I dug around in my computer graveyard and could only come up with square or rectangular ones… hum, I really wanted a round one. I remember helping a friend in Florida with some LED spotlights that had round heatsinks, and after poking around on Mouser, I found one. Mouser #: 941-LMH020HS001, Mfr. #: LMH020-HS00-0000-0000001, Desc.: Heat Sinks - LEDHeat Sink for LMH02. Stock it was a little tall, kinda dwarfed the pentodes. After sawing them in half I think it looks good.
Not a mirror, just polished the aluminum plate. I used to polish aluminum bits on my motocross bikes, and though it would look good on the amp (this kept spectators focused on the bling rather than my slow riding). It took about 5-6 hours to polish… I’ll never do it again. I need to improve my technique, have it professionally done or get the thing anodized.
I’ll run it stock for a while before trying any modifications, but I would like to try later in the year if I can figure out an easy’ish plan. If it’s not too much trouble I’d really appreciate a not so radical builder’s cliff’s notes on increasing the horsepower… just a bit. Remember my skill level (beginner). I could really use straight forward directions like: change 6JN6 tube to ABC, change diode 123 to 456, etc.
P-P Engineer Amp pushed to 70WPC : a novice resume
Hello all, three months ago finished a TSE with 300B (before that there was Pete’s low-mu preamp), and even if have other four amplifier decided I‘d need to build a new one
, looking around discovered this HUGE thread and went through all of it just to decide that what I want is an “engineer amp” capable of 70-80 WPC.
Have to say I’m not an expert, can solder and follow instructions and all the stuff but have not a real knowledge in tube electronics, so all 149 pages of this thread, with lots of tubes and different configurations and possible B+ got me in complete confusion.
What do I need to have a 70WPC red board modifying the least?
Tubes : 6HJ5 (power) , drivers (???)
Mod to the board : the one proposed from Russ (rknize) attached
More mods : R8, R9, R10, R11 should be changed to around 470R at 2 watt. Change R29, R30, R31, R47 to 220K-3W [post #1259]
Caps to be upgraded to 500V : ??? All of them? HELP!!
Power transformer : this depend of which B+ we’are looking for. Based on your experience, should 450V B+ be ok? In this case, may the Hammond 373EX do well? (it’s the one I’ve used in TSE)
Output Transformers : think that the ones from Edcor for Pete’s Project should be good, any suggestion?
Something else left?
Thanks in advance and hope my resume will be helpful to other novices too.
Best regards
Giuseppe (Madrid)
Hello all, three months ago finished a TSE with 300B (before that there was Pete’s low-mu preamp), and even if have other four amplifier decided I‘d need to build a new one
, looking around discovered this HUGE thread and went through all of it just to decide that what I want is an “engineer amp” capable of 70-80 WPC.Have to say I’m not an expert, can solder and follow instructions and all the stuff but have not a real knowledge in tube electronics, so all 149 pages of this thread, with lots of tubes and different configurations and possible B+ got me in complete confusion.
What do I need to have a 70WPC red board modifying the least?
Tubes : 6HJ5 (power) , drivers (???)
Mod to the board : the one proposed from Russ (rknize) attached
More mods : R8, R9, R10, R11 should be changed to around 470R at 2 watt. Change R29, R30, R31, R47 to 220K-3W [post #1259]
Caps to be upgraded to 500V : ??? All of them? HELP!!
Power transformer : this depend of which B+ we’are looking for. Based on your experience, should 450V B+ be ok? In this case, may the Hammond 373EX do well? (it’s the one I’ve used in TSE)
Output Transformers : think that the ones from Edcor for Pete’s Project should be good, any suggestion?
Something else left?
Thanks in advance and hope my resume will be helpful to other novices too.
Best regards
Giuseppe (Madrid)
Attachments
Yes, that's ok, for a grounded center tap circuit. Which rectifiers?
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You could use a choke of 1H or more, as long as it can handle the DC current, and the DC voltage present.
http://www.hammondmfg.com/153.htm
http://www.hammondmfg.com/193.htm
If you don't use the specially designed Edcor XPWR139 power transformer, you'll need another transformer
to supply the -60V for the output tube current source.
