A New Take on the Classic Pass Labs D1 with an ESS Dac

[qusp]

not yet no, you havent read the thread? owen is still working on the final PCB, though I gather its ready now, I dont know whether it has gone off to fab yet

[merlin el mago]

Thanks for the info, I am sorry, I see a photo with pcb & I supposed that will be available or will be a GB.

[qusp]

no problem, no the PCB you saw was a modified D1 IV stage I think. I also have this, but it requires some modification to work

[Calvin]

Hi,

tested the Borbely I/V (pasive resistor conversion + discrete OP-amp gain stage) against a JockoHomo-sructure (grounded Base, very similar to Owen´s stage but with active ccs and lower bias currents) and modified Hawksford structures. All of them sounded clearly better than OP-amp stages, but the Hawksford came last. The Borebely and the Jocko were nearly on par, with the Jocko beeing preferred more of the time. The Jocko remained unbeaten in the mid-highs while the Borbely showed more weight and slam in the bass.
The Jocko improved in the bass after careful tweaking of supply paths.
Still though the Jocko remained rather a conoisseur´s circuit, the Borbely rather the Wham-Bam-thank-You-Mam circuit.
I expect Owen´scircuit to be sonically at last on par with the Jocko, but with better measurement value.

jauu
Calvin

[merlin el mago]

Originally Posted by Calvin

Hi,

tested the Borbely I/V (pasive resistor conversion + discrete OP-amp gain stage) against a JockoHomo-sructure (grounded Base, very similar to Owen´s stage but with active ccs and lower bias currents) and modified Hawksford structures. All of them sounded clearly better than OP-amp stages, but the Hawksford came last. The Borebely and the Jocko were nearly on par, with the Jocko beeing preferred more of the time. The Jocko remained unbeaten in the mid-highs while the Borbely showed more weight and slam in the bass.
The Jocko improved in the bass after careful tweaking of supply paths.
Still though the Jocko remained rather a conoisseur´s circuit, the Borbely rather the Wham-Bam-thank-You-Mam circuit.
I expect Owen´scircuit to be sonically at last on par with the Jocko, but with better measurement value.

jauu
Calvin

Hi Calvin & thanks, could you post Jocko schematics?

[Calvin]

Hi,

there have been posted unnumerous incarnations of the Jocko here already. Some using bipolartransistors, some using MOSFETs, some using JFETs......I won´t add another one.

What became obvious was that the lower the parts count within the signal path/circuit the more authentical or pleasing it sounded. The drawback of this is usually inferior measurement values especially THD-wise. The highcurrent-highvoltage Jocko or Owens D1B1 (name them as You wish) seem to break the rule. Still though show Sims that if You add a simple active current source towards the negative rail in Owen´s schematic that the already low distortion values slightly decrease. It will be up to an listening evaluation though if this mod is worth beeing implemented.

jauu
Calvin

[merlin el mago]

Originally Posted by Calvin

Hi,

there have been posted unnumerous incarnations of the Jocko here already. Some using bipolartransistors, some using MOSFETs, some using JFETs......I won´t add another one.

What became obvious was that the lower the parts count within the signal path/circuit the more authentical or pleasing it sounded. The drawback of this is usually inferior measurement values especially THD-wise. The highcurrent-highvoltage Jocko or Owens D1B1 (name them as You wish) seem to break the rule. Still though show Sims that if You add a simple active current source towards the negative rail in Owen´s schematic that the already low distortion values slightly decrease. It will be up to an listening evaluation though if this mod is worth beeing implemented.

jauu
Calvin

Hi Calvin, if you won't want to do a public post could you send me a PM with your own schematic used.

Thanks in advance.
Felipe

[merlin el mago]

Originally Posted by Calvin

Hi,

there have been posted unnumerous incarnations of the Jocko here already. Some using bipolartransistors, some using MOSFETs, some using JFETs......I won´t add another one.

What became obvious was that the lower the parts count within the signal path/circuit the more authentical or pleasing it sounded. The drawback of this is usually inferior measurement values especially THD-wise. The highcurrent-highvoltage Jocko or Owens D1B1 (name them as You wish) seem to break the rule. Still though show Sims that if You add a simple active current source towards the negative rail in Owen´s schematic that the already low distortion values slightly decrease. It will be up to an listening evaluation though if this mod is worth beeing implemented.

jauu
Calvin

Hi Calvin, to know more things about your comparisons, please be so kind to let me know: are you using his own all fets discrete reg. for Erno Borbely I/V & about PSU are you using Borbely his own with chokes & 10.000uF 63V Jensen 4 poles caps?

[Calvin]

Hi,

I tried a own design, based on the Jocko using bipolar transistors and and more advanced current sources and dimensioned for the PCM1794A DAC working in Mono mode. Sound was absolutely great, size was tiny, but THD was worse than I liked it to be. It ran on 12V dual supplies. Probabely similar to Owen´s stage I assume there was not enough voltage overhead.
The Borbely was connected to a good SMPS, maybe some caps between, I don´t know any more. Because beeing of a fed-back-OPamp-topology and the sheer size of the PCB ruled out further investigations into the matter.

jauu
Calvin

[merlin el mago]

Hi,

Thanks for answer, now I understand your opinion.