Little Dot Tube Amps: Vacuum Tube Rolling Guide
Oct 16, 2021 at 6:44 PM Post #12,766 of 12,798

triod750

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My Little Dot MKIVSE was delivered with EH 6N30Pi as output tubes. I listened to them for a while before starting my tube rolling journey. I have posted just a little about it. Tonight I revisited these 6N30Pi with 6J5GT/G in adapters to the 6AK5 input sockets. They were like I remembered them, a little anemic. It's like looking at a picture with few pixels - you see the picture but there is a lot missing. I pulled out other tubes to compare them to, without using external power supply. I chose the dual triode 5687 that is electrically close to E182CC and Melz 6N12S but more available and thus cheaper. American tube manufacturers made loads of them and they are good quality tubes. With this tube the picture has a lot more pixels. I can see it much better with less strain. They also need adapters but are well worth it - in my opinion. They are not my best tubes but might be best value for money, at least for me. But I rarely use them.
 
Oct 16, 2021 at 7:20 PM Post #12,767 of 12,798

triod750

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For input tubes I have used the common ones up to 6HM5 and C3g. With adapters but without external power supply I have used C3g but also EL42 and 6J5 types and 6C5 types. With external power supply and adapters I have also used different dual triodes as 6N7, 6SN7/6N8S, 12AU7/ECC82, 12AT7/ECC81/6201, E80CC, 6F8G and probably one or two other tubes.

For output tubes I have used 6N6P variants, 6N30Pi, different 6SN7GT, 6F8G, 5687, 6N8S, 6N12S, these without external psu and 6BX7GT, 6BL7GT, A2293 (half a 6AS7G so two per channel), 6080, 6AS7G, 6N13S and, and, and...don't remember but these latter tubes with external psu and adapters.

As you can understand there are a lot of possible combinations to tailor the sound of our small dots. I don't use 6080 or 6AS7G on a regular basis. They produce a lot of heat and I don't expect our dots to be able to take that in the long run. The very powerful 2 x A2293 per channel runs a lot cooler in spite of being equal to one 6080 or 6AS7G.

I have some favourite combinations that suit my mood and the music I play. I use a pair of Sennheiser HD-650 with a Zu Mobius cable and a Beresford Caiman SEG dac with Dorado psu enhancer and only play cd. I have enjoyed my experiments and still do and have some new adapters and tubes on their way to me. A sensible thing to do would be to put your money in a 'better' amp but that would be boooring. Just imagine how much I have experienced and learnt! And if I eventually want another amp I probably have a lot of good tubes for it already. But as for now the journey continues.
 
Oct 16, 2021 at 10:10 PM Post #12,768 of 12,798

mordy

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For input tubes I have used the common ones up to 6HM5 and C3g. With adapters but without external power supply I have used C3g but also EL42 and 6J5 types and 6C5 types. With external power supply and adapters I have also used different dual triodes as 6N7, 6SN7/6N8S, 12AU7/ECC82, 12AT7/ECC81/6201, E80CC, 6F8G and probably one or two other tubes.

For output tubes I have used 6N6P variants, 6N30Pi, different 6SN7GT, 6F8G, 5687, 6N8S, 6N12S, these without external psu and 6BX7GT, 6BL7GT, A2293 (half a 6AS7G so two per channel), 6080, 6AS7G, 6N13S and, and, and...don't remember but these latter tubes with external psu and adapters.

As you can understand there are a lot of possible combinations to tailor the sound of our small dots. I don't use 6080 or 6AS7G on a regular basis. They produce a lot of heat and I don't expect our dots to be able to take that in the long run. The very powerful 2 x A2293 per channel runs a lot cooler in spite of being equal to one 6080 or 6AS7G.

I have some favourite combinations that suit my mood and the music I play. I use a pair of Sennheiser HD-650 with a Zu Mobius cable and a Beresford Caiman SEG dac with Dorado psu enhancer and only play cd. I have enjoyed my experiments and still do and have some new adapters and tubes on their way to me. A sensible thing to do would be to put your money in a 'better' amp but that would be boooring. Just imagine how much I have experienced and learnt! And if I eventually want another amp I probably have a lot of good tubes for it already. But as for now the journey continues.
I don't think an upgraded amp would be boring....
Many of the things that you have learned using your Little Dot MKIV SE will apply to other amps as well. As a previous owner of the Little Dot MKIII and having expiremented quite a lot with it I can tell you that no matter what tube combination you try, the amp has inherent limitiations as how far you can improve the sound.
In order to take proper advantage of the possibilities that tube rolling offers with all the tubes you already own, you will need a more capable amp.
And if you decide to upgrade you are going to realize the sizeable improvements in sound - there is no turning back.
 
