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Introducing the PowerReg

Is it best to use separate +/- Power regs for each channel of a stereo chipamp or can I split he outputs of a single + & - reg to each powerchip?

Still looking for advice on using these in my amp. Any chance of a response to my earlier post please (post 73)?

Thanks.
 
mikesnowdon said:
Teddy.

Im interested in implementing the PowerReg in my CA 340a SE integrated. Its power amps are based on 1 x LM3886 p/ch and currently run on +/-34v . The trafo is 24-0-24v AC, about 120VA, 10'000uf smoothing caps. Im thinking that the basic config you used on you chipamp will be the best way to go. Can you provide a schematic for wiring or give me any advice on this? I have the 340a SE service manual which I could email to you.

Thanks in advance ;),

Mike.
Click to expand...

Mike,

You can use the same trafo and caps, and set the PowerRegs to 27-28V. Clipping may occur slightly earlier but unless you are using very high volume levels you'll gain big time.

Teddy
 
mikesnowdon said:
Is it best to use separate +/- Power regs for each channel of a stereo chipamp or can I split he outputs of a single + & - reg to each powerchip?

Still looking for advice on using these in my amp. Any chance of a response to my earlier post please (post 73)?

Thanks.
Click to expand...

Better to have a PowerReg for each channel. Less current through the reg yields better regulation (less ripple).

Teddy
 
Cheers Teddy. :)

I have a consideration on the output voltage. According to the LM3886 datasheet (page 14) If I run them on 27/28v I should expect about 40 w/pc into my 8 ohm speakers. Currently the amps get about 34v +/- which gives an apparent power output of *60/65 w/pc (*Interestingly the CA claim 45 w/pc for the 340A SE).

The point is this. Will this small sacrifice in power (if any) have any adverse effect particularly in the bass? Or would the regulated supply actually help the bass despite a littlte drop in power output?

I have 100uf BG STD as local supply decoupling. Would I leave these in place (at the chip) if I use the Powerreg? I notice you used tants on yours, what value did you choose and why did you use tants?

Sorry for all the q's, I,m still learning ;).
 
A powerReg-ed 3875 at 28V sounds much bigger than a non regulated 3875 at 34V (more detailed and natural too), especially at the bass. The only caveat is that if you go real loud you may get clipping.

Better to leave the 100uF near the chip, in most cases it helps.

Don't forget the updates posted along the thread, and also add a 10-20K resistor between the jfet source and the ground (it adds some bias current to the jfet and makes it operate in the more linear region)

Teddy
 
BTW, if your trafo gives 34V on no load, it probably gives no more than 30V on peaks. Design your powerReg accordingly, that is, the output of the 317 should be no more than 29V, and let the voltage divider resistors of the Gyrator drop 2V.

Teddy
 
I am using a 30-0-30 trafo which gives 42v at the chip + & - power pins (1,000uf caps on each rail). Is this likely to cause any problems if the tants on the powerreg are only 35v?
 
The chip takes 45v max. However I am using the LM338 regulated supply as per Decibel Dungeon. Nothing gets even remotely warm.:cool:
 
The problem is that the trafos are 30-0-30. I cannot alter the 1.4 multiplier after rectification. I would have to change the trafo's to say 25v (which I could do, but am lazy!). However having made several Gainclones, I like the sound with the current set up. Maybe I like to live dangerously!
 
35v tants should not be operated at 42v IMO - make sure you are wearing safety goggles at switch on, the buggers explode into really small pieces :)

Richard
 
To be fair, the exploding trick is with reversed polarity, not sure how they act with over voltage (but still doubt they would last long). Maybe try a gyrator cct before the TPR's to drop the voltage down to a sensible level, a PM to Teddy might give you some of his knowledge on the subject.

Richard
 
hi guys
i am new to this forum. i would like to build this to power the lm1875

can someone point me the schematic for the negative side?
just confirmation for negative side component below

T1 = 2N5460
T2 = BC560C??
T3 = D45H11
LR1 = LM337

please correct me if im wrong.

TIA
Erwin
 
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