Tonewoodamp

[DrAlx]

Saw this video for the "tonewoodamp".  Concept (and result) is pretty cool, and a lot of fingerstyle guitarists have said good things about it.

https://www.youtube.com/watch?v=C3pyDeLTL48

The DSP/FX bit isn't the interesting bit for me.  I am more wondering about what sort of driver was used for the guitar body.  I suspect the driver needs the 4 strong mount points surrounding it in order to vibrate the body without sounding too tinny.  Has anyone here had a look at one of these?

[iainpunk]

Search "dayton audio exciter"

I have build a speaker cab with this technique! Using aluminium sheet metal as speaker. It sounds verry tinny indeed, but it really depends on the material used, big cardboard boxes work the best, loud and clear tones!

[Mark Hammer]

"Exciters" have been around for 50 years if not more.  I recall many ads showing how you could turn this or that into a speaker.  They are also the basis of plate reverb, where a transducer is attached to a big suspended piece of thin sheet metal, and a contact mic of some form senses the continuing vibrations of the sheet.

I would imagine that the humorous part of the demo video - being the sense that the reverb is coming from behind the guitar - stems from the back projecting like a rear-facing speaker.  The sound may come out of the soundhole, but it is the back, not the top that is being vibrated.  I would also imagine that the potential for audible reverb depends on the stiffness, bracing, and shape of the back.  Some designs are going to focus on a stiff non-resonant back, and others will allow the whole instrument to vibrate.  Neither of those is inherently good or bad, just a different strategy.

I don't know how the Tonewood affixes to the back of the guitar, but it appears to be something one doesn't adhere to the back in a semi-permanent way.  Many of the exciter drivers - at least the smaller ones - will have an adhesive "cap" at the top of the driving cone, that assumes you're going to stick it to a specific surface and leave it there.

The good news is that reverb rarely assumes full bandwidth.  So if the driver and guitar back can't do anything better than 1khz, that won't detract from a pleasing reverb.

[DrAlx]

Thanks for the info.  Most useful.

The semi-permanent attachment is magnetic.  There are 4 adhesive pads stuck to the inside of the guitar.  Either those pads have strong magnets on them, or they have disc of metal on them and the amp box has the strong magnets. I believe the tonewoodamp was a kickstarter project and I wouldn't be surprised if it started off by just gluing an audio exciter to a guitar and hooking it up to an FX box. 

Some of those dayton exciters come with 4 adhesive anchor points built into them to give the larger base response.
I have an old beater guitar with a pair of DIY piezos glued under the bridge for stereo output, and I think adding an exiciter to it (probably internal) will be my next project when I can find the time.

[Mark Hammer]

Your description of the way the unit attaches to the back of the guitar makes sense, given how quickly and easily the demonstrator was able to affix it in the video.

I picked up a quartet of small 3W exciters when I dropped by Parts Express on my way to Summer NAMM.  My intent was to use them for a DIY spring and possibly plate reverb.  Once I get on that project, I'll be sure to report back.

[caspercody]

Hello

I really like this idea of trying the Dayton Audio Exciter on the back of my acoustic, driving it with a small wattage Class D amp, and using my existing pedals for modulation. But what is the best Dayton Audio Exciter to use?

I found these (2) on Amazon:

http://www.daytonaudio.com/specs/specsheet_e.php?prod=295-218

http://www.daytonaudio.com/specs/specsheet_e.php?prod=295-220

Which one would be best to use for this application??

Anyone know of a good 5W Class D amplifier?

Also check out what this guy did:

https://crabfuartworks.blogspot.com/2017/09/play-acoustic-and-electric-guitars.html

Thanks
Rob

[DrAlx]

Gonna try same experiment.

Ordered a DAEX19SL-4 on eBay, and a small class D amp. Search for

PAM8403-5V-2-Channel-USB-Power-Audio-Amplifier-Board-3Wx2W.s

Not sure how badly it will feedback as I have piezo. Ideally need wet FX with no dry. The tonewoodamp has a tunable notch filter.

[Mark Hammer]

I wouldn't worry too much about the bandwidth or distortion specs of the particular exciter.  The guitar back is not exactly going to transform into the world's greatest loudspeaker.  More critical will be the placement of the exciter, and the quality of the physical contact.

