The description says Materialabschluss natur which I presume means that the aren't anodized. Thus they are only good for forced cooling b/c their emissivity is low.
You are looking for heatsinks that are anodized (eloxiert) in any color.
tme lets you search heatsinks by thermal resistance. If you want to stay, say, 20K above ambient and each FET dissipates 30W you are looking for a heatsink <0.75K/W for one FET or <0.375/W for two.
Having said that, heatsinks have higher thermal resistance when they get warm...
You are looking for heatsinks that are anodized (eloxiert) in any color.
tme lets you search heatsinks by thermal resistance. If you want to stay, say, 20K above ambient and each FET dissipates 30W you are looking for a heatsink <0.75K/W for one FET or <0.375/W for two.
Having said that, heatsinks have higher thermal resistance when they get warm...
Thanks.
That would help me a lot.
I have the Fischer 300x150x83, non anodized, first tested on F4 and now fixed the Aleph J- i could learn that way higher thermal resistance when they get warm.
Same way with 0,56K/W on hard biased ACA.
Will search again and give them a try if it's ok- or found an other doing the job.
That would help me a lot.
I have the Fischer 300x150x83, non anodized, first tested on F4 and now fixed the Aleph J- i could learn that way higher thermal resistance when they get warm.
Same way with 0,56K/W on hard biased ACA.
Will search again and give them a try if it's ok- or found an other doing the job.
Nutz, may have smoked my first M2? or turned into a chainsaw sound imitator!
This amp has performed flawlessly since its building. I carried the Amp from the downstairs main system to my upstairs vinyl system. Flipped on the Pearl 2, BA3 front end. In a couple minutes flipped on the M2 and went downstairs to bring up a few things and let the amp warm.
In a few minutes I heard a chainsaw or Harley davidson outside. Went to the door, noticed it was coming from upstairs! Yep my system sounded like a Harley idling outside. Immediately flipped it off, and stuck another amp (F6) in its place and put on an album, just fine.
Take M2 downstairs, remove cover, careful inspection, nothing obvious, no burned resistors etc. Placed shorting plugs in the inputs, removed speaker wires already. multimeters all around, bias and output and fired it up. I never measured from cold but there were some odd begining bias numbers.
Let it heat up, normal heat, so good. Both R & L channels measured .684 and .678 v. Offset, a little improved, right channel, (easily adjusted to 0 or below .2 mv.) Left channel, which when I built it ran out of twist before I could zero, but fine at 2-3 mv.
After warm up on test table/dining room table, these numbers seem to hold, which looks pretty darn normal. My speakers, although making chainsaw/Harley Davidson noise dont seem to be damaged, 6 1/2" 2 way 85 dB efficiency stand mounted mini monitors.
I guess I will hook up test speakers if it keeps being normal.
Question: WHAT HAPPENED? I will be back shortly if amp does anything weird, or plays normal, which I dont think it will.
Russellc
This amp has performed flawlessly since its building. I carried the Amp from the downstairs main system to my upstairs vinyl system. Flipped on the Pearl 2, BA3 front end. In a couple minutes flipped on the M2 and went downstairs to bring up a few things and let the amp warm.
In a few minutes I heard a chainsaw or Harley davidson outside. Went to the door, noticed it was coming from upstairs! Yep my system sounded like a Harley idling outside. Immediately flipped it off, and stuck another amp (F6) in its place and put on an album, just fine.
Take M2 downstairs, remove cover, careful inspection, nothing obvious, no burned resistors etc. Placed shorting plugs in the inputs, removed speaker wires already. multimeters all around, bias and output and fired it up. I never measured from cold but there were some odd begining bias numbers.
Let it heat up, normal heat, so good. Both R & L channels measured .684 and .678 v. Offset, a little improved, right channel, (easily adjusted to 0 or below .2 mv.) Left channel, which when I built it ran out of twist before I could zero, but fine at 2-3 mv.
After warm up on test table/dining room table, these numbers seem to hold, which looks pretty darn normal. My speakers, although making chainsaw/Harley Davidson noise dont seem to be damaged, 6 1/2" 2 way 85 dB efficiency stand mounted mini monitors.
I guess I will hook up test speakers if it keeps being normal.
Question: WHAT HAPPENED? I will be back shortly if amp does anything weird, or plays normal, which I dont think it will.
