SVT-IIpro questions/issue

flyingfinbar · #1 10-03-2010, 08:32 PM

First post here, it seems like a great place with many knowledgeable people!

Well, I just bought my first all tube amp, an SVT-IIpro.

Once I got it home, I realize that it wasn't as loud with the same settings as a CL I was borrowing from a friend. Overall, it just seemed a little less "alive," if that makes any sense. There was a discrepancy with the volume between the two, and the tone seemed off with the II pro. Not as gutsy, and the low end rolled off much harder.

It was then that my electrical engineer drummer, while looking at the PDF of the owners manual, asked me to tell him which LED's are lit up on the back of the amp. I looked, and there are no LED's lit up. According to the manual, this means bad voltage, bad biasing controls or bad tubes. The voltage is fine, which leads me to believe it's one of the other two.

The previous owner had never changed the tubes and he had the amp for 4 years, which he had bought used. I'm thinking it very well could be the tubes.

I'm sure someone here can give me some insight. Is it common not to get a light on the LED's when there's a tube issue? I had the amp fully warmed up, powered on on standy with no instrument cable plugged into the input when I noticed there were no LED's lit.

I'm not too worried about a retubing, but how bad is it if there's a problem with the biasing LED's?

Any advice is greatly appreciated!!

kranahan · #2 10-03-2010, 09:35 PM

The LEDs come on when you turn the standby off. Do all lights come on then?

Jerrold Tiers · #3 10-03-2010, 10:17 PM

There is NO high voltage unless standby is not engaged, in other words unless the amp is set up in playing condition..... So no biasing lights will be on. It HAS to be ready to play for anything to be lit.

What's on THEN?

flyingfinbar · #4 10-04-2010, 04:19 AM

Wow, thanks guys. I have to be honest, and it's rather embarrassing, I didn't bother to check if the lights were on when standby wasn't engaged before I moped and plotted revenge for about ten minutes.

The amp is currently at my rehearsal space, so I gotta wait until much later before I check out what colors we're looking at.

I can already tell this place is great, thanks again!

jastacey · #5 10-04-2010, 08:21 AM

Here's how I have set the bias on my SVT II Pro , let the amp warm-up for about a half hour, flip off the stand-by switch ( make sure the amp is connected to a speaker cabinet ) adjust the bias pots slowly,till the green lights up, you will have a little play in the green lite till it gets to the red lite stage ... I run the master volume at 3 o'clock, drive at around 8:30/9:00, and use the gain as the volume control

eastcoasteddie · #6 10-04-2010, 09:16 AM

Quote:

Originally Posted by jastacey

...I run the master volume at 3 o'clock, drive at around 8:30/9:00, and use the gain as the volume control

In contrast, I have my gain set to about noon (for an active bass and -dB switch enabled; with a passive bass, I set gain to 1-2pm), drive control at about 1-2pm and use the volume knob to control volume. It gets plenty loud.

flyingfinbar · #7 10-07-2010, 11:33 AM

Quote:

Originally Posted by jastacey

Here's how I have set the bias on my SVT II Pro , let the amp warm-up for about a half hour, flip off the stand-by switch ( make sure the amp is connected to a speaker cabinet ) adjust the bias pots slowly,till the green lights up, you will have a little play in the green lite till it gets to the red lite stage ... I run the master volume at 3 o'clock, drive at around 8:30/9:00, and use the gain as the volume control

Well, thanks to everyone's advice here, it seems that I've made sense of it all!

First off, the bias lights work just as they should, with both staying green until I hit a note, at which point they flash red for a moment.

I also played around with the settings a little (I was totally misusing the drive knob, which wasn't present on my friends borrowed CL), and using jastacey's suggestion as a starting point, found "my" sound.

This is the first time the sound I've heard in my head for so long has actually come out of my own amp

(tears of happiness).

It really sounds amazing, I haven't been this thrilled about "gear" since I saved my pennies and bought a fretless Ric about ten years ago!