LITE DAC 60 & 72

Would appreciate comments & advice on these DAC.

1.   Is 72 an upgrade version of 60?
2.   What are the simplest steps to improve 72, such as tube replacement (which brand & designation), etc?
3.   I'm clumsy with a soldering iron and have eye-sight that is too old to do precise DIY work.

Many thanks to experience feverites who are kind and generous to help.

:wink:

I will have to DIY another set of cables first before I can connect the two pre-amps together. I don't want to pull the pair from the LP as it is hard to put them back in.

Will tell you about the results later.

CAT

It depend on your system, as some of the preamp need to turn to certain level then only balance or sound will come out then u need it to be at that level.


For normal case since the M7 is as buffer, u just turn it to a minimum (very low volume level, if u use 24 step attenuator then step 2 or 3 is sufficient, u can alwyas play around with it)

then the main control is by your pass lab....

just let me know any changes in sound.... better or worse....

If let me guess--> will have tube feel, better vocal, but bass reduce. then dynamic & and spacing may reduce very slightly.

My previous post gone again ....

Oh, I can do that? How should I set the Volume Switches?

1. Turn up the Volume of M7, use the Pass Labs volume as final control.
2. Turn the volume of M7 to medium, turn up the volume of Pass Labs.
3. Turn down the volume of M7 to minimum, turn the Pass Labs to Max.

Which one should I use? Seems "1" is a good choice.

Cat,

since you got both mz & passlab with you, can u try connect CDP --->M7-->passlab then to your VT60??

Meaning that M7 is used as a buffer, see whether it can have all the strength of passlab + the tube feeling of M7??

Oh, I can always use the M7 for female vocals and and Pass Labs for others ... ha..ha.. :wink:

I am thinking of getting a Fostex or alike for female vocals ... I have heard that it is not very expensive (small ones) but getting the wooden box (cabinet) is indeed a headache.

CAT

Agree.... M7 hardly obtain very good dynamic & high resolution....by changing the cap value can extent little bit on LF but i really like the way it present the vocal....

the only problem i had now is the LF hum which can hear from the woofer at ~15cm from the woofer....even though not obvious but i wish to reduce it to zero....

yes, it sound a little bit better with tube rectifying.....
However, the M7  circuit itselves still has limitation.

[quote:131f89743a="alfcat"]Accphoto,

What do you think? Do you think the M7 will sound better using tube rectifying?[/quote]

Dear Cat,

Accphoto is right it use selenium and u can't get it now.....

i myself like tube rectifier..... some like ss rectifier... so depend on your taste.... my 5687 initially is using ss rectifier but sound stage and imaging not good, space is narrow....

No harm to try tube rectifier...

Accphoto,

What do you think? Do you think the M7 will sound better using tube rectifying?

Original Marantz 7 use Selenium as rectifier. These type of material will generate toxic gas when blow up so basically it is no longer available. However, a lot of people insist that this is one of the factor for good sound.

WINDWSS,

One of my friends just told me that the original Marantz 7 uses Transistors as rectifying instead of Tubes ..... Any idea?

CAT

Dear WINDWSS,

Something like that ... maybe high grade MP3 player or recording pen. I don't have a Tape Recorder. Ah ... I forgot I got a "good" MD recorder.

You are right. I sold my ProAc 1SC clone this summer. I am now using the Castle Conway 3 floor standing. It is very nicely finished and gives out pretty good sound as well. Castle is the company that manufactures speaker housing for ProAc and other famous brands.

I have checked their wires and the crossovers. They use their own brand name internal wires .... and the caps are really HUGE compare with my previous speakers ....

CAT

Cat,

U mean u will use a tape to record down the playback? or just note down in paper on the listening test?

Hmm just receive my cap from HK... tonight can further upgrade my speaker...

i understand u had sold your proAc 1SC, so what's the speaker u r using now?

WINDWSS,

Don't forget you haven't run in the caps yet. After 200 hours, I think it will be another surprise.

I am always tempted to record down the play back before and after the caps being run in. See if with my recording system, can I reproduce the difference back ... ha.ha.

CAT

Last weekend retest the 1541A dac of my friend which had use 4pcs single OPA and some cap had been chnage to BG. The sound is very diffrent from last time when i heard it....

the bass is much better now....

So no doubt BG is really good cap at signal path for large uf.....

Ha..ha.. I can see them now. It is no fun getting OLD.

lower left

: ) on left corner, the white cable is at the position B  now, previously on position A. A& B is just several cm distance.

u may neey to click the picture, when in larger view u will able to see the word A & B

WINDWSS,

I can't locate your ground cable and the points A, B ..... did I over-look something?

CAT

Cat,

refer my picture, i just shift the white ground cable from position A to B, the hum had reduce >80%....

Finally now can start to enjoy the music....

