Home » Sponsored » Pi Speakers » 6Pi - 7Pi bass cab same dimensions?
6Pi - 7Pi bass cab same dimensions? [message #53271] Sun, 01 March 2009 19:33 Go to next message
Psychoacoustic is currently offline  Psychoacoustic
Messages: 75
Registered: May 2009
Viscount
As per the subject title- I have 6Pi plans but intend to build 7Pi. Are the bass cabinets the same dimensions? If not, may I request the 7Pi plans, please?
Thanks, Ant.

Close, but not the same [message #53272 is a reply to message #53271] Sun, 01 March 2009 20:56 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18783
Registered: January 2001
Illuminati (33rd Degree)

They're close enough in volume that either would work for the other if the Helmholtz frequency were right. That's the main thing, the cabinets are tuned to a different frequency. They are a slightly different volume as well.


Re: Close, but not the same [message #53275 is a reply to message #53272] Sun, 01 March 2009 22:10 Go to previous messageGo to next message
Psychoacoustic is currently offline  Psychoacoustic
Messages: 75
Registered: May 2009
Viscount
Wayne, thanks again for the response and plans. Getting closer to the build... couple more questions.

I understand that this has been done to death, but one more time please...
In Japan, I can only source 10mm ply. The plans call for 20mm (3/4").
For the Pi7 specifically, would gluing two 10mm ply sheets together or one 10mm ply and one 10mm MDF be better, or no difference?

Recently, there was some discussion of crossover value changes. Do you have these updated, populated crossovers ready to go?

PaulW, who has built the Pi7, mentioned enlarging the mid-horn flare dimensions. Any thoughts on this?
Thanks again.

Re: Close, but not the same [message #53278 is a reply to message #53275] Mon, 02 March 2009 00:18 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18783
Registered: January 2001
Illuminati (33rd Degree)

For plywood, I'd use 18mm which is very close to 3/4". It's about 0.7"

About crossovers, we stock assembled circuit boards using a variety of optional components. You can choose from Jantzen, Auricap, Mills, etc. We also sell unpopulated crossover PCB's if you'd rather assemble your own.

About the midhorn, PaulW wrote to me some time ago when he was assembling his. He was concerned about how to mount them in the box, wondering how to trim them out. I suggested a hardwood trim that serves as a sort of edge band. The idea is to cut it to have the same angle as the flare. It is attractive and it extends the flare slightly, which isn't a bad thing. I think that's probably what you're talking about.

The midhorn is designed to be as small as possible without sacrificing sound quality. Even still, they're fairly large. Making a horn larger isn't generally a problem, it's making it smaller where you'll run into complications. You could make them larger, if you wanted, but when used in the corner, the walls tend to act as flare extensions anyway.


Oh, my mid-horn mkII idea [message #53281 is a reply to message #53278] Mon, 02 March 2009 17:05 Go to previous messageGo to next message
PaulW is currently offline  PaulW
Messages: 71
Registered: May 2009
Location: UK
Viscount

Child art added to give an idea of what I'm thinking of.

Indeed that was the context the mid-horn size got raised - and I never did use the edging method. But it was mentioned that the flare would benefit from being slightly bigger so, when I get round to remaking it I was going to increase the throat to corner distance by 1 inch with the top and bottom faces slightly curved to the middle with a 2 inch increase. The 'drum' holding the driver would be made from flexible MDF (MDF sheet with slots cut 2/3's the way through the thickness at regular intervals) formed over disc of ply. Well that's the plan, but then again, there's the power-amp upgrade, the preamp upgrade......

Paul

Re: Oh, my mid-horn mkII idea [message #53282 is a reply to message #53281] Mon, 02 March 2009 17:12 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18783
Registered: January 2001
Illuminati (33rd Degree)

The rear chamber shape is not so much an issue, you can make it however you want. As far as the size of the flare is concerned, it's not necessary to make it any bigger if it will be used in corners as intended, but it won't make it any worse either. If you change the angle of the walls, that will change things, both in terms of radiating pattern and probably the shape of the response curve too.


Re: Oh, my mid-horn mkII idea [message #53283 is a reply to message #53282] Mon, 02 March 2009 17:27 Go to previous messageGo to next message
PaulW is currently offline  PaulW
Messages: 71
Registered: May 2009
Location: UK
Viscount
The angles of the walls will remain the same, just the curved front and a 1 inch overall throat to edge increase.

Paul

You may now graduate to finger-painting [message #53284 is a reply to message #53283] Mon, 02 March 2009 18:07 Go to previous messageGo to next message
Psychoacoustic is currently offline  Psychoacoustic
Messages: 75
Registered: May 2009
Viscount
Paul, there's a huge underground market for naive art. Your design is aesthetically pleasing, unlike my attempts at writing Japanese, which the locals can only translate as "a monkey choking a squirrel", etc.
Any thoughts on how you will mount the HF driver?
I think I remember reading in your review that you felt the drivers blended seamlessly. But I promise I'm not making this up, I read in this forum some talk of altering crossover points... buggered if I can find the post.

Front edge trim on midhorn [message #53285 is a reply to message #53283] Mon, 02 March 2009 21:27 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18783
Registered: January 2001
Illuminati (33rd Degree)

Oh, I see, well there you go! That's pretty much how mine are done too, with a 1" trim that covers the entire front. It's there mostly for aesthetics, but it doesn't hurt that it effectively makes the horn a smidge larger. You can see the front edge trim pretty well in this photo:

seven π midhorn and tweeter


Re: You may now graduate to finger-painting [message #53286 is a reply to message #53284] Tue, 03 March 2009 05:00 Go to previous messageGo to previous message
PaulW is currently offline  PaulW
Messages: 71
Registered: May 2009
Location: UK
Viscount
To mount the HF horn I would use a "T" shaped platform attached to the front/top of the horn in-line with the original dimensions, supported by the triangular brace. A similar method below to support the mid on the bass unit. Still all a bit academic at the moment as these are just ideas in my head and on the doodle pad!

Don't remember any posts about altering crossover points TBH, the end result with mine is impressively cohesive as it stands - I certainly can't hear the joins ;¬)

Paul

Previous Topic: 7pi XO points
Next Topic: plans for Pi 4
Goto Forum:
  


Current Time: Tue Nov 05 17:22:36 CST 2024

Sponsoring Organizations

DIY Audio Projects
DIY Audio Projects
OddWatt Audio
OddWatt Audio
Pi Speakers
Pi Speakers
Prosound Shootout
Prosound Shootout
Miller Audio
Miller Audio
Tubes For Amps
TubesForAmps.com

Lone Star Audiofest