New to Valves/Tubes need help!!

60jbass91 · #1 09-19-2010, 01:24 PM

i recently just bought a vintage sound city b200 plus amp it is in full working condition except for one significant problem one of the KT88s is bust, i thought it would be a simple replacement but i went on a valve website and about 6 different types of KT88 came up from winged c to jj so i was just wondering what would be best for me.
part of this post was also just so i could show off about my new amp which is my first all valve amp

iv finally joined the club of great tone and back problems haha

Mr. Foxen · #2 09-19-2010, 01:36 PM

Important bit is what is in it already, and are they also on the way out. Best to replace in sets, but probably wanna aim for a same brand at least.

mongo2 · #3 09-19-2010, 01:51 PM

I find it interesting that back in the '60s and '70s when a power tube went bad it was replaced. Nobody cared about replacing sets, much less matching them as has been the trend for a while. Somehow we managed to carry on.

Now it's apparently more complicated than in the good ol' days.

JimmyM · #4 09-19-2010, 01:55 PM

Quote:

Originally Posted by mongo2

I find it interesting that back in the '60s and '70s when a power tube went bad it was replaced. Nobody cared about replacing sets, much less matching them as has been the trend for a while. Somehow we managed to carry on.

Now it's apparently more complicated than in the good ol' days.

not for me. i still do it

but i do at least try to match them in pairs. still, i'm not above replacing just one in a pinch. replacing the whole set when the rest work, though, is to get ripped off. in a sound city, the most you should have to replace for a single power tube is two of them.

no idea about brands, though winged c and jj are both pretty respected.

60jbass91 · #5 09-19-2010, 02:59 PM

well i will have a look then maybe i will post some pics since you kind sirs gave your time to reply to me i must warn you it is in less than perfect condition haha but im deffinitely going to have it re upholstered atleast.

mongo2 · #6 09-19-2010, 04:11 PM

Seriously, one thing you should definitely have checked and most likely replaced are the power supply capacitors.

NecroticImbecil · #7 09-19-2010, 05:08 PM

It's never a bad idea to have a tech go over an old tube amp before you start using it regularly. When I got my Sound City, it had some problems, so I had a tech fix it up. He did a bunch of things to it, including replaceing the stock power tubes with JJ KT88s, and it's worked fine since.

Do check to see the brand of KT88s it has in it presently. I was able to sell the Kt88s that came in my Sound City for more than the amp itself cost me.

JimmyM · #8 09-19-2010, 05:15 PM

i totally agree with the amp tech if you're going to gig it. ancient tube amps will hold up just fine on the road, but they do need serviced now and then. if one tube is out, there could be other problems. also, as mongo said, caps do get old. do it now while it'll be cheap rather than later where you could take out a transformer.

Calaverasgrande · #9 09-19-2010, 07:58 PM

Ditto, find a good tech in your area and stick to them like glue. A good tech (that you are already a regular with) will go teh extra mile to make you happy. My tech has even held his door open for a couple hours past his closing time so I could grab my amp on teh way to a gig.

BassmanPaul · #10 09-20-2010, 08:38 AM

Quote:

Originally Posted by mongo2

I find it interesting that back in the '60s and '70s when a power tube went bad it was replaced. Nobody cared about replacing sets, much less matching them as has been the trend for a while. Somehow we managed to carry on.

Very true but nowadays folk are interested in getting the most out of their amps. Back in the day amps tended to be set a little cold. That way you could just about bung any old tube into the amp. It's still ok as long as you check that the new tube is not red plating.

If you want the best from your amp then a matched set is the best way to go.

Paul

Alex1984 · #11 09-20-2010, 11:00 AM

Congrats! JJ and SEDs (the REAL Svetlana) both seem good, Sovtek and Svetlana are reasonable too and a bit cheaper.

60jbass91 · #12 09-22-2010, 04:22 AM

from what iv read the caps on old sound citys are pretty rubbish so i suspect they will probably need replacing, and it only has four power tubes so im considering just replacing them with jjs would be a different story if i had got the back up purchase to this which was a mesa 400 haha

BassmanPaul · #13 09-22-2010, 11:22 AM

Quote:

Originally Posted by 60jbass91

from what iv read the caps on old sound citys are pretty rubbish so i suspect they will probably need replacing, and it only has four power tubes so im considering just replacing them with jjs would be a different story if i had got the back up purchase to this which was a mesa 400 haha

With respect, punctuation is our friend. It makes this jumble of words into something meaningful!

Paul

jackcheez · #14 09-22-2010, 11:27 AM

Quote:

Originally Posted by 60jbass91

part of this post was also just so i could show off about my new amp ...

Not without pics.

kosmicwizard · #15 11-17-2010, 11:33 AM

**Staccato** · #16 11-17-2010, 11:57 AM

On the subject of replacement tubes...

What I learned in the process of buying tube amps and a Hickok Tube Tester over the last couple of years...there are very few people on forums that I would either ask or accept advice about which 'different' tube to buy. Advice is cheap, but so many of us repeat what we've heard without intimate knowlege of a subject, eh? This is a complex subject.

An excellent tube source is Doug's Tubes, and upon hearing what equipment you've got, and perhaps a bit about your goals with the amp, he can offer
suggestion(s) for a replacement tube.

Sartori · #17 11-17-2010, 03:27 PM

No pics, no new amp.

AwkwardLoudness · #18 11-17-2010, 03:33 PM

Will you post any internals pics of that old Sound City B200 Plus? It's probably a Mark 4 era Sound City since it's labeled "plus". These amps have active preamp circuits, so I've re-wired the pre-amp tag board to be passive like the earlier Sound City amps....sounds much better and less noisy.

For KT88s, I suggest Gold Lion reissue or Winged C =C= (reissue of the old Svetlana), but J/J and Valve Art will work fine too and cost a little less.

I concur on having a good tech look at the amp. It will need new electrolytic capacitors if they're original and likely bulging.

60jbass91 · #19 11-17-2010, 05:32 PM

well it may surprise you all to know that it has all of its original GEC's in with that lovely made in england stamp. It also has its original partridge transformers. Im not gigging at the moment so i only bought the one electro harmonix replacement. i havent had a tech look at it yet cos im low on cash, however i have pulled a wiring diagram off the net, and upon first inspection I have discovered that the middle control for the EQ is'nt even connected.

I will post pics if someone tells me how haha

Mr. Foxen · #20 11-17-2010, 06:09 PM

Photobucket is pretty easy image hosting, upload to there and it prepares a copy and pastable link in IMG tags for forums.

Have a good look around the electrolytic caps (big jobs, look like batteries) for leaking out white stuff, that is the thing that will need sorting almost definitely.