Pretty Persuasions - InDIY Coax Build Thread

[Paul K.]

Right on.
Paul

To clarify, they matter if you can hear a difference, and that’s for each person to decide.

[Wolf]

He makes most feel this way. You know how many pair he built last year, right?
Later,
Wolf

[1100xxben]

Javad, you're making me feel like a slacker. I finally have all my drivers ordered and the last shipment should arrive today. It's time to finish the box design and start making some sawdust.

Those look great. I love the way the grain turned out with that finish, and I'm still impressed that those are a bent, "solid" piece of wood!

[craigk]

Great idea on the jumpers for the binding post. I will use this.

[JavadS]

Before final assembly I played around with the crossover one last time (for now lols), my one sticking point after extensive listening was a lack of detail and top end response, I rolled off the top of the tweeter to deal with the hump at 2800 but this rolled off 5k more than I wanted to, so I experimented with some inductors across R2 and a .025mh brought up response above 5k nicely and brought that air and detail back that I felt was missing







I heat test all my crossovers and found the temp of the mid lpad resistors was getting to about 105F after extended play at peak volume, some heat sinks brought that right down to a max of 80F (in a 70F room) which I was very comfortable with. Heat sinks attached with heat sink glue



Crossover boards installed with stapled adhesive Velcro and a single screw to secure it



Internal wires for one enclosure, each binding post connects separately to the crossover board circuit for that driver.



Woofer terminals



Black 3M strip calk to seal wires passing into the mid enclosure, works and seals very well and is serviceable if needed



Wiring buttoned up









Binding post holes



Installed



Solid 3/16” 99.999% copper rod, cut to 2.75” length and ends rounded











Ready for gold plating



Gold plated





Installed



All buttoned up and lots of listening to do! Will do a nice photo shoot and post pics next week



Thanks!
Javad

[JavadS]

Sorry for the length between posts, been getting a lot done!

Here’'s where things start, enclosures stripped back down and ready to finish. I did a final pass with 220 to perfectly smooth things out and get a fresh layer of wood. Glad I did too as in the month or so since the last glue up a few seams crept settling a little (like maybe 1/100th” and I got a chance to smooth them back out.

I’'ve never used it but been hearing good things about Rubio Monocoat. It’s an oil finish with a catalizer that reacts with the oil and creates a hard finish that bonds at a molecular level to the wood fibers. It initially came out for hardwood floors which gave me confidence to use it on speakers, and I was looking for a matte finish like with Danish oil but something a little more advanced and durable.




You simply mix the two and wipe it on sparingly (no need to flood the surface), then wipe it lightly 3-5 minutes later, then let it cure for 3 days, super easy and idiot proof. And man does that grain pop!
















After curing for 4 days I began final assembly, more to come!

Javad

[JavadS]

Javad -- By all means you are welcome. Well deserved. I would like to replicate part of this project with the curved baffles/sides and out of curiosity (and forgive me if you spelled it out somewhere), what is the width of your kerf on your blade and the exact blade you used on your table saw (it appears to be an ATB)? I am running a Forrest 10" Duraline Hi-A/T .100" blade on my table saw. Also what is the spacing between the cuts to get the radius on your box edges?

I'm using a Diablo thin kerf blade, the width is .098", but you can use any width blade successfully, you'll just space your cuts differently though you'll want to avoid a very thick blade if you can.

I'd like to compliment your method of joining the two boards together. We exclusively use biscuit construction whenever possible. It makes for a cleaner/stronger bond IME.

Yes love biscuits and they're very forgiving on positioning but result in a very tight and level joint.

Anyhow, I'll probably think of some other questions and hopefully you don't mind me picking your brain. I am relatively new to these forums.
Chris

Happy to help anyway I can, don't hesitate to ask away!

Javad

[STIchris722]

Thank you for the kind words! The bracing serves two purposes, one yes it's structural, as the kerfed front and sides have a lot of spring to them, and are in of themselves not very structurally sound, the braces act as strengthening ribs, much like the ribs in a wing, to give the assembly structural rigidity and keep it dimensionally stable. Two, the braces work to change the acoustic signature of the enclosure, as panels are broken up into smaller irregular shapes (not square), the amplitude at which they resonate decreases, and the frequency increases, to a point where it isn't audible. W/o these braces, this enclosure would be very loud and actually affect the frequency resonse of the speaker (read you would hear the cabinet resonating), and as that's not something we can control like we can a speaker driver, we want to remove that dynamic from the acoustic output of the speaker as a whole.

