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.

 

The coax compression is the tweeter????.
I also found putting the speakers on a dense 9" tall block helps the bass a lot. And it lifts the tweeter/coax more to ear level.

Did you get better cables from ceossover to drivers. Also, that crossover can't touch the frame. Its a disaster when it does. A horrible smear from the vibration.

 

Yes the compression driver in the Coax (Baymer).

I have 2 bass drivers below the coax, so the height is just right.

I am looking at copper ribbon cables. I have asked for a price from Verrastar.

I have the crossover on top of a thick granite sheet, on top of the speaker base. It is good, little vibration. I also glued many of the caps and resistors in place as you find in many subs. I can't have the crossovers outside the frames as no room left.

 

So I added a Jupiter Copper in oil 2.2uF cap on the comp driver / HF circuit. First 2 days, oh dear it's sound dull and flat. Next 2 days it is opening up and the magic is happening. Lots more burn in, but we got over the panic stage.

This as I suspected this is a very nice tweak. I am very sensitive to treble grain, especially in digital. The Jupiter cap has the same detail and resolution of the Mundorf gold/silver cap, but is much more organic and realistic. Female vocals for examples are way better. At 240 euros for 2 caps not cheap, but the whole speaker has got an upgrade.



The Jupiter cap is the red/brown cap mounted vertically. It is also bypassed with a silver Duelund 0.01uF mounted under the board. I also bypassed the other 3 Mundorf caps with tiny 0.01uF Mundorf Gold/Silvers.

So I think the crossover is done, maxed out and I am very happy with the sound. In December I will look at changing the speaker wiring. It is Van-den-Hull as supplied. I am looking at buying silver/copper bare wires, and making my own loom up. I considered Verrastar foils, but probably can't afford them.

Onward.....

 

I ordered the silver plated copper wires for the hook up cables. I will do the compression driver and mid driver first.

I am going to use 0.4mm, 0.6mm, 0.8mm and 1.0mm wires, probably 3 of each, then shrink wrap the twisted bundles, cotton rope and some cotton bands, then tinned braid over the 2 channels, then pvc braided jacket. I found a video on how to assemble then on YouTube.

I'll report back in a few weeks, once I get all the bits and build them.

 

Change the 6.8mh inductor to air core.

 

Hi Rex. It is a 12.8 inductor. I would but I can't fit an air core as no room left. TBH to bass speed and detail I am getting now with the 3 caps on the inductor, it is superb.

 

Odd. Why would yours be different than mine? Mine is hanging on a wooden peg below the crossover.

What caps go to the Coax. I like the Jupiter copper beeswax.

What do you sense getting from the bypass caps.

 

Odd. Why would yours be different than mine? Mine is hanging on a wooden peg below the crossover.

What caps go to the Coax. I like the Jupiter copper beeswax.

What do you sense getting from the bypass caps.

Legolas has the Quintet Rex… the Trio runs with a lower inductance because of the different setup with the impedance of the extra woofers running in the quintet.

I find the Trio and the Quintet display quite different characteristics and strengths that come out in the varying ways they respond to different music… I like both.

 

Owe. I missed that. Makes sense.

I'm still thinking of biamping. I would start by using an active crossover. I would have my preamp signal go into the active crossover. On the high side, I will pass full frequency through the active and into the high side of my stock crossover. The coax will continue to be shaped by this.
On the woofer side I will try and blend to the high side and run the bass amp from the active filters.

I am thinking of doing this to limit what my preamp sees as loads. It may all fail. Who knows till you try.

 

Got these beasts coming in in a week. To replace the Ferrite rod inductors. These are BIG AirCores. To get the DCR down you have to use a lot of thick copper!



Solen 10AWG 12mH 0.47 DCR. 175 mmm diameter, 50mm high.


Here you can see the stock Inductor above the cable posts. It is a 12mH 0.39 DCR Inductor. I will need to point the new Aircore outboard bottom left on a new board. Lets see how it sounds, I'll report back.

I also finished my DIY wiring loom for the Coax, took a while to make. I will see how that sounds v stock wires.

 

Got these beasts coming in in a week. To replace the Ferrite rod inductors. These are BIG AirCores. To get the DCR down you have to use a lot of thick copper!

View attachment 142008

Solen 10AWG 12mH 0.47 DCR. 175 mmm diameter, 50mm high.

View attachment 142011
Here you can see the stock Inductor above the cable posts. It is a 12mH 0.39 DCR Inductor. I will need to point the new Aircore outboard bottom left on a new board. Lets see how it sounds, I'll report back.

I also finished my DIY wiring loom for the Coax, took a while to make. I will see how that sounds v stock wires.

Would love to get your thoughts on how the Solen inductors change things up for you when they are settled in. I have been looking at either these or going with the 8 awg in the Solens.

 

Fitted my 2 x DIY cables for the Coax unit today. Note I used some UK plug earth posts for the crossover tabs. The cables are quite stiff, but workable. I removed the lower speaker panel to gain access. The cables are copper silver plated, multi strand, with cotton sleeve inners, and a copper shield which I will ground to the frame. The wires ended summing to 10AWG per + and - legs. I will run them in and keep the pot connected on RTs pad till I know the right resisistor value to fit for the compression driver. It is set at 6 Ohms, v 8.2 Ohms stock, at the moment.

