| Author |
Topic: changing over to solid state rectifier help |
Chris Erbacher
From:
Sausalito, California, USA
|
Posted 19 Feb 2006 4:27 pm |
|
| howdy, i'm in the process of tuning my amp (135 watt twin) to be what i want it to be, and one of the things i am doing is changing it over to being a solid state rectifier. any help before i go ahead and do this? is it just plug and play so to speak? any values inside the amp that need to be changed? the spongy thing has to go... |
|
|
 |
Jon Light
From:
Saugerties, NY
|
Posted 19 Feb 2006 4:40 pm
|
|
| Chris--a Twin already is SS. No rectifier tube in there. What are you looking at that you think is the rectifier? |
|
|
|
Chris Erbacher
From:
Sausalito, California, USA
|
Posted 19 Feb 2006 4:43 pm
|
|
| i feel pretty stupid... |
|
|
|
Jon Light
From:
Saugerties, NY
|
Posted 19 Feb 2006 5:25 pm
|
|
| Naw. What's the problem that's bothering you with the amp? You say spongy. Can you be more descriptive? Also, I know you've talked about it before but I forget--what speakers do you have in it? |
|
|
|
Andy Zynda
From:
Wisconsin
|
Posted 19 Feb 2006 6:42 pm
|
|
135 UL Twin sounds spongy?
You may have one weak tube, dragging the rest down. It may also have a marginal electrolytic filter cap in the B+ supply.
What type of output tubes are in there, and has the bias been checked?
A 135 watt twin should hit you in the face like a steel shovel.
-andy- |
|
|
|
Jim Sliff
From:
Lawndale California, USA
|
Posted 19 Feb 2006 7:42 pm
|
|
I'm with Andy -
Check/replace the filter and bias caps.
Check/replace the power and driver tubes and rebias the amp slightly on the cold side
Check/replace the preamp tube for the chanel you use
Check out your speakers for type and impedance match.
As stated, that thing should hit you like a ton of bricks. |
|
|
|
Chris Erbacher
From:
Sausalito, California, USA
|
Posted 20 Feb 2006 12:38 am
|
|
| okay, like a good little consumer soldier and general tone freak and overall detail warrior, i bought three weber books on amps, i have pretty much finished all of them. i am a man on a mission, it just is going to cost me a few more bucks than i anticipated (doesn't it always). anyway, the spongyness i am referring to is at higher volumes and i think it is just the difference between a tube amp and a solid state one, i am just going to have to get used to the feel of it when doing scale runs, sort of like a pillowy feel or boingyness, it is hard to decribe. i have jbl's in it, e-120's, might as well have a forklift too. it is plenty loud, and i went ahead and rebiased it to a slightly cooler setting and i'm getting more definition in the low end, a bit harder sound, i think that will help in cutting thru the mix. i'm having a split cab fashioned to break up the weight. now, i think this thing is pretty stock, which means that pretty much everything cap wise will be changed and all the tubes are different, bummer. now, i am a supremely extreme tone freak, and want a highly detailed sweetness to the tones i hear, i'm on a seemingly nonstop journey thru the annals of things i previously never thought i would be trying to understand. since i am new to the whole schematic and layout thing with amps ( i prefer a well labeled diagram), i am unsure of which one is the correct one to follow for my 135 watt twin, since it is otherwise unlabeled as such in the weber books. i have tried to match up the preamp tube types from right to left with the power tubes from right to left, but none of them match exactly. it has four 6L6 types in it, but none of them are the same exact types (6L6wxt+, 6L6 GC, 6L6B,, 6L6 S) the preamp tubes are from left to right (12AT7, 12AX7, 12AX7, 12AT7, 12AX7, 12AX7), they are all different. anyone use telefunken tubes in their twin? i'm told they are super great tone wise and last forever, but they are $225 a matched quartet. i think i am going to get teslas for the 6L6's, but in weber's book he says that a 7581A is also good for steel. does anyone have any experience with these tubes and steel? what did you have to change, i think he mentions that they are like 5 watts higher apiece than stock 6L6's. i'll start with tubes and go from there...thanks for the help. |
|
|
|
Donny Hinson
From:
Glen Burnie, Md. U.S.A.
|
Posted 20 Feb 2006 4:36 am
|
|
| The first thing yiou need is 4 matched 6L6's, or at least 4 that are the same brand! Having 4 different ones in there is kinda like having 4 different spark plugs in your car, and trying to tune it up so it runs decent (it probably won't). Until you have decent tubes in there, everything else you do is kinda pointless. |
|
|
|
Jerry Erickson
From:
Atlanta,IL 61723
|
Posted 20 Feb 2006 6:23 am
|
|
| Chris,I had to reread your post to make sure I read that you rebiased the amp. The schematic I have shows a 10K pot in the bias circuit that is a bias balance pot and not a bias adjust. I'm assuming that you did change that circuit over. |
|
|
|
Ken Fox
From:
Nashville GA USA
|
Posted 20 Feb 2006 9:01 am
|
|
I sent you a schematic for the 135 Watt twin. Plate voltage is close to 500 on these amps. I would strongly recommend JJ- Telsa 6L6GC tubes, they can handle it. Buy a matched quad from www.eurotube.com. He is a great guy to deal with. His relatives run the factory overseas, from what I have been told.
You will need to convert the bias to an adjustable type circuit, too. You can find that in the Weber books.
[This message was edited by Ken Fox on 20 February 2006 at 09:02 AM.] |
|
|
|
