Valves for Bass amp

[badboy1984]

I'm all new to Valve. Currently using a LB30 and had the amp for some time now and I fancy to change the valve for a set of new ones. At the moment the valves is the stock valves that comes with the bass and my LB30 is the made in china version.

On the Ashdown spec sheet it says:


Pre-Amp Tubes 1x ECC83 and 1x ECC82

Output Tubes 4x EL84



Their are so many valves in the market but I'm not too sure which one shall I look for.

[Roland Rock]

A good place to start would be phoning either Hotrox or Watford Valves. Both are very knowledgable and helpful, and should be able to guide you towards what you're after.

http://www.hotroxuk.com/matched-valves-links-page-12ax7-6l6-909-0.html
http://www.watfordvalves.com

[Happy Jack]

I've been faffing about with different types of valve amp for a few years, no sort of expert but a reasonably experienced faffer.

You'll need very good ears indeed to hear much change between various types of output valve. Once you get above the lowest-quality units, a valve is a valve, IMHO.

Input valves are different. Like wines, they attract all sorts of fanciful adjectives (smooth, creamy, crunchy, sparkling) which actually tell you very little until you've heard that particular valve used in your amp, with your bass played through it, by you.

There's a shedload of information about pre-amp valves on the Net but be warned, most of it is aimed fair & square at guitarists rather than at bass players.

The ECC83 is the most widely-used pre-amp valve, and it's also commonly known as the AX7.

If that's too high-gain (i.e. breaks up easily into distortion) for your tastes, try the next step down which is the AT7. That's a roughly 40% drop in gain level leading to a much later break-up.

Watford Valves have attracted mixed reviews on Basschat. I really like them and have had nothing but good service from them, but I am aware that others have had different experiences.

[badboy1984]

Thanks for the information, I will look it up and try understand the theory behind it. Is like a whole new thing i need to understand.

[franzbassist]

[quote name='Happy Jack' timestamp='1394100875' post='2387859']
If that's too high-gain (i.e. breaks up easily into distortion) for your tastes, try the next step down which is the AT7. That's a roughly 40% drop in gain level leading to a much later break-up.
[/quote]

This is good advice, and there's great info [url="http://www.thetubestore.com/Resources/Guitar-Amp-Info/Gain-Factor"]here[/url] which will give you more info on this subject. I swapped out my 12AX7/ECC83 preamp valves for 12AT7/ECC81s when I owned an LB30 and it cleaned it up wonderfully. I could also hear differences between makes, but only when listening back to a/b recordings I made: live they made little if any difference in a band context.

[badboy1984]

So does the preamp valves effect the break out level? or is the power valves that effect this? I would like the amp to break up much later then early. 40% drop in gain on the AT7 means volume level decrease as well?

[brensabre79]

Both input and output valves will break up. But you have to drive the output valves pretty hard to get them to do that. Having 40% less gain on the pre-amp will mean you have less gain to make the power amp valve break up - it's all related.

The short answer about the volume drop is yes, the lower gain valves will not be so loud. If the amp is too hot (i.e. you have the pre-amp section turned right down to avoid distortion), then you'll benefit from the AT7 replacement. If you can control it fine with the AX7s then I wouldn't bother.

There is a sweet spot in my opinion just before the break-up stage. This is where you'll get a bit of compression from the valves, go one louder and you'll hear distortion. if you can get the controls balanced well, you can get this sweet spot from both the preamp and power amp. But then you're pretty much stuck at that volume which isn't always practical.

It's one reason why with valve amps you don't need so many watts, and that even if you did, you would not be getting the best results from it. Sure you can build a 1000W valve amp (if you have a roadie), but to get that sweet spot it would be so incredibly loud that it just wouldn't be useable.

[badboy1984]

The reason why I ask this is because I'm doing a gig on Saturday and I know the LB30 with my BC212 can handle the venue because is a small venue in a social club place. I don't usually gig on my LB30 because in most places I either DI straight to the desk or use someone else amp on stage.

I've got a feeling my LB30 will sound lovely for the gig but for some reason I don't trust those valves until i replace all of them with the new ones. This is because the valves come stock with the amp and not sure how it was treated in the shop before I bought it.

Edited March 6, 2014 by badboy1984

[badboy1984]

Any particular reasons why the preamp tube use one 12ax7 and 12au7? One is high gain and one is pretty low gain.

