Different types of valves

[munkonthehill]

Hola all,

I am currently in the process of swapping out the stock preamp 12AX7 valves in my bass terror due to them not suiting my sound when I crank the amp.

Now I am looking into what I want to swap them with and I find various model types and vendors and to be honest I am now a bit lost. I know different types of valves with give me different sounds. But do the model types all have the same output or does it depend on the vendor that gives it a specific sound?

I like a trebly attack (think the striking F note at the start of Baba Oreilly). I know the EQ aint great on the OBT and I dont want to be restricted to playing low levels incase I get that horrible O/D sound sound.

So even if you could let me know what the differnt model number mean and then give me your thoughts on a prefered preamp valve.

I have read HappyJacks thread on the swap and he gave me some great advise tonight as well so all I need to do is find a valve.

Cheers
Steven

[Musky]

Preamp valve comparison thread: http://www.finnbass.com/showthread.php?t=22

[bigjohn]

Yeah, that finnbass page is a good place to start I reckon, if you're gonna go down the route of changing valves and paying any attention to what someone else thinks / hears in a different amp

I started there. Never bought any new valves. Just thought about it.

Came to the conclusion that what would be best would be to put the best, un-microphonic, most consistent valve in each socket in the amp. Treat that as ground zero. Then move on from there trying different valves in different positions. Valves, esp pre-amp valves are pretty hardy and don't wear out. Buying used is ok one tends not to lose too much money when experimenting in used electronics.

[clarkpegasus4001]

I would go for JJ Tesla if buying new. Secondhand? Mullard or RCA. You could try Hot Rox here in Nottingham he will give you all the advice you need and post you the valves.....
Website here: http://www.hotroxuk.com/ good luck.....

[Beer of the Bass]

I know some people change to a 12AT7 (or ECC81) to tame the overdrive a bit. Any 12AT7 will have less gain than the stock 12AX7 (ECC83). The two different names (12A*7 and ECC8*) are just the US and UK numbering systems for the same valves.
I don't have a Terror Bass, but I've swapped preamp valves around in a few different amps. The difference between brands of the same type are pretty subtle, so you're not going to radically change your sound with another brand of 12AX7.
Hot Rox have always been pretty good to deal with, and their prices tend to be OK, so I'd recommend buying from them.

Edited October 11, 2011 by Beer of the Bass

[thepurpleblob]

It's complete nonsense. It's just an electronic component - so if it works leave it alone. Changing it will only make a difference in your imagination. I'm sure I'm going to get shouted at but it's on the same level as gold-plated speakers cables and suchlike.

I assume you have the knowledge and equipment to set up the bias when you change the valve?

Never criticise a man's religion, wife, politics or valve-amp

Edited October 11, 2011 by thepurpleblob

[munkonthehill]

you dont have to rebias the valves in these amps. Surely with the valves and what they do as components in the preamp stage WILL have an impact in the overall sound of the OBT.

Plus there are a few folk out there who have made the swap and found the horrible O/D sound being calmed right down.

[geoffbyrne]

[quote name='thepurpleblob' timestamp='1318321700' post='1400366']
It's complete nonsense. It's just an electronic component - so if it works leave it alone. Changing it will only make a difference in your imagination. I'm sure I'm going to get shouted at but it's on the same level as gold-plated speakers cables and suchlike.

I assume you have the knowledge and equipment to set up the bias when you change the valve?

Never criticise a man's religion, wife, politics or valve-amp
[/quote]


I'm not shouting at you, but you are quite wrong about that. The different valves have quite different gains - AX being the greatest & AY/AU the least. This can make a huge difference to the performance of the pre amp.

My personal favourite is the 5751 which has 70%(ish) of the 12AX7 gain - not too low & enough still to get decent tone.

G.

[thepurpleblob]

I'm not sure I follow that argument. What has valve gain got to do with the tone? Gain just means louder or quieter which isn't very interesting. I can't help thinking that if simply swapping the valve to one of different manufacture makes an audible difference it really comes down to poor amplifier design - because it shouldn't.

If you used proper transistors then you wouldn't have all this bother

Mind you... as long as you are all happy

[thepurpleblob]

This is an interesting (and, I think, unbiased read) if you like this sort of thing... [url="http://sound.westhost.com/valves/myths.html"]http://sound.westhost.com/valves/myths.html[/url]

[Delberthot]

its more to do with the different properties of the valves so that you can turn your amp up louder without getting the overdrive or some prefer to have it at lower volume

ie we're not talking about a dozen different 12AX7 valves by different manufacturers which will still probably be slightly different, we're talking about substituting a 12AX7 for a 12AU7.

[kevin_lindsay]

[quote name='thepurpleblob' timestamp='1318321700' post='1400366']It's complete nonsense. It's just an electronic component - so if it works leave it alone. Changing it will only make a difference in your imagination. I'm sure I'm going to get shouted at but it's on the same level as gold-plated speakers cables and suchlike.

I assume you have the knowledge and equipment to set up the bias when you change the valve?

Never criticise a man's religion, wife, politics or valve-amp [/quote]

You're talking nonsense mate. And I suppose different string types make no difference either ? Flatwounds and roundwounds sound the same too as they produce the same notes, huh?

