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Open Baffle Epiphany!

The PE tech guy says the back on the ASD tweets is not removable. No worries as I'm crazy for what the Zeniths do on their own.

Should I ever add more tweets I've got some piezo's laying around somewhere that might be worth a try.
 
hnash53 said:
Just got a pair of Heppner AlNiCo full rangers with the following numbers on them:

SP CO224
A024398-0
575425

They are 8", 8 ohms... and have them mounted on some temporary baffles to evaluate the sound... pretty good so far. Amazing that such "old" speakers sound so good.

Here they are: http://www.ebay.com/itm/292016751722?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT

Couple of questions: each cone has a small tear in it. What is the best way to repair it? The tears are small in the paper cone... maybe 1/8-3/16" in length. However, the tears cannot really be seen in the pics in the link above.

Is there anything to paint on the "accordian" surrounds to help preserve them?

Finally, I cannot find the detailed specs on these. Can someone/anyone provide info or a link?

Many thanks.

EDIT: The "575" indicates Heppner. The "425" indicates year "4" and week "25"... maybe 1964 week 25? But still no specs.
Click to expand...

Interesting full range speakers. You can try white glue on them ( Aleenes is what most use ) and it drys clear. The only preservative I've used on cones and surrounds is the "Wet Look" from Parts Express. Used it on some ugly faded woofers and they looked 100% better and it also tightened the bass.
 
Poultrygeist said:
Interesting full range speakers. You can try white glue on them ( Aleenes is what most use ) and it drys clear. The only preservative I've used on cones and surrounds is the "Wet Look" from Parts Express. Used it on some ugly faded woofers and they looked 100% better and it also tightened the bass.
Click to expand...

Thanks for the reply. Aleenes and the Wet Look have both been suggested for this elsewhere, too.

I listened to the Heppners for about 5-6 hours last night in my temp baffle... the sound is amazing and they have some bass, too.

These are the first AlNiCo speakers I've ever had... the smoothness is palpable.

EDIT: Just found this http://www.alnicospeakers.com/

They have and sell some AlNiCo speakers available and the prices seem fair. No affiliation other than as an interested customer. No more facebook presence, not much in the last 8 months or so. Maybe defunct?
 
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Thanks for the replies... much appreciated.

I got up close and personal with the small cuts in the the surrounds of these speakers. They are just small tears that didn't even open up upon examination.

So... my goal changed to simply prevent anymore tearing. I had some Duco Cement and used a small plastic applicator to get the cement into the small tears... seems to have worked.

I decided not to treat the cones/surrounds with anything out of fear that any treatment that added something not there would change the character of the sound from these.

I find it amazing that these speakers... I think made in 1964... sound so good. I guess the AlNiCo magnets don't hurt either.
 
hnash53 said:
I decided not to treat the cones/surrounds with anything out of fear that any treatment that added something not there would change the character of the sound from these.

.
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Exactly!
With FR's, you want the cone as light as possible. I think the sun bleach job on my Zeniths may have lightened them by a few milligrams.
Now if rolling off highs and tightening bass is something you desire, feel free to add stuff.
I really wanted to dye the cones and add some treatment to the "skiver rolls", but I know I'll wreck them. I'll just paint the gaskets like PG did.

Hey Poultrygeist, how do you feel about dampening those "ring like a bell" Zenith frames? Or would it damp them to death?
 
Son-of-Vere said:
Exactly!
With FR's, you want the cone as light as possible. I think the sun bleach job on my Zeniths may have lightened them by a few milligrams.
Now if rolling off highs and tightening bass is something you desire, feel free to add stuff.
I really wanted to dye the cones and add some treatment to the "skiver rolls", but I know I'll wreck them. I'll just paint the gaskets like PG did.

Hey Poultrygeist, how do you feel about dampening those "ring like a bell" Zenith frames? Or would it damp them to death?
Click to expand...

Haven't noticed any ringing but it won't hurt .
 
IMAG006.JPG
 
Just read on another forum that Hawthorne Audio which specialized in OB speakers is no more.

The owner decided to go full time into his sideline business of historic home restoration.
 
Open Baffle Design: what is the story regarding rear mounting vs. front mounting? I've read some say that rear mounting has a negative effect on the dispersion of the sound from the drivers. Then I've read elsewhere that even front mounting creates issues, too, with dispersion.

But maybe... just maybe... the open baffle design largely negates these issues? I'd like to know because I'm going to be fabricating some baffles for some vintage full rangers.

Thanks!!
 
Wasn't there something about the air mass in the opening that a rear mounted driver had to overcome? That it acted like a port?
Truly the best way to mount a driver is flush with the baffle, but that requires a router, and I'm having a hard time justifying the cost.
 
Front recessed mounting looks very nice but you lose some of the baffle material and perhaps some strength. Front mounting is just so much easier and It's all I'll probably ever do.

You often see very thick layered baffles with lots of dampening and elaborate bracing, magnet mounting etc. but unless you play at high volumes ( enough to excite the baffles ) can't say it makes that much difference. Most of my baffles these days are 3/4" MDF and instead of painting them ( which is difficult ) I cover them with thick wall paper. If you look at the Zenith baffle you can see that I painted the textured wall paper for a tooled leather effect. With the wall paper covered MDF the knuckle rap test gives a fairly dead sound.

Cutting MDF is not fun due to the devil dust but I've found my local Home Depot willing to cut it for no charge if it's bought there. After HD makes the straight cuts I take the baffles home and rout the speaker holes outside while wearing a mask. You can cut the holes with a jig saw if you take your time. They just won't look as nice from behind.
 
Mojo Warrior said:
Some recommendations for 10 inch woofers?
Click to expand...

Might be interesting to slap a couple of the 10" GRS 4 ohm subs ($19.80 each at P-E) in one of these and see how it sounds? Qts looks appropriate and they have decent X-max, so it might be a pretty low cost way to get some OB Bass? The Peerless 830668 SLS sub driver looks interesting also (pricier, but probably better?).
 
Poultrygeist said:
Parting out an old console is how I came upon the Zeniths. I think I paid $35 for the console and sold it's tube amp and other parts for around $150. Glad I hung on to

the speakers which turned out to be keepers. Most of the guys who hunt down and harvest tube amps from consoles care little about the speakers. Oftentimes you can

find them for not much money on eBay.
Click to expand...

Just bought one off the bay. Now I need another.
 
Phase 2 of the OBE. Can you see the dilemma I'm having? The sound appears to emanate from the entire baffle, and this is a good design, but they're freakin' HUGE! I really want to commit this design to wood, but their appetite for space can be a real problem. In this mock-up form, they are very light, I mean one handed carry light, and I could live with them at this weight. However, there's a reason why cabs and baffles aren't made from single sheets of corrugated cardboard, and the boink noise is tough to deal with.These do however have a surprising amount of bass.
I'm wondering if I could get away with a 3/8's inch baffle and brace it. These with never see over 4 watts anyhow.

 
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