Dear Cat,

I accidentaly solve reduce a lot my LF hum by just changing the connection point og 1 ground wire.

In case u r using DC filament for the 12AX7 tube. the ground wire should be connected at the negative of the capacitor whuich is closest to the bridge rectifier.

Attached the lates update for u after i make some adjustment last night to get closer B+ Voltage.

Rt - is to cut down the voltage to the plate of 6X4, u don't need that if your transformer is 300V-0-300V and below if use 6X4.

R1--> i use it to reduce surge from the 0.68uf cap (without R1 also ok).  For tube rectifier, 1st cap normally shall not larger than 10uF as the rectifier tube don't like larger uF (the surge may damage the tube)

the other cap & resistor combination is just simple CRC filtering circuit.
R1+R2+R3+R4 will determine the B1+ voltage and will determine the voltage of the cap u want to use.

the value of your R will be determine by how much current use so u need to test out..

I will try to understand that ... It is not easy to see what you have near the transformers .... should be your C-RC circuit?

Now, busy playing with the Pass Labs 1.7

Hi,Cat,

Just finish asemble the Mrz M7 last night, too tire till accidently broke 1 pcs of my 5687 tube..... money gone...

Attach is photo of it, still need fine tuning as got LF hum, should be dur to insufficient capacitance, on the pcb suppose to put 2 pcs of 220uF/450V but i only put 10uF/450V as my 220uf still not arrive.

What the power rating of your power supply? my 1 is 350V-0-350V at secondary, anyway even a 280v-0280 will be sufficient.

For tube power supply, my rectifier tube is 6X4. and i just use normal C-RC filter to obtain the voltage i need.... the value of R is depend on your DC output after rectifier.

current running at 295V & 275 voltge, need to fine tune by changing the R or adding another C-R-C.

Refer my diagram, the 3.3k is to reducue the voltage to tube place as 350V ia a bit high, 6X4 tube's max rating actually ~350-400 dc out.

R1 is to reduce the voltage in my case as i only got 450V cap, so my 295V is in between R3 &R4, and 275 volt is after the R4.  in this case i use 2 pcs of 220k as bleeder resistor. My R4 is ~3.3k which is cause ~20V voltage drop.

In this case if i which to get ~280V & 260V then i just need to increase either R2 or R3 or place 1 more stage of CRC.

for 12ax7 filament i use dc, and connect them using wire from the bottom and the negative just connect using 1 wire to the ground.

Later need to add a metal separator in betweent pwer & signal section...

For B2+, i use 2 pcs wire same length connect to left & right B+ then connect this 2 wire with another wire to the power supply. (i prefer a balance, same distance for both left & right)

Dear WINDWSS,

I need your help on certain issues.

1. When you are done with the Rectifying Section, can you post some photos here? As you said you use Tube rectifying instead of IC, I would like to know how it can be done.

2. Can you draw me your wiring diagram? As I recall I need to add some additional wiring for this board. e.g. I have to connect wires from the first 12AX7 to the other 12AX7 since there are no leads on the board. And, how do you share the the B+ power? You solder a wire from one channel to another? I just wonder how you do this part.

Thanks in advance.

CAT

Good news, finally u find the cause of the hum......

My normal practise is power section will be far away from signal section...

u really fast, my maranzt M7 is not yet completed, recently feel not energy to do soldering work at night..... hopefully by this weekend my preamp will be completed.....

WINDWSS,

I dis-assembled the whole wiring again .... sigh. I finally realised what caused the problem.

I think it should be called "interference" rather than ground problem. It is "ng....ng..." rather than "deeee.... deeee..."

The Toroidal Transformer is placed on top of the Ladder Volume Switch. The volume switch was on the other end of the case in the past. Now I put the selector there and so the volume switch is now on the left, right above the Transformer.

Once I move the transformer away, the M7 becomes quiet as it used to be.

But still, I re-arranged all the wires and it is a mess now inside the case. No time to fix the wires in a "good looking" manner yet.

CAT

Cat,

May be i read wrongly your diagram??

For your RCA out, i saw your ground is connected to the pcb ground near the sgignal out then only to the chasis main---> my suggestion is that this RCA ground shall connect direct to the rca main chasis ground.

When we check or read through the PCB, u will find the ground for PCB (include grn for signal in & out, grn of cathode resistor and so on) all are link together. So i personally feel that it is not so good to mix all ground together.

That's my preference is that RCA grn(in & out) will be sepaate from the grn for chatode bias resistor's grn.

the grn for power supply will go direct to the grn of power cord's grn. The 1st capacitor (the 1 closest to the transformer) will use a separate ground wire direct connected to power cord's grn. Meaning that grn for pwr supply will not connected to the main chasis grn where a lot signal' (small signal)s is there.

Dear Accphoto,

You are right. I think I sort of followed similar arrangement last time. I am not sure whether I got poor memories or what .... I have the feeling that it is much quieter last time.

