[Cognomen]

6N6P or 6H30pi work fine.

(I have Electro-Harmonix 6H30pi that I bought new. The information printed on them is so faint that it is barely legible.)

 

[jsk ksj]

6N6P are much cheaper. I only paid £140 for the amp so don't want to pay too much.

 

[mordy]

Thanks. I expect I need a matched pair?

You do not need a matched pair - another myth to enable sellers to charge more. (Only certain less common amp designs need matched pairs.)

 

[jsk ksj]

Ok, thanks for the heads up

 

[Cognomen]

Thanks. I expect I need a matched pair?

Thanks. I expect I need a matched pair?

Cosmetically matched pairs should result in the same tube sound on both channels A cosmetic pair has the same internals including the getter. The information on the tube such as font and color of printing and so on are the exact same. If present, an exception can be date codes. 6N6P sometimes have date codes such as VII 79 meaning July, 1979. The closer the date codes the better. Due to the circuitry in the Little Dot one does not need to pay extra for tube-tester electronically matched tubes. There are also cryo cold treated tubes and tube damper rings. Some people find they sound better, while many consider them snake oil. If you ask the vendor for a cosmetic pair and provide info such as above, they are likely to send a cosmetically-matched pair. Sometimes the eBay Ukraine 6N6P vendors have crates chock full of cosmetically matched tubes that they are selling one by one or in pairs. I have had excellent experiences buying from Ukraine. The shipping can take weeks, though.

 

[jsk ksj]

Cosmetically matched pairs should result in the same tube sound on both channels A cosmetic pair has the same internals including the getter. The information on the tube such as font and color of printing and so on are the exact same. If present, an exception can be date codes. 6N6P sometimes have date codes such as VII 79 meaning July, 1979. The closer the date codes the better. Due to the circuitry in the Little Dot one does not need to pay extra for tube-tester electronically matched tubes. There are also cryo cold treated tubes and tube damper rings. Some people find they sound better, while many consider them snake oil. If you ask the vendor for a cosmetic pair and provide info such as above, they are likely to send a cosmetically-matched pair. Sometimes the eBay Ukraine 6N6P vendors have crates chock full of cosmetically matched tubes that they are selling one by one or in pairs. I have had excellent experiences buying from Ukraine. The shipping can take weeks, though.

I have just ordered these from eBay/ Ukraine.

 

[Cognomen]

6N6P are much cheaper. I only paid £140 for the amp so don't want to pay too much.

(If it's hard to see what is written on the power tubes that came with it, you might already have Electro Harmonix 6N30pi which Little Dot included as stock tubes at one point when selling the MkIV.)

 

[jsk ksj]

(If it's hard to see what is written on the power tubes that came with it, you might already have Electro Harmonix 6N30pi which Little Dot included as stock tubes at one point when selling the MkIV.)

I have taken a closer look at the tubes. They are the 6H30pi.

If only 1tube has blown, and I don't need matched pairs, can I just buy 1 replacement 6H30pi? Are they all the same? I have seen single tubes selling for £35.

 

[Cognomen]

I have taken a closer look at the tubes. They are the 6H30pi.

If only 1tube has blown, and I don't need matched pairs, can I just buy 1 replacement 6H30pi? Are they all the same? I have seen single tubes selling for £35.

My hunch is Yes, it is very likely the new one would be the same sounding provided it is the same brand and things printed on the tube are the same and if production dates are close. They are made by Electro Harmonix and Sovtek. The farther apart the production dates, the higher the risk they tweaked the manufacturing line which may result (or not so much) in different sound.

My best w.a.g. (wild a _ _ ahem guess) is that what follows might not apply to the 6H30pi. Sometimes when looking for cosmetically matched tubes likely to sound the same, matching becomes detailed such as the same code for the factory where it was manufactured. I can't see one on my Electro harmonix tubes so perhaps they are all the same factory. One also wants to match internals which very often includes the getter. The getter is typically the metal structure near the top of the tube near the silvery coating. In the case of my Electro-Harmonix it looks like an upside down dinner plate attached by two wires. For some tubes getters change over time and they can have a tremendous influence on the value of the tube. People also match other internals such as shields and their color/composition. My electro harmonix also have gold pins - people also match pins. Often old tubes were rebranded by resellers. They tend to have a code on them for that. For example RCA did not necessarily make all of the tubes it sold under its brand. There will probably be a code on an old RCA tube if it was made by another company. If I have a single tube and it was complicated due to all the above minutiae etc, in my experience, it can be difficult to find a match even though some vendors are willing to receive photos and try to match it. My hunch is that it is not complicated for the Electro Harmonix 6H30Pi, though. All of the above details explain why some people tend to want as close as possible detailed cosmetic matches of the internals and everything printed on an old tube...

If a vendor is displaying tube tester data that seems similar for tubes, they are touting the tubes as electronically matched. Little Dot and technical folks here say it won't make a difference due to Little Dot's circuitry. If a vendor offers the option of tube testing to electronically match tubes, it is probably not worth paying extra for it for the Little Dot. It's good if they test, however, to make sure the tube does not have shorts and works. Good vendors do that for free and warrant their tubes will work.

 

[jsk ksj]

So, the little dot should even out small difference between tubes of the same type?

Imbalance update: it's becoming worse by the day. One of the tubes is definitely on its way out.

I have ordered a single 6H30pi replacement tube for £35. Fingers crossed it sorts issue out.

 

[triod750]

A small difference between left and right tube is probably smaller than your normal difference in hearing between left and right ear. I think very few people have the same frequency response in both ears. Mostly the brain sorts these things out.

 

[jsk ksj]

A small difference between left and right tube is probably smaller than your normal difference in hearing between left and right ear. I think very few people have the same frequency response in both ears. Mostly the brain sorts these things out.

The difference in volume is extremely noticeable. This has only happened in the last week. I swap the tubes over, the imbalance changes side. To correct it I am having to use about half the total available balance adjustment on Uapp.

 

[triod750]

I don't mean your pair now, I mean when you get another tube,making a new pair. Obviously there is something wrong now, whatever it might be.

 

[jsk ksj]

I don't mean your pair now, I mean when you get another tube,making a new pair. Obviously there is something wrong now, whatever it might be.

Thanks for the clarification.

I believe that you own a mk4. What have been your most successful (bang for the buck) tube rolling history with it ?

 

[triod750]

Thanks for the clarification.

I believe that you own a mk4. What have been your most successful (bang for the buck) tube rolling history with it ?

I've got to think before I answer this. If I don't think I would say KenRad 6C5 in adapters from @Deyan. In the same adapters you can use 6J5. These are 'metal tubes' and much cheaper than the all glass versions (6C5GT and 6J5GT, often with and added /G as in 6J5GT/G). C5/J5 are glass tubes inside the metal. I haven't yet tried the Russian equivalent 6C2C/6S2S that is said to be very good and much cheaper. These are all input tubes (in the front).

I have tried very many combinations indeed. It's more a matter of different good than better. Sometimes you find the best combination and this impression will last until you listen to different music.

If I had to use just one combination with native transformer (no external PSU) it would be EL42 with Melz 6N12S. Unfortunately these Melz have become very expensive and always were in very short supply. Another good alternative as output tubes is either 5687 or E182CC. These use the same adapter. I bought mine from xulingmrs before I became aware of @Deyan.

Other people have other favourites and rightly so