Valves??

JimiTime

Hello y'all,

I've got to replace the valves in my Marshall TSL 601. 4 ecc83's and 2 el34's. however, their are various makes at various prices for these. just wondering, is there differences between the valves? Noise, tonal etc? I play a fender strat with texas specials through it. Love it clean and punchy. Any advice?
Thanks.

JimiTime

Is this in the wrong forum? Is there another forum for this kind of techie stuff? Or is there just no-one who knows anything about valves around?

Cheers.
Jimi

feylya

Give it time. People were more than likely away over the long weekend. Wait til Eoin Madsen appears. Then you will have too much information about tubes

I don't know enough about tubes to offer up an opinion unfortunately.

JimiTime

feylya wrote: »

Give it time. People were more than likely away over the long weekend. Wait til Eoin Madsen appears. Then you will have too much information about tubes

I don't know enough about tubes to offer up an opinion unfortunately.

Gr8. I was just making sure there wasn't another forum for amps and stuff. Hopefully will get some good info soon:) Cheers.

-=al=-

ive to change the ones in my tsl100, no idea what im doing though when it comes to this kinda thing, I think it has el34's

Eoin Madsen

JimiTime wrote: »

Hello y'all,

I've got to replace the valves in my Marshall TSL 601. 4 ecc83's and 2 el34's. however, their are various makes at various prices for these. just wondering, is there differences between the valves? Noise, tonal etc?

Yes, and yes. You shouldn't have too much issue with noise in new valves, but the tonal properties vary considerably. I haven't tried every valve, but I would suggest avoiding anything cheap or unbranded.

I play a fender strat with texas specials through it. Love it clean and punchy. Any advice?
Thanks.

JJ/Teslas are a safe bet, and a definitely step up from whatever valves came stock with the amp. They seem to be preferred by most vs Sovteks or Electro-harmonix, especially in Marshall amps.

I get valves from http://www.watfordvalves.com, they have great quality control. Bear in mind that if you change the EL34s the amp is going to need a bias adjustment.

Voodu Child

I second JJ/Tesla's, though i confess to not being a Marshall man.

One small problem is that while there are generally agreed 'top-notch' brands of valves, youll find what sounds brilliant in one amp might not sound so good in another.

So joining a Marshall forum and asking guys what they recommend for a TSL might give the most relevant answer. You'll find a lot of guys who have tried a lot of valves just in your specific amp, so they might be able to steer you in a direction that suits exactly what you're looking for from your amp.

JimiTime

Thanks guys, much appreciated. One thing that was touched upon was the biasing. Is there a DIY guide to it, or do you need a techie to do it? My bros an electroics whizz, does not deal with amps and stuff, but do you reckon he'd know what to do, if DIY is unwise?

Thaks again guys,
J.

Voodu Child

There are lots of amp biasing guides on the net. If you have trouble finding some, report back and im sure guys here will help you. There might even be some stuff in the resources.

Working on a valve amp is extremely dangerous if you don't know what you're doing. If you DO know what you're doing, its pretty simple and quick. If you say your brother is an electronics whizz, i'd hazard a guess that he'll be well versed in the dangers and safety precautions, and should be able to understand any technical instructions and safety advice. Definitely make sure he reads up plenty before doing it, and take it to a pro if either of you feel uncomfortable with it.

Here's the official Marshall service bulletin for the TSL series. It's not a bias-ing guide as such, it'll only make sense if you already know what to do, but the specific bias mV settings for the TSL series are necessary to know:

MARSHALL SERVICE BULLETIN

SUBJECT: Bias Info/Procedure for JCM2000 series Marshall amplifiers

THEORY OF OPERATION: We are setting the bias using the current method instead of cross over distortion method. The Bias PCB assembly is as follows:
PR1: Bias mini-pot adjustment for pin1 which is one side of the push pull amp (two output tubes in a 100watt amp and one output tube in a
50watt amp). Pin1: Connected to the cathode of the output tube(s) which then goes through a 1 ohm resistor then to ground. Pin2: ground reference.
Pin3: Same as pin1 but for the other side of the push/pull amp. PR2: Bias mini-pot adjustment for pin3, the other side of the push/pull amp.


PROCEDURE:
1. Make sure amplifier is connected to a load with the proper impedance
selected. 2. Power up amplifier on STANDBY and let the circuit stabilize for a couple of minutes.
3. Locate the male three pin molex connector (CON2) with the two mini-pots (PR1 and PR2) on both ends found on the bottom of the tube bay. 4. Connect DMM (set to read mV) with alligator leads, reference common lead to center pin (pin2) on molex connector CON2 and positive lead to pin1 on CON2.
5. Take amplifier off of STANDBY with no signal, adjust mini-pot (PR1) closest to pin that the positive lead from your DMM is connected to and set it to the mV voltage that is listed in the chart below. 6. Repeat steps 4 & 5 for pin3 and until both pin1 and pin3 mV are the same.

