I've already seen project 20kW. I've even printed the schematic and was planning to base my amp on that one, but I decided I didn't need something that could do 5kW per channel, I'm after 4x1800W. Thanks anyway though. As far as an output transformer goes, it would be a good idea, but too heavy and expensive. This is no tube amp, so It's not absolutely necessary.
Fresh-T, are you sure that the Leach Superamp can handle my 150V supply? Are you sure I should try to push 900W out of it as is? It calls for 93V for 300W. It does have enough power transistors to do 900W, barely, but never said anything about such high supply voltage.
I could build 8 of those amps, then put 2 in parallel for each of the 4 1800W sections that I need. How does that sound?
[Edited by Kilowatt on 11-22-2001 at 01:30 PM]
Fresh-T, are you sure that the Leach Superamp can handle my 150V supply? Are you sure I should try to push 900W out of it as is? It calls for 93V for 300W. It does have enough power transistors to do 900W, barely, but never said anything about such high supply voltage.
I could build 8 of those amps, then put 2 in parallel for each of the 4 1800W sections that I need. How does that sound?
[Edited by Kilowatt on 11-22-2001 at 01:30 PM]
output transformer
I am not mentioning a tube output transformer, just a transformer which is used for 100 volt systems or even a plain ac transformer, the distortion introduced can eventually be decreased by proper feedback.Try just to hook up a transformer on a signal generator to see how it will perform.Your 7200 Watts asks for a different solution, and a transformer will not cost more then the rest.
Even the transformer will keep you safe, and a mains feeded
amplifier not...
I am not mentioning a tube output transformer, just a transformer which is used for 100 volt systems or even a plain ac transformer, the distortion introduced can eventually be decreased by proper feedback.Try just to hook up a transformer on a signal generator to see how it will perform.Your 7200 Watts asks for a different solution, and a transformer will not cost more then the rest.
Even the transformer will keep you safe, and a mains feeded
amplifier not...
A fuse or relay protection circuit would probably save the speakers in an overload or other failure scenerio. If the output transistors were shorted and the fuse blew or the relay opened, that would also keep the dangerous supply voltage away from the speaker terminals. An output transformer would not make the output safer under normal operating conditions unless it was a step down for lower impedance. The output signal voltage from this amp will always be something to be treated with respect no matter what (unless I decide to go with lower impedance, which is unlikely).
Just use a lower voltage
Hello Kilowatt,
For the 3.6 KW project, if you want less then 5 Kilowatt, just reduce the powersupply voltage, or go to the webpages
of QSC, they have plenty of schematics regarding power amplifiers.
Or try this link as well:
http://www.epanorama.net
Look under circuits to build.
May I give you a clue? There will be no ready made schematics for your wishes, so you have to adjust it to your own
good, also for the Leach amp.
[Edited by HaaiFaai on 11-22-2001 at 01:58 PM]
Hello Kilowatt,
For the 3.6 KW project, if you want less then 5 Kilowatt, just reduce the powersupply voltage, or go to the webpages
of QSC, they have plenty of schematics regarding power amplifiers.
Or try this link as well:
http://www.epanorama.net
Look under circuits to build.
May I give you a clue? There will be no ready made schematics for your wishes, so you have to adjust it to your own
good, also for the Leach amp.
[Edited by HaaiFaai on 11-22-2001 at 01:58 PM]
output transformer, the sequel
Hello Kilowatt,
It's not about the danger voltage, it's about touching one of the speaker cables, or when a cable is damaged.If you know about mains powered appliances then you know that touching one of the wires will be lethal, so thats why there is a transformer in between, any circuit breaker will NOT prevent you or others from danger.
You know that the earth is connected in the power house with the neutral line?
Hello Kilowatt,
It's not about the danger voltage, it's about touching one of the speaker cables, or when a cable is damaged.If you know about mains powered appliances then you know that touching one of the wires will be lethal, so thats why there is a transformer in between, any circuit breaker will NOT prevent you or others from danger.
You know that the earth is connected in the power house with the neutral line?
