Hi guys,
my gigawork DAC 2010-version just arrived and i am very happy. I've tried to remove some electrolitycs but i've destroyed the tracks. Do you have any solution to this because i want to install some oscons around chips.
Changes so far: exchanged the i/v convertors to LME49720 and buffer to AD823 (also tested OPA2104). Sounds good but i want more 🙂
I'm comparing with Marantz 60 (tda 1541) NOS and noded also lampized (sweet sound).
my gigawork DAC 2010-version just arrived and i am very happy. I've tried to remove some electrolitycs but i've destroyed the tracks. Do you have any solution to this because i want to install some oscons around chips.
Changes so far: exchanged the i/v convertors to LME49720 and buffer to AD823 (also tested OPA2104). Sounds good but i want more 🙂
I'm comparing with Marantz 60 (tda 1541) NOS and noded also lampized (sweet sound).
Hi,
thanks to your help I got my DAC working. I am not an expert so my contribution can be just to show my casing solution.
I just assembled the DAC as received, without updates. Into my opinion it sounds good, but not great.
No hum, sound very dynamic, in particular bass especially if compared
with my DAC Supepro 707 based on the CS4398 dac chip. However
the output level is very high, my chipamp has the volume set at 8-9 o'clock and I got the impression that, when the music is loud,
there is an audible distortion. Looking back in this thread I found that other people had the same impression.
To improve the sound I found here essentially three suggestions:
1- completely change the output stage (which is too complicated for my skill);
2- change the transformer to 2x15VAC instead of 2x12AC (I do not like since I already have a 12VAC trafo, but I could do of course);
3- Change the 3 op-amp in the output (now AD827JN as shipped).
Option 3 is the one I would prefer, but does it really give an improvement in the sound?
I am a bit concerned because for instance one of the suggested option, OPA627, costs more than 20€ (each op-amp) on Mouser:
the update is more expensive than the complete DAC!
Your opinions are really welcome
Thank you
Renato
thanks to your help I got my DAC working. I am not an expert so my contribution can be just to show my casing solution.
I just assembled the DAC as received, without updates. Into my opinion it sounds good, but not great.
No hum, sound very dynamic, in particular bass especially if compared
with my DAC Supepro 707 based on the CS4398 dac chip. However
the output level is very high, my chipamp has the volume set at 8-9 o'clock and I got the impression that, when the music is loud,
there is an audible distortion. Looking back in this thread I found that other people had the same impression.
To improve the sound I found here essentially three suggestions:
1- completely change the output stage (which is too complicated for my skill);
2- change the transformer to 2x15VAC instead of 2x12AC (I do not like since I already have a 12VAC trafo, but I could do of course);
3- Change the 3 op-amp in the output (now AD827JN as shipped).
Option 3 is the one I would prefer, but does it really give an improvement in the sound?
I am a bit concerned because for instance one of the suggested option, OPA627, costs more than 20€ (each op-amp) on Mouser:
the update is more expensive than the complete DAC!
Your opinions are really welcome
Thank you
Renato
Today i've made some mods and decided to keep AD827 for I/V conversion and AD823 for buferring/filtering but after i tried to put the last opamp in A-class mode with biasing resistor everything went bad.
Ived after disconnecting the biasing resistor my DAC is tottaly quiet. The blue led is lit so he is locked to the Spdif signal but no audio on the PCM 1798 outputs. I suppose somehow suddenly the PCM died.
Any other ideas ?
Today i ordered some PCM 1794 so i will try to exchange the PCM 1798 iven if the PCB is sesitive like hell and so easy to destroy the tracks.
Ived after disconnecting the biasing resistor my DAC is tottaly quiet. The blue led is lit so he is locked to the Spdif signal but no audio on the PCM 1798 outputs. I suppose somehow suddenly the PCM died.
Any other ideas ?
Today i ordered some PCM 1794 so i will try to exchange the PCM 1798 iven if the PCB is sesitive like hell and so easy to destroy the tracks.
of course you can change the AD with lm and/or OPA. I tried many combinations before my DAC stopped working.
I had this problem and it was solved by the suggestion in post #92 of this thread. Now the input on my pre is no longer overdriven.
Hello Renato.
Another post with information.
http://www.diyaudio.com/forums/digital-line-level/186243-anyone-finished-gigawork-dac.html
In a Lampucera DAC is mandatory: short cut the HEF4053BT as shown in the picture:
It is an analog switch that performs CS8416 mute. It mute OPA output to RCA connector. It is very simply: put two drops of tin. Very ease and very important.
In these pictures you can see the difference in short-circuit, the photo 4 only has short circuit, the most important modification.
The digital input signal is 0 dB 1 kHz. sinewave.
Other audible modifications:
- Change OPA (I think those who come AD827 are not original) I have many different OPA. All good measure, some OPA better than others, but with little audible differences among them. AD827 on the kit are worst measure, quite different from the rest. the worse sound. There are differences, but not interesting OPA expensive 2134 or 2604 for example, is sufficient.
- 4 parallel 470 Oh. resistors R27, R28, R29, R30. Signal level drops to similar values than commercial CDs. Low distortion on maximum output level of the DAC. Betther sound and measures. I think it's very interesting improvement.
Other change hadn't been no improvement: SPDIF input transformer, capacitor change, add condenser, up to 15 vol. modify SPDIF, etc. I have done all and sound is the same.
Another post with information.
http://www.diyaudio.com/forums/digital-line-level/186243-anyone-finished-gigawork-dac.html
In a Lampucera DAC is mandatory: short cut the HEF4053BT as shown in the picture:
An externally hosted image should be here but it was not working when we last tested it.
It is an analog switch that performs CS8416 mute. It mute OPA output to RCA connector. It is very simply: put two drops of tin. Very ease and very important.
