Acoustic Presets using dual-source PU system

[paulasbell]

I've been using my AxeFx2 with my K&K Trinity dual-source system for years, (along w/ 2 other guitars) for solo acoustic gigs. I've been running a stereo 1/4" cord from guitar to K&K blender preamp, then the "mix out" to Rear Input 1R. (Front Input is for the other 2 guitars). Then, I've been putting a Vol/Pan block at beginning of each preset, panned either full L or R, so when I change the preset, it changes which guitar is active. It's been working great.

However, I've always suspected that I could split the mic and PU signals, out of the blender, input them into the AxeFx, and treat them separately. (Obviously, it would be helpful to have different comp settings, TubePreamp settings, ParaEQ settings, etc, for each source, before mixing them together and hitting the delay and reverb blocks).

But i wasn’t sure how to do it. Just figured it out.

The PU-only signal goes to Rear Input 1R, as before. But the mic signal now goes to Rear Input 2L. I put an FX Block first, in a separate row, and added Tube Pre, Comp, ParaEQ, before joining rows using a Mixer block. Works great, and resultant tones are noticeably better than previous method. Love it!

I’ve got an idea for the next experiment… but maybe some savvier folks can tell me if it’s worth trying.

I’d love to be able to dispense with the K&K Blender-preamp entirely, get a stereo-to 2 monos 1/4” splitter adaptor, and pipe the signals into the AxeFx rear inputs directly. I suspect that MIGHT work for the PU signal… however, I’m suspecting there might not be enough gain within the AxeFx to deal with a mic-level signal.

Can anyone verify that, one way or the other? Or, any suggestions about a better way to accomplish what I’m trying to do?

 

[krcassid]

I've been using my AxeFx2 with my K&K Trinity dual-source system for years, (along w/ 2 other guitars) for solo acoustic gigs. I've been running a stereo 1/4" cord from guitar to K&K blender preamp, then the "mix out" to Rear Input 1R. (Front Input is for the other 2 guitars). Then, I've been putting a Vol/Pan block at beginning of each preset, panned either full L or R, so when I change the preset, it changes which guitar is active. It's been working great.

However, I've always suspected that I could split the mic and PU signals, out of the blender, input them into the AxeFx, and treat them separately. (Obviously, it would be helpful to have different comp settings, TubePreamp settings, ParaEQ settings, etc, for each source, before mixing them together and hitting the delay and reverb blocks).

But i wasn’t sure how to do it. Just figured it out.

The PU-only signal goes to Rear Input 1R, as before. But the mic signal now goes to Rear Input 2L. I put an FX Block first, in a separate row, and added Tube Pre, Comp, ParaEQ, before joining rows using a Mixer block. Works great, and resultant tones are noticeably better than previous method. Love it!

I’ve got an idea for the next experiment… but maybe some savvier folks can tell me if it’s worth trying.

I’d love to be able to dispense with the K&K Blender-preamp entirely, get a stereo-to 2 monos 1/4” splitter adaptor, and pipe the signals into the AxeFx rear inputs directly. I suspect that MIGHT work for the PU signal… however, I’m suspecting there might not be enough gain within the AxeFx to deal with a mic-level signal.

Can anyone verify that, one way or the other? Or, any suggestions about a better way to accomplish what I’m trying to do?

Hi: I've been using my axe with dual source pickups for years. I have a number of acoustics. My old system was a k&k pure western combined with a Baggs lb6 passive ust. Ive slowly been converting my acoustics to the Trance Audio dual transducer setup and like this system much better. Having run virtually every type of acoustic pup over many years, I can share a few things:

Although I haven't used a Trinity system, I can tell you that all passive acoustic guitar pickups, and I assume the Trinity is Passive since you are using an external pre, require special preamps for both impedance (2-5 Mohm often required) and to provide the massive amount of gain you need to turn that tiny transducer signal into something workable. Many of the older pups (i.e. fishman) had very poor internal preamps. All of mine are passive and I use pretty specialized preamps to match impedance and provide the gain nessecary to connect to a line level device. I suspect you need the the external pre or you will find that the levels going into the back of the Axe will be far too low. Even with preamps, I sometimes have to add 10+ Db of gain in the axe. Skipping the pre is likely to give you subpar sound, poor impedance match and a lot of noise when you try to jack up the signal inside the axe. I use a number of pres designed specifically for this purpose and I suspect they are substantially better than the Trinity pre. I use 2 Raven Labs preamps (From Steve Rabe of SWR). His USIP is excellent if you can find one. I also use a pair of Avalon U5s. The trance system comes with its own external pre which is quite good. Your preamp is critical on an acoustic. My 1st suggestion would be to investigate higher quality preamps.

I go into the fx loop via stereo inputs 2 on the back with each transducer on one side. I typically use a mixer block, a compressor, an eq and a filter block (to add gain if necessary). I get each transducer dialed in separately and then mix them back to mono before efx. I have a preset for each guitar so I can plug and play

Using a non blending pre with a good impedance match will allow you to bring 2 pristine signals into the efx loop with adequate gain in most cases. Bypassing the preamp is unlikely to give you good results but separating the transducer signals is critical. If they are blended, you can't correctly eq them. So, you are on the right track by seperating the 2 and blending in the Axe. I would strongly encourage you to find the best preamp w/ 1 Mohm min impedance. This will give the Axe an optimal signal. My favorites are:

The Raven Labs USIP (universal stereo instrument preamp)
Raven labs PMB1
Avalon u5 (expensive at $1000/pair)
The trance amulet system with external preamp (by far the best acoustic solution I've found)

All of the above will give you an excellent stereo input into the efx loop.

