diyAudio reference speaker project

Dave:
That speaker's the Krix Euphonix.

x. onasis:
Good to see you are still fidling with this speaker. I've heard a very good P17 + D25AG combo using a 1st order on the woofer and 2nd order on the tweeter crossing over at about 3000Hz.

I have to agree with Dave on the 0.5 woofer added to the back for BSC. After I tried it (on a different design), I'm now a convert. To do that to this design:
Vb=12 litres (leave the width at 170mm)
50 x 76 port (positioned about a third up from the bottom)
Fb=63Hz
F3=69Hz
0.5 woofer placed on back in line with front woofer
1st order xo to 0.5 rear woofer using 1.9mH inductor (BS 676Hz)
5uF cap still on tweeter and front woofer has no xo
This would be a different sounding speaker altogether with some useful bass especially with a bit of room loading. The mid bass and lower mids would really come alive.

Jay:
The series xo is not copyrighted. Zeta=1, 3225 xo, resistor in series 10ohm, inductor 0.7mH (DCR < 0.28ohm), 3.3uF cap. As with all series xo's, 1% calculations and 99% testing and tweaking. These are starting values only and drivers do lock in nicely with a series xo when you hit the sweet spot and even if you are a bit off as all that happens is the xo point and slope changes but the integration is always there.

Another one I've seen is 2800 xo, 0.42mH (DCR < 0.28ohm) inductor, 4.7uF cap, no resistor.
 
IMO few tweeters can be made to work well with a single cap, only the lowest-fs high-end ones that don't sound harsh when pushed hard. IMO the D27TG45 isn't one of them. Although it is described as being low-fs, AFAIK recent production units have consistently higher fs than spec. Thoughts?
 
Default WinISD box modeling of the P13 using Vifa specs and North Creek measured values:
 

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I've taken a hard look at the Peerless 850488. I must say a just-as-good alternative to the P13, maybe better, according to Linkwitz measurements. Results show much lower distortion figures than the P13, but not at the expense of a smooth frequency response and roll-off. This is a rarity in my book.

Well, I realize newbies don't care all that much for low distortion, but we're all for better speakers, right? And I suppose the Peerless is just as easy to cross over...
 
Hi coolkhoa

That tweeter's only available in Australia and basically is a special version of the 812687 and is supposed to be designed to compliment the HDS woofer........ sounds nice though. Has a rising response from 8kHz but levels out....... helps the off axis.

The Peerless 811827 would be OK but if I was doing it again I would use the SEAS 27TFFC or Vifa D27TG-45-06 or Vifa D25AG-35-06 as they would be more suitable for the series xo. The crossover would be different for these drivers and the last version I built of these had different values (R=9.2ohm, C=3.15uF, L=0.5mH) for a bit more laid back sound.
 
Bricolo said:
What about something with seas drivers
CA18RLY + 27TDFC
or for smaller ones, CA15RLY + 27TDFC


SEAS standard woofers (poly) should be easy to work with, but are they exceptional in any manner? Though a good alternative I'm sure...

BTW does anyone have measured parameters for Peerless 850488? Just curious to see how it measures up.:)
 
P13 MTM open baffle.

How about a MTM P13 and D27 ( or D25 ) open baffle with a sub.
Can the P13's go low enough to be crossed over to a sub ?
I know its only good to just below 100Hz in an enclosure . How bad can this get in open baffle mode?
Has anyone worked on the P13 in open baffle mode ?
Cheers.
Ashok.
 
Hi forum.

This thread is great. A big thanks to all the contributors and to Rabbitz for pointing to it.

