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Author Topic: Screws and ferrules for 200s?  (Read 2155 times)

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zambiland

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Screws and ferrules for 200s?
« on: June 04, 2013, 09:21:00 pm »

Anyone know where to get them? I've gotten a 200S from Craigslist that needs refurbishment and the back was put on with generic wood screws. Also, what are the