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#4
Yes, I'd say that's a good idea. If you have a schematic of the amp we can show you which cap to remove.
#13
The bright caps are c22 and c23. They are activated by pulling the master volume knobs out. If you leave the knobs pushed in the caps are removed from the circuit so physically removing them from the board would have no further effect than simply leaving the knob pushed in.
Try different tubes instead. What are you running at the moment?
JJ ECC83S valves will work very well. I'd grab a JJ ECC803 or two as well and just experiment with them in different positions.
If you want to dig around Ebay, look for German RFT 12AX7's. Those are the dark tubes of the NOS world.
If JJ or RFT tubes don't sort it out, then start looking at modding the TMB - but not until you try different tubes first. The last thing you want to do is hack the amp only to have to do it again next time you change tubes.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#14
Thanks for replying man. I put 4 new JJ ECC83s in and nothing really.

I'm getting nice warm bassy tones from the low sensitivity input, but now I can't get the distortion from the AOR channel I like :|

I'll look at those tubes, thanks.

Do you know if a soundcity 100w mark 3 will be any nicer?

Thanks for all the help

Luke
#15
You should be able to get a nice sound out of an AOR. How old are your power tubes?
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#16
No idea how old they are. They look like cheap shit though.

I have some new JJs ready to put in and bias them...Am I able to put them in and not bias them to see if the tone improves before forking out money to service it?

But if they're biased too cold anything will sound like shit?
#17
You should be able to. Just watch them closely, if they start to look red turn it off. Biased too cold will make it sound a bit flat but shouldn't sound like crap really. You should learn how to rebias it yourself, you're going to have to do it again in two or three years anyway. Not knowing how to bias your amp is a bit like not knowing how to change the tyres on your car.
If I were you I'd just bite the bullet and stick them in and get it rebiased. Get your tubes sorted out first before doing anything radical. Don't even attempt to mod the amp before you do that. That would be a fool's game.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#19
Ah, the dreaded AOR socket problem. That's the weak point in an AOR. If I owned an AOR the first thing I would do is replace all the tube sockets. Do that and they are as reliable as any amp out there.
Or are you saying that the socket itself is loose relative to the chassis? If so that shouldn't matter but iirc they are held in with bolts, not rivets, so you should be able to just nip them up. If it's tube relative to socket then it's done the old AOR socket failure thing.

I've seen people finding bias probes for about $30. They are just simple ones that you use a multimeter with. Myself, I just build my own. I have a blog in my profile that explains how to make one.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#21
Sorry I'm on my shiteberry and didn't see your last post.

Hmm I have no idea. I can wiggle the powertubes with ease though. The pre amp sockets are tight though.
Is it an expensive job?

Ah awesome I shall check that out. I'll probably just get this biased by a pro this time as I'm taking it in to get issues sorted.

If tomorrow it sounds as nice as I think it does...speakers or a new fuzz pedal will be ordered to celebrate!

Its been too long an issue with my aor's. I've had 2...no idea why as my last one had issues too!

Cheers mate
#22
Replacing sockets shouldn't be too expensive. It is a fiddly job though. How much it costs depends on how long it takes; how long it takes depends on the competency of the tech. If you can solder ok you could change them yourself. Take pictures of the socket before you desolder the wires and just put it all back exactly as it was.
Like I said, it can be fiddly so don't do it if you aren't competent working in tight spaces. And as always - discharge the filter caps before you touch anything inside the amp. The only discharge path in an AOR for the caps is via the tubes so they won't drain it past about 100V.
It is always wise to spray a bit of contact cleaner on the tubes pins before replacing them (Deoxit is good). The sockets being dodgey can result in a bit of filth in the socket so cleaning them is quite important. Be very careful replacing tubes in that thing with the original sockets, they'll break if you look at them too hard.

Edit. Actually, most of the sockets in that are PCB mounted aren't they? Those require you lifting the board out and putting new ones on the board. That shouldn't be too hard at all, you just need sockets with the right pins. Just be careful not to pour too much heat into the board when desoldering. Get your iron to just the right temp before you do it.
If you can't find the right ones here you won't find them at all:
http://www.partsconnexion.com/index.html
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
Last edited by Cathbard at Oct 13, 2011,
#24
thanks for that advice mate. I might try to replace those myself...cheers for that link too. I'm thinking of getting bias tool too but I don't want to pay the £120 for the bias master one. Do you know where I can get a decent-ish one for cheap in the UK?

