Should there be any difference in what you hear? (Bi-amping again)

[jazzyvee]

Due to a lull in gigs at the moment i've been experimenting with Bi-amping again, so wondering about what your experience is.


If you plugged a series bass into an F2-B and took the individual outputs through a stereo power amp to two cabs one on each channel. "Should" there be any difference in what you "hear" compared to taking the F-2B mono out into the amp set so that one input goes to both cabs.


My thoughts were that the should sound different since one scenario the outputs are combined in the air from the speaker and the mono option the outputs are mixed electrically. In my home the difference just seemed to be the mono was slightly louder.


When I did the same using the IN-2 to do the switching between the pickup signals going to individual cabs then combined to two cabs. The sound was louder and fuller.


Am I right in thinking that this is because the IN-2, A + B setting combines the pickup outputs before sending the same combined signals to each side of the F-2B? hence both the F-2B channels are effectively amplifying the combined mono neck and bridge signal rather than the neck and bridge individually.

[JimmyJ]

Hey Jazzy,

In my opinion there is definitely an audible difference between running full stereo vs summed mono.  When the two signals from the individual pickups are played through separate amps and speakers there is a bit more audio information that is allowed to "combine in the air".  When you sum the two channels to mono there are parts of the signal that naturally cancel because the pickups are reading the string in different areas.

This cancellation is subtle, mostly in the high overtones, and might vary depending on what note you're fingering.  Think about playing the high harmonic on your G-string located just above the 3rd fret.  That divides the string into 6 parts (and I can't remember what pitch sounds).  That overtone will almost exclusively be heard by the bridge pickup because the neck pickup is close to the "node" our non-moving part of the string.  So in mono that note would not speak as loudly as it would in stereo.

That's a crude explanation but hopefully you understand what I mean.  Even higher overtones might be seen by the pickups completely out of phase and would cancel each other when summed to mono.  In stereo, at least one channel would attempt to pass those high signals to the speakers.

Again, we're talking subtleties here and really only in those higher overtones.  Stepping 10-feet away from a stereo rig might negate these differences.

Jimmy J

PS: The term "bi-amping" usually means splitting the audio frequencies with a crossover and running highs and lows through different amps and speakers.  That's normally done at higher volume levels so the amps and speakers are not sharing frequencies and can concentrate on their portion of the sound (think sub-woofer).  What I think you're asking about is "stereo" vs "mono", right?

[lbpesq]

I essentially use a hybrid of this system for guitar.   I plug my guitar into channel A, then jumper the second A input to channel B.   I then tweak channel A to accentuate the highs and channel B to accentuate the lows.   The F2-B goes through a stereo power amp (Carvin DCM00L), with channel A going to a 1x12 loaded with a stock JBL K120.   Channel B goes to a 1x12 loaded with a K120 with a hemp cone that sounds a little darker.  I then tweak the relative volumes of the two channels to get the tone I want.  Works quite well.  (But just bringing along my Quilter is a lot more convenient.)

Bill, tgo

[BeenDown139]

In my opinion there is definitely an audible difference between running full stereo vs summed mono.  When the two signals from the individual pickups are played through separate amps and speakers there is a bit more audio information that is allowed to "combine in the air". 

FWIW my SII is stereo only but my A-bass (shop night fretless with anneversary electronics) has a mono/stereo switch on it.  my bass rigs can both be configured to be either full stero or bi-amped to accomidate these instruments along with my mono basses.   there is a definite loss of (percieved) clarity going from stereo to mono on the A-bass. it goes from being a fretless stereo tone monster to a rather blasé sounding nice looking piece of woodwork in mono.  i can't try it with the SII without re-wiring my rigs, but after hearing the difference it makes on the fretless, i'm not particularly motivated to try it.
when i play the SII live, i'm stereo on stage and i send a mixed mono signal to the FOH.  it sounds OK out front, but definitely not like it does on stage.  haven't gigged the A-bass yet, trying to find a way to make a 4-string fit into my mostly 5-string sets.

hth

t

[JimmyJ]

I only ever used true stereo in a couple special recording situations.  Meaning we recorded two tracks of bass, one for each pickup output through matching DI boxes.  When mixing we only panned the two tracks slightly off center with the bridge pickup providing most of the sound.  Something like "10 o'clock" on the bass pickup and "1 o'clock" on the bridge.  The result when listening simply sounded like mono centered bass but if you listened very closely there was a slight stereo image and overtones would shift a bit from left to right.

It was a subtle effect and only appropriate for special projects where they didn't mind if the bass took up a LOT of bandwidth.  It's a great big sound!

Bill tgo, you're simulating true bi-amping the way you're running your rig.  Just without a high-pass/low-pass crossover.  I bet that sounds great.

