These will be driving NJW0281/NJW0302 outputs on a 70 w amp. The original outputs were Sanken 2SC3855/2SA1491, bdent has them, but not in matching hfe groups, so I'm going with the ON Semi subs which look quite good. Would BD139/BD140 be my best match here?
the 1358 is quite a nice driver.
There are literally hundreds of alternatives out there that could be substituted.
If the amp has low voltage supply rails then you might get away with the bd, but they are not equivalent. I would not use them.
There are literally hundreds of alternatives out there that could be substituted.
If the amp has low voltage supply rails then you might get away with the bd, but they are not equivalent. I would not use them.
better SOA and most others specs as well
avail in USA in best Y grade
KSC2690/2690A
KSA1220/KSA1220A
avail in USA in best Y grade
KSC2690/2690A
KSA1220/KSA1220A
Check that rail voltage.
70W into 8r0 and +-50Vdc does not equate, unless they have made so many price cuts that they have ruined the performance.
70W into 8r0 and +-50Vdc does not equate, unless they have made so many price cuts that they have ruined the performance.
The unit in question is a Denon PMA-520, the schematic is here:
4shared.com - document sharing - download pma520.pdf
It is suitable for 6 ohm speakers and sounds surprisingly good. I am currently using it with Snell KIII speakers, have had NHT and Paradigms on it also, always have been pleased. Not "high end", but most definitely among the better commercially available amps I have heard.
4shared.com - document sharing - download pma520.pdf
It is suitable for 6 ohm speakers and sounds surprisingly good. I am currently using it with Snell KIII speakers, have had NHT and Paradigms on it also, always have been pleased. Not "high end", but most definitely among the better commercially available amps I have heard.
Think what it will do for the clipping performance and rail sagging, I also use slightly higher rail voltages for some of my amps.
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Think what higher voltage smoothing caps and a smaller size power transformer will do for the total shipping weight.
The filter caps are 6800x4 56V. Maybe the amp's rail voltage was designed around the filter cap's "left over from another job" voltage? :0|
Not much 🙄 , one has to keep in mind these are mass produced amps, the same transformer is probably used in higher wattage amps of denons range, bulk purchase keeps the price lower, this applies to the caps as well.
I only sell a amp here and there and this works for me too, plus I have the added benefit with clipping performance. For a diyer only building a amp for himself it doesnt quite equate price wise but I prefer it to using clipping enhanching circuitry which to my ears has always degraded sound quality.
You cannot specify the Vce0 of the drivers until you know what voltages they have to operate at.
Measure the PSU first.
Measure the PSU first.
The Vceo of the originals (2SC3421/2SA1358) is 120V. The Vceo of the suggested replacement (KSA1220/KSC2690) is 120V. The rails are indicated as 50V on the schematic. Is this not good enough? Bdent has originals, but they would not match hfe group, I'm assuming is the case, have not gotten back to me yet.
There is no reason to buy the non A version. The A part is 180V but either should be fine if you choose to buy the lower voltage parts.
Hi DP,
your original question asked if a bd part would do.
It was an 80Vce0 part to replace a 120Vce0 part.
It's obvious you have not measured your amp and yet you specify inadequate replacement transistors.
your original question asked if a bd part would do.
It was an 80Vce0 part to replace a 120Vce0 part.
It's obvious you have not measured your amp and yet you specify inadequate replacement transistors.
Andrew I think he's moved on after my 1st suggestion.
I don't think Denon would specify an underrated Vceo part anyways.
I don't think Denon would specify an underrated Vceo part anyways.
Yeah, I will use original devices or the KSA1220 or A alternates. The BD part was a poor choice (that's why I posted for suggestions), but one of the cross reference sites recommended it conditionally.
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