[GotNoRice]

Why do most say to avoid the shorter 6HA5/6HM5 tubes? I got a pair of short Sylvania 6HA5/6HM5 tubes in a combo and so far they don't really sound any worse than the taller Sylvania 6HA5/6HM5 tubes. The only difference that stands out is that the bass with the shorter tubes has a slightly different texture to it (not worse), and it's kind of growing on me.

 

[mordy]

Why do most say to avoid the shorter 6HA5/6HM5 tubes? I got a pair of short Sylvania 6HA5/6HM5 tubes in a combo and so far they don't really sound any worse than the taller Sylvania 6HA5/6HM5 tubes. The only difference that stands out is that the bass with the shorter tubes has a slightly different texture to it (not worse), and it's kind of growing on me.

Perhaps the taller Ei 6HM5 tubes sounded better than the shorter versions?

 

[Cognomen]

Perhaps the taller Ei 6HM5 tubes sounded better than the shorter versions?

My hunch and memory is that a few of the short bottles were tried by a limited number of people who then wrote they preferred the taller version(s). Info here can be subjective - different ears, equipment, music and audio preferences. While many variants of 5654's have been written about here, info about 6HM5's here seems limited with the exception of the Yugo tall bottle which is a solid recommendation and crowd pleaser. I believe it's very possible that if a person collected a bunch of short and tall 6HM5's that they might discover tube(s) that have not been written up much, or at all, that merit a positive review. I have Westinghouse 6HM5's and like them but have not taken time to listen critically to them vs my Yugos. I have read a few times about good experiences with Sylvania tall bottles.

 

[mordy]

My hunch and memory is that a few of the short bottles were tried by a limited number of people who then wrote they preferred the taller version(s). Info here can be subjective - different ears, equipment, music and audio preferences. While many variants of 5654's have been written about here, info about 6HM5's here seems limited with the exception of the Yugo tall bottle which is a solid recommendation and crowd pleaser. I believe it's very possible that if a person collected a bunch of short and tall 6HM5's that they might discover tube(s) that have not been written up much, or at all, that merit a positive review. I have Westinghouse 6HM5's and like them but have not taken time to listen critically to them vs my Yugos. I have read a few times about good experiences with Sylvania tall bottles.

What you say is very plausible. Westinghouse was an old tube manufacturer but had some kind of lawsuit that forbade them from making tubes for a number of years. When they came back into the business some of the tubes were rebranded and there is the possibility that the tubes you mentioned were made by someone else.

 

[kvtaco17]

My hunch and memory is that a few of the short bottles were tried by a limited number of people who then wrote they preferred the taller version(s). Info here can be subjective - different ears, equipment, music and audio preferences. While many variants of 5654's have been written about here, info about 6HM5's here seems limited with the exception of the Yugo tall bottle which is a solid recommendation and crowd pleaser. I believe it's very possible that if a person collected a bunch of short and tall 6HM5's that they might discover tube(s) that have not been written up much, or at all, that merit a positive review. I have Westinghouse 6HM5's and like them but have not taken time to listen critically to them vs my Yugos. I have read a few times about good experiences with Sylvania tall bottles.

Ha! I was one of those people back in 2014, I had issues with the shorties being microphonic in a sample size of 12. The Yugo's on the other hand have been good and are still in service in my 1+ when I don't have one of my crazy tube adapter setups on top of it. I never really explored the other options once I found the Yugo's since they fit what I wanted... perhaps I'll collect a few others and evaluate them if I get bored.

 

[GotNoRice]

info about 6HM5's here seems limited with the exception of the Yugo tall bottle which is a solid recommendation and crowd pleaser. I believe it's very possible that if a person collected a bunch of short and tall 6HM5's that they might discover tube(s) that have not been written up much, or at all, that merit a positive review.

Yeah that makes sense. Going over the thread again, it does seem that most of the comments are in reference to the Yugo tubes. I've never tried those yet, tall or short. I just have a bunch of Sylvania 6HM5/6HA5 tubes right now. I have two sets of "tall" tubes (a set with yellow labels and a set with red labels), and a set of "short" tubes. In the case of the Sylvania tubes, the short tubes seem to hold their own. The tall tube versions are also very good, and there doesn't seem to be any difference between the yellow label and red label versions. The biggest difference compared to 6AK5 tubes is that the Sylvania 6HM5/6HA5 seem to have more bass overall, with the tall tube versions being maybe a bit "boomy" while the short versions have bass that is very very textured (in a good way IMO).

 

[warp2600]

Yeah that makes sense. Going over the thread again, it does seem that most of the comments are in reference to the Yugo tubes. I've never tried those yet, tall or short. I just have a bunch of Sylvania 6HM5/6HA5 tubes right now. I have two sets of "tall" tubes (a set with yellow labels and a set with red labels), and a set of "short" tubes. In the case of the Sylvania tubes, the short tubes seem to hold their own. The tall tube versions are also very good, and there doesn't seem to be any difference between the yellow label and red label versions. The biggest difference compared to 6AK5 tubes is that the Sylvania 6HM5/6HA5 seem to have more bass overall, with the tall tube versions being maybe a bit "boomy" while the short versions have bass that is very very textured (in a good way IMO).

If I remember correctly, the short 6HM5 tubes reviewed in the thread earlier were GE tubes.

 

[rudesssolo]

Hello,

I am a new member here and I own a Little Dot "clone" called "Fosi Audio T20", which is a hybrid tube-digital class D amplifier.

