[CAJames]

Unfortunately the 7n7's do not sound very good in my Incubus amps, @bcowen will attest to this, they sound much better in other amps. I designed my amps to have very little in the signal paths that might color or inhibit the sound of the tubes. That is my opinion of the outcome as well as 100 or so people who have heard the amp.

Bill kept wondering why I was not impressed, and why we did not include the 7n7 in with the 52 included in our blind listening, then he knew why after I gave him an amp. I suppose some manufacturers are trying to emulate solid state, I have a few amps where you cannot detect much difference. They have an accuracy but lack the warmth and depth of a great tube amp.

Interesting. Do 7N7s sound different than the same version of 6SN7, e.g. octal and loctal versions of the Sylvania XXX-GTA?If anything the math suggests loctal should sound better, everything else being equal. Which it never is.

 

[Paladin79]

Interesting. Do 7N7s sound different than the same version of 6SN7, e.g. octal and loctal versions of the Sylvania XXX-GTA?If anything the math suggests loctal should sound better, everything else being equal. Which it never is.

I will have locate the octal version and give them a listen. I should not say they sound bad, just not as exceptional as other tubes IMHO. I believe Bill put it, my amp makes tubes sound 100 compared to 50 compared to 60 compared to 50 in other amps. I hope that makes sense and I beg Bill’s pardon if I misquoted him. I know we have a Bad Boy and maybe a VT-231 represented but I have never considered loktal equivalents.

It is also best to mention a group of five is doing the tube selection for the blind listening so it is their decision which tubes to include. In the test group are GEC, Marconi, some well regarded Tung Sol, Mullard, Brimar, RCA, Hytron etc. You can place a price on those tubes but there is at least one, maybe two that are unique prototypes, never put up for sale. This is why blind listening is done, I received one of those tubes in a Pelican case and knew what it was and its history. It is not always easy to be objective unless you go by sound alone.

 

[attmci]

The "best" tube for your amp will depend on your chain of equipments (DAC, Headphones,plus more) and how your ears judge the tube's ability to reproduce music.

 

[Paladin79]

The "best" tube for your amp will depend on your chain of equipments (DAC, Headphones,plus more) and how your ears judge the tube's ability to reproduce music.

That is part of it, but then I build amps.

I own at least five DAC's, 7 or 8 headphones and while I have modified some amps to fit friends needs certainly some tubes sound better than others. My testing with some local friends will mean fifty people will use the same Sennheiser headphones, 4 pairs, HD 800. Several DAC's were tried but the group favorite of twenty we tried is the Aqua La Voce S3. Those DAC's went through the same test cycle that we are using for tubes.

As far as home use, sure if you own say a Lyr 3 and the new Bifrost your results would be different. (I have those devices and I am hard pressed to tell a difference in some tubes using the same music my group uses.)

If you pay $250 for a tube, then try it in your home amp there can be some expectation bias. Or maybe all your friends say a particular tube is the best they have ever heard, how does one stay impartial?

In my group test, we are careful to keep all things as close to the same as possible and we only switch between four tubes at any one time.With the scoring system and blind listening, and a large enough group it is not just one person's opinion. Price does not matter, or brand name or any one person's preferences.

Having done this with equipment before, it is kind of fun to see a $500 DAC rate higher than some going for several thousand dollars. If we find a tube that goes for $20 to be in the top five, and ranks ahead of many going for $250 -$2000 that would certainly be interesting.

I designed my amp to be as tube revealing as I could get it, and so far out of 100 listeners, one person did not hear a great deal of difference between tubes and he was pretty new to headphones, tubes, and headphone amps. This sounds a bit clinical I bet but my friends seem to love the musicality of the amp and I was a little shocked by that but yet, most of us do like tubes over transistors for a reason.

 

[RoyGB]

Hi yall,
I'm coming over from the Project Ember Tube Rolling thread. Ember is a 48V plate starved tube hybrid so it is a bit of a different beast in terms of how it is dealing with its tubes.

I have been rolling a lot of 6J5 and 76 series tubes recently and have been enjoying some of them a lot.

I definitely feel like the 76 tubes should be thrown into the lot with the 6J5 series considering they were the predecessor tubes of the 6P5 and 6C5.

These are my current favorite tubes. Tung Sol 76's Lot's of tube character, warm, lush, with good dynamics.

I was also a really big fan of Hytron 6C5's. But my pair has a pretty bad gain imbalance so I really don't use them. I've been searching for another pair for a while now but I have had no luck finding any. I don't think a properly matched pair for sale exists on the internet at this moment in time. The closest I can find is an ebay listing with two different construction tubes.

I have a bunch more pairs that I can write impressions on in the upcoming days. Sometimes these writeups take some time.

