Early '70s Magnavox SVT sounds disappointing?

[Stone Soup]

Originally Posted by jwhjwh

I found this youtube demonstration of a similar era SVT: http://www.youtube.com/watch?v=EUyyB2OjzuMThat's more or less exactly the tone I'm getting.

Man, there's nothing wrong with the sound of the SVT in the video.

[B-string]

I really should go get my good headphones but that amp sounded like the bias was set too hot. IME
A tip for your tech: The voltage method for setting bias printed in the chassis is not accurate and not a good plan for new production tubes.

[jwhjwh]

Originally Posted by Stone Soup

Man, there's nothing wrong with the sound of the SVT in the video.

I didn't mean to indicate that there was, just that that tone seemed to disappear when playing with the full band.

I know, I know, believe me, this must sound crazy, and it goes against every orthodoxy I've come to believe.

[jwhjwh]

You guys are probably going to crucify me for saying so, but if you can believe it, my friend's father sold me the SVT for a hundred dollars.

He didn't care how much it was worth, and was glad someone was taking it out of his garage.

I was on cloud nine. Funny how things work out sometimes, though.

[Roadkill]

Originally Posted by jwhjwh

I know, I know, believe me, this must sound crazy, and it goes against every orthodoxy I've come to believe.

Not really - solid state amps cut better, that's why they gained favor in the 80's . Mostly it's a matter of taste. But you should be able to dial up an acceptable sound through a 6x10 with an SVT no prob. Maybe yours is biased cold or somethin'...

[Stone Soup]

Originally Posted by B-string

I really should go get my good headphones but that amp sounded like the bias was set too hot.

I don't know how you can tell that without knowing how the sound made it's way to the video and with whatever youTube does to the files on upload... I'll take your word for it, though. If you could explain what it is you heard that made you think the bias was hot, I'd like to know. I'm always interested in learning new things.

[B-string]

Originally Posted by jwhjwh

You guys are probably going to crucify me for saying so, but if you can believe it, my friend's father sold me the SVT for a hundred dollars.

He didn't care how much it was worth, and was glad someone was taking it out of his garage.

I was on cloud nine. Funny how things work out sometimes, though.

I think that is awesome. When running properly if the SVT is still not your sound, no harm, no foul. You should be able to get back the money invested pretty easy.

[BawanaRik]

Check the drivers like it been mentioned. SVTs and in general the monster Ampegs amps have very different tone controls than most other amps. It's like sitting a Porsche for the first time. Spend some time and find out what does what.

[B-string]

Originally Posted by Stone Soup

I don't know how you can tell that without knowing how the sound made it's way to the video and with whatever youTube does to the files on upload... I'll take your word for it, though. If you could explain what it is you heard that made you think the bias was hot, I'd like to know. I'm always interested in learning new things.

At low volume too much crunch in the low end, loss of sustain and he appeared to get breakup at too low of input volume. Crossover distortion was apparent to my ears. Low mids had a "distant sound". Just ear training from too many decades repairing amps.
Cold bias I would hear breakup (crossover distortion) on note decay.

[jwhjwh]

Am I correct in thinking that an amp like the B2RE has a flatter power section?

Reason I ask is that that amp seemed to be able to duel with the very loud guitar, whereas with the SVT it wasn't possible to find a tone setting that put the bass quite as a front and center.

Interestingly, the reason my B2RE keeps blowing up apparently has something to do with the temperature sensor and fan. I'm wondering if I can wire it to always run the fan at full bore, but that's a question for another day, I suppose.

And to be clear, I don't think the SVT sounds bad, at all! I just was surprised that it sounded so strangely incompatible with this particular band, in this particular practice space. Never meet your heroes, they say.

[JimmyM]

Dang good deal! I'll give you double that if you don't want it, and I'll even pay for shipping!



OK, so here's two things:

1. Don't know if you used JJ 12DW7's or not, but they are crap. A good NOS tube in V1 like an Amperex, Sylvania or an RCA is only a little more than a JJ and it's much better. It's not a huge difference in tone but it makes a little difference in the sparkle of the highs in my amp. YMMV. And the JJ 12DW7's are made like an afterthought...very sloppy workmanship in every one I've seen.

2. With all the ultra switches off and the EQ at noon, it's a big party at 125hz and gradually tapers down as you go across the spectrum. This is the flattest setting I got out of my 69 SVT and most SVT's I play, including new ones:

Bass 11:00
Highs 2:00
Mids 3:00 @ 800hz
Ultra switches off

This will vary slightly from amp to amp, but it's as flat sounding as I could get it in comparison to the Markbass Little Mark II I used to have, which is quite flat with all knobs at noon and filter knobs off. You may not care for that sound either, but I think it's a good platform to get started.

