R-2R Audio Note DAC 4.1 DIY and mods

Thank you. Fun to read. Could be a possibility when I go for a DAC upgrade.

Astrostar - As the owner of an AN 1.1 myself I love the article. Lots of food for thought in the article. The one question I have: My AN does not have a USB input. Did yours have a USB input or did you add one? If the former do you have any sense how complicated that would be?

Hi there about two years ago I decided to create a decent USB interface for my Dac 2.1 (identical digital board as yours). It is possible to do. I used an Xmos based converter to take USB to I2S and then designed and built a new digital board that allowed the necessary interface to the AD1865, every other part of the board was pure Audio Note design. It sounded Fab, the Ad1865 will easily do 192kHz, but obviously sticks at 18bit.

I foolishly then decided to rebuild the whole thing and it is now in the things to do list.

A much easier route would be to use a good USB to SPDIF converter. The reason I choose against that is the CS8412 chip which is on the digital board will not handle higher than 96kHz.

Looking at your digital power supply that might bear improvement, rumour has it the earlier kits had a better design using a separate transformer but remember most of the digital board is in fact digital/analogue PSUs and they are very good, so not sure how much more there is to be had.

I am deeply envious of the output stage you have, and the I/V transformers.......

My modded Audio Note was still the finest DAC I have had - I can't imagine what it would have sounded like with your output stage!

Hello,

Very interesting story, thank you! Have two questions:

May you advice where to buy this custom made Audio Note aluminium faceplate?

How you chose Delund capacitors, its probably most expensive capacitors in the word?

Astrostar59,

I started with the same 4.1 LE kit a few years ago. I've done similar mods, including AN 496 IV transformers, 2 watt tants, AN Super HiB output transformers, and Jensen silver foil caps in the paper tube. I also added Black Gate caps where I could. I am extremely pleased with the results. I also have Stax 009s and use them almost daily. I couldn't be happier.

Astrostar59,

 

I started with the same 4.1 LE kit a few years ago. I've done similar mods, including AN 496 IV transformers, 2 watt tants, AN Super HiB output transformers, and Jensen silver foil caps in the paper tube. I also added Black Gate caps where I could. I am extremely pleased with the results. I also have Stax 009s and use them almost daily. I couldn't be happier.

You made very interesting job, and have good experience now. I would like upgrade my old AN DAC 2.1, what I just bought. 4.1 LE kit has output transformers. Did you feel big difference in sound, when you put AN super Hib ? I need to make decision what components to buy. AN has different levels of components and price level is changing more 10 times, so is it worth to put?

You made very interesting job, and have good experience now. I would like upgrade my old AN DAC 2.1, what I just bought. 4.1 LE kit has output transformers. Did you feel big difference in sound, when you put AN super Hib ? I need to make decision what components to buy. AN has different levels of components and price level is changing more 10 times, so is it worth to put?

sigitask,

At the time I bought the kit, it came with AN M4 I-E core transformers. I checked this morning and the transformers I upgraded to are the Ultra Hi-B with copper primary and secondary windings, not the Super that I had originally written. So I moved 3 notches up the range. It took a few weeks for them to run in but once they did I noticed a large difference in dynamics, which is what I was expecting. Originally I planned to go with the Ultra HiB that has silver primary and secondary windings, so 2 notches further up the range, but my tech who is very experienced with AN transformers told me that the differences I'd notice would likely be small. So we spent the difference on the TRANS-496 I/V transformers. I am very happy with the transformer upgrades and I definitely consider them to be worthwhile. I hope this helps.

Hi,

Thanks much for posting your AN DAC journey. Very inspirational!

There's just not a lot of AN DAC modding discussion on the web.

I'm hoping to get some advice after installing a Sowter 1465 IT Tranny.

The output is much weaker and I'm not sure which resistors to change.

Hello

The I/V should be 1:1 ratio. Is the Sowter a different ratio?

In the Audio Note UK DAC line board it is loaded as 680R in and on the digital board 680R out (near the chip).

In the kits is is 280R at the chip, and 3000R at R1 and R11 on the line board (so loaded). I think your line board is the kit board? I would ring Sowter and ask the loading required at both input and output. Or try changing the 3K at R1 and R11 to 680R.