Couldn't I get a cheap ohm/ voltage metre instead and get the tube socket things?

Sorry if these are silly questions!

And yeah I know why you'd say about single coils, but I do prefer the tone opposed to humbuckers!

Thanks, Luke.
#25
Bitch check yo' PMs.

1977 Burny FLG70
2004 EBMM JP6
2016 SE Holcolmb
#27
#30
Any of those should work fine.
You don't need much in the way of a meter, it just needs a 500 or 600V dc range and something that reads down to few millivolts dc. Say a 200 or 500 mV range. It doesn't even have to be particularly accurate. I can't see what ranges are on the blue one, the yellow one has the required range and it's only 10 quid so I'd probably grab that one.
The cheaper probe looks a bit suss to me. It says you still need to mod the amp to insert a 1 ohm resistor yourself. That's bollocks. You want one that you just plug in and go so get the 35 quid one.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#32
It's just a little trimpot. Been too long since I've poked my head inside one of those to remember where it is physically. Its a just a small 22K trimmer you adjust with a screwdriver. It is somewhere between the power supply and the output valves. I'm pretty sure it's the only trimpot in there.
It will look something like one of these:
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#33
I just took the amp out and can only find something with a screw located there you said but can't see any sign of a trim pot. There are wires going off from it though so it must be?

God I sound silly haha
#34
Pictures? It will be on the circuit board somewhere.

It's on the board towards the rectifier diodes near the two electrolytic capacitors. It looks like the one in the top left of the picture I posted.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
Last edited by Cathbard at Oct 16, 2011,
#35
Ahhhhh I found it mate. Looks like a cheap trim pot. It says "BIAS ADJ" under it so I assume its right haha :laugh:

I tried uploading a pic from me phone here but hasn't worked...I don't think?

I'll do one tomorrow just to make sure.

I was looking off the PCB board lol

Cheers mate again
#36
Yep, you've found it.
Good luck. Once you sort out how to do all this it will save you quite a bit of money. You'll be able to swap around power tubes any time you like. It's a skill everybody that owns a tube amp should have. Not knowing is like not knowing how to change the oil on your car. You can get away with not knowing but if you don't learn how you're being a dumbass.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#37
Haha excellent way of putting it. I was going to do this like 2 years ago but have just been lazy. Getting my amp biased here where I live will cost around 35pounds. Sooo...for 20 more, I can do it as many times as I like rip off really.

Any decent links to show how to drain the amp of any voltage (?) Still there? I'm thinking of replacing the tube sockets. Do I need to do this when biasing too?

Cheers!
#38
Quote by moominman2
I have a Laney AOR50w Head series 2.

I find its too bright/ harsh with my stratocaster so will removing a bright cap help ?

Thanks, Luke.


yes, also. changing pots could help (buy yer prob already running 250K). could also try rolling back on your volume knob a bit or adjusting the tone knob on the guitar.
punk isn't dead, it's always smelled that way.

"A perfection of means, and confusion of aims, seems to be our main problem."
-ae
#39
When doing the biasing on an amp you have to work on a live circuit so discharging the caps is a moot point. When poking around inside a live chassis only ever put one hand in there - keep the other one in your pocket. And be careful what you touch, the pinky finger is always the one that gets zapped - and it bloody hurts. So be aware of what you are doing with your pinky, it has a habit of sticking out. Oh - and ALWAYS wear shoes. The last thing you want is a current to pass from your hand across your chest and down a leg to ground. It's current across the chest that kills people. Don't wear shorts either. I've had a current go from hand to knee once because I was leaning against a chassis wearing shorts and it hurt like hell.
If replacing the sockets then yeah, you have to discharge them. Ideally you'd use a 1K resistor soldered onto a piece of wire and hold it across the capacitor terminals for a couple of seconds. Most of we techs don't bother and just use a piece of wire. I actually just use an old multimeter probe that with an alligator clip on one end. I clip the alligator clip onto the chassis and then touch all the positive terminals of the caps with the probe end. You get sparks but it's somehow satisfying to see a spark, that way you know you've done the job.
If you are smart you'll make a timber frame to sit the chassis into to work on.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#40
Cheers gum.

That seems a lot to take in and is kinda off putting haha. I'll definitely be biasing my own amps now, but I might take it to a tech for the sockets. I don't feel confident enough and also with soldering so I'll leave that bit. Thanks for all the tips given. I didn't realise you have to work on a live circuit but that's cool.

Will the tube sockets have any affect on amps performance in anyway?
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