[baronbeehive]

Here you go, found it, near the beginning luckily:

"Hi Guys I've just found this thread so I've copied my post which I put on the mk vi thread which has now ceased.

I thought I would throw in my tuppenny worth because there seems to be so little information on the mkvi and would like to contribute something to the discussion on this fantastic amp having been helped by forum members previously. My set up is: PC>FOOBAR>USB to TOSLINK>CHANNEL ISLANDS AUDIO BALANCED DAC>ALO AUDIO SILVER COATED COPPER RCA'S>LD MKVI+>AUDIO TECHNICA ATH AD2000'S and SENNHEISER HD600's. I'm going to go ahead and assume this is the correct thread so here goes!

Previous to the mkvi I owned a mkiv se and always loved it with the standard power tubes and Tung Sol 6ak5w driver tubes which gave a much clearer warmer and less overpoweringly tubey sound than with the original m8100 driver tubes. The only upgrade I could think of from there was to go balanced to get the next step in up in SQ therefore I went for the mk vi a year ago. So far I've only used it single ended due to financial constraints! Since owning it I wanted to get the mkiv sound back which I loved and came close to it with raytheon vt231 6sn7 tubes. However I liked the slightly more tubey sound that the 6sn7 driver tubes gave me over the mkiv sound whilst still retaining the detail, it is a tube amp after all! This is why I like the amp so much, but if any one wants to know how it sounds then refer to the mkiii or mkivse review for close approximation as the sound signature is similar according to others, with the mkiii slightly warm and the mkiv slightly clearer but taking the sound up a notch again.

TUBE ROLLING. What follows are my observations from memory on the other tubes I've tried, and how they affect the sound of the amp. There is a good choice with the 6sn7 tube family which are suited to this amp and are all great tubes. The rca 6sn7 gtb are beautifully rich, detailed and balanced, whereas the vt123 grey glass tubes are musical, very balanced and exceptionally smooth and easy to listen to. The sylvania 6sn7 gtb are warm, detailed, balanced, crisp and slightly solid state sounding. The tung
sol 6sn7 gtb sound clear, detailed and analytical. Brimar cv1988 tubes are very dynamic, punchy, tubey and fantastic for mid range vocals, especially female. Finally the tung sol oval plate tubes are about the best I've tried with a beautiful balance, detailed base and magical silky treble and 3d soundstage. If anyone wants any further elaboration please let me know as I have had to find most of this out for myself with a little help and I would be pleased to respond with my own observations. I've also tried some tung sol 7236 power tubes which are very clear, detailed and analytical sounding. The only tubes I would like to try now are the sylvania 6as7g power tubes which are supposed to be warm, detailed with a good soundstage and I would like to contrast these with the rca 6as7g power tubes that I've been using up to now. I've tried examples from the main tube families so I would think that within these families the tubes all have a similar sound signature eg sylvanias are all warm and crisp sounding whereas rca's are smooth and rich sounding etc. I've also tried all the main construction types eg flat plate, round plate, t plate etc so have got a rough idea of these sound signatures. Anyone can get an overall picture from various tube sites.

I hope this gives and indication of characteristics of the mkvi. I love it and for the value and also the customer experience I am really impressed. I can't see me ever changing the set up - possibly! In the future I do want to go balanced however with some HiFiMan HE500's which can be easily recabled unlike my Audio Technicas. It they are as good as the reviews say then I will have the perfect set up - great sounding amp with no faults that I can detect, and one of the best sets of headphones around!!!

Finally regarding the hum, I did think that it had been sorted with the later mkvi's. Mine is a mkvi+ and I don't get this humming noise, all I get is the quiet whirring of the fans which is not a problem. Just occasionally I do get a slight hum on one or other channel which I put down to interference of some sort, either my own system or from other networks possibly, or the tubes. I'm not an expert on this but this noise never lasts and is never intrusive.

Great to come across this thread at last, carry on the good work!"

Edit: so if you like smooth, live type sound you could try Raytheons, refined, balanced sound -RCA's, light, crisp type sound - Sylvanias, Silky, liquid sound -Tungsols, finally dynamic, euphonic sound try the Brimars.
I think I updated this post later but this should give you some idea.
Oh and Bendix 6080WB's are one of he best power tubes, open, detailed, smooth, dynamic sounding.

