Hi all,
I have two Infinity Reference subwoofers. Each is rated at 300W RMS, 4 ohm and 90dB.
I am thinking of the PA300 or the ETI466 to power them. One of the main problems is that the MJ15003/4 devices are not available easily in India. Moreover, there is a huge problem with fake transistors. Could I replace them with 2N3773/ 2N6609 (140V, 16A)? The latter devices are available more easily.
Secondly, will either of these amps be good for HT subwoofer duties? I will be grateful if any of you could share your thoughts.
Cheers,
Vivek
I have two Infinity Reference subwoofers. Each is rated at 300W RMS, 4 ohm and 90dB.
I am thinking of the PA300 or the ETI466 to power them. One of the main problems is that the MJ15003/4 devices are not available easily in India. Moreover, there is a huge problem with fake transistors. Could I replace them with 2N3773/ 2N6609 (140V, 16A)? The latter devices are available more easily.
Secondly, will either of these amps be good for HT subwoofer duties? I will be grateful if any of you could share your thoughts.
Cheers,
Vivek
Hi djk,
Thanks for the reply.
The 3773/ 6609 are easily available in India. The stuff is good too and that is why I want to use them. But I understand the sound quality changes in the PA300 with changes in the output transistor. I hope it does not worsen.
Also, I have built several small amps but am not experienced in modifying circuits. How I would be able to accommodate three pairs I don't know.
Vivek
Thanks for the reply.
The 3773/ 6609 are easily available in India. The stuff is good too and that is why I want to use them. But I understand the sound quality changes in the PA300 with changes in the output transistor. I hope it does not worsen.
Also, I have built several small amps but am not experienced in modifying circuits. How I would be able to accommodate three pairs I don't know.
Vivek
Apart from ON Semi MJ15003, I believe BEL Bangalore also makes MJ15003 under license (datasheet is available on the BEL website), but I have no idea about how it stacks up against the original in SOA, etc. Also, only the NPN is available, not the complement.
There are a lot of cheap Chinese 2N3773s around, so be careful about the quality. If you find an inexpensive, high-quality, large-die clone, let me know where it's available.
The safest pair now available is the original Toshiba 2sa1943/2sc5200 from Chetan or Darshan, but it's not TO-3, if that's important to you.
There are a lot of cheap Chinese 2N3773s around, so be careful about the quality. If you find an inexpensive, high-quality, large-die clone, let me know where it's available.
The safest pair now available is the original Toshiba 2sa1943/2sc5200 from Chetan or Darshan, but it's not TO-3, if that's important to you.
" I hope it does not worsen."
Bryston used the 2N3773/6609 for many years in their top amplifiers.
Just make sure they are the 4Mhz epitaxial (a few companies still make the slower hometaxial types for power supplies).
Bryston used the 2N3773/6609 for many years in their top amplifiers.
Just make sure they are the 4Mhz epitaxial (a few companies still make the slower hometaxial types for power supplies).
there's that recommendation again.djk said:
How do we tell them apart?
A real 3773 is a great transistor.
Nordic, I guess that just about settles it. I suppose it is not going to be like the difference between a tube and a SS amp.
Siva, I have the datasheet of the BEL-made MJ15003. But the problem is not having the MJ15004. I could try in other shops but I may still end up getting a fake.
Also, both amps I am thinking of building use TO-3 case output transistors. I have also replied to your e-mail regarding this. But if I get a good 300W/ 4 ohm amp, I don't really care about which transistors it uses. I should probably go to and pick up the transistors. They probably will have the 3773/ 6609 as well because CDIL manufactures them in India.
Which shop is better - Darshan or Chetan?
djk, getting good transistors in India is so difficult because the DIY market is very small. So, we just have to pick up what we find. It's that bad at times. Nevertheless, now that you have mentiond the 4MHz types, I will look out for them.
However, will using the older transistors cause any problems during the operation of the amplfier?
Just like Andrew, I too would like to know.
Cheers,
Vivek
Siva, I have the datasheet of the BEL-made MJ15003. But the problem is not having the MJ15004. I could try in other shops but I may still end up getting a fake.