Also, I disagree about tube amps not being able to "cut." Nobody ever has any problem hearing me "cut" when I use my SVT or B-15.

[JimmyM]

Originally Posted by jwhjwh

Am I correct in thinking that an amp like the B2RE has a flatter power section?

Reason I ask is that that amp seemed to be able to duel with the very loud guitar, whereas with the SVT it wasn't possible to find a tone setting that put the bass quite as a front and center.

Interestingly, the reason my B2RE keeps blowing up apparently has something to do with the temperature sensor and fan. I'm wondering if I can wire it to always run the fan at full bore, but that's a question for another day, I suppose.

And to be clear, I don't think the SVT sounds bad, at all! I just was surprised that it sounded so strangely incompatible with this particular band, in this particular practice space. Never meet your heroes, they say.

Bah...

Anyway, you're right that the B2RE is a flatter response amp. I don't know what it measures at with knobs at noon, but Ampeg's old chief engineer who's a regular on here said it was designed to be flatter and to appeal to those who don't typically like Ampeg amps and wanted something flatter and more solid state sounding.

Also, you can hardwire the fan to be always on, but I haven't a clue how to do it. I did, however, do that in this old SWR SM-500 I used to have so it can be done.

[jwhjwh]

Originally Posted by JimmyM

1. Don't know if you used JJ 12DW7's or not, but they are crap. A good NOS tube in V1 like an Amperex, Sylvania or an RCA is only a little more than a JJ and it's much better. It's not a huge difference in tone but it makes a little difference in the sparkle of the highs in my amp. YMMV. And the JJ 12DW7's are made like an afterthought...very sloppy workmanship in every one I've seen.

I'll have to ask my amp tech about that. I'm not quite sure, but I'd guess that it's probably a JJ 12DW7, since I'm not sure who else is making them these days.

Originally Posted by JimmyM

2. With all the ultra switches off and the EQ at noon, it's a big party at 125hz and gradually tapers down as you go across the spectrum. This is the flattest setting I got out of my 69 SVT and most SVT's I play, including new ones:

Bass 11:00
Highs 2:00
Mids 3:00 @ 800hz
Ultra switches off

Very much appreciated! I will try this as soon as I can.

[zachoff]

Everyone's ears are different but like others have said... That doesn't sound right.

After spending that much on one tech I'd look for another to get a 2nd opinion. I have Svetlana Winged C powers and the original Magnavox pre tubes in mine ('76) and I absolutely love it... Although it does have a weird hum when I plug one signal into both channels. Haven't figured that one out yet. Yay, 70s electronics! Always a fun rasslin' match.

My settings are all pretty flat too. Mid switch at 800, all super high and super low switches off, bass at noon, treble at 11, mid at 2.

[B-string]

Example of 12DW7/7247 still available without going JJ's http://www.tubesandmore.com/products/T-12DW7_7247-GE

[jwhjwh]

For twenty bucks that looks like it'd definitely be worth trying

[JimmyM]

GE's are usually pretty good, too. Originally they came with Sylvanias, which are also a good value on the NOS market. But you can pay out the wazoo for a special edition NOS RCA or Mullard, too. I don't go for them, I just go for the regular old Sylvanias or Amperexes these days.

[bigbottomend]

Another option would be to try KT88's instead of 6550's ? Working correctly, SVT's will blow other amps to the wind.

I played a usual gig the other day with mine and 8x10. Another bassist had a markbass big bang and a 6x10. It was the local xmas jam night for most of the musicians in the area where i live.

We never directly played one against the other but after we had both played i was overwhelmed with guitarists coming over to me to compliment me on the tone and power of the SVT. Most said that it sounded "alive and filled out the room with energy".

[BawanaRik]

In many cases the 12 dw7 can be replaced with a 12ax7. You might notice a bit more gain.

If you like less gain try the 12au7. I've been rolling few 12au7s since hearing folks on TB liking them. You might like them.

[JimmyM]

Originally Posted by BawanaRik

In many cases the 12 dw7 can be replaced with a 12ax7. You might notice a bit more gain.

If you like less gain try the 12au7. I've been rolling few 12au7s since hearing folks on TB liking them. You might like them.

Not in old SVT's. If it calls for a 12dw7, it needs a 12dw7.