Experience with this DIY DAC ?

Jump to Latest
Franz Gysi

Franz Gysi

Member
Joined 2007
BTW:

Why do most of us (I don't) live with this SPDIF/RCA compromise?

SPDIF stands, as you may know, for Sony Philips Digital InterFace.

At the time of development of SPDIF, a AES/EBU derivate for consumer equipment, Philips had the intention to use BNC connectors.

But Sony insisted on RCA's, as they are common in consumers environement.

Thanks Sony!

Franz
 
X

xTr3Me

Member
Joined 2007
well all that spdif-trouble doesnt make that much sense to me. my m-audio 2496 has normal rca plugs for spdif output. i think m-audio is intelligent enough to know about digital cables and the 75ohm bnc connectors. but they didnt use a bnc connector, the use a simple rca connector. this means to me that a normal rca cable is good enough.
 
K

kesa32

Member
Joined 2006
re the Cinemags : thanks for the replys on this, l guess my main thoughts are about phase shift differences in these trannys.....theCOMQ-2H is +1 @ 20hz , -5 @20khz ..........whereas another model l was looking at , COMB-2H is +2 @ 20hz , -0.5 @ 20khz .
Will this make an make an audible difference if the phase shift is more or less on these? , l know datafone likes his CMOQ-2h's that he's using and l'm about to order from Cinemag, so this is the only thing holding me up .
David @ Cinemag wrote this in regards to quadfilar vs bifilar tannys :

The CMOQ-2H windings can be hooked up in series for higher dcr, or in parallel if your circuit can drive the load. It is very hard to recommend one over the other since we have not had the opportunity to listen to them and compare. Sorry that I cannot be more helpful on this one.
Cheers,
David



Cheers ken
 
Franz Gysi

Franz Gysi

Member
Joined 2007
well all that spdif-trouble doesnt make that much sense to me. my m-audio 2496 has normal rca plugs for spdif output.
Click to expand...

As I wrote above: it's in the specs of SPDIF because Sony insisted on it.

So, M-Audio did a good job.

SPDIF is better with a good 75 coax, at least 1.5m long, and BNC connectors. Definitely.

But the CS8416 receiver is not as sensitive to jitter as other receivers.

Conclusion in the context of the Gigaworks DAC, what this thread is about: RCA is O.K. for SPDIF input.

Franz
 
Last edited:
X

xTr3Me

Member
Joined 2007
hi franz,

then i got you wrong, sorry!

chris

edit:
pic of my finished dac:
ill only change the digital input to spdif... :p
img_59701xkm.jpg
 
Last edited:
L

lbj

Member
Joined 2009
kesa32 said:
re the Cinemags : thanks for the replys on this, l guess my main thoughts are about phase shift differences in these trannys.....theCOMQ-2H is +1 @ 20hz , -5 @20khz ..........whereas another model l was looking at , COMB-2H is +2 @ 20hz , -0.5 @ 20khz .
Will this make an make an audible difference if the phase shift is more or less on these? , l know datafone likes his CMOQ-2h's that he's using and l'm about to order from Cinemag, so this is the only thing holding me up .
Click to expand...
Earlier this week I placed an order for the CMOB-2H. I pored over the CMOB/CMOQ data sheets and the only real difference I could see was the phase angle graphs looked a lot better on the CMOB. I'm also skeptical of any audible difference of phase, but since the CMOB was slightly cheaper too I went that direction. When I've received them and hooked them up I'll report back.
 
B

Bill Fuss

RIP
Joined 2005
McCrackers said:
Hey Bill,
Sounds interesting.
I'm still trying to figure out this I2S thing, which appears to be a significant step up, and hoping someday to be able to use it with my SB3. K & K Audio are offering an I2S interface adapter but I have no idea on how to implement it. As they state:we strongly recommend that the I2S Interface Adapter Send board be used only by someone who has the necessary knowledge and skills to undertake the project without guidance.

I've been using inexpensive BJC with Belden 1505F for a while and have found it to be quite good also. Especially when I look at the price that some cable manufacturers are asking for their "revolutionary new design" stuff.
Click to expand...

That was a great idea from ZM, I never considered the F-cons. 1505F should work too, it has the right inner diameter.