On the AN UK DACs they also use a small cap at the output and inout of 680pFs. See the pics on the web of the DAC 4 or 5. My AN UK DAC 5 has this as well.

If still stuck, try asking Andy Grove at AN UK, he will know, as they used too use Sowter way back. Brian will not know I don't think, as I went through this stage with ANK, though I used the AN 496 I/Vs.

Good luck.

Thanks for your thoughtful answer.

Your hunch that is a ANK board is correct.

I put in a request to Sowter for input and output loading requirements as you suggested. 

What Sowter lacks in expedience they make up for in quality when it comes to support. So, hopefully I'll hear from them soon.

Sowter has section titled "How to calculate I/V resister" on this spec sheet.

A couple of quotes from this source- which I'm not sure is relevant or not?? -  "Provides current to voltage conversion with gain to achieve at least a line level signal (0 dBu 0.775V) depending on the I/V resistor used."   " Configuration: Primary coils in parallel. Seconday coils in parallel. Ratio = 1:5  For line level out use 3.3K Ohms secondary load. For increased output level increase load in proportion."

I hate to be such a plebe but when it comes to digital schematics or transformer math, I'm a bit clueless.

I plan to tackle your power supply next, but need to get the right resister in here first.

Thanks again for sharing your experience and taking the time to help. You're a Prince!

FYI- more pics.

I have a very old AN DAC4 which I am still using and find it hard to replace because of its excellent SQ.  However as it was bought so long ago and using PCM63Pk chips, I thought it might be possible to upgrade the digital board and some vital components such as transformers and capacitors.

I attach some images of the interior of the DAC and hope to get some suggestions of how to go about upgrading this DAC.

"I have a very old AN DAC4 which I am still using and find it hard to replace because of its excellent SQ.  However as it was bought so long ago and using PCM63Pk chips, I thought it might be possible to upgrade the digital board and some vital components such as transformers and capacitors.

I attach some images of the interior of the DAC and hope to get some suggestions of how to go about upgrading this DAC"

My guess is that upgrading your DAC wouldn't make financial sense. But maybe upgrading a key cap or two might be worthwhile. I can't see your caps but it looks like you have lots of BlackGates... which is a very good thing.

Thanks for the reply ogie.  I guess the worthy upgrade maybe the digital board (to R-2R) if it is possible. Also the output trans if it will make a reasonable improvement.  I have written to AN Kit to ask them for their opinion.

4 minutes ago, michaeltay5871 said:

Thanks for the reply ogie.  I guess the worthy upgrade maybe the digital board (to R-2R) if it is possible. Also the output trans if it will make a reasonable improvement.  I have written to AN Kit to ask them for their opinion.

I would consider building an Audio Note Kit. That is what I did and it had a great sound. It also has lots of further tweaking and upgrading that you could do to it later i.e. keep off the buying and selling DAC saga. That is what I did.

Your DAC4 is very old BUT original. I would sell it on AGon or HifiWigwam as intact. I believe your DAC is NOT non oversampling, that came later with the AD1865 chip. And it has filtering which Peter took out around 2006. I can see the filter caps on the digital board. And they improved the I/V conversion with transformers, then added output transformers. It really takes the sound you like right now, and injects it with everything you want, just more of all the good stuff. Funny, so many manufacturers have following (nicked) many of Peter's ideas IMO.

The Audio Note DACs are oddball for sure, but as I have found, they beat the pants of so many 'hi-end' DACs I have demoed over the years. I recently demoed the CH Precision C1 (R-2R) which is 21K and it beat that as well, also the Esoteric K-01, the Naim 555, it goes on. You don't get fancy casework, or DSD (who wants that?) but what you do get is Redbook to die for, a superb smooth sound and fatigue free real music. Reminds me of my vinyl rig. If you want 'hifi' sound look elsewhere.....

Talk to Brian. I know him well, he will give you more advice and sort you out. The 4.1 Kit is the one I would go for.

On 4/17/2017 at 4:46 PM, ogie said:

Hi,

Thanks much for posting your AN DAC journey. Very inspirational!

 

There's just not a lot of AN DAC modding discussion on the web.

 

I'm hoping to get some advice after installing a Sowter 1465 IT Tranny.

