Sliding Door Side Port, CBOM Makers?

[Derek Blackwell]

Hi, can anyone recommend a maker who offers a side port with a sliding door to adjust this? I'm seeking a shorter scale Octave Mandolin.

In gratitude,
Derek

[Graham McDonald]

John Monteleone does such things 8-)

[amowry]

I would guess most makers would do it if asked

[Jeff Mando]

A vintage trap door Gibson banjo comes to mind......

[Derek Blackwell]

I would guess most makers would do it if asked

Thanks, but I doubt that very much. I'm looking for a sliding door on the side port, not the top, so this would be curved, and an intricate piece of work. The main reason I want this is for a purely acoustic method of hearing my own instrument better, when desired, but it would also change the overall tone somewhat, and the way the instrument projects from the top. As much as I like expensive science experiments, I'd feel a lot better about asking someone who's done this before.

[amowry]

I've done it, and it's not as difficult as you might think. It helps to position the door on an area of the side that has a relatively consistent curve, so the door matches the side curvature when open as well as when closed. It slides on two curved tracks lined with felt.

Side ports don't change the overall tone or projection nearly as much as you would expect based on the area of the opening. In fact, listeners in front of the instrument typically can't hear any difference with the door open or closed. Covering up a soundhole on top of the instrument lowers the main air resonance noticeably, but covering up a side port doesn't affect it nearly as much. It's usually only the player who can hear any difference, so the main purpose of the port is to act as a "monitor" for the player.

[Derek Blackwell]

Thanks so much Andrew. Yes, an acoustic method of monitoring is the main thing I'm after, but I'd like to be able to adjust it.

[dhergert]

I have one on my Alcoa double bass, in the driver-side C. Mine is a hinged trap door. The port was primarily put there for inside setup and repair access, but I do use it for monitoring, often, in primarily acoustic situations.

To help manage your expectations, it's worth mentioning that tone and volume coming out of a side port on an instrument may not be exactly the same tone and volume that the audience hears coming out of the front of the instrument. On my double bass, the tone and volume from the side port is a lot more hollow and boomy than the tone that comes from the front of the instrument, and I'd expect that to be a similar situation, scaled down for a guitar or mandolin.

I've also done tone and volume experiments on a 1923 Gibson trap-door mandolin banjo that I used to own, and I found the same thing.

So if your goal is to specifically judge and perhaps adjust the tone and volume of the instrument based on what you hear coming out of the side port, you may find that the audience hears something different than you do. On the other hand, if the side port is simply to facilitate allowing you to hear yourself play over other instruments, it should help at least a little.

And, side ports are wonderful regarding being able to see, setup and maintain the inside of your instrument. A number of us in the double bass community are sold on them; if I were ordering a new double bass, I'd order it with one.

[amowry]

Makes it easier to get the cats out of your mandolin too.

[Phil Goodson]

Mario Proulx (Canada) made some of those some years ago. I haven't seen him post in quite a while. Don't know if he's building or not.

http://www.proulxguitars.com/mandolins.htm

Here's one with side port.

[allenhopkins]

I posted on your other thread in the CBOM forum, suggested talking to Bernie Lehmann here in Rochester.

[amowry]

Because the port is a relatively minor component of the instrument as a whole, I'd suggest playing as many different octaves as you can to find the one that you prefer, and then approach that maker about building one with the port.