[rb2013]

  ok, battery wins. it's like i have vinyl going. turned on the table, and pretended i was listening to a record. it was convincing.

Nice!
 

  hancock 'thrust' reissue 180g vinyl...bit perfect wav file. 'actual proof', a total workout w/herbie, michael clark and paul jackson. digging the wav...

Have to get that one.  I buy these 200g and 180g then diigitalize them at 32 bit 176K - sound awesome from the music server.
 
But sometimes  - just love to spin the real thing - a ritual like thing

 

[m0reilly]

after a/b'ing the psu and battery, i still come back to the battery (hydra z on dac60). maybe after the last of the dac60 caps replaced finally burn in i may notice an edge going to the psu, but that's what i'm not liking re the psu: an 'edginess' on everything, bass is big but somewhat loose. cymbals seem to have an unnatural sibilance...

 

[rb2013]

Today I was doing my usual once a month Barnes ritual -espresso and a half dozen newest Audio magazines - came on this:
 
Congrates to Monarchy for the Absolute Sound 2015 Golden Ear Award - this what Dick Olsher had to say about the NM24 (based on the Lite DAC60)
 

The NM24 teaches us three important lessons regarding digital-to-analog converter design.  First, there's still plenty of magic left in Burr-Brown's 24-bit/96kHz PCM1704 chip, the world's most sophisticated R2R DAC chip, which Texas Instruments came close to discontinuing in 2012.  Second, a tube buffer is sonically superior to an op-amp buffer, as can easily be ascertained by auditioning both built-in buffers: an AD811 video op-amp and a 6922 triode-based SRPP.  Third, it is much easier (i.e., less costly) to design  a good sounding DAC using an R2R chip than it is with the currently ubiquitous delta-sigma type.  There are only two digital inputs (Toslink and coax), so you'll need a good external asynchronous USB link for computer audio.  As compensation, you can use the line-level pre-amp outputs as a headphone amplifier via a suitable adapter cable.  The sound is exceedingly analog-like, as the NM24 avoids the halo of brightness that permeates the harmonic textures of so many delta-sigma based DACs.  You'll have to look in the neighborhood of $5k to exceed it's performance. (Review forthcoming).

The NM24:


 
 
Lite DAC60:

 

 

[m0reilly]

saw this awhile back. like they want $2000 $1600 or sumit?

 

[rb2013]

saw this awhile back. like they want $2000 $1600 or sumit?

Our modded DAC60's are way ahead of the NM24, as you can see most of the caps are stock, couplers $20 MKP red boxes.

 

[m0reilly]

yep

 

[rb2013]

Some technical info on modding the DAC60 from a dedicated modders:
 
First why the Hammond Choke vs the resistor in the PS:

I replaced the CRC resistor with the Hammond 159P.  This also was a very good change sonically.  It really reduces noise in the power supply and makes it react a lot quicker, based on PSUD II simulations.  Listening confirms that.  I think the stock CRC electrolytic based power supply is overdamped and sluggish sounding.  Ripple goes from 86 mV to 1.3 mV which is almost two orders of magitude lower. 

 

I'd get the I/V resistor as low as possible.  The lower it gets the better the thing sounds.  Many of us have too much gain in our system anyway.  Particularly with those folks with active preamps.   I took out the stock metal film (I think) resistor and replaced it with a 15 ohm Mills.  With the Lite Dac 60, you probably won't be able to go that low, but 30-50 ohms will definitely help.  I put in little jumpers made out of high quality wire in place of the resistors, so I could clip in different brands and values. 

 I like the idea of pulling out the analog filter.  I'm going to try that next.  Lukasz (at www.lampizator.eu) doesn't use an analog filter on his SRPP output stages.  

In my opinion the big win with swapping capacitors in the B+ is getting rid of poor sounding electrolytics.  So going to Jensens perhaps won't help much.  I replaced the final B+ cap with a 70 uF Diy Hi Fi Supply Obbligato Oil Cap and a 39 uF 250v (I think) Solen film cap.  The 70 uF oil cap is huge but it does just fit.  Now this is a good improvement.  Too bad there isn't room in the chassis for another 70 uF Obbligato as the first B+ cap.