 

[leftside]

Hi yall,
I'm coming over from the Project Ember Tube Rolling thread. Ember is a 48V plate starved tube hybrid so it is a bit of a different beast in terms of how it is dealing with its tubes.

I have been rolling a lot of 6J5 and 76 series tubes recently and have been enjoying some of them a lot.

I definitely feel like the 76 tubes should be thrown into the lot with the 6J5 series considering they were the predecessor tub

I'll post up some pics and thoughts of the 76 tubes that I have over the next few days. I've acquired quite a few Fivre 76 recently. I find the 76 tube to be very similar to the 6C5. Airy and refined.

 

[L0rdGwyn]

Something I find interesting is the evolution of these tubes.

The 76 being the precursor to the 6P5, it is then cited as the progenitor to subsequent tubes like the 6C5 and 6J5, but I'm not so sure.

The L63 has its own parent, the Marconi-Osram MHL4, which is actually much more similar in terms of specification to the 6J5 / L63 and existed before the 76 (the MHL4 was first in production in 1930, whereas the 76 was first made in 1933). I wonder if there was a parallel evolution, or perhaps just a similar need for tubes of this spec at the time.

Here are the specs of the respective tubes from their sheets, in chronological order of first production from what I have been able to find.

MHL4 (1930): μ 20; ra 8000; gm 2500 μmhos
76 (1933): μ 13.8; ra 9500; gm 1450 μmhos
6C5G (1936): μ 20; ra 10000; gm 2000 μmhos
6J5G (1936): μ 20; ra 7700; gm 2600 μmhos
6P5G (1938): μ 13.8; ra 9500; gm 1450 μmhos

An aside, the earliest date I have found for the 6P5G is 1938. Since it is equivalent to the 76 albeit with an octal base, I assume the 76 was used in its place until then, so it isn't necessarily a precursor to the 6C5 / 6J5, more like a replacement for the 76.

Looking at the specs, you can see the MHL4 is nearly an exact 6J5 equivalent, however with 4V 1A heaters and a lower grid voltage required. Its electrical characteristics are much more similar to the 6J5 than the 76, so who is the real parent? Most likely getting to the same result via different paths, just some food for thought

 

[RoyGB]

Something I find interesting is the evolution of these tubes.

The 76 being the precursor to the 6P5, it is then cited as the progenitor to subsequent tubes like the 6C5 and 6J5, but I'm not so sure.

The L63 has its own parent, the Marconi-Osram MHL4, which is actually much more similar in terms of specification to the 6J5 / L63 and existed before the 76 (the MHL4 was first in production in 1930, whereas the 76 was first made in 1933). I wonder if there was a parallel evolution, or perhaps just a similar need for tubes of this spec at the time.

Here are the specs of the respective tubes from their sheets, in chronological order of first production from what I have been able to find.

MHL4 (1930): μ 20; ra 8000; gm 2500 μmhos
76 (1933): μ 13.8; ra 9500; gm 1450 μmhos
6C5G (1936): μ 20; ra 10000; gm 2000 μmhos
6J5G (1936): μ 20; ra 7700; gm 2600 μmhos
6P5G (1938): μ 13.8; ra 9500; gm 1450 μmhos

An aside, the earliest date I have found for the 6P5G is 1938. Since it is equivalent to the 76 albeit with an octal base, I assume the 76 was used in its place until then, so it isn't necessarily a precursor to the 6C5 / 6J5, more like a replacement for the 76.

Looking at the specs, you can see the MHL4 is nearly an exact 6J5 equivalent, however with 4V 1A heaters and a lower grid voltage required. Its electrical characteristics are much more similar to the 6J5 than the 76, so who is the real parent? Most likely getting to the same result via different paths, just some food for thought

I think the biggest hurdle in including them is going to be the electrical requirements to run them. Considering this is somewhat of a tube rolling thread, it is going to be hard getting any representation for them because you cant just adapt into a 6SN7 socket. Likewise, I wouldn't lot in 56 tubes with 76 tubes even though 56 tubes were the precursor, due to their own wonky electrical requirements (2.5V 1A).

 

[Paladin79]

I think the biggest hurdle in including them is going to be the electrical requirements to run them. Considering this is somewhat of a tube rolling thread, it is going to be hard getting any representation for them because you cant just adapt into a 6SN7 socket. Likewise, I wouldn't lot in 56 tubes with 76 tubes even though 56 tubes were the precursor, due to their own wonky electrical requirements (2.5V 1A).

Luckily on some amps like the Vali 2, the designer is there to ask. It will handle the filament current requirements of a 6sn7, even though it was made for a 6922.

 

[L0rdGwyn]

I think the biggest hurdle in including them is going to be the electrical requirements to run them. Considering this is somewhat of a tube rolling thread, it is going to be hard getting any representation for them because you cant just adapt into a 6SN7 socket. Likewise, I wouldn't lot in 56 tubes with 76 tubes even though 56 tubes were the precursor, due to their own wonky electrical requirements (2.5V 1A).