Yes, HaaiFaai, I know that, and it's a very good point now that I think about it. Since in a direct line powered circuit, earth is neutral, there could be a safety issue with damaged cables and people coming in contact with speaker hookups. This is especially true with my bridged outputs, because both speaker wires will be live.
However, it would be no more dangerous than a 240V power cord. If the wires are heavily insulated and proper safety precautions are taken, it shouldn't be much of a problem for my purposes. I admit that it may need a transformer for safety if it were used in rainy conditions or in other conditions where there would be more of a hazard.
However, it would be no more dangerous than a 240V power cord. If the wires are heavily insulated and proper safety precautions are taken, it shouldn't be much of a problem for my purposes. I admit that it may need a transformer for safety if it were used in rainy conditions or in other conditions where there would be more of a hazard.
what about safety of your input channel?
Ok, but you need something like a signal transformer at the input of the amplifier, or some form of separation between the mains powered amplifier and the source(cd player/pre amp,etc).(Forgot to mention that earlier)
Ok, but you need something like a signal transformer at the input of the amplifier, or some form of separation between the mains powered amplifier and the source(cd player/pre amp,etc).(Forgot to mention that earlier)
Kilowatt, you probably realise that an output transformer would be very large, expensive and heavy.
If I come across a suitable circuit I'll post it. I haven't forgotten your request and will certainly keep an eye on this thread.
Also, you can't rely on fuses or circuit breakers to protect your speakers unless they are conservatively rated. If they are conservatively rated you will be limiting your output. Use a DC monitor with power up and power down protection, your speakers will thank you.
Regards WALKER
[Edited by walker on 11-22-2001 at 06:39 PM]
If I come across a suitable circuit I'll post it. I haven't forgotten your request and will certainly keep an eye on this thread.
Also, you can't rely on fuses or circuit breakers to protect your speakers unless they are conservatively rated. If they are conservatively rated you will be limiting your output. Use a DC monitor with power up and power down protection, your speakers will thank you.
Regards WALKER
[Edited by walker on 11-22-2001 at 06:39 PM]
Yeah, it would, Walker, and I bet you know by now that because of that I want to avoid using one. Actually , I'd need two.
A DC monitor would be helpfull, I cringe to think of the kind of DC thump you might get when powering up or down a thing like this and what it might do to my speakers.
What does everyone think about the Leach amp that Fresh-T recommended? I have some doubts about wether it should be used with my supply voltage or pushed to 900W as it is now. The highest output it talks about in the article on it is 300W into 8 ohms with +/-93V. The power transistors should handle 900W though. If I put two of those in prallel to give me my 1800W into 6 ohms, it would use the same output banks I proposed earlier, but that's cutting it pretty close for those transistors.
[Edited by Kilowatt on 11-22-2001 at 11:01 PM]
A DC monitor would be helpfull, I cringe to think of the kind of DC thump you might get when powering up or down a thing like this and what it might do to my speakers.
What does everyone think about the Leach amp that Fresh-T recommended? I have some doubts about wether it should be used with my supply voltage or pushed to 900W as it is now. The highest output it talks about in the article on it is 300W into 8 ohms with +/-93V. The power transistors should handle 900W though. If I put two of those in prallel to give me my 1800W into 6 ohms, it would use the same output banks I proposed earlier, but that's cutting it pretty close for those transistors.
[Edited by Kilowatt on 11-22-2001 at 11:01 PM]
Leach Superamp:
It uses 8 output trans(4*MJ15003 + 4*MJ15004). If u wanna use it for 900 watt, u must use 16-32. If u want 1800 watt u need 32-64. Also if u use +/- 150 volt, u can use MJ15024+MJ15025 (I use 16+16 of these in my 2000 watt A/B amp and works fine. But they are 16 i parallell, not 8 in parallell and 2 in series. I used 2 years making it and ca $2000-2500 in parts)
MJ15024/5 : 250 volt / 16 amp
MJ15003/4 : 140 volt / 20 amp
MJ15030/31: 150 volt (Drivers, these will be working on their limits)
Also check all smallsignal trans and el.caps if they can handle the voltage. If not they can easy be substituted.