Thanks!
Javad

Javad -- By all means you are welcome. Well deserved. I would like to replicate part of this project with the curved baffles/sides and out of curiosity (and forgive me if you spelled it out somewhere), what is the width of your kerf on your blade and the exact blade you used on your table saw (it appears to be an ATB)? I am running a Forrest 10" Duraline Hi-A/T .100" blade on my table saw. Also what is the spacing between the cuts to get the radius on your box edges?

I'd like to compliment your method of joining the two boards together. We exclusively use biscuit construction whenever possible. It makes for a cleaner/stronger bond IME.

Anyhow, I'll probably think of some other questions and hopefully you don't mind me picking your brain. I am relatively new to these forums.
Chris

[Paul K.]

Here's a short and sweet addition to what Javad explained about cabinet bracing. You want the speaker system to really sing, but you don't want the cabinet to be singing along with the music.
Paul

[JavadS]

As a cabinet makers son and apprentice, I have much appreciation for the artwork you have demonstrated here. Absolutely brilliant!

I have one question and it's only out of ignorance. All of the bracing on the inside of that cabinet (appears to be 3/4"), what is the purpose of that? Aside from the obvious, does the box really expand that much to require all that bracing? Again I really don't know, just curious more than anything. Props again!

Thank you for the kind words! The bracing serves two purposes, one yes it's structural, as the kerfed front and sides have a lot of spring to them, and are in of themselves not very structurally sound, the braces act as strengthening ribs, much like the ribs in a wing, to give the assembly structural rigidity and keep it dimensionally stable. Two, the braces work to change the acoustic signature of the enclosure, as panels are broken up into smaller irregular shapes (not square), the amplitude at which they resonate decreases, and the frequency increases, to a point where it isn't audible. W/o these braces, this enclosure would be very loud and actually affect the frequency resonse of the speaker (read you would hear the cabinet resonating), and as that's not something we can control like we can a speaker driver, we want to remove that dynamic from the acoustic output of the speaker as a whole.

Thanks!
Javad

[STIchris722]

As a cabinet makers son and apprentice, I have much appreciation for the artwork you have demonstrated here. Absolutely brilliant!

I have one question and it's only out of ignorance. All of the bracing on the inside of that cabinet (appears to be 3/4"), what is the purpose of that? Aside from the obvious, does the box really expand that much to require all that bracing? Again I really don't know, just curious more than anything. Props again!

[JavadS]

If you're interested, as long as two air core coils have at least 2" distance between their perimeters, mutual inductance and voltage crosstalk are essentially inconsequential even with the coils oriented the same. I started to reply to Skatz about his comment and thought your two coils were adequately spaced, but I couldn't tell for sure. Paul

Thanks Paul! I actually hooked up my Dats and WT2 a while ago and measured the effect to other inductors, powered voice coils and magnets, I also found once past 2” any measurable effect was minimal. By far the worst thing I measured was two inductors stacked concentrically on top of each other, the effect was quite measurable then, as much is a 50% change in value.

[Paul K.]

If you're interested, as long as two air core coils have at least 2" distance between their perimeters, mutual inductance and voltage crosstalk are essentially inconsequential even with the coils oriented the same. I started to reply to Skatz about his comment and thought your two coils were adequately spaced, but I couldn't tell for sure.
Paul

Thanks for the comment, yea I can they are about 4" apart and the response of this crossover is identical regardless of how I orient the coils, I did test it. Thanks!

[JavadS]

Great thread ! As a wood worker of 35 years I can appreciate the skill.. The knowledge of the x overs and such is always cool

Thanks I appreciate the comment, and thank you for following along!

Javad

[JavadS]

Javad, is this how your company builds high performance car parts ? Ben's comments matter because somehow people think that parallel parts in a crossover don't contribute to the sound. Everything in the circuit contributes. Your answer is a little arrogant.

Craig your response is a little inflammatory, but you know I love you so I won't take the bait =) My point was, IF you can hear the difference between a electrolytic cap or a MKP or a foil cap or a $5 cap or a $100 cap, it only matters if you hear the difference. That's not arrogant, that's matter of fact, it's in agreement with what Ben said and simply a clarification, no need to demonize it.

I'd like to politely ask we keep the thread on topic, really not looking to get into a superficial back and forth about semantics, I can safely say I am in agreement with what Ben said and stand behind my clarification.

Thanks,
Javad