BIAS CHART mV SETTINGS
(pin1 and pin3)

DSL50 45mV TSL60/1/2 80mV
DSL100 90mV DSL401 1.375V
TSL100/122 90mV DSL201 .675V

Eoin Madsen

JimiTime wrote: »

Thanks guys, much appreciated. One thing that was touched upon was the biasing. Is there a DIY guide to it, or do you need a techie to do it? My bros an electroics whizz, does not deal with amps and stuff, but do you reckon he'd know what to do, if DIY is unwise?

Thaks again guys,
J.

Biasing has to be done with the amp on, and usually requires putting your hands inside, so it's something I'd recommend against by default. Plate voltage in your amp is around 400-450Vdc and could kill you quite easily if you put your hands in the wrong place. Part of biasing involves measuring this voltage exactly, so even if you use probes to minimise contact with the amp while it's on, you still have an unfixed high voltage wire running into your multimeter.

And even when the amp is off the filter capacitors can potentially hold anything up to 450 volts.

On the other hand, I do it all the time, and I'm hardly qualified. So far I've only touched live wires twice, and neither was fatal. I spent months and months reading about it before I ever got inside an amp though, and my sanity is questionable for numerous unrelated reasons.

JimiTime

Brilliant. Just ordered my JJ-tesla vales from Watford Valves. Thanks for the advice. I think my bro will be alright for doing the biasing. However, if not, can you recommend someone in Dublin, or surrounding, that could do this?

Eoin Madsen

Actually, I can't. I just do it myself, so I never found out in the end if there was anyone around that did it. Your best bet is probably to ask in Musician Inc. If they don't have someone, they might know someone.

JimiTime

Just another word of Thanks for the advice. Got my shiney new valves from watford valves. My bro is coming over tonight to do the biasing. He's een warned to wear thick rubber souled shoes:D. If you don't here back within 2 days, I've become part of the circuitry of a TSL 601:D

Voodu Child

JimiTime wrote: »

Just another word of Thanks for the advice. Got my shiney new valves from watford valves. My bro is coming over tonight to do the biasing. He's een warned to wear thick rubber souled shoes:D. If you don't here back within 2 days, I've become part of the circuitry of a TSL 601:D

Al put up a picture of the back of his TSL100 a few days ago, and you could see the 3-pin biasing molex was accessible from the back of the amp (without opening the chassis). If the TSL601 is the same it should be a pretty safe and straightforward job.

-=al=-

i forgot to get that spare tube today >.<

i got 4 hrs sleep and i had a test today, it was rough, ill def get it tomorrow

JimiTime

Horaaaah!! New tubes installed and biased. And now I can bias myself. Result!

Jelly 292

Ya, You can Bias my amp now if you like:D

-=al=-

yeah and sort out my tsl pls

Eoin Madsen

voodoo_child wrote: »

Al put up a picture of the back of his TSL100 a few days ago, and you could see the 3-pin biasing molex was accessible from the back of the amp (without opening the chassis). If the TSL601 is the same it should be a pretty safe and straightforward job.

Handy. Is there a B+ tap on it, or are they assuming that the voltage is what they expect it to be?

Voodu Child

Eoin Madsen wrote: »

Handy. Is there a B+ tap on it, or are they assuming that the voltage is what they expect it to be?

No, they're just using assumed values of about 450V B+ and 25W Pa. Their suggested values get you 'thereabouts' - but because it's so accessible and simple, you can literally tweak it +/- on the fly by ear.

Eoin Madsen

Tweaking on the fly would be nice. I think I prefer a 1959 with a slightly cold bias, but I've never had the patience to check properly.

Our mains voltage can vary by as much as 10V though, so I would not be too hot on the idea of taking an assumed voltage. Even if they predicted correctly and the amp is 100% in exact spec without any deviation (which is practically impossible), the B+ could vary by 20Vdc purely on the ESB. But I guess people get by with Mesa's etc just fine, so the difference probably doesn't matter to most people.

Voodu Child

Eoin Madsen wrote: »

But I guess people get by with Mesa's etc just fine, so the difference probably doesn't matter to most people.

Well, i'd hope most techs do have enough cop on to use their ears (and/or actually go in and get B+ for those actual tubes).

I think marshall's logic is just to keep the 'average' tweaker from going anywhere near the inside of the chassis.

I don't think of biasing as an exact science anyhow, most methods have their drawbacks or innacuracies, I think Pa is always an assumption for most people anyway, and like you say, the power supply plays a part too. Even if you take an actual B+ today, +/- 10V in a differerent part of the country or different time of the day will render your 'exact' biasing a little off anyway.

So yeah, i think if you can get 90% to a 'correct' bias, and then just tweak yourself by ear it's a reasonably good solution.