using a power amp as a bass head w/ a pre amp

jaredcarman · #1 12-23-2010, 10:45 PM

ok. so i need someone to school me. im on the road a lot. ive gone through enough bass heads now that i am done paying a g or more for nice gear that gets broken and ****ed up. replacing tubes for 300 or more. ive had almost every head that interests me and im over it. i want to run a power amp with some rack pre amps and use that as my set up for now. sooo my questions are..

what can my svt handle and can it not handle? break down the ohms watts thing for me. whats too big and what am i looking for?

the plan is a power amp and a sans amp tech 21 rack mount.

this is the power amp that i was looking at. is there other stuff i should check out? if this is too much power is it possible to just keep it turned down? someone school me!

http://www.google.com/imgres?imgurl=...ed=0CCAQ9QEwAQ

80'sRocker · #2 12-23-2010, 10:54 PM

Power amps are supposed to run full vol, at least last I knew. If you are playing metal/hard rock (or anything really), try the BBE Bmax Bass pre-amp as an alt to the Sansamp (although a great unit as well)

Antares · #3 12-23-2010, 10:57 PM

Sounds fine to me. Im assuming when you say your SVT, your referring to your cab. Which I'm guessing is an 8x10?

If so, i believe they're rated 800 watts at 4ohm. That would work perfectly with that power amp as its 750 watts/4ohm per channel. You than have the other channel as basically a spare amp. It seems you can only mono bridge (use both channels together) for 8 ohms. So i dont think you can do that. Someone else probably can confirm.

As for tech 21 rack, the RBI can come close to some nice SVT tones.

jaredcarman · #4 12-23-2010, 10:57 PM

im pretty set on sans amp for now. just need to figure out if this samson would blow up my bass cab. and then what i should look for instead. thanks for the response though. yes its metal/hardcore.

jaredcarman · #5 12-23-2010, 10:59 PM

what is this rbi that you speak of? yes ampeg svt 8x10 is the cab. also. the two knobs. that means its two channels? so if i wanted to run two 8x10s i could no problem?

i have sans amp pedal now..how would i run the pedal into the power amp? im going to go and try it out tomorrow.

fourstringburn · #6 12-23-2010, 11:04 PM

If your talking the 810 svt cab it can handle up to 1600 watts. I run 2- 810 cabs into a 1500 per channel power amp driven by 2 Ampeg SVP-PRO preamps. That's 1500 watts at full driven power to each cab. Most power amps are rated down to 2 ohms so you can use 2 cabs at 4 ohms equaling a 2 ohm load. Make sure the one your interested is rated as such before you run a 2 ohm load.

Bottom line, I love having more power than not enough...but you need more speakers to disperse the sound otherwise all that big power is wasted.

fourstringburn · #7 12-23-2010, 11:07 PM

My rig...

Antares · #8 12-23-2010, 11:09 PM

Quote:

Originally Posted by jaredcarman

what is this rbi that you speak of? yes ampeg svt 8x10 is the cab. also. the two knobs. that means its two channels? so if i wanted to run two 8x10s i could no problem?

i have sans amp pedal now..how would i run the pedal into the power amp? im going to go and try it out tomorrow.

Yes, you could power two 8x10s with that power amp.

The tech 21 sansamp RBI is basically their bass driver DI pedal in rack form, with extra mid control.

http://www.tech21nyc.com/products/sansamp/rbi.html

To run to the power amp i believe most sansamp pedals have 1/4 output and xlr output. You will have to see what the inputs on the power amp are. Should be able to use one or the other though.

jaredcarman · #9 12-23-2010, 11:13 PM

this is great info. thanks everyone. fourstringburn..you run both of those cabs with that head? how does it sound? what are some other rack things i should check out. do you play in a band?

fourstringburn · #10 12-23-2010, 11:36 PM

Yeah, both cabs with that head. It is not only loud , but really tight and punchy sounding and no lie, if you stand close at high volumes, I get a sense of vertigo from your whole body being absorbed by all that low end power that only 2 SVT 810 cabs can produce.

As for rack effects that is a personal preference. I use 1 preamp for my main sound and use the other for distortion when needed. I blend the 2 preamps with a small mixer and pan the main preamp stereo and the other preamp set for distortion on 1 mono side so I never lose the original bass tone since I find most distortion units thin out the bass tone. I do use a radial A/B amp selector pedal to switch between preamps or use both in combination.

The only sound processing I use is a compressor but I mainly use only the limiting function to keep from overloading the input stage of the power amp.

fourstringburn · #11 12-23-2010, 11:37 PM

A better look at my rig...

will33 · #12 12-24-2010, 12:37 AM

If you want to go that way, use a QSC RMX1450 and the preamp of your choice. An Alembic F-1 is a good choice as are many others.

Son of Bovril · #13 12-24-2010, 01:18 AM

It is not a problem to overpower your cab, but you do have to be aware that you can push it past it's limitations and do damage. If you keep an ear out for when it starts to distort and keep the volume below that you will have no problems...

jnewmark · #14 12-24-2010, 08:02 AM

Another choice of pre/pedal would be the VT, which alot of users say cop the feel and vibe of an Ampeg head. I would personally go with one of the lightweight power amps made by Crown or QSC.

PDGood · #15 12-24-2010, 08:19 AM

When tube amps get loud they get warmer sounding and then go into distortion. That's how you know you're approaching the peak volume; and if you're wanting to protect your hearing (some do and some don't) it's a good indicator. The thing about using ultra-clean power amps is that you don't get those warning signs.
I got to play through the Allman Brother's bass rig back in the day and it was powered by a couple of Crown power amps. Brutally clean, but had its own sound. Would take some getting used to for me, but I can see how it would work in some situations. Expect plenty of clean power and very little warmth - somewhat similar to GK heads.

Popps · #16 12-24-2010, 09:20 AM

One thing you might want to look into is that the power amp has independent channels. That way if one side fails you can just switch inputs/outputs to the other side. I have used Crowns for the past 30 years. I would recomend sticking to brands that have road history, QSC, Crown, Crest, etc. Can't speak for Sampson.

Mingo Sanders · #17 12-24-2010, 09:24 AM

Quote:

Originally Posted by jnewmark

I would personally go with one of the lightweight power amps made by Crown or QSC.

This.

pnut166 · #18 12-24-2010, 09:29 AM

Quote:

Originally Posted by 80'sRocker

Power amps are supposed to run full vol, at least last I knew.

?????

cableguy · #19 12-24-2010, 10:06 AM

I run my RBI through a Carvin DCM seies power amp. Mines an older one but the newer ones are pretty damn light.

Son of Bovril · #20 12-24-2010, 03:01 PM

Quote:

Originally Posted by PDGood

...Expect plenty of clean power and very little warmth - somewhat similar to GK heads.

There is absolutely no reason why a pre/power rig couldn't have warmth to it. Just because it doesn't have a tube power section doesn't mean it couldn't sound exactly the same...

Just listen to some of the samples recorded of the Tech 21 VT Bass compared to recorded samples of a Vintage SVT by members of this forum. If half of us can't tell the difference do you think the average audience member could?

I've played and owned big tube heads and I prefer the SS poweramp rigs for one reason, and it is a personal factor in my case (besides the weight): I dislike the way my tone changes every time I increase the volume on a tube amp... I like to set my sound for a gig and then be able to increase or decrease the volume of the amp as required during a show, but with a tube amp, everytime I change the volume (and this happens more so at high levels) my tone changes due to either pushing the pre or power section harder.