I think changing the plate and cathode resistors should be considered mandatory.  An amperex 6DJ8 is only rated to 15 mA,  the DAC-60 is set to 20 mA bias.   A 6922 is borderline as they are rated 20 mA max.  The 330 ohms gives a 6 mA bias.
The 330 ohms is probably being too conservative (I want my tubes to last a while.)  You could possibly get better sound with 200 ohms,  which is a 10 mA bias.

  On the spoiler the DF1704 digital OS filter is set to slow roll-off mode. On the stock DAC-60 it is brickwalled.

Caution this mod is not for the faint of heart.  You need a good soldering iron with a .5 mm bevell tip.  Set it for 600F or so.  Then with a pair of sharp needle point tweezers you can lift pin 27 while heating the pad.   You need bifocals and a LED headlamp to pull this off.  Then solder a wire from the lifted pin to a +5V.  There is an inductor right by the DF1704 that supplies +5V.  Notice I don't like giving component #'s because I believe it is very possible Lite changes the silkscreen.

The good news is that the draw on the tubes is just over 12 mA which is fine for 6922's but pushing it for 6dj8's. I played with the circuitry and it seems like eliminating the 2nd cap in the filter and replacing the first one with a .047u along with swapping the 220r for a 130r in the I/V goes a long way in giving a nice fr curve. This drops the output by about 4.5 db; should be O.K as when compared to several other dacs the output is about 3-4 db hotter. 

  I wanted to post my final mod that has left me not wanting to change anything else.  First I tried the Grounded-Cathode / Cathode follower mod.  Very clear and detailed and measured better than most any SS DAC.  However it sounded too much like SS.   So on a whim after putting the SRPP back I decided to hook the output cap to the plate of the bottom tube (instead of the cathode of the top tube.)

This increases the output impedance to 3.5 kOhms,  high - but fine for amps with 50 kOhm or higher input impedance.

This mod makes the DAC-60 have the same configuration as the first stage of the Aikido.  It is single ended not push pull (like the SRPP.)  The sound is very natural and full of life.  I used 200 ohms for the cathode/plate resistors.

Here is the parts list:

 

Caddock resistors 100 ohm  -  445-1986-1-ND

MKP Film Cap 0.015 uF  -  BC2140-ND

MKP Film Cap 0.1 uF  -  BC2054-ND

TDK Shielded Inductor - 445-1986-1-ND

Silmic Cathode 1000 uF Bypass Caps -  604-1059-ND

330 ohm 1/4 W resistors R6,R10, R9,R12
 
I replaced the output caps with 5 uF paper-in-oils.  I also have a choke to replace the CRC resistor but I am on the fence as to wether I should install it.  It would be before the mofset so I am not sure it would help,  also I know that if the choke isn't of the correct value it could screw up the B+ and add ripple.  I have seen reports where the choke is a big improvement though.
 

The resisters in question are R9 & R10, (on the outsides of the tubes), R5 & R7, (in front of the tubes), and R6 & R12, (between the tubes).
 
R10, R12, R6 & R9 your replacing with 330 ohm. R10 & R12 get the bypass caps. R5 & R7 get replaced with 100 ohms.
 
Make sure you bleed the B+ caps before touching anything
 

 

[rb2013]

Had to repost some things from a different thread on modding the DAC60:
posted by b0bb Quote:

Have you looked at replacing the 3-terminal voltage regulators with stuff from Belleson or Sparkos
 
http://www.belleson.com/
http://sparkoslabs.com/discrete-voltage-regulators/
 
Another suggestion would be to twist the wires coming out of the Big Hammond Choke and the R-core transformers, this gets rid of the stray 60Hz field and you will get a much blacker background.
 
The 60Hz stuff will blow thru everything except mu-metal or permalloy shields.
 

Reply rb2013:

Yes!  That and the critical resistors in the I/V stage and around the PCM1704UK's - looking at these Vishays: either the VTA Foils or the VAR Z Foils. I bet some of these stock ones are out of spec.
 
