Looking for 5751 or 12AY7 valves!

nicovlogg

Hey guys, I'm looking for a lower gain alternative to the 12AX7s in my Vox Night Train - in thick mode I run the thing at almost 0 on the gian dial.. So looking to tame that a bit. Not TOO keen on 12AT7s.. Let me know what you have please!

Attila

hiya Nic

I know these are not equivelents ........but I have loads of ecc82's and 81's if you want to experiment with lower gain tubes,

I think that its not so much the gain but rather the dynamic plate resistance (rp) interacting with circuit input and output loads that's most important.

nicovlogg

The 82 is the 12AU7 right? Doesn't that have insanely low gain?

How would the RP make a difference? I'm new to all this ?

MikeM

I'm also interested in what exactly you mean by that ?

Attila

Ahem !!!! let see if I can talk my way out of this one ???

My statement was "incorrect ish" or out of context .... what I should have stated was:

The 5751 is a 70 gain factor where as the 12AX7 is a 100 gain factor, with the same RP so it should be a direct drop in replacement with lower output

The 12AY7 on the other hand is a 45 gain factor but the RP is different, so the loading in the circuit will be different, it will work but there will be a circuit mismatch which will affect the tonality and amplification,

I may be splitting hairs ?

AlanRatcliffe

Attila wrote: I may be splitting hairs ?

Nope. Makes a difference. I find the 5751 keeps the feel intact, just dropping the gain. I find subbing in a AT7 or AY7 neuters the amp for my tastes.

There are also some great NOS 5751s to be had for relatively low prices compared to the good NOS AX7s.

nicovlogg

Yep I hear you.. So... anybody have a nice 5751 for me to try out? ?

Attila

Nic ...If I understand you correctly .... you want for more usable range on the gain controls with less fuzzy and more bluesy distortion and if you are using pedals....... you may want to try a 12AU7A (ECC82) to achieve that

I am serious on the offer if you wanan play around just come collect

AlanRatcliffe

Don't have any loaners, sorry. I got mine from Mr Valve a couple of years ago.

nicovlogg

Yep Attila, I'm looking for lowered gain and more headroom for pedals - this thing breaks up way too quickly to my taste. I'm keen to try before I buy so an AU7 might be nice, have you got a 5751 by any chance?

Attila

sorry buddy ... only as mentioned

Gearhead

I have one or two NOS 5751s you can borrow, your first post seems to suggest you were looking to buy :?

nicovlogg

Gearhead wrote: I have one or two NOS 5751s you can borrow, your first post seems to suggest you were looking to buy :?

I'd just like to try before I buy - I've been buying a few tubes and found that more often than not they just go in a shoe box - would like to make sure before I commit ?

Gearhead

Good stuff or not, just imagine that you can put your grandchildren through varsity with what that shoe box is going to fetch by then. NOS rocks ?