Good day, I have a NAD 2030 amp with one channel down, I was wondering if I can replace the transistors (MJ2955/2N3055 (all four)) with MJ21195/6 ? What should I look for to know whether transistors are interchangeable?
I think better in this case to take MJ21193/4.
Myself use replacement TIP2955/TIP3055 in my simulator.
It is not much to gain to use faster devices. Try to make it as similar as possible.
This will avoid a mismatch in quality. And work the best.
Myself use replacement TIP2955/TIP3055 in my simulator.
It is not much to gain to use faster devices. Try to make it as similar as possible.
This will avoid a mismatch in quality. And work the best.
If this is the NAD amp where there are no emitter resistors, you will need to add them or it will not be thermally stable. 0.33 ohm 3W resistors will work.
jaycee there are emitter resistors with the values you mentioned.
lineup I can find MJ21195/6 pretty easy, so I suppose I can use them? I know it is a bit of an overkill 😛
lineup I can find MJ21195/6 pretty easy, so I suppose I can use them? I know it is a bit of an overkill 😛
ok, i couldnt remember which NAD amp just used plain old 2955/3055 with none 🙂
To be honest yes, the MJ21195/6 should be fine, even MJ15024/5 will be good 🙂
One thing NAD often do is use fixed resistors for bias. You may have to change that as the biasing will be different on the newer transistors. If there's a pot, then you're fine 🙂
To be honest yes, the MJ21195/6 should be fine, even MJ15024/5 will be good 🙂
One thing NAD often do is use fixed resistors for bias. You may have to change that as the biasing will be different on the newer transistors. If there's a pot, then you're fine 🙂
MJ15015 and 16 datasheet refers to the 3055-2955 spec. They have a higher Vceo and an actual SOA, not as big as 21195. I got my On Semi versions for $1.28 each from farnell (newark in USA). Depending on layout, you might have to put 10-20 pf across the B-E leads to prevent oscillation, especially on the MJ15016 which has ft of 4 mhz. The MJ15015 ft is .8 mhz.
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If there is no bias pot, you want something close to the original 3055/2955. MJ21195/6 would *work*, but the bias would need to be adjusted if possible. MJ15015/16 are much closer to the Moto/ON 3055 (only slightly larger die with the same layout and processing) so the bias should be closer to correct without adjustment. The extra 10-20 pF cap trick may be needed regardless of what type is used if they are not the originals.
Hi all, I have same situation with zacko...
I will try to use TIP2955/TIP3055
Btw... I'm sorry for bad english 😀
I will try to use TIP2955/TIP3055
Btw... I'm sorry for bad english 😀
or choose any you like but add a trimmer to the bias circuit and you know exactly what are you doing
done it a million times for both pioneer and kenwood amps that featured no trimers in the bias circuit ...
benefit of the above could be the possibility of beefing up the bias at a desirable level ( dont realy think that will make the NAD any better but just in case )
Off topic
at the time this was all of course carbon cheap resistors the tracking though and tollerance after 30-40 years of operation was unbelivable ...talk about excellent use of available parts at the time.... amazing japanese made products !!!
done it a million times for both pioneer and kenwood amps that featured no trimers in the bias circuit ...
benefit of the above could be the possibility of beefing up the bias at a desirable level ( dont realy think that will make the NAD any better but just in case )
Off topic
at the time this was all of course carbon cheap resistors the tracking though and tollerance after 30-40 years of operation was unbelivable ...talk about excellent use of available parts at the time.... amazing japanese made products !!!
Or you could just put the correct 2N3055/MJ2955 parts in! Very easily obtained and at only 20WPC not really under any stress 😀
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