[rudra]

Has anyone got around to using a EL3N tube with adapter on the MK VI+. If some one has could you please chime in with your experience. 

 

[kazcou]

  Has anyone got around to using a EL3N tube with adapter on the MK VI+. If some one has could you please chime in with your experience. 

Someone on Feliks Audio Elise thread gave a feedback on this EL3N
12871765
 
 

 

[rudra]

Can someone who has a Bendix or Chantham 6080WA graphite plates let me know what should read in mA. I purchased 4 tubes and I get different readings(one side reads 30 mA and the other side reads 60 mA). Also the protection circuit kicks in. It seem one or more tubes are bad. Trying to figure out how I go about identifying the dodgy ones.

 

[SonicTrance]

Can someone who has a Bendix or Chantham 6080WA graphite plates let me know what should read in mA. I purchased 4 tubes and I get different readings(one side reads 30 mA and the other side reads 60 mA). Also the protection circuit kicks in. It seem one or more tubes are bad. Trying to figure out how I go about identifying the dodgy ones.

The meters should read around 60mA. Try swapping, one tube at a time, from the 30mA channel to the 60mA channel. Then you'll see if you have one or two bad tubes.
You could also measure the voltage drop across the cathode resistors. That will tell you instantly which tube(s) are bad.

If the protection circuit kicks in the meters read 0mA, so I don't understand that. For a tube to trigger the protection circuit it needs to have a near dead short.

 

[eserafinojr]

FWIW my MK6+ reads around 38mA but I got the factory upgraded caps and my power tubes, WE421A/5998s are all matched within 3% Emission and Gm.

Inserting matched quad of TS7236s gives me the same result.

My drivers are Raytheon 5694s, National Union Sound X/tra 6N7Gs or Sylvania Metal Base 6SL7Ws.

I run my MK6 on low gain and it sounds fantastic with tons of power. I also run it with the Little Dot 500 power supply so between that and the factory upgraded caps is probably why my unit runs in the 36-40mA per channel range.

No issues at all and mine doesnt run at the usual 60mA.

 

[SonicTrance]

FWIW my MK6+ reads around 38mA but I got the factory upgraded caps and my power tubes, WE421A/5998s are all matched within 3% Emission and Gm.

Inserting matched quad of TS7236s gives me the same result.

My drivers are Raytheon 5694s, National Union Sound X/tra 6N7Gs or Sylvania Metal Base 6SL7Ws.

I run my MK6 on low gain and it sounds fantastic with tons of power. I also run it with the Little Dot 500 power supply so between that and the factory upgraded caps is probably why my unit runs in the 36-40mA per channel range.

No issues at all and mine doesnt run at the usual 60mA.

If you put some 6AS7/6080's in your amp they will run at 60mA. The cathode resistors sets the current of your output tubes, caps doesn't matter.
You can run your 5998/421A's at 60mA too with much improved SQ. I made a guide in the mod thread.

 

[rudra]

The meters should read around 60mA. Try swapping, one tube at a time, from the 30mA channel to the 60mA channel. Then you'll see if you have one or two bad tubes.
You could also measure the voltage drop across the cathode resistors. That will tell you instantly which tube(s) are bad.

If the protection circuit kicks in the meters read 0mA, so I don't understand that. For a tube to trigger the protection circuit it needs to have a near dead short.

I found the offending tube. The problem is that when I replace the faulty Chatham with the stock tube both the meter read close to 62 mA but I get no sound from either the SE/Balanced output. I bummed as to why the sound is not coming

. If I use the stock Thomson 6080WC or 7236 tubes the audio plays fine. When I use quad 7236 the meter reads 40mA on both sides. The stock tubes read about 62 mA.
 
Left meter reading:

 
Right meter reading:
 

 

[SonicTrance]

@rudra
Those meter readings are good! 
Very strange that you don't get any sound. More tubes must be bad.

 

[eserafinojr]

If you put some 6AS7/6080's in your amp they will run at 60mA. The cathode resistors sets the current of your output tubes, caps doesn't matter.
You can run your 5998/421A's at 60mA too with much improved SQ. I made a guide in the mod thread.

 
Cool. Thanks for pointing that out. But If it requires me opening up my MK6+ and soldering which I'm not very good at, I'll unfortunately have to pass as I don't want to brick this beautiful amp!!
 
Especially since it cost a decent amount more since it's outfitted with high grade caps throughout and dead silent fans from the factory.
 
I had a WA22 previously and the finish of the WA22 is nicer with thicker metal but the MK6 IMHO is a better built and better sounding amplifier. And the analog meters look great as with all Little Dot amps with the MK6's form factor like the X1 and MK8SE.
 

  I found the offending tube. The problem is that when I replace the faulty Chatham with the stock tube both the meter read close to 62 mA but I get no sound from either the SE/Balanced output. I bummed as to why the sound is not coming

. If I use the stock Thomson 6080WC or 7236 tubes the audio plays fine. When I use quad 7236 the meter reads 40mA on both sides. The stock tubes read about 62 mA.
 
Left meter reading:

 
Right meter reading:
 

 
I'm terribly sorry to hear about that. Yes, you likely still have bad tubes.
 
And as ST pointed out to me as well. The 6080 will run at the full 60mA.
 
My Late 50s NOS TS 7236's run at 40 and my Early 50s Pale Grey Plate WE "421A/5998"s run at 38mA.
 
Both sound fantastic with tons of power and no issues with sound. The tubes are likely bad.
 
