15" speaker recommendations for vintage SVT

[traynorbassmate]

My main rig is a vintage SVT and 410HLF, it sounds fantastic.
For smaller gigs I use a u.s.a made 15E cab, however the original speaker (200W max @ 8ohms) wouldn't handle the low frequencies very well...best described as the speaker "farting" typically when playing the low E. I was convinced the amp was overpowering the speaker.

I replaced the speaker with a 15" Eminence Kappa(?) 450W/4ohm, but the cab still sounds lousy when playing loud enough to compete in a 3-piece rock band.

Any ideas or suggestions?

thanks!

[billfitzmaurice]

Originally Posted by traynorbassmate

I replaced the speaker with a 15" Eminence Kappa(?) 450W

Watts mean nothing. Low frequency output is limited by the driver excursion, xmax. That is what you need to be concerned with when comparing different drivers, of course doing so with a response modeling program like WinISD, to be sure that the drivers you're considering are compatible with the cabinet you intend to load them in.

[B-string]

If the cab you have is not compatible with the driver, the driver (speaker) will unload at low frequencies and "fart out" no matter how good the specs are. Typical 115 may only be half as "loud" as a 410 in pre-made bass cabs BTW.

[JimmyM]

You're probably asking too much of a single 115. If you had two of them, it would distribute the load better and maybe not fart out so early, plus you wouldn't be running it at 8 ohms, which you really shouldn't do with a vintage SVT.

[Sartori]

Indeed, use two 15"s with an SVT, not one. I get a lot out of single 15" when I need to, but I'm not pumping a huge amount of low end.

And also, as Jimmy says... the SVT isn't supposed to be run with an 8 ohm load.

[RickenBoogie]

yup, them guys are right, a single 15 is just not enough for what you're asking of it.

[traynorbassmate]

Thanks everyone. I thought manufactures don't release specs such as xmax...I guess I'd need to get lucky and find someone who has successfully swapped speakers in this exact cab.

I've played the amp through a 215 and loved it...but my goal here is a relatively portable/small gig rig (maybe the 90+ lbs amp is already starting off on the wrong foot...) and while I can load the 410hlf on my own, sometimes the gigs don't warrant the big cab...if it can't fit in the car or the stage!

My upgraded 15" is 4ohm.

Aside from losing headroom, why should the SVT not be run at 8ohm? I get it from an efficiency point of view, but it isn't harmful - right?

[Stick_Player]

Originally Posted by traynorbassmate

Thanks everyone. I thought manufactures don't release specs such as xmax...I guess I'd need to get lucky and find someone who has successfully swapped speakers in this exact cab.

Reputable manufacturers do.

The speaker NEEDS to be matched to the cabinet - as stated above.

[traynorbassmate]

If the speaker was matched to the cab, all correct specs and whatnot, would I note an improvement in sound? Or is it impossible to have the SVT running through any single 15 for the original stated application...in other words, is this venture worth it.

[JimmyM]

Originally Posted by traynorbassmate

Aside from losing headroom, why should the SVT not be run at 8ohm? I get it from an efficiency point of view, but it isn't harmful - right?

Depends. Unlike SS amps, tube amps have an output transformer that converts the signal into something the speaker can use. They generally like to see the impedance they're specified for. Using a higher impedance than specified can heat up tubes and the output transformer and damage them prematurely, especially if you like to crank them into the red.

Now have I used SVT's at 8 ohms and not had any troubles? Yes I have. But I barely have any volume going because we don't like loud stage volume, and they were always rentals. Never would I dream of doing it with my prize 1969 (a REAL 1969, not one of these 70's or 71's masquerading as a 69) SVT.

And if you do decide to get a second 115e down the line, they have to be daisy chained into one input since yours is vintage. Newer ones are OK to run both directly from the head, but not old ones.

[JimmyM]

Originally Posted by traynorbassmate

If the speaker was matched to the cab, all correct specs and whatnot, would I note an improvement in sound? Or is it impossible to have the SVT running through any single 15 for the original stated application...in other words, is this venture worth it.

Not really, no. Ampeg already matches their cabs to the speakers. You might be able to squeeze a little more out of it with a neo, and you might like the voicing of a different speaker better, but I don't think the little extra power handling you might get out of a neo is worth it, and you can always turn the knobs to get a different sound. If you want to be loud, you need a cab that can handle it, and a single 115 is probably never going to make you happy like two will. That's pretty much the end of story.

[traynorbassmate]

Fair enough, thank you so much for your input.

Can you explain the output daisy-chain in more detail?

First, just to clarify, the head is designed to run at 4ohms (one 4ohm cab) or 2ohms (two 4ohm cabs)...I thought you plug each cab into the SVTs two separate output jacks. fyi my amp is straight edge blackline, 1974 best guess.

