Planar Speaker Asylum

Welcome! Need support, you got it. Or share your ideas and experiences.

Use this form to submit comments directly to the Asylum moderators for this forum. We're particularly interested in truly outstanding posts that might be added to our FAQs.
You may also use this form to provide feedback or to call attention to messages that may be in violation of our content rules.

You must login to use this feature.

Inmate Login

By default, logging in will set a session cookie that disappears when you close your browser. Clicking on the 'Remember my Moniker & Password' below will cause a permanent 'Login Cookie' to be set.

Moniker/Username: The Name that you picked or by default, your email. Forgot Moniker?	Examples "Rapper", "Bob W", "joe@aol.com".
Password:	Forgot Password?
	Remember my Moniker & Password ( What's this?)

If you don't have an Asylum Account, you can create one by clicking Here.

Our privacy policy can be reviewed by clicking Here.

Inmate Comments

From:
Your Email:
Subject:

Message Comments

Original Message

RE: Progress report: Tympani IVa midrange driver problem

Posted by mikebarney on April 11, 2021 at 12:44:59:

Progress Report: I've confirmed that reducing the bow of the midrange back panel clearly increases the output, so thats the problem that needs to be solved.
Methodology: I built a stand to hold the driver vertically, and measured the frequency response with the driver free-standing (and the back bowed out as I received it). I then clamped a couple of aluminum bars across the back, touching the middle of the back plate, but spaced out about 1/8" on each side, which reduced the bow a small amount, but did not bring it flat, so it still has some bow.
As you'll see in the attached FR graph, the output level increases significantly with just a small reduction in the bow (shown in blue).
These graphs were made with no baffle, and with a patch cord approximation of the original crossover, so don't draw any conclusions from the absolute frequency response, just the relative measurements. And those measurements confirm what I and several contributors here thought: the output level problem is a function of the bow in the backplate, which is significantly greater in this midrange than my other channel.
Next Steps: I've designed a mechanism to route the MDF panel to mount a number of crossbars as well as clamps to held the driver in place in the MDF baffle. Once that's done, I can adjust both the number of crossbars and the tension on the crossbars to match the output level of my other channel before buttoning it back up. That will take a week or so...
Mike
PS: I was checking the woofer panels for bowing, and noticed they in fact have metal cross bars, very similar to what I plan to use on the midrange, to keep those wide panels flat.