Thanks for visiting.  I think you'll find this site very interesting.
                  Frank Geiger


Customer Comments

R.S. called from Michigan to say that the Tone Amp "worked great" on his aluminum rim banjo, and that he got the best sound with the tone amp attached to the coordinator rod, not to the aluminum rim.

H.L. wrote the following from Germany:  Hi Frank...The volume of my B&D Siverbell No.3 increased and got more punch and definition at the mid- and high range. Furthermore the notes seem to ring more fully.  In other words, this Tone Amp of yours was a good investment.

B.B. wrote the following from New Mexico after installing his first one, then ordered three more:
“The banjo plays great and sounds quite good since the renovation but it does have less volume than two other Mastertones I have.  With the Tone  Amplifier added it has distinctly more volume and tonal richness up and down the neck.”

Jim Riley, noted Jazz Band Tenor Banjoist & Professional in Raleigh, N. C. wrote:    Just wanted you to know that I tested your tone amplifier at two gigs on Saturday, and was completely satisfied with the results.  I again asked the other band members for their opinions, regarding how my banjo sounded, and received their approval.  This time they unanimously confirmed that my banjo  sound was noticeably bright and clear.  

I sent customer H.L. in Germany one of the new "Blaster" tone amps in a "Travel Caddy" and asked for his comments.  This is his reply:  "Hi Frank, I am very pleased with the new power tone amp. It's indeed more powerful, and with my B&D SiverBell all frequencies seem to be more strong.... For Irish Music/Sessions it's really grand. - I think  your "Tone Amp Travel Caddy" is a very useful tool and it works well. Thanks a lot. All the best..." Australia wrote the following after using it in his B&D Silverbell tenor: The extra volume of sound is amazing with a nice prolonged ring added to my Banjo, and it can be used for other stringed instruments.

From K-E-W in Chicago who wrote the following after implementing the bending modification to his Tone Amp:  "Hi Frank,  I implemented your last suggestion to bend the tone devise, and I have to admit. I  think my banjo is now too loud for my little apartment.   I LOVE IT!"

G.B. in North Carolina wrote the following after installing the Tone Amp in his Clawhammer Banjo made from a pre-war Bacon and Day tenor pot without tone ring which he plays with the resonator off:  "Frank...I received the stick-on tone amp for my banjo.  I can't believe how well it works!!  No tone ring but now sounds like there is!"  

New Customer Posting on "":  Just attached my tone amp.....greatly improved the sound level and quality.  I am now a believer!

Comment rom N.L. in France:  “Simply amazing how it can improve the timbre of the instrument. With a metal part it was good. But I added the 2 others and I heard more harmonics.  Belle invention, Frank!”

Comment on new Butterfly Amp in his Bacon Banjo from Tone Amp Customer in Germany:  "Hi Frank, The 'Butterfly Timbre Amp' makes the sound of the E- and A-string of my Bacon Day Shortneck more crisp. The sustain improved , but is not too long for Irish Music. Overall I now like the sound of my B&D even more.  

Thursday, September 7, 2017 @8:53:00 AM  "FOLD THE TONE AMP FOR THE BEST SOUND"  

I have no idea why, but a little over a week ago it occurred to me that the design of my "Geiger Movable Tone Amp For All Banjos" enables the tone amp to be greatly improved simply by bending it along two bend lines.  This is because the tone amp has three separate audible sound outputs - low frequencies on its left, high frequencies in its center, and harmonic frequencies on the right.  This happy and undeserved thought meant the outer two outputs of audible sound from the tone amp could be "aimed" at the center output to cause all of them to intersect and be amplified.  Amplification would occur because sound waves in air, just like sound surface waves on surfaces, which have the same or similar frequencies and meet coming from from different directions, will amplify when they meet.  This well known principle of physics, called "constructive inteference", is why music sounds so beautiful in a concert hall, and why everyone thinks that they sound great singing in a shower! (Because they actually do!)

So I did some experimenting to determine how much to bend the left and right sound output planes on my tone amp to get the best sound from my Gibson Mastertone tenor banjo.  I got the best sound with the left low frequency plane (the one with the two amplifying staples) bent up 90-degrees, and with the right sound output plane (the one with the steel tone piece and "harmonic loudspeaker") bent up 30-degrees.  When I finished this bending experiment the lows from my banjo were incredibly rich and loud (much more than  before this bending) and the highs were crystal clear and ringing with nice sustain.  I wondered why I hadn't thought of this simple improvement before, since everyone knows that beautiful sound is 3-D, not 2-D!  Why in the world did I even design a 2-D tone amp in the first place?  Duh?  (No, ...Duuummmb.)

