[SonicTrance]

  Ok this is pretty CRAZY!!!
 
I changed the tube settings:  socket 1 Thomson, socket 2 RCA, socket 3 Thomson, socket 4 RCA.  It seems like socket 2 and socket 4 are  dominant or something.
 
Now I have this crazy awesome bass, very full sound, with creamy liquid mids and highs.   I might have just discovered a hidden secret of LDMKVI+.   I didn't know my HD650 can sound this good!!!

  My HD650 shouldn't sound this crazy good.  Something is definitely not normal here.  I can't explain what is happening but this is some crazy good schiit!!  You guys have to try this!!! (at your own risk)

 I wish there's some kind of Headphone Meet near where I live so I can bring my LDMKVI+ and let others listen to it hear them say "WOWWWWWW!!!" 

 
Poladise, you have to try this.  Don't even bother getting RCA 6AS7G.  Just get two cheap RCA6080 because you already have Thomson 6080WA.
I was always trying to get matched quad power tubes because I just thought that's how it must be done.  I didn't use my RCA6080 or Thomson 6080WA by themselves because they just don't sound good.  I might have just unlocked the secret power of LDMKVI+ of it's versatility of letting users mix power tubes.
 
I have been using this for more than 10 hours and nothing happened.  Temperature seems just a tiny bit warmer but nothing else seems to be wrong.

This is very interesting. I'll try this out when mine arrives for sure! =)  

 

[Poladise]

  Don't even bother getting RCA 6AS7G.  Just get two cheap RCA6080 because you already have Thomson 6080WA.

 
I couldnt find a 6AS7G set anyway. I ordered a Violectric V200, so I have a reference for the kind of full bodied vivid sound I've been wanting to achieve with a tube amp. I might end up keeping just the V200, but I havent given up on the VI+ yet: I just ordered some RCA 6080s. Got 4 just in case I prefer them on their own instead of mixed. Interesting find Soundengineer.

 

[Maxx134]

Thanks for confirming that these are the best resistors that I could use for LDMKVI.  I was thinking about taking these out and going with metal foil resistors but I couldn't find any that were 330ohm 5W.  I guess I will leave them in.

What resistor value do I need for all the resistors you circled that are in the signal path?  Even tho I am more than satisfied with my sound right now I want to experiment with some high end name brand resistors to see if I can make even more improvement.  But I have no idea how to calculate or find resistor values.  Please let me know if you know the values.  Thanks

Correct metal foil is best and can be only used in input stage as none are made high watts..


I cannot recommend you my resistor values in preamp tube stage because I have different driver tubes(12at7),
so you can check the board under the resistor may have it written,
OR last resort take out and measure but that would mean no working amp till U get replacement parts ,
which on ebay you can get a good deal buying the caddock foils:

that an example of the four I need and another two more of another lesser value..

I was going for these but at last minute turned raving mad...


I bought the Vishay metal foils...


Look!

The way I see it, is if U going to go thru all the trouble to open up and work on it,
replace with most noticable potential for improvement,
or you may not notice enough for the effort involved...
Especially when the amp is already at a level where almost everything is at 1% tolerance or better...

 

[Redge78]

Maxx,
 
You surely realised that you will have to put those "my precious" tall resistors just below your huge Mundorf caps ... didn't you ...
 
Good luck with that ! 

 
 
 
And you chose the "naked" version, on top of that ... that would have been too easy otherwise ! 

 

[Maxx134]

Noooowwahhhh!
Y didn' I see this. .
I couldn't resist it being naked...

Lol I don't care I'll make it fit!

 

[john57]

That is interesting flat resistors, not the most common I have seen. 

 

[G600]

I'm worried to see the thread going in a dangerous direction.
 
While being top notch resistor, those naked Zfoil are fragile and are not rated for a tube amp, hardly for the input stage.
 
And mixing power tubes, that's borderline crazy. You must ask Sword Yang at LittleDot about this.
Somebody earlier said that with the servo, nothing bad can happen with DC.
Never forget those opamps have a range, if anything goes beyond, it's going to hurt badly.
 
Just imagine frying your amp, your cans, and why not your ears !
I see some members that a month ago were afraid to unscrew the bottom plate, and now don't hesitate to rebuild the amp.
Guys, keep low profile and think twice before regretting what you did.
 
Anyway, those amps are wonderful.