[DiMarco]

If you are not looking for breakup but merely some tube warmth, I have heard that utilizing JJ ECC83S valves is great for a bass amp.
Can someone confirm this? I want to get some spares for my Trace Elliot SMX amps just in case. With the SMX you can blend the solid state and valve signals.

[Dad3353]

[quote name='badboy1984' timestamp='1394110625' post='2388004']
The reason why I ask this is because I'm doing a gig on Saturday and I know the LB30 with my BC212 can handle the venue because is a small venue in a social club place. I don't usually gig on my LB30 because in most places I either DI straight to the desk or use someone else amp on stage.

I've got a feeling my LB30 will sound lovely for the gig but for some reason I don't trust those valves until i replace all of them with the new ones. This is because the valves come stock with the amp and not sure how it was treated in the shop before I bought it.
[/quote]

Valves don't get 'abused' in shops. They last years, usually. New ones will be no more (nor less...) reliable than those already in there. Buy a set as 'spare', if you like, but they'll still be in your gig bag in a decade, probably, unless you're just unlucky. If it's simply a question of 'trust', I shouldn't touch 'em.
I've been playing through valve gear for several decades, as has our son, and several buddies (Fender, Hiwatt, Mesa, Marshall and more...). We once had to change a pre valve in a Mesa Simul 2-90, and once in a Laney VC-50. That's all. I've never had to change power valves (although I've done it, it wasn't because they were 'stuffed', it was because I needed a different sound...).
Just my tuppence-worth; may not apply to your specific amp.

[quote name='badboy1984' timestamp='1394110933' post='2388008']
Any particular reasons why the preamp tube use one 12ax7 and 12au7? One is high gain and one is pretty low gain.
[/quote]

A brief read-up on how these things work could be useful. It seems to me (I could be wrong...) that you're over-thinking this. The basics are simple, they're just amplifiers. Here's a Wiki view...

[url="http://en.wikipedia.org/wiki/Valve_amplifier"]Valve Amps...[/url]

...and a more detailed one...

[url="http://www.premierguitar.com/articles/17116-how-tube-amps-work"]How they work...[/url]

There are many subtleties, as in all subjects, but it's not much help (imho...) just considering the gain of valve X against valve Y without the rest of the picture.
Hope this helps; no malice intended; good luck for the gig.

[badboy1984]

I think you are right, I am start to over think the whole concept of valves. The more information I see the more I start thinking about changing etc. The amp probably work fine to behonest and will last a decade like you mention.

Is good that I know more now and hopefully I can sleep through this tonight and wake up tomorrow and not planning to change any valves etc.

[VTypeV4]

I wonder if the 12AU7 is used in the driver stage? These are lower gain as stated but can deal with a greater current and as such are often used as the driver valve..

[Subthumper]

Hi, welcome to the world of valves. The main cause of valve failure is moving them about and thrashing them before they warm up properly. Obviously you have to move it but try and avoid knocks and drops and Make sure it's got decent rubber feet to isolate it from vibration when the car and from the speaker cab. Always let the amp warm up for at least three minutes, five or more is better as it gets the temperature evenly distributed throughout the valves glass envelope. It also allows the bias voltages to fully stabilize. I've worked on lots of different amps and built three, and all of them take at least three minutes to stabilize. Operating the amp before this has happened results in the power valves running too hot u.til the bias voltage comes up.
The other thing to do is to let the amp cool down before you move it. And don't forget to make sure the impedance is correctly matched to the speaker.
I use a valve amp all the time but I don't carry spare valves, it's easier, quicker and less stressful to have a spare head, in my case a Hartke 3500. I've only needed it once in the last four years.
Follow this and you should have many years of valve fun.
Cheers Just

Edited March 6, 2014 by Subthumper

[Handwired]

[size=4]The Tung-Sol 12AX7/ECC803 is my fave for V1 position at the moment, however if you're thinking about lowering the gain a bit, then look at a good quality ECC83/5751 instead, it tightens up the low end as well.[/size]

[Scott_LP]

I know that some amps require the valves biasing once installed, mine included. I don't know if that would be the case here.

I only mention it as a friend of mine's amp failed after just 6 months as the new valves weren't biased by the amp tech, who believed it not necessary due to him installing matched pairs.

Just a thought. :-)

[badboy1984]

I did contact Roland in Salford about checking the amp out, the gig is on Saturday and I can't do it till next week so I'm taking a gamble to on Saturday and hope it won't fail on me.

The amp was purchase new and I don't use it at home so it should be ok.

[VTypeV4]

[quote name='Scott_LP' timestamp='1394203927' post='2389142']
I know that some amps require the valves biasing once installed, mine included. I don't know if that would be the case here.