 
I see that Monarchy replaced the R-Cores with toroidal - what do you think of that?
 
Thanks for the suggestion on the wire twist will get that done on the next mod opening.  As always your knowledge is greatly appreciated!
 
This thing is sounding so good - it's hard for me to believe my ears.  The rich natural tone is breath taking - being fed by the Breeze Audio right now.  Best my office system has ever sounded.  Listening to Hyden Piano Sonatas - Jean-Efflam Bavouzet - the solo piano is hanging in space with absolutely perfect pitch and weight.  Smooth, musical - tone just spot on natural and creamy. 
 

Reply from b0bb:

  Those are the TX2575 VAR Audio  Z-Foils.
Texas Components can make them for you for about $10-$15, any value up to about 300kOhm, S-foils if >300k that at 2.5X the cost.
(Z-Foils are preferred to S-Foils for audio)
Call or email them for the ordering info.
http://www.texascomponents.com
 
I use them in the I/V converter on one of my DACs

 
Lite produces one of the best R-Cores coming out of China, I suggest keeping it.
 
Monarchy changed out the transformers for bigger ones to power the additional buffer stage.

   Wow those Bellson and Sparko Labs Bridge Recs are expensive!  Yikes $60-$80 each and the DAC60 needs 8 total.  Which ones would you say are the critical two?
 
 

 
Belleson has lower current versions (225mA) those are about $40 each, use these and not the highpowered 2A ones ($80)
 
The critical ones are the analog side of the DAC, the schematic it too rough for me to give you a clear idea
Just follow the trace on Pin19 (ref DC), Pin17 (Servo DC), Pins 15+16 (Analog ground) , Pin12 (BPO DC)
 
The DC reference is the most crtical so you will need 1 or 2 of those if there is a regulator there.
 
 
The digital ±5V supply pins are (pins 4,6,20,11)
For the digital side take a look at the RF LDO boards that DIYINHK  (LT3042, TPS7A4700) and Tekdevice (TPS7A4700) sell
These are $20-$40 each
 
Misc items like regulators for the tube heaters can be ignored.

 

 
Question form rb2013 to b0bb:

@ b0bb - just a quick question  - i'm looking to drop the impedence of the IV resistor as recommended by some other modders.  Say to 50-60 ohms.
 
Those would be the resistors in the front of the tubes or to the side?
 

 
Here was his recommendation:

I'd get the I/V resistor as low as possible.  The lower it gets the better the thing sounds.  Many of us have too much gain in our system anyway.  Particularly with those folks with active preamps.   I took out the stock metal film (I think) resistor and replaced it with a 15 ohm Mills.  With the Lite Dac 60, you probably won't be able to go that low, but 30-50 ohms will definitely help.  I put in little jumpers made out of high quality wire in place of the resistors, so I could clip in different brands and values.

So those would be the R7 and R5 - seems like going from 220ohms to say 60ohms would be quite a drop.  Or is he referring to the R9,R10, R12, R6 from 100ohms to 60ohms. 
 
I have plenty of gain from the DAC60 and would be looking to not be stressing the tubes as much.
 
He also commented:

I just read much of the latest reponses on this thread yet, just having discovered it again, but I've thought I'd comment since I've made some mods to my Lite Dac and am very pleased with them.  I have a Lite Dac 50, which is the PCM63 version.  The stock circuit is mostly identical to the Lite Dac 60.  It uses a 110 ohm i/v resistor because the PCM63 puts out twice the current, has an LCLR analog filter instead of LCLC, but in almost all other respects it is the same. 

So it seems it is the 220R (110 double) he is referring to.
 
Another modder mentions these I/V resistors as well:

The good news is that the draw on the tubes is just over 12 mA which is fine for 6922's but pushing it for 6dj8's. I played with the circuitry and it seems like eliminating the 2nd cap in the filter and replacing the first one with a .047u along with swapping the 220r for a 130r in the I/V goes a long way in giving a nice fr curve. This drops the output by about 4.5 db; should be O.K as when compared to several other dacs the output is about 3-4 db hotter. 

