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1500 Watts RMS - 2 Ohms, to come soon
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Old 21st June 2004, 01:23 AM   #11
millwood is offline millwood  United States
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Originally posted by Eva
These are fast but fragile transistors so prepare to use 6 pairs or so. Another alternative is MJE15030/MJE15031 or MJE15032/15033,

the 4793 is also very very bright. I like 15030 a lot better.
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Old 21st June 2004, 03:01 AM   #12
AKSA is offline AKSA  Australia
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Oops!! Eva is quite right, my mistake, apologies Effendi.....

Substitute the drivers with MJE15030/31 (one per rail should be sufficient) but now the VAS current will need to come up to about 12mA to drive the higher input capacitance of the ONSEMI devices.

You could use the 4793/1837 in the VAS role, actually. They are certainly fast enough, and at 12mA they will be dissipating 1W apiece on 84V rails, so heatsinks are now required on all devices from VASs forward.

Thanks Eva (is this Guido Tent?)


Aspen Amplifiers P/L (Australia)
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Old 21st June 2004, 10:43 AM   #13
carlosfm is offline carlosfm  Portugal
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Originally posted by AKSA
Thanks Eva (is this Guido Tent?)
Anyway, location is secret, but I know that flag.
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Old 21st June 2004, 01:39 PM   #14
Ultima Thule is offline Ultima Thule  Europe
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I don't know what you have at the moment decided for a rail supply voltage but in your first scheme you have +-104 volts and say you are going to use BC556/546 pairs, do you think it's going to "float" or "sink"?

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Old 21st June 2004, 02:02 PM   #15
destroyer X is offline destroyer X  Brazil
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Default Those transistor have lower voltage on them

I will check, but is working, do not explode already!

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Old 27th June 2004, 04:42 AM   #16
Workhorse is offline Workhorse
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Arrow Commentable Thoughts

Originally posted by AKSA
Hi Carlos,

I'd like to look at the current issues raised by Amp_Man. I believe he is right; you need more current amplification.


ThanKs AKSA for clarifying the statement about current amplification to Destroyer X

Carlos , u must insert an extra pre-driver stage to drive ur driver transistors.

With regards
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Old 27th June 2004, 10:25 AM   #17
destroyer X is offline destroyer X  Brazil
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Default This amplifier was measured, weigthed and considered not enough

Supply voltage reduced a lot, can not hold the amplifier, i sent back to Hurricane and said him:

Here is your hot potato! hohohô

Had not motivation to increase it, because it was considered not good sounding amplifier, also with very low power related all his maximum theorical power... in 30 watts comparison test, this amplifier gonne the almost last place related others.

More details in the Van Melter comparison test made.

Voltage, when hard driven, reduced 40 percent as i already said... this way, cannot be so good, and thats the reason nothing explode for a while.

Thanks all informs, i will give all those to hurricane, also i have some better transistors to give him too.

If you like, as an exercise for you, without doubts much better knowledge than mine, can modified it entirelly, because no owner too, this one belongs to mankind, this way, can be Amp man, Eva's or Aksa's amplifier, i am short circuited brain those last 3 days, cannot think in this earthquaker, because too much surprised with DOUGLAS SELF amplifier, that i am simulating those days.... without believe what Multisim are showing me, perfect square wave in 10 hertz, also 100 kilohertz!

This Multisim 2001 never shown me this performance!, no amplifier simulated did that till now!, i had concluded that was Multisim 2001 bug!, All amplifiers i made,modified , or copied and entered to simulation, no one did that.... this way i will make it real.... now trying to have 2N5401 because could not find them... and this one cannot be substituted, because quality goes down.(this explains why not good simulation in Aksa and perfect sounding amplifier in real world)

Also i never had this experience before, always moving transistors models and having the performance almost the same..... this time not!.... cannot put others, tried 11 models in simulation...no one worked there, hard unbalance... had to change a lot to stabilize and equalize rail voltages.

I have a lot to learn, thats the real thing, sorry the heavy Troy Horse, a Greek gift as we say in my country.... only power...no good quality the way it is in schematic, and with a falling down supply voltage.

Thats the reason i could have good simulation results with Aksa too.... and the sound, real world is wonderfull, magnificent, perfect.... and simulation dennies that....because of 2N5401 again.

This thread amplifier is more to young boys make loud guitar music than to hear good and soft music, is more usefull to teenagers surrounding that he is at home. .. i already run away of this one.

Thank you all, there's a Troy Gift, maybe a challenge for some newcomer enginneer, or a good exercise to someone.

Have you already seen, in simulation, perfect square waves in deep bass?.....Douglas Self could make one circuit that shows that perfect square wave in simulation.... those things makes me feel that is better to find another hobby, because 40 years doing amplifiers, and beeing surprised already...without understanding what's is going on!

bye and thanks

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Old 29th June 2004, 02:27 AM   #18
Mr Teal is offline Mr Teal  Canada
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I'm very interested in this project. I just bought these on ebay, so I should have about +/- 90V rails. Hehe... Might want some kind of soft start cct.

I'd love to see a fairly efficient amp capable of 1-2kW as a project, it'd make a great mate for 4-6 tempests.
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Old 29th June 2004, 03:24 AM   #19
Brian Donaldson is offline Brian Donaldson  United States
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Those are sweet transformers. For 9 dollars each!
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Old 29th June 2004, 03:55 AM   #20
destroyer X is offline destroyer X  Brazil
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Default Good Mr. Teal, if something cracks here in my building i will think you made it shake

You made my building shake too much.

The supply used from hurricane, my friend, was bad, when switch on, voltage reduced a lot, this way, no explosion on transistors.

The first stage, will be more safe using 2N5401 or other with better voltage capability.... also the Output, use MJ15025, to replacement of others, read entire thread, many friends helped a lot with adequate replacements of more adequated drivers.

Thanks Eva, also Hugh, and all others that came here to help.

This amplifier needs a very heavy transformer, and do not look at energy bill, i think you will be surprised. hohohô

Regards, and good luck to you........but your neighboors!!!!

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