whizzer and intelligibility ?

[hurdy_gurdyman]

One more time. Here is the LS12 with a ceramic magnet. not much difference. Betsy is looking better all the time...

Dave

 

[GM]

Hmm, from very dim memory these were fairly flat out to at least 7-8 kHz before mass roll off occurred and if the magnet was tired the bass would be shifted up to fill in the dip, which is what the stock box tuning did.

GM

edit: Huh! wonder what's up, never seen such a 'fast' roll off of a wide BW driver. How stiff are the spiders?

 

[hurdy_gurdyman]

Hmm, from very dim memory these were fairly flat out to at least 7-8 kHz before mass roll off occurred and if the magnet was tired the bass would be shifted up to fill in the dip, which is what the stock box tuning did.

GM

They measured a lot flatter with white noise, but I didn't realise I used it until I was all done. When I went back and measured with pink noise, they looked much worse. Last year I used the same program, using pink noise, to measure some modified Hawthorne Audio Sterling Silver 10" speakers that I added a 10 x 16 horn to the Radian 475. The measurements turned out excellent. I'll post one as an example... Am I doing something wrong this time? It's the same baffle (removable panels for different drivers) in the same location.

Dave

 

[hurdy_gurdyman]

Hmm, from very dim memory these were fairly flat out to at least 7-8 kHz before mass roll off occurred and if the magnet was tired the bass would be shifted up to fill in the dip, which is what the stock box tuning did.

GM

edit: Huh! wonder what's up, never seen such a 'fast' roll off of a wide BW driver. How stiff are the spiders?

All the test tones I've been running should have the spiders well re-broken in. I'm not sure whats going on. They don't sound nearly as bad as they look. I'm rather enjoying listening to late night Jazz on them right now.

Dave

 

[hurdy_gurdyman]

Here is the same EV LS12 1 meter measurement using a different program. Some is wrong with the REW program. Probably something not set up right.

Dave[URL=http://s16.photobucket.com/user/hurdy_gurdyman/media/EV%20LS12%20w-Utah%20horn%20no%20Augie%202-27-2017-D.png.html][IMGDEAD]https://i16.photobucket.com/albums/b29/hurdy_gurdyman/EV%20LS12%20w-Utah%20horn%20no%20Augie%202-27-2017-D.png[/IMGDEAD][/URL]

[IMG][URL=http://s16.photobucket.com/user/hurdy_gurdyman/media/EV%20LS12%20w-Utah%20horn%20no%20Augie%202-27-2017-E.png.html][IMGDEAD]https://i16.photobucket.com/albums/b29/hurdy_gurdyman/EV%20LS12%20w-Utah%20horn%20no%20Augie%202-27-2017-E.png[/IMGDEAD][/URL]

 

[GM]

Pink noise is the correct one. The first new measurement looks more 'right' on a fairly small OB, the second one not so much, especially in the 2-8 kHz BW, so which is the pink noise one?

GM

 

[hurdy_gurdyman]

Pink noise is the correct one. The first new measurement looks more 'right' on a fairly small OB, the second one not so much, especially in the 2-8 kHz BW, so which is the pink noise one?

GM

The last two (blue graph line) are both the same 1-meter measurement. The first is 1/48 smoothing, the second is 1/6 smoothing.

The colorful graph prior to that is from a different speaker a couple of years ago (same baffle). It is used to demonstrate that back then REW worked fine. Now I can't seem to get it to work right. The last two graphs (blue lines) is from synRTA.

Dave

edited to correct spelling*

 

[brig001]

Has anyone else tried criss crossing cotton thread across a whizzer to stop the bell mode resonance?

I stretched cotton thread aver a soup bowl in a very open weave to give hexagon shape 1cm holes (it was a big whizzer), painted it with PVA and let it dry. I then put a bead of PVA round the top edge of the whizzer and stuck it on. Stopped the bell mode completely on mine. Reversible too at a push. I have a photo somewhere and will try to find it.

Brian

 

[hurdy_gurdyman]

Has anyone else tried criss crossing cotton thread across a whizzer to stop the bell mode resonance?

I stretched cotton thread aver a soup bowl in a very open weave to give hexagon shape 1cm holes (it was a big whizzer), painted it with PVA and let it dry. I then put a bead of PVA round the top edge of the whizzer and stuck it on. Stopped the bell mode completely on mine. Reversible too at a push. I have a photo somewhere and will try to find it.

Brian

I haven't heard of this tweak (been off the forums for too many years). I would love to see pics when you finish them.

What speaker do you have with a large whizzer?

Dave

 

[brig001]

Found a photo. These we old McKenzie PA speakers that I made coaxial using some Monacor tweeters. I thought I'd made hexagons, but it was 5 years ago... I guess any shape will do, the point is to connect any given point on the edge to as many others as possible without adding too much weight. You can't see it in the photo, but the PVA is connecting the threads where they cross.

