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GUSTARD DAC-R26 Balanced Decoder R2R+1Bit Dual Native Decoding Music Bridge
- Thread starter m-i-c-k-e-y
- Start date
sajunky
Headphoneus Supremus
Sorry, I trust my eyes, not Currawong.
sajunky
Headphoneus Supremus
Commenting on the Currawong video:
1. He points to different opamp chips, located on the main board. I refered to those as well, saying that I wouldn't jugde from the photo.
2. He suggests servo use, but not making a statement. For me it is nonsence, as for servo use one opamp chip would be sufficient generating offsets for both channels.
In my view these opamps are very likely in the audio path as well. If there are opamps on the ladder board, to which I have no doubt, we can find more, this is a simple deduction. In fact there is a very extensive bypassing with four red blocks of Wima caps plus two large electrolyte caps per opamp chip. If it were for a different purpose, such extensive bypassing wouldn't make engineering sense.
1. He points to different opamp chips, located on the main board. I refered to those as well, saying that I wouldn't jugde from the photo.
2. He suggests servo use, but not making a statement. For me it is nonsence, as for servo use one opamp chip would be sufficient generating offsets for both channels.
In my view these opamps are very likely in the audio path as well. If there are opamps on the ladder board, to which I have no doubt, we can find more, this is a simple deduction. In fact there is a very extensive bypassing with four red blocks of Wima caps plus two large electrolyte caps per opamp chip. If it were for a different purpose, such extensive bypassing wouldn't make engineering sense.
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BShaw
1000+ Head-Fier
Sure looks like an opamp to me right at the base of each ladder, right at the head of the output stage? Then in the first photo, there are two perched there just before the balanced outs. Bummer. Guess it's time to rob a bank and go get a Holo May 
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sajunky
Headphoneus Supremus
I think a discrete buffer follows filtering section based on opamps, these transistor circuits on edges. You can read Gustard advertising "some discrete design".Sure looks like an opamp to me right at the base of each ladder, right at the head of the output stage? Then in the first photo, there are two perched there just before the balanced outs. Bummer. Guess it's time to rob a bank and go get a Holo May
vinylvalet
Member of the Trade: Big Ear Stereo, The Vinyl Valet
Silly audiophile myth #420: All opamps and/or all circuits designed with op amps can't sound as good as a discrete circuit.
sajunky
Headphoneus Supremus
Well, opamps are not so very bad in Delta-Sigma DAC (except the output buffer), while R2R DAC require better amplification.
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m-i-c-k-e-y
Headphoneus Supremus
Now the "hunt"
begins....
Accuphase uses them like their $28K flagship DC-1000 and their other models. Chord (Mojo, Hugo, esp. Dave) uses them too so...
Practically don't care...for me. important is the "taste of the pudding".
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sajunky
Headphoneus Supremus
And all of them Delta-Sigma.Now the "hunt"
Accuphase uses them like their $28K flagship DC-1000 and their other models. Chord (Mojo, Hugo, esp. Dave) uses them too so...
m-i-c-k-e-y
Headphoneus Supremus
For R2R, Soekris uses them, Here's their current flagship DAC2541 (TI opa1656 for output buffer, converting SE to Balanced), remember.
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That’s a great opampFor R2R, Soekris uses them..Here's their current flagship DAC2541 (TI opa1656 for output buffer, converting SE to Balanced)
I put 1656 in a Aiyima a07 amp currently on loan to @BShaw who is refusing to listen to it!
Also have them in a Geshelli J2 dac
BShaw
1000+ Head-Fier
Actually got $30 for it on Craigslist last Thursday. I kept the opampsThat’s a great opamp
I put 1656 in a Aiyima a07 amp currently on loan to @BShaw who is refusing to listen to it!
Also have them in a Geshelli J2 dac
sajunky
Headphoneus Supremus
Veteran in a discrete R2R design. While many OEMs have licenced Soekris PCBoards, it is not really audiophile grade by today standards. SMPS for power supply...For R2R, Soekris uses them..Here's their current flagship DAC2541 (TI opa1656 for output buffer, converting SE to Balanced)
Soekris started lose customers since Denafrips Ares was released. Cheaper and better. In defense of 2541, it is oversampling DAC, so sound is already profiled. Easier for opamps. Soekris offered in the past special NOS firmware, but gave up, as with this hardware results were not convincing.
I wonder, why so heavily advertised opamp-less discrete amplification suddenly became irrelevant?
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rodthebod
100+ Head-Fier
I've come back to opamp controversy with May envy!
It's only a couple of days till June so things should settle.
So here's the detail, so there is no doubt that the R26 does utilise pairs of op-amps in the audio path, the ladder DAC's use these, one per ladder (dual version L&R channel) TI OP1678!
The audio output paths use a pair of TI 01642A but these are in series, which is probably a dual stage process doubling up on the op-amps, as used on many DACs (TDA1541A)
But why is the ladder DAC stage using a dual op-amp?
It's only a couple of days till June so things should settle.
So here's the detail, so there is no doubt that the R26 does utilise pairs of op-amps in the audio path, the ladder DAC's use these, one per ladder (dual version L&R channel) TI OP1678!
The audio output paths use a pair of TI 01642A but these are in series, which is probably a dual stage process doubling up on the op-amps, as used on many DACs (TDA1541A)
But why is the ladder DAC stage using a dual op-amp?
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