Jimmy J

[jazzyvee]

Jimmy J

PS: The term "bi-amping" usually means splitting the audio frequencies with a crossover and running highs and lows through different amps and speakers.  That's normally done at higher volume levels so the amps and speakers are not sharing frequencies and can concentrate on their portion of the sound (think sub-woofer).  What I think you're asking about is "stereo" vs "mono", right?

I think from your description, yes i'm talking about stereo. So it seems for true bi-amping with my F-2B, SF-2 and In-2, i should set the in-2 for A+B, which i think sends the same mono bass signal to both f2b channels, then use the f2b tone and sf-2 for each channel to eq low and high to send to separate cabs.

[edwardofhuncote]

I'm probably not doing it right.


From a DS-5R with the switch set to Stereo>

Bass output to F-2B Ch1 input
Treble output to F-2B Ch2 input

F-2B output A to SF-2 input A
F-2B output B to SF-2 input B

SF-2 output A to power amp Ch1 (blue for bass or neck)
SF-2 output B to power amp Ch2 (red for treble or bridge)

The left bank of speakers connected to Ch1 contains a big boxed B15 Avatar loaded with a LF Eminence speaker, and an Avatar 112 on top of it with the crossover bypassed to the high frequency horn. This is essentially the "bass pickup" side, though it'd be just fine as a stand alone stack.

The right bank connected to Ch2 is a mirrored pair of Avatar SB 112's. In addition to the 12" LF drivers, they have 6" high frequency speakers instead of horns and adjustable crossovers. Again, this is what the bridge pickup is assigned to, but sounds just fine by itself.


None of that matters if I play another bass through the Living Room Wall of Sound... still sounds great in mono*.


*not that it's pertinent to Jazzy's thread here, but when I want to use the Big Rig here for say, my Custom fretless, and get the advantage of allllll those speakers but not in true stereo, I use a stereo chorus effect pedal that has one input and two outputs. (MXR M134 if you're curious) I send a blue wire to Ch1 of the F-2B and a red wire to Ch2. When I use this effect with the Series bass, it's only used on Ch2, the bridge, looped-in between the DS-5R treble out, and the F-2B Ch2 input. (hat-tip KR)


**YOU GUYS DID THIS TO MEEEE!!!🤪🤣

[JimmyJ]

Ain't no right or wrong way.  Whatever sounds good to you is the way to go. 

Back in the day I had a stereo rig with 2 EV 15" Thiele cabs for the neck pickup and 2x EV 12" Thiele cabs for the bridge.  PLUS a stereo tapped delay which would take only the bridge pickup signal and send the stereo chorus outputs to both channels. It was an inspiring sounding rig!

Having all these options is part of the joy of playing Alembics!

Jimmy J

[rv_bass]

“ Having all these options is part of the joy of playing Alembics!”

Yes indeed!

[jazzyvee]

Jimmy, I know you still have a bass rig for some gigs, but what made you drop all that and just mainly go direct instead of using a bass rig?

[JimmyJ]

Hey Jazzy,

Well, I've found that the opportunities to use all that bandwidth and make a giant sound are somewhat limited in real life.    When I had the stereo rig described above (2x15" plus 2x12") I was mostly playing small clubs with guitar trios - guitar, bass and drums.  That setting is so open that we have extra audio space to fill up. 

In 1990 I had an even crazier tri-amped stereo rig.  Two Meyer Sound UPA-1A with a USW-1 sub cabinet with the related active processors and powered by 3 Crown MA1200 power amps.  (Eventually I closed the ports on the sub cab and used a BagEnd Elf processor - another Ron Wickersham invention if I'm not mistaken.) This rig had an AMAZING, huge, full-range, super-clean sound which was a blast to stand in front of. 

But ...  I brought that rig out on the road when I first joined JT's band and quickly realized I was the only person in the building enjoying it.  FOH was getting the usual mono summed signal.  When I stepped 8-feet away from my amp I would hear the great sound of my bass through the PA (the BIG amp).  Not to mention, the bass sounded just great through the ShowCo (now Clair Brothers) full-range monitor wedges.  I started to feel silly having the crew haul all that kit around just for me to enjoy. 

If I remember correctly, I soon went with two wedges, one behind me acting as an amp and one in front of me acting as a monitor.  Shortly after that most of us switched to IEMs and haven't looked back.

My little Walter Woods club rig does not have a stereo power amp section but it does take the neck p/u into channel-1 and the bridge p/u into channel-2.  I had to build a "tap" to run my 5-pin cable through to get a summed mono output while still allowing the stereo signal pass through to the WW amp. 

Fun with gear!!

So I have found that opportunities to run in true stereo are few and far between.  I'll also add that having a home practice rig that sounds unbelievably amazing can be dangerous because when you get to the gig or the studio you may find the sound uninspiring.   

All that said, it sure is fun to make the extra-large sound when given the chance!

Cheers,
Jimmy J

[jazzyvee]

👍🏾