quality that the Knight supply provides.

I have a friend who used an Eico power supply to build a Bugle 45 amp. He then built the power supply for the Bugle 45 using Electra-Print transformers and chokes. He decided that the Eico sounded beter, and he still uses it.

arnoldc 3rd May 2006 01:40 AM

Quote:

I have a friend who used an Eico power supply to build a Bugle 45 amp. He then built the power supply for the Bugle 45 using Electra-Print transformers and chokes. He decided that the Eico sounded beter, and he still uses it.
Because the EICO is regulated? Maybe he should build a regulated power suppl y for the Bugle 45.


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