[Pricklely Peete]

Don't forget that to run the 6H30P-i gold pins, DR's or the Sovtek's, the grid resistors (1 for each power tube) have to be changed from 63 ohm to 120 or 121 ohm 1 watt or better rating (I used 121 ohm Kiwame 2 watt).

This isn't an option for the 6H30P-I tubes, it's a requirement.

The stock family of 6N6P and 6N6P-I power tubes are the only types that can be used unless you take apart the MK III and swap out those resistors.

That task is not easy due to the tight confines of the chassis.

The best version of 6N6P-I are those from the Novosibirsk plant made in the early 70's. I believe Yen Audio has matched pairs of this type although I'm not sure what plant his are from. They are NOS tubes no doubt as they went out of production decades ago.

Peete.

 

[esirex]

Quote:

Originally Posted by oofie810 /img/forum/go_quote.gif I actually just missed that by a couple of hours but I see that he's still selling those. I will buy them now. Thanks! BTW, I think I have to start logging out and closing my head-fi windows after I get these. My wallet has taken a fairly good beating for the last 3 weeks.

20 pcs. 6ZH1P / 6Z1P / 6AK5W / 5654 NOS - eBay (item 110296591724 end time Oct-12-08 13:18:01 PDT)

These are voshod tubes but they are unmatch....but i must say they sound much better then the voshod i got from yen audio. And surprisingly it sound better then the tungsol too.

 

[bernado]

Anyone in Europe looking for some good tubes might want to check out this supplier -
MATCHED PAIR-EF92-CV131-6CQ6-TELEFUNKEN-NOS-LITTLE DOT bei eBay.de: Röhren (endet 31.10.08 20:16:58 MEZ)

I bought some matched Telefunken EF92s and power tubes from this guy. Sound better than some previous Mullards I had (although these are supposedly also Mullard made). They sound really good with HD650s and give it some nice bass punch. I had one tube become imballanced which was changed without any fuss.

 

[JimSmiley]

Love the EF92/6CQ6/CV131--my favorite drivers hands down!!

 

[jordanross]

Quote:

Originally Posted by esirex /img/forum/go_quote.gif 20 pcs. 6ZH1P / 6Z1P / 6AK5W / 5654 NOS - eBay (item 110296591724 end time Oct-12-08 13:18:01 PDT) These are voshod tubes but they are unmatch....but i must say they sound much better then the voshod i got from yen audio. And surprisingly it sound better then the tungsol too.

That is ridiculous there must be something wrong with them...

How can he sell 200 tubes for $8. That is a great deal if they actually sound as good as you say.

 

[Pricklely Peete]

Quote:

Originally Posted by jordanross /img/forum/go_quote.gif That is ridiculous there must be something wrong with them... How can he sell 200 tubes for $8. That is a great deal if they actually sound as good as you say.

It's 20 pcs not 200.

Peete.

 

[tonKopf]

My Mk III has just arrived. It only took one week. I am impressed.
It's burning in as I type.
I believe Penchum mentioned earlier somewhere in the thread on how to use it as a pre-amp, but I couldn't find the earlier post again. I've never owned a pre-amp, so I am not sure how to connect it to my Yamaha receiver. What inputs are Ok to use?

Thanks

 

[Penchum]

Quote:

Originally Posted by tonKopf /img/forum/go_quote.gif My Mk III has just arrived. It only took one week. I am impressed. It's burning in as I type. I believe Penchum mentioned earlier somewhere in the thread on how to use it as a pre-amp, but I couldn't find the earlier post again. I've never owned a pre-amp, so I am not sure how to connect it to my Yamaha receiver. What inputs are Ok to use? Thanks

Hey TK,

I talked about it over here: http://www.head-fi.org/forums/f5/rev...1/index57.html in the MKIVse thread.

After reading the two posts about it there, if you have questions, PM me and I'll explain even further. I really is easy.

 

[eboy2003]

Quote:

Originally Posted by eboy2003 /img/forum/go_quote.gif That's one tube gone bad. I had similar issue before, even I didn't try the 6H30Pi-EH before the resistor mod. One tube output volume start dropping and distorting after one minute or so, and I can feel that tube is a lot hotter than the other. I have oscilloscope hooked to the output with 300ohm resistor as load for testing and I can clearly see the output voltage dropping on the bad tube. Luckily I purchased from Yen and he is kind enough to allow me exchange for another set even I just passed the 30-day warranty period. He is my favorite tube source for ever.

Is 6H30Pi-EH very fragile? One of my 6H30Pi died again. The plate turns to dark red and overheats within a minute, then distorting and output voltage drops quickly.

