Hi
Have a look to the AD1862 thread where a lot of modern opamp were tested. This dac chip is close to the pcm63. The 2604 will be too much soft with your chip that is subjectivly already soft and mellow in the mids. You might want to try some bipolar input oaps too or transconductance oap like the opa861.
Have a look to the AD1862 thread where a lot of modern opamp were tested. This dac chip is close to the pcm63. The 2604 will be too much soft with your chip that is subjectivly already soft and mellow in the mids. You might want to try some bipolar input oaps too or transconductance oap like the opa861.
if you can, drop the I/V shematic and photograph of this area of your DAC and what is after till the RCA output.
It will help people to help you more. It deserves a dedicated thread. Your oap is a dip8 but there are also adaptator pcbs for soic smaller casing oaps for them to stack on a DIL8 area. In the Miro1360 thread about ad1862 dac chip you can find free gerbers to make them printed by a pcb maker, they are cheap nowadays. And mostly you willl see the best oaps from today discussed in the thread.
only problem with some modern oaps is than they are not too much suited because oscillations issues when being on DIL8 socket people use to swap easily oaps for listening benchmark.
You could for instance try an opa1612 or 1602 on such adaptator
It will help people to help you more. It deserves a dedicated thread. Your oap is a dip8 but there are also adaptator pcbs for soic smaller casing oaps for them to stack on a DIL8 area. In the Miro1360 thread about ad1862 dac chip you can find free gerbers to make them printed by a pcb maker, they are cheap nowadays. And mostly you willl see the best oaps from today discussed in the thread.
only problem with some modern oaps is than they are not too much suited because oscillations issues when being on DIL8 socket people use to swap easily oaps for listening benchmark.
You could for instance try an opa1612 or 1602 on such adaptator
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Notice you certainly have with the EL2160 a bipolar single chanel oap for the I/V task. I'd keep them ! Monarchy was a good brand and they know what they did.
Forget perhaps what I have said. you can try JFet oap as well to swap the op2604 (perhaps filter task here ?) next EL2160 stage. Can try a soic opa1656 or 1646 on a DIL8 adaptator or of course a DIL8 oap.
So you mean that the right part of the board behind the output plugs are for XLR only and the RCA are bypassed from this stage ? Or you btpassed it ?
hummm better to open a thread and not hack this one imo for further advices..
Forget perhaps what I have said. you can try JFet oap as well to swap the op2604 (perhaps filter task here ?) next EL2160 stage. Can try a soic opa1656 or 1646 on a DIL8 adaptator or of course a DIL8 oap.
So you mean that the right part of the board behind the output plugs are for XLR only and the RCA are bypassed from this stage ? Or you btpassed it ?
hummm better to open a thread and not hack this one imo for further advices..
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well without any shematic, we are a little in the augures thingies 
... a curent buffer ah, why not it sounds fine on the paper . Maybe Abraxalito can says that, it's above my head... but at 1 mA output the dac chip is needing a little help ... one want this stage to lower the outputt impedance as well if I understood.
Its ad1862 close brother however works fine with one oap only as an I/V and a line buffer with a single oap !
... a curent buffer ah, why not it sounds fine on the paper . Maybe Abraxalito can says that, it's above my head... but at 1 mA output the dac chip is needing a little help ... one want this stage to lower the outputt impedance as well if I understood.Its ad1862 close brother however works fine with one oap only as an I/V and a line buffer with a single oap !
uh... it's the beginning of the end, my brain memory is falling.thanks Joseph for the correcting ! Btw, have you finally bought some AD1862 dac chip from Rochester viaPady Garcia ? It deserves it for your dac chips collection !
Though with these ESS dac chip new topping dac or Okto dac that works fine with PCM materials... I could give up the quest maybe
(Could be fun if the japaneese guy behind the diy AK dac had projects around the ESS9038 pro !)
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Swapping the OP IC's will not bring any major improvements.
Ther are 3 areas that you could focus on (pretty much the case with any DAC):
- have a look here, Lundahl is used with a Cadoc as an I/V, with PCM63. This will sound better than IC's... DAC by Armonia Hi-Fi
- There are 3-legged voltage regs on that PCB that could be replaced with something better, like LT3045 direct drop-in replacements (pending the Vin and Iout/Pdis are within the acceptable level)
- there is an Xtal oscillator there as well - you could try a different oscillator with very low jitter and phase noise.
The above will bring marked improvements to your DAC... but require time and money... Is it worth?? sound wise - yes; return on investment?? probably not... you may be able to buy a consumer DAC (just for the cost of mods alone) that will sound good, but will give you USB in, DSD/PCM options... and then you can try HQPlayer with it... it could be a revelation...
Ther are 3 areas that you could focus on (pretty much the case with any DAC):
- have a look here, Lundahl is used with a Cadoc as an I/V, with PCM63. This will sound better than IC's... DAC by Armonia Hi-Fi
- There are 3-legged voltage regs on that PCB that could be replaced with something better, like LT3045 direct drop-in replacements (pending the Vin and Iout/Pdis are within the acceptable level)
- there is an Xtal oscillator there as well - you could try a different oscillator with very low jitter and phase noise.
The above will bring marked improvements to your DAC... but require time and money... Is it worth?? sound wise - yes; return on investment?? probably not... you may be able to buy a consumer DAC (just for the cost of mods alone) that will sound good, but will give you USB in, DSD/PCM options... and then you can try HQPlayer with it... it could be a revelation...
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Seems more likely its doing I/V duty here. I downloaded its DS, the weakness of this part in this position would seem to be its too noisy (5.1nV/rtHz voltage noise).
I'd suggest another CFB opamp to substitute but a quick calculation shows even AD811 - with much lower voltage noise - would be more noisy in practice due to its higher current noise (20pA/rtHz). Noise seems to be an issue with all CFB ICs in this application.
Do you think the op1611/12 could suit instead despite it needs a lossy soic to dil adaptator ? Then for the opa2604 a 1656?
@E-bokys....the jrc 3 legs are good enough if you lower the impedance at its output and decouple it at its input by a low esr cap. The output cap seems blue Elna that has not so good esr which is what you look for here and you can even degrade it by a serie resistor of a very low Z. But having aged the Elna should be ok if at the output.
There is way better than the caddock at this task and being important it is less than oaps from what I experienced.
There is way better than the caddock at this task and being important it is less than oaps from what I experienced.
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OPA1611 might suit yes. Its lower noise than the Elantec but not as high speed so might run into slew limiting at the DAC transitions. I'd prefer an OPA1642 to the OPA1656 due to lower low frequency noise. I found its poorer sister (OPA1678) too bass light for my taste but haven't listened to OPA1656 myself.