| danielkelley10 |
As per the title, im looking at building a powerfull class d amp, tbh i really dont have a clue where to start, i have built amp circuits in the past from kits etc but as far as design goes im clueless :(
Basically im looking at making a amp which can produce 5000 watts or so at 1 ohm. So the outpud needs to be somewhere in the region of 75V and capable of switching 75Amps :bigeyes:
The usable frequency bust be between 10Hz and 80Hz
The amp does not need to be good quality just efficient and very powerfull, Does anyone have or can anyone draw up a schematic for a basic circuit that will do the job? It does not need any bells and whistles like protection etc, im just after pure power.
Many thanks in anticipation |
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| richie00boy |
Designing (or even building from a schematic) something with that kind of power at that kind of impedance is not for the faint hearted. Throw in the added problem of a switching PSU to cope and you may as well forget it.
I'm guessing a little from your sig here as to what your intentions are. If you are adding another (pair of?) speaker to achieve your desired SPL, just add another amp for it. Paralleling speakers on one amp is just a foolish way to do things, IMO. You give yourself massive current transport problems and actually lower your achieveable output because of huge losses.
If you really must use one amp, and you want to build your own, you would be far better off making an amp that puts out high *voltage* rather than current, and connecting drivers in *series* to gain *higher impedance*. This results in much less current demands, making everything easier and less lossy. |
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| danielkelley10 |
| ok, so how about a 4 ohm load then? i know its a big ask if its not possible i guess i will have to do it the old fashioned way :( i was looking for a challenge to pass my time over the winter. I wouldnt be able to use the amp for competitions as it would not be commercially available, i just wanted a little play :) But yes it would be nice to push the 150dB barrier :D |
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| IVX |
hi,
Probably 5k@1ohm class D sub amp with enough sound quality for SPL is quite simple task vs SMPS for it. About 500A@12V!! As far as i know, for 150db sufficiently two 12" subwoofers and 1 up to 2Kw.:bomb: |
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| ghemink |
| quote: | Originally posted by danielkelley10
ok, so how about a 4 ohm load then? i know its a big ask if its not possible i guess i will have to do it the old fashioned way :( i was looking for a challenge to pass my time over the winter. I wouldnt be able to use the amp for competitions as it would not be commercially available, i just wanted a little play :) But yes it would be nice to push the 150dB barrier :D |
I guess with 150dB you blow out the windows and roof, but probably those are already heavily reinforced.
Have fun, this stuff is not my cup of tea. If I would have to do it, I would like the other replyer use more amps.
Gertjan |
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| danielkelley10 |
my current amp pulls around 350 amps at full power, producing around 3000 watts. it will only be run for very short perids of time, i can sustain 12V with 1200amp draw for upto about 10 seconds. It will only need to operate for about 3 secconds so this shouldnt cause a problem.
Do you think it would be easyer to modify my current amp to do the 5000 watts or start from scratch? As said SQ is not a issue it will only be used to play a 54Hz sinewave (or there abouts) not for listening to music.
Is there somewhere i could get a schematic? I know i can get schematics for other 3000 watt amps but they have loads of computerdriven protection/logging systems built into them which i do not need. If i got a copy of them would anyone here be able to loose all the non applicable junk and modify to do 5KW? |
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| danielkelley10 |
| ohh the reason i would like 5kw from one amp is i would like to use 2 of them to put 10KW through my sub. (yes i know i am a looney, but i also knowthe sub will take it for 3 seccond burps) |
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| richie00boy |
I think you are on the wrong track. Your sub voicecoil may be able to take the 3 second burp, but often overlooked is the excursion capability of the speaker. To go up 3dB you need to double excursion. I'm confident you will break your speaker(s) if you try it, as you must already be pushing some massive excursion.
As for modding an amp, it's possible. But the gains would probably be negligible. You would need to rewind the power supply transformer to give out higher voltage. The problem with this is the core is probably already not far off saturation (if not already), so the supply would just collapse to the same level as before anyway.
I'm assuming you are already running at 1 ohm. If you are not, you could try this for 3 sec burps, at no cost except an amp that will not last very long and may well break after a few goes. As said above though, I'm confident this is not worth trying due to the speaker excursion being the limiting factor. Even if you could somehow measure excursion and keep to a limit, it would probably only get you 0.5 dB tops. |
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| danielkelley10 |
Excursion at the tuning frequency is pritty low as the box it stned to 51Hz to peak at 54Hz, due to playing at the tuning frequency the excursion is minimal. i know the sub can handle 10Kw people have run 12 KW into one of these.
Im currently running a 0.75ohm load, but due to impedance rise due to the box the amp is actually seeing a 2ohm load so it is running the full 3000 watts possible.
Could i not use bigger cores then rewind accordingly? I know these amps can be run off a 18 volt supply for competitions (making them produce in excess of 4000 watts) so would i be able to rewind the power supply torroid to give the amp the impression it is receiving a 18 volt feed? |
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| richie00boy |
How many speakers are you running?
