diyAudio reference speaker project - Page 21 - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

Multi-Way Conventional loudspeakers with crossovers

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 26th October 2006, 09:42 PM   #201
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
Basically an OEM P17 VIFA did for PSB. And given the source either rejected or surplus. Not much use above 2k.

No pictures handy.

I figure 300 Hz or so XO.

dave
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA
  Reply With Quote
Old 28th October 2006, 04:30 AM   #202
suzyj is offline suzyj  Australia-Aboriginal
diyAudio Member
 
suzyj's Avatar
 
Join Date: Jan 2006
Location: Sydney
Hi guys,

Here's my versions of Rabbitz' speakers (with no veneer as yet).

Click the image to open in full size.

They're made from 16mm MDF, with 4mm deep rebates in the top, bottom, and side. It's probably excessive complexity, but it makes them really well sealed.

Click the image to open in full size.

I put a 16mm radius on the front sides, mainly because I thought it looked nice. They're wonderfully dense little speakers - each one weighs about 5kg. It's been a blast playing with my router.

Now I get to play with crossovers

Cheers,

Suzy
  Reply With Quote
Old 28th October 2006, 12:47 PM   #203
rabbitz is offline rabbitz  Australia
diyAudio Member
 
rabbitz's Avatar
 
Join Date: Jul 2003
Location: Newcastle, Australia
Cool.... another almost coming to life..... well done. I'm quite partial to radii on the vertical front edges. Which xo are you going to use?

When you get the xo done, I'll be interested in your listening impressions.
__________________
No longer DIY active
  Reply With Quote
Old 28th October 2006, 02:49 PM   #204
contour is offline contour  Netherlands
diyAudio Member
 
Join Date: Apr 2006
Location: rgwer
Hello,

Of course I would advise that you, just as I did, try the several crossovers posted in this threat. But if you are looking to the best result I think you will also find the AR series crossover to sound best.

Try to use the best components that you can affort. As I understood the small coil in parallel to the tweeter needs to be very good quality (I use a copperfoil coil). For the big coil in series with the woofer you also need a good one (I used a 2.0mm2 coil wounded with a wire that consists out out 7 seperate wires).

I am not sure how important the capacitor is. A very good one of 22uF will cost serious money. I used a 22uF 400V MKP first but now I have added a 4.7uF 800V and 0.1uF 1200V in parallel. This gives a little smoother sound in my opinion. Here is my crossover (I know it looks a bit messy but it is difficult to get the components in and solder true the small woofer cutout):

http://img76.imageshack.us/img76/7360/pa260058hq0.jpg

Best regards,

Walt
  Reply With Quote
Old 28th October 2006, 10:40 PM   #205
suzyj is offline suzyj  Australia-Aboriginal
diyAudio Member
 
suzyj's Avatar
 
Join Date: Jan 2006
Location: Sydney
I'll certainly try a few different crossovers. Probably a 4.7uF cap for starters, and the AR series crossover. I've also been thinking about a simple 12dB/octave parallel crossover (a simplification of the Esquire crossover) with 4.7mH inductors and 6.8uF caps, and the tweeter padded out a tad to account for its higher efficiency and lower impedance, using a 22Ohm resistor across the tweeter, with a 3.3Ohm resistor in series.

I'm a little leery of using really huge low resistance inductors. The woofer Re is 5.7Ohms. Surely once you get down to a few hundred milliohms you're not going to see any difference (except perhaps for reducing the enclosure volume with an enormous inductor).

Cheers,

Suzy
  Reply With Quote
Old 28th October 2006, 11:07 PM   #206
suzyj is offline suzyj  Australia-Aboriginal
diyAudio Member
 
suzyj's Avatar
 
Join Date: Jan 2006
Location: Sydney
Default AR Crossover

I've been simulating different crossovers with LTspice (using a 6Ohm resistor to approximate the tweeter and an 8Ohm resistor to simulate the woofer).

The AR series crossover gives a surprisingly low crossover point of around 800Hz. Is this deliberate? The Esquire has a crossover point of 3KHz.

Anyway, I halved the value of the inductors and capacitors, and came up with L1=0.68mH, L2=0.047mH, C1=10uF, and R1=6R8, and increased the crossover point to 1600Hz.

It's certainly a very kind crossover on amplifiers, as the minimum impedance is 8 Ohms, rising to 10 at high frequencies. The parallel crossover has a dip at the crossover point to about 4R5.

Cheers,

Suzy
  Reply With Quote
Old 29th October 2006, 01:33 AM   #207
Geoff H is offline Geoff H  Australia
diyAudio Member
 
Join Date: Oct 2006
Hi Suzy, nice work on the speakers. Keep the x-overs simple. Start at the half way point of the 3db down points of both drivers, and start with 6db/octave.
Somewhere I recently saw a novel idea for the hi-pass where attenuation is required. A series resistor to match sensitivity, and a shunt inductor to control the 3db down point of the tweeter. The shunt inductor should dampen the lower resonance of the tweeter.

BTW. The ETI477 fired up OK. Iq a bit high, heatsinks went to 80 odd degrees in 20 minutes!

Geoff.
  Reply With Quote
Old 29th October 2006, 09:07 AM   #208
contour is offline contour  Netherlands
diyAudio Member
 
Join Date: Apr 2006
Location: rgwer
Hello,

I am not sure about the crossover frequency of the AR crossover but with this filter the tweeter seems less stressed than with the single 4.7uF capacitor.

Did you use the measured impedance graph of both tweeter and woofer in your simulation? (Obviously using the DC resistance will give a wrong result)

As mentioned on the AR website the small parallel coil should almost always be 0.11mH for Vifa and Scan Speak tweeters. I did an RTA measurement and the AR crossover measured very flat both on axis and off axis.

Best regards,

Walt
  Reply With Quote
Old 29th October 2006, 09:56 AM   #209
suzyj is offline suzyj  Australia-Aboriginal
diyAudio Member
 
suzyj's Avatar
 
Join Date: Jan 2006
Location: Sydney
Quote:
Originally posted by Geoff H
BTW. The ETI477 fired up OK. Iq a bit high, heatsinks went to 80 odd degrees in 20 minutes!

Geoff.
Either the bias is set _way_ high, or it sounds like it might be oscillating. Before I had my AEM6000 tamed, it'd get pretty warm. Now the heatsinks run warm, but by no means hot.

Cheers,

Suzy
  Reply With Quote
Old 29th October 2006, 11:54 AM   #210
rabbitz is offline rabbitz  Australia
diyAudio Member
 
rabbitz's Avatar
 
Join Date: Jul 2003
Location: Newcastle, Australia
Default Re: AR Crossover

Quote:
Originally posted by suzyj
The AR series crossover gives a surprisingly low crossover point of around 800Hz. Is this deliberate? The Esquire has a crossover point of 3KHz
The AR xo crosses over at about 3400Hz.

You can't use the nominal impedance when working out the xo point and the impedance of the woofer and tweeter are around 15R and 5R3 respectively at the xo point. Series xo's need a low DCR in the inductor (protects the tweeter) and as a general rule it should be less than 5% of the driver's Re in any type of xo, series or parallel (Thiele's reasoning).

Have a look at the AR xo page for some background on this type of xo and Andy G's info on series xo's.

Contour
Great to hear some feedback on the crossovers you tried and IMO the AR does have the edge as you reported.
__________________
No longer DIY active
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



New To Site? Need Help?

All times are GMT. The time now is 10:32 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2