So, I added two bend lines to the tone amp where I had made the bends and revised the instructions recommending how to use them.  I also eliminated the "Blaster" model because the bending gave much better volume without sacrificing quality in the high tones which one customer had noticed who had used both the "Blaster" and "Original" models.  You can see the bend lines on page 3 of the "Theory and Directions..." document if you download it from the "Ideas" page of this website.  Thanks for checking my blog.  

Frank Geiger

Monday, October 9, 2017  @1:10 PM.  "Improved Volume and Sound Quality Obtained From New Placement Of Heavy Clear Tape".  (No action is necessary on your part.)  

On October 6, 2017 I decided to move the bottom edge of the heavy clear tape that covers the cross a bit lower on the tone amp from its present position which was at the bottom of the bottom leg of the cross.  The reason for this was because the tone amp was bending forward or backward at this narrow location  (which was only 1/2-inch wide) and the tape was offering no resistance to this bending because it occurred just below the tape's bottom edge.  Extending the tape lower on the tone amp would strengthen this narrow area and should stop the bending.  So the question was where to put the new bottom edge of the tape for the best sound from the banjo.

When I looked at the tone amp the solution seemed obvious.  Because weeks earlier I had added two vertical bend lines below and to the left and right of the location where the tone amp was bending.  The purpose of the bend lines was to allow the player to "aim" the audible sounds produced by the left and right audible sound emitters to get the best combination of volume and sound quality from the banjo when their outputs intersected in air.

If you have been following our postings about sound surface waves you might recall reading that our experiments suggest that sound surface waves travel efficiently in the adhesive layer of this heavy clear tape, so I decided to extend the tape to just inside where each of the two bend lines intersects the top edge of the tone amp.  This placement would allow the sound surface waves from the adhesive layer to move directly onto the tone amp top edges of the two movable audible sound output planes on the left and right of the tone amp.  This was desirable because sound surface waves travel efficiently and with large amplitudes along edges of surfaces.

I made these changes and then played my banjo and immediately noticed improved volume and sound quality from my banjo.  The problem area with the bending also seemed stronger and less likely to bend.  A decision was made to use this new placement of the heavy tape on all future tone amps.

Monday, October 9, 2017  @2:10 PM.  "Amazing Volume and Sound Quality Achieved From New Tone Amp Placement In The Banjo"   ATTENTION TONE AMP  CUSTOMERS:  MAKE THIS EASY CHANGE FOR AMAZING (AND FREE) IMPROVEMENT IN SOUND QUALITY AND VOLUME FROM YOUR TONE AMP!

​Two days ago I changed the placement of the tone amp in my banjo from having its tape being in-line with a circumference of the wood rim to being at an angle of approximately 45-degrees to any circumference, and with the free end of the tape at the "bottom" of the wood rim (away from the tone ring) as shown in the photo below.  When I played the banjo I was totally amazed with all aspects of the beautiful sound from the banjo, which I had never experienced before from this or any other banjo.  A likely explanation for this improvement seemed immediately obvious and is explained below.  Frankly, I am embarassed that I had not thought of this before!  

When the tone amp's tape is placed at an angle as shown in the photo, sound surface waves on the wood rim, which are traveling in-line with a circumference of the wood rim, first enter the the adhesive layer of the tape at a 45-degree angle.  Then they are immediately reflected from all edges of the tape and quickly allign with the direction of the tape. An instant later sound surface waves following this first group of surface waves enter the tape and meet with the first group at an angle.  This meeting of waves of similar frequencies coming from different directions at an angle causes them to amplify from the physics principle of "constructive interference".  The amplification of their harmonic frequencies improves sound quality and the amplification of all the waves improves sound volume.  These amplified surface waves then enter the tone amp which further amplifies them and converts them into high quality audible sound in the banjo's sound chamber. .
November 8, 2017, Easy Modification To Travel Caddy To Accept Recommended Tone Amp Angled Placement and Bends Along Bend Lines.

This modification couldn't be easier.  Simply cut off the bottom closed edge of the Travel Caddy envelope (about 1/16-inch) with scissors so that only the top edge and rear edge remain closed.  The remaining two closed edges are sufficient to connect the front and rear faces of the Travel Caddy together and keep the Tone Amp snugly against the banjo's rim during travel, while allowing the bent low frequency left side of the Tone Amp to pass through the newly cut off lower edge of the Travel Caddy. (See photo below.)  New orders for Tone Amps include this change to the Travel Caddy so require no modification.

