[SemiAudiophile]

Quote:

Originally Posted by Penchum /img/forum/go_quote.gif Well, before I did the resistor change for 6H30 family tubes, I was running my MKIII for 8 hours, then a cool down to room temps, then more 8 hour sessions and so on. I did this for at least 1000 hours total. When I took her apart for the mod, I had no signs of heat related problems. I think what we see in the above pics, is all related to running two sets of 6H30's (until dead) without doing the resistor mod. If anyone running the stock power tubes (6H6N family) is worried about heat problems, it is easy to unscrew the back two screws and look at the resistors with a flashlight. The best advice still stands as stated way earlier in this thread; "If you want to move to 6H30 family of power tubes, you MUST do the resistor mod first!" I've been running my "resistor modded" MKIII, using 6H30PI-EH power tubes for at least 750 hours total so far. I have not had any heat related issues so far. The same goes for my MKII modded as well.

i want to run the 6H30 family of power tubes. what kind of resistors do i need? and where to get them? HELP pleeasssee.

 

[eboy2003]

Quote:

Originally Posted by SemiAudiophile /img/forum/go_quote.gif i want to run the 6H30 family of power tubes. what kind of resistors do i need? and where to get them? HELP pleeasssee.

You can use my MK III board picture as reference, the 120ohm resistor is the one near the green ERO 0.22uf capacitor, one for each channel. The original value was 68ohm, change that to 120-150ohm/2w resistor.

 

[SemiAudiophile]

are u referring to the two resistors circled here?

 

[eboy2003]

Yes.

 

[SemiAudiophile]

sweet! now i just need to know where to find the 120-150ohm/2w resistors and learn how to solder.

 

[odymmij]

I'm getting my amp soon and am excited to roll some tubes!

So...which tubes would sound better, 6J1P-EV or M8100?

 

[SemiAudiophile]

just an update on the M8161 small shields. after burning them in 8hrs/day this past week i find these tubes are pretty awesome especially for its price. i would definitely not pass on these especially for starter tubes since they are pretty cheap and make significant improvements to the mkIII. i think i got them for about $24 shipped on ebay. although, i am quite curious to hear what difference the large shields have to offer hehe (i'll just have to wait on that).

another suprising thing is that i realized how well-rounded this amp really is. i already knew that the mkIII matched well with my grados and meh with the k701s. but, after tube rolling the mkIII and grados sounded even better, k701 with mkIII= now a good match (quite breathtaking actually), and also after changing my gain->10 mkIII and hd650 also a good match. i was scratching my head earlier wondering why my hd650 still sounded a bit veiled, "airtight" feeling even after tube rolling because i always kept my gain setting at 5 (it didnt make much difference with stock tubes).

if i were to describe this amp with the new tubes in a sentence it would be "liquid smooth, yet elegant".

now just waiting for the 6H30PI-EH's so i can start modding muhaha. i was able to find some resistors from a local electronics shop.

 

[Anavel0]

@ eboy2003

Did you do any other mods to your MK III? Because it definetly doesn't look like mine. Specifically the absense of the 3 Rubycon caps, I also noticed some others do not look the same either. Or maybe it was just an older revision? I know Little Dot did make a couple of changes to the MK III.

 

[SemiAudiophile]

hmm...i'm having a bit of a weird problem. received the amperex 5654 PQ's today, but when i popped them in i'm get this weird feedback. i can hear some static coming from mainly the left channel but sometimes the right too. i play some music through them and it sounds amazing however the feedback is kind of annoying. another thing is when i first turn the amp on, i notice that the left tube glows extremely bright for about a second and then dims back to normal. at first i thought it was the amp, and unscrewed the back and checked inside. but couldn't find or smell anything. then i switched the stock tubes back in and everything was fine. so could it be the tubes that are bad or what??

also just curious, how do you slide out the circuit board? i was trying to figure it out when i took apart the back panel and the top transformer.

 

[karthur]

Thanks to this great forum and the detailed reviews I am now broke, but also now the proud owner of a Little Dot MK III and a whole lot a tubes/valves...

Preliminary review, this is based on the tubes being burned-in for no more than a few hours.

Headphones: Grado Sr225s.
Source: Auzentech X-Meridian with TI Excalibur TLE2072IP Opamp (I'm waiting for my OPA627s to arrive)

Russian EF95 6Zh1P-EV Voshod 1974-1978 - I have seen some good reports about these but I don't find them to suit my tastes at all. They give a real vinyl quality to the music (the sound of a cheap record player). The bass is ok not great, but the highs seem harsh and a little tinny.

Mullard M8083/CV4014/EF91 small logo - Sound seems quite accurate although with a slight "tubeyness". Good bass, fluid mids, accurate highs, not harsh or smoothed-over.

Mullard EF91 M8083/CV4014 large logo - pretty close the small logo ones, can't really tell much of a difference. No distortion problems.

Mullard EF92 CV4015 M8161 9D6 KQDDK small logo - Very similar to the EF91s - sound seems quite accurate but with maybe a little more fluidity in the vocals, very slightly more "tubey" than the EF91s but otherwise very similar.

