JCM 2000 TSL602 - Tube Advice...

[MarshallMatt]

Hi Guys,

My trusty JCM 2000 TSL602 2x12 combo has done a tube :cuss so it's replacement time. I just pulled out the originals and they are as follows: -

- Svetlana Electron Devices Inc EL34 (Made in Russia)

I play mainly blues and hard rock (Zeppelin, Guns , pub rock) and I quite like the tones that get with these (the 2 x 12 cab is running Wolverines)

So, it would appear that my choices are: -

- JJ Tesla Electronics EL34 Power Amp Valve
- Svetlana EL34 SV Power Amp Valve
- Mullard EL34 Power Amp Valve
- Electro-Harmonix EL34EH
- Ruby EL34B STR Power Amp Valve
- Groove Tubes EL34M
- Winged C EL34

Also, given that I'm replacing both - is there a benefit to having the two new tubes 'matched'?

Based on the styles of music I'm into, can anyone recommend something from the above options that would suit?

Thanks in anticipation!

Matt

[dukealexan]

If you like what was in there why change and yes get a matched pair, the bias on the TSL602 is external and easy to do. The bias test point has 3 pins, the center is negitive and the 2 outside are positive, you only need to connect to one of the outside pins as there is only one trim pot that controls both tubes so having a matched pair make sure they both pull same power.

[Sully807]

I like Ruby's myself

[ClassicRock88]

I have JJ's in my 800. I typically use them because they are inexpensive and have a reputation for being somewhat rugged by EL34 standards. In my Adams V50 I have Electro-Harmonix. I like them and they have a bit smoother top end than the JJ's, but I actually think that wide open the Adams doesn't seem as loud. The JJ's typically give a pretty good "oomph" even though I think that they have a harsher top end. I have been told by an amp tech that I trust that Winged C's are the way to go. Aren't Winged C's just selected and rebranded Svetlanas? Either way they are both supposed to be good tubes and the guy told me if you are willing to drop the change on them get the Winged C's. That being said I can buy a matched set of JJ's for the price of a single Winged C... So it is up to you what you want to do and what your priorities are. If you beat on the amp routinely (which I do my 800) then I would say JJ's for price and being able to keep on tickin' but if it is mostly bedroom playing and recording then I would spring for more expensive tubes because you won't wear them out as fast and they will probably sound a little sweeter. My $.02.

[MarshallMatt]

Thanks everyone - really appreciate your advice.

Two final questions if I may. Because I know not much about how amps work (apart from the basics), is there anything else that I should replace when I swap-out the two power tubes? Also, I keep hearing/reading about biasing. Can I simply plug the new power tubes into the sockets and it'll be good to go or do I have to do this biasing thing?

Thanks heaps

[ClassicRock88]

You will need to replace the preamp tube called the "phase inverter". This is usually the closest preamp tube to the power tubes and it splits the signal from the preamp in two. There are generally recommended tubes that are balanced to be phase inverters.

Biasing is important. If you replace a tube with the same class from the same brand (i.e. a Tesla tube rated at an 8 replaced with a Tesla tube rated at an 8), then generally you do not need to rebias. But it is stil a good idea to check it. Go get a book called "The complete guide to guitar and amp maintenance" by Ritchie Fliegler. It is published by Hal Leonard and if you want to do your own maintenance it is some of the best money that you will ever spend. You will need a multimeter to measure the bias and then you will adjust the bias pot (near the test points on your amp) to get the bias in the range recommended for your amp. You can either look up the recommended bias for a TSL 602 on the internet or use some of the charts out there (or in the book) that estimate the correct bias based on your plate voltage and type of tube.

[burnsy]

I would go with a matched pair of Svetlana Winged 'C's. Get the bias set correctly.
If the Phase Inverter tube ain't broke, leave it alone, it'll last for years.

[dukealexan]

