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Cheap Balanced Power Amplifier - Chip or Class D

glenn jarrett said:
would a transformer be better ?
this wouldn't add any gain unlike the DRV134
does anyone know of a transformer (single in balanced out) that would be good for this application ?
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It's not the gain of the drv134a that's a problem, simply taking it into account when analysing the behaviour.
 
themystical said:
All looking very good!🙂 Just built mine and I am definitely not going to need to go BTL for my headphone amp project. The detail is certainly all there and sounds very accurate and quiet but whether it is a fun listen compared to my valve amp, I am not sure. Will have to do some more listening!🙂
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I have done extensive listening over the last couple of days and I can only revert to some old cliches! I keep hearing stuff that I had never heard before! This is probably the best headphone amp I have ever listened to and I have heard a few?! I don't believe in break-in but I certainly have a different impression now than when I first heard it - it seems to have changed from good to outstanding!:confused:
 
TheDecameron said:
You could end up wearing the voice coils as grommets.
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Could is the operative word here and there is no denying that and if you want to be ultra cautious, 100 Oms in series is usually sufficient attenuation to protect the headphones and the amp. This is common wisdom but not something that I do.
IMO, for high impedance cans, it is usually irrelevant whether you use a dedicated headphone amp or speaker amp. The impedance of the headphones limit the power delivered. For low impedance phones, it is possible for the amp to deliver more power than the voice coils can handle so you have to be careful with the volume control and not overdrive them. There is also the issue of gain and hiss on these, but the icepower module is so quite, it doesn't seem to be an issue. Not tried iems though.
This method is for technically minded diyers and not the general public who need indestructible plug and play.
 
I bought a number of these B&O Ice Power modules to build a pair of small active speakers with. Have to say they are excellent and far exceeded my expectations.

Here's one in a case I knocked up to test with.

SAM_0989%20-%20LowRes_zpsepddwv9w.jpg
 
ok so i get 5.9vac from the standard module @1khz full volume on my phone and preamp and 10vac from the modded module what does this work out to ?
i know this is full power and probably in to distortion but i just want a bold park figure
 
glenn jarrett said:
ok so i get 5.9vac from the standard module @1khz full volume on my phone and preamp and 10vac from the modded module what does this work out to ?
i know this is full power and probably in to distortion but i just want a bold park figure
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Into what impedance/resistance? Your voltages correspond to 4.3 W and 12.5 W into 8 ohm, double that into 4 ohm.
 
sorry its a 4R 200w dummy load the AC voltage was measured across the dummy load playing a 1khz sine from my phone at full phone vol and the preamp on full vol
the module is rated at 47w into 4R ?
i have measured the voltage with 2 meters and both gave same reading
cant understand why i only get a fraction of that ?
any ideas
 
i have just dowloaded one for my pc and thats 820mv out
just turned it on full and getting 34.9vac at this level i can hear the power resistors whining ?
 
To get 47 W into 4 ohm you would need 13.7 V, so 1.6 times what you now get. You would achieve that by increasing input voltage from 180 to 290 mV.
 
the 34.9v was from a hacked module the btl version is 170w @4R i have converted a single ended into a btl version and want to see if i have 170w output
am i right in saying that 34.9vac across a 4R load is 405watts so 170w without any distortion looks possible
 
Julf said:
P = U² / R, so 34.9 V into 4 ohm is 305 W, not 405.
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my bad used a ohms law calc without my glasses on
yep 305w going to connect my scope tomorrow and turn it up until i can see distortion then turn it back and record the result just before it distorts to find out if i have 170w
so 34.9v x 34.9v =1218.01 divided by 4 =304.5025w
 
mark121211 said:
I bought a number of these B&O Ice Power modules to build a pair of small active speakers with. Have to say they are excellent and far exceeded my expectations.

Here's one in a case I knocked up to test with.

SAM_0989%20-%20LowRes_zpsepddwv9w.jpg
Click to expand...

That looks excellent. Have you got a buffer somewhere that I can't see or is that just a passive pot attenuating the line in?
 
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