Oh I'm sorry, I wasn't suggesting they be included, although I could be their representative, just sharing some information on the origin of the 6J5 I thought others might find interesting, my mistake.

 

[chrisdrop]

Oh I'm sorry, I wasn't suggesting they be included, although I could be their representative, just sharing some information on the origin of the 6J5 I thought others might find interesting, my mistake.

Certainly interesting.
Tx for sharing.

 

[RoyGB]

Luckily on some amps like the Vali 2, the designer is there to ask. It will handle the filament current requirements of a 6sn7, even though it was made for a 6922.

Vali likely wont be able to do any tube other than a 6V, and most amps using tubes like these are using them as preamp tubes and don't have nearly enough current to drive two 1A+ tubes. Most people running anything like the aforementioned usually require external power supplies to handle all the power requirements of the tube.

 

[whirlwind]

Something I find interesting is the evolution of these tubes.

The 76 being the precursor to the 6P5, it is then cited as the progenitor to subsequent tubes like the 6C5 and 6J5, but I'm not so sure.

The L63 has its own parent, the Marconi-Osram MHL4, which is actually much more similar in terms of specification to the 6J5 / L63 and existed before the 76 (the MHL4 was first in production in 1930, whereas the 76 was first made in 1933). I wonder if there was a parallel evolution, or perhaps just a similar need for tubes of this spec at the time.

Here are the specs of the respective tubes from their sheets, in chronological order of first production from what I have been able to find.

MHL4 (1930): μ 20; ra 8000; gm 2500 μmhos
76 (1933): μ 13.8; ra 9500; gm 1450 μmhos
6C5G (1936): μ 20; ra 10000; gm 2000 μmhos
6J5G (1936): μ 20; ra 7700; gm 2600 μmhos
6P5G (1938): μ 13.8; ra 9500; gm 1450 μmhos

An aside, the earliest date I have found for the 6P5G is 1938. Since it is equivalent to the 76 albeit with an octal base, I assume the 76 was used in its place until then, so it isn't necessarily a precursor to the 6C5 / 6J5, more like a replacement for the 76.

Looking at the specs, you can see the MHL4 is nearly an exact 6J5 equivalent, however with 4V 1A heaters and a lower grid voltage required. Its electrical characteristics are much more similar to the 6J5 than the 76, so who is the real parent? Most likely getting to the same result via different paths, just some food for thought

Interesting, great find!

 

[Paladin79]

Vali likely wont be able to do any tube other than a 6V, and most amps using tubes like these are using them as preamp tubes and don't have nearly enough current to drive two 1A+ tubes. Most people running anything like the aforementioned usually require external power supplies to handle all the power requirements of the tube.

I only said it could do a 6sn7, and I double checked it with Jason at Schiit before doing that. I studied tube theory in college so I might know a little about them. I was also the first person to get a Coaster amp working, mini Vali, outside of Schiit. I caught a mistake in the schematic and BOM.

I even made one into a snow globe, a flying saucer, and mounted one in an 8 ball. I never could get the glass cutting down well enough to mount one in a scotch bottle, but I tried.

 

[RoyGB]

Alright, I figure I might be the one to introduce these tubes to this thread as well as share some words of advice before you all go out and snatch up every last one of these.

These are know as 'Magic Eye' tubes. And some of them share the same electrical characteristics (or close enough) as the 6J5 tubes and the same pin base.

PLEASE DON'T BUY THESE TUBES

I know, I know. They are really cool and I am sure you all want a pair. So a couple reasons why I don't suggest you go out and buy them.

1. It is uncertain whether or not these would actually work as a preamp tube or allow audio to even get through them. When I first stumbled upon these tubes I wanted to buy a pair because they were the coolest tubes I had seen. The moving bands can be used as a level or VU meter for audio. After much digging to see if they would actually work as audio tubes results were inconclusive. It is a solid maybe. Maybe someone else has some info on these but a maybe was as far as I was able to get. Quite frankly I don't want to know as I detail below why.
2. These tubes are not for us. One of the main purposes of magic eye tubes is to be used to tune radios. Their main purpose was to tune radios. The antique radio repair community relies on these tubes as tuning indicators for their radios, and supply is only ever going down. Nobody makes these anymore.
3. The lifespan on these tubes is in the mid to low hundreds of hours (300-500). This goes hand in hand with my prior point. A lot of people end up building in separate switches to turn these tubes off as soon as possible after their radios are tuned to save life on these tubes.

We enjoy our vintage audio tubes. Let the radio guys keep their radio tubes.
Who knows how much longer relics like this may be able to be used and enjoyed by their respective community.