NOS Burr-Brown PCM56 DAC with Tubes!!!

[L0rdGwyn]

I believe it sounds fantastic, actually I own cd player on double PCM56 chips and to my ear PCM56 "has cottton like softness" and such a "flow and musicality" maybe not last word in terms of resolution but who cares. Anyway your dac is impressive, 7 transformers (right?), tubes battery biased, simply wow, true hi-end stuff. I would like to se "jaw drop" of young, measurements oriented guys on ASR after A/B it to their best SINAD reference.... Sound quality is much more that that.

We are in agreement (of course or I would not have made such a DAC), controversial to say here though! Good measurements do not beget good sound IME, it is a tool that I do use as you can see. I want low distortion, low noise, good bandwidth, low output impedance, but it is not the last word if they are not perfect. Yes, seven transformers! One isolation, four power, two SUT.

 

[sonci99]

I often use a playstation 1, the model with rca out, when I just want to listen to some cds.
You can hear some kind distortion going through, but the punch and details are still good and music is smooth, no digital edge or fatigue.
I can listen to it all the day, cd after cd.
And when I change to a real cd player or dac, it makes ps1 sound like a tape deck, unfortunately or not, I still get back to it..
In the end we listen to the music, not gear, so if you don’t like the sound of a state of art device and have no money for room treatment or changing speakers, then good distortion helps..
btw, if you say that I cannot pick the ps1 double blind, that’s easy, just get one, it resolves only 14bit of audio, but they are the good bits..

 

[SIY]

The tube seems like it's similar to D3a?

 

[L0rdGwyn]

The tube seems like it's similar to D3a?

It's a tetrode but as a triode it has a lot of similarities to the D3a, however lower mu (33 vs. 77 for D3a) and lower plate resistance (1.2K vs. 1.9K for D3a). It is a close relative to another high gm Russian tetrode, the 6E5P.

 

[_thelaughingman]

Dang those some good like bitties on that chassis.

 

[Alexium]

I own cd player on double PCM56 chips

What's the model of your player? I also want to get a dual PCM56 CD player, but there are several grades of these chips - the lowest grade PCM56P-L being the cheapest on the used market, and the most common.

 

[Alexium]

The isolation transformer is a medical grade model from Triad Magnetics, VPM series. The little 12V and 15V toroidals are made by Talema, 7XXXX series. Digikey has some models, but they did not have the ones I needed, so I had to order from the UK through RS Components. The tube B+ / heater toroidal is made by Antek, they have a great selection, many of which have dual HV secondaries, very flexible.

Thank you for your kind and informative reply! I saved it for future reference And you have inspired me to try new things in audio.

Unfortunately, I'm not from the US. CanJam looks like a lot of fun! I know there are all kinds of conventions big and small for all kinds of hobbyists in the US (and I guess in Europe, too), which is truly awesome. I've never seen any events of that sort in my country.

 

[L0rdGwyn]

What's the model of your player? I also want to get a dual PCM56 CD player, but there are several grades of these chips - the lowest grade PCM56P-L being the cheapest on the used market, and the most common.

If you were to buy a player with a lower grade chip, the highest grade "K" chips can be bought online (eBay, for example) quite cheaply. From China, chips can be had for $6 USD each.

Thank you for your kind and informative reply! I saved it for future reference And you have inspired me to try new things in audio.

Unfortunately, I'm not from the US. CanJam looks like a lot of fun! I know there are all kinds of conventions big and small for all kinds of hobbyists in the US (and I guess in Europe, too), which is truly awesome. I've never seen any events of that sort in my country.

And you're welcome!

 

[L0rdGwyn]

There are a few other chips that can be dropped into this circuit without any changes: PCM61, AD1851, AD1861, and AD1860, something to try in the future.

 

[DHT 845]

What's the model of your player? I also want to get a dual PCM56 CD player, but there are several grades of these chips - the lowest grade PCM56P-L being the cheapest on the used market, and the most common.

actually a checked that it has 2x PCM61P (I remembered that sth lower than PCM63), it's denon DCD-895

 

[DHT 845]

2x PCM56 were used in denons: dcd-210, dcd-460, dcd-520, dcd-620, dcd-810, dcd-830, dcd-910, dcd-1130, dcd-1400, dcd-1500 mk2, dcd-1600, dcd-1700, dcd-3300

 

[Mentorron]

I believe it sounds fantastic, actually I own cd player on double PCM56 chips and to my ear PCM56 "has cottton like softness" and such a "flow and musicality" maybe not last word in terms of resolution but who cares. Anyway your dac is impressive, 7 transformers (right?), tubes battery biased, simply wow, true hi-end stuff. I would like to se "jaw drop" of young, measurements oriented guys on ASR after A/B it to their best SINAD reference.... Sound quality is much more that that.