I only mention it as a friend of mine's amp failed after just 6 months as the new valves weren't biased by the amp tech, who believed it not necessary due to him installing matched pairs.

Just a thought. :-)
[/quote]

Not sure that applies to the little Ashdown as I [i]think[/i] it's cathode biased..

[Dad3353]

[quote name='badboy1984' timestamp='1394206273' post='2389171']
I did contact Roland in Salford about checking the amp out, the gig is on Saturday and I can't do it till next week so I'm taking a gamble to on Saturday and hope it won't fail on me.

The amp was purchase new and I don't use it at home so it should be ok.
[/quote]

This may be an interesting read for some...

[url="http://btpub.boyd-printing.com/article/Ashdown+Little+Bastard+Bass+Head+and+VS-112+Bass+Cab/1236664/135014/article.html"]LB30...[/url]

[mickster]

[quote name='VTypeV4' timestamp='1394207328' post='2389186']
Not sure that applies to the little Ashdown as I [i]think[/i] it's cathode biased..
[/quote]

Spot on, this amp is cathode-biased so no need to take it for rebiasing after a power tube swap. And you're also right about the 12AU7 valve in the LB30; it's a phase-inverter / driver so should prbly be left as is. If you want to experiment with changing the tone, i'd start by changing the 2 ECC83s (on the left side of the amp as you look at it from the front) & the power tubes.

[skankdelvar]

[quote name='badboy1984' timestamp='1394206273' post='2389171']
I did contact Roland in Salford about checking the amp out, the gig is on Saturday and I can't do it till next week so I'm taking a gamble to on Saturday and hope it won't fail on me.
[/quote]

Don't worry. You really should have no cause for concern unless the amp is making funny noises or you've hammered it at full beans every night for the last six months.

We aren't talking about fine china here. A well-designed and constructed valve amp should last for years and so will the tubes if used sensibly. I just sold a 1977 Marshall head which IIRC was last re-tubed in 1990. Switched it on the other week after 10 years in storage and it worked fine.

As has been pointed out apparently your LB30 doesn't need re-biasing, which in turn relieves you of the need to worry about 'matched pairs' of output valves (which some believe to be a bunch of snake-oil anyway). Forget about the power tubes unless you've got an audible problem.

Short of some serious work which will be entirely beyond you, what it comes down to is whether you stick a new pre-amp valve in the front end and - if so - whether it's a different 12AX7 or a 12AT7. You [i]will[/i] notice a bit of a difference but not compared to turning the amp's gain up or down.

[badboy1984]

Done the gig last night on the LB30 with the TC BC212 cab. Mix feeling about the tone and volume. First I had the volume about 12.00 - 1.00 o'clock position and the volume is plenty enough but the tone is warmth but dirty. I would prefer a much cleaner tone.

If I swap the valves to less gain that means I will get much cleaner tone but volume drops. Looks like I need to add more cab to make this work.

I feeling like my tone is lemmy style which works on some song but not all. When playing some quiet songs with light touch the amp sound fantastic and clean. Only get dirty when I start picking the strings heavily.

[skychaserhigh]

You need a bigger amp. The LB30 isn't really meant for loud gigs to be honest.

[The fasting showman]

I think as above, and also the comments from Skankdelvar, I wouldn't get drawn into swapping preamp valves in a quest for more headroom as some valve emporiums might have you do. You will hear detail differences at home but all will be lost in a band context I feel.
I had good use out of 100watt valve heads with an efficient bass (Stingray etc) and an efficient cab (big bass dedicated 4x12) either side of them playing rock at pub gigs, various amps over a 20 year period. I'm not using valve amps nowadays though.
I have owned a few Fender Bassman 10 combos(the '70s 50 watt valve 4x10 ones) over the years and I could nearly use them for louder stuff but not quite, the trying to get a quart out of a pint pot thing constantly! I'd imagine that the LB30 is similar, great for very civilised gigs, folk stuff and for playing with musicians that (another horrible phrase!) 'can see the big picture' unlike the situations I've been in. The Bassman 10 was always limited by the small output transformer ultimately, no amount of valve or speaker swapping really helped much. Good for recording though.
All the best, I'd try and use the LB30 where it will excel and enjoy it for what it is.

Edited March 9, 2014 by The fasting showman

[badboy1984]

I'm start thinking about buying a micro head. Not sure do i want to buy 500watt into 8ohm cab or 250watt in to 8ohm cab.