SVT issue

bassboysam · #1 09-16-2011, 05:00 PM

My magnavox era SVT is sounding kind of mushy lately. Seems to distort a little early and the overall tone is muddier. The lows seem to be struggling to come out clear and always sound distorted. I had it biased about 6-9 months ago and the tubes (4 year old sovtek kt88) were in good shape then which leads me to believe its not a tube issue. Could these symptoms be related to the caps? Still the originals in there.

Alex1984 · #2 09-16-2011, 05:10 PM

It'd be a good idea to get them recapped if your sound is getting weak. You could check your pre-amp tubes.

JimmyM · #3 09-16-2011, 05:51 PM

If you still have the original caps, I'd say it's probably about time.

**B-string** · #4 09-16-2011, 07:30 PM

The caps are PAST due for replacement.

bassboysam · #5 09-16-2011, 07:36 PM

Thanks guys, that was my guess. Would poor caps induce early distortion?

JimmyM · #6 09-16-2011, 07:44 PM

They could, especially after 40 years. I usually get crackling when mine have gone bad. Getting any crackling?

bassboysam · #7 09-16-2011, 07:45 PM

No crackling just a loss of punch and flabby low end.

**Lazarus.Bird** · #8 09-16-2011, 07:54 PM

My guess would be that your Canadian power plants have maple syrup coming out of your AC outlets!

**B-string** · #9 09-16-2011, 07:54 PM

The filter caps not only smooth the AC noise from the DC rails they also provide voltage reserves. No reserves, no punch, DC power rails dip at lower frequencies (get flabby and weak).

bassboysam · #10 09-16-2011, 07:55 PM

That's how we can afford to ship all our power to our southern neighbors.

Looks like I'll have to retire the SVT for a little while, how much does a typical cap job cost?

beans-on-toast · #11 09-16-2011, 08:44 PM

The recap cost can vary depending on what type of caps you have installed. Fliptops.net sells an SVT recap kit for $104.
Some people like FP-type caps similar to what was originally there. Sprague Atom caps are often used. Both these cost a little more.

How much bench time is kind of an open ended thing because it depends on what is done. While the amp is at the tech, it is good to have other things done at the same time. For instance, this could include a good cleaning, replacing the plate, screen, and cathode (bias) resistors, applying deoxit to the pots, jacks, and tube sockets, installing a 3 conductor power cord, checking the tubes, and setting the bias and balance. All this could take 5-6 hours.

Just replacing the caps could take 1-2 hours depending on how the job is done.

Some places charge a flat rate, others charge by the hour. Prices can vary. One thing for sure, a good tech who knows the amp is worth every penny that they charge. Spend some time to find out who locally does the best work.

grendle · #12 09-16-2011, 09:05 PM

Quote:

Originally Posted by beans-on-toast

The recap cost can vary depending on what type of caps you have installed. Fliptops.net sells an SVT recap kit for $104.
Some people like FP-type caps similar to what was originally there. Sprague Atom caps are often used. Both these cost a little more.

How much bench time is kind of an open ended thing because it depends on what is done. While the amp is at the tech, it is good to have other things done at the same time. For instance, this could include a good cleaning, replacing the plate, screen, and cathode (bias) resistors, applying deoxit to the pots, jacks, and tube sockets, installing a 3 conductor power cord, checking the tubes, and setting the bias and balance. All this could take 5-6 hours.

Just replacing the caps could take 1-2 hours depending on how the job is done.

Some places charge a flat rate, others charge by the hour. Prices can vary. One thing for sure, a good tech who knows the amp is worth every penny that they charge. Spend some time to find out who locally does the best work.

+10

If the caps are going its time for some major work before other things start to go. Spend the cash now or spend more later.