Brian

 

[hurdy_gurdyman]

Found a photo. These we old McKenzie PA speakers that I made coaxial using some Monacor tweeters. I thought I'd made hexagons, but it was 5 years ago... I guess any shape will do, the point is to connect any given point on the edge to as many others as possible without adding too much weight. You can't see it in the photo, but the PVA is connecting the threads where they cross.

Brian

Very cool! I may try something like that on my EV's. I can't pinpoint any abnormalities in what I hear, but occasionally female vocalists have a bit of a buzzy noise on certain notes. Not sure if it's from the main cone or whizzer. Trying to pin it down. Otherwise, they pretty decent from about 60 Hz - 9 kHz on an open baffle.

Dave

 

[GM]

Has anyone else tried criss crossing cotton thread across a whizzer to stop the bell mode resonance?

Haven't seen/tried it, though some folks have used fine mesh screen to 'cap' it; my preference is to knead the starch out of it and if too limp, then use cheap lacquer hairspray or shellac or Dammar to fine tune it as required.

GM

 

[GM]

....but occasionally female vocalists have a bit of a buzzy noise on certain notes.

Normally a whizzer, though the $0.98 tweak sometimes cures it, but guessing it won't on a big one unless a relatively dense damping material is used.

GM

 

[hurdy_gurdyman]

Haven't seen/tried it, though some folks have used fine mesh screen to 'cap' it; my preference is to knead the starch out of it and if too limp, then use cheap lacquer hairspray or shellac or Dammar to fine tune it as required.

GM

Haven't heard of that one, either. Maybe it would be worth buying one of those inexpensive 8 inch coaxial drivers (the Pioneer replacement) and practicing the technique until it's right before messing up a more expensive (or nice vintage) driver. I'd hate to mess up one of my EV's with a non-reversible tweak.

Dave

 

[hurdy_gurdyman]

Normally a whizzer, though the $0.98 tweak sometimes cures it, but guessing it won't on a big one unless a relatively dense damping material is used.

GM

I have one bad EV driver that is patched up like a rag doll that I might see what I can do with the whizzer. Seeing as the driver is close to as old as I am, I'd guess the paper is so dried out that almost anything might improve it.

Dave

 

[hurdy_gurdyman]

I have always found whizzers fascinating. Kind of like women, you can't live with them, but you can't live without them.

When whizzers are well designed, thay can truly make a fullrange/wide range driver sound great with that coherent realism. But many of us can't afford to buy those elaborate drivers, so we search for ways to tame the affordable ones.
Once you've heard a good fullrange driver, it's hard to go back to multi-way crossover burdened speaker systems.

Dave

Getting sleepy, time for bed. Goodnight all.

 

[GM]

Definitely if you're wanting to ultimately sell or bequeath it, then leave it stock and rely on strictly reversible mods. I did all my testing on old radio, TV, music console, automotive drivers, though if I could of foreseen the internet, etc., way back then, there was a bunch of field coils, AlNiCos I would have lovingly stored, but at the time they were just small, 'old', so here in the 'land of plenty', considered no great loss at the time.

GM

 

[GM]

Seeing as the driver is close to as old as I am, I'd guess the paper is so dried out that almost anything might improve it.

No longer have any older than me, only ~9 yrs younger, a Jensen LS15 and some Altec 515Bs, so still pretty ancient. Hmm, IME the pulp binder, any doping used don't dry out on pulp paper diaphragms; only that undoped, thinner hinge points will eventually tear if abused with high excursions and/or in an environment that attacks the chemicals. The paper fibers in Jensen's hinge is starting to fray enough to look like little cotton tufts in places, so need to coat the entire surround with something pretty soon.

Anyway, good luck with it, curious to find out if the $0.98 tweak will do much for bigger whizzers; can't recall if anyone did any of the big Eminence whizzer drivers.

GM

 

[hurdy_gurdyman]

Going to be sampling Betsy this week, so maybe the EV's can be retired. I've read lots of good things about the Betsy drivers. I also found a good conditioned EV LS12 to replace my really beat up one. It'll be here next week. Looks like I'm going to have some OB fun!

Dave

 

[hurdy_gurdyman]

My Betsy drivers came in. Played them for a few hours than did a couple tests, mostly to match up the Hawthorne Audio 15 inch "Augies" to them. I thought I'd post this graph from my listening seat about 12 feet from the speakers. Following that, I'll post the graph I made of the EV LS12's at my listening seat. Both were made a few days apart for the purpose of integrating the bass drivers.

Here's the Betsy:

An externally hosted image should be here but it was not working when we last tested it.