Oct 17, 2021 at 11:16 AM Post #12,769 of 12,798

triod750

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I don't think an upgraded amp would be boring....
The amp in itself would not be boring, I agree on that. But my intention was to explore how far I could take this Little Dot. I have enjoyed the ride very much and so far I can not see 'the end'. But if the better amp would be the end, well, I'm not sure I would be satisfied by that. And even with a better amp there are even better amps out there. So you have to stop somewhere. I don't know whether a lot of people have listened to 6BX7 or A2293 with really good input tubes in Little Dot and know how this perform. I am sure there are amps designed for these tubes where they might sound even better but 'better' is a personal thing.

Eventually I might end up with a more capable amp - I probably will - but if I won't, I won't lose any sleep due to this. I enjoy my music and I enjoy my experiments. I have listened to a lot of capable loudspeaker amps, and own one or two, so I know what is possible in sound reproduction. I'm feeling good!
 
Oct 18, 2021 at 7:19 PM Post #12,770 of 12,798

triod750

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Right now I am listening to Arvo Pärt 'Summa' with 6J5GT/G as input (Brimar branded but Ken-Rad manufactured) and Brimar 6SN7GT as output. It feels as if it would be impossible to make it sound better. I know this is totally wrong but it is how it feels. And the 5687 I listened to the other day are too powerful for this kind of music. The music right now is engaging, involving and relaxed.

(I use the input tubes with adapters and with the amps own transformer. I use the output tubes with adapters and although I can use them with the amps own transformer I use the external psu since it seems to give the output tube just a little more sound quality. This might be my imagination though).

If my memory serves me, I paid EUR26 for the tubes.
 
Oct 18, 2021 at 9:04 PM Post #12,771 of 12,798

mordy

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Right now I am listening to Arvo Pärt 'Summa' with 6J5GT/G as input (Brimar branded but Ken-Rad manufactured) and Brimar 6SN7GT as output. It feels as if it would be impossible to make it sound better. I know this is totally wrong but it is how it feels. And the 5687 I listened to the other day are too powerful for this kind of music. The music right now is engaging, involving and relaxed.

(I use the input tubes with adapters and with the amps own transformer. I use the output tubes with adapters and although I can use them with the amps own transformer I use the external psu since it seems to give the output tube just a little more sound quality. This might be my imagination though).

If my memory serves me, I paid EUR26 for the tubes.
Yes, those prices were yesterday in time. A pair of Brimar 6SN7GT will set you back around $300 today...
I have been playing with tube amps for around twelve years now and it is really amazing how much the prices have gone up.
 
Oct 19, 2021 at 7:08 AM Post #12,772 of 12,798

triod750

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Yes, those prices were yesterday in time. A pair of Brimar 6SN7GT will set you back around $300 today...
I have been playing with tube amps for around twelve years now and it is really amazing how much the prices have gone up.
I think I bought these Brimar 6SN7GT two years ago and the 6J5GT/G early this year. But you are right, I could have found much more expensive siblings). I have an audio friend that has taught me to have patience when looking for tubes. 'Eventually something good will turn up'. His name is mordy :).
 
Oct 19, 2021 at 7:53 AM Post #12,774 of 12,798

Khitzi

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Does anyone have any recommendations for power tubes on the Little Dot MK II?
 
Oct 19, 2021 at 12:58 PM Post #12,776 of 12,798

Khitzi

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What sound qualities do you want from them? I am not familiar with MKII - what are the standard tubes for input and output?
To be honest, I'm just looking for some general recommendations of where to start. I love the list on page 1 of this thread, but there's no info for the power tubes. This is my first tube amp so I'm just enjoying trying new tubes out.

I'm using HD 800S, which I love for detail and soundstage. So I look for the tubes to add just a bit of body and warmth, but not so much that I lose lots of detail. Currently using some Mullard EF95 M8100 Ring Getter driver tubes, and they've warmed up the signature quite nicely. Just wondering what I can do with the stock power tubes now to see if I can improve it at all.

The stock power tube is 2x 6N6 - came with some cheap Chinese ones as standard.
 