 
So I may replace the R7 and R5 with 130ohm or lower Vishays
 

Reply from b0bb:

R5/R7 are the I/V resistors if I am reading the rough schematic correctly
 
The 1704 puts out ±1.2mA (2.4mA peak to peak), the stock arrangement (220R) gives you ±264mV if you drop it to 60ohms the output drops to ±72mV, you might start to edge up against the noise floor of the tubes if they are noisy.
 
(R9/R12) (R6/R10) sets the SRPP gain
You can calculate the gain here: http://www.mh-audio.nl/tubecalculator.asp
Assuming a 6DJ8 (mu=33 Ri=2500ohm) gives an unbypassed gain of 16.20.
 
The pair of resistors are the red boxed ones in the schematic extract below.

 
 
The modded output of the DAC-60 is  ±1.2V, this is still adequate for driving stuff
I agree with the previous assessments the the DAC-60 has too much gain, ±4.8V in the stock case (Duh!)
 
±1.2V is the full scale value, you might find this is too low for classical music, you have the option of adjusting the I/V resistor or re-dimensioning the gain of the SRPP.
 
 
Feel free to experiment, suggest you start with regular resistors first decide on the final value and get Texas Components to make the final value in Z-Foils for you
 

Great stuff - awesome to have a knowledgeable and helpful chap like b0bb on this forum  - thanks again!

 

[m0reilly]

all i can says is that my modded dac60, in the last few days, has gained a level of detail and smoothness i have ever had the pleasure of hearing from any reproduction audio source, save a big master analog studio tape. on board for the r5/7 resistor mods

 

[rb2013]

  all i can says is that my modded dac60, in the last few days, has gained a level of detail and smoothness i have ever had the pleasure of hearing from any reproduction audio source, save a big master analog studio tape. on board for the r5/7 resistor mods

Great to hear you're liking it - I wanted mod to be posted here for Ref.
 
I'll do it too.

 

[Thenewguy007]

Looks like this is the only active thread for the DAC 60 available.
 
I'm no good at soldering & feel I would mess something up if I did.  The extent of my modding would be switching something that can be plugged in or unplugged.
 
If I did buy this & did not mod, how would it stack up against the higher priced R2R DACs?
 
 
 
I mean for sound quality, what do these compete with? $1,000+ R2R DAC? $2,000 sigma delta DAC?
Or more to its' price point, give or take a few hundred?

 

[DeLuX]

Looks like this is the only active thread for the DAC 60 available.

I'm no good at soldering & feel I would mess something up if I did.  The extent of my modding would be switching something that can be plugged in or unplugged.

If I did buy this & did not mods, how would it stack up against the higher priced R2R DACs?


I mean for sound quality, what do these compete with? $1,000+ R2R DAC? $2,000 sigma delta DAC?
Or more to its' price point, give or take a few hundred?

In allso wondering this... I think I would mange rolling some tubes but that's about it. Would the DAC-60 be worth getting if that's all I put into it? Not really interested in what value you'd put on it, just your input on the quality of sound

 

[kenman345]

I was actually wondering about the Monarchy's SS DAC part. What would be involved with getting a Lite-DAC 60 to not us a tube?

 

[m0reilly]

new caps have finally kicked down...new clock on the way but really the dac sounds very good atm. the mods so far are not too difficult (the ones i have done), it's being patient during the process more than anything. ken, if you haven't, i think you might want to hear the dac60 tube analog out first...

 

[kenman345]

  new caps have finally kicked down...new clock on the way but really the dac sounds very good atm. the mods so far are not too difficult (the ones i have done), it's being patient during the process more than anything. ken, if you haven't, i think you might want to hear the dac60 tube analog out first...

I am not saying i hate Tube buffered outputs. I love them actually. I had a Paradisea for a while and it was magical. My fear is the noise floor given my headphones are rated at 32 Ohms.....so the noise floor beig raised any is always an issue I fear about unheard items in my setup.