It depends on how the amp PSU works whether you will actually get any increased output with rewound secondary or primary, or more input voltage. If the design is such that the amp rails are regulated (fixed) then you are wasting your time. If there is no regulation/feedback taking place then you have room to experiment. I would have thought that a high end amp would use regulation. But maybe SPL competition amps don't have this. Yuk.
However, without specialist equipment, knowledge and experience you are limited really to just upping the secondary voltage. If you start messing with the primary the chances are you will run the core into saturation and fry the switching devices. It's too fine a balance between working and fire at those kind of power levels. |
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| danielkelley10 |
Im just running a single 15" DVC sub (dual 1.5ohm coils)
its definatly not a regulated amp, i may well have a play and see what i can do. If not i guess i will have to invest in another amp or 2, and get sub reconed to dual 1ohm coils. |
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| kilowattski |
| Why do you list USA amps as your homepage? Are you affiliated with them? Something is fishy here. |
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| DigitalJunkie |
Why not use more a efficent speaker/enclosure to make better use of the power you already have?
5KW is alotta juice.. Don't forget about the 2-3 extra alternators to power it.. :hot: |
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| HFGuy |
How about this ?
If you want to break the 150dB SPL barrier try this. Forget about amps, even class D isnt that effecient when you add a switching power supply, and has limited current supply. So assuming you only want to beat the 150dB mark with a test tone you can use a power inverter
Start with a DC-DC converter followed by a IGBT microcontrolled power inverter. The output will be nasty as hell ( closer to square wave then a sine wave, but you'll only get the fundamental harmonic ) This is how large AC-motors are driven. You can vary the frequency by adjusting the output gate signals for the IGBTs.
P.S. DONT KILL YOURSELF IN THE PROCESS |
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| tiki |
What about this insane idea?
The bridge circuit uses the resonant frequency of the 100µH/100000µF LC-series. It has to be tuned carefully therefore.
But you need much more appropriate Mosfets to handle the 4000Apk AC current. :bigeyes:
The current is flowing through the inductor and the caps too. Calculate for the maximum ripple current of the caps (you would need ~100 Sikorel caps instead of 10 in the simulation, don't cook them).
Good luck, Timo |
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| danielkelley10 |
sounds interesting tiki,
and kilowattski, the reason my homepage is set as USAMPS is:
1) because i like their amps(although they are out of my price range) i have borrowed a couple from the guy who is a friend of mine and the UK importer of them.
2) They are great amps and are rock solid, ive never seen one break unlike SPL Dynamics amps which i see go pop regularly.
3) and finally i dont have my own homepage so thought i would just put a good link in there. |
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| danielkelley10 |
| ohh i wish i was affiliated with them then i could probably afford to run their kit rather than finding ways to maake the best use from the limited kit i have. |
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| Brian Donaldson |
| Bypass the amp all together. Buy a 7000 watt gasoline generator and hook the 220V output straight to the woofers. You can adjust the govener to get the frequency you need (40 hz to 70 hz):smash: |
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| danielkelley10 |
| thats a good idea, i hadnt thought of that, i know the sub i use can cope with being wired directly into a mains socket, thanks :) |
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| ewildgoose |
| Well, the Zappulse modules can get about halfway to your rated power in bridge mode. Using more drivers AND more amps (seperately) would give you an extra 3dB output and also move the amp into a more reasonable current range. |
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| dmfraser |
| See the automotive section of www.schematicsforfree.mattsoft.net. You will find a schamatic for a Kicker brand amp that delivers 1000W to the LF. Build that for practice first. Then, from what you learned from that, tackle the 5000W amp. |
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| dmfraser |
| Yes, connect the sub directly to the 50 or 60 Hz output of a generator, through a triac. Then extract the bass line from the music with a bass beat extractor like on www.schematicsforfree.mattsoft.net in the lighting section send the output to the triac set to switch on at zero crossing, pulse the AC at the beat rate of the music. |
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| elviukai |
hi all there,
I sugest the other solution. build your own drivers with x max 1 to 2 mm102-108db/w/m or 109-112db/w/0.5m , make sure that magnet is from bla bla bla another planet with really strong magnetic field :devilr: (like lowthers do)
conect in paralel 10 of them ant do some nice input by vdo dayton cdp. I quest 10 to 15 wats will be enought to reach 150db spl :cannotbe:
luck in your mad projects ;) |
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| danielkelley10 |
| thanks for the suggestions, im trying to keep all the install in the boot, but those schematics look very interesting, thanks :) |
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| tiki |
The way with less amp power needed could be a resonating impedance transformer (p converted to v) -> (folded) horn, transmissionline e.t.c.
