JBL 804 vs TangBand 740P

[N.Webber]

This is it:



The X-over as well as the level control and A/B switch will be mounted opposite to the amp. inside the other half of the rack.

[Gregory East]

So measuring mic goes straight into pc running trueRTA? That's free software iirc! For comparing cabs any old mic that can hear 40hz would be ok methinks.

[N.Webber]

So measuring mic goes straight into pc running trueRTA? That's free software iirc! For comparing cabs any old mic that can hear 40hz would be ok methinks.

Well not really…

the basic (free) TrueRTA is limited to 2/3 octave resolution, this will yield only a very general plot/view of the response and will not be detailed enough, especially in the first two octaves. The paid version offers up to 1/24 octave…

'any old microphone' will not do. It will probably have directional pattern (cardioid) to some degree and also may have a tailored response built in. For correct measurement you will need a dedicated measurement microphone. These are omni-directional and have flat response throughout their working range.

And last, going directly into a PC's audio input means relaying on its generally crappy A/D converter. A much better way is to use an external sound card with a 'real' microphone input (XLR) and preamp. It will also supply the phantom power for the mic.

I am using the DBX RTA-M microphone and M-Audio's Fire-wire Solo sound card.

[Ryan A]

What panel width did you use on your AT's?

Overall width is 400mm, so the panels are 376mm (about 14-3/4")

Also, subjectively speaking, do both sound exactly the same to your ears or does one sound louder or have different tonal characteristics than the other?

As much as I tried to find a point of difference between the two, I just couldn't.
I kept switching between the cabs while listening to various pieces of music and simply couldn't notice any difference between the JBL and the TB.
In terms of level/sensitivity, response, or tonality both cabs appeared to sound identical.

Next week I hope to manage the comparison/test in my wife's car…

Thanks for the information. Since both drivers perform nearly identical, I suppose the only thing that could be different is max output, based on the RMS power rating and Vd of different drivers.

[N.Webber]

OK, I'm almost there. The amp. rack is ready and tested:



I hope to manage tommorow the comparison test in the car. On Friday I am going to demo the AT at a meeting of a local car audio group.
It will be interesting to see their reaction to this 8" + 150w amp. setup...

[Bill Fitzmaurice]

On Friday I am going to demo the AT at a meeting of a local car audio group.
It will be interesting to see their reaction to this 8" + 150w amp. setup...

Tell them to be sure to wear brown pants.

[Drey Chennells]

I like the double sided access on your rack, very nice. I keep a TAT19/10" in our shopbus as the standard rig and it's really impressive, great for business. When we pick up at the lumberyard, vw show, etc. it's shock and awe. The look on the faces of these guys with dual 12 systems and 1k+ watt amps is priceless when they register what we're packing.

[Radian]

It will be interesting to see their reaction to this 8" + 150w amp. setup...

I predict only a smattering of interest. A few might get it, but most won't know half of what you're doing or talking about. If it doesn't move, sparkle, or they can't see their own reflection in it.. Only talking from experience here.

OTOH...it's a great idea for promoting sound quality and demonstrating your product in a very effective manner!

[N.Webber]

Tell them to be sure to wear brown pants

Unless they want to sit in the car, then its diapers...

I predict only a smattering of interest. A few might get it, but most won't know half of what you're doing or talking about. If it doesn't move, sparkle, or they can't see their own reflection in it..

Yep, I agree, I know exactly what I'm up against…
I am promoting this demo for some time on this group's forum and one member was drooling over the idea of a Plexiglas AT…
I replied with a picture of a transparent Sketch-Up view, but come to think of it, this could actually be one hell of a demo AT

[Radian]

but come to think of it, this could actually be one hell of a demo AT

I've contemplated this idea too...as a "Can I actually do it?" type project. A test of skills...so to speak.

A flame polished, bonded-acrylic AT would make for one incredibly sexy demo piece, but it's so unforgiving to work with.

Square and true take on a whole 'nother meaning when working with solvent instead of PL.

[bassmonster]

You could use clear bathroom silicone sealant but I don't think that would be strong enough on its own. Perhaps use 1" Plexiglass for the outer panels and for strength recess the other panels by routing a 1/2" deep "channel" for the panels to be placed and installed?



It would be heavy, and there's still the issue of adhesives.

[cheapbasslovin]

Maybe just do one side in plexiglass.

You can still see inside everything, but there are the problems of bonding plastic to wood and keeping the inside of your build clean .

[BassMe]

Now that would be a cool lookin sub though!

Could you place gasket tape across the tops of all the folds in the horn and then use a HEAP of screws to screw the plexiglass onto it?

[88h88]

See now I'm imagining an aussie voice saying "heaps screws" and I'm laughing to myself.

But yeah, I don't see why not. It'd probably add about 20kg due to how many I'd use 'just in case'.

[BassMe]

Now I want to build my TT's as coffee tables like that lol. Wonder how much the plexiglass would cost. And the LED's to go in it.