 

[Maxx134]

Hmm.. U R absolutely correct. .
I have to agree,


this is a not a modding thread,
and so it's very dangerous road for the untrained,
not only because of what was stated,
but Because it's tubes.

Need to know what Ur doin a bit to not get killed with high voltages from caps.

For those that pass the issues stated,
need to PM & or start a mod thread..
I won't volunteer because I don't want to be blamed (!) Lol

Personally, I am convinced LD has the potential to be crush the majority of competition out there Just with the cap mod.

 

[SoundEngineer]

  I'm worried to see the thread going in a dangerous direction.
 
While being top notch resistor, those naked Zfoil are fragile and are not rated for a tube amp, hardly for the input stage.
 
And mixing power tubes, that's borderline crazy. You must ask Sword Yang at LittleDot about this.
Somebody earlier said that with the servo, nothing bad can happen with DC.
Never forget those opamps have a range, if anything goes beyond, it's going to hurt badly.
 
Just imagine frying your amp, your cans, and why not your ears !
I see some members that a month ago were afraid to unscrew the bottom plate, and now don't hesitate to rebuild the amp.
Guys, keep low profile and think twice before regretting what you did.
 
Anyway, those amps are wonderful.

I agree with G600 and I fully understand his concern.  Thank you for sharing your concerns.
I agree with G600 and I would not recommend others of doing this unless someone can verify with Sword Yang that this is ok to do.  
 
IMHO, I don't see that this LDMKVI/VIII owners thread is any different from LDMKIVSE owners thread which had impressions about improved SQ from modding and trying different tubes that were not even designed for it.  In result, lots of LDMKIVSE owners got to enjoy SQ that can't be produced by stock LDMKIVSE.  
IMHO, we have mix of LDMKVI/VIII owners who are DYI people who want to push their amp to it's max capability and there are people who just like to enjoy the sound it was originally intended by the designer...and some in between.  I would not recommend others to try what I did unless they can verify with Sword Yang or some qualified professional who knows about LDMKVI/VIII.
 
 
Here is my update:
I left my mixed power tube amp on for about 8 hours straight last night with my fan on at the lowest speed setting with random music playing.  It was turned off for about 3 hours this morning and I left it on again for another 8 hours with random music playing with my HD650 connected to the balanced output.  There is no change in SQ (still crazy good) or temperature change of the case.
 
The warmer temperature was not from mixing the tubes...it was actually from 6080 tube design.  They have wide metal base that is closer to the decoration ring that transfers more heat to the case.  This is why it was warmer than using my 6AS7Gs not that my amp was working harder or something was overheating.
 
I have been using it with mixed power tube for about 26+ hours.  I opened up the case and everything seems to be in normal condition.  I will be using this mixed power tube setting for awhile because I haven't found any matched quad 6AS7G or matched quad 6080 tubes that can beat this Musical (it's much proper to say Magical) SQ.
 
All I want to do is share what I have found so far for those who are interested.
 
Please do not try this unless you can verify with Sword Yang or someone who is a qualified professional.  I do not recommend anyone to do this.  I do not want anyone to fry their amp, cans, or ears.

 

 

[Maxx134]

...
While being top notch resistor, those naked Zfoil are fragile and are not rated for a tube amp, hardly for the input stage.

I just want to point out that from my observations,
my first concern and issue was about power handling and if you look at existing resistors they look at best like a 1/4watt(.25),
Actually smaller:

The 2*3 resistors in the signal path are DALE RN55C (Metal Film Resistors) 0.1% Tolerance
- Very low noise (- 40 dB)
- Very low voltage coefficient (5 ppm/V)
- Controlled temperature coefficient
- Flame retardant epoxy coating 
..

So the z-foil is .4watt which is around double the power rating,
and so my only remaining concern is that she is naked..

 

[Maxx134]

I clearly stated q while ago that the resistor upgrade over those blue piece of sh... is as big as the cap upgrade.
I don't know if there is any metal into those metal films, but them being in the signal path is naughty.

This leads me to believe that they are ..
Edit:
I have come to the belief that they are just metal films that are not of a quality capable of the heat & wattage.
extra thick means nothing as it is whats inside that matters.

Also although they feeding the tube's, they are not actually in signal path as the power tube is getting signAL from the capacitor.

You know mundorf makes resistors too right? :wink_face: . Also wirewound resistors are inferior to metal film resistors so there could be room for even more improvement.

while this is true I have realized that the resistor type plays important role and for the role the big resistors is used for power not signal quality, so in that sense we need power handling and low noise under high heat.

