5751 - wich is the best alternative to this tube ?

[kagliostro]

Tubenit in his project often uses 5751 tubes

I'm not able to find it at hamfest flea market

which is the best alternative to the use of this tube ?

Thanks

Kagliostro

[Geezer]

5751 are just slightly lower mu/gain than a 12AX7, so 12AX7 is the logical sub (maybe bias it a bit cooler for lower gain).
12AT7 would have a slightly lower mu than the 5751, so that is another choice.....

G

[kagliostro]

Thanks Geezer

so the best alternatives are:

a new 12ax7 biased a bit cooler

or an used 12ax7

or a new 12at7

Kagliostro

[tubeswell]

Thanks Geezer

so the best alternatives are:

a new 12ax7 biased a bit cooler

or an used 12ax7

or a new 12at7

Kagliostro

a 5751 is pretty similar to a 12AX7, albeit with slightly less amplification factor. Whereas a 12AT7 is a different beast altogether. I found this article by Old Tele Man very instructive in this regard.

[John]

Tubeswell, thanks for that article!

[kagliostro]

Many thanks

Kagliostro

[tubenit]

Tubenit in his project often uses 5751 tubes

I've never gotten the same sweet musical tone in a V1 position with any 12AX7 that I have with a 5751 in my amps.

I don't think a 12AT7 is as sweet musically as a 5751 or 12AY7 is, IMO.

I've never done it, but I wonder how close a paralleled 12AY7 would come to approximating a triode of a 5751?  I do think it would have a similar sweetness to it although the gain might be less.

Hoffman sells Sovtek 5751 tubes.

With respect, Tubenit

[kagliostro]

Few time ago, at a Ham Fest fleamarket, thinking to get 2 x  12av7 I got a pair of 12av6

is that comparable to 1/2 of 5751 ???

Kagliostro

[DummyLoad]

is that comparable to 1/2 of 5751 ???

not to be rude, but can't you look that up yourself? 

[tubeswell]

Few time ago, at a Ham Fest fleamarket, thinking to get 2 x  12av7 I got a pair of 12av6

is that comparable to 1/2 of 5751 ???

Kagliostro

12AV6 is a double-diode triode in one envelope designed for radio receivers. The diodes are for signal and AGC rectification.  The triode is an audio amplifier and is virtually identical to a 12AX7 triode.

[HotBluePlates]

Few time ago, at a Ham Fest fleamarket, thinking to get 2 x  12av7 I got a pair of 12av6

is that comparable to 1/2 of 5751 ???

Kagliostro

The 6AT6 is essentially 1/2 of a 5751. But you only get 1 triode, and you get 2 diodes you don't need. It also does not have a humbucking filament arrangement.

[firemedic]

kagliostro, I'm amazed you've been able to get by with just the tubes you find at hamfests, etc. Without new production tubes, anything I built bigger than my SE would be dead in the water.
The new tubes seem to work just fine, personally would prefer a Sovtek 5751 to any 12AX7.

[HotBluePlates]

You'd be surprised at how cheaply you can buy tubes at some hamfests. I can usually buy dozens of NOS (or lightly used 60's production) 12AX7's for the same or less than buying a new 12AX7. It all depends on the particular crowd you're dealing with.

[kagliostro]

Thanks to all for answers

DummyLoad

is that comparable to 1/2 of 5751 ???

not to be rude, but can't you look that up yourself?

Tubeswell

The triode is an audio amplifier and is virtually identical to a 12AX7 triode

I know that 12av6 is 1/2 12ax7, DummyLoad told it to me sometime ago ( http://www.el34world.com/Forum/index.php?topic=11590.0 )

Can I compare this 12AV6 to a tube of the 12**7 series ? which one ?
6AV6 w/ 12V filaments

1/2 12AX7 ignore the diodes.

--DL

Sorry I put the question the wrong way I was thinking to what Tubenit told

I don't think a 12AT7 is as sweet musically as a 5751 or 12AY7 is, IMO.

I've never done it, but I wonder how close a paralleled 12AY7 would come to approximating a triode of a 5751?  I do think it would have a similar sweetness to it although the gain might be less.

I should have said:
 
does the 12av6 has a tone similar to 5751
asking if someone knows the tone of that tube

However the reply to the question of DummyLoad

not to be rude, but can't you look that up yourself?

is that to me is difficult to understand datasheet

Firemedic

I'm amazed you've been able to get by with just the tubes you find at hamfests, etc.

From HotBluePlates

You'd be surprised at how cheaply you can buy tubes at some hamfests.

as an example (at Hamfest) I was looking for 5879 tubes  for some time without find anyone, then I find some NOS NIB JAN tubes for € 3.00 each, that I believe is a good price

thanks again

Kagliostro

[tubeswell]

Tubeswell

The triode is an audio amplifier and is virtually identical to a 12AX7 triode

I know that 12av6 is 1/2 12ax7, DummyLoad told it to me sometime ago ( http://www.el34world.com/Forum/index.php?topic=11590.0 )

Well according to this the only differences between the 12AV6 and the 6AV6 are the heater voltage and current ratings. The key characteristics I was looking at for a comparison to a 12AX7 were:

(assuming Va = 250)
Ip = 1.2mA (max)
mu = 100
rp = 62.5k
gm = 1600 umhos
Vg = -1 to -2V

Basically the same as a 12AX7

(Having said that, now and again some tube datasheets have been argued to be 'wrong')

[DummyLoad]

sorry kaglio - i assumed you knew how to compare average characteristics. please forgive if i came off as being rude.

while you're out there - be on the look-out for 6bv8 as well.

there are a several 1 triode tubes that are electrically similar to the 5751.

similar to 5751
6at6 - 7 pin
6aq6 - 7 pin
6bt6 - 7 pin
6bn8 - 7 pin - av is same but plate R is about 1/2.
6cn7 - 9 pin
6fm8 - 9 pin
6aq7 - octal pkg.
6k5 - octal pkg.
6q7 - octal pkg.
6sl7 - octal pkg. dual triode
6su7 - octal pkg. dual triode
6sz7 - octal pkg.
 
 

similar to to the 12ax7
6av6 - 7 pin
6bk6 - 7 pin
6dr4 - 7 pin
6f5 - octal pkg.
6sf5 - octal pkg.

similar to 12au7/6sn7
6bf6 - 7 pin
6c4 - 7 pin
6c5 - octal pkg.
6j5 - octal pkg.

[kagliostro]

Tubeswell

The key characteristics I was looking at for a comparison to a 12AX7 were:

(assuming Va = 250)
Ip = 1.2mA (max)
mu = 100
rp = 62.5k
gm = 1600 umhos
Vg = -1 to -2V

Thanks I'll try to remember that

DummyLoad

similar to 5751
6at6 - 7 pin
6aq6 - 7 pin
6bt6 - 7 pin
6bn8 - 7 pin - av is same but plate R is about 1/2.
6cn7 - 9 pin
6fm8 - 9 pin
6aq7 - octal pkg.
6k5 - octal pkg.
6q7 - octal pkg.
6sl7 - octal pkg. dual triode
6su7 - octal pkg. dual triode
6sz7 - octal pkg.

Thanks for the large list of similarity

MANY THANKS to you friends

Kagliostro