Also, both amps I am thinking of building use TO-3 case output transistors. I have also replied to your e-mail regarding this. But if I get a good 300W/ 4 ohm amp, I don't really care about which transistors it uses. I should probably go to and pick up the transistors. They probably will have the 3773/ 6609 as well because CDIL manufactures them in India.
Which shop is better - Darshan or Chetan?
djk, getting good transistors in India is so difficult because the DIY market is very small. So, we just have to pick up what we find. It's that bad at times. Nevertheless, now that you have mentiond the 4MHz types, I will look out for them.
However, will using the older transistors cause any problems during the operation of the amplfier?
Just like Andrew, I too would like to know.
Cheers,
Vivek
Hi all,
I just bought 2N3773s from a shop today. The shop I bought it from is a reputed one and the shopkeeper assured me that they are genuine On Semi transistors.
I came home and used nail polish remover and the marking began to rub off after some really hard rubbing. The liquid does not contain acetone but ethyl acetate, isopropyl alcohol, estasol, panthenol, tocopheryl acetate etc etc. Now, with so many chemicals in it, is it natural or am I possibly looking at counterfeit transistors. I could open up one but I don't want to unless there is really no other way I can tell.
Pics attached.
I just bought 2N3773s from a shop today. The shop I bought it from is a reputed one and the shopkeeper assured me that they are genuine On Semi transistors.
I came home and used nail polish remover and the marking began to rub off after some really hard rubbing. The liquid does not contain acetone but ethyl acetate, isopropyl alcohol, estasol, panthenol, tocopheryl acetate etc etc. Now, with so many chemicals in it, is it natural or am I possibly looking at counterfeit transistors. I could open up one but I don't want to unless there is really no other way I can tell.
Pics attached.
Attachments
If they are genuine ON Semiconductor they will be 4Mhz, they discontinued the slow parts years ago.
RCA (and others) made both slow and fast 3773s, Newark used to list both in the catalog. I only bought Motorola (which at that time only made the 4Mhz devices), so I couldn't tell you how the RCAs were marked. I did buy some Solitron 3773 that were so slow they wouldn't work in a BGW 750, hence the word of caution.
I would buy one extra part from your supplier and cut it open to make sure it's real, the $3 you waste is cheap insurance.
RCA (and others) made both slow and fast 3773s, Newark used to list both in the catalog. I only bought Motorola (which at that time only made the 4Mhz devices), so I couldn't tell you how the RCAs were marked. I did buy some Solitron 3773 that were so slow they wouldn't work in a BGW 750, hence the word of caution.
I would buy one extra part from your supplier and cut it open to make sure it's real, the $3 you waste is cheap insurance.
Yes! Yahoo! Yipeeee! Hooray!!!!!!!!! I am delighted. Thank you. I paid 65 rupees for each transistor (1 USD is approx 38 rupees). So I suppose it is a good deal. I will stock up with a dozen or so from the same store. but I did not find 2N6609 to go with them. Don't know what to do about that.
Vivek.
Vivek.
Vivek said:
Pray. Pray that you will find a dealer who has some NOS. ON no longer makes them - the last two batches I got were one pre-ON Motorola in about '96, and I ended up settling for some Mospec 2N6609's a couple years later. Those were good too, but now even those have dried up.
Couple of options....
1) use MJ15025's if you can get them
2) make the amp QC (all NPN) if it will tolerate it without oscillating
3) keep digging - especially in the suplus market. If you choose this option, your best bet will be old 80's date-coded devices in the aluminum TO-3. Less likely to be fakes. I wouldn't trust a source of 'new' 2N6609's any further than I can throw it.
MJ15024,15025 would be what i would use, or better still,MJL1302,3281. since subwoofers have most of the harmonic energy filtered out by their limited frequency response, go with the 15024,25 pairs which are less expensive.
Hi vivek,
Even i am planin to build a sub amp.
I was planin to go for the Rod elliot 300w amp but it seems that the MJL and MJE transistors are not available here in Pune.
Could u please tell which amp are u planin to build u know the schematics?
And ofcourse it will be quite helpfull as u seem pretty knowledgable and know the alternative parts ...
And since we are at it .. do u happen to know any alternatve transistors for MJL4302a/4381a , MSA42 , MJE15033?
