Experience with this DIY DAC ?

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#1,321
anbello said:
I bought 4 Monacor LTR-110 to do some experiments with this DAC and a Buffalo24 from Twisted Pear.
For now i have connected the + and - DAC out directly to the primary of the LTR-100 and the secondary to RCA with a 10K resistor in parallel for both DACs.
I attach the results of measurement done with RMAA.
Next i will try a better way of connecting the transformer to the DAC (something like the way descripted by GerardA on post #1285)
Anyway i can say that i really like these transformer out DACs, it seems to me the Buffalo24 is a little bit better in detail and in the positions of the instruments on the soundstage.

Ciao
Andrea

(on the left CS4398, on the right Buffalo24)
Click to expand...
Anbello,
I'm interested in your results with transformer output on the Buffalo - what o/p stage were you comparing to IVY or Counterpoint? The RMAA Freq response & THD don't look particularly good for the Buffalo, did you change the o/p transformer config yet & take more measurements?

Thanks Bill, I was confused for a minute!
 
#1,323
johnm said:
OK I have just modded my 'BIG' Dac and...... all I can say is if you have one you MUST try this. Sitting here with a BIG grin on my face!

All I did was remove op-amp nearest the edge of the circuit board, and replaced the one nearest the center with a single LM4562.

I then replaced all the four caps nearest that chip (marked L+ / L- / R+ / R- ) with wire links.

I then soldered a wire from pin 1 of the op-amp to the left output socket, and pin 7 from LM4562 to right output socket.

So if you don't like this tweak it is easily reversable and no harm done... I somehow think you will keep it like this though 😉

Seldom heard digital sound so good..... superb! No obvious problems with the lack of a muting circuit either thus far.

** NO resistors needed to be removed on my board, like Kevin's. But you may need to check your particular board as there are some variations **
Click to expand...


I just have a quick question please.

I've recently purchased this DAC and would like to perform the above mod, but I'm wondering is it possible to do it with the default OP-amp installed, or is it absolutely necessary to replace the one remaining NE5532 with a LM4562?

I really appreciate the help, cheers.
 
#1,324
A-20 filter circuit

Besides Jensen recommended filter circuit on output transformer, can any body here share your best circuit to implement primary and on secondary for the A-20.....

Secondly

Is this the PPL filter that need to be change to 3R, 22nF and 1nF?

An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
 
#1,325
jkeny said:
Anbello,
I'm interested in your results with transformer output on the Buffalo - what o/p stage were you comparing to IVY or Counterpoint? The RMAA Freq response & THD don't look particularly good for the Buffalo, did you change the o/p transformer config yet & take more measurements?
Click to expand...

Hi jkeny,
i didn't compare the Buffalo24 with other o/p stage cause i have only the IVY PCB and the components but i didn't find the time to build it.
Till now no try with other transformer config, when i will do it i will refer here with comments and measurements.

ciao
andrea
 
#1,326
Bosk said:
I just have a quick question please.

I've recently purchased this DAC and would like to perform the above mod, but I'm wondering is it possible to do it with the default OP-amp installed, or is it absolutely necessary to replace the one remaining NE5532 with a LM4562?

I really appreciate the help, cheers.
Click to expand...

It's not necessary at all, but most people find replacing the NE5532 is an improvement. Since op-amps are pretty cheap and they're easy to remove/fit I'd say there's not much reason not to make the change.

Still the best improvement is by far ignoring all the above and going for a pair of output transformers.
 
#1,327
Bill Fuss said:
The drawing is not what is shown in the previous pic. The drawing is OK except for the size of the caps. I hope his dac chip is not fried.
Click to expand...

Well I tried a coaxial input and the buzzing stopped. Still very low volume sound. Almost like when you're only getting sound through a tweeter. I pulled off the CS4398 and lo and behold at some point I had broken off a pin. Probably the last time I took it off. According to the CS4398 datasheet it's the VLC pin. Dunno if that's the problem.
Oh well.

I think I'm going to cut my losses. Too many projects at once and I'm making too many mistakes🙁🙁. I'll be selling the A-20s if anyone is interested.
 
#1,328
johnm said:
It's not necessary at all, but most people find replacing the NE5532 is an improvement. Since op-amps are pretty cheap and they're easy to remove/fit I'd say there's not much reason not to make the change.

Still the best improvement is by far ignoring all the above and going for a pair of output transformers.
Click to expand...

Thanks for your help johnm. 🙂

I'm curious to hear just how good this DAC can sound using op-amp output, and will go ahead and perform the mod. I'll order a replacement op-amp and whack it in down the track when it arrives.

I am rather keen on the transformer mod also, but it seems to be a fairly costly mod. If the improved op-amp output doesn't satisfy me I'll look into buying some transformers.
 
#1,329
gabanyayaya said:
Besides Jensen recommended filter circuit on output transformer, can any body here share your best circuit to implement primary and on secondary for the A-20.....

Secondly

Is this the PPL filter that need to be change to 3R, 22nF and 1nF?

An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Click to expand...

That looks like the right PLL components, but follow the traces to be sure, my board isn't exactly the same.

Regarding the output arrangement, who's to say what is best, just don't load anything down too much. The trafos don't need a secondary load more than your preamp input circuitry, and the 4398 cant handle a big current draw so keep some resistance in each leg, 250, 500, 1k, whatever you like.

Best, Bill
 
#1,330
Bill Fuss said:
That looks like the right PLL components, but follow the traces to be sure, my board isn't exactly the same.

Regarding the output arrangement, who's to say what is best, just don't load anything down too much. The trafos don't need a secondary load more than your preamp input circuitry, and the 4398 cant handle a big current draw so keep some resistance in each leg, 250, 500, 1k, whatever you like.

Best, Bill
Click to expand...

Bill

PPL component consist of 3R resistor and some 22nf and 1nf....Which one is the right R...? This board is freaking hard to read the traces....😕 Is there a big improvement by doing this?

BTW for those who wish to add pulse transformer you can used the empty area next from the coax. input either for Sumlink or Newava. I trace the link as in the picture. Just unconnected the solder blob between coax. input and 10nJ100....make sure you know the leg oriented for the tranny....

An externally hosted image should be here but it was not working when we last tested it.


[img=http://img203.imageshack.us/img203/5822/dsc00112w.th.jpg]
 
#1,333
As I promised, here is the report: Monacor LTR 110 used as per GerardA's advice worked out quite nicely in first attempt! Happy puppy over here! Sounds really nice, but I'll have to listen for some time to make conclusions. Capacitors used are not exactly the values GerardA sugested - 6.8 instead of 7 nF and 3.3 instead of 3 nF. Is that important?
This thread and forum in general are great - keep up the good work people!
 
#1,336
dac-b1-xo-tamp

Yes volume,

My idea would be to build the dac+B1 together and connect this to a balanced active crossover/ T-amp powered loudspeaker.

Before reading this idea I wanted to do the same and put transformers between dac and B1.

Less = more so the transformer free version is preferred if sounding equally good.

Cheers Peter
 
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