Will report back how the cables sound. The Solen Inductor is due in the next few days.

 

Ha Ha it is HUUUUGE!. 15 kilos each.

I can't hear any bass gain loss, the difference in DCR is 0.39 Ohms v 0.47 Ohms. So that is good. I'll run them in and report back in a couple of weeks. So far so good.

Thinking I am maxed out now. I suppose the 3 Mundorf caps left, one pn the treble circuit, 2 on the mids. I changed the critical one to a nice Jupiter copper in oil, made a nice increase in transparency and more creamy.

 

View attachment 143121

Ha Ha it is HUUUUGE!. 15 kilos each.

I can't hear any bass gain loss, the difference in DCR is 0.39 Ohms v 0.47 Ohms. So that is good. I'll run them in and report back in a couple of weeks. So far so good.

Thinking I am maxed out now. I suppose the 3 Mundorf caps left, one pn the treble circuit, 2 on the mids. I changed the critical one to a nice Jupiter copper in oil, made a nice increase in transparency and more creamy.

That is awesome!… and it doubles as mass damping as well! How cool.

Congratulations. Am looking forwards to how it all works out for you.

 

Hi @Legolas,

I have been following your journey on this forum and align with your methodology on upgrading crossover parts but not adjusting the values (too much). I have the PAP trio 15's Coax & ordered some Pathaudio resistors to swap out for the Mundorfs and am awaiting their arrival. It appears they have a third ground wire... Did you encounter this as well and if so where did you ground them on the board?

Very much looking forward to hearing your feedback on the inductor swap.

Thx for sharing!

 

Some early findings on the big aircore.

The bass is simply superb, It is so fast, energetic and detailed. One the same bass heavy music, for example: Massive Attack Mezzanine, there is no holding the note, boom or overhang. I understand what they mean with Hysterisis distortion in a ferrite inductor. IMO this upgrade is all worth the cost, and I had to replace a huge 12mH unit, smaller ones will be cheaper.

I will report back later as things bed in again. What a speaker the PAP Quintet15 is, a bargain for this level of performance. These tweaks has shown me how important parts count are, and how there is more to get out of the same speaker. TBH the crossover as stock is built by Mundorf, and puts many speaker crossovers I have seen to shame.

 

Some early findings on the big aircore.

The bass is simply superb, It is so fast, energetic and detailed. One the same bass heavy music, for example: Massive Attack Mezzanine, there is no holding the note, boom or overhang. I understand what they mean with Hysterisis distortion in a ferrite inductor. IMO this upgrade is all worth the cost, and I had to replace a huge 12mH unit, smaller ones will be cheaper.

I will report back later as things bed in again. What a speaker the PAP Quintet15 is, a bargain for this level of performance. These tweaks has shown me how important parts count are, and how there is more to get out of the same speaker. TBH the crossover as stock is built by Mundorf, and puts many speaker crossovers I have seen to shame.

That’s really great to hear Legolas… I was watching a video discussion with custom horn speaker designer Troy Crowe on his blog… as a very experienced crossover designer he mentions the differences that he found by going bigger gauge with better air core inductors… and he notes it can a more observable and potentially beneficial improvement than upgrading caps.

He also mentioned the positives if you can also get a bit lower dcr. While I expect everything is context specific and just upgrading to a better spec part isn’t always going to be a summative win but it’s great feedback that the Solen 10awg are proving very positive… look forwards to any more updates when you feel they are more settled in… thanks again for your exploration.

 

@Legolas
I looked at the Jupiter caps you told me about. They seem to be about $450 each. x 2. I do like the Jupiter copper bees wax sound.

The stock crossover is well done. I too changed the inductor on mine to solid wire, air core 14 AWG. I big change for the better. Only wires from the crossover to the driver had as much impact.

 

@Legolas
I looked at the Jupiter caps you told me about. They seem to be about $450 each. x 2. I do like the Jupiter copper bees wax sound.

The stock crossover is well done. I too changed the inductor on mine to solid wire, air core 14 AWG. I big change for the better. Only wires from the crossover to the driver had as much impact.

The are the new I bought:

PH8001-1225J: 2.2uF 100Vdc Jupiter Copper Foil, Paper & Wax Capacitor | HIFICollective

PH8001-1225J: 2.2uF 100Vdc Jupiter Copper Foil, Paper & Wax Capacitor

www.hificollective.co.uk

 

That’s really great to hear Legolas… I was watching a video discussion with custom horn speaker designer Troy Crowe on his blog… as a very experienced crossover designer he mentions the differences that he found by going bigger gauge with better air core inductors… and he notes it can a more observable and potentially beneficial improvement than upgrading caps.

He also mentioned the positives if you can also get a bit lower dcr. While I expect everything is context specific and just upgrading to a better spec part isn’t always going to be a summative win but it’s great feedback that the Solen 10awg are proving very positive… look forwards to any more updates when you feel they are more settled in… thanks again for your exploration.

Yes I got the biggest Aircore I could find just to get the DCR down to 0.467 ohms. The stock ferrite inductor is 0.39 Ohms. I don't hear a drop I bass volume. It is only 0.08 Ohms difference, so not a problem.

The caps change the mids and table, the inductor the bass, probably to a similar level of improvement TBH.