I been reading up on I2S, it's the original Philips internal format that keeps the clock and the data separate. You have data, bit clock, and word select (goes hi or low depending on whether left or right ch. data), and ground. These days the term I2S is pretty much generic but some manufacturers are cooking up their own iterations for external use.

From what I've read, both the 8421 and 4398 chips can be fed from almost any form of I2S. This would completely eliminate the inherent problems in the SPDIF format, but takes the multiple inputs of the 8416 away.
Feeding the 8421 directly, I don't know how much improvement to expect because it reclocks the data anyway with its own clock. Feeding the 4398 directly would take a master clock feeding the source and the chip (synchronous) so an external interface could be a PITA. I'm planning on installing the dac board in the player housing, keeping all wiring as short as possible, and using a new clock for the whole works.

McCrackers, the SB3 must use some form of I2S internally, what dac chip do they use in it. Also, if it's voltage out you could try trafos with the present dac chip.

This digital stuff is pretty deep for me so follow at your peril.

There's lots of smart guys with digital chops on this forum, I hope some will chime in.

Bill
 
H

hoverdonkey

Member
Joined 2009
Yes, that is a great idea to use F connectors - continuity of impedence with very little cost and bother.

Here is an explanation of why longer SPDIF cables might be better. I don't pretend to fully understand it but there does seem to be logic behind it. I note that the author agrees with Franz Gysi's 1.5m for min cable length (not quite not my previously posted 3m :eek: - naturally, I can't now find the thread where that was recommended).
 
M

McCrackers

Member
Joined 2009
Bill Fuss said:
McCrackers, the SB3 must use some form of I2S internally, what dac chip do they use in it. Also, if it's voltage out you could try trafos with the present dac chip.

This digital stuff is pretty deep for me so follow at your peril.

There's lots of smart guys with digital chops on this forum, I hope some will chime in.

Bill
Click to expand...

It's a PCM1748. In stock configuration it doesn't sound that great. I don't see what would be gained by using it over an external DAC with CS4398 even with trafos. Unless the output circuitry is what's limiting its performance.

Basically what I'd like to do is to obtain the cleanest possible signal from the SB and feed it to my external DAC. I've read a few discussions on it and a few people are doing it commercially so it definitely can be done.

Due to my lack of experience I guess I'll have to hold off on this one until I can find a step by step or someone who has the patience of a Buddhist monk to "spoonfeed" me through the entire procedure.:D
 
K

kesa32

Member
Joined 2006
lbj said:
Earlier this week I placed an order for the CMOB-2H. I pored over the CMOB/CMOQ data sheets and the only real difference I could see was the phase angle graphs looked a lot better on the CMOB. I'm also skeptical of any audible difference of phase, but since the CMOB was slightly cheaper too I went that direction. When I've received them and hooked them up I'll report back.
Click to expand...

Yeah l think l'll go the COMB-2H's as well , as l like the more linear phase aspect of them.......otherwise as you say.they're much of a muchness

cheers ken
 
A

alboran

Member
Joined 2007
greetings to all :D
after reading 200 pages of the thread.. and not having slept whole nights to monitor eBay auctions ...
I finally bought all the transformer that I thought were suitable for the output of my buffalo DAC !
namely:
UTC HA-108 for tension mode
Audio Tekne LT-8310 for tension mode
Jensen Jt11P1 for tension mode
UTC HA-101 for current mode
Stevenson & Billington TX-103 for current mode

advise me how different processors, to run the big test ....:eek:
course I'll tell you what results I get ;).
thanks and greetings
 
D

data

Disabled Account
Joined 2007
Interesting...

The site isn't giving me any links to that models data-sheets or any other documentation, I wonder if it is because I'm using Firefox?

Though it is listed under Line Input transformers, but with no links.


So this is from the data-sheet for a transformer that is specific to the application of balanced to unbalanced signal?
Is this also a step-up transformer being 10k/600ohms?
 
M

McCrackers

Member
Joined 2009
I have Jensen JT-11P-1 and Cinemag CMOB-2L on order. Both are due late next week. The JT-11-BMCF looked interesting but were a bit too expensive for an unshielded trafo. Jensen has a Canadian distributor who sells at par so it's a bit of a bargain for me. Don't lose on the exchange plus faster/cheaper shipping without duty.
I notice Lundahl popularity seems to have faded a bit around here. Is it the price?
 
You must log in or register to reply here.
Top Bottom