Are some amps designed for rubbish valves

[hamfist]

So what would be a better NOS valve and what would be a better new valve or are these fine?

what about JAN 5751, how would that sound, iv'e heard they are interchangable with 12ax7's ?

Very difficult questions to answer.

It all comes down to personal preference but I find that good (ie. testing near new) Mullard/RFT/Brimar/Mazda 12AX7's to be so much tonally richer (in the guitar-friendly frequencies) than the modern equivalents.

A JAN 5751 is a NOS (vintage) tube - "JAN" designates that it was manufactured for the miltary (some damn fine guitar players in the military of course !). A 5751 is a lower gain version of a 12AX7. Might work well in your amp. Certainly works well in some, and not so well in others - it all depends on what you are looking for. NOS 5751's also tend to be significantly cheaper than NOS 12AX7's so are good value in that sense.

If you have a high gain amp, where you don't use anywhere near all the gain, and also want to tighten the general feel of the amp up a bit, a NOS 5751 in V1 often works a treat !

[martinw]

I'd take a good old valve any day of the week, both for tone and reliability.

You can take some of mine. I'll swap you for some new JJs.

The thing is Martin, that I'm convinced that you must have some old, knackered vintage valves. I can think of no other explanation as to how you seem to prefer new valves.

Here's one that might rock your world: I have different taste to you, Maybe you don't have the definitive opinion?   

The valves are NOT knackered, as I have said before. I've tested them.

[martinw]

an amp could have been designed to work with a higher tolerance value of a valve, so it sounds good with a wider range of valves, thus eliminating some of the shortcomings of a cheap valve.

With respect, I don't think that's the case, and in fact I wouldn't know how to do it.

[hamfist]

Maybe you don't have the definitive opinion?   

Don't you dare give my wife any such ideas !

that WOULD rock my world !

[martinw]

Maybe you don't have the definitive opinion?   

Don't you dare give my wife any such ideas !
that WOULD rock my world !

:lol:

[HTH AMPS]

I got all my NOS valves before the prices went crazy - got a box full of Mullard/Brimar/Mazda etc... plus some US preamp valves, mostly ECC83/12AX7s but also some ECC81s, ECC82s and a probably around twenty EF86s.  then there's the output valves, but thats a smaller collection.

At the minute I'm trying out various oddball valve types that aren't common in amps but are so far turning out to sound great - got an amp wired up for an EF184 which cost £2.00 and sounds every bit as good as an EF86.  pinout on the base is different though, so it's a socket rewire job and the preamp will need re-jigged too.  however, if you've got the knowhow to do it, you're quids in.

Also got a box of 100 7-pin preamp valves that I'm hopeful will yeild good results - only paid £13.00 for the lot, so it's not exactly a big risk.  Got some of the 7-pin preamp valves (6AT6's) in that joblot that Fender used in early tweed amps such as the 5F10 Harvard.  Just goes to show, if you look around you can have NOS quality without the price.

[theroyalconsort]

I'm familiar with this story.

I blame Soldano and Mesa.

Mesa use cheap tubes and match them to thier kit. As a result when you buy a Mesa tube its supposed to be plug and play and problem free.

Soldano recomend and use Sovtek tubes as they are fairly consistant and it allows them to send amps out stock that sound consistant.

Then after the story goes through 1,000 hands we wind up with the idea that they are designed with cheap tubes in mind.

Tubes do change the tone of an amp but quite frankly tone stacks in tube amps arnt so complex that they can 'fix' the tone of cheap tubes.

Especially as one of the problems with them is inconsistency.

[Dmoney]

might be worth mentioning that Soldano bias their output tubes for the cleanest output they can get and do so by using tone generators and oscilloscopes when measuring the bias of an amp. therefore they don't have a strict recommended bias for their amps.

i think thats a different approach to measuring tubes, and building on mass to a certain spec, and never really checking, but just putting in a certain grade of power tubes and going for a generic bias.

which is a cold fixed bias amps usually style. helps the user who doesnt know how to bias but can pull out tubes and put new ones in without needing to really check.


anyway. im not making the point on biasing. im trying to say Soldano go into depth when biasing amps with sovtek 5881's and similar. i thought that might be an interesting point to make.