Check, if you can do this first. The settling time is long enough to allow a high Q for a high sensivity/efficiency. But you would need specialised drivers of course. And: the bigger the radiating area, the better is the directivity (-> beaming, have a look into PA-forums).
tiki |
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| peranders |
| Mr Kelley, 5000 watts in your car, is it for music or some test signals? 150 dB, are you in the car when you have 150 dB's? |
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| danielkelley10 |
150dB is with sine waves, realistically music it will play around 145dB. any yes i do sometimes listen to it pritty loud from in the car but not when playing a test tone as i would still like to have some of my hearing later on in life :)
Transmission line would be good however space is a issue, i need to keep the system in the boot and so only have about 6^ft to play with. the trunk is aproximatly 42"long by 16" high x 21"deep. - displacement of wood/sub atc i cant see this being a viable option. i do not wish to change the 15" sub either. |
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| 1audio |
You can add the output of a string of amp in series if you connect them with output transformers. Take a reasonable size amp that you can buy (1 KW for instance) and the total you are after- 5 KW. You will need 5 amps. Each will be driving 1/5 of the total load. Added in series then each amp will be driving 2/5 or .4 Ohm. Use matching transformers, AC power transformers in this case, scaling them for the V in to V out ratio appropriate to this task and connect the secondaries in series. Doing this in parallel increases the chance of amp destruction. Not done normally because good transformers are heavy and expensive.
You still won't get there because the voice coil of the driver will heat up enough to reduce your output appreciably during your test. And this is assuming that the magnet won't get demagnitized during the test. Both are real phenomena and will make the problem much harder to overcome than just adding more watts. The technical term is power compression. You could use Helium cooling, it may work. Its used in cutterheads for phonograph records.
-Demian |
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| lumanauw |
I have a close friend here that just break 172dB with 2x12" subs. He uses 1 power amp.
I often visit his place and follow his rising records. When he hits 145dB, it is on ordinary car. When he breaks 150dB, he uses 8x15" subs with 16 classD power amp.There are stiffing wood bars everywhere in the car. When he hits 170db, he uses 2x12"sub with 4 power amp. The car maybe add another 700kg weight from treatment. Now he does 172dB with 2x12" sub and 1 power amp--> now you couldnt drive the car. You have to pull out 50% of the setting to be able to drive the car. When he arrived the SPL arena, he puts back the 50% back.
Power rating and subwoofer number has minimal effect in building competition SPL car. The most important is treating the car as a bandpass box. Measuring the volume for front box and rear box, while you are sitting on one of the box. The mike position is also very important to know. In his car, you shift the mike 50cm, the SPL is only 150dB, but in the exact position (passanger's seat with 50cm mike holder you get 172dB).
So, you will have to put 1/2" thick resin everywhere in the car room, stiffen the roof and lower deck with 1" MDF, make another front glass with 1/2" glass, stiffen the doors with resin and put tons of asphalt sound damper inside the car.
Any system more than 145dB is dangerous for yourself, especially for hearing. That SPL friend of mine just dare to stay for 3seconds inside 155dB car. I try 155dB with him for 3 seconds. It's feels like your hart and brain is just empty room. Couldn't think of anything and walk straight after hearing 155dB SPLcar. Takes 3 minute to recover after 3 second shake.
More than 155dB, hmm..... I think no one will try it inside the car, even the world SPL champion. |
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| danielkelley10 |
your friend obviously has a walled SPL car,i compete in the street classes so everything must fit in the trunk. The pressure sensors we use are the termlab, your friend uses the audio control mic from your description. term lab is much more linier than the ac mic as it is based on a pressure transducer rather than a microphone, this makes it much more accurate at higher levels. the 148.6 i currently hiting my car is 152.x on the ac mic as far as i can remember. i have sat in a car of 155+dB at 40Hz on the termlab sensor so i would guess 158-160dB on the audio control mic and yes i can confirm this is scarily loud. This was in a car tuned to 18Hz for street bass, i would hate to think how loud it would have been if it was tuned to 70-80Hz like mose walled spl cars.
As said i cannot wall my car because of the class i compete in, infact i couldnt use the planned amp in competition either, but i just wanted to see if i could do it for my own benefit.
I have modified my box now and think i have managed to gain a dB or so(it sounds louder to me, but havent had time to put it in on the sensor) So i may well be able to make the 150+dB without a new amp :)
If i can the next target will be 155dB :D this is going to need a lot more effort as the world record in my class is 155.2dB although i believe they were running 6KW or so.
The current UK reccord is at 149dB i plan to beat this at my next event :)
My car has no sound deadening at all so if i deaden the car i hope this will gain me a dB or so.
I have been told i can borrow a matched pair of amps off a friend next season which will give me 6-8KW depending on the sub i use.
If anyone has any more suggestions on how i could improve my output, please feel free to reply :) |
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| lumanauw |
| quote: | | My car has no sound deadening at all so if i deaden the car i hope this will gain me a dB or so |
You do some plate stiffening (with resin+fibreglass mat) and sound damping (with asphalt mat) you could improve dB quite alot. Since you are in street class, put those in places like floor, window inner, that not too obvious. But remember, after putting those, your tuning frequency will slide a little. Have to re-tune the tuning frequency after sound damping.
Also look for holes anywhere inside the cabin and try to seal every hole related to outside air. Like cables/AC pipes usually have leakages.
Rigidness of your cabin is the key of gaining high SPL (with the right tuning, offcourse:D ). The good subwoofer is no.2. Power amp rating is no.3. So try to maximize it where ever you can, for limitation in your class. |
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