Trying to squeeze at least 200 watts each from a pair P3As but Rod says don't go over 35v bridged. I have a transformer rated at 30v/3a, so 42v, right? What is the risk, heat? Or, will they just explode?
My other option is a transformer rated at 15v/7.5a, what output would this produce?
My other option is a transformer rated at 15v/7.5a, what output would this produce?
What load will you be running the amp into?
200W into 8ohms bridged requires rails of about +/-32V
200W into 8ohms bridged requires rails of about +/-32V
It'll depend on which output transistors you used.
The OnSemi MJ(L)2119x are very rugged, and should be able to give you that output with little (if any) difficulty. Ditto to the MJ15003/4 (TO-3)
The recommended (by Rod) Toshiba transistors are usually a little less forgiving of being overdriven, but still should be okay at that load. Of course, if you used 2n3055/MJ2955 as your output pairs, all bets are off. 🙂
The OnSemi MJ(L)2119x are very rugged, and should be able to give you that output with little (if any) difficulty. Ditto to the MJ15003/4 (TO-3)
The recommended (by Rod) Toshiba transistors are usually a little less forgiving of being overdriven, but still should be okay at that load. Of course, if you used 2n3055/MJ2955 as your output pairs, all bets are off. 🙂
Thats just what I was hoping to hear, I am using the Toshibas but may change them out.. what about NTE 2328/29?
i recommend the OnSemi MJ(L)2119x for bridge application. the 2SC series and the NTE2328/29 wont be able to handle such output at 42V rails
+/- 42 volts
I bought a Marchand kit from Quality Kits in Canada using an old RCA design modified by Williamson (blameless Class B?) for the sub on my system. It uses two pair of 3055/2955 for output transitors and is rated at a maximum voltage of +/- 50 volts. Is it going to blow up with the expensive 30-0-30 toroid based power supply I am building? Thanks.
I bought a Marchand kit from Quality Kits in Canada using an old RCA design modified by Williamson (blameless Class B?) for the sub on my system. It uses two pair of 3055/2955 for output transitors and is rated at a maximum voltage of +/- 50 volts. Is it going to blow up with the expensive 30-0-30 toroid based power supply I am building? Thanks.
From my experience using Mj2955/2N3055 at +/- 50 V is not a good thing.Even using an 8 ohm load it is unreliable,it may work for a while but overdriving it even momentarily will surely blow it.It is better to use the new Toshiba pair 2SC5200/2SA1943 it is very cheap and durable.I have tested this even on +/- 75 volt even with a load of 4 ohms using only 2 pairs(for testing only) and it worked fine.
MGR
MGR
No doubt it will work, but for how long remains to be seen. The 2955/3055 pair doesn't have very good SOA at all at 50V, and much better transistors can be had for minimal amounts of extra money.
Seeing as you're dealing with TO-3 transistors already, why not replace the output pairs with MJ21193/4 or MJ15003/4 pairs?
If you look around, you can get them relatively cheap. I know I've seen them sold for about $2usd each before.
If you can't find them, let me know and I may be able to help you source them or sell you some extras if you're in Canada (I'm in Vancouver)
Seeing as the extra output pairs will cost you only $20 at most and will be drop-in replacements for the old ones, I don't see why you wouldn't grab them. 🙂
With either of the recommended output transistors, the output stage should be damn near bulletproof. The 2SC5200/2SA1493 mentioned are quite durable as well, but only come in plastic flatpacks and will require redesign of the mounting on the heatsink. The OnSemi/Motorola ones I recommended above just drop right in.
- Status
- Not open for further replies.