Oct 19, 2021 at 1:19 PM Post #12,777 of 12,798

triod750

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To be honest, I'm just looking for some general recommendations of where to start. I love the list on page 1 of this thread, but there's no info for the power tubes. This is my first tube amp so I'm just enjoying trying new tubes out.

I'm using HD 800S, which I love for detail and soundstage. So I look for the tubes to add just a bit of body and warmth, but not so much that I lose lots of detail. Currently using some Mullard EF95 M8100 Ring Getter driver tubes, and they've warmed up the signature quite nicely. Just wondering what I can do with the stock power tubes now to see if I can improve it at all.

The stock power tube is 2x 6N6 - came with some cheap Chinese ones as standard.
I would recommend a pair of 5687 as an alternative to 6N6P. To me they give a bit more flesh to the sound. They need adapters. You can get them from that bay or from Deyan, I suppose. There are other alternatives but this is where I wish that I had started myself. In the same adapters you can use E182CC that Little Dot originally was designed for and delivered with a long time ago. These tubes have become very expensive and I haven't tried them myself since I took another path.
Mind you, we all have different ears so I leave no guarantee. If you become disappointed you could punish me by sending me your 800S. Just a suggestion :).
 
Oct 19, 2021 at 7:00 PM Post #12,778 of 12,798

triod750

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Right now I listen to my Little Dot MKIVSE without external PSU. For input I use a pair of 6C5G, One of them arrived today and sounds good from the start. It is a BU version to some people:

3977447


It has a metal shield cover to prevent hum. This is soldered to pin number one (m). I could remove it but I won't. (BU means Butt Ugly. It could also mean BeaUtiful).

In the other channel is another 6C5G without such cover. I have used it for a while and it is beginning to sound good. It looks similar to this:

iu

and there is no markings other than 6C5G. But the sound is there.

For outputs i use a Soviet near equivalent to 5687 that isn't very common and has become expensive; Melz 6N12S. This combination has taken me far from the original tubes in my amp. Today I would not recommend people to look for 6N12S when 5687 is available for much less. And to my ears, my 6J5GT/G pairs somewhat better with 5687 than these 6C5G. But 6C5 and 6J5 use the same adapter and can be had cheapish in different versions.

I have just tried a few different tubes from the 6C5 and 6J5 families and don't have any strong opinions. But I have fun.
 
Oct 20, 2021 at 10:51 AM Post #12,779 of 12,798

TrollDragon

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To be honest, I'm just looking for some general recommendations of where to start. I love the list on page 1 of this thread, but there's no info for the power tubes. This is my first tube amp so I'm just enjoying trying new tubes out.

I'm using HD 800S, which I love for detail and soundstage. So I look for the tubes to add just a bit of body and warmth, but not so much that I lose lots of detail. Currently using some Mullard EF95 M8100 Ring Getter driver tubes, and they've warmed up the signature quite nicely. Just wondering what I can do with the stock power tubes now to see if I can improve it at all.

The stock power tube is 2x 6N6 - came with some cheap Chinese ones as standard.
The first part of the table on page 585 shows output tubes that we can use, some need external power supplies and most need adapters. The eBay links in the table to the Powersocket adapters are long since dead, but there are other adapters available.
https://www.head-fi.org/threads/lit...e-rolling-guide.563884/page-585#post-11155053
 
Oct 28, 2021 at 5:54 PM Post #12,780 of 12,798

triod750

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Our Italian member @lupoal discussed the importance of correct heater voltage previously. I found this quote on this site tonight: .http://www.emissionlabs.com/datasheets/EML300B-25V.html

"Heater Voltage: Some people experiment with lower filament voltage, to expect better lifetime. This is essentially wrong to do. If the magic was that easy, we would make the tubes like this ourselves. Under Heating can lead to early loss of emission, though new EML tubes will fully recover once the heater voltage is corrected, older tubes will recover only partially. The specified filament voltage at 0% tolerance is the one for best lifetime. The voltage we specify, is at the TUBE PINS itself. Any voltage drop by the socket contacts must be compensated for. For 2A3 tubes, some sockets have 50mV voltage drop per pin, because the heater current of 2.5 Ampere is very high. Causing a total drop of 0.1V for both pins together. So a voltage of 2.6Volts at the socket pins is needed, to make sure there is 2.5 Volts at the tube pins".

I have nothing to add to this due to lack of knowledge and experience. I don't know the magnitude of loss of lifetime, if so.
 

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