Brutus: concept with vintage Philips drivers

[arjank]

Hi folks, I have been busy some time with the concept of a pretty big loudspeaker that will make use of vintage Philips loudspeakers.
The loudspeaker will contain two 12" woofers, a 12" fullrange unit, and a polycarbonat dome combined with an 8" Dayton waveguide.
I allways wanted to make a "super" loudspeaker with vintage Philips stuff. The 12" fullrange e.g. is one of the best 12" fullrange units out there.
One of the main things is to not make a "huge" cabinet, the only concept for the two 12" woofers is to put them in a highpass filtered closed box. This way the enclosure for the two woofer will be about 70 liters. The 12" fullrange unit will have an open enclosure that will be damped pretty heavy.

On a dutch DIY site I have explained the whole concept, I will translate the most important parts and will put them on this forum. For those who want to take a peak of the concept here is the link forum.zelfbouwaudio.nl • Toon onderwerp - Philips 2x12"woofer, 12" breedbander en poly-dome (Tractrix) . Allthough it is in dutch language there are a lot of pictures of the units, measurements, simulations and the design that will speak for themselves.

[arjank]

Here are some pictures of the concept and an overview of the drivers

[Jonathan Bright]

Hi arjank. Looks like fun! In the early 1970's Philips drivers were one of the few options for diyers in Australia. My first pair of speakers were a Philips diy 8" 3way with those tweeters. I have no idea what they sound like with a wave guide but they were noticeably better without the black plastic bit. (But I guess you guys know these units back to front.)
I recently bought a pair of 12"/5"/1" three ways second hand and re-boxed the bass unit for one of my kids. they had to be 30+ years old and they were excellent.

[arjank]

Here are some pictures of the AD0160/T4 Philips tweeter and the 8" waveguide.
You see some measurements of the original(unmodified) tweeter, damn good for a 40 year old speaker
To make it perform better I changed the damping behind the dome with felt, this smooths out the high peak around 14khz.

Tweeter+waveguide
It took me some time to smooth out the transition between the faceplate and waveguidethroat. The measurements of the tweeter and waveguide are with a xover (18dB/oct). The xover would normaly make for a xover frequency of approx. 4khz, but with the waveguide it is 1.3khz
On axis the top end(above 10khz) looks a bit nasty, but the more you move off-axis the smoother it gets.
And how does it sound? I made a test setup with the Ad12100/M8 fullrange driver and the tweeter+waveguid crossed at 1.3khz. Man, it sounds great! Very life like and lots of detail. All I can say that the sound is addictive, I still want to listen to it I have made speakers with other more expensive drivers but they don't sound nearly as good as this.

[Zen Mod]

I just read entire thread on dutch forum

great !

I'm big fan of old Philips drivers , and have several pairs of them

have you , by any chance , measured T/S for 12100/M8 ?

TIA

[arjank]

have you , by any chance , measured T/S for 12100/M8 ?

You're in luck, yes I have

Thiele Small Parameters AD12100/M8

Fs 36Hz
Re 7,1ohm
Qes 0,558
Qms 2,763
Qts 0,464
Vas 193,3 ltr
Mms 31,6 g

calculated Rms 2,59 kg/s

Spl 93,8 dB

[Zen Mod]

[arjank]

Here are two pictures of the test setup I wrote about earlier
It looks awfull, I know, but it was all about functionality. The AD12100/M8 speaker is in a tapered open enclosure, the perfect cabinet for this driver. It doesn't produce any deep bass(that will be done by two other 12" woofers) but the mid/bass that's coming out of this setup is amazingly punchy.
The Ad12100/M8 is filtered by a 3,3mh inductor and a notch to dampen the 2khz bump thats created by transition of the cone to the whizzer cone. It couples perfectly at 1.3khz with the Ad0160/T4 in the waveguide. Soundwise it's very open, detailed and voices sound very, very realistic. I invited some musicians to listen to it and they were amazed. One of them has Dynaudio Studio monitors, he said that they could not produce such a life like experience

[arjank]

Here is the impance plot of the AD0160/T4 in the waveguide.
The Fs is pretty low (880hz), and there are no strange artifacts

[arjank]

The low-end of the concept.
In the design I will use the AD12100/W8 and the AD12200/W8.

The AD12100/W8 is a 12" woofer from the early 70's, it has a nice rubber surround, a 2" voice coil, a paper voice coil former, 5mm xmax

The AD12200/W8 is a 12" woofer from the early 80", it has a rubber surround, a 2" voice coil, a aluminium voice coil former, 5mm xmax

After measuring the AD12100/W8 I noticed a pretty low Qms (means high mechanical losses) allthough it has a paper voice coil former. After swapping the dustcap for a porous one the Qms got twice as high After the modification the calculated Rms got as low as 1,85 kg/s, which is very low for a 12" woofer. Below you'll find the TSP's of the original and the modified AD12100/W8 as well as the TSP's of the AD12200/W8.

Thiel Small Parameters AD12100/W8 unmodified:

Fs 23Hz
Re 6,8ohm
Qes 0,298
Qms 2,153
Qts 0,262
Vas 258,3 ltr
Mms 61,4 g


Thiel Small Parameters AD12100/W8 with porous dustcap:

Fs 22Hz
Re 7ohm
Qes 0,338
Qms 4,603
Qts 0,315
Vas 273,6 ltr
Mms 61,4 g


TSP's AD12200/W8.

Fs 21Hz
Re 6,4ohm
Qes 0,328
Qms 4,062
Qts 0,304
Vas 287,4 ltr
Mms 70,4 g