Ironically, I have one of the little bullet-shaped exciter modules shown in the video, albeit manufactured under another name.

[caspercody]

I go the DAEX19CT-4 today, hooked it up to a Velleman 8066, 3 watt amp I had lying around.

I plugged guitar in, cable down to TC Electronics Flashback and Hall of Fame, cable up to Velleman amp and into exciter.

It works!

Moved exciter around to hear different sounds, and in most areas I get feed back when I turned up the guitar volume. I do not know if the Toneamp gets a lot of feed back?

Thinking of getting a 1590LB metal enclosure and mount exciter in it with a 1/4" jack. Then putting a strong magnet inside guitar, and this would hold the 1590LB metal box in place. There would be (2) guitar cables from guitar down to pedals and amp on the floor.

Any thoughts on feed back, maybe a pot on the amp? Any better ideas of enclosure or holding to guitar?

[deadastronaut]

cool, so you could add belton reverb brick to your setup instead of pedal, and have it coming from guitar?.

if so thats very cool...

[DrAlx]

I read the HOF has a dip switch to kill the dry signal. Did you send just reverb with no dry to the exciter?

[caspercody]

I did not do anything with DIP switch, did not know there is one.

Now I am curious about that will need to open pedal and take a look

[Mark Hammer]

In 1966 or so, before I got my first electric, I discovered fuzz on my $25 Regent acoustic, by taping a nickel (Canadian of course) to the lower bout of the guitar, just a bit and behind the bridge.  The nickel was essentially loosely hanging off the guitar, so that it could vibrate against the top in sympathy with power chords, if I hit the strings hard enough.  To my young AM-radio-inspired ears, it sounded just like the radio.  Of course, it didn't, but you would have been hard-pressed to persuade me otherwise.

I mention it to note that lots of things can be achieved by vibrating the guitar back or top in strategic ways.  Reverb and echo are certainly first-tier things to aim for, but one needn't restrict oneself to those.

[DrAlx]

Got the exciter and class-D amp I mentioned up the thread. Taped the exciter to the back of my guitar, and have been experimenting. I have a BOSS BR-600 multitrack recorder and I have been using its FX loop. I have a piezo glued under the bridge and I found it hard to drive the exciter at loud volume without also getting feedback. I finally found one way which killed the feedback and let me crank up the reverb nice and loud and it worked really well.
The chain is basically this with just 2 effects in the BR600.

Piezo ---> 100% wet pitch shift set to Detune ---> 100% wet hall reverb ---> Class D amp ---> Exciter

Sounds real good. I know the tonewoodamp has 2 tunable notch filters to kill feedback but the de-tune does the same thing automatically. The problem I now have is that I was planning to build a simple reverb using the Spin FV1 and using that instead of the BR600, but then I will be missing the pitch shift required to kill the feedback  
I know chorus can give a varying pitch shift but when I tried using it instead of detune there was feedback, and I am not sure if that was down to the wet/dry mix of the chorus. Was wondering if anyone here has ever programmed a pitch shift on the FV1?

[caspercody]

Anybody know a good notch filter pedal that could help with the feedback issue? I have it also when I put the exciter on the back of the guitar.

[DrAlx]

I also tried a single coil pickup instead of the piezo, and wet reverb on its own worked OK and didn't need any detune to prevent feedback.   I prefer the sound with the piezo though because body knocks get the reverb effect too.

[Fabeii]

Anybody know a good notch filter pedal that could help with the feedback issue? I have it also when I put the exciter on the back of the guitar.

You actually need 2 resistors and 2 caps to make a Notched filter so it's not that hard to find something to work around. You just need to find the right spot!

Two good reads:

http://www.muzique.com/lab/notch.htm

http://geofex.com/Article_Folders/EQs/paramet.htm

[caspercody]

Thanks!!

I guess the big question is what frequency's would work to filter out the feed back?

[caspercody]

Is a equalizer a adjustable notch filter?

Would the Sonic Stomp be a good notch filter?

[caspercody]

https://support.tonewoodamp.com/support/solutions/articles/17000024241-notch-filters-video-

Here is a good video on their notch filter adjustments. Seems like a lot going on here, maybe digital?