Impedance Demo: 3 Guitars, 3 Pickups, 5 Impedances

[Cochese]

Originally Posted by guitaniac

I was thinking that 20K ohms to 50K ohms is more typical for a mixer input. I'll have to try and find the manual for my own Mackie mixer. (Things have been "rearranged" since moving.) PS I found some Mackie manuals online. My own mixer's (1202VLZ4) line inputs are listed as "10K ohms or more". For one of the FX series mixers which I checked, the line inputs were listed as 20K ohms.

I was aware that impedance changes with the frequency, but thought that it was customary to use a default frequency (1000 Hz?) for purposes of stating impedance values. In any event, the fact that impedance changes with frequency is why you lose more low end than high end when running to an insufficient input impedance.

Looking at the Fishman Prefix Blender stats just now, I see that they list the output impedances like this

Output Impedance (tip): Less than 3.5 k Ohms (the UST, I presume)
Output Impedance (ring): Less than 6.6 k Ohms

Obviously, if you happen to have 3K ohms impedance looking into 10K ohms impedance you're gonna have some degraded signal (by Rick Turner's rule of thumb, at least).

Fishman's discontinued Ellipse Blender has a listed output impedance of 1K ohm, with a recommended load of 10K ohms and up. That's consistent with Rick turner's rule of thumb.

It does appear that Fishman has discontinued the practice of listing output impedances with some newer products like the Matrix Infinity.

The Mackie's line inputs (I have two here) are 10K same as my Soundcraft and Summit Audio line inputs. Line input impedances need to be higher so multiple devices can be connected to the same source without loading down the input. Mic inputs on the Mackie are 1300 ohms and the Soundcraft is 2K. On my Great River the mic input is 1200 ohms and the Summit is 1500 ohms. Pretty standard for mic use. With Ribbon mics like the Royer you want to go 4 times the impedance. Active mics are a different story. The Great River and Summit do have adjustable impedance.

On a mic when the impedance is lowered you get a slight low end roll off and a slight boost of highs. Sound familiar?

Impedance is usually never a problem with a buffered preamp like Baggs and D-Tar etc. You can always for our purposes go low Z to high Z input. It's running passive pickups like an un-buffered piezo or systems like the K&K or Barbera Soloist or a mag pickup where you will notice the most dramatic difference.

Sometimes I think you need to give the respective manufacturers the benefit of the doubt as to what input impedance is ideal for their product to work as "they" intended. This is not to say that if you plug the K&K into a mixer or a 10Meg input pre like the PADI or Felix and it sounds good you shouldn't use it.

[Yamaha Man]

Last week I made a series of recordings trying to show the effects of the new Baggs Session DI unit. I ended up with a recording that I thought would be usable for me. It may not be sonically perfect, but it's good enough for my needs...Here's the chain I used...

D-35>Lyric pickup>Venue DI/EQ>Session muti-band compressor/saturation> Marshall AS50R Acoustic amp> At2020 mic> Fast Track Interface>Computer>Sonar>Audition>MP3.

Here's the final results...
http://www.soundclick.com/player/sin...&q=hi&newref=1

[guitaniac]

We're getting a little far afield (from the input impedance question) here, Martin Maniac, but with the Lyric> Venue> Session signal chain, I suspect you could do as well (or better) going directly to the recorder. I doubt that miking an amp is necessary, and that the extra gain stages (in the amp) may even be counter-productive.

Albeit, if you were working with a UST signal, the amp might add a little "air" to your sound.

[Yamaha Man]

Originally Posted by guitaniac

We're getting a little far afield (from the input impedance question) here, Martin Maniac, but with the Lyric> Venue> Session signal chain, I suspect you could do as well (or better) going directly to the recorder. I doubt that miking an amp is necessary, and that the extra gain stages (in the amp) may even be counter-productive.

Albeit, if you were working with a UST signal, the amp might add a little "air" to your sound.

Well here in my home studio, the amp sounds fantastic and I was trying to capture that to show off what the Session unit can do. I've tried going directly into the recorder and as Doug points out, it didn't sound that good. If I add a vocal track to this guitar recording, it'll be just fine. Any little nuances will be pushed into the background. Sorry to take this off the main thread topic.

[guitaniac]

Originally Posted by Cochese

Impedance is usually never a problem with a buffered preamp like Baggs and D-Tar etc. You can always for our purposes go low Z to high Z input. It's running passive pickups like an un-buffered piezo or systems like the K&K or Barbera Soloist or a mag pickup where you will notice the most dramatic difference.

I'm thinking that even with an active system, there will be some noticeable effect on the signal when the input impedance isn't high enough to maintain a 10/1 ratio. That Wavelength demo of Doug's definitely sounds thinner going into 10K ohms than going into 1M ohm or 10M ohms.

Its an interesting aside that the input impedance of the Wavelength system's preamp is "in the neighborhood of 100M ohms", according to Rick Turner. That makes the raw Wavelength/Element transducer a pretty atypical transducer. Even the passive B-Band transducer (which also requires an atypically high input impedance) only requires a 50M ohms input impedance for good signal buffering.

[guitaniac]

Originally Posted by Martin Maniac

Well here in my home studio, the amp sounds fantastic and I was trying to capture that to show off what the Session unit can do. I've tried going directly into the recorder and as Doug points out, it didn't sound that good. If I add a vocal track to this guitar recording, it'll be just fine. Any little nuances will be pushed into the background. Sorry to take this off the main thread topic.

