Philips semi OB question(s).

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Last year I build a semi open baffle with BR sub. This is my first serious build.

I used Philips to units to build it. The units are:

AD 121000M/8
AD 121000W/8
AD 0160T/8
(see attachment for filter)

The sub has a 85 litre (about 82 litre without filling/ lining) BR cabinet.
The baffle is 38cm /15inch wide and 120cm/47.2 inch wide

On a Dutch forum I found someone who could help me since I don’t have any experience in building speakers. Size wasn’t that important but I wanted the wide as small as possible. The result is seen in the pictures.

It sounded great! But after a while I found it something dull. So the simple experimenting began. I changed the cap on the tweeter (2,2uf), removed the coil on the AD121000m/8. And the sound sounded much more “fresh”.

I added straight wings, first extending to the rear after that I widened the baffle to 60cm/23.6 inch using some thin floorboards. This improved the sound even further. The Bass was far more prominent and a bit clearer/deeper.

This improvement got me thinking that there must be ideal design, since ideal isn’t always practical my question(s) are:

1. Must I build another design (I am open for that)? Or
2. Do I just increase the wide off the baffle (and how much)?

3. Now the speakers (except the tweeter) are flush with the baffle, if I add another layer to widen the baffle this is no longer the case (say 9mm/0.4inch).

4. The tweeter now has its place on the baffle is this right or do I place this in a separate small housing, or do I place it somewhere else on the baffle).

5. Do I lose the BR cabinet all together?

6. Or is it “pretty” ideal right now? (or must i forget it all together...:)

Extra notes:

A new build is a possibility
I am on a tight budget so extravagant filter parts are not possible
The design can be wider (60cm
For now I am using a (Arjen Helder) Ta2020 amplifier or Peter Daniel LM4780 (the first gives better results)
 

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The tweeter AD160 is a decent tweeter but it needs a proper crossover. But it need more than a cap as a crossover. The black line is the tweeter with no crossover. Red is with a serial cap cutting at 6 kHz. At 3 kHz it is 6 dB down as it should at 1500 Hz -10dB instead of 12 dB not bad. But at 750 Hz It should be 18 dB down instead it is only about 3 dB. This is terrible and will add a lot of strain on the driver even if it adds "brightness" to your speaker



-18 dB would mean that the driver would get less than 2% of the power at 750 Hz instead it gets about 50%.My guess is that the AD160 has to low sensitivity to keep up with the 12" unit and that you need a more sensitive tweeter. If you have a 4 Ohm unit you get 3 dB more for the same voltage.
 
So the simple experimenting began.

In order to improve your speaker, you first have to find out what's good and what's not. Otherwise the chance to succeed is not very big.:)

Attached is a simulation of your current setup (microphone distance 3 m). The simulation is not meant to be very accurate, because reliable data of the drivers (TS-parameters, impedance and SPL response) are missing. But it gives a basic understanding of the actual situation anyway.

The woofer section seems to be OK and the low-pass filter basically works. I did assume a port of 70 mm in diameter and 100 mm in length. What are the actual dimensions of your port? A free air impedance measurement of your woofers is absolutely necessary to definitely say more.

The tweeter section doesn't look good. It certainly can be improved by proper flush mounting of the tweeter and by a better crossover. Check the report of Troels Gravesen: WWDT. However, the sensitivity seems to be just sufficient.

Finally the midrange section is the biggest unknown in your speaker. Clearly the crossover is poor. The first order high-pass filter causes a peak at the resonance frequency (same problem as in the tweeter filter) and the 1 mH coil cuts the frequency response much too early.

From that I conclude that you don't have to build a new cabinet, but you have to focus on improving the crossover.
 

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Thanks! for your replies! I must admit that before I began this project I found many articles also the one by Troels Gaveresen. The problem is I am bad at reading this kind of articles. I am more the trail and error type.
When i have an error and talk about it than the shown diagrams make more sense to me.

The part "From that I conclude that you don't have to build a new cabinet" I like the second part "but you have to focus on improving the crossover" is a bit of a downer..... but in the back of my head I taught this (among others) was the case...

To give some answers on your questions.

-The (rear firing port(s) are 2 ports on each cabinet of 65mm wide and 100mm deep. I can't find the papers on that decision. I know this was convient because this is standard a sewage pipe dimension. (shorten or extending them is hard, they can't come loose).

- I can find the Vifa's they are on sale nearby.

-I like the overall sound enormously but when I have to be strict:

The bass is nice and firm, but on the longer parts it seems to rumble a bit. The later added extensions to the baffle seem to have the effect that the bass is more clear and a bit lower...

