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Replacing the power amp board with ICEpower

#41
For what its worth, about 15 years ago I built a 1000 watt B-15. That's a B15 clone front end incuding the phase inverter using 6sl7 tubes feeding an ICEpower 1000asp. It weighs about 13 lbs. in a 2 space aluminum rack case. The power is off the charts. I still have it and really want to do a thread here with pics and a description of the build but I am a world class procrastinator. Just an aside - the mojo of the B-15 is not available in the ext. out. of the amp, thats why I included the phase inverter section.
 
#42
larrysb said:
I'm guessing the obsolete Sanken package.

Maybe 2SC5200OTU from OnSemi and its compliment 2SA1943?

Or MJ21195G / MJ21196G in metal TO3 package?

Seems like a nice roomy amp cabinet, probably ameniable to modding to accept a different transistor package. A few tweeks of the amp circuit and it should be good to go.
Click to expand...
The challenge is SOA, that was the benefit of the gull wing package combined with the mechanical geometry of the pin out. TO3 performance in a plastic package with 2 screw attachment and easier terminal routing.
 
#43
Thumpin6string said:
I know that. I was talking about the power amp I want to replace with the ICE.
Click to expand...
I know, which is why I was commenting that neither the WT300 or WT400 used ICE power modules. The ICE modules are class D power and that was not used in either of those early Eden amps. I gave you the model numbers of the amps that did use them, which were the WTX series, not the WT series.

Thumpin6string said:
It is the same power amp used in the Eden WT300 and 400 and the Thunderfunk 420.
Click to expand...
Above is the quote from what you said. Perhaps I misunderstood what you meant. From this it sounds like the class D power module is the same one used in the Eden WT300 and WT400, which it isn't. Sorry if I misunderstood. Did you mean that you want to use an ICE power module on either a WT300 or WT400?? What did mean by this?

If you already have a WT300 or WT400 and you want that preamp to work with an ICE power module, you'd be better off running a DI out of the Eden amp to the input of a class D amp that does NOT have a preamp. You could also run a 1/4" instrument plug from the effects out of either of the old Eden amps into the effects-return/in of a new class D amp to bypass that amp's preamp.

I would not try to replace the class A/B power supply with a class D ICE power module because the power section is not designed to handle class D power supply but rather class A/B power supply, which come into the power section from a toroidal transformer and a number of capacitors and other electronics. You'd be trying to match 1970's/1980's designs with 2023 designs and they are vastly different.
 
#44
Rip Van Dan said:
I know, which is why I was commenting that neither the WT300 or WT400 used ICE power modules. The ICE modules are class D power and that was not used in either of those early Eden amps. I gave you the model numbers of the amps that did use them, which were the WTX series, not the WT series.


Above is the quote from what you said. Perhaps I misunderstood what you meant. From this it sounds like the class D power module is the same one used in the Eden WT300 and WT400, which it isn't. Sorry if I misunderstood. Did you mean that you want to use an ICE power module on either a WT300 or WT400?? What did mean by this?

If you already have a WT300 or WT400 and you want that preamp to work with an ICE power module, you'd be better off running a DI out of the Eden amp to the input of a class D amp that does NOT have a preamp. You could also run a 1/4" instrument plug from the effects out of either of the old Eden amps into the effects-return/in of a new class D amp to bypass that amp's preamp.

I would not try to replace the class A/B power supply with a class D ICE power module because the power section is not designed to handle class D power supply but rather class A/B power supply, which come into the power section from a toroidal transformer and a number of capacitors and other electronics. You'd be trying to match 1970's/1980's designs with 2023 designs and they are vastly different.
Click to expand...
The A.M.P amps used the same power amp as the Eden WT300, 400, 500, 800 and the early Thunderfunks. That was my point. If I could find a power amp from any of those, I could fix my A.M.P., but since they are all obsolete, I'm looking at doing the ICE mod if possible.
 
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#47
agedhorse said:
The challenge is SOA, that was the benefit of the gull wing package combined with the mechanical geometry of the pin out. TO3 performance in a plastic package with 2 screw attachment and easier terminal routing.
Click to expand...


Yeah, the Sanken parts were nice with the big package back in the day. They discontinued the package style a number of years ago.

But if you really need the SOA, the The MJL3281AG and MJL1302AG pair actually would do it all. It's a current part and not terribly expensive (though it seems to be back ordered at the usual places...)

MJL3281A

The O.P. has the A.M.P. model 220, which is the same board as the 420, but lower power output version with a lower voltage power transformer. I think they're the same exact amp board, just reduced power in the 220 with the lower power supply voltage.

Schematic here:

www.epanorama.net

I think it would be pretty simple to sub the newer TO3-P transistors, probably nothing more than drilling a hole for the mounting screw in the heat sink.

Or just disable the power amp and use the amp's line out send to another power amp in a rack and you're back in business if you don't mind lugging the weight.

Personally, I'd just fix the amp with newer transistors and forget about sourcing the originals. No need to go through that ripoff process.
 
#48
Thumpin6string said:
The A.M.P amps used the same power amp as the Eden WT300, 400, 500, 800 and the early Thunderfunks. That was my point. If I could find a power amp from any of those, I could fix my A.M.P., but since they are all obsolete, I'm looking at doing the ICE mod if possible.
Click to expand...
OK, now I think I understand what your saying. Your A.M.P. amps use a class A/B power sections. Those power sections though are not really modular enough to just pull out of one class A/B amp and drop it into another - not "plug and play". So you're hoping a class D ICE Power Module can be dropped in to make it work again.

I actually see there is an A.M.P. TH-420 for sale on Reverb for 0 right now if that helps. Might be less expensive than the changes you'd have to make to get satisfactory performance out of an amp that wasn't originally designed to use class D power.
 
#49
larrysb said:
Yeah, the Sanken parts were nice with the big package back in the day. They discontinued the package style a number of years ago.

But if you really need the SOA, the The MJL3281AG and MJL1302AG pair actually would do it all. It's a current part and not terribly expensive (though it seems to be back ordered at the usual places...)

MJL3281A

The O.P. has the A.M.P. model 220, which is the same board as the 420, but lower power output version with a lower voltage power transformer. I think they're the same exact amp board, just reduced power in the 220 with the lower power supply voltage.

Schematic here:

www.epanorama.net

I think it would be pretty simple to sub the newer TO3-P transistors, probably nothing more than drilling a hole for the mounting screw in the heat sink.

Or just disable the power amp and use the amp's line out send to another power amp in a rack and you're back in business if you don't mind lugging the weight.

Personally, I'd just fix the amp with newer transistors and forget about sourcing the originals. No need to go through that ripoff process.
Click to expand...

Sometimes it’s pretty easy to retrofit the TO294 package but sometimes it’s not, depending on what’s behind the new hole. Fortunately the pin out is the same.
 
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#51
That's cool. Hope it works out.

I'd love to own an AMP, or a Thunderfunk, but I do worry about break-down and repair.
I had an AMP BH420 go south on me -- years ago, of course. I think someone fixed it, but can't remember.
Also had a Thunderfunk with a problem, and had a hard time getting that problem sorted out.
 
#52
UPDATE: The amp is fixed and back up and running after being dead for 2 years. A big thank you to TBer Hand slap for bringing my A.M.P BH220 back from the dead. If you need an amp fixed, contact this guy. He does excellent work and is a nice guy too. He also treats you fairly. I'm glad I found an awesome amp tech for any future repairs.
 
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