Home/Pro 8" 2-way: RS28A and B&C 8BG51

[300Z]

Thank you very much!

[hongrn]

I'm not Jeff, but here you go:

http://audio.claub.net/software/FRD_Blender/Blender.html

[300Z]

Re: Home/Pro 8" 2-way: RS28A and B&C 8BG51



For what it's worth, at last week's Loudspeaker Design Workshop I gave a presentation on how to get quasi-anechoic frequency response in your room that is completely accurate down to 10Hz with no room interactions at all. It requires taking two measurements that I defined precisely how they are to be taken, and putting them together using a tool that Charlie and I put together. I stated that the conventional method of splicing does not result in an accurate frequency response, and graphs like the one pictured in Joe D's book on Measuring Loudspeakers is incorrect, but I showed that my method produces a correct frequency response that you can verify fairly easily. I need to write this process up in a paper. This new method is one of the special treats I gave the group last week. It was the first time this has been presented anywhere, and I have never seen this methodology presented anywhere I have ever read, online or in a book, so I think what I have is a new twist on the subject.

Jeff B.

Hi Jeff, I was wondering if it would be possible I could get a copy of your presentation on how to get quasi-anechoic frequency response measurement.
I tried to send you a PM but that didn't work and I don't know your email.
Thank you.

[Face]

Sorry, no spares.

[Pete Schumacher]

Scanspeak's small face plate Illuminator tweeters should work as well(1" only).

I'd probably have to modify the guide a bit, make the opening a little smaller. Right now it's 1.625" diameter in order to match up with the small chamfer at the edge where mesh meets flange on the RS28A./F. It would be nice to try though. Anyone care to send me a Beryllium Illuminator to try out?

[Face]

By the way, that guide/baffle should work for any 28mm tweeter with a flat flange. The Usher tweeters work well as does the SEAS 27TBFC/G. The grid shield on the SEAS fits perfectly in the opening just like the RS28A. Of course, the crossover would have to be tweaked and I doubt the B&C woofer can be properly matched to the SEAS tweeter due to the earlier roll off of the SEAS unit.

Scanspeak's small face plate Illuminator tweeters should work as well(1" only).

[filmslayer]

If you can find a local CNC shop, I could send them the cut file and they could crank it out for you.

And thanks for the compliment on the look of the speaker. Ryan Scott painted the baffle for me. And the cabinet is obviously one of PE's now discontinued piano black gloss curved .75cf cabinets.

how about you just keep me in mind for a set if others want some ? i'm in the middle of 3 projects right now and would not be able to get to these for a while and i'm sure the more you have done the less expensive they'll be ....

***Edit - i've been looking for a local CNC shop but not having any luck ...

[Pete Schumacher]

Here's the power compression test. First plot is the .1W, 1W and 10W outputs. Second plot is the deviation from ideal between the .1W and 10W plots. I removed 20dB from the 10W plot and then divided the .1W curve by the 10W curve. 10W is approximately [email protected]

This is a pretty darn linear system to say the least.




That deviation from ideal shows how well that RS28A performs in this guide. Keep in mind that the crossover point is ~1100Hz LR4.

I'll work on getting some off axis plots next.

[Pete Schumacher]

By the way, that guide/baffle should work for any 28mm tweeter with a flat flange. The Usher tweeters work well as does the SEAS 27TBFC/G. The grid shield on the SEAS fits perfectly in the opening just like the RS28A. Of course, the crossover would have to be tweaked and I doubt the B&C woofer can be properly matched to the SEAS tweeter due to the earlier roll off of the SEAS unit.

[Pete Schumacher]

i would be interested Pete , but don't go outta your way just for me ....

If you can find a local CNC shop, I could send them the cut file and they could crank it out for you.

And thanks for the compliment on the look of the speaker. Ryan Scott painted the baffle for me. And the cabinet is obviously one of PE's now discontinued piano black gloss curved .75cf cabinets.

[filmslayer]

i would be interested Pete , but don't go outta your way just for me ....

[Pete Schumacher]

that is a nice looking speaker !

is the guide available or is it something you milled ?

It's a custom made baffle. I drew up a CNC cut file and had it done here locally at a custom cabinet shop on their CNC. If you're interested, I can have some more cut. Not positive on the price though. It all depends on how many I get cut at once. I'll have to order a 1" sheet of Plum Creek MDF since I ran out of that stuff a while back.

[filmslayer]

that is a nice looking speaker !

is the guide available or is it something you milled ?

[Pete Schumacher]

That's very generous.

This was always intended to be a publicly available project.

I'll try and get some off axis plots in the next couple days, and maybe a power compression set as well (.1W, 1W, 10W)

[Pallas]

That's very generous.