I am not knocking the k&k pre. It may be fine but most of the pres that accompany acoustic guitar transducers are woefully inadequate

One last thing: I wouldn't use the tube pre on an acoustic. Although it is the most colorless amp in the axe, it still has plenty of color and saturation etc, things you don't typically want on an acoustic. If you need more gain, use a flat filter block to add gain inside the axe.

 

[paulasbell]

Thanks for your extensive rundown! Many helpful ideas there… many I was aware of, but the repetition of them was quite useful to me.

I've had more time in the last few days to put into this quest than I've had in years. So, I've tried a number of different angles… some as suggested by you, as well as a few others.

Since I don't own the Raven Labs units mentioned, I started my experiments w/ your suggestion of subbing in Filter blocks, instead of the Tube Pre blocks I had been using previously. (The main reason I initially used the Tube Pre blocks was the far-ranging parameters available within them, apart from simple gain boost. I have wound up tailoring my K&K PU tone extensively using the dynamic parameters… Character, Pick Attack, Dyn Presence, etc.) When I tried using just the Filter block, I was keenly aware of how much less colored it was… even though I use an extremely low gain setting in the Tube Pre block. However, after a fair amount of back-n-forth, I concluded I preferred the tweaks I made in the more colored Tube Pre to the relatively "un-tweakable" Filter Block. OTOH, I preferred the uncolored Filter Block for the mic channel… not surprising, I guess. Thanks for that suggestion!

The last time i was able to devote extensive time to the tone quest, I experimented w/ ToneMatching my K&K setup w/ pro-recorded acoustic tones from several of my own CD's. I initially assumed that that should yield useful results, but never came up with any matches that were helpful. (In retrospect, I'm not confident that I was inputting my ref signal correctly). This time, however, I came up with a few TM's which helped a great deal. I'm now using one of them, in a 50% mix, which has almost entirely eliminated the somewhat boxy, "cardboard-like" artifacts of the transducer sound. Based on my experiments, i'm thinking that more TM experiments is where I'll put my next efforts.

Anyway… many thanks for your comments, and advice!

 

[krcassid]

Excellent! The one thing I forgot to say: there are no right answers. Every guitar is different. It really has more to do with the signal being produced by the transducers. I have about a dozen acoustics, Each one requires a different solution. That's the beauty of the Axe. I can get them dialed in and saved. When/ if you have a chance, do try one of the higher-end preamps. I think you will be pretty surprised how much of a difference they can make. IE: open up the case on a K&K or a Fishman and look at the components in there. It's very rudimentary. Then, go open up an Avalon U5 (darn thing weighs 20#!). IMO, the 2 things that matter most are:

1.) the placement of your transducers. It is critical that this be done well & right. Even though I have excellent techs, there are some we've had to redo several times. It is astounding what a difference 1/16th" can make in the placement of those transducers under the bridge.

2.) The quality of your preamp (If you watch Ebay, the Raven USIPs come up now and then)

The Axe will do a fantastic job if you nail the 2 pieces above. But, I still have guitars I am not happy with. These are georgious hand-made instruments that sound amazing on their own (Goodalls, Collings, Santa Cruz...) But, it can take a lot of work to get the transducers dialed in.

I can't say enough about the Trance Amulet system. I really think it kills all my other setups. It is similar to K&K but the transducers are larger & much more detailed. It gives you a balanced stereo out through a mini XLR jack in the end pin. The guy at Trance (Gary IIRC) is very good in terms of support. Your 1st install is expensive (about $600 for Transducers and preamp). But, one you get the pre, additional sets of Transducers for other guitars are $3-400.

The guys at Gryphon Guitars in N. CA work with Trance and will do a great job installing the system if you are wiling to ship your guitar. Most local techs do not know the Trance system. However, my 65 Martin D35 still has a K&K Pure Western/ Baggs LB6 in it and it sounds killer thru the Axe.

http://www.tranceaudio.com/

 

[paulasbell]

Thanks again, for the time you've taken to make such a detailed reply!

I should have mentioned earlier that I'm quite familiar w/ the Avalons, as I often use them, or my own Millennia TD-1, when I've tracked in the studio… for my own CD's, as well as plenty of others. Excellent units, for sure… but i'm forced to consider what I can realistically fly with, for gigs. That, of course, is where the smaller preamps become essential.

Speaking of flying.. I'm heading to Cali in Jan, where (among other things) I'll be teaching several workshops at Gryphon. I know Frank, Richard J, Michi, and several others there from way back. So I'm now considering using that opportunity to get up close and personal w/ the Amulet system. Thanks for putting that bug in my ear!

 

[krcassid]

Sounds like you've got it down! It would definitely be worth a call to Gryphon to see if they have a Trance equipped guitar around. Or, even better, take a side trip (with your guitar) to Trance in Grass Valley and check them out. I'm not sure that Gryphon keeps them in stock or that they'd have a guitar fitted with a Trance. But, the Trance inventor (IIRC, Gary), was super-helpful to me.

If size is important, you definitely don't want to lug around U5s (you'd need 2). Raven's USIP is not a ton better (1.5 rack space unit). But, Raven's smaller PMB 1 might be a step up from what you have and it's small. Trance's Pre is about the same size. But, unlike the Ravens, it is strictly a pre. It has no EQ or other features but you have these in the Axe in spades so they are unnecessary. The Trance pre is true stereo and I like it quite a bit. It was the only PUP that did my Koa Goodall Baritone justice.

BTW, one thing that I'm toying with is the use of multi-band compressors in the Axe on acoustics. I think that, if could figure this out correctly, it would work better than the standard compressors. So far, it's just an experiment but I think it's worth looking at. In the studio, I use a pair of EL8 Distressors