 

The output is much weaker and I'm not sure which resistors to change.

 

 

 

Hey,

I've been checking every now and then this particular topic because I'd like to see if I could a grip on blueixus with some detailed questioning on the ad1865 board, I'm also getting a waveIO and I'd love to try I2s out.

For your board, it's the dac 3.1 board, the value you have to change is R11 which is a 3k3 resistor. It should have a color code like orange orange black brown brown. The resistors on your dacs' side (the other side of the trafo) are the tantalum resistors. What will you be doing with your old transformers?

As for Michael, the PCM63PK should be a very good dac chip, I think you can better change the whole dac instead of fiddling around with that. If you're really interested in trying to upgrade the sound, my bet would be at the output capacitors. These are already very fine paper in oil capacitors from Jensen (rebranded as AN or Angelica). You need to put some money into that to go past it. My guts say that Audyn Copper Max should be a fantastic cap, but in the DIY the stars in the show are Duelund and V-cap. The Obbligato Premium tin foil seems like one to try out as well.

@astrostar 

My guess would be that Andy took the digital filter out while Peter sat in a chair talking about it. When talking about nicking you could also look into the history about An UK and Kondo.. I mean no harm with that, and I do believe a lot of 'right' are in the AN material. 

I think the dac kit is not so great, or lets say quite away from what would be optimal. First see the cut corners with the utilized transformers. The earliest kit still has the TRANS-103, these all got replaced with hammond. It is also quite inconsistent with various material, fun hobby material but I would not touch go that route. Note that also the dacs from AN has gotten further development on their own, that doesn't mean that the DAC itself doesn't produce sound anymore, and that every step forward is one for the better.. You get it.

Don't pinch me down on details but, when the dac got developed there where two people on it, Peter van Willemswaard and Andy Grove. Andy Grove's design eventually got utilized but PvW modded and developed his own version. It's using shunt power supplies for the dac, has gotten all kinds of problems tackled AN UK isn't considering. I haven't listened to it, but it makes a damn lot of sense.

PS Michael,

There is also huge improvement to be made by replacing the resistors in your board. On this board everything used are Beyschlag metal film. The easiest road for improvement would be replacing them for Welwyn/ Mills resistors in PSU section (some already are wellwyn) and tantalum resistors in the output section. Perhaps the 330r on the cathode could be a carbon or metal film, but thats yours to try out and see for yourself.

On 4/17/2017 at 4:46 PM, ogie said:

Hi,

Thanks much for posting your AN DAC journey. Very inspirational!

 

There's just not a lot of AN DAC modding discussion on the web.

 

I'm hoping to get some advice after installing a Sowter 1465 IT Tranny.

 

The output is much weaker and I'm not sure which resistors to change.

 

 

 

Sorry for 3 posts in a row.. but I've rechecked it and R1 and R11 are definitely not the right value to begin with.

On this photo you can see that the resistors that should be having stripes of orange, are brown at yours.. Try and change them to the correct value.

Fellas... Thanks for the input.  I have resisters on order and will report back.

Also... I have been conversing w Sowter and they have question I'm not able to answer. Does anyone know:

"Do we yet know if you are using Iout or Vout.  Are you connecting  to Iout (pins 21/4) or Vout (pins 17/8)?"

Thanks- Doug

Ah this is something related to the DAC topology.

Since I've build that myself I can check the datasheet. As far as the KITS are concerned, you're using pin 21 and 4, so you're connecting to Lout. 

IF you want to be definitely sure, set your multimeter on 'beep mode' and measure from the 4th pin on the left on the left side of the DAC chip to the resistor at the side of it. The pins are numbered as followed: left side starts as 1 and goes to 12, bottom right starts with 13 and goes up to 24. If you don't understand this I'll try and add a picture to clarify.

Cheers

I was thinking about this. The Kits never used the Sowter I/Vs, but the UK DACs did way back. The loading on the kit DACs is very different to the UK DACs, as I spoke to Andy Grove about this very subject when I was doing my mods. The AN UK DAC has a 680R at the chip and 680R at the input to the line board, thus the I/V is balanced same load each end. The kits however have 330R at the chip and 3KR at the line board input. Thus the kit is 10 times the resistance at the input end on the line board. Quite possibly the kit I/Vs are very different, and this would explain your signal drop.

