Yamaha JA-0801

[headshake]

I am super curious about having one driver play 400-4000hz. This aligns with where our ears are sensitive to decay and flip to just caring about sound pressure. My hope is that this sucker lives up to the specs and decays to -25db in about 1ms. The mid will be crossed to the bliemsa t25b and seas l26roy.

The driver I got is still on the way so this all could be a bust. I think it might be 40+ years old? It is almost an ancient artifact!

My plan is mainly to A/B and see what REW says.

 

[gene_stl]

I look forward to you posting your results. I run my JA 801s from 1,000 to 5,000 Hz. They cross to tweeters from the NS 500 which was a two way crossing at 1800 hz. I think decay should be measured with a high damping factor amp directly connected to the driver(s). Surely a high level crossover network eliminates or reduces electrical damping and might have some gyrations of their own to contribute.

 

[headshake]

I look forward to you posting your results. I run my JA 801s from 1,000 to 5,000 Hz. They cross to tweeters from the NS 500 which was a two way crossing iirc at 2500 hz. I think decay should be measured with a high damping factor amp directly connected to the driver(s). Surely a high level crossover network eliminates or reduces electrical damping and might have some gyrations of their own to contribute.

Cheers! I forgot the amp is the hypex FA123. So DSP and classD are in the mix. I will also have some speak-ons between things. So not analog and clean as can be. But it should be fine?

Hey, we are both in STL! Come by and listen! I'll send a pm.

 

[headshake]

total bummer...

The ja-0801 won't play loud at all. My fusion plate amp goes into a clip mode if I crank it up. When I did REW sweeps you can see how it will only play some freq. as the volume goes up. I assume the coil is busted? Or something else?

I was able to stick a mic 6" in front of it. The baffle is 24"X24",


here you can see as I raise the rew volume it plays less and less.



1ms to STFU! I just wish I could play it louder.

The guy who I purchased it off of said his kid busted the tweeter and did not know the mid was broke. Ugh.

It stinks that this is all I can see.

 

[headshake]

So I made a "test" to try out on some speakers. Inspired by the multi-tone test and the limits of human hearing I made a special track. The track plays a cymbal and rings where ears are sensitive. It does this once with no alterations and a second time where 75% of the sound has 0.5ms spaces in between. The idea is to ask the speaker to shift between making noise and silence. 0.5ms should be the limit of what we can hear in shifts in sound around 2khz. I played each track and captured the sound with the RTA in REW.

This is what the breaks and what should be playing looks like:


JBL 580 vs Bliesma/ETON vs Yamaha (the Yamaha cuts out by 3khz so judge between 500hz and 3khz)

The levels were not matched. Even so, there is quite a bit of difference. Dotten = broken ringing sound, Solid = clean sound

Clean signal

Broken ring


yamaha ja-0801 only


Bliesma t25b + ETON 3-212 only


JBL 580


Kinda neat to see how they each express the file. On my coax (not shown) the broken ring sound sounds more like a thump of a drum + cymbals than just a ringing. My other takeaway is that the JA-0801 has very little loss of power when asked to play the broken ringing clip.


If I round things out and align the measurements around 1khz things don't look so dramatic.

 

[gene_stl]

Are you band limiting the pink noise going into the JA 801?

 

[headshake]

Are you band limiting the pink noise going into the JA 801?

My sweeps started at 200hz. No pink noise though. Just the REW sweeps and the RTA w/ the recordings. No filters were on the mid until the last graphs I posted. I thought it would be most fair if I made the mid flat between 500 and 3khz.

Here is what the JA-0801 looked like measured 7" or so away with the EQ:



edit: snap of the test baffle:


Such a beast of a driver! I had to cut a > 6" hole to put it in the foam baffle. I don't trust it too far off the floor since it is so heavy.

 

[headshake]

Ok.. I have some new data! The textreme woofer measurement comes from hifijim on diyaudio. The data is not adjusted for a mic calibration but still, there is something to see.

I made a sound test file that plays a cymbal mixed with 0.5ms silence every other 0,5ms. The textremes played the clip better than the Be dome! No "thud" sound with the test. You can see at 1ms and at between 500hz-700hz the yamaha dome does not decay flat. I think this is the thud sound I hear- it is something baked into the decay at 1ms. Well, that is my newbie guess anyways. With all that said, both drivers are fantastic and play the sound test better than most of my speakers.

SB A 6" Textreme VS Yammy JA0801



Now what happens after the first 2ms is another story. A dome will STFU faster. BUT I think I am learning that a flat decay at 1ms is more important than what happens later. The textremes kinda proved that to my ears.