A question on the small vifa box. I've a friend who worked the mines for a couple of decades and is subsequently a little deaf and has trouble hearing dialogue in movies with his (cheap sony cr*p) ht amp/speaker setup. Would these little tiddlers be beneficial for dialogue, say left, centre, right? He's not terribly interested in thunderous bass, just wants to know whats being said!

by Rabbitz

I have to agree with Dave on the 0.5 woofer added to the back for BSC. After I tried it (on a different design), I'm now a convert. To do that to this design:
Vb=12 litres (leave the width at 170mm)
50 x 76 port (positioned about a third up from the bottom)
Fb=63Hz
F3=69Hz
0.5 woofer placed on back in line with front woofer
1st order xo to 0.5 rear woofer using 1.9mH inductor (BS 676Hz)
5uF cap still on tweeter and front woofer has no xo
This would be a different sounding speaker altogether with some useful bass especially with a bit of room loading. The mid bass and lower mids would really come alive.

Would the added volume be using height only or a combination of HxD?

Newb Q coming through... Is the rear woofer/mid mounted facing the rear like a mirror image to the front baffle, or is there some voodoo internal mouting thing happening there?

Cheers
Kendal.
 
frugal-phile™
Joined 2001
Paid Member
lazyfly said:
Would the added volume be using height only or a combination of HxD?

Newb Q coming through... Is the rear woofer/mid mounted facing the rear like a mirror image to the front baffle, or is there some voodoo internal mouting thing happening there?

With the width of the baffle fixed, the extra volume would be from increasing height & depth.

The only voodoo going on inside is a brace (often a dowel, or other piece of wood) tightly joining the 2 woofer magnets. And any extra bracing you feel is necessary because the box is bigger.

dave
 
lazyfly said:
A question on the small vifa box. I've a friend who worked the mines for a couple of decades and is subsequently a little deaf and has trouble hearing dialogue in movies with his (cheap sony cr*p) ht amp/speaker setup. Would these little tiddlers be beneficial for dialogue, say left, centre, right? He's not terribly interested in thunderous bass, just wants to know whats being said!

If he's after clear dialogue you could hardly find a better mid woofer than the P13WH and with the small bass output would make it easier for him to hear the dialogue. For this use just go with the standard design without the 0.5 woofer on the back but have the boxes close to the wall.

If making a centre check on shielding requirements as none of these drivers are shielded. Sitting on axis would not require a centre speaker and just use the phantom mode (or whatever it's called these days) with the L/R speakers 1.5m - 2m apart.

Next week I'll be posting a series xo alternative(s) for these speakers.

Cheers
Rabbitz
 
Ok, i've been following this thread with some interest as i've been contemplating building a set of speakers for some time. I've finally taken the plunge and bought some drivers to do this with, and now i just have to make them work together.

As convienient as building a kit would have been, i've opted to design them myself (when confronted with two paths, always choose the most treacherous).

What i've chosen so far are the Peerless 850122's and the Vifa XT25's for the upper two way, and a Peerless 12" handling lower bass in a seperate cabinet (all sealed). All pretty cheap and they should work well enough.

All through this thread people have been waxing and waning on the subject of the XT25, but noone has gone into any detail on how to make it work properly (i bought them because they were cheap enough, and i could use thier purchase to justify the recent purchase of an SACD player). Any information would be greatly appreciated. to add to the drama, i'm going to tri-amp:xeye:, so any suggestions on how to make this all work received gratefully:)

I really hope more people take the plunge and give this tweeter a try. I think it has the potential to awesome for very little outlay.

Thanks
 
It's a shame none of these drivers are sheilded.. that woudl be even better for a lot of newbies , who might want to use such a small speaker system with the PCs.. maybe even next to TVs for home theater.

I notice vifa have quite a few sheilded models, but i havent researched there suitablitly in a good system, with small enclosure. I dont supose anyones allready done so at some stage in the past ?
 
Shielding is only required if your speaker is extremely close to the TV set or PC monitor. I've got some bookshelves which are not shielded in a system that's only about 400mm away from the TV and never had a problem, even with trying them sitting next to the TV.

By the time you place you speakers apart for some sort of soundstage, you're not going to be near the TV at all.