Power Amp Rigs

[jezzaboy]

Cheers Jack.

[Clarky72]

[quote name='Jack' timestamp='1489238928' post='3255388']
With pedal preamps there can be a volume issue. The pedals have a rather limited amount of gain they can provide for a few reasons, mainly that they're limited by the 9V power supply but also they're designed to work in front of standard amps rather than power amps. You'll get sound either way, but I've seen the pedal output volume maxed and the gain controls on an amp maxed and still the signal LEDs are just barely being tickled.

You really have two options, one is to find an amp with the lowest input sensitivity that you can, ideally around 0.775V. Option 2 is to use another gain stage to boots the pedal before the power amp.

If you use the RBI you'll likely have a wider choice of suitable power amps.

Oh sorry, I should answer your question. QSC PLX??02, pick the one you feel you need. I have a 1602 that does 300W a side into each of my Barefaceds, and the possibility of 1600W into both if I wanted. They have either a 1.2V or 1.7V input sensitivity I think, depending on the model, so you may find your RBI will sing and your VT Bass a little on the quieter side.
[/quote]
Thanks Jack, really helpful advice! I love Basschat, there's always someone who knows the answer....

[NancyJohnson]

[quote name='Clarky72' timestamp='1489232240' post='3255331']
So I have a VT Bass pedal, and a Sansamp RBI. Thinking about pairing one of them up with a power amp rather than just using them in the effects chain and ditching the amp I'm using.

What amp do you recommend for a Sansamp? Lighter the better ideally
[/quote]

I use a Matrix GT1000FX. It's dual channel, 1000w bridged and weighs 4.1kg...you'll need to factor in the weight of the rack and peripherals, it's still pretty light. It fits in a shallow Gator rack too. My old Ashdown ABM was around 15kg. I've had no issues driving the Matrix with the RBI or when I use a floorboard, a BDDI, VTBASSDI or GT2. It's rock solid; last night it was used by five bands for nearly six hours.

[url="http://uk.matrixamplification.com/gt-1000-fx-2u.html"]http://uk.matrixampl...1000-fx-2u.html[/url]

[quote name='Fisheth' timestamp='1489264184' post='3255646']
Was looking at getting the new Geddy Lee Preamp. The word suggests it's based on the RBI, if that's the case, does anyone know of any recommended power amps for it?
[/quote]

The Geddy Lee is dual channel (although the production model will have the option of a single output). [edit] Its a slightly modded RBI for dirt, along with a channel for cleanish low end with some saturation. This unit is high on my shopping list this year (and I'll move my RBI on). Likewise, no qualms about routing this through the Matrix either.

Edited March 12, 2017 by NancyJohnson

[spectoremg]

[quote name='Jack' timestamp='1489238928' post='3255388']
With pedal preamps there can be a volume issue. The pedals have a rather limited amount of gain they can provide for a few reasons, mainly that they're limited by the 9V power supply but also they're designed to work in front of standard amps rather than power amps.
[/quote]Thanks Jack. Without this wonderful site I wouldn't have known that.

[Guest bassman7755]

[quote name='Fisheth' timestamp='1489264184' post='3255646']
I'm really new to this, is there a chance that things just won't be compatible with each other?
[/quote]

Simplistically you can pretty safely assume that anything with rack ears will work with anything else with rack ears - so anything designated a "preamp" and that comes in a rack mountable form factor will work with any rack mountable poweramp.

[Saved]

Nub question,but why not to ask?
If a pre-amp DI pedal,goes to the power amp from the DI out,is possible to have vol issues?

[Jack]

Possible. Likely even. Easy enough to try though?

The way to think of these things is this: How's your DI box/pedal preamp [i]designed[/i] to work? Something like a Sansamp is designed to output the XLR to the PA system and the 1/4" to the amp. In both cases you have a gain stage before the power amp.

The PA system chain is designed to be sansamp > mixer > outboard gear > poweramp
The bass amp chain is designed to be sansamp > bass amp preamp > bass amp power amp

In both chains you've got some serious stuff going on before you hit the power amp. None of this means it won't work! None of this means it won't even be fine! It just means that if you're not using gear the way it was designed to be used you may run into some issues. In this case, what tends to happen is quite simple: anything that can be powered by a 9V battery doesn't have enough gain to properly power the rather serious power amps. Is this a rule? No! Does it mean you won't have a perfectly acceptable rig if you do this? No!

This stuff is I think quite important if you are looking to buy some of this gear and you can't try it out beforehand. Maybe then you can worry about and learn all of the minutiae. If, on the other hand, you have the stuff and you fancy a play then just do it. It'll make a bass-shaped sound either way.

Edited March 14, 2017 by Jack

[Saved]

I am talking about the eden wtdi.
If you se how is the room with my rig and how the cables are all togather..you atr gonna hit me :-P

[jay-syncro]

I think someone is selling a Matrix GT1000FX and Basswitch preamp in the classifieds..

