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Power amp - Setup Question

funkydanbass

funkydanbass

Sep 6, 2007
979
62
Melbourne, Australia.
#1
Thanks to everyone for the help on my last post. Continuing on with that line of questioning:

I am intending running two seperate preamps through one power amp, via a Line mixer.

If Im running to four ohm cabs off a poweramp, is there any sonic difference between running it in stereo four ohms a side and running it bridged a 2 ohms?
I mean, can I have the exact same signal going to both cabs running stereo? If Im running a mono signal from the line mixer to the poweramp how would I best setup this speaker configuration?

Is there any power amps that can actually run at 2 ohms bridged?

Thanks in advance,

Daniel Kinnaird.
 
#2
Hi,
No sonic difference between the 2. You should pick the mode that gives you best wattage to power handling of the speaker.
Crown makes some amps that can run in parallel mono which will go down to 2 or even 1 ohm depending on model.

Cheers,
Paul
 
#5
Bridged mono into 2 ohms is electrically equivalent to 1 ohm per channel. The Crest 10001 is the only amp I'm aware of in the past 10 years or so that can do that.

You're better off looking for an amp with adequate power into 4Ω per channel.
 
#7
Well they won't see the exact same signal since presumably you're using each preamp to create 2 slightly (or vastly?) different sounds. One channel of the power amp would get the signal from one preamp, and the other channel would get the signal from the other.

What exactly are you trying to accomplish with the two pramp setup?
 
#8
I want to have completely different EQ's for my fretted and fretless basses. I have tried numerous amps and setups and when I find the *perfect* tone for my fretted bass Im not satisfied with the tone on my fretless, (EQ setup). I have attempted to purchase several dual channel heads. My Eden WT1205 blew up the day I got it home, (lets not talk about the 7 months it took to get my money back after discovering no replacement was available in Australia). I looked into the Epifani heads, but the supplier who was supposed to bring them into Australia took 6 months to find out they weren't gong to be distributing them. I didn't like the tone much anyway. etc etc etc etc....


So what you're saying is each channel of the stereo power amp would basically represent a preamp. So preamp 1 to speaker cab 1, preamp 2 to speaker cab 2?

Is there any peice of gear that can effactively sum the two preamp's without degrading signal or posing any impedance, buffereing problems??
 
#10
funkydanbass said:
I want to have completely different EQ's for my fretted and fretless basses.
Click to expand...
I'd recommend leaving the EQ on the amp flat and using two EQ pedals, one for each instrument. Leave them connected in series, and click one on and the other off when you switch instruments. Alternately, there are pedal switchers (with EQ) designed for this purpose such as the EBS MicroBass II or a couple of products by Radial.

funkydanbass said:
Is there any peice of gear that can effactively sum the two preamp's without degrading signal or posing any impedance, buffereing problems??
Click to expand...

Sure, lots. Almost any mixer will work, and there are some small mixers out there. If you want something simpler and more rugged than a mixer, Rolls and ART make some nice utility boxes for this sort of thing. Look into the Rolls Invalid Link Removed, Invalid Link Removed, the ART Promix, etc.
 
#11
Using EQ pedals before a preamp is not something I want to do. Most of them have inadequete EQ and poor quality components. Doing this still means that both basses are going through the same preamp, ie. if I run the DB680 it still means that the fretless will passing through all those tubes, and I think part of the sound I want for the fretless doesn't involve tubes. I have the radial bassbone and have been using this in to my
SA200. I like my fretted basses through the SA200, but no amount of tweaking on the bass bone, or other EQ pedals will change that I don't like the fretless through it.

Furthermore, I have no intention of running 2 high quality pre's through a poor quality mixer that will degrade the signal and most likely provide buffering and impedance issues to boot! I am not familiar with the Rolls and ART gear and will certainly check them out.

I have spoken to peple at RANE, re the SM26S which I thought would suit this application, they thought not. And the guys at Whilwing regarding there AB box, whom advised against using it citing impedance issues.

Cheers,

I didn't think it was such an uncommon thing for touring bass players to use a combination of preamps in there setup....
 
#14
funkydanbass said:
Can i just run two preamps into a poweramp? No mixers or A/B boxes in between?
Click to expand...

Yes. If you run it in stereo. Preamp A into side A of the power amp and Preamp B into side B of the poweramp. Since you want one for each bass, plug the fretted into Preamp A and the fretless into pre-amp B and mute the one you aren't using. But you won't be able to use both speaker cabinets in one channel unless you feel like powering down and switching the speaker outputs between songs.
 
#16
funkydanbass said:
Ok, so it can't be done with 2 preamps direct to the poweramp!

Now, is anyone 100% aware of a quality product that can handle two pre's in and one signal out that buffers, matches impedance, doesn't colour tone or degrade it?
Click to expand...

That would be a mixer.
 

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