-The highs are ok... but they draw my attention to the left and the right while the rest of the music is playing on a beautiful stage in the room. Let say the drummer is somewhere in the middle until he hits the cymbal. And sometimes it is if they don't play in tune.. or is misses the tune.

The fullrange/midrange section is nice but misses the ...how do i say that.... involvement/drawn to effect... (my philips AD9710 (no filter) in the other speaker on the picture does has this effect on me.

Again thanks and I hope that what I wrote is a bit clear..
 
Philips AD12100m

Hello Xerxes75
Your speakers and cross-over look similar to open baffles from the Lampizator site
I have been using vintage fullrange drivers on open baffles for years now and i like them alot Also started with Lampizator clones and missed some highs and lows
You could use the AD12100m8 as fullranges (no filter) in your speakers and
add a helper tweeter with single cap (1.5uf to 2.2uf) to assist the highs Look for same 93db eff.
Similar you can add the AD12100w8 in the same set-up as a helper woofer low pass crossed at (80hz to 100hz)
Myself, i ended up with a Visaton Nobox open baffle design 52cm wide, 122cm high and the following drivers
Philips AD12202m4 fullrange
Swans RT2-C ribbon tweeters with single cap 2.2uf
Emminence Alpha 15A with DSP module low pass at 90hz
End of trip Nothing more to be desired
Succes and enjoy
 

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I was also wondering about the tweeter, It does take some getting used to in this position... But if the sound is right!...
I am jealous of your AD12202....I had the pleasure of hearing them, they played very beautiful. The eminence is wish to use in the future on an total (big) OB.

And fine tunning by ear....that's an art high on my wish list.
 
AD12100m8

Hello Xerxes75
Thanks
I think you can get good results with the drivers you have
Just try the fullrange set-up with helper tweeter and woofer i s o a 3-way crossover and if possible get a separate amp for bass
These vintage Philips drivers are fantastic
Good luck
Enjoy
 
Hi, I think that you should accept the fact that those speakers were made to fulfill
some duties, which they did and do accordingly to their electromechanic characteristics.
One thing you can do is to change one kind of characteristic, the easiest one is to add mass to the cone. That may need some stiffening at the spider....or why don't you ask yourself how much displacement of air is needed in your room to accomplish the sense of full & rich bass that you seek...
For the question about the complex load, see the replies in ...http://www.diyaudio.com/forums/multi-way/250784-would-i-right-thinking.html
 
AD12100m8

Hello Xerxes75
Please do not be afraid to put the Philips fullrange Just listen to it
Fullrange will add the body you are looking for
Later following taste you can add the tweeter with single cap 1.5uf to 2.2uf
and the woofer with the same cross-over you have already
If you want to go active Look for a second hand sub plate amp on the net
Tweeter will add some highs and woofer will help in he lowest octaves
There will be no need to change enclosure
Good luck
Enjoy
Ronny
 
Well listening to only the full range driver for a while, and reading the replies and other threads in the meanwhile.

I want to give the full range driver a special place in it's own (shiny) baffle with the tweeter (maybe a different one) placed off centre and keep the bass driver in it's one enclosure but placed more to the background. In the near future I will give the bass it's own amplifier(s).

So I came up a new plan... The new baffle is 600 mm wide and 1280mm tall (I am thinking on how to keep the baffle upright).
In the attachment you can see the old on the left and the new on the idea on the right.

Maybe this is just a stupid idea so I like to hear your ideas.
 

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Progress

It has been a while but there is some... progress.

As said I now run the Philips AD12100M/8 fullrange together with the Philips AD160T/8. Unfortunately I could not get the more sensitive Vifa drivers.

The progress is that I reanimated my (burned out)LM3886 amp and use it to power the fullrange and tweeter. For the moment this amp is mounted on a piece of wood..as I am thinking on a diy cabinet.

So now I have the LM4780 amp for the woofer section. I would prefer some other amps but that is something for the future (in the meanwhile I am experimenting with the capacitance on the LM4780 to improve the bass response. (suggestions as mentioned in the thread about this).

This new setup sounds pretty good but I think there is plenty of room for improvement.

Since I did not get the Vifa tweeter I am open for suggestions.. The Swans mentioned by Chips666 look interesting (I love the look) but buying them new is a bit out of budget.

I am going to experiment with the placement of the tweeters. Offset and lower would help to lower the design with a few centimeters but that's only if the sound improves. I am doing some reading on this.
 
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