Experience with this DIY DAC ?

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#1,662
Hello

Today I could buy some of this famous Toshiba 2SK389 / 2SJ109 double JFET's.

I will make a stripboard layout (with Lochmaster) for a JC-2 preamp (also usable for selected 2SK170 / 2SJ74) and publish here (or in a new thread).

Why?

My actual chinese JC-2 board does not allow balanced input. I will use a JC-2 circuit, allowing balanced input directly from the transformer (as in the original JC-2 circuit).

My best wishes for the new year!
Franz
 
#1,665
Hello

Maybe the Aleph-P or the B1 are better as the JC-2 in this place, as they are true buffers, e.g. gain=1

As I wrote earlier: my line level is too high now, I have to attenuate it more than other sources.

Franz

/Edit
I think, the JC-2 is very suitable for using transformers with a relation about 1:0.6 rather than 1:1

/second Edit
I also must tell you, that I am using a passive pre, e.g. a stepped attenuator between the DAC and the T-amps. Maybe, thats why I have a very big improvement using a buffer after the DAC's output trannies as I am avoiding damping by poor impedance matching within my audio chain.
 
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#1,666
Franz Gysi said:
Hello

Maybe the Aleph-P or the B1 are better as the JC-2 in this place, as they are true buffers, e.g. gain=1

As I wrote earlier: my line level is too high now, I have to attenuate it more than other sources.

Franz

/Edit
I think, the JC-2 is very suitable for using transformers with a relation about 1:0.6 rather than 1:1

/second Edit
I also must tell you, that I am using a passive pre, e.g. a stepped attenuator between the DAC and the T-amps. Maybe, thats why I have a very big improvement using a buffer after the DAC's output trannies as I am avoiding damping by poor impedance matching within my audio chain.
Click to expand...


Franz

May I ask something about this.

What if I have a passive pre like the LSA then using a buffer like B1 buffer, would that combination will improve the DAC with output transformer just like you have in your latest setup with the JC-2 output stage ?
 
#1,669
Hi,

im interested in this dac-kit here (link)

im quite new here and didnt follow this thread before, can you maybe tell me what I have to change on this dac to make it sound very good? I dont feel like reading 167 pages 🙁

I already read before, that this dac may have problems with certain preamps, im planing on building a preamp with pga 2311 (lsqr 2.0, its from a german forum) as preamp, might this be a problem?

greetings,
Chris
 
#1,670
Chris

Try this DAC and don't use the analogue output section (the opamps). Attach a fine 1:1 line trannie directly to the CS4398's outputs.

For example a Lundahl LL1540.

Then relax and listen.

After that experience, you could add a passive low pass filter and/or, as I am experimenting actually, a fine buffer.

The best wishes for the new year
Franz

/Edit: there are no problems with "certain preamps"
 
#1,671
Hi Franz,

thx for your answer, i think i will try the line trannie option first. lets see what I can find about the lundahl.

is it the "best" one? or are there better ones? i think i dont want to buy such a line tracie for $500 when the dac itself only costs 110$ with shipping, that wouldnt make that much sense 🙂

lets say im searching for the best "bang for the buck", thats at least what the people at head-fi say 😀

and of course: best wishes for the new year 😉

edit: i just found out there are different versions of this lundahls from 23-111 over 23-112 and 23-113 and 23-131
which is the right one?
 
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#1,675
i didnt mean that the lundahl you mentioned first would cost $500, just said that i dont want to buy such an expensive line transformator...

can you maybe tell me which toroid transformator i need?

edit:

i found this one here:

Print-Netz-Trafo prim 230 V
sek 1 = 8 V 1,6 VA sek 2 =13 V /8,6 VA
size L=50, B=42, H=34 mm.

Typ U 8311 1 St. 1,75 €

adress/shop(german)
 
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#1,676
@Chris
If you are using transformers instead of opamp outputs you don't need the power supply for them. 6-8VAC is enough to power the DAC, something like this (from the website you supplied):

Print Netz Trafo
prim 230 V,
sek1=8 V 15 VA
sek2=8 V 15 VA
Maße: L= 63 , B = 54, H= 54 mm.
Typ U 4062 1 St. 4,25 €

Of course you only need one 8V secondary, not two like this one, but it doesn't matter, no one forces you to connect the other one 🙂

And for the line transformers my suggestion are the UTC A-20, they go around 100$ on ebay and sound great.

Here is a pic of my DAC, changed almost everything, currently playing with LPF filters:
An externally hosted image should be here but it was not working when we last tested it.
 
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#1,677
if i dont buy a transformator that can also deliver 13v i cant even test the dac, if i make changes and solder some stuff on this dac and then realize it doesnt work my warranty will be gone i dumped $110
so i need a transformator with 8v and 13v... this is not so good but i dont want to risk anything

And for the line transformers my suggestion are the UTC A-20, they go around 100$ on ebay and sound great.
Click to expand...

hm well $100 is a bit too much for my taste. i think ill prefer to try cheaper ones first but thx for ur suggestions!
 
#1,680
Hey hey, confusion!

There is no need for I/V conversion outside of a CS4398. It's a voltage out DAC.

The redline in this thread is talking about using 1:1 trannies connected directly to the CS4398 instead of the analog opamp circuit.

When using 1:1 trannies, then you will have the full scale line level mentionned in the CS4398 datasheet (and about 1% loss).

Franz
 
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