 

[SonicTrance]

The only tubes I would like to try now are the sylvania 6as7g power tubes...

So, did you ever find those? Most Sylvania 6AS7's I've seen are RCA rebrands.

 

[baronbeehive]

So, did you ever find those? Most Sylvania 6AS7's I've seen are RCA rebrands.

No, I gave up looking, from what I heard about them from other members they were not all that detailed anyway so I forgot about them!

Edit:

I have just one other tube I'm going to try, the 12SL7 GE, and this came about because I have it on the APPJ and found it to be very transparent sounding but a bit thin and slightly harsh on that amp. It made me think though that because the modded LD is very rich sounding it might work well on that so as I already have one I decided to order another at the princely sum of $5, very cheap so I think I can get away with it.

The thing about the GE6S7's is that none of them seem to have very good reviews so I overlooked these at the time but the 12SL7's are different construction with rounded centre flat silver plates which made them slightly different from standard.

Anyway I will report back when I've tried them.

 

[Maxx134]

Yeah Jupiter are definitely great Speaker caps, for headphone amps and for my tastes, i just find them bit too flat

Just to be clear which version of Jupiter where you using?
the bees wax,
or the copper foil?

I found the beeswax to be a bit thick and not as good as any others mentioned here.

 

[bloodhawk]

Just to be clear which version of Jupiter where you using?
the bees wax,
or the copper foil?

I found the beeswax to be a bit thick and not as good as any others mentioned here.

Copper Foil.

 

[bloodhawk]

ooooh boy, TS5998+6H13C+TS5998+6H13C with the Sylvania VT-231's makes the amps soooo much better. And this is without the mods. Cant wait to try out the CV181-TII's once they get here next week.

 

[MrCurwen]

Just as a sidenote;

In cyrillic script H is N (en) and C is S (es), so 6H13C is 6N13S using latin letters.

How's your soldering skills, bloodhawk?

 

[bloodhawk]

Just as a sidenote;

In cyrillic script H is N (en) and C is S (es), so 6H13C is 6N13S using latin letters.

How's your soldering skills, bloodhawk?

Pretty awesome

I have done a lot of SMD soldering, modding GPU's for LN2 / Power mods etc. The BH Crack was pretty much a piece of cake.

Caps should be here Monday.

Some observations regarding the Tung Sol 7236 tubes ( I grabbed 4 of these NOS)

- 3 are dual round getters (Horse shoe?)

- 1 of these is a dual rectangular getter.

- All 4 are grey plates.

Observations -

- Out of the 3 round getter tubes, 2 have orange text printing. One is the standard Black text. Here is the interesting part, the orange text tubes, sound way more dynamic than the black text ones. They even Bias higher.
Black Text tubes Bias @ about 50-52 ish. Orange tubes are Biasing around 55-58ish.

- The Orange tubes actually sound better to me than the standard 5998 (NOS) that i have been using.

- The mids are definitely a tiny bit more forward, but there is more texture to the low end, and there is bit of more added mid/sub bass. This is without sacrificing the treble clarity / texture or the openness.


Also the order the tubes are placed in matter way more with the 7236's. Im guessing because of the
lower trans-conductance vs the 5998's.
With the 5998's i couldn't tell any difference. (2 x 5998's + 2 x 6H13C)
But with the 7236's, the 6H13C's need to be first in order - 6H13C + 7236 + 6H13C + 7236

 

[baronbeehive]

Pretty awesome

I have done a lot of SMD soldering, modding GPU's for LN2 / Power mods etc. The BH Crack was pretty much a piece of cake.

You should be good for the mods then. I see you've done the Speedball mod to your Crack, we're doing a similar mod to the LD atm!

Re: your tube choice, I get the feeling you like the really in your face detail type tubes, in which case you will love the Winged "C", and the Psvanes. The RCA's are not liked by everyone, I associated their sound with the first time I got the LD and was blown away by it. You might be interested in the GE's when I eventually get the last one, they have a really clean sound and extended treble. I will post on them. I much prefer them to the Sylvanias which I don't like, the sound of the GE's is much purer for me.

