"Stereo" acoustic amps

BULLSPRIG · #1 12-19-2008, 01:03 PM

Do these amps do as advertised? Do they truly deliver a unique "stereo" sound that is distinguishable from a non-stereo amp? And what happens when you plug into a PA in a large auditorium? Is the stereo sound lost? Can a PA produce its own stereo sound?

I have jillions of questions and I'm brand new here. Please bear with me.

Herb Hunter · #2 12-19-2008, 01:29 PM

Quote:

Originally Posted by BULLSPRIG

Do these amps do as advertised? Do they truly deliver a unique "stereo" sound that is distinguishable from a non-stereo amp? And what happens when you plug into a PA in a large auditorium? Is the stereo sound lost? Can a PA produce its own stereo sound?

I have jillions of questions and I'm brand new here. Please bear with me.

In order for a stereo acoustic guitar amp to deliver stereophonic sound, it would have to receive a stereo signal from the guitar. I don't know of any guitar capable of doing that. Some guitars send out a pair of signals, one from each of two pickups but the sum of those two signals do not contain stereophonic information. They simply allow for separate equalization and effects.

The same applies to PAs. They have to receive a stereo signal in order to create a stereophonic image. At least the speakers of a PA are usually far enough apart to be capable of creating a stereophonic image. The speakers in an acoustic amp are too close together to accomplish that.

It is possible to synthesize a sterephonic sound. That would only be possible with speakers that are positioned far enough apart however.

Stereophonic sound creates a spatial illusion. When that is accomplished, the sound of various instruments appear to be coming from different points between the two stereo speakers. With a single instrument, stereophonic sound is not much of an advantage though a subtle feeling of depth may be apparent that would be missing from a monaural system.

BULLSPRIG · #3 12-19-2008, 03:14 PM

Wow, thanks. Makes sense. So when they advertise a "stereo" acoustic amp, they're just stating that it has 2 channels, capable of processing their own settings. Is that about right?

Herb Hunter · #4 12-19-2008, 03:27 PM

Quote:

Originally Posted by BULLSPRIG

Wow, thanks. Makes sense. So when they advertise a "stereo" acoustic amp, they're just stating that it has 2 channels, capable of processing their own settings. Is that about right?

Many amplifiers have two channels in the preamp whose combined output is sent to a single channel amplifier and single set of speakers. A stereo acoustic guitar amp has a two channel power amplifier and separate speakers for each channel.

BULLSPRIG · #5 12-19-2008, 03:33 PM

So, somewhere in the middle of my question. Thanks again. Let me present you with another question. The Carvin amp we discussed in another thread...

I notice it has an optional speaker cabinet accessory for an additional cost.

Suppose you had this amp, along with the additional speaker cabinet, on a fairly large stage, on opposing sides. Left and Right. I realize having elementary electronics knowledge, that his is essentially a "in-series" configuration, but would you think the sound would be superior over just a single Carvin amp minus the external speaker?

Herb Hunter · #6 12-19-2008, 03:42 PM

Quote:

Originally Posted by BULLSPRIG

So, somewhere in the middle of my question. Thanks again. Let me present you with another question. The Carvin amp we discussed in another thread...

I notice it has an optional speaker cabinet accessory for an additional cost.

Suppose you had this amp, along with the additional speaker cabinet, on a fairly large stage, on opposing sides. Left and Right. I realize having elementary electronics knowledge, that his is essentially a "in-series" configuration, but would you think the sound would be superior over just a single Carvin amp minus the external speaker?

I would expect the second speaker would improve the audience's experience because it would propogate the sound over a greater area. The good thing is that one can always add the second speaker later on.

Doubleneck · #7 12-19-2008, 04:09 PM

I have a Genz Benz 200 stereo and I always thought that the effects were stereo. If you put chorus or reverb it creates a stereo image in the effect. I have seen that work, running an effects box mono and then putting both lines in for stereo. It does make a difference but not sure the audience would really pick up on it.
Steve

alohachris · #8 12-19-2008, 04:11 PM

Aloha,

If you are interested in dual channel stereo live applications, then you might consider a dual source PA over a single source amp. In every way, it is much more flexible in terms of soundstaging, placement, quality and control - especially if you are using several sources or dual effects in stereo. Stereo amps are very limited in terms of room control because they are mostly single source - dual speakers in one box.