In these pictures you can see the difference in short-circuit, the photo 4 only has short circuit, the most important modification.
The digital input signal is 0 dB 1 kHz. sinewave.
An externally hosted image should be here but it was not working when we last tested it.
Other audible modifications:
- Change OPA (I think those who come AD827 are not original) I have many different OPA. All good measure, some OPA better than others, but with little audible differences among them. AD827 on the kit are worst measure, quite different from the rest. the worse sound. There are differences, but not interesting OPA expensive 2134 or 2604 for example, is sufficient.
- 4 parallel 470 Oh. resistors R27, R28, R29, R30. Signal level drops to similar values than commercial CDs. Low distortion on maximum output level of the DAC. Betther sound and measures. I think it's very interesting improvement.
An externally hosted image should be here but it was not working when we last tested it.
Other change hadn't been no improvement: SPDIF input transformer, capacitor change, add condenser, up to 15 vol. modify SPDIF, etc. I have done all and sound is the same.
Last edited:
Hi,
thank you for the suggestions. I am going to make the mods. Since I am a little bit afraid of touching the pcb I'll try the post #92 mod at first.
Thank you again
Renato
thank you for the suggestions. I am going to make the mods. Since I am a little bit afraid of touching the pcb I'll try the post #92 mod at first.
Thank you again
Renato
Hi,
I apologize for my stupid question, but I would like to test different op amps like the OPA627 or LM4562.
I understood I need the dip type, but then on the net I see option like dual or mono, etc. and I get confused on what to buy.
I found for instance OPA627BP or OPA627AU, LM4562NA, LM4562MA are they all OK?
Thank you
Renato
I apologize for my stupid question, but I would like to test different op amps like the OPA627 or LM4562.
I understood I need the dip type, but then on the net I see option like dual or mono, etc. and I get confused on what to buy.
I found for instance OPA627BP or OPA627AU, LM4562NA, LM4562MA are they all OK?
Thank you
Renato
OPA627-series are mono, you need to combine 2 to 1, please see the photo.
The timbre of OP-AMP must match the timbre of your power-amp, or they can not be OK. I have 2 power-amp, Krell and Harman Kardon, I use LT1361 for Krell and 2107SM for Harman Kardon, it's perfect match, and it will be a disaster if I swap it.
An externally hosted image should be here but it was not working when we last tested it.
As i distroyed the PCM 1798 replaced de DAC with PCM1794 received as a sample from TI and i want to say that i am more than happy. But i will be super happy after tube-isation . The opmaps sounds very good but soooo boring (too precise for me).
Also i've replaced the elco's with oscons in digital area and elna's in analog area.
So can anybody tell me how to make the I/V conversion and connect some tube SRPP stages ?
I have experience with tube-isation of TDA 1541 but this one is not simetric like pcm1794.
Also i've replaced the elco's with oscons in digital area and elna's in analog area.
So can anybody tell me how to make the I/V conversion and connect some tube SRPP stages ?
I have experience with tube-isation of TDA 1541 but this one is not simetric like pcm1794.
Atupi,
My pcm1798 also dead because of my mistake, is pcm1798 and 1794 pin compatible? There are 2 type of 1794 chip: pcm1794DB and pcm1794ADB, are them the same?
Thank you.
My pcm1798 also dead because of my mistake, is pcm1798 and 1794 pin compatible? There are 2 type of 1794 chip: pcm1794DB and pcm1794ADB, are them the same?
Thank you.
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Yes they are pin compatible and the termination is regarding how they are packed. You can use anyone of them.
Hi, is there a thread on the older (CS4397) based version of this DAC at all?
I've got few of these, and was wondering if this:
VXI POWER|14443-000|PSU, ENCAPSULATED, 5V, +/-12V | Farnell United Kingdom
Would give enough current to power it including a single op-amp? Would 300mA on the 5v rail be enough?
Thanks. 🙂
I've got few of these, and was wondering if this:
VXI POWER|14443-000|PSU, ENCAPSULATED, 5V, +/-12V | Farnell United Kingdom
Would give enough current to power it including a single op-amp? Would 300mA on the 5v rail be enough?
Thanks. 🙂
Bad ground?
I've got some wonderfull sound coming out of this unit, still using stock op amp but changed lots of the capacitors.
However...
Whenever I change the volume control (stepped attenuator on a Audible illusions pre-amp) there is a thump coming thru the speakers at each detente.
It also happens when I change the selector switch to CD or from CD.
The thump is not loud, but is unaffected by volume control position.
Using the dac with a recently made shigaclone
???
Thanks,
Paul
I've got some wonderfull sound coming out of this unit, still using stock op amp but changed lots of the capacitors.
However...
Whenever I change the volume control (stepped attenuator on a Audible illusions pre-amp) there is a thump coming thru the speakers at each detente.
It also happens when I change the selector switch to CD or from CD.
The thump is not loud, but is unaffected by volume control position.
Using the dac with a recently made shigaclone
???
Thanks,
Paul
Did you run any of the suggested tests to figure out if your problem is related to grounding? Connected the ground of all your devices together? Got the option of running optical?
It's possible the ground of the DAC and pre-amp are at different levels and that thump is your speakers jumping from one DC level to another.
I am using the stock power supply. This isn't grounded. Should I connect a ground wire from the ground lug (phono) on the preamp to a ground spot on the curcuit board of the DAC?
DAC and Shigaclone are mounted together on a granite slab with wood cover. So I didn't do any grounding to either. They are both two prong polarized plugs.
No optical
Thanks,
Paul
DAC and Shigaclone are mounted together on a granite slab with wood cover. So I didn't do any grounding to either. They are both two prong polarized plugs.
No optical
Thanks,
Paul
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