I just discovered this site today, thanks to a link posted on the Sound Practices discussion group (joelist) in which I have been a participant for perhaps five years. Perhaps there are some joelist participants here. Anyway, I am a retired EE with audio as a hobby, off and on, for the past 50 years. My interests lie mainly in power amps (tube amps for the past several years, SE and PP, but mainly SE) and speakers. I have bought and sold quite an appreciable number of speakers over the last few years, ranging from TAD HF drivers to Tannoy Golds ((which I used as my primary speakers for some 30 years) to quite a few larger JBLs, Altecs and Peaveys to several of the more rare and exotic full range speakers, on down to whatever. It would take far too long to go into detail.

Anyway, my interest here is learning about the π speaker designs. I perused the various designs and noted something that was somewhat troubling. Perhaps someone can comment further. e.g., the delta 15 states a Qts of something like 1.61, as I recall. It is common knowledge that this to far too high a value to work properly in any kind of conventional enclosure, either sealed, ported, or horn. So, how does the π design differ from other designs with regard to allowing the use of such a high value of Qts. My intuition (and TS simulation) tells me that the bass response of such a speaker should sound entirely wretched. Some of the horn designs look to be little different than a common duct loaded speaker facing into the corner. Anyway, it escapes me how acceptable performance can be expected from a speaker with such a high Qts.

I have a pair of 18 inch peavey speakers that might be suitable for one of these designs. Are the plans available separately? They are currently listed on eBay with no bids, so if they do not sell I would like to explore using them in one of the π designs. If anyone has direct experience with this speaker (Black Widow 1808-8) in any of the &pi designs, I would welcome their comments.

Dan Marshal

The Pi plans should not be sold by anybody except Wayne Parham an I doubt that he has begun listing them on e-bay. Wayne gives the speaker plans to anybody who request them. He will e-mail them to you. This is very unfortunate as it is people doing things like this that will really screw-up a good thing!

You apparently misunderstood my post. I did not mention the plans being listed on eBay, rather, I asked whether the plans were available separately. What I did mention was that if my Peavey 18 inch speakers did not sell on eBay, perhaps I would consider the π design for enclosures for them, as the design, apparently, by virtue that some models use high Qts speakers, can accommodate speakers with fairly high Qts.

Dan Marshall

• http://www.MerryPranks.com

As I'm sure you're aware, the secret to using high Q motors is to use an open baffle or very large box. If they are installed in small boxes, the system will be underdamped, and as motor Q gets higher, optimal box size increases towards infinity. Accordingly, the cabinets for models using Alpha 15's are very large.

Welcome to the Pi forum. The Black Widows have similar T/S specs to some JBL speakers. I haven't used the 1808's but I have run 1505's before. They sound pretty good and if you end up keeping them they will be a good place to start. The 1505's had a good range and a clean sound, but I gave them up for JBL 2226's which have a little more punch and better dynamics.

Bill

Dan Marshall