Need a sub amp badly - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 29th April 2008, 07:09 AM   #1
Vivek is offline Vivek  India
diyAudio Member
 
Join Date: Nov 2000
Location: Bangalore, India
Default Need a sub amp badly

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
__________________
Thank God for DIY audio.
  Reply With Quote
Old 30th April 2008, 06:10 AM   #2
Vivek is offline Vivek  India
diyAudio Member
 
Join Date: Nov 2000
Location: Bangalore, India
Nobody?
__________________
Thank God for DIY audio.
  Reply With Quote
Old 30th April 2008, 07:45 AM   #3
djk is offline djk
diyAudio Member
 
djk's Avatar
 
Join Date: Feb 2001
Location: USA
The 3773 (epitaxial) and 6609 make a fine output pair.

Use three pair for 300W/4R.
__________________
Candidates for the Darwin Award should not read this author.
  Reply With Quote
Old 30th April 2008, 08:36 AM   #4
Vivek is offline Vivek  India
diyAudio Member
 
Join Date: Nov 2000
Location: Bangalore, India
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
__________________
Thank God for DIY audio.
  Reply With Quote
Old 30th April 2008, 08:50 AM   #5
Nordic is offline Nordic  South Africa
diyAudio Member
 
Nordic's Avatar
 
Join Date: Sep 2005
Quote:
Originally posted by Vivek
... I understand the sound quality changes in the PA300 with changes in the output transistor....

Probably no more than swapping sets of speakers
  Reply With Quote
Old 30th April 2008, 09:35 AM   #6
diyAudio Member
 
Join Date: Sep 2007
Send a message via Yahoo to linuxguru
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.
  Reply With Quote
Old 30th April 2008, 10:48 AM   #7
djk is offline djk
diyAudio Member
 
djk's Avatar
 
Join Date: Feb 2001
Location: USA
" 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).
__________________
Candidates for the Darwin Award should not read this author.
  Reply With Quote
Old 30th April 2008, 11:29 AM   #8
AndrewT is online now AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Quote:
Originally posted by djk
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.
How do we tell them apart?

A real 3773 is a great transistor.
__________________
regards Andrew T.
  Reply With Quote
Old 30th April 2008, 04:59 PM   #9
Vivek is offline Vivek  India
diyAudio Member
 
Join Date: Nov 2000
Location: Bangalore, India
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
__________________
Thank God for DIY audio.
  Reply With Quote
Old 1st May 2008, 06:16 PM   #10
Vivek is offline Vivek  India
diyAudio Member
 
Join Date: Nov 2000
Location: Bangalore, India
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.
Attached Images
File Type: jpg img_1802.jpg (83.5 KB, 408 views)
__________________
Thank God for DIY audio.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
CDM2/10 Behaving Badly Dave S Digital Source 71 26th May 2010 10:52 AM
Schematic needed badly Original Burnedfingers Solid State 0 31st October 2006 12:58 AM
DC Servos - Why Are They Badly Regarded ? mrfeedback Solid State 97 27th April 2004 03:16 PM
need help badly natz gangoso Solid State 4 23rd April 2004 06:52 AM


New To Site? Need Help?

All times are GMT. The time now is 09:51 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2