posted
Dose anyone still use transformers/accumatch to match the amps to speaker impeadance?
I know that a lot of people drive there amps to extreme clipping, but transformers dont pass DC, so what happens when you drive the amp into clipping, to the output of the transformer?
Are you going to loose massive amounts of power, or just not be able to run the amps clipped? (still a big power loss)
-------------------- - Firestarter - 9 times UK Champion. European Bassrace Champion 2007. IdbL Stock Pro 2 World Record Holder 2006 www.TheFirestarter.net
Posts: 831 | From: England | Registered: May 2000
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posted
The only people that I can think of using impedance matching transformers are for hardcore competition and tube amps(they tend to have them built in). As for clipping, if anyone is driving their speakers to extreme clipping( > 10%), power loss should be your last concern. It's actually a good safety to keep from frying and bottoming the subs. So transformers are good if you're clipping your amps.
Posts: 768 | From: Ottawa, On, Canada | Registered: May 2000
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posted
If we are getting a db or so more by heavily clipping our amps (like square wave output) then I dont want to loose this by the transformer stopping this power by doing funny things with the wave form.
-------------------- - Firestarter - 9 times UK Champion. European Bassrace Champion 2007. IdbL Stock Pro 2 World Record Holder 2006 www.TheFirestarter.net
Posts: 831 | From: England | Registered: May 2000
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posted
If you're using an almost square wave, I don't think a transformer will work for you. The EMF field will collapse with the DC current. Unless using pure sine-waves, I don't thinka transformer will ehlp you. I don't have the numbers on what the power losses would be but I think it would look like transient peaks when the voltage swings.
Posts: 768 | From: Ottawa, On, Canada | Registered: May 2000
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posted
There is not really any reason to use square waves. You want to send the maximum power at your note to the speakers. All clipping is, is the addition of higher frequency harmonics added to your unclipped signal. In fact they are multiples of the frequency you’re playing, and in this case, the duty cycle being even, they are the odd harmonics. So if you play a clipped signal of 50hz, Your amp will add 150Hz, +250hz, + 350Hz..... And each preceding harmonic will have smaller amplitude then the previous one. If you try to pass this through a transformer, You will get all the sine waves out, but depending on the transformers phase properties, they will not necessarily add back up to a square wave. They all have to be in the correct phase to add back up correctly. I have thought of using a transformer to impedance match the subs to the amp. If you designed your system to peak away from tuning and at resonance, You could tear that sub apart. If I was going to enter a contest that limited amp power, that’s what I would do. Put a big high power sub in a small sealed box so that its resonance frequency is your note and really high impedance, then impedance match it to your amp to get your amps maximum current to it. You could make a 100Watt amp sound like a 2000Watt amp.
[ 08-31-2001: Message edited by: mr.dank ]
Posts: 1259 | From: Fullerton. CA ,USA | Registered: Oct 1999
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hmmm??dank im not sure if i understand you all corectly..??well do you have to use a sealed enclosure?..and why the highimpedance..and would a accumatch be used to do this..or some other type of transformer??.see in usac we are limited in power..so.my mind goin crazy here..but could this really work??and what would it really take to do it?? you can even e mail me direct and let me know ...splmagician@aol...
-------------------- Alan Hall Broken Silence CC 2007 usaci mod 1001-2000 champion 163.6 2003 usaci mod151-300 legal record holder 4th 2002 usaci finals mod 0-150 6th 2003 usaci finals mod 151-300 4th 2004 usaci finals prostock 1001-5000 4th 2005 usac finals mod 301-900 Posts: 667 | From: Troy IL | Registered: Apr 2000
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posted
Basically its like this, as the in-box impedance gets higher,the subs become more efficient (with some exceptions) and the power the voice coil dissapates becomes in some cases a few watts. Your amp is limited to the power it can put out directly by its current. ok, im not even sober so i will explain this when I am!Its kinda comlicated to explain everything. But yes you can increase the amount of power your sub recieves by using a transformer. a 4 ohm sealed sub at resonance might have a 80 ohm impedance. a 100 watt amp (max output voltage of about 28v rms) would only be putting out 0.36 watts. amazing you can move that sub like crazy with only that much power. Resonance can act like a powerfull force!
Posts: 1259 | From: Fullerton. CA ,USA | Registered: Oct 1999
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posted
So here's what you can do with a transformer to increase SPL. Say you have a 2000x running a 4-ohm sub at a frequency where the impedance is 25ohms. The power its delivering to the sub is 90 volts / 25 ohms = 3.6Amps. 3.6A * 3.6A * 4ohms(dc resistance of coil) = 52 watts. This is the real power that is capable of doing work not the apparent power which is voltage * current.
Now lets use a transformer.... Ok, you have your playing impedance Zsub, and your amp can handle say 4 ohms (Zamp). Next you need to know how much current your amp can put out. I max = square root of rated power/impedance. Example.... For a 2000x this would be (2000W/4ohms)^1/2 = 22.5A
Now match the transformer to do an impedance match.
(Zsub/Zamp)^1/2 = K
(25/4)^1/2 = 2.5
K is the turn’s ratio of the primary and secondary. K = N1 / N2, N1 is the number of turns in the primary side, N2 the secondary.
The formula for current in the transformer is I amp= K* I sub
I amp = 22.5, K= 2.5. So I sub = 9 amps
The real power your sub will get is 9amps * 9 amps * 4 ohms(dc resistance of coil) = 324W
That is a 7.94 dB gain in power transfer to your subs.
Your amp is putting out its full 22.5Amps, instead of the 3.6Amps before the transformer!
A few notes, in the real world, transformers don’t work perfectly and you may come out 1-2dB? Short of what you calculated. Also, if you try to play music with this set up, kiss your amp good by if it doesn’t have good protection circuitry. And last but not least, Good luck finding a transformer that has the turns ratio and power handling you need. You can’t just go down to radio shack and by them
Posts: 1259 | From: Fullerton. CA ,USA | Registered: Oct 1999
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posted
oh..damn it!!...so if i even went thruogh all the trouble of finding the parts..the most gain i could se would be what about 350w at most?? if so i would think it would be easier to just have the amps modded from the factory i guess
-------------------- Alan Hall Broken Silence CC 2007 usaci mod 1001-2000 champion 163.6 2003 usaci mod151-300 legal record holder 4th 2002 usaci finals mod 0-150 6th 2003 usaci finals mod 151-300 4th 2004 usaci finals prostock 1001-5000 4th 2005 usac finals mod 301-900 Posts: 667 | From: Troy IL | Registered: Apr 2000
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