It happens after I switch my Sylvania 6AK5 to Mullard M8161 on MK IV. I did not wait for the tubes to cool down and changed the driver tubes and installed jumpers. Now one 6H30Pi-EH tube is gone bad permanently, I tried it on both LD MK IV and MK III (with resistor mod), the problem persists even without any load.

I can eat the loss and buy another pair from yen, or maybe consider buy a pair of DRs, but I want to know anyone else had similar problems? The original Sovtek 6H30 on MK IV seems more robust. Physically the EH tube looks just fine. How can I further test it to figure out really what goes wrong? I have a B&K 700 tube tester but there is no settings for 6H30, I use 6DJ8 settings to test 6H30 per someone suggest it here, but the tube seems testing fine, and the plate does not turn dark-red after a minute. I suspect it's the heater voltage...

follow up: I add on a 9-pin tube test socket and measured the heater voltage of LD MK 3 and MK 4. The voltage starts at 7.0V AC and then slowly drop to 6.8V AC. A little bit high but seems still within the limit. 6H30 spec says heater voltage 6.3 +/- 0.9V. Still don't know what went wrong for my 6H30Pi-EH.

 

[yamadog1998]

I just received a set of matched nos mullard m8161 today,how ever they will not work in my LD MK 111.What do i have to do to make these work as drivers?I don't know much about tube rolling,Should i have got the m8100?Any and all help is needed,Thank's.

I Should note This Amp works With The tubes it came with.Also The Mullards Light up and can get a faint sound when volume is at full.The settings need to be changed i assume,How do you do that?I Have Tried moving the red switches under the unit,but have no result.

I Just Fixed The Problem With A Set Of Jumper Caps.As far as the Mullards go,All i can say is WOW! The ones i put in were NOS,And i can't believe the improvment.Can't wait to get these baby's burned in.

 

[ScottieB]

Quote:

Originally Posted by yamadog1998 /img/forum/go_quote.gif I just received a set of matched nos mullard m8161 today,how ever they will not work in my LD MK 111.What do i have to do to make these work as drivers?I don't know much about tube rolling,Should i have got the m8100?Any and all help is needed,Thank's. I Should note This Amp works With The tubes it came with.Also The Mullards Light up and can get a faint sound when volume is at full.The settings need to be changed i assume,How do you do that?I Have Tried moving the red switches under the unit,but have no result.

You need to change the jumpers - those are EF92 tubes. Check the manual. If your unit is newer, there will be two switches, also on the bottom, but nearer the middle of the unit. They will be black switches (the red ones are the gain switches, those are set based on the impedance of the headphones you are using). If your unit is an older one, you will have to put jumpers on (like on a hard drive). It is all in the manual.

 

[eboy2003]

Quote:

Originally Posted by eboy2003 /img/forum/go_quote.gif follow up: I add on a 9-pin tube test socket and measured the heater voltage of LD MK 3 and MK 4. The voltage starts at 7.0V AC and then slowly drop to 6.8V AC. A little bit high but seems still within the limit. 6H30 spec says heater voltage 6.3 +/- 0.9V. Still don't know what went wrong for my 6H30Pi-EH.

US 110V version MK III and MK IV users be aware. Please check your local AC voltage with a true RMS multimeter. I have confirmed with Mr. Yang that the US version is designed for 110V AC, given 120V AC (in my case, it's 122V AC) will adds 10% more on heater voltage and reduce the tube life drastically. He suggest put a 1ohm 1w resistor in series for each tube.

 

[sinisterm]

Finally got Mullard EF92 (M8161, large shield). OOB they sound, hmm, harsh, I'll tell my impressions after they get some hours.

Anyone noticed that with EF92 you need to turn volume knob ~5 lines louder to get same sound level as with EF95's? :O

 

[ScottieB]

Quote:

Originally Posted by sinisterm /img/forum/go_quote.gif Finally got Mullard EF92 (M8161, large shield). OOB they sound, hmm, harsh, I'll tell my impressions after they get some hours. Anyone noticed that with EF92 you need to turn volume knob ~5 lines louder to get same sound level as with EF95's? :O

That's not the case with mine (either of the things you mentioned) - you sure the jumpers are set properly?

 

[sinisterm]

Quote:

Originally Posted by ScottieB /img/forum/go_quote.gif That's not the case with mine (either of the things you mentioned) - you sure the jumpers are set properly?

Yeah they are (what a pain in the **** were they to put on, had to use two screwdrivers like chinese eatingsticks

). I didn't mean the harshness as in distortion or anything like that, they just sound harsh, like almost every NOS tube out-of-box I have heard.