Mullard EF92 large logo - These have been getting the best reviews but I have to say that they are pretty similar to all the other Mullard EF91/EF92s that I have tried.

Mullard EF95 6AK5 - These are a little weaker than the EF92/EF91s. Lighter bass sums it up I think but quite a good sound nonetheless.

Mazda EF91 CV138 6AM6 B7G Pentodes - Now we're talking. These are really cheap on eBay UK. I have no idea who really made these, but it really does say "Mazda" on the tubes. No distortion problems to report. The sound is warm, round and "tubey". Liquid vocals, full bass, rounded smooth highs - very nice. I think these could be my favourite.

Osram W77 9D6 - The most expensive that I bought (around £20). These are vintage from around 1951 I think, and the boxes look even older. These give a very nice sound, a little warmer than the Mullard EF91/EF92s, and less accurate but a very pleasing "tube" sound. This is really what I think the whole point of buying a tube amp is - to get a tube sound...and these provide it. Along with the Mazda's these are my favourite.

This is also my first post and I'm probably not doing it right....but I promise I'll learn!

 

[Testament]

Quote:

Originally Posted by karthur /img/forum/go_quote.gif Thanks to this great forum and the detailed reviews I am now broke, but also now the proud owner of a Little Dot MK III and a whole lot a tubes/valves... Preliminary review, this is based on the tubes being burned-in for no more than a few hours. Headphones: Grado Sr225s. Source: Auzentech X-Meridian with TI Excalibur TLE2072IP Opamp (I'm waiting for my OPA627s to arrive) Russian EF95 6Zh1P-EV Voshod 1974-1978 - I have seen some good reports about these but I don't find them to suit my tastes at all. They give a real vinyl quality to the music (the sound of a cheap record player). The bass is ok not great, but the highs seem harsh and a little tinny. Mullard M8083/CV4014/EF91 small logo - Sound seems quite accurate although with a slight "tubeyness". Good bass, fluid mids, accurate highs, not harsh or smoothed-over. Mullard EF91 M8083/CV4014 large logo - pretty close the small logo ones, can't really tell much of a difference. No distortion problems. Mullard EF92 CV4015 M8161 9D6 KQDDK small logo - Very similar to the EF91s - sound seems quite accurate but with maybe a little more fluidity in the vocals, very slightly more "tubey" than the EF91s but otherwise very similar. Mullard EF92 large logo - These have been getting the best reviews but I have to say that they are pretty similar to all the other Mullard EF91/EF92s that I have tried. Mullard EF95 6AK5 - These are a little weaker than the EF92/EF91s. Lighter bass sums it up I think but quite a good sound nonetheless. Mazda EF91 CV138 6AM6 B7G Pentodes - Now we're talking. These are really cheap on eBay UK. I have no idea who really made these, but it really does say "Mazda" on the tubes. No distortion problems to report. The sound is warm, round and "tubey". Liquid vocals, full bass, rounded smooth highs - very nice. I think these could be my favourite. Osram W77 9D6 - The most expensive that I bought (around £20). These are vintage from around 1951 I think, and the boxes look even older. These give a very nice sound, a little warmer than the Mullard EF91/EF92s, and less accurate but a very pleasing "tube" sound. This is really what I think the whole point of buying a tube amp is - to get a tube sound...and these provide it. Along with the Mazda's these are my favourite. This is also my first post and I'm probably not doing it right....but I promise I'll learn!

I didn't think the mk III was compatible with EF91 family tubes, am I wrong?

 

[karthur]

Quote:

Originally Posted by Testament /img/forum/go_quote.gif I didn't think the mk III was compatible with EF91 family tubes, am I wrong?

Yes you're wrong!

Some people have reported distortion with some EF91s but Little Dot has not been able to replicate the problem in their lab, and I haven't experienced it in any of the EF91s that I reviewed above in my LD MK III.

 

[Testament]

Quote:

Originally Posted by karthur /img/forum/go_quote.gif Yes you're wrong! Some people have reported distortion with some EF91s but Little Dot has not been able to replicate the problem in their lab, and I haven't experienced it in any of the EF91s that I reviewed above in my LD MK III.

sweet, i just pulled the trigger on some mazdas, and am trying to find the osrams now

Edit: So Do you need to mess around with the jumpers for ef91?

 

[Dept_of_Alchemy]

Use the EF92 jumper setting for the EF91 tube family.

The amp was designed to be use with the EF91 tubes initially but some people reported distortion back when the amp was first released, I've never had any problem rolling EF91 tubes and I think the distortion reports are probably due to bad or mis-matched tubes.

- DoA

 

[oofie810]

Quote:

Originally Posted by Dept_of_Alchemy /img/forum/go_quote.gif Use the EF92 jumper setting for the EF91 tube family. The amp was designed to be use with the EF91 tubes initially but some people reported distortion back when the amp was first released, I've never had any problem rolling EF91 tubes and I think the distortion reports are probably due to bad or mis-matched tubes. - DoA

In that case, which tubes from the ef91 family is recommended? I only have the stock and the Russian tubes for my mkIII.