Cheap Balanced Power Amplifier - Chip or Class D

[themystical]

both modules bridged with B4 buffer preamp built into my stunt case
the stereo module gives about 13.8vac per channel before distortion into a 4R dummy load which is 47w @4R
and the stereo converted BTL module gives 26.1vac which is 170w @4R
this is a boldpark figure just wanted to find out if i had more power from the BTL conversion which i have

Looks brilliant and it works too. Does it sound much different (better even?) to the stereo module? How are you doing the single ended to balanced conversion?

 

[Julf]

How are you doing the single ended to balanced conversion?

Driving a balanced/differential input with a single-ended output is trivial - no special conversion required. The other way can be trickier.

 

[themystical]

Driving a balanced/differential input with a single-ended output is trivial - no special conversion required. The other way can be trickier.

Except in this case where you need to invert the phase of one of the channel inputs to get bridged mono?

 

[Julf]

Except in this case where you need to invert the phase of one of the channel inputs to get bridged mono?

If the inputs are truly balanced/differential, all you need to do is connect one channel in the opposite polarity.

 

[glenn jarrett]

Looks brilliant and it works too. Does it sound much different (better even?) to the stereo module? How are you doing the single ended to balanced conversion?

the small blue pcb is the DRV134 single ended to balanced driver the vero board next to it are +/- 12v regulators reducing the 25v-0-25v aux output from the module
sounds very good indeed

 

[glenn jarrett]

you could also use a transformer to go balanced but they are expensive and limit frequency bandwidth

 

[mark121211]

Looking at your photo, it would seem that for 230v operation the jumper needs to be on the two pins closest to the blue caps. I fired mine up with 250v when the jumper was in the 115v position, and guess what? It doesn't work! With the jumper in the correct position, it still doesn't work, so there isn't a re-setting over-voltage protection system. There are some 'fuses' but these seem to be ok, but there is no voltage on the aux voltage output. Is there something obvious that will have blown? I'm not familiar with SMPSUs and at £17.50 a go, it's probably quicker and easier to replace it, unless there is something obvious I can fix?

Looks like you purchased from the same seller as me, who I notified some time ago that he was supplying these boards configured as 115v.

One of my modules had obviously been plugged into 230v before I received it.

As well as the fuse already mentioned check the 2 surface mount caps across the bridge (D200).

One is fitted between the bridge and the large smoothing caps, the other is fitted to the other side of the PCB. Both of mine were missing having evaporated!

 

[glenn jarrett]

I did think about it, you could run the converter board from the aux power out socket, I used it for the power LED.

The top of the case is a aluminium heat-sink so good small power amps PSU's etc.

We through hundreds away!

Pete

you can throw one my way lol

 

[Julf]

the small blue pcb is the DRV134 single ended to balanced driver

So that is an extra opamp or two in the signal path. Is that really needed?

 

[markvdv]

inputs are single ended, so I think so
drv is said to be a little noisy, no complaints about noise here ?

 

[Julf]

inputs are single ended, so I think so

Ah, so it is not really about unbalanced to balanced, but unbalanced to split-polarity unbalanced.

 

[markvdv]

Yes two single ended inputs requiring opposed polarity for btl. I don't care about additional opamps really, I even looked at http://www.ti.com/lit/ug/tidu034/tidu034.pdf.
Thought about skipping U1b and using that at the output for another U1d for split polarity, don't know if that would work, Icepower seems to want additional resistors from asx ground to unused positive inputs to avoid noise and I need to look a little harder if that will be ok Maybe looking doesn't help

 

[Pete MB&D]

you can throw one my way lol

We possibly have some left if one turns up I will let you know.

Pete

 

[glenn jarrett]

...

 

[glenn jarrett]

thanks Pete

 

[glenn jarrett]

Hi
i have 2 icepower amps which have been modded to btl versions
due to the mod the amps need a balanced input
currently i am running a B4 buffer to DRV134 unbalanced to balanced converter
is there a better way of doing this ?
am i right in saying if i use transformers i will lose audio bandwidth ?

[/url]20170701_113855 by glenn jarrett, on Flickr[/IMG]

 

[JemHayward]

Depends on the transformers - I run my EAR890 balanced and that then passes the signal through a transformer, as the amp itself is SE in stereo mode. It still sounds better than running it SE from my DAC/Pre, but these are transformers from Tim de Paravicini!

 

[glenn jarrett]

they sound expensive !!

 

[Julf]

i have 2 icepower amps which have been modded to btl versions
due to the mod the amps need a balanced input
currently i am running a B4 buffer to DRV134 unbalanced to balanced converter

Not sure I understand your problem. Assuming you have a proper differential/balanced input, nothing special is normally needed. An unbalanced output can drive a balanced/differential input directly. Devices like DRV134 are only needed if you really need the differential drive capability for very long line runs or something.

 

[glenn jarrett]

HI Julf

the B4 has single ended output
what i want to do is find the best way of driving the amps
from what i have read you need a balanced input or a phase splitter for the amp input
apparently both SE and BTL boards are the same apart from the BTL version has the jumper link set to BTL and the components no longer needed removed ( output choke and speaker terminal )
whats the best way to go from single ended to differential
or can i drive it direct from a single ended input

http://www.icepower.dk/files/solutions/icepower50asx2_designersmanual_1-1b_03072012.pdf

http://www.icepower.bang-olufsen.com/files/solutions/icepower50asx2.pdf