If u know any other circuits please provide the info ...
Even i am planin to build a sub amp.
I was planin to go for the Rod elliot 300w amp but it seems that the MJL and MJE transistors are not available here in Pune.
Could u please tell which amp are u planin to build u know the schematics?
And ofcourse it will be quite helpfull as u seem pretty knowledgable and know the alternative parts ...
And since we are at it .. do u happen to know any alternatve transistors for MJL4302a/4381a , MSA42 , MJE15033?
If u know any other circuits please provide the info ...
Hi guys,
I will try to locate the 15024/ 25 in the electronics market but I doubt if I will find them. The 6609 is manufactured in India by a company called Continental Device India Limited. Though they may not be as good as the original On Semi devices, but I suppose they will be far better than ending up with fakes. I checked in the On Semi website and the substitution they suggest is the MJ15004.
The 3773 is widely used in UPS systems here. So I think I can be assured of a constant supply of 3773s.
Sr2002, I am still mulling the idea of the PA300 or the ETI466. For both, I need to find proper PNP transistors. If I go for something like Quasi's bipolar amp, I will need just NPN transistors.
If you are looking at the ESP 300W amp, you will have to buy the PCB from the site. I think it costs around Rs 1000 or so. For that price, we can buy all amplifier parts barring the transformer in India. I don't think it is viable. There are many, many circuits available on the internet. So, I would look around, settle for one and build my own PCBs. But if you are not up to the job of building PCBs, then you could buy it and then build. There should be kits available in Mumbai. See if you can plan a one-day trip to Mumbai and look around Lamington Road. You may find a good kit.
Regading the transistors you are looking for, you will have to keep looking in the local markets. Do a google and find some substitutes. It is painful but we do not have too many choices in India.
Right. Now that the transistor stuff is being sorted out, let us come back to my original query. I am still unable to decide between the PA300 and the ETI466. Is/ are either/ both of these good as a sub amp or am I better of building something else.
I have also got some Toshiba 2SA1943/ 2SC5200s. Maybe there is a good amp out there. Suggestions are most welcome.
Thanks,
Vivek
I will try to locate the 15024/ 25 in the electronics market but I doubt if I will find them. The 6609 is manufactured in India by a company called Continental Device India Limited. Though they may not be as good as the original On Semi devices, but I suppose they will be far better than ending up with fakes. I checked in the On Semi website and the substitution they suggest is the MJ15004.
The 3773 is widely used in UPS systems here. So I think I can be assured of a constant supply of 3773s.
Sr2002, I am still mulling the idea of the PA300 or the ETI466. For both, I need to find proper PNP transistors. If I go for something like Quasi's bipolar amp, I will need just NPN transistors.
If you are looking at the ESP 300W amp, you will have to buy the PCB from the site. I think it costs around Rs 1000 or so. For that price, we can buy all amplifier parts barring the transformer in India. I don't think it is viable. There are many, many circuits available on the internet. So, I would look around, settle for one and build my own PCBs. But if you are not up to the job of building PCBs, then you could buy it and then build. There should be kits available in Mumbai. See if you can plan a one-day trip to Mumbai and look around Lamington Road. You may find a good kit.
Regading the transistors you are looking for, you will have to keep looking in the local markets. Do a google and find some substitutes. It is painful but we do not have too many choices in India.
Right. Now that the transistor stuff is being sorted out, let us come back to my original query. I am still unable to decide between the PA300 and the ETI466. Is/ are either/ both of these good as a sub amp or am I better of building something else.
I have also got some Toshiba 2SA1943/ 2SC5200s. Maybe there is a good amp out there. Suggestions are most welcome.
Thanks,
Vivek
You might consider buying a Pass A40 board from AudioXpress.com for $6 and drive a quasi-comp output stage with your 3773s.
With suitable parts on the A40 board I have run as much as ±95V for big power out.
http://www.audioxpress.com/bksprods/products/pcbj-5.htm
I would then copy the Phase Linear 400 output stage.
With suitable parts on the A40 board I have run as much as ±95V for big power out.
http://www.audioxpress.com/bksprods/products/pcbj-5.htm
I would then copy the Phase Linear 400 output stage.
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