This amplifier is officially compatible with the following tubes: "6J4, 6K4, GE5654, JAN 5654W, 6J1, 6J1P, 6AK5, 6BC5, 403A/B, EF40, EF95, and so on".

I have personally tested it and achieved good results with the following tubes:

- Chinese 6K4 (EF93/6BA6 family)
- Chinese 6J4 (EF94/6AU6 family, stock tubes)
- GE JAN5654W (EF95/6AK5 family)
- Russian 6J1P-EV (EF95/6AK5 family)

Yesterday I received a pair of Mullard CV5377 tubes ("long life" version of CV4014/M8083, EF91/6AM6 family), but unfortunately they don't seem to work properly: they produce very low volume and, when I increase the volume, they distort severely.
The official support could not provide information on whether EF91 family tubes are fully compatible with this amplifier.

Is there anything I can try to make them work?


On another note, I am eagerly awaiting the arrival of the Yugoslavia EI 6HM5 tubes (EC900 family, "long" version), hopefully they will work fine.


Thank you.

 

[Cognomen]

Hello,

I am a new member here and I own a Little Dot "clone" called "Fosi Audio T20", which is a hybrid tube-digital class D amplifier.

This amplifier is officially compatible with the following tubes: "6J4, 6K4, GE5654, JAN 5654W, 6J1, 6J1P, 6AK5, 6BC5, 403A/B, EF40, EF95, and so on".

I have personally tested it and achieved good results with the following tubes:

- Chinese 6K4 (EF93/6BA6 family)
- Chinese 6J4 (EF94/6AU6 family, stock tubes)
- GE JAN5654W (EF95/6AK5 family)
- Russian 6J1P-EV (EF95/6AK5 family)

Yesterday I received a pair of Mullard CV5377 tubes ("long life" version of CV4014/M8083, EF91/6AM6 family), but unfortunately they don't seem to work properly: they produce very low volume and, when I increase the volume, they distort severely.
The official support could not provide information on whether EF91 family tubes are fully compatible with this amplifier.

Is there anything I can try to make them work?


On another note, I am eagerly awaiting the arrival of the Yugoslavia EI 6HM5 tubes (EC900 family, "long" version), hopefully they will work fine.


Thank you.

 

[mordy]

Yeah that makes sense. Going over the thread again, it does seem that most of the comments are in reference to the Yugo tubes. I've never tried those yet, tall or short. I just have a bunch of Sylvania 6HM5/6HA5 tubes right now. I have two sets of "tall" tubes (a set with yellow labels and a set with red labels), and a set of "short" tubes. In the case of the Sylvania tubes, the short tubes seem to hold their own. The tall tube versions are also very good, and there doesn't seem to be any difference between the yellow label and red label versions. The biggest difference compared to 6AK5 tubes is that the Sylvania 6HM5/6HA5 seem to have more bass overall, with the tall tube versions being maybe a bit "boomy" while the short versions have bass that is very very textured (in a good way IMO).

You may want to try the Yugoslavian Ei 6HM5 - they are not expensive and perhaps better sounding than the Sylvania.

 

[D1N0]

Hello,

I am a new member here and I own a Little Dot "clone" called "Fosi Audio T20", which is a hybrid tube-digital class D amplifier.

This amplifier is officially compatible with the following tubes: "6J4, 6K4, GE5654, JAN 5654W, 6J1, 6J1P, 6AK5, 6BC5, 403A/B, EF40, EF95, and so on".

I have personally tested it and achieved good results with the following tubes:

- Chinese 6K4 (EF93/6BA6 family)
- Chinese 6J4 (EF94/6AU6 family, stock tubes)
- GE JAN5654W (EF95/6AK5 family)
- Russian 6J1P-EV (EF95/6AK5 family)

Yesterday I received a pair of Mullard CV5377 tubes ("long life" version of CV4014/M8083, EF91/6AM6 family), but unfortunately they don't seem to work properly: they produce very low volume and, when I increase the volume, they distort severely.
The official support could not provide information on whether EF91 family tubes are fully compatible with this amplifier.

Is there anything I can try to make them work?


On another note, I am eagerly awaiting the arrival of the Yugoslavia EI 6HM5 tubes (EC900 family, "long" version), hopefully they will work fine.


Thank you.

I don't think EF91 tubes are compatible with Fosi. I look up 6h5n. It seems to be a 9 pin tube, so it won't fit the 7 pin sockets in the fosi.

 

[barbazz]

EF95 and EF91 have different pinouts. We are lucky enough to have a jumper that can make LD 1+ compatible with both families. Not sure if Fosi have something similar.

 

[D1N0]

Not sure if Fosi have something similar.

Nope. Maybe you could make some kind of adapter.

 

[warp2600]

I don't think EF91 tubes are compatible with Fosi. I look up 6h5n. It seems to be a 9 pin tube, so it won't fit the 7 pin sockets in the fosi.

Why did you look up 6h5n? Nobody mentioned that tube.

 

[rudesssolo]

At page 59 of this thread, the user Audiofanboy wrote this:

"Note that for EF92/91 tubes, one could also imagine placing a small wire between pins 6 and 7 to strap grid 2, grid 3 and anode together by hand and stay in the 6AK5 jumper setting all the time -if you really hate jumpers that much."

Is that a way to use EF91/92 tubes in EF95 mode?

If yes, would the red line I've drawn be the correct way to join pins 6 and 7?