PS: I don't recomend building a 1800 watt amp. Beleve me, it WILL blow a couple of times before u make it stable. And that WILL be very expensive. It will also take a DAY to replace the outputs. ALSO: The larger the amp, the bigger chanse of oscillasion (unstable).
It uses 8 output trans(4*MJ15003 + 4*MJ15004). If u wanna use it for 900 watt, u must use 16-32. If u want 1800 watt u need 32-64. Also if u use +/- 150 volt, u can use MJ15024+MJ15025 (I use 16+16 of these in my 2000 watt A/B amp and works fine. But they are 16 i parallell, not 8 in parallell and 2 in series. I used 2 years making it and ca $2000-2500 in parts)
MJ15024/5 : 250 volt / 16 amp
MJ15003/4 : 140 volt / 20 amp
MJ15030/31: 150 volt (Drivers, these will be working on their limits)
Also check all smallsignal trans and el.caps if they can handle the voltage. If not they can easy be substituted.
PS: I don't recomend building a 1800 watt amp. Beleve me, it WILL blow a couple of times before u make it stable. And that WILL be very expensive. It will also take a DAY to replace the outputs. ALSO: The larger the amp, the bigger chanse of oscillasion (unstable).
Yeah, that all seems about right. Actually, 16 outputs (MJ15004+MJ15004) is almost pushing the limits of the transistors, it should hold though. How would it work if I built two 900W Leach amps and put them in parallel, with connections between them only at the input, output, and power hookups, to make one 1800W amp. I would then use 4 of those as I had planned with two bridged per channel. Would that have less oscillation problems than a single 1800W Leach amp?
If I put two 900W amps in parallel for 1800W into 6 ohms, would that be more stable than one 1800W into 6 ohm amp?
Kilowatt,
If you put 2 x 900W amps in parrellel then they will drive 12ohms each which is double the actual load so each supplies the full voltage swing of the 1800W amp but 1/2 the current ........ you are probably more likely to get a 900W more stable quicker (ie. blowing it up fewer times) but the output stages of the 2 amps will have to be extremely well matched to ensure that they share the load equally. Also, because each amp is supplying less current (half) the distortion will be quite a bit less.
[Edited by AudioFreak on 11-26-2001 at 05:45 PM]
If you put 2 x 900W amps in parrellel then they will drive 12ohms each which is double the actual load so each supplies the full voltage swing of the 1800W amp but 1/2 the current ........ you are probably more likely to get a 900W more stable quicker (ie. blowing it up fewer times) but the output stages of the 2 amps will have to be extremely well matched to ensure that they share the load equally. Also, because each amp is supplying less current (half) the distortion will be quite a bit less.
[Edited by AudioFreak on 11-26-2001 at 05:45 PM]
i can't see any 3 KW speakers on the market, and i can't forsee any being manafactured in the near future, such a beast will be impractical using the traditional speaker design. So there is NO point building a HUGE amp
If you built a few 1kw amp like ( http://www.vision.net.au/~anthony/1kwamp.htm ) then the cost of the extra parts for 6 more driver stage (fairly basic) wll be tiny compared to the cost of the rest of the amp. If you want, you could build 8 of these and have 4 bridged pairs for either two twin bass units or the beginnings of a surround sound AV setup (scary). That would be a amp to talk about!
True, the no transformer idea sounds nice, however the practical implications of it deem it for theory only (if you have read up on your electronics practice you should know why by now).
The setup that neson pass was talking about was only at around 170V (half of your proposed amp) and that was mono railed i think.
If you built a few 1kw amp like ( http://www.vision.net.au/~anthony/1kwamp.htm ) then the cost of the extra parts for 6 more driver stage (fairly basic) wll be tiny compared to the cost of the rest of the amp. If you want, you could build 8 of these and have 4 bridged pairs for either two twin bass units or the beginnings of a surround sound AV setup (scary). That would be a amp to talk about!
True, the no transformer idea sounds nice, however the practical implications of it deem it for theory only (if you have read up on your electronics practice you should know why by now).
