Yes, a turbomod & op amp changes to a DAC1

Posted by John C. - Aussie (A) on May 4, 2005 at 22:24:46

In Reply to: DAC1 mods posted by Jon L on May 4, 2005 at 21:27:32:

All the mods as shown below have been implemented.

I'm reconsidering about the Audiocm Clock III and might have it installed also.

Here is what Steve emailed me about the pros & cons of the DAC1:

As for the Superclock, this is definitely a good idea. The asynchronous upsampler reclocks the data with this clock and it is currently a $2 can-oscillator. Not good jitter specs compared to a Superclock.

The design of the DAC-1 has several good things about it and some bad ones. First the good things:

1) power supply is decent - transformer
2) Capacitor locations are reasonable
3) Current flow in the board for both power and signal is not bad due to the unbroken ground-plane
4) Chip selection for upsampler and DAC are good
5) high-quality board

Bad things:
1) layout is not optimum - some long traces
2) regulators locations are not optimum
3) too many op-amps - increases noise.
4) Input pulse transformer is grounded - can cause hum
5) uses dual op-amps - not as good as singles

And about the mods outlined below -

"Your unit is breaking-in nicely. I have been using it a lot since it is now my best-sounding DAC. BTW- a review from Mad Dog will be posted soon on Positive-feedback.com of my reference P-3A DAC. It will say basically that only the Dodson 218 beats it. I believe its possible that the modded Benchmark may actually beat the 218....."

WHAT HAS BEEN DONE:

Benchmark DAC-1 Turbomod
The Benchmark DAC-1 is an attractive DAC for several reasons: It has balanced outputs, two active volume controls, a headphone amp, and it sounds great right out of the box. This Turbomod improves several areas. It is AC-coupled to eliminate DC-offset, so we make it DC-coupled and tune-out the DC offset.
Most of the other changes improve power delivery and power supply. The op-amps deliver the best HF extension and clarity that we have ever heard in a DAC, so we know why the designer selected these. However, the same op-amps have difficulty achieving the "weight" of the performance. Our power delivery changes make a significant improvement in this area, but we offer an upgraded op-amp as an option. The input pulse transformer is a decent one, but it is grounded, which can cause low-level hum in some systems. We also offer an upgraded transformer, ungrounded, as an option. We recommend using the "calibrated" volume controls if possible. If you must use the volume knob on the front panel, we can mod the op-amps and capacitors associated with this for an additional charge.

A Benchmark DAC-1 with Turbomod and Op-amp replacement actually outperforms our reference, the P-3A, when in balanced mode. The most clear and holographic soundstage we have ever heard from a DAC.

Turbomod details:

Two bridge rectifiers replaced with HEXFRED's
Replace regulated voltage filter caps
Improve power delivery to DAC and upsampler chips
Improve power delivery to 10 op-amps - Black Gates and HF caps
Upgrade DAC filtering
Replace all voltage regulators.
Eliminate AC-coupling and tune-out DC offset
Improve digital input coupling

Pricing:
Turbomod - $1050

Option 1: Dual op-amp replacement - $300

Option 2: Pulse Transformer upgrade - $150

John

Interesting times

Link to Empirical Audio - go to COMPONENT MODS (Open in New Window)

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Follow Ups Full Thread

Topic - Old DACs vs. new ones? - J Corner 03:54:56 05/04/05 (38)

Re: Old DACs vs. new ones? - tiberian 19:31:04 05/04/05 (0)

The latest batch are dramatically better in my experience - John C. - Aussie 18:23:04 05/04/05 (12)

DAC1 mods - Jon L 21:27:32 05/04/05 (10)

Re: DAC1 mods - Todd Krieger 12:59:57 05/05/05 (6)

Then it would cease to be a Benchmark DAC1 but...... - rfbrw 12:13:39 05/08/05 (4)

I doubt he'd wanna double filter - Monkey Bones 12:53:32 05/08/05 (3)

Re: I doubt he'd wanna double filter - rfbrw 02:24:09 05/09/05 (2)

round and round - Monkey Bones 09:10:59 05/09/05 (1)

Re: Context,context,context. - rfbrw 19:23:53 05/09/05 (0)

Why don't you do it? - Jon L 14:33:35 05/05/05 (0)

Yes, a turbomod & op amp changes to a DAC1 - John C. - Aussie 22:24:46 05/04/05 (2)

humm . . . - Bruce from DC 12:36:21 05/05/05 (1)

Re: humm . . . - Terry Demol 06:52:48 05/08/05 (0)

For those kinds of bucks, I certainly hope so. (nt) - Travis 18:33:11 05/04/05 (0)

Re: Old DACs vs. new ones? - NickWay 09:49:14 05/04/05 (0)

Re: Old DACs vs. new ones? - elektron 08:54:54 05/04/05 (0)

I've been very happy with AudioNote DACs - GliderGuider 05:08:19 05/04/05 (0)

forget bencmark dac1 - juanitox 04:14:29 05/04/05 (20)

Want to warm-up a too clinical Bencmark dac1? - beppe61 01:01:38 05/05/05 (6)

Re: Want to warm-up a too clinical Bencmark dac1? - Lynn 06:55:30 05/05/05 (5)

Re: Want to warm-up a too clinical Bencmark dac1? - beppe61 02:02:51 05/06/05 (2)

Interesting... - Lynn 21:01:24 05/06/05 (1)

Re: Interesting... - beppe61 04:33:47 05/07/05 (0)

Re: Want to warm-up a too clinical Bencmark dac1? - Kenn 17:29:45 05/05/05 (1)

Re: Want to warm-up a too clinical Bencmark dac1? - beppe61 02:12:33 05/06/05 (0)

disagree. nt. - Lynn 21:05:13 05/04/05 (0)

Also disagree - why be so dismissive? - John C. - Aussie 19:06:08 05/04/05 (0)

Forget it, indeed. - Travis 18:30:00 05/04/05 (0)

Re: forget bencmark dac1 - BTan 16:38:54 05/04/05 (0)

Disagree #3 â€“ - saltyflies 14:21:07 05/04/05 (3)

no misunderstanding... - juanitox 16:47:53 05/04/05 (2)

agreed, no one size fits all - saltyflies 17:27:23 05/04/05 (1)

Yeah, and it's $8,000 - BadgerDMS 11:38:42 05/05/05 (0)

Disagree2 - Mr Underhill 13:28:29 05/04/05 (0)

Re: forget bencmark dac1 - philou 10:05:44 05/04/05 (0)

Agree - kjg 08:32:06 05/04/05 (0)

Disagree - Ned 05:47:33 05/04/05 (1)

Re: Disagree - juanitox 09:42:43 05/04/05 (0)

Follow Ups

Yes, a turbomod & op amp changes to a DAC1 - John C. - Aussie 22:24:46 05/04/05 (2)

humm . . . - Bruce from DC 12:36:21 05/05/05 (1)

Re: humm . . . - Terry Demol 06:52:48 05/08/05 (0)

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