Pure Audio Project upgrades and tweaks

Starting this thread to discuss Pure Audio Project open baffle speakers, upgrades and tweaks. @Kingrex - if you have had both the horns and Coax10, I would be interested in hearing how they compare. And I copied your earlier post below.

What cables upgrades did you use? And can you share a picture of where you located the crossover? Is it attached to something else, or sitting on the floor? I was wondering about the height of the midrange/tweeter and if I should rake the front up. My system will be the Trio15 Coax10, Playback Designs MPS-8 source and Pass Int-25 amp. I'm still waiting for my walnut baffles to ship from RJ Millworkers.

You have to get the updated speaker cables. Its critical.

And , you have to separate the crossover from the frame. Again critical.

If the crossover is touching the frame, the music is very smeared from the intense physical vibration.

If you use stock, instead of upgraded cables, you loose life, air and bass. Less coherent.

The speaker is very good with these tweeks. You don't need to futz with any caps or reaistors with the Coax crossover.

You need to be patient. They take 500 hours like any speaker to break in. 2000 or a year to really be there. I actually put my coax in the basement connected to a class D amp and laptop for week and let it rip sitting on the floor. I would go dowm 3 or 4 times a day to switxh the album and volume.

Also, mine sit on a 9 inch tall very heavy block of wood that sits on fiberglass insulation. A rug would also work. Massive improvement in bass. Just shocking. And, it raises the center of the coax much closer to ear height. Otherwise its too low and like sitting in a balcony.

The fabric over the top keeps the sun from striking the driver. That is all its for.

 

You can change all parts at beyma coax its professionell driver , you need only a other 1" diaphargma.
If you want to try the Fostex, remove the diaphragm and you will have only a 10" driver.
1" diaphragms are available from many manufacturers in all imaginable materials. Aluminum, berylium, titanium, polydyne, etc. Only the terminals must fit in the pressure chamber lid.

1" diaphragma horn driver - Google Search

View attachment 155087

I use 1" horndriver without the lid , then it works as dipole. Advantage reduces distortion that occurs in the pressure chamberView attachment 155088

The image of your driver seems to be a CD for the tweeter that has its own magnet.
I sort of wondered what would be the issue of having a second magnet. As long as the bolt holes fit. I guess a spacer could be made to accommodate holes. But, the diaphragm is going to be further back. Possibly inducing timing issues???

What if I used that Fostex and used heavy duty double sided tape to mount it to the back of the 10" driver. I would of course find some additional way to secure it.

If I just changed the diaphragm, would I get much of a performance gain??? Or just another sound. Everything else would remain the same. The magnet, wiring etc???

I need my new microphone before I do anything else. I want accurate measurements.

 

Looking at this graph the graph is very uneven in many places.
the 8 to 10k might be a resonant peak
the fall off does seem fast.
But a typical room sweep does not always need to be flat.
one thing to start is on axis 3 feet back to confirm the output of the driver

Could be Al. I wasn't able to find my pile or resistors yesterday. They are buried in the work. I have another place to look. I think it has always fallen off. But the peak could be the room. I can try another sweep in front of the speaker and mute one channel. See what happens. I don't have them toed in much. Maybe 5*. But that may do something to create a peak.

I am ok with the roughtness. What I really wanted was a gentle slope with a high on the bass and slight down on the treble. At least I want to try that.

 

The image of your driver seems to be a CD for the tweeter that has its own magnet.
I sort of wondered what would be the issue of having a second magnet. As long as the bolt holes fit. I guess a spacer could be made to accommodate holes. But, the diaphragm is going to be further back. Possibly inducing timing issues???

Beyma have two models of a 10" coax driver diffrent year of build. No timing issuses the way is too small

What if I used that Fostex and used heavy duty double sided tape to mount it to the back of the 10" driver. I would of course find some additional way to secure it.

Bad idea, you're robbing the Fostex of all its strength, resolution, and beam angle. Drill a hole in the coax baffle and push it through flush. Make the hole a bit larger for a gasket around the Fostex.

If I just changed the diaphragm, would I get much of a performance gain??? Or just another sound. Everything else would remain the same. The magnet, wiring etc???

Different materials can make your ear feel like it is playing louder

I need my new microphone before I do anything else. I want accurate measurements.

Best idea today correct measurement 1m distance height of the coax
I've tried all sorts of drivers in Open Baffle last 8 years , but no standard driver has made me completely happy in the long run. All my drivers have been modified, for example, drilling holes in the magnet to change the TS parameter or QTS value.

 

I was watching a video on Von Schwikert speakers. They use multiple tweeters. I may try to pull down the hump, then add a second dipole tweeter.

 

I got the Dayton imm-6c microphone. Looks like the hump at 8k was the internal phone microphone. Kind of amazing how much a microphone impacts he chart.

One image is the pink noise. The other is pink noise with the CD tweeter disconnected.

 

I got the Dayton imm-6c microphone. Looks like the hump at 8k was the internal phone microphone. Kind of amazing how much a microphone impacts he chart.

One image is the pink noise. The other is pink noise with the CD tweeter disconnected.

Take a measurement of the 10" without tweeter directly coupled to the tube amp. I'm interested in what frequency response it has without crossover in baffle 1m distance.

 

Take a measurement of the 10" without tweeter directly coupled to the tube amp. I'm interested in what frequency response it has without crossover in baffle 1m distance.

Are you asking me to direct couple the mid range to the amplifier?

 

Are you asking me to direct couple the mid range to the amplifier?

Yes, you have a wideband driver thats no need a xover will probably sound better without a xover you must only xover point for horntweeter higher.

