2 Kw?
Will it the mono-blocks run in bridged mono? Have you thought about how much power you might be able to drive into a 2-ohm sub?
It’s quite a nice amplifier you’ve built there. Light years cosmetically and power wise from the Leach low TIM-3's I helped a friend build for PA use way back when.
BTW, we blew out half our output transistors and a bunch of JBL 2" compression drivers the night before the first gig. I hope you can let yours warm up and proof it in better than we did.
Will it the mono-blocks run in bridged mono? Have you thought about how much power you might be able to drive into a 2-ohm sub?
It’s quite a nice amplifier you’ve built there. Light years cosmetically and power wise from the Leach low TIM-3's I helped a friend build for PA use way back when.
BTW, we blew out half our output transistors and a bunch of JBL 2" compression drivers the night before the first gig. I hope you can let yours warm up and proof it in better than we did.
Thanks for the comments Da5id4Vz, it will be put on test Friday morning for most of the day (it has already been tested but it needs a burn in). The smaller amp can run mono if the larger one fails so I do have abit of a backup.
The amp is current limited to 16Amps so it will not really run into a 2Ohm load, its been tested to 750Watts into 4Ohm so far. I think if I bridged this amp I would destroy my subs in no time.
The amp is current limited to 16Amps so it will not really run into a 2Ohm load, its been tested to 750Watts into 4Ohm so far. I think if I bridged this amp I would destroy my subs in no time.
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Thanks again, I don't have a picture of the finished Tops but this should give you an idea, they are now finished the same as the subs with top-hats and mounting poles:
They contain a motorola compression driver and a Eminence Bata12. Crossed over with the subs at 310Hz. I am setting the whole setup up in the garden on Friday so will post a pic of the entire rig then.
They contain a motorola compression driver and a Eminence Bata12. Crossed over with the subs at 310Hz. I am setting the whole setup up in the garden on Friday so will post a pic of the entire rig then.
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Oops, Think I dated myself again. I dont seem to hear too much talk about this stuff these days.
http://www.gold-line.com/tef/tef.htm
http://www.gold-line.com/tef/tef.htm
matth,
You've mentioned that the amps have been tested to 750watts into 4 ohms.
The original article says that these amps are only capable of 500 watts into 4 ohms (278 watts into 8 ohms) and the output stage cannot run continuously into a 2 ohms load.
How did you manage 750watts? Any mods to the original circuits.
By the way, someone here sent me scanned copies of the original article from the Australian mag, but only upto page 31. Can someone please send the rest of the pages via email. Thanks in advance.
You've mentioned that the amps have been tested to 750watts into 4 ohms.
The original article says that these amps are only capable of 500 watts into 4 ohms (278 watts into 8 ohms) and the output stage cannot run continuously into a 2 ohms load.
How did you manage 750watts? Any mods to the original circuits.
By the way, someone here sent me scanned copies of the original article from the Australian mag, but only upto page 31. Can someone please send the rest of the pages via email. Thanks in advance.
Bricolo said:how was the party?
The disco went well (very loud
) very tired at the end, there were two flights of steps to take all the gear up and down 
.I did take a couple of pics of the setup in situ but the camara is still buried at the bottom of a flight case under the rest of the system (I will attempt to dig it out and post the pics).
Whilst performing the burn in tests on Friday afternoon the main amp went bang with a good puff of smoke
we cut the power and inspected the damaged a decoupling cap on the power rail had exploded. Upon futher inspection I realised my mistake, one cap on both boards was 470uF @ 63v instead of 100uF @ 100v (both identical size!) it was a wonder that either held at all on the 81v rails .I replaced the caps in both boards, rebuilt the amp and away we went with no futher failures. Thank goodness the cap didn't hold out any longer!!
We set the ip to the amp to limit the maximum op to about 300watts into 4Ohms and the tops amp at about 200watts into 4Ohms so running about a kilowatt total, we didn't get it passed about 80% full volume
Anyway the girl enjoyed her 18th.
Samuel Jayaraj said:
It was my understanding that the amp was supposed to put out 500watts into 8Ohms (a little optimistic). In my testing the amp put out about 76v peak at 1KHz (76*0.707=53.7 53.7*53.7/4=721Watts) the amp is current limited at 16amps and the outputs (MJL21193/94) have a SOA of 2.25A @ 80v (14 OPs altogether) 720watts at 53v is 13A approx so is well within the capability of this amp (providing enough heatsinking) with no modifications. The amp will current limit when running into 2Ohms.
Hi Matt
I'm very pleased to hear that the party went well! Did you make any cash, or was this a favour?
Here is a pic of my very modest 'party rig'. I bought the speakers for £140 when Maplin had them on special offer, and the amp (sitting on top) is a two channel bridged LM3886 with limiter, made mostly from junkbox parts. I posed a pic inside it here:
http://www.diyvideo.com/forums/showthread.php?postid=152474#post152474
The sound quality is pretty mediocre, but this system produces more than enough volume for most big living rooms, and has been used for vocal PA outside with good effect. Since the amp has the LM3886 chips directly mounted on a heatsink with forced cooling, and with its limiter, I can leave it unattended without damage.
Nice one,
Tim.
I'm very pleased to hear that the party went well! Did you make any cash, or was this a favour?
Here is a pic of my very modest 'party rig'. I bought the speakers for £140 when Maplin had them on special offer, and the amp (sitting on top) is a two channel bridged LM3886 with limiter, made mostly from junkbox parts. I posed a pic inside it here:
http://www.diyvideo.com/forums/showthread.php?postid=152474#post152474
The sound quality is pretty mediocre, but this system produces more than enough volume for most big living rooms, and has been used for vocal PA outside with good effect. Since the amp has the LM3886 chips directly mounted on a heatsink with forced cooling, and with its limiter, I can leave it unattended without damage.
Nice one,
Tim.
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Cheers Tim,
The gig was a favour, basically my birthday present to her.
I got a nice thank you note a fiver for a pint though
When I started doing favour PA for people all I had was some crap 15" boxs I built with a poxy little horn tweeter and a couple of 100Watt maplin amps. So the kit youv'e got far out does that
If your not to impressed with the quality I can not sell bi-amping enough, my system (to my cloth ears) sounds great to me even at low volume. If you make the XO and a small pair of chip amps to run the tweeters the total return on investment should be great!
I like the amp, very compact. I wish I could make my stuff smaller I don't think my back can take much more .
Time for a GC I think.
The gig was a favour, basically my birthday present to her.
I got a nice thank you note a fiver for a pint though
When I started doing favour PA for people all I had was some crap 15" boxs I built with a poxy little horn tweeter and a couple of 100Watt maplin amps. So the kit youv'e got far out does that
If your not to impressed with the quality I can not sell bi-amping enough, my system (to my cloth ears) sounds great to me even at low volume. If you make the XO and a small pair of chip amps to run the tweeters the total return on investment should be great!
I like the amp, very compact. I wish I could make my stuff smaller I don't think my back can take much more
.Time for a GC I think.
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