15E's are 8ohms. Since you suggest the daisy-chain I'm guessing that they're wired so that they will hookup to each other in parallel, bring the load down to the 4ohms (as opposed to series, up to 16ohms). Why can't each cab be run separately into the head's outputs?

I don't see myself getting another 15E. Ultimately, if gigging goes in the desired direction I'd want another u.s.a 410hlf (two 4 ohm cabs, to run at the 2ohm target). How would that tie in with your explanation?

Thanks again

[JimmyM]

Originally Posted by traynorbassmate

Fair enough, thank you so much for your input.

Can you explain the output daisy-chain in more detail?

First, just to clarify, the head is designed to run at 4ohms (one 4ohm cab) or 2ohms (two 4ohm cabs)...I thought you plug each cab into the SVTs two separate output jacks. fyi my amp is straight edge blackline, 1974 best guess.

Beautiful head.

15E's are 8ohms. Since you suggest the daisy-chain I'm guessing that they're wired so that they will hookup to each other in parallel, bring the load down to the 4ohms (as opposed to series, up to 16ohms). Why can't each cab be run separately into the head's outputs?

Because in old SVT's, each speaker out tripped its own separate 4 ohm tap in the output transformer. If both are used at the same time, it expects to see two 4 ohm loads. But if you plug two 8 ohm loads into it, each transformer tap will see two separate 8 ohm loads. So you have to daisy chain two 8 ohm cabs into one input so the transformer sees the correct load. And yes, they daisy chain in parallel.

I don't see myself getting another 15E. Ultimately, if gigging goes in the desired direction I'd want another u.s.a 410hlf (two 4 ohm cabs, to run at the 2ohm target). How would that tie in with your explanation?

Plug one into each speaker out and you're good to go. And stack them vertically and turn off the bottom tweeter for best results. Heavy and a PITA lift? Yes. But it sounds so much better to go vertical that it's worth it.

[beans-on-toast]

Originally Posted by traynorbassmate

Aside from losing headroom, why should the SVT not be run at 8ohm? I get it from an efficiency point of view, but it isn't harmful - right?

It can be harmful, depending on the amp. In general, connecting a higher speaker load to a tube amp is a bad thing. Some amps can take it and they can run all day like this without any problems, others can't. It depends on the transformer specs, the design of the power amp stage, and in some cases how hard the amp is pushed. Some people report that they run their SVT's at 8 ohms and get away with it.

There isn't a simple way to explain this, the issues are complicated. One of the things that the output transformer does is to match the output impedance of the tubes to the speakers.

The output transformer, serves to reflect the impedance of what is connected to it. What does this mean? If you double the impedance load at the output, the impedance at the input of the transformer also doubles. If you have a 4 ohm output on your transformer and connect a 4 ohm speaker, the tubes are going to see an impedance which is matched with where they were designed to operate. If you connect an 8 ohm speaker to a 4 ohm transformer tap, the tubes are going to see an impedance which is 2X what they were expecting to see. Strap on some heavy weights and go for a run and see what it does to you. This affects the operating point of the output tubes, the distortion characteristics and headroom, the power output, tube life, the tone of the amp, etc.

The extent to which all these things are affected depends on the amp. Some people do this on purpose because it gives them the tone that they want.

[traynorbassmate]

Glad to know these little tid-bits!

If vertical is king, I suppose it would make sense to get one 810 instead...but that is a discussion/daydream for another day.

Beautiful it is. I've never played another vintage model, though mine received favorable reviews last week when I lent it out as backline (w/410) to Lee Fields and the Expressions bassist Nick Movshon (black keys, amy winehouse). He mentioned that he's played many an ampeg bass amp and having come across a few duds in the vintage realm, he enjoyed playing through the rig and noted that it performed well. Kind words that I pray were genuine! In contrast to his remarks, I did have trouble dealing with the feelings of inadequacy and "how can I ever play this amp again" having seen this guy with jaw-dropping talent simply level the room...

oh well! thanks for the info.

cheers

[JimmyM]

An 810e sounds completely different from two 410HLF's, though I tend to agree with you that it does make more sense, especially when you deadlift that HLF!

And I'm sure that dude was being genuine.

[Sartori]

Why is an 810 a daydream?

You can find them used quite inexpensively. Not much more than a 410HLF, I wouldn't think.

Is it a "doesn't fit" issue?

[nysbob]

I play mine through 8 ohm JBL 15"s in parallel (two cabs). For gigs that only require I cab, I use a V4B and switch it to 8 ohm - similar sonic characteristics to the SVT and if you only need 1 15" you don't need all that power either.