The TSL602 is one of the easiest amps to bias. On the rear there is a black plastic rectangular cover to the bias test pins and trim pot. If you don't have one get a digital multy meter, doesn't have to be expensive $10-20 will do. Also Radio Shack has these mini test lead clips adptrs that work great http://www.radioshack.com/product/index ... Id=2062221 they will clip onto the test pionts so you don't have to hold them. There are 3 pins the center one is neg and the 2 outside ones are positive, the 2 outside one are connected so you can use either one. Make sure the amp is off and connect the meter to the pins. There is also a trim pot to the right of the pins. Get a small philps screw driver plastic if you can, you do have to be carefull not to touch the wrong things and create a short. Test turning it left and right to get a feel for it, when you are ready turn it to the left which is like turning it to almost zero. Set the meter to 200mv dc, turn the meter on. Then put the amp in standby and turn her on, turn all controls to 0. Let her warm up then turn the standby off. You should get a low reading on the meter like 20 something. You are reading both tubes at once and we want to set them to 80 milivolts dc. So start turning the pot to the right slowly till you are aprox there. Let her sit 5-10 minutes and check again as the tubes warmup the reading can move so you may have to set it again, doesn't have to be exact. You can leave the meter attached and on and play her to see if you like the way it sounds. You can run them hotter (80-90) or cooler (70-80), but MARSHALL says 80. When your done turn her off then disconect the meter and your ready to go.

[MarshallMatt]

Thanks so much for the great advice - I really appreciate it. Looks like I now have a job for the weekend

Cheers,

Matt

[ClassicRock88]

Good luck! Be careful and have fun!

[chee]

New here, but thought I would throw in my advice and ask how the original poster made out with the new PT's, how they sound, etc.

My main amp is a TSL602 and I love it. The wolverine speakers are crap, trust me, after I put in an Eminence Tonespotter and Black Powder I realized how great the amp could sound. I was really hesitant at first but am nothing but happy with the change. Good preamp tubes are also a must. Not necessarily old stock (though I love a mullard in v1) but a good v1 and v2 bring the tone to life and show the amps true versatility. I play blues/rock, big Hendrix/SRV tones. My preamp is as follows: v1-I63 mullard, v2-long black plate raytheon, v3-ge 12ax7, v4-ge 12ax7a

I also did a cap mod to reduce the fizz on the OD channels, really simple to do, though I don't think it is totally necessary. I use very little gain on those channels so it helps for my tone I guess. Completely reversible in about 30mins anyways

One note also, the bias of 80mv is for both sides COMBINED. You want no more then 40mv on either side and it is important to check both as even matched tubes can be a little bit off. I like the bias at 35-36mv per side, above that gets harsh to my ears and below that loses something. I also recommend letting the amp warm up for 5-10 mins on standby, check the bias, then play it for a good half hour, then check it again.

Cheers, sorry for bringing back a dead thread and I hope I didn't yammer on too much

[MarshallMatt]

New here, but thought I would throw in my advice and ask how the original poster made out with the new PT's, how they sound, etc.

My main amp is a TSL602 and I love it. The wolverine speakers are crap, trust me, after I put in an Eminence Tonespotter and Black Powder I realized how great the amp could sound. I was really hesitant at first but am nothing but happy with the change. Good preamp tubes are also a must. Not necessarily old stock (though I love a mullard in v1) but a good v1 and v2 bring the tone to life and show the amps true versatility. I play blues/rock, big Hendrix/SRV tones. My preamp is as follows: v1-I63 mullard, v2-long black plate raytheon, v3-ge 12ax7, v4-ge 12ax7a

I also did a cap mod to reduce the fizz on the OD channels, really simple to do, though I don't think it is totally necessary. I use very little gain on those channels so it helps for my tone I guess. Completely reversible in about 30mins anyways

One note also, the bias of 80mv is for both sides COMBINED. You want no more then 40mv on either side and it is important to check both as even matched tubes can be a little bit off. I like the bias at 35-36mv per side, above that gets harsh to my ears and below that loses something. I also recommend letting the amp warm up for 5-10 mins on standby, check the bias, then play it for a good half hour, then check it again.

Cheers, sorry for bringing back a dead thread and I hope I didn't yammer on too much

Hey Chee,

Glad you love your 602 as well. For some reason - they seem to get such a bum rap on here most of the time. I just love mine for it's versatility.

Anyway - re: amp mods - I decided that it all got a bit too hard. I can play a guitar and make an amp scream but when it comes to tinkering with them .... an man's gotta know his limitations!

I got my local amp tech onto it and we ended up throwing in a set of Electro-Harmonix EL34EH. I contemplated a few other options but in the end, I thought I'd try these and see how they performed. Let's say I'm not going to change them anytime soon. Really well balanced and stable. And great value too!

Agree on the speakers. Wolverines seemed to be ok for the studio work I was doing but when I needed to really drive the amp hard - they just weren't giving me what I was looking for. Decided to shell out the cash and got a pair of Vintage 30's in there. Did contemplate Greenbacks but the 30's were just tighter and seemed better to my ears in a live situation.

So - there you have it. That's all I got!

Keep on rockin'