The 7236 has great dynamics and sounds a little more dry and "tighter" where as the 421A/5998s have more top and bottom extension but are slightly looser sounding.
 
Overall my favorites are the Western Electrics.
 
I have a large stash of 7236s, I would be happy to loan/sell somebody a matched quad. Amplitrex Tested.
 
BTW has anybody modded their MK6 to handle the extra current draw of the TS/Cetron or Raytheon 6336, 6336A, CK6336 or the 6528 power tubes?
 
They have the same pinout of the 6AS7/6080, run at 6.3Vs but draw much more current so I doubt the MK6 could handle them without frying it or shorting something!!

 

[rudra]

@SonicTrance and @eserafinojr thanks for your advice. In the end it turned out that 2 out of the 4 tubes were dud. Disappointed(the shipping cost of the duds back to the USA from Oz is a real kicker) but the seller has agreed to replace.

 

[eserafinojr]

  @SonicTrance and @eserafinojr thanks for your advice. In the end it turned out that 2 out of the 4 tubes were dud. Disappointed(the shipping cost of the duds back to the USA from Oz is a real kicker) but the seller has agreed to replace.

 
Of course and I'm happy to hear it worked out with the seller.
 
Good luck. Hopefully you'll get them soon!
 
I think you'll really enjoy the 7236s..
 
They have this very tight, dry and extremely dynamic solid state-esque sound signature.

 

[SonicTrance]

BTW has anybody modded their MK6 to handle the extra current draw of the TS/Cetron or Raytheon 6336, 6336A, CK6336 or the 6528 power tubes?
They have the same pinout of the 6AS7/6080, run at 6.3Vs but draw much more current so I doubt the MK6 could handle them without frying it or shorting something!! 

Correct. You need external heater psu for those tubes. The MK6 is only good for 2.5A/output tube socket.
 

The 6.8V 5A winding is for one channel power tubes.

 

[ViperGeek]

I have a question about "mostly" matching left and right channel power tubes.
 
As I've shared a couple times, I have a laundry list of favorite tubes to try.  Right now, my favorites (I can afford) are: 
 
* Shuguang Treasure CV181-Z black bottle driver tubes
* RCA 6AS7G vintage NOS matched power tubes
 
Recently, at least one of my 6AS7Gs lost its mind, so I'm back to the stock RCA 6080's that came with the Mk VI+.
 
My current laundry list of haves and must haves are:
 
Tung-Sol CTL 6SN7GT Black Glass Oval Round Plate (Driver Tubes) | eBay
RCA 6SN7GT / GTB Black Plate (Driver Tubes) | TubeDepot.com
RCA 6SN7GTB (Driver Tubes) - TC Tubes
6SL7GT RCA (Driver Tubes) | TubeDepot.com
Tung Sol USA 6SL7GT Black Round Plates (Driver Tubes)
* Tung Sol 6SL7GT Cryo Treated (Driver Tubes)
* CV181-Z Select (equivalent to 6SN7) (Driver Tubes) | Psvane & Shuguang Treasure Audio Tubes
CV181-TII aka 6SN7 (Driver Tubes) | Psvane & Shuguang Treasure Audio Tubes
Sophia Electric™ Premium 6SN7 (Driver Tubes)
Bendix 6080WB Graphite Plate (Power Tubes)
* RCA 6AS7G (Power Tubes) Matched Pair
Tung Sol 5998 (Power Tubes) | Tubes Unlimited
Winged "C" 6H13C / 6AS7G (Power Tubes)
Vintage Svetlana "Winged C" 6AS7G / 6H13C (Power Tubes)
 
For a while, I've been pining after the Bendix 6080WB Graphite Plate power tubes, but can only find two.  Recently, I also found a pair of Tung Sol 6080WBs:

www.etsy.com/listing/216545733/pair-tung-sol-6080wb-vacuum-tubes
 
My question (finally) is, would the Little Dot Mk VI+ appreciate having a pair of Bendix 6080WB's in the left channel and Tung Sol 6080WB's in the right channel?  My contact states that the difference in gain between all 8 plates in both sets of tubes is around 5-6%.  Would that throw off the audio balance, or would the Mk VI+ automatically adjust for this gain difference?
 
Thanks!
 
- Dave

 

[Maxx134]

they are both 6080wb , so they have same specs, so i dont see a problem.
 
Also, I have experimented in past a mix which can be done , only when using same spec tubes:
 
what  I would suggest, is to place one of each brand on same side(!)
the left (positive) socket of each side will provide the dominant characteristic of the pair.
This insight is from my testing.
Also suggest all to at least read the "supermod" thread just to at least gain insights on your amp inner workings...

 

[ViperGeek]

  they are both 6080wb , so they have same specs, so i dont see a problem.
 
Also, I have experimented in past a mix which can be done , only when using same spec tubes:
 
what  I would suggest, is to place one of each brand on same side(!)
the left (positive) socket of each side will provide the dominant characteristic of the pair.
This insight is from my testing.
Also suggest all to at least read the "supermod" thread just to at least gain insights on your amp inner workings...

 
Thanks Maxx.  I thought about perhaps mixing them L+/R+ and L-/R- as described by you and (I believe) @coinmaster in the past.  I just wasn't sure if the comment from the seller about the 5-6% gain difference would be a problem.  Would having more gain on the + side than the - side cause a "lopsided" signal?
 
I'll thumb through the Super Mods thread again, although I have to admit: much of it is beyond my ability or modding needs. Still an informative read, though.
 
- Dave