Is ok to replace 12ax7 for 12ax7 in my ampeg classic?

[Sinomis666]

I've got a few of 12ax7a's tubes floating around so I played around with them on my ampeg classic until I achieved a more beefier midrange tone but I'm unsure wether or not it will effect my amp particurly my power amp

[steamthief]

Perfectly fine, welcome to tube rolling!

[Sinomis666]

Yeah haven't done it in years &have got all sorts of preamp tubes lyin around not sure which tube had the most effect,though I think it might if been the Mesa tube in the driver section of the power amp that had the most effect in changing the sound...

[JimmyM]

So what have you got in it now?

[Sinomis666]

A Mesa 12ax7a 1st then a 90s groove tube 12ax7a in the preamp & another Mesa 12ax7 in the poweramp section, which seemed to make the most difference in tone!

[JimmyM]

The driver circuit is pretty important in those SVT's, so I hear. Glad it's working out for you, especially with using newer tubes. That'll save some cash over using NOS tubes, especially if you would have ended up liking Mullards

[grendle]

Originally Posted by JimmyM

The driver circuit is pretty important in those SVT's, so I hear. Glad it's working out for you, especially with using newer tubes. That'll save some cash over using NOS tubes, especially if you would have ended up liking Mullards

+1
Or EH, or Sylvania, or GE, or Telefunken......heaven forbid you start with 5751's ......lol. welcome to tube rolling

[Sinomis666]

Yeah which one do you recommend I'm in love with the bass sound on the first cheap trick album so I want lots of midrange!

[JimmyM]

Just turn up the midrange knob

[Sinomis666]

Ha I do but a like my settings pretty flat just a nudge tryin to get to sound as close to the 70s svts as possible! I will keep on playin around with the preamp tubes until I'm happy!

[Munjibunga]

You can pop ECC83s, 7025s and 5751s in there, too. I like the Eden-branded 7025 in my WT-300. I put NOS Selected Telefunken ECC83s in my Shuttle 9.0 and V1 of my DB750.

[Sinomis666]

Cheers guys I guess I'll just keep tryin out tubes when I find them I live in NZ so we don't have to much old gear here except ones you can hire

[96tbird]

The A after 12ax7 denotes the improved version. They changed the heater in them. The originals will flash like camera flash when you power up. The A variant eliminated this cool annoyance.
New production are likely all A style.I Just got my hands on a bunch of nos I gotta roll soon. Collecting tubes is addictive.

[Sinomis666]

Yeah also I read they are less noisy than the 12ax7

[JimmyM]

Originally Posted by Sinomis666

Ha I do but a like my settings pretty flat just a nudge tryin to get to sound as close to the 70s svts as possible! I will keep on playin around with the preamp tubes until I'm happy!

Well do whatever you need to do, but people in the 70's never set SVT's flat

[One Drop]

Originally Posted by JimmyM

Well do whatever you need to do, but people in the 70's never set SVT's flat

I use the Bass knob to EQ for the room if necessary, but the midrange knob with the 3 way switch is an extremely powerful way to sculpt your basic tone. Just a few clicks can take you from smooth and fat to full grind and a real hard-shouldered tone. There is no real practical reason not to use a bit of tone shaping with the way the mids are voiced- it's easy to still get your preferred tone room to room without hassle.

[Sinomis666]

I've got two guitarist's in my band & they do take up a fair bit of the midrange I do always try to find that sweet spot which also works in my favour or not depending on the room

[Sinomis666]

Ha your probaly right jimmy i also use pedals to also give me my tone normally depending on the room, gonna be blasting it out tomorrow at practice so that will give me a good idea about what works& what gets buried in the mix

[perogato02]

Originally Posted by 96tbird

The A after 12ax7 denotes the improved version. They changed the heater in them. The originals will flash like camera flash when you power up. The A variant eliminated this cool annoyance.

Whoa! Why would you want to get rid of that?
Athough I can imagine that it can make you jumpish after a while

[Bassmec]

Originally Posted by Sinomis666

Yeah which one do you recommend I'm in love with the bass sound on the first cheap trick album so I want lots of midrange!

Sadly you will want the most sought after ECC83/12ax7, the military spec ruggedized all copper pins and traces CV 4004 by Mullard.
Brimar ECC83 is strong in the mid too and the HI FI nutters
haven't discovered them to the same extent as Mullard.
GEC or Telefunken for sweet but bright.
In fact a few batches of RCA JAN 12ax7's where made by
mullards birmingham plant.
So If in the states then GE or RCA is always a good bet
for the money.
Companies mentioned that never made a tube in their lives include Mesa Boogie, Eden, Electro Harmonix and even Groove Tubes, don't actually make any tubes.
They all just grade other peoples product, mostly chinese
cheep tubes in better looking boxes.
Its the genuine NOS BVA marked tubes that make the big bucks these days.