Anyway, it is always fun to play with this toy. As I have said, if I can afford the time tonight, I will first double check to make sure all the groundings are proper and second, perhaps I try to move the common ground to another point / location and see how it goes.

CAT

Ha Ha, for the point that connect to the Chasis, it is really depends on your luck sometimes. Some one prefer close to the power, some perfer close to the signal. Let see how it goes.

[quote:1c5bccb0e8="ozrayyau"]Thanks All.

So if I like to buy lite DAC with tube, I can pick 60 and 68 only?
AS I know the 68 have a better chips set and balance output, does the 60 is a 24/192 DAC? is it worth to go 68? almost 2k more than the 60 , don't kmow which is a better choice ops:

If Mod 60 VS Mod 68, which one will be the better DAC. of cause both have a same Mod level.

Thanks[/quote]

Do not buy DAC 68. it does not sound great after modification. 68 using AD1853 which is quite different from 1704.

The extra 2K is better used for modification of component for DAC60.

DAC 60 can upstream to 96K, I have not try 192K  and not used whether it can goes as high.

Dear WINDWSS,

I think the diagram didn't show clearly as well... ha..ha..

I DID NOT use the PCB ground point as the common chasis ground. Instead, the point is the HOLE on the PCB to put the screw in to fix the PCB onto the chasis.

But I totally agree with what you said. I think it is better for me to move that point close to the Power Area rather than the Signal Area.

Point 2.

I don't really get your meaning. For RCA IN, there is NO GND going to the selector. For Signal OUT to the RCA, there is NO grounding at the RCA socket.

As the Left and Right Channels are separated on the PCB (2 holes), each Channel has ITS OWN wire leading to the Common Ground; I did not connect Left Gnd to Right Gnd and then to common gnd.

Point 3.

As mentioned above, the Common Gnd actually is NOT the Left Channel Ground. It is the hole for screwing the PCB onto the chasis. Maybe I should take a Macro view so that you can see better ... really sorry for the confusion.

Your advices are really good. I will double check everything and move the common ground point far away from the signal area tonight (if I can afford the time) and see what happens.

As you have said before, it is an interesting game about this grounding issue.

CAT

Hi Cat,

Below are some of my opinion, i migh be wrong:

1) U r using 1 of the grnd point at PCB as your common chasis ground --> i feel that the common chasis ponit is too near to the signal path. For me, i always try to put the common chasis point far away from signal area and close/near to the power cord terminal.

2) 1 set of your RCA ground is connect to another grnd on pcb then only to the common chasis ground --> (become like 2 point ground), i will ground it dirrect to the common chasis ground.

3) since your common chasis ground on the left channel, then just use 1 cable to connect the right channel to the commmon chasis grn. (left & right channel shld only have 1 contact point with 1 cable, if more than 1 point may induce grn loop)


If that's still not reduce your hum then try to replace the 1megaOhm resistor with 470k.

Dear WINDWSS,

Ha...ha.. I think the photos didn't say everything. Let me use the attached the ugly drawing to explain.

There are several points connecting to the common chasis ground.
1. ALL RCA ground are connect using copper wire. Then a wire to the common chasis ground.
2. Power Supply Ground connected to its own chasis.
3. Power Supply Unit has a GND wire connected to the M7 common chasis gnd.
4. There is NO GND from RCA IN to the Selector.
5. There is NO GND from PSB OUT to RCA OUT.

Since I use Coaxial cable, I just ground ONE side, NOT BOTH sides for the Signal IN and OUT.

6. LEFT and RIGHT Channel (PSB) ground goes to common chasis ground (2 wires).
7. First 12AX7 -ve goes to common chasis ground.
8. Volume ground goes to common chasis ground.

I guess that is all. I think the "hum" is still a bit high, can't figure out why. Maybe you and Accphoto can point out some mistakes of mine.

CAT

Thanks All.

So if I like to buy lite DAC with tube, I can pick 60 and 68 only?
AS I know the 68 have a better chips set and balance output, does the 60 is a 24/192 DAC? is it worth to go 68? almost 2k more than the 60 , don't kmow which is a better choice ops:

If Mod 60 VS Mod 68, which one will be the better DAC. of cause both have a same Mod level.

Thanks

Just check that DAC-72 does not have the tube output stage. Better change to DAC-60 in this case.


[quote:e5021faaac="cheapie"]My apologies.  I cannot open the DAC-72 chassis cover to take photos because it is still under warranty.  There is a warranty seal which must be broken to remove the cover.

I guess I'll just have to wait for a few more months, after warranty has expired, before doing anything with / for it.  Or sell it because it seems either it needs the major surgery as accphoto did to his 60 or be abandoned as the present improvement is not that significant with the CD / DVD / SACD players I already have.