Different valves from differing manufacturers sound different as they can found bassier or treblier, or can sound cleaner or more distorted depending upon the way they are constructed.

[thepurpleblob]

[quote name='kevin_lindsay' timestamp='1318354889' post='1401095']
You're talking nonsense mate. And I suppose different string types make no difference either ? Flatwounds and roundwounds sound the same too as they produce the same notes, huh?

Different valves from differing manufacturers sound different as they can found bassier or treblier, or can sound cleaner or more distorted depending upon the way they are constructed.
[/quote]

Well, ok, you'll excuse me for ignoring your string remarks because I simply can't see any parallels at all. Not unless your strings have negative feedback, of course

Yes - I am well aware of the mythology surrounding valve replacement and the bizarre effects that are attributed to a simple (and pretty much technically obsolete) amplifier component (e.g. the ability to add bass or treble). However, I don't want to get into some flame argument at all. So, I'll just leave it like this. I spent a lot of years servicing amplifiers - mostly transistor based, admittedly, but I'm far from unfamiliar with valve equipment. All I can say is that - when correctly set up and all else being equal - I have never been able to detect the slightest difference. If you can and that gives you a result that you are happy with then that's great.

Edited October 11, 2011 by thepurpleblob

[Slipperydick]

[quote name='thepurpleblob' timestamp='1318356341' post='1401113']

Well, ok, you'll excuse me for ignoring your string remarks because I simply can't see any parallels at all. Not unless your strings have negative feedback, of course

Yes - I am well aware of the mythology surrounding valve replacement and the bizarre effects that are attributed to a simple (and pretty much technically obsolete) amplifier component (e.g. the ability to add bass or treble). However, I don't want to get into some flame argument at all. So, I'll just leave it like this. I spent a lot of years servicing amplifiers - mostly transistor based, admittedly, but I'm far from unfamiliar with valve equipment. All I can say is that - when correctly set up and all else being equal - I have never been able to detect the slightest difference. If you can and that gives you a result that you are happy with then that's great.
[/quote]

I think your right, I spent years working with Valve kit, A lot of, but not just amps, and to be honest the difference between makes was rarely noticeable even back the, when there were loads of different manufactures, or at least distributors. Many valves were imported and then printed with whatever logo that was ordered by the distributor. These days there are far less factories around the world actually manufacturibg them, But they will be graded (or at least thats what we are told by the people who sell the expensive ones)
So how different are they likely to be ?

If you want less gain without altering the circuitry, try using ECC81/12AT7 or 82/12AU7, or there are always industrial equivalents around. Have a look at the british valve museums site.

Only my opinion based on experience mind.

[charic]

Not going to get too involved as I know right next to sod all but I think the statement at the moment is:
Manufacturers sound similar if not the same
Different ratings or numbers or whatever they're called can sound different.
I'm back off to my corner

[skankdelvar]

[quote name='charic' timestamp='1318359339' post='1401168']
Manufacturers sound similar if not the same
Different ratings or numbers or whatever they're called can sound different.[/quote]
Pretty much my opinion, tbh.Tweaking the EQ has a more audible effect than swapping in different types of 12ax7, IMO.

I once did a very sad '12AX7 evening' when a mate and I spent hours swapping a bog EHX, a bog Groove Tubes, a JJ, a Brimar, a 60's RCA and an old Sylvania in and out of a blackface Bassman, an Epi Valve jr, a '73 non-MV Mk2 Marshall, a Rivera R55 and a silverface Princeton. And stroking our chins a lot.

It would be nice to be able to reproduce our findings but we had a bottle of Jameson along for the ride and neither of us can remember which sounded best in what.

Edited October 11, 2011 by skankdelvar

[charic]

[quote name='skankdelvar' timestamp='1318361377' post='1401217']
It would be nice to be able to reproduce our findings but we had a bottle of Jameson along for the ride and neither of us can remember which sounded best in what.
[/quote]

I think this can account for many a lost musicians thought tbh

[Pentode]

And was the Jameson NOS and did it taste any better?

[skankdelvar]

[quote name='Pentode' timestamp='1318364226' post='1401267']
And was the Jameson NOS and did it taste any better?
[/quote]
I once did a very sad Irish Whiskey evening when a mate and I spent hours etc,etc. And stroking our chins a lot.

It would be nice to be able to reproduce our findings but we had a 12AX7 along for the ride and neither of us can remember which tasted best.

[munkonthehill]

Ok so far I have found that different vendors produce very different sounds in the valves and its the actual valve type IE..12AT7, 12AX7, 12AU7 that actually give the different types of gain thats produced. So thats that sorted

Now its just finding a valve that will allow me to have nice trebly attack without distorting so much you are unaware of which note your playing!!!!

[lollington]

I've just bought a Sovtek 12AX7WB because it's pretty cheap and gets fairly decent reviews. Placing this in my EBS valvedrive pedal in the hope that I can tweak a little more grit out of it.

It will be my first time experimenting with vales. If it works then bangarang, more noise. If it doesn't, then at least I have a spare valve. It's also tempting to try something like this in the LH500, but without a gain control this would be less fun, and I'm not sure I would hear the difference...