 

The midrange does need to blend with the woofers. At this point in time, I am not looking to scrap the whole speaker crossover. I don't have a second Blade amplifier to run the subs. And I don't want to vertically integrate with a tube and a SS amp. As I noted earlier, Ze'ev has tried to run the 10 inch midrange, wideband and said it did not have enough of whatever he wanted to hear in a open baffle setting.

I am going to focus on improving the top end while trying to retain the PAP crossover.

I am not saying your design might not perform better. I get the concept that a crossover has drawbacks. I just don't want to open the entire can of worms and struggle through designing my own open baffle speaker at this time. If I did go that route, I would more than likely move to a wideband horn and ditch the open baffle all together.

 

I used NoRez for one side of the frame.

No Rez (Sheets) | GR-Research

gr-research.com

I did try with both sides covered with NoRez and found I preferred only one side covered. If it wasn’t such a chore to reapply and remove the NoRez I might try again now that I’ve changed a few things. I’m also so happy with the sound I’m getting I don’t want to mess with anything major. Only thing that is changing in the near future is I’m getting some custom power supplies from Zayin audio for the field coils. After that I don’t want to mess with anything.

Let us know how the cork between the joints works. I used an impact driver when I put my frame together so it’s extremely tight.

Hello everyone
I have tested cork insulation, well when I say tested........
I had reassembled the speaker on which I had applied the insulator, all I had to do was connect the cables to the speakers.
Before reconnecting them all, I wanted to test the vibrations of the speaker with the cork insulator and the speaker without the cork insulator.
The speaker with the insulator had a more matt, less metallic sound.
I thought that was a very good start.
But when I compared the vibrations produced by a simple finger tap on the metal frame and did the same finger tap on the other frame, I immediately realized I was going in the wrong direction.
there was more vibration on the frame.
So I took it all off and put it back where it came from, without trying to listen to it.
I'm just going to test by putting small sandbags on the base and we'll see.
I'm going to concentrate on the cables feeding the speakers.
A lot of work for a negative result.
I didn't waste any more time.

 

Hello everyone
I have tested cork insulation, well when I say tested........
I had reassembled the speaker on which I had applied the insulator, all I had to do was connect the cables to the speakers.
Before reconnecting them all, I wanted to test the vibrations of the speaker with the cork insulator and the speaker without the cork insulator.
The speaker with the insulator had a more matt, less metallic sound.
I thought that was a very good start.
But when I compared the vibrations produced by a simple finger tap on the metal frame and did the same finger tap on the other frame, I immediately realized I was going in the wrong direction.
there was more vibration on the frame.
So I took it all off and put it back where it came from, without trying to listen to it.
I'm just going to test by putting small sandbags on the base and we'll see.
I'm going to concentrate on the cables feeding the speakers.
A lot of work for a negative result.
I didn't waste any more time.

 

Hello everyone
I have tested cork insulation, well when I say tested........
I had reassembled the speaker on which I had applied the insulator, all I had to do was connect the cables to the speakers.
Before reconnecting them all, I wanted to test the vibrations of the speaker with the cork insulator and the speaker without the cork insulator.
The speaker with the insulator had a more matt, less metallic sound.
I thought that was a very good start.
But when I compared the vibrations produced by a simple finger tap on the metal frame and did the same finger tap on the other frame, I immediately realized I was going in the wrong direction.
there was more vibration on the frame.
So I took it all off and put it back where it came from, without trying to listen to it.
I'm just going to test by putting small sandbags on the base and we'll see.
I'm going to concentrate on the cables feeding the speakers.
A lot of work for a negative result.
I didn't waste any more time.

What about Sorbothane or thicker rubber?

 

Self-adhesive anti-noise mat from the automotive sector. Cut to size, clean the surface, and you're done. Only a hot air gun will help to remove it.

2 qm Alubutyl 50x400 cm Dämmmatte selbstklebend Anti Dröhn Matte Fahrzeugdämmung : Amazon.de: Elektronik & Foto

2 qm Alubutyl 50x400 cm Dämmmatte selbstklebend Anti Dröhn Matte Fahrzeugdämmung : Amazon.de: Elektronik & Foto

www.amazon.de

 

Self-adhesive anti-noise mat from the automotive sector. Cut to size, clean the surface, and you're done. Only a hot air gun will help to remove it.

2 qm Alubutyl 50x400 cm Dämmmatte selbstklebend Anti Dröhn Matte Fahrzeugdämmung : Amazon.de: Elektronik & Foto

2 qm Alubutyl 50x400 cm Dämmmatte selbstklebend Anti Dröhn Matte Fahrzeugdämmung : Amazon.de: Elektronik & Foto

www.amazon.de

Hello
Sorry it took me a while to reply.
I did various tests and then the holidays came around.
Here are the photos of what I did with the cork that was supposed to absorb the vibrations.
In the end I didn't test more because when I finished the first speaker, I tapped lightly on the frame,
It vibrated slightly more with a sound that was matt.
So I immediately removed the cork.
It was very difficult to remove because it was self-adhesive and stuck really well.
However, I did change the stands on my speakers.
I used to have Inovaudio spikes and counter spikes.
I tested the hifystay feet that I'd had for a long time but which I didn't use under the speakers.
I'm glad I did, I've gained a bit more air in the soundstage.
Some time ago I had moved my crossover.
So I made a provisional cut just to see if there was any point in doing it.
I'd like to thank you for this advice, because I've gained in clarity by having moved the filter.
I'm going to try putting a small bag of sand on the base of the speaker, it's quite possible that doing this will help.
That should absorb the vibrations. To be tested.
Later I plan to replace some of the crossover components, particularly the large coil with the exposed copper wire.
Then I also need to replace the speaker wires.
I'm going to do this gradually as it represents a budget.