The only area in which a PA (mono or stereo) is not better than an amp across the board in terms of the quality of a live amplification system is portability. You have to carry and set up more gear with a PA. Soloists or small acoustic combos who don't mind the extra gear or who cannot compromise on sound and control prefer PA's. Those more concerned with schleppability playing smaller venues tend to champion an amp. It's as simple as that.

New systems such as Fishman's Soloamp apparently combine the best characteristics of both a PA and an amp.

Trust you own ears on which works for you.

A Hui Hou!
alohachris

FLDavid · #9 12-19-2008, 04:13 PM

Quote:

Originally Posted by Herb Hunter

In order for a stereo acoustic guitar amp to deliver stereophonic sound, it would have to receive a stereo signal from the guitar. I don't know of any guitar capable of doing that. . .

The Fishman Stereo Prefix Blender in the RainSong WS1000 has stereo capability, requiring the use of a stereo plug
There is a mono/stereo switch on the underside of the preamp chassis that (in the stereo mode) splits the undersaddle pickup & the internal condenser mic

Both my WA and HI RainSongs are so equipped
More recent RainSongs use the L.R Baggs system, but I'm unfamiliar with the Baggs' capability

sdelsolray · #10 12-19-2008, 04:53 PM

Stereo requires at least two sources, separate (usually identical) signal chains for each source, a mixing bus that blends all the sources left, right or anywhere inbetween, a dual mono power amp and two speakers.

A single source can be "stereo-ized" with a split of the single source into two identical signals then into a two channel delay, chorus, or a few other circuits, then to an optional stereo mix bus, then to a dual mono power amp and two speakers.

Herb Hunter · #11 12-19-2008, 05:55 PM

Quote:

Originally Posted by FLDavid

The Fishman Stereo Prefix Blender in the RainSong WS1000 has stereo capability, requiring the use of a stereo plug
There is a mono/stereo switch on the underside of the preamp chassis that (in the stereo mode) splits the undersaddle pickup & the internal condenser mic

Both my WA and HI RainSongs are so equipped
More recent RainSongs use the L.R Baggs system, but I'm unfamiliar with the Baggs' capability

The Fishman Stereo Prefix Blender is a two channel system as I described in my first post. It does not generate a stereophonic signal. One channel carries the signal from the piezoelectric pickup and the other channel carries the microphone signal. Admitedly, it is a technical distinction.

FLDavid · #12 12-19-2008, 07:56 PM

Quote:

Originally Posted by Herb Hunter

The Fishman Stereo Prefix Blender is a two channel system as I described in my first post. It does not generate a stereophonic signal. One channel carries the signal from the piezoelectric pickup and the other channel carries the microphone signal. Admitedly, it is a technical distinction.

I see your meaning now: stereo implying "spatial"
Certainly you're correct. . .

Sunbreak · #13 12-19-2008, 08:04 PM

Quote:

Originally Posted by BULLSPRIG

So, somewhere in the middle of my question. Thanks again. Let me present you with another question. The Carvin amp we discussed in another thread...

I notice it has an optional speaker cabinet accessory for an additional cost.

Suppose you had this amp, along with the additional speaker cabinet, on a fairly large stage, on opposing sides. Left and Right. I realize having elementary electronics knowledge, that his is essentially a "in-series" configuration, but would you think the sound would be superior over just a single Carvin amp minus the external speaker?

I have that rig, and it's more along the lines of "dual mono". It's just a small PA, but it's louder w/ the extension cabinet.

This discussion comes up quite a bit, but for live use I would stay away from anything but mono. It sounds like such a great idea, until you're the one in the audience getting a lousy mix from your seat.

Even the guitars w/ dual outputs are probably going to be mixed at the FOH and output to mono....