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It says : "The C- supply of about -60V is generated from taps off the B+ winding, and is filtered by an RCRC filter with no regulation."
So I think just changing correspondid bleeder resistors R7 - R12 will be fine
Conclusions and line of work
Hi all, have red all the thread a second time, written some members (thanks all) asking to remember far past (5 years) events, and understood that there are three possible lines of work for the red board (assuming I’m going with 6HJ5):
1) Stock (280-50-0-50-280) : follow instruction and go on;
2) Overvoltage (320-50-0-50-320 or more) so to have a B+ of around 450 : this implies that power supply capacitors have to go from 450 to 500V, stronger diodes, more wattage resistors : the “plus” voltage goes through all the board;
3) The “sum” method that is going with a more or less stock configuration and later add a second power transf. directly on the plates (http://www.diyaudio.com/forums/tubes-valves/151206-posted-new-p-p-power-amp-design-109.html)
I’m going to do a mix of (2) and (3) :
a) Reinforce capacitors, resistors and diodes (should not harm)
b) Go for a first version with a little overvoltage stock : 300-50-0-50-300 , this will be done with a custom toroidal; same for OPT, custom 50W 4K toroidal OPTs;
c) When assured that “normal” is working and if needed, should be easy add a second toroid to configure like I post #1087
What do you think?
Does point (a) make sense or could go with completely stock configuration?
Thanks a lot
giuseppe
Hi all, have red all the thread a second time, written some members (thanks all) asking to remember far past (5 years) events, and understood that there are three possible lines of work for the red board (assuming I’m going with 6HJ5):
1) Stock (280-50-0-50-280) : follow instruction and go on;
2) Overvoltage (320-50-0-50-320 or more) so to have a B+ of around 450 : this implies that power supply capacitors have to go from 450 to 500V, stronger diodes, more wattage resistors : the “plus” voltage goes through all the board;
3) The “sum” method that is going with a more or less stock configuration and later add a second power transf. directly on the plates (http://www.diyaudio.com/forums/tubes-valves/151206-posted-new-p-p-power-amp-design-109.html)
I’m going to do a mix of (2) and (3) :
a) Reinforce capacitors, resistors and diodes (should not harm)
b) Go for a first version with a little overvoltage stock : 300-50-0-50-300 , this will be done with a custom toroidal; same for OPT, custom 50W 4K toroidal OPTs;
c) When assured that “normal” is working and if needed, should be easy add a second toroid to configure like I post #1087
What do you think?
Does point (a) make sense or could go with completely stock configuration?
Thanks a lot
giuseppe
50watt 4k transformers are not right for the output.
Your best best is to get 100-150 watt transformers with multi output combination so you can load the unit with either 6.6k or 3.3k by selecting 4 ohm or 8 ohm ouput.
I still think the easiest is to just to rig it with the 6HJ5, set the output to 400v B+, and select a 3.3k output transformer. That will give you 75 watts without having to worry about 500v caps and you wont have to bother with a external booster supply for the plates. I see no reason why you would need another 2.0db head room to move the full on 120watt version.
And 450v with a 4k tap will give you the same output as the combo i just listed.
Your best best is to get 100-150 watt transformers with multi output combination so you can load the unit with either 6.6k or 3.3k by selecting 4 ohm or 8 ohm ouput.
I still think the easiest is to just to rig it with the 6HJ5, set the output to 400v B+, and select a 3.3k output transformer. That will give you 75 watts without having to worry about 500v caps and you wont have to bother with a external booster supply for the plates. I see no reason why you would need another 2.0db head room to move the full on 120watt version.
And 450v with a 4k tap will give you the same output as the combo i just listed.
Hi All,
How snug should the plate caps fit? It's my first time using them and I'm a little unsure with what I got.