I suspect that the Session settings may need to be a little different for direct recording than for live sound. Its possible, though, that the amp shapes the sound in a way which can't be duplicated with just the Venue and the Session. I'm sure that we will find out soon enough, as many folks will no doubt be experimenting to see how the Session can enhance their direct recordings. After all, the Session was created in an effort to duplicate studio tricks which were being used to enhance direct recordings.

[Yamaha Man]

Another good reason I have for using a pickup vrs a mic is that I can run my guitar thru my effects pedal board to add any wanted effects BEFORE recording. Running just a mic into the recorder gives you a dry signal which you have to process later...having the effects already in the signal chain, gives me the option of adjusting them to my liking BEFORE recording them. This is great for practicing or music writing, or experimenting with different effects and their settings before hand.

[SpruceTop]

Originally Posted by philjs

Don't want to sidetrack Doug's superlative work (again) but for those folks (eg. Martin Maniac and guitaniac in this thread) trying to record acoustic direct and who have UAD hardware, I wonder if the new Sound Machine/UAD "Wood Works" plugin would help you out? It's not cheap but if you have the hardware then it might be a working solution...the demos sound quite good, I think.

Phil

It seems from the description in the video that the Sound Machine/UAD plug-in uses a variation of Fishman Aura technology.

[guitaniac]

Originally Posted by SpruceTop

It seems from the description in the video that the Sound Machine/UAD plug-in uses a variation of Fishman Aura technology.

If the Barbera pickup is truly quack free, I would think that its dry, string-oriented sound would make a great "platform" for Aura technology, especially if custom sound images are made.

I've suspected for some time that John Buscarino used some Aura sound imaging to enhance the amplified sound of the Barbera-equipped classical in this vid.

https://youtu.be/9Ph5BwDEky4

The amplified tone, which starts around 5:18 in this vid, is flat-out gorgeous. In addition to that, that box which is sitting on top of his amp head sure looks like an Aura Spectrum DI from the side angle.

The amplified tone of this Barbera-equipped double-top steel-stringer is also pretty remarkable. The amplified demo starts around 8:12 in the vid.
https://youtu.be/gAjRkGQC98E

[SpruceTop]

Originally Posted by guitaniac

If the Barbera pickup is truly quack free, I would think that its dry, string-oriented sound would make a great "platform" for Aura technology, especially if custom sound images are made.

I've suspected for some time that John Buscarino used some Aura sound imaging to enhance the amplified sound of the Barbera-equipped classical in this vid.

https://youtu.be/9Ph5BwDEky4

The amplified tone, which starts around 5:18 in this vid, is flat-out gorgeous. In addition to that, that box which is sitting on top of his amp head sure looks like an Aura Spectrum DI from the side angle.

The amplified tone of this Barbera-equipped double-top steel-stringer is also pretty remarkable. The amplified demo starts around 8:12 in the vid.
https://youtu.be/gAjRkGQC98E

That sure is an Aura Spectrum DI on top of his amp and the amplified fingerstyle tone is gorgeous! Check out the logo on the front of his box and the below image from the Fishman website. The second video of the steel string sounds good BUT although he's using a flatpick, he's picking gently so it really doesn't show us how well the pickup holds up under moderate to heavy playing, especially an alternating bass/chord/melody style.

[guitaniac]

Originally Posted by SpruceTop

That sure is an Aura Spectrum DI on top of his amp and the amplified fingerstyle tone is gorgeous! Check out the logo on the front of his box and the below image from the Fishman website. The second video of the steel string sounds good BUT although he's using a flatpick, he's picking gently so it really doesn't show us how well the pickup holds up under moderate to heavy playing, especially an alternating bass/chord/melody style.

Good catch on the Aura logo, SpruceTop. I was just judging from the sound and the general appearance of the box.

With regard to how he demos the steel-stringer, you're correct that he plays it very gently. I recall one demo (on the Barbera site) of a Barbera-equipped steel-stringer being strummed aggressively, but I'd certainly like to hear more, without and with Aura. As you might imagine, aggressive strumming has been the biggest problem area for me, with respect to recording off a pickup.

[Doug Young]

Martin, the recording thing just depends on what you want. I prefer a natural acoustic sound - that's why I play an acoustic. But everyone has different taste, and if you use effects pedals, etc, then you're in a different space - basically really a hollow body electric guitar of sorts - which is fine. Monte Montgomery, even Phil Keaggy get great sounds with effects, distortion, chorus, loopers, etc.

There are lots of ways to get "usable" recording sounds with a pickup - to me, they just all pale compared to just a mic, but there are techniques that can be acceptable depending on your taste. I did an article for AG years ago, something like "27 ways to record with a pickup" or something. Maybe I'll start a separate thread with some ideas and demos - I've actually learned some more techniques since then, and people can add on whatever they've found that works for them.

[Doug Young]

OK, Gary, mixing our topics here a bit, but here's the strumming example you wanted. Recorded direct, with the Felix set at 1M. I recorded the Barbera followed by the wavelength, 1.2 mm pick, maybe not strummed as hard as you do, but harder than I ever would :-)

[Doug Young]

Here are the direct recorded tracks some people wanted to hear. Same setup, same order, just no amp. I'm running the Felix right into the line in of my Apogee interface. As before the order is channel 1: 1M, 10M, 10k, channel 2, 1M, 20M, 330K

K&K:


Barbera:


Wavelength:

[guitaniac]

Thanks so much, Doug. The Barbera sounds a tad cleaner to me (in the strumming samples), but both recordings are remarkably free of the crispy critters (like the sound of cellophane crinkling) which I get when recording a hard-strummed UST, even the Wavelength UST. (I used a Wavelength system in my Taylor for years.) Perhaps you have a better recording process. I'm sure that you have a more refined touch.

Thanks again, Doug.