Arpeggio Write-up is done and here

[shawn_a]

For those who were/are/might be interested in my Arpeggio project (Usher 8948A and 9950-20), here's the link for the basic write-up. Sorry it took so long to get out.


http://files.me.com/labradork/4gvno9


shawn

[rudyjakubin]

Re: Arpeggio Write-up is done and here

COOL... Pretty straight forward crossover. A classic 8 ohm two-way as far as values go. Only that 8 ohm resistor in the woofer leg suggests it was to contour the baffle step droop.
Could even be just a simple zoebel... Nice pics, the only complaint I have is no pretty box with them pretty drivers on a shiny baffle...
Now you got me to wanting to hear a pair of Usher tweeters...;)

[lunchmoney]

Re: Arpeggio Write-up is done and here

pix!

[Wolf]

Re: Arpeggio Write-up is done and here

pix!

The ones in the middle:



Later,
Wolf

[Operandi]

Re: Arpeggio Write-up is done and here

Nice design, very minimalist, need to see some pics though. This kinda what I'm looking for for my next project but maybe a bit expensive at the moment.

Do designers often start a design solely by ear? I assumed these days everyone started with simulations.

*edit*

Just saw the pics, very nice looking indeed.

[shawn_a]

Re: Arpeggio Write-up is done and here

The ones in the middle:



Later,
Wolf

Thanks for posting that for me, buddy. I'll have more pics of them on my website when time allows. Keep in mind though, what you see now are nowhere close to what I have in mind for the finished project. I just wanted to get the write-up posted for those interested in them.

shawn

[Wolf]

Re: Arpeggio Write-up is done and here

Thanks for posting that for me, buddy. I'll have more pics of them on my website when time allows. Keep in mind though, what you see now are nowhere close to what I have in mind for the finished project. I just wanted to get the write-up posted for those interested in them.

shawn

Yeah, *I* know it's not the final aesthetic, but a visual always helps.
Not a problem,
Wolf

[romanbednarek]

Re: Arpeggio Write-up is done and here

Thanks for posting that for me, buddy. I'll have more pics of them on my website when time allows. Keep in mind though, what you see now are nowhere close to what I have in mind for the finished project. I just wanted to get the write-up posted for those interested in them.

shawn

It is tough to see from the picture but it looks like the tweeter is located nearly equidistant from three sides of the baffle (left, top, right) which usually isn't the best configuration in terms of diffraction issues (it falls into the category of "Worst Case Scenario" on my page on tweeter diffraction, pic and link below...)



http://www.rjbaudio.com/Audiofiles/t...ffraction.html


I'll mention, however, that one of my favorite speakers (Asterion, shown below) which happened to be an early project has the tweeter similarly spaced but is 1/2" closer to the top of the baffle than the sides.

[curt_c]

Re: Arpeggio Write-up is done and here

It is tough to see from the picture but it looks like the tweeter is located nearly equidistant from three sides of the baffle (left, top, right) which usually isn't the best configuration in terms of diffraction issues (it falls into the category of "Worst Case Scenario" on my page on tweeter diffraction, pic and link below...)



http://www.rjbaudio.com/Audiofiles/t...ffraction.html

I postulate that Shawn voiced these positioned with little or no toe in. This would smooth the diffraction effects on the listening axis.

C

[romanbednarek]

Re: Arpeggio Write-up is done and here

I postulate that Shawn voiced these positioned with little or no toe in. This would smooth the diffraction effects on the listening axis.

C

Good point!

[Paul K.]

Re: Arpeggio Write-up is done and here

The first couple of times I used the link to your writeup, I couldn't get there for some reason, but I just did a bit ago. Your writeup was not only good, but fun reading, and I think you quite nicely achieved your goals for this design. I sure do like the 8945Ps in my Marcatos and I suspect your Usher woofers sound equally good (I assumed you played then there but I can't remember how they sounded at InDIYana). Really nice job, Shawn.
Paul

[shawn_a]

Re: Arpeggio Write-up is done and here

I postulate that Shawn voiced these positioned with little or no toe in. This would smooth the diffraction effects on the listening axis.

C

You got it, Curt. I voiced them with no toe-in quite by accident actually. It's just the way things happened one night and I never changed the arrangement out of consideration of continuity. Still they came together well enough in my estimation.

shawn

[shawn_a]

Re: Arpeggio Write-up is done and here

It is tough to see from the picture but it looks like the tweeter is located nearly equidistant from three sides of the baffle (left, top, right) which usually isn't the best configuration in terms of diffraction issues (it falls into the category of "Worst Case Scenario" on my page on tweeter diffraction, pic and link below...)



http://www.rjbaudio.com/Audiofiles/t...ffraction.html


I'll mention, however, that one of my favorite speakers (Asterion, shown below) which happened to be an early project has the tweeter similarly spaced but is 1/2" closer to the top of the baffle than the sides.

Yeah, you caught my boo-boo there, Roman. I didn't plan on the tweeter being centered like it is but I fudged a number in my layout and there I was. I broke a lot of little "rules" on these, with the centered tweeter and no edge treatment on the baffle, but they came out well enough and don't seem to suffer. For it being a proof-of-concept kind of run through I just wanted to get them this far before the heavy-duty final design was executed. When I do manage to get them in the final enclosure I'm going to be interested in hearing how this crossover performs with a more "proper" enclosure.

shawn

[shawn_a]

Re: Arpeggio Write-up is done and here

The first couple of times I used the link to your writeup, I couldn't get there for some reason, but I just did a bit ago. Your writeup was not only good, but fun reading, and I think you quite nicely achieved your goals for this design. I sure do like the 8945Ps in my Marcatos and I suspect your Usher woofers sound equally good (I assumed you played then there but I can't remember how they sounded at InDIYana). Really nice job, Shawn.
Paul

Hi Paul
Thanks for the compliments. These didn't make it to InDIYana this year but I sure wanted to have them there to compare directly with the 8945 projects. I really like the way both the 8948 and 8945 woofers perform. The 8948 is very easy to work with and I'm still considering getting a pair of the 8945P woofers to play with out of curiosity.

shawn

[Mark65]

Re: Arpeggio Write-up is done and here

Yeah, you caught my boo-boo there, Roman. I didn't plan on the tweeter being centered like it is but I fudged a number in my layout and there I was. I broke a lot of little "rules" on these, with the centered tweeter and no edge treatment on the baffle, but they came out well enough and don't seem to suffer. For it being a proof-of-concept kind of run through I just wanted to get them this far before the heavy-duty final design was executed. When I do manage to get them in the final enclosure I'm going to be interested in hearing how this crossover performs with a more "proper" enclosure.

shawn

Hey Shawn, have you or anyone else that you know of done a project with these drivers that *follows* all the rules? Edge treatment, proper placement, diffraction and xo modeling, all that jazz?

I'd be interested in seeing the differences in the parts count, layout, and FR curve, as well as get your impressions on the sonic differences.

That said, I really like your writeup, and the project as a whole. I'd love to be able to do a project with some higher end drivers like that someday...not holding my breath, though!:D

Good Stuff!

Mark