I just finished my amp, using the 6JM6's, and when I popped tubes in I found that the plate caps fit a bit on the sloppy side. I confirmed that I bought the right ones (the miniature/ .25" jobbies from Pacific TV) and that they shipped the right ones. I got out the calipers and both the caps and the tubes measure about right, so I'm not really sure what I'm missing here.
Is there some way to tighten up the fit, or should I try a different lot from a different vendor? I'd appreciate any advice.
Regards,
John
How snug should the plate caps fit? It's my first time using them and I'm a little unsure with what I got.
I just finished my amp, using the 6JM6's, and when I popped tubes in I found that the plate caps fit a bit on the sloppy side. I confirmed that I bought the right ones (the miniature/ .25" jobbies from Pacific TV) and that they shipped the right ones. I got out the calipers and both the caps and the tubes measure about right, so I'm not really sure what I'm missing here.
Is there some way to tighten up the fit, or should I try a different lot from a different vendor? I'd appreciate any advice.
Regards,
John
Couldn't get my first set of top caps to work, but the second set work just fine. Amp has been up and running for a week or so. All the voltage came up fine and not a ton of finagling to get the balance close.
Not too much to note about my build -- I used ElectraPrint outputs, Edcor power transformer, stuck in a 100k pot because I have plenty of gain and short interconnects, hardwired the power cord, and relocated the rca jacks to the front. Top plate is from FrontPanel Express (should have put in more room between the PCB and the output transformers, but not too bad). No heatsinks, but the top plate doesn't get warm at all (it's 4mm aluminum). Very nice sounding amp. The one thing I really notice is how quiet it is -- it's REALLY quiet; clearly my from-scratch builds have a ways to go... Thanks Pete for the excellent design and great boards.
Regards,
John
Not too much to note about my build -- I used ElectraPrint outputs, Edcor power transformer, stuck in a 100k pot because I have plenty of gain and short interconnects, hardwired the power cord, and relocated the rca jacks to the front. Top plate is from FrontPanel Express (should have put in more room between the PCB and the output transformers, but not too bad). No heatsinks, but the top plate doesn't get warm at all (it's 4mm aluminum). Very nice sounding amp. The one thing I really notice is how quiet it is -- it's REALLY quiet; clearly my from-scratch builds have a ways to go... Thanks Pete for the excellent design and great boards.
Regards,
John
Attachments
Hello everyone:
I just finished stuffing the "Big Red Board" (BRB ). The build is completely stock (only thing R21 is still 4.7K with just a bit bigger dissipation at 7W instead of 5 W).
In an timid effort to get a little more out, instead of the Edcor XPWR139 (280-50-0-59-280), I ordered a XPWR205 (300-50-0-50-300). This should give me a bit higher B+ (perhaps 10% higher). Not enough to worry about caps, I think.
For output transformer, I think I may have been too "optimistic". I ended up ordering a pair of CXPP60-8-6.6K . I don't think I am going to see 60 WPC, but in the future, should I make more mods, I should be set.
Do you think I'll see about 40 WPC ?
Marco
I just finished stuffing the "Big Red Board" (BRB
). The build is completely stock (only thing R21 is still 4.7K with just a bit bigger dissipation at 7W instead of 5 W).In an timid effort to get a little more out, instead of the Edcor XPWR139 (280-50-0-59-280), I ordered a XPWR205 (300-50-0-50-300). This should give me a bit higher B+ (perhaps 10% higher). Not enough to worry about caps, I think.
For output transformer, I think I may have been too "optimistic". I ended up ordering a pair of CXPP60-8-6.6K . I don't think I am going to see 60 WPC, but in the future, should I make more mods, I should be set.
Do you think I'll see about 40 WPC ?
Marco
Oh yeah, I read a lot of the posts. is that I am simply not savvy enough to run this thing with a 600V B+ and changing components on the fly, nor I have large transformers and /or power supplies to try.
But I have seen suggestions that a modest increase in B+ coupled with lowering the impedance of the OPT can help. We'll see when the transformer get here.
Marco
But I have seen suggestions that a modest increase in B+ coupled with lowering the impedance of the OPT can help. We'll see when the transformer get here.
Marco
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