:cry:[/quote]

Dear Cat,

After look through the M7 picture u had attached, i have some suggestion which u may test out later to see whether can further reduce your hum...

1) from ur photo it seems your ground from RCA out & in is connected to the pcb ground, then only connect to the centre point(with casing) --> i suggest that the gound will connect dirrect from rac grd to the center point.

If we read through the pcb, the ground on pcb is connected with all signal ground which may cause ground loop.

I also prefer tube stuffs with the same reason, the circuit is more simple and thetube is quite tough, it will not burn/damage easily when wrongly connected, besides, it's size is large so easier for connection , soldering ans it look beautiful when place outside the casing....

Dear WINDWSS,

Don't laugh at me la ... I am just a "technician" or "soldering boy". There are so many things in theory / background that I don't yet understand.

There are so many "good brothers" here around to teach me all these stuffs. They are indeed "Masters" / Shifu .... NOT me.

I am more interested in Tubes stuffs, probably because it is simplier than transistor ones.

It is indeed NOT easy to put things into our mind once we got old. In the morning, we already struggle hard with our daily work. At night, we try to relax and learn something .... ha..ha..

CAT

I just learned that DAC 72 is an IC DAC ... no tubes.

Hi All,

As I know Lite have 3 DAC with Tube, 60, 68 and 72.

If I don't need the Balance output, which is the best DAC? and which is the best if after Mod?

Thank you.

Dear Cheapie,

I recall that posting about the Pre-amp. Just wonder whether I have seen you in any of the Hi Fi Fever Course.

BTW, you are selling your DAC-72. Why?

CAT

Cat, you and Accphoto responded to my call for solutions dealing with hum in a Twins Audio preamp.  So we exchanged messages in the forum.  Can't be sure whether we have met in person unless you also enjoy sailing and running (marathons & trailwalkers).  

Think I am even older.  Whenever I go to a race, people come up to greet me by name but I can't recall their names or where I met them though their faces are familiar.  Ha ha!

Yes, I do look forward to having more time to train for races or pick up sailing dinghies again.  I still have to break the 18-hr OTW (full-team finish) and 3.5 hr full marathon barriers yet.  

:

i believe CAT sir is the fastest learner here, within 1 year already become shifu.... : )

Dear Cheapie,

Oh, let's hope that the business will soon turns good and you will have more projects to work on.

For the time being, yeah, you can spare some time to pick up more from DIY and other interests.

I can't recall whether we met before .... I am getting old ....

CAT

Thanks to members who expressed concern regarding my layoff.  As a senior person, in both age & experience, (project director/architect) of an interior design firm that works mainly for investment banks, I will be the first to go when projects run out.  This has happened to me several times before.  When things pick up I may be recalled.  

The effect isn't that bad.  Now I have time to pursue my other interests.  Ha ha!

:?

Dear WINDWSS,

Not advice ... just sharing. :wink:

I connected the two grounding together in the past and the result is NO GOOD. There are quite some hum and "dee ... dee..." noise.

Accphoto gave me some pieces of advice:

1. For the separated Power Supply, the case is grounded.
2. There is a grounding wire from the Power Supply to the M7 case.
3. RCA ground, Left & Right Channel ground, Volume ground and Tube -ve all are individual wires joining at ONE point grounded with the chasis.

This arrangement seems to be okay so far.

I grounded the -ve wire of the first tube to the Star Ground point mentioned above. I didn't ground each wire.

The rectifier board I am using is a Matisee one. I used the solid state one as it is easy to arrange. If I use Tube Rectifying, I think I need a much larger case. Not much room to house the M7 if I further enlarge it.

I can't exactly recall the values of the caps. I skipped the small value ones, like 0.01uf or so. The rest should follow the value suggested by the board.

Accphoto said this board needs at least 280V to sound good. Mine is set at 280 and it is quite stable.

Cat,

Since we use the same board then better i can get advice from u... : )

Since the board is separate in 2 section, i 'm wondering shall i connect the ground together but worry will create group loop.

Grounding play important role in the noise & hum....so this is something we really need to try and error.

Do u ground the negative pin of filament at each signal tube?
you are using solid state rectifier?? i personally prefer tube rectifier (better imaging, more analog sound)..since u had spend so much on jensen cap, then later just try using rectifier tube lah....
what's the cap value u use? u follow exactly the value given?

Dear Cheapie,

Sorry to hear you are laid off because of the Financial Tsunami

What can I said. you are not a first or last one. some company started on last year.

肥上瘦下

sample AIG獲美政府相救 主管赴海灘奢華度假


http://hk.news.yahoo.com/article/081008/8/8lob.html

Dear Cheapie,

My goodness ... you got laid off because of the Financial Tsunami? What were you working as? You work with the bank or ...?

I am sorry to hear that. I hope that your family won't be greatly affected by this.

CAT