 

[bloodhawk]

You should be good for the mods then. I see you've done the Speedball mod to your Crack, we're doing a similar mod to the LD atm!

Re: your tube choice, I get the feeling you like the really in your face detail type tubes, in which case you will love the Winged "C", and the Psvanes. The RCA's are not liked by everyone, I associated their sound with the first time I got the LD and was blown away by it. You might be interested in the GE's when I eventually get the last one, they have a really clean sound and extended treble. I will post on them. I much prefer them to the Sylvanias which I don't like, the sound of the GE's is much purer for me.

NICE! Really interested in seeing how those mods turn out and a worklog if possible.

Umm kinda. But i do love a spacious soundstage as well. Im right there with you about the RCA's they were highly disappointing for me tbh. Specially when compared to my Crack running a 5998+E80CC or 5998 + Mullard / Telefunken 12AU7.

Do you mean the GEC 6080 / 6AS7 ? I have been looking for both and its been really hard find a pair for a reasonable price, let alone matched. The normal GE's sounded very plain to me, definitely a step over the RCA's and very balanced when compared to the bass monster 6H13C's. but way down the chain vs the 7236 / 5998.

Cant wait to try out the Psvanes on Monday.

 

[baronbeehive]

Do you mean the GEC 6080 / 6AS7 ? I have been looking for both and its been really hard find a pair for a reasonable price, let alone matched. The normal GE's sounded very plain to me, definitely a step over the RCA's and very balanced when compared to the bass monster 6H13C's. but way down the chain vs the 7236 / 5998.

Cant wait to try out the Psvanes on Monday.

No the GEC's are an entirely different kettle of fish and are very good I believe, SonicTrance has them. I was talking about the 12SL7 GE's which I had on my APPJ, I agree that GE's are not particularly exceptional in general but I have a feeling that the transparency of the 12SL7's would be good in the LD post mods. BTW I hope your wallet recovers quickly from the Psvane purchase....

I kept a work log of my mods for anyone trying them here:

SMLD MODS: (continued)

Driver Bias Mod - The idea is to optimize bias on driver stage. The total resistance at the anodes was changed to 33k ohms, the total resistance at the cathodes was changed to 390 ohms, as suggested by SonicTrance for the MKVi+, to change the operating point to a more linear part of the driver tube load line.

Like Maxx134, I decided to add resistors to existing. The alternative is to remove existing resistors and solder in new ones.

New resistors soldered in parallel to existing anodes:



New resistor soldered in parallel to existing cathodes:


You can follow my mods pages: 50, 53, 55, 57, 62, 65, 66, 68, 69, 70, 71, 72, 147, 179 which include pics. Also Mogos mods are here; 33-38, and SonicTrance here: 23, 43, including some great pics.

 

[baronbeehive]

Do I need to change any other resistors next time I get the back off?

I've changed the 8x330ohm power resistors, the 4x220kohm anode resistors, and the 2x1.5kohm cathode resistors as part of the mods. As for the resistors near the PSU, I changed the 2x8k2ohm resistors but one resistor near these is going burnt and looks like it needs changing, not sure which one this is, possibly the 2x5k1ohm resistors. I can't check it until I next get the back off to do the CCS mod, but last time I checked it was still reading fine.

 

[baronbeehive]

This one here:

On some boards this one is paralleled.

 

[bloodhawk]

No the GEC's are an entirely different kettle of fish and are very good I believe, SonicTrance has them. I was talking about the 12SL7 GE's which I had on my APPJ, I agree that GE's are not particularly exceptional in general but I have a feeling that the transparency of the 12SL7's would be good in the LD post mods. BTW I hope your wallet recovers quickly from the Psvane purchase....

Ahhh i totally got them confused for the Power Tubes, i haven't tried the 12SL7's yet though.

The wallet should recover once i finish the porting over my Crack into a new 10"x10" chassis and sell it I have a feeling with all my mods and the convenient driver tube bias switches, it should fetch a decent amount.

Hoooly Shiitt... PSVane CV181-TII's.

I dont even know how much more better things can get...

 

[baronbeehive]

Hoooly Shiitt... PSVane CV181-TII's.

I dont even know how much more things can get...

Ha, ha, I've heard about them!!