I fitted 680Rs both ends on my Kit DAC with the 496 I/V and it worked perfectly.

Below is Brian Sowter's comments along w an attachment:

Excellent!  We have established that you must be using the Iout terminal(s) Pins 21 and 4 for the L and R channels.  The DAC puts out +/- 1mA peak to peak.  This equates to an rms current of 0.71 mA.   Don’t worry about this point but generally is easier to work with volts and amps rms which is what you measure with a volt meter or ammeter.

We have been working with DAC’s for 20 years too and we recommend a step up transformer not a 1:1! We have sold literally hundreds of step-up transformers for DACs.   So the good news is that our type 1465 is the ”correct” transformer at least if you follow our recommendations.

Now for the choice of I/V resistor.  First you need to wire the 1465 with the primary windings in parallel and the secondary windings in parallel giving you a simple 1:5 transformer with a very high bandwidth.  Connect the primary between pin 21 (or 4) and ground with NO resistor in parallel. You then connect the I/V resistor across the SECONDARY of the transformer.  See attachment.

Second you need to decide what voltage out you need.  I suggest you go for 1.0V.

Now for the calculation:

0.71 mA (=0.00071 Amps) in the primary is 0.00071 / 5 = 0.000142 Amps from the secondary. 

By ohms law ( R=V/I remember?) the I/V resistor you need to get 1.0 V, R = 1 / 0.000142 = 7042 Ohms.   On our site we recommend 6.8K which is close enough.

Hope this helps

Best regards

Brian

sowter 1465 attachment.pdf

48 minutes ago, ogie said:

Below is Brian Sowter's comments along w an attachment:

Excellent!  We have established that you must be using the Iout terminal(s) Pins 21 and 4 for the L and R channels.  The DAC puts out +/- 1mA peak to peak.  This equates to an rms current of 0.71 mA.   Don’t worry about this point but generally is easier to work with volts and amps rms which is what you measure with a volt meter or ammeter.

We have been working with DAC’s for 20 years too and we recommend a step up transformer not a 1:1! We have sold literally hundreds of step-up transformers for DACs.   So the good news is that our type 1465 is the ”correct” transformer at least if you follow our recommendations.

Now for the choice of I/V resistor.  First you need to wire the 1465 with the primary windings in parallel and the secondary windings in parallel giving you a simple 1:5 transformer with a very high bandwidth.  Connect the primary between pin 21 (or 4) and ground with NO resistor in parallel. You then connect the I/V resistor across the SECONDARY of the transformer.  See attachment.

Second you need to decide what voltage out you need.  I suggest you go for 1.0V.

Now for the calculation:

0.71 mA (=0.00071 Amps) in the primary is 0.00071 / 5 = 0.000142 Amps from the secondary. 

By ohms law ( R=V/I remember?) the I/V resistor you need to get 1.0 V, R = 1 / 0.000142 = 7042 Ohms.   On our site we recommend 6.8K which is close enough.

Hope this helps

Best regards

 

Brian

 

 

 

sowter 1465 attachment.pdf

Cool stuff!

Good to know that its a family business. I am very unknown with the workings of electronic devices, all that I know I've 'learned on the fly'. I remember reading an essay about transformers by who I assume would be Brians' father, I only understood half of it.. but that was before I've hooked up a transformer. There is something about Sowter that very much appeals to me; typewriter style datasheets, stone-age website but 1000% intel! Something tells me that it takes a lot of extra money to get the AN equivalent of the Sowter, but that's all intuition.. 

Glad you got the correct resistor value. Get a nice 6K8 Shinkoh tantalum.. partsconnexion, hificollective and acoustic-dimension is still stocking these (they're great!). The places where the 6K8 have to go are R1 and R11 if we deal with the assumed 3.1 schematic.

That is a great response from Brian Sowter, I am planning on going this exact route shortly on my AN style Dac!

Hey Fellas,

I wanted to follow up on the Sowter install and let you know that after listening for a month or so - that I am very happy with the results.

I'll probably give it another month or so and then start thinking about upgrading the caps and possibly the power supply board. 

Thanks for the help..