November 29, 2017. Look For This Widely Available Substitute Tape That Works On Our Products To Pickup And Transfer Sound Surface Waves.

The tape that we use on our products to pick up and transfer sound surface waves is 3M Model 600 tape which is a clear acrylic tape.  It works very well and we measured its thickness at .003 Inch.  Unfortunately, this tape only comes in large rolls that require a large roll tape dispenser so is not widely available or economical if you just need a little bit of it.  Fortunately, 3M makes a similar tape that we have used and which, although it is slightly thicker at.004 inch thick, it seems to work well enough with our products.  You can probably find it in inexpensive small rolls at your local office supply store, drug store or other store that sells school supplies.  Be sure NOT to purchase 3M's "Magic Tape" which is sold in similar rolls with green plaid packaging because it won't work on our products.  Instead, look for 3M's "Gloss Finish Transparent Tape 1/2" Wide" in a Red Plaid-decorated dispenser containing 12.5 yards of transparent tape.  It may be attached to a card as shown in the photo below.

​​​​​Dec 1, 2017.  Recently I invented a simple bass amplifier to be used with our "Movable Tone Amp for All Banjos".  

It worked OK but the low tones weren't particularly beautiful.  I solved the problem by adding a high frequency (harmonic) amplifier on top of the Bass Amp so that the outputs of audible sound from each would immediately mix and make the low tones beautifully rich.  The improvement was amazing.  Volume, sustain and sound quality of all frequencies were improved when used with our Tone Amp.  One reason for this improved performance is probably due to the fact that both audible outputs were only about 3/4-inch from the banjo head which probably made the head part of the amplifying system.  I've submitted a provisional patent on it and will be offering them for sale very soon.  They will be very affordable and you are sure to be amazed at the sound of your banjo with one, especially if you already own a Tone Amp.

ADDED JULY 5, 2018.  This morning I improved this bass amplifier with a discovery that I had used to improve my "Tone Amplifier for All Banjos" and (please don't ask me why) I had neglected to use the discovery on this great bass amp and enhancer until 15 minutes ago, and it worked GREAT!  The discovery is to use BOTH the waxed braided nylon cord and the 3M 600 Clear Acrylic Tape (with the cord stuck under the tape) instead of just tape for the surface wave inputs. I bought my cord over the web from a company that sells supplies to necklace makers.  Mine measures .035-inches in diameter.  This combination causes many more surface wave intersections and so more amplifications.  ALL FREQUENCIES ARE AMPLIFIED - (Not just bass notes!)

    ​​​​​​​​​​     On the right is a drawing of the side view of our new Bass and Enhancer Amp.  It will explain how it works to readers of "" who have been following our work with sound surface waves and know that: (1) common steel staples are surface wave amplifiers, and; (2) that diverging air spaces having the same sound surface waves on the diverging planes (on either side of the diverging air space) are loudspeakers.

     You can download the 2-page "Theory and Instructions" document that is shipped with this new amplifier on the "Ideas and Downloads" page.  The download is free.

Added July 5, 2018.   The drawing on the right does not show two improvements made to this "Bass Amp and Sound Enhancer" which are the elimination of the non-sticky plastic tab at the end of the tape (because it absorbed sound surface waves), and the addition of the waxed, braided cord stuck to the middle of the clear acrylic tape (as described in the previous entry).

The Bl​​​og Entry About A "Double A Twisted Cross Tape" Formally Here Has Been Removed

After further testing we learned that the "double twisted cross tape", which was described here, could not be depended upon to consistently deliver quality sound surface waves, so we eliminated the blog entry which described how to make one.

July 6, 2018
   This amazingly simple modification of bending the tape around the braided cord in two places and then pinching the tape bends hard together and to the cord (see drawing on right) GREATLY INCREASES AMPLIFICATION!
Sound quality is also excellent.

  Why this occurs is easy to explain.  Because the same sound surface waves are traveling on the tape and on the fibers of the braided cord, hard pinching the tape to the fibers causes more intersections at an angle between waves of similar frequencies.  This amplifies them by the wave physics principle of "constructive interference".  Two "pinching areas used gave great amplification but more could be added if needed given enough room on the tape.