The designer originally chose the dale wirewound, and so I am not second guessing with these larger metal film replacements that are not realy meant for what they are in now...
Metal oxide is a better choice for that high wattage but my guess is deaigner did not want to conpromise on the better tolerance that the metal films give.

In fact my unit being just made a few weeks ago has more metal films in compromised areas like power supply, compared to older board pics.

It was a move away from older stock dale resistors to newer unknown make metal films,
that can be from any asian manufacturer,
and in itself is nothing wrong, just not optimal for higher wattages.

Again Must note that the ONLY concern I found was the higher wattage resistors (2w on board).
Not many metal films go that high to begin with,
So its understandable there would be wear.

Here is a pic examlple of what is being passed of as the new dale resistors look like:

But in my search dale still not make their resistors blue..

So these are very much like any stock metal film of asian manufacturers that make & sell their parts to companies who rebrand them to their names.
LD may be getting them from the source.

The critical parts still look excellent and caps too .
I will be going over the tiny stuff with a critical eye..

Again, so far the weak parts I am only talking about the power resistors throughout board in power supply area and the 8 mention earlier for power tubes...

 

[Maxx134]

After comparing more I see on my MK8 board:

all the larger black capacitors in power supply area have been upgraded to larger cpacitance or voltage.

For instance large caps are now 1200uf instead of 1000uf,

and the 330uf is now 250v instead of 200v.

And the red wima caps thruout board are now wider voltage spec MKP10 instead of older mks4.

And The signal coupling caps of preTube stage have also been upgraded to .33uf from .22uf

I was also notified of resistor value change for more stability of the MK8



So in my view key upgrades to performance have been improved upon,
regardless of the new blue resistors mentioned.

 

[SonicTrance]

  MisterX,
 
Are you using C3G or C3Gs for your MKIVSE driver tube and 6AS7G for power tube?  If you are...I am very very interested on your impression when you get your MKVI+.  I want to know how they compare to each other.  I was going to get MKIVSE and do the mod like you did but I had an opportunity to buy a 2nd hand MKVI+ for $100 more than MKIVSE so I skipped to MKVI+.
 
Please let me know after you listen to MKVI+

I now got my mkvi+ up and running! I'd like to give you my first impressions.
 
First a few negatives:
I get noise from the SE output (like almost everyone else it seems)
The stock fans was VERY loud, replaced them asap with some Noctuas, dead quiet now.
 
Other than that it's an amazing upgrade from the mkivse (I'm keeping that too though). I re-terminated my W1000X today and OMG what a difference it made. They sound amazing balanced! I'm using the LD Dac_1 as source btw. Soundstage is much bigger and separation much clearer. I thought these cans sounded good before, but now I'm blown away!
I'm currently running 6H5C's as powers and Psvane uk-6SN7 as drivers. Got some Mullard 6080's and Psvane Treasures on the way though.
 
Running the mkvi+ in SE mode and try to ignore the noise, it's on par with my modded mkivse in sound quality. I'm never using that SE output again though

 

[baronbeehive]

I loved my MKIVSE too, and the person I sold it to was blown away as well. That was when I had my ATH-AD2000's which I believe the W1000X is a great upgrade for! I'll be interested to know what you think of the Mullards.

 

[SoundEngineer]

  I now got my mkvi+ up and running! I'd like to give you my first impressions.
 
First a few negatives:
I get noise from the SE output (like almost everyone else it seems)
The stock fans was VERY loud, replaced them asap with some Noctuas, dead quiet now.
 
Other than that it's an amazing upgrade from the mkivse (I'm keeping that too though). I re-terminated my W1000X today and OMG what a difference it made. They sound amazing balanced! I'm using the LD Dac_1 as source btw. Soundstage is much bigger and separation much clearer. I thought these cans sounded good before, but now I'm blown away!
I'm currently running 6H5C's as powers and Psvane uk-6SN7 as drivers. Got some Mullard 6080's and Psvane Treasures on the way though.
 
Running the mkvi+ in SE mode and try to ignore the noise, it's on par with my modded mkivse in sound quality. I'm never using that SE output again though

Congratulations!!! That's awesome that you are blown away.

 
Those Psvane UK-6SN7 are truly a bargain for the SQ that you are getting.
 
I am also eagerly waiting for your impression on Mullard 6080.