The setup that neson pass was talking about was only at around 170V (half of your proposed amp) and that was mono railed i think.
i beg your pardon, it was 170 +/-, how did Mr Pass balance out the mains then? or whas it using both sides?
Maybe you just include a pair of rubber shoes/gloves with every amp 😉
God thing you get a spur fitted it, my house has fairly standard mains wiring (not good, but not shoody either) however the lights still dim with 'thumps' and thats only a couple of Kwatts. At this level, the neighbours get up tight anyway, so it's only for 'testing' (i.e when friends are around!)
Maybe you just include a pair of rubber shoes/gloves with every amp 😉
God thing you get a spur fitted it, my house has fairly standard mains wiring (not good, but not shoody either) however the lights still dim with 'thumps' and thats only a couple of Kwatts. At this level, the neighbours get up tight anyway, so it's only for 'testing' (i.e when friends are around!)
No, it would not be more stable. When parallelling 2 (or more) amps, some sort of power resistor in series with the output of each amp will be required for equal current sharing. It's better to just doubble the outputs for the one amp, and get your 1800W@6ohm. But I don't recomend buiding one amp this large.
If u absolutly need 1 amp of 1800W, build 2 900W@12ohm, make sure they each works perfectly, then invert one's input, and bridge them. Then you get 1800W@24ohm!!!! (220 Volts RMS at the output!!) then you must series 2 of your 12ohm subs, and get 900W/sub. I don't recomend this because 220 VOLTS at the output!!!
But the easiest way is to use 8 amps (900W@12ohm) for 8 subs (900W/sub)...
If u absolutly need 1 amp of 1800W, build 2 900W@12ohm, make sure they each works perfectly, then invert one's input, and bridge them. Then you get 1800W@24ohm!!!! (220 Volts RMS at the output!!) then you must series 2 of your 12ohm subs, and get 900W/sub. I don't recomend this because 220 VOLTS at the output!!!
But the easiest way is to use 8 amps (900W@12ohm) for 8 subs (900W/sub)...
Fresh-T,
Will the leach superamp board that one can get from the M. Leach website be able to handle the current of a 3 ohm or 2 ohm continous load if enough output transistors were used? Would I have to modify any of the traces on the borad? And would 1500 VA be enough for the 2 ohm load?
Thank you,
Opie
Will the leach superamp board that one can get from the M. Leach website be able to handle the current of a 3 ohm or 2 ohm continous load if enough output transistors were used? Would I have to modify any of the traces on the borad? And would 1500 VA be enough for the 2 ohm load?
Thank you,
Opie
Yes. You didn't specify your voltage rating on your trafo. Assuming 2*55 volts (no load), the DC rail is 76.6 volts (no load). You will probably get (ca (55*0.8)¨2 / 2) = 1000watts@2ohm. You will need 1500-2000 VA trafo. But you must at least double the output trans (16-32).
Just incase you can put solder on the traces from rail to the drivers (Q26,Q16,Q17,Q27), between them, and to the outputs.
Use a total of 100.000uF of capasitance (0.5*0.1*76.6¨2) = 300 Joules.
(all this for 1 channel off course)...
Just incase you can put solder on the traces from rail to the drivers (Q26,Q16,Q17,Q27), between them, and to the outputs.
Use a total of 100.000uF of capasitance (0.5*0.1*76.6¨2) = 300 Joules.
(all this for 1 channel off course)...
Hi FRESH-T
Extra solder on copper traces doesn't improve the current handling capability of a PCB trace. The impedance of solder is so much higher than copper that the most of the current is still going to flow through the copper no matter how much solder you put on the trace. If you are worried about excessive current flow in a trace then either use PCB's with heavier copper (4 oz), make the traces wider and shorter, or do both.
Phil Ouellette
Extra solder on copper traces doesn't improve the current handling capability of a PCB trace. The impedance of solder is so much higher than copper that the most of the current is still going to flow through the copper no matter how much solder you put on the trace. If you are worried about excessive current flow in a trace then either use PCB's with heavier copper (4 oz), make the traces wider and shorter, or do both.
Phil Ouellette
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