I have two Sonys: one with dual PCM56Ps (I was advised these are single channel DACs, that's why Sony used two in this CDP-490 (c.1990) of mine in my garage system. It feeds Mission 760i speakers with a cheap ProLinear PLSUBMKII 100W powered sub I added recently to fill out the range between 65 and 30 Hz. My older Sony is a CDP-950 / Feb..1988 (aka a CDP-307ESD with one minor error reporting circuit missing). It has a single Philips TDA1541. I read somewhere on the Web that Sony did a better job of implementing the 1541 than Philips ! This is in my primary system feeding Martin-Logan original Aerius electrostatic hybrids. Have investigated upgrading to something newer, but nothing so far as engaged my passion in sound reproduction that doesn't cost about as much as a new car. And I don't have money to burn. These two players were bought at thrift stores. The 950 for $12.99 in 2010 and the 490 in Feb. 2021 for $15.99. The 490 replaced a Philips CD614 with dual TDA1543 DACs. It had a slightly "brighter" high end which annoyed me at times, so I prefer the BBs. I kept the Philips player as it has a CDM4-19, one of the best trackers made.

 

[Billy Budapest]

What do the AA cells do in your circuit?

 

[SIY]

What do the AA cells do in your circuit?

Bias the grid to set the operating point.

 

[L0rdGwyn]

What do the AA cells do in your circuit?

Yep, the AAs set the grid bias of the output tubes.

 

[alpha_logic]

I felt the same way about DACs for a long time - tried many different delta-sigma DACs, all sounded exactly the same to me. I was adamant all DACs sounded identical...I then had the chance to audition some NOS R2R type designs where the difference / improvement was undeniable, completely turned my DAC world upside down, and I'm glad it did, I am getting much better digital sound nowadays having bought into it. Just my experience, of course.

I took the opposite approach: I started, years ago on the assumption that R2R must be better, despite inferior measurements. But no matter what I tried - Borderpatrol, AudioGD, Denafrips and DYI based PCM1704/1541/1537 DACs - I never got what I was looking for, just less resolution, and more distortion.
What you built there though is a thing of beauty, and I'm glad it turned out to be what you're looking for, very well done!

 

[Alexium]

I took the opposite approach: I started, years ago on the assumption that R2R must be better, despite inferior measurements. But no matter what I tried - Borderpatrol, AudioGD, Denafrips and DYI based PCM1704/1541/1537 DACs - I never got what I was looking for, just less resolution, and more distortion.
What you built there though is a thing of beauty, and I'm glad it turned out to be what you're looking for, very well done!

So what's your current favorite DAC?

 

[alpha_logic]

So what's your current favorite DAC?

My current favorite is the SMSL D300.

 

[L0rdGwyn]

I took the opposite approach: I started, years ago on the assumption that R2R must be better, despite inferior measurements. But no matter what I tried - Borderpatrol, AudioGD, Denafrips and DYI based PCM1704/1541/1537 DACs - I never got what I was looking for, just less resolution, and more distortion.
What you built there though is a thing of beauty, and I'm glad it turned out to be what you're looking for, very well done!

Thanks!

I also have a Border Patrol, in storage lol I am not a fan, it sounds quite bad actually, fatiguing to listen to, really feels like a "it's R2R, and vintage, with a tube!" cash grab, the circuit is poor. I mentioned in another post, I have a second DAC based on the TDA1541A by a boutique Serbian company, the Audial S5. It is well-engineered within the confines of that chip and sounds great. BUT this PCM56 DAC sounds better, believe it or not. So I think vintage R2R can be done well, just depends on the design. I gathered a lot of information before this build from various DIY designers and incorporated what I felt was most sound from an engineering standpoint, the result was far beyond my expectations, subjectively speaking.

 

[Alexium]

I have no problem believing PCM56 sounds better than 1541A, it is a better DAC chip. And implementation is very important - more than the chip itself, I think.

P. S. I'm curious, have you tried adding negative feedback to your tube output stage? Or 6E6P does not have enough gain to support that?
And another noob question: what is the input transformer for? Is it just for 5x gain (assuming that's what 1:5 means)?