JBL 804 vs TangBand 740P

[shawn_g]

Very interesting test! Nice looking cabs as well.

[bassmonster]

I like the real world comparisons.

[Gregory East]

Peak ratings show that when the juice really gets flowing, the driver will be up to the task, both thermally and mechanically.

Not really. Peak ratings are advertising crap. At one point the FTC banned the use of anything but RMS. Then the Reagan administration came in and put the foxes in charge of the hen houses and that was the end of that. Peak ratings are meaningless and should be ignored. And mechanical limits tend to be lower than RMS.

I missed this before.

For a couple of compliant non plan AT drivers you have given a limit voltage working out to be the rated RMS power at nominal driver impedance. I have taken this as a trend and reported it to a few enquiries about this or that without you raising a comment so I wonder if you might confirm the notion of AT being an exception to the general

And mechanical limits tend to be lower than RMS.

Is this the reason there is no voltage limit specified for AT?

[Ryan A]

Is this the reason there is no voltage limit specified for AT?

There's a voltage limit for all driver/box combinations...Bill was trying to explain why RMS is more important than peak. One of the reasons he thinks peak ratings are gibberish is because the mechanical limits of the driver (overexcursion, etc.) are going to happen at a lower power than even RMS, let alone peak, power. This is true at least at very low frequencies around the drivers lowest usable frequency and lower, and also when the driver is not horn loaded.

I would like to see these two AT's do a max voltage shootout! Would be interesting to see which one holds up better. Of course, I wouldn't want you to blow up your brand new drivers in the process!

Beautiful looking boxes, by the way!

[N.Webber]

I would like to see these two AT's do a max voltage shootout! Would be interesting to see which one holds up better. Of course, I wouldn't want you to burn up your brand new drivers in the process!

+1
Need to find a practical & affordable way to measure/monitor the cone movement while inside the cab...

[Bill Fitzmaurice]

Is this the reason there is no voltage limit specified for AT?

Cars don't have limiters.

[bassmonster]

Need to find a practical & affordable way to measure/monitor the cone movement while inside the cab...

Temporary acrylic or Plexiglass access panel cover?

[N.Webber]

While I'm waiting for some accessories for the car install, and as I am planning on building a set of the David floor standers,
I decided to try and simulate these with the AT toped with a small bookshelf speaker, as in the David configuration.

Like this:



The AT was lifted on top of 6" spacers and placed near the room corner.
The cabs were driven through an active 2 way x-over (crossed at about 100Hz) and separate amp. channels.

I was pleasantly surprised by the good balance and low end extension of this setup.
Apart for the earlier noted peaks, the overall response was quite smooth and very pleasant - I am tempted to say Hi Fi.
I wasn't expecting any substantial reproduction below 35Hz but it was defiantly there, down to even 25Hz!

This is the measured response of the setup + room:



Mind you, I wasn't trying to determine the maximum level of this setup, but I felt there was enough headroom to enable serious levels, if needed…

[Gregory East]

Yep, that's how BAT gets used too.

[Ryan A]

What panel width did you use on your AT's? 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? I'm curious if, and to what extent, different drivers change the overall sound. Looking forward to updates

[Radian]

I'm curious if, and to what extent, different drivers change the overall sound.

By-ear comparisons of horns using band-pass limited signals yields no subjectively useful data. I have done this with a few horn designs too, proving to myself, what Bill already states in the FAQ's section. They have no characteristic "tone".

One cab will simply play louder than another at different frequencies ( ie. differences in frequency response)...as shown in the previous graphs, but it's nice to finally get an idea by how much. The JBL is a great piece of kit, if you've want to get spendy.

Nimrod's cabs are always something to pore over.

[Ryan A]

The JBL is a great piece of kit, if you've want to get spendy.

Actually, the JBL cost less online than the TB, depending on where you shop I suppose. I got mine from the popular online auction site.

[N.Webber]

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…

[Gregory East]

What gear do you need to run the comparison test?

[N.Webber]

What gear do you need to run the comparison test?

I am currently preparing a portable 'kit' that will enable a quick and simple hookup to any car. This is intended mainly for demonstration purposes of the AT. The kit will include an input level (volume) control, a 2 way electronic crossover, a two channel amplifier (bridged for the AT) and an A/B selector switch for the output. All these components will be held together in a light and compact wooden open frame/rack, with all the inter-connections already wired up.

The idea is to be able to drop the (demo) AT into any car, hookup the rack to the car's 12v, connect the AT and the car's existing sub (if there is one), take the HF output from the rack's XO into the cars HU (thus using the car's system for the mid/high reproduction) and feeding the rack from any available music source.

This system will also be used for the comparison test of the tow ATs, with both ATs placed in the car and connected to the outputs of the A/B switch.
Apart from a thorough listening test, I intend to measure the output and plot the response of the ATs using TrueRTA.

Pictures and report will follow...