Russellc
With inputs still shorted, hooked up a speaker. No Harley Chainsaw noises, either channel. This was a speaker with maybe 87 dB efficiency. I could, with ear very close to the driver, hear a slight hum. Not objectionable, but I never noticed any hum with a speaker of this lower efficiency, and having to stick ear in woofer to hear slightest hum, couldnt hear it a few inches away. 
Time to hook up a pre and play music...and I will be back.
What would cause such a bizarre occurrence? Is this "motor boating"? Never actually experienced it before to know what it is.
Russellc
Time to hook up a pre and play music...and I will be back.
What would cause such a bizarre occurrence? Is this "motor boating"? Never actually experienced it before to know what it is.
Russellc
Back in system, all "seems" normal. I have no idea what caused this. I have never had this sort of racket from an amp that wasnt cooked.
I really figured this would have at least smoked the outputs, but music plays.
Will make sure this was an abnormality before putting back in downstairs system, where my new Tektons reside....really dont want to smoke their drivers.
Russellc
I really figured this would have at least smoked the outputs, but music plays.
Will make sure this was an abnormality before putting back in downstairs system, where my new Tektons reside....really dont want to smoke their drivers.
Russellc
I once experienced this situation in one of my diy amp like you. Doing that famous ctrl+alt+del (power off reboot) I learned working in IT made the problem disappear. No any damage speakers or any components and it still played well, until now. Since then I could not reproduce the problem. I guess my not so nice wiring, unsure grounding issue, mains noise, etc. were to blame or probably amp oscilation.
) I learned working in IT made the problem disappear. No any damage speakers or any components and it still played well, until now. Since then I could not reproduce the problem. I guess my not so nice wiring, unsure grounding issue, mains noise, etc. were to blame or probably amp oscilation.
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Yes, I think the bias thing is explained by the class c,b,a thing. I have run this amp for months with no issues, nor can I replicate...
Control, Alt delete!
Russellc
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easy to test is it same thing - while amp is singing - power it off and do not touch volume
after 10 or so min. , with music playing , power amp on
first you'll hear nothing , then slightly muted crackling sounding music , then more and more like it should sound
you'll know is that what startled you , or is it something else
after 10 or so min. , with music playing , power amp on
first you'll hear nothing , then slightly muted crackling sounding music , then more and more like it should sound
you'll know is that what startled you , or is it something else
Elevated pulse did happen, pre and Pearl on first, then switched on M2 with no music going through. As it warmed up over 5-10 mins I suddenly heard noise.
I can fix M2. Lots of spares if necessary. Also, pre was not switched to Phono, selector was turned to an input that had shorting plugs.
Russellc
I can fix M2. Lots of spares if necessary. Also, pre was not switched to Phono, selector was turned to an input that had shorting plugs.
Russellc
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I also had an interesting issue with my M2. I had been using an akido tube preamp(9 pin all in one). I had problems with excessive voltages from the pre at turn on blowing the jfets over time even when the amp was not powered on. Other than that everything sounded great. I installed a voltage clamp using zener 10v diodes following the guideline over at rod Elliott's site. I repaired the M2 and it worked perfectly with a lesser quality SS pre, but when I tried using the clamped aikido with the M2 the sound is all terribly garbled. Changed back to SS pre all is well again. When I use the clamped Aikido with my aleph J no problem sounds great. Maybe it throws the M2 into occillation. My solution is to build Salas's new pre for the M2
I was having "elevated pulse" plus freak out, but I am fairly certain it was both? Made me wonder if power supply at fault?
Russellc
well , I admit that my brain is little short there ; definitely Pa time
I can't see that M2 , not having NFB , can oscillate
also - having 100k input imp.vs. 200++K of Aleph J input impedance ........ also M2 having lesser gain
Gremlins must be in it, working fine, I tried to blame something up stream, maybe loose Rca jack on pre & power interconnect, didn't buzz until amp began to pass juice, then noise? After all, I did change them out and remove and reinstalled inter connect? while mistake can be made, I solder carefully on boards, making sure it is nice shiny "volcanos" and check other side for a little flow though. Power supply is made with Tea's PS board, Panasonic caps. I also wondered if some left over piece of wire, solder, or other metal tidbit was in case. It could have dislodged and caused some funky problem...then moving to repair area it fell from problem area?
No music playing when this happened...it was just warming up at time of Harley-chainsaw. It really sort of sounded like a Harley or Chainsaw idling at a distance outside....but no Harley upstairs, or chainsaw. Tiny brain of mine doesn't help!
All seems well now...
Russellc
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