*ahem*

[markstuk]

[quote name='spectoremg' timestamp='1489354133' post='3256341']
Thanks Jack. Without this wonderful site I wouldn't have known that.
[/quote]

Also different power amps have different input sensitivities.. QSC's are known to need a high signal level to drive them - from what I remember 1.5v at unity and there is a mod to make this .775 v

[paul_5]

[URL=http://s1221.photobucket.com/user/paul_510/media/Peg_zpso87nif9m.jpg.html][IMG]http://i1221.photobucket.com/albums/dd471/paul_510/Peg_zpso87nif9m.jpg[/IMG][/URL]

Dug my old Laney power amp out and wired put this together.

Nice. Lots of 'heft' and great for metal.

[Clarky72]

[quote name='terocious' timestamp='1487683507' post='3241782']
SansAmp RBI and RPM (parallel) to the Peavey IPR1600 power amp.

[url="https://postimg.org/image/xk9xkk1ev/"][/url]

How is the RBI and Peavey? Good sound?
[/quote]

[Wolverinebass]

From experience, the Peavey IPR1600 is crap. It has a low cut filter on the back for 120hz. Even with that turned off I don't believe that the cut off is much lower. Anaemic is a pretty good way to describe it. One of the channels on mine failed and it was replaced under warranty, but I didn't trust it again and got my Yamaha p5000s which although only 100w a side more completely kills. Also, my rig is midi controlled so it was the same settings with the same cabs and lo and behold I actually got some bass.

Okay the Yamaha isn't light, but that'd be the only reason anyone would get that Peavey because the tone suck on it is horrific.

Edited March 16, 2017 by Wolverinebass

[Clarky72]

Really? Arse.

I just want a clean power amp that wont colour my sound, ideally around 500W, light would be nice, 2U or less.

[NancyJohnson]

[quote name='Clarky72' timestamp='1489672921' post='3258856']
Really? Arse.

I just want a clean power amp that wont colour my sound, ideally around 500W, light would be nice, 2U or less.
[/quote]

Read my post about the Matrix GT1000. It ticks all your boxes.

[Clarky72]

I've looked at the matrix, its listed as a guitar power amp though, which puts me off slightly.

[Clarky72]

What I like about the Peavey is the super compact size and weight, 2U and a shallow rack case. I've looked around on 'that other forum' too and no-one seems to have anything bad to say about it. The irritating blue glow can be dealt with.

[Jack]

I hate to argue with somweone who's had first-hand experience, but I can't see why that Peavey wouldn't be a good amp. Everything else Peavey makes is, and it's specs say it's -3dB is like 5Hz. Don't worry about the 120Hz hpf, it's not really a hpf it's a crossover for PA duty.

[Wolverinebass]

[quote name='Jack' timestamp='1489767782' post='3259702']
I hate to argue with somweone who's had first-hand experience, but I can't see why that Peavey wouldn't be a good amp. Everything else Peavey makes is, and it's specs say it's -3dB is like 5Hz. Don't worry about the 120Hz hpf, it's not really a hpf it's a crossover for PA duty.
[/quote]

Yeah, but I was talking about the sound with that disengaged. There was virtually no signal below about 85hz. One good thing about having a spectrum analyser in my rig with a 31 band eq is that this stuff can be tested very easily.

It's my experience and I'm only disappointed that it didn't work out for me.

[dmccombe7]

[quote name='terocious' timestamp='1487683507' post='3241782']
SansAmp RBI and RPM (parallel) to the Peavey IPR1600 power amp.

[url="https://postimg.org/image/xk9xkk1ev/"][/url][url="https://postimage.org/"]image url upload[/url]
[/quote]

Just curious how your rig is wired up with the 2 pre-amps and what cabs do you use. Is the power amp bridge for mono output.
It just sounds like a really interesting set up.

Cheers
Dave

[NancyJohnson]

[quote name='Clarky72' timestamp='1489765641' post='3259664']
I've looked at the matrix, its listed as a guitar power amp though, which puts me off slightly.
[/quote]

What? It amplifies. That's it. It's tonally as transparent as you can get. There's one up in the For Sale section. Get in.

[krispn]

Just playing devils advocate but I thought power amp rigs were all about transformers and heft rather than light weight class d power sections? I'll get my coat.

In saying that I'm just about to rehearse with the TTE 500 cause tonight's rehearsal room is a pain to get into so light weight wins the rig choice this time round!

[NancyJohnson]

[quote name='krispn' timestamp='1490033592' post='3261618']
Just playing devils advocate but I thought power amp rigs were all about transformers and heft rather than light weight class d power sections? I'll get my coat.

In saying that I'm just about to rehearse with the TTE 500 cause tonight's rehearsal room is a pain to get into so light weight wins the rig choice this time round!
[/quote]

I know I keep harping on about the Matrix, but I just tired of pushing my pre-stage through the effects return of an Ashdown ABM; size or class was unimportant, so long as it was loud, light and I could rack it up, I was happy.

Irrespective of the amplifier class (it's not Class-D), the Matrix weighs in at about a 1/3 of the Ashdown and bridged is rated at 1000w, so the menage of weigh/output/size doesn't really stand up.

[krispn]

That's me told 😉

[NancyJohnson]

nOW GO
[quote name='krispn' timestamp='1490088403' post='3261991']
That's me told
[/quote]

Now go and stand in the corner.