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SVT tube tone without the sag?

A

Aharon

Jan 23, 2008
128
0
#1
I've had a look into this and I'm still not 100% sure precisely which parts I would be looking to change or how much they are but here goes.


Loving the tube harmonics and rich tone but not loving the "sag" / pokeyness when pushed. Nor the low end response for that matter.
Its an SVT 2 Pro head. Are there economical mods that can be done to achieve these results? Some people are saying to change the caps, but others seem to be saying changing the power supply itself would be more effective. This is all new to me.

or perhaps an SVT VR would have an improved low end response and headroom in terms of sag.

Is it even possible to improve much beyond the stock performance?

Any thoughts?
 
#2
The easiest way to tighten things up is to add more/larger filter caps to the power supply. It's easy to do as long as there is the physical space for it in the chassis.
 
#3
thankyou JGR.

is this what I would be looking at?
[Invalid or Expired Link Removed]

they seem to do a newer/alternate version. v1.2.


how much performance increase can I expect out of one of these kits, and what other options are there for a tighter sound that wont compromise harmonic content / tone?
 
#4
the fliptops kits are pretty close to the stock values for vintage SVT's. i personally don't care to change the tone of tube amps by raising the values of the caps. it usually stiffens them up too much for my taste and often makes the amp a bit more harsh sounding. part of an SVT's charm is it's compression and sag. IMO, it sounds to me like you need more power (a different amp), not modding the one that you have.
 
#5
thanks for the input john.

I own both an svt 4 pro and an svt 2 pro. I wish I could somehow combine their strengths. The svt 2 has rich harmonics and great natural drive. The svt 4 has plenty of headroom, tight lows and more "stable" overall sound.

I recall basoballs saying he did some mods to his svt 2 pro and got good results, but ofc I'm looking to get facts/opinions from as many people as possible on this.
 
#8
Is it even possible to improve much beyond the stock performance?
Click to expand...

The honest answer is probably not all that much since headroom is your problem. You can spend hundreds of dollars on minor improvements but nothing will be the drastic increase in output you'll be looking for. At absolute best, after a lot of work and money invested, you'll be able to squeak by. You have a mass of responses another thread telling you the same thing and I've heard the same thing 100 times over from guys who know a lot more than I do while I was on the same quest myself.

Again, your SVT would be plenty loud if you didn't insist on using that Ultra Lo switch on the amp. That switch might as well be labeled "invisible in the band mix" on these heads and that's coming from a fan of them. Have you tried rolling back your bass knob significantly while playing to help quell the wasting of all of it's power on low end? The highest I've ever run a bass knob on an Ampeg is "noon". I usually have the bass at 10 o'clock on my SVT's. When using 610's of ported Bag End cabs, my bass knob was always at 9 o'clock.
 
#9
The cab is most certainly a bad match. Ported 610 warwick cab, likely to have sub-par efficiency.

With the ultra low pushed in I roll off the lowest slider on the EQ down about half way and I roll the bass knob back to about 10 o clock. The drive knob is also up to about 11 o clock which naturally tames the low end a bit also. Agreed, with the EQ and knobs all set flat, the ultra-low is overkill. Works well in the mix, although in boomy clubs i'll compensate to taste.

The amp is not being driven into growl/distortion at this point. Wasn't sure if the dynamic range / sag was headroom related or not because the sounds coming out of the cab were mostly clean and I was not pushing it as hard as I normally would.

I recall briefly owning a Mesa 400+ and while I didnt like the tone/character of the amp, it seemed more responsive than the SVT. Didn't want to give up on the 2 pro so soon as I got it only recently, but perhaps its inate characteristics just arent my thing.

Band is doing a gig next week where I'll be borrowing another guy's 810e cab. I guess I'll bring the svt 2 pro down to see how it changes things.

All further suggestions welcome.
 
#10
I can't comment on your 6x10 cabinet's effeciency although it would seem that many drivers would have a decent effeciency rating. What impedance is the cab and do you have your amp set to this impedance?

I disagree about a vented cab with an SVT head; my TL606 sounds very good (although not all that loud) but my vented Berg sound very good and plenty loud (although not as loud as an SVT cab).

The fact that your 4 pro gets loud and has good tone with your cab sounds like the asnwer to the question; your sound requires LOTS of power at least with your existing cabinet. Your idea about trying a complete SVT rig is a good one; try with the tone controls flat and without the ultra low. Rather tan adding any EQ for bottom, try removing top.
 
#11
Aharon said:
thankyou JGR.

is this what I would be looking at?
[Invalid or Expired Link Removed]

they seem to do a newer/alternate version. v1.2.


how much performance increase can I expect out of one of these kits, and what other options are there for a tighter sound that wont compromise harmonic content / tone?
Click to expand...

I think the main filters in your amp are probably a pair of 100uF 450 V caps in series, PC mount - if so, you need something like this:

Invalid Link Removed

Do a search on Digikey under aluminum caps 450 V or higher, whatever value you want - 220 uF would double what is in there and is probably a good place to start, though more wouldn't be unreasonable as it it is a bass amp, and there isn't much filtering in there in stock form. Try to find something with the same physical dimensions.

There are lethal voltages in there so take it to a tech if you aren't experienced in this sort of thing.
 
#13
as others have said, the bass boost switch is NOT your friend on an SVT. if you go out into the crowd and listen to yourself, with the room's boundary reflections, your tone will have a TON of low end without using it. IMO, all it does is cut mids and use up your available power. it might sound good to you on stage but i think that all the audience will hear is undefined and distorted mud.
 
#15
johnk_10 said:
as others have said, the bass boost switch is NOT your friend on an SVT. if you go out into the crowd and listen to yourself, with the room's boundary reflections, your tone will have a TON of low end without using it. IMO, all it does is cut mids and use up your available power. it might sound good to you on stage but i think that all the audience will hear is undefined and distorted mud.
Click to expand...

+1
 
#16
i often read on this forum that tube heads sound best with a sealed cab. IMO, that's a myth. they do or can sound nice (at least i like 'em & have several of them). they usually feel a little tighter and more focused, but one of my favorite sounding 100% tube rigs is a Sunn 2000S with one or two Sunn vented 200S or 2000S cabs with JBLS, so to me the sealed cab with tube heads theory goes out the window.

my SVT sounds great thru my sealed 810, 4x12 V4 and fender 2x15 (also sealed) JBL K140 cabs, but it sounds equally great thru my whappo jr, 1212/6, Sunn 200S and my most recent scratchbuilt dual 3015 cab (which are all ported). to me, it's about the actual cab & drivers and not whether it's sealed or not.
 
#17
The sealed statement is a generalization. I have played probably 2 vented cabs that I've thought were good with the svt. Every sealed cab has sounded great. That warwick cab is about as bad of a match for an svt as I can think of. Let us know what you think after using the 8x10. That 2 pro is a good amp but doesn't have enough in common with a real svt. I have used/owned/own both as well as most of the other ampeg stuff. Get a 70's svt and sealed cab and then let me know what you think. You'll probably think "screw this heavy stuff, Im getting a shuttle 9.2 and an nv610". :smug:
 
#20
rodl2005 said:
Ha ha. Yes, try it with the Ampeg 810-FAR better match imo.
& remember that ultra lo button cuts LOTS of mids & adds (iirc) +2 db of 'bass'. So it's really a 'mid-cut' or 'smiley-face' eq button.
I'd lose it, & use the eq to get a similar flavour if that's ur bag.
Click to expand...

+1

The ultra low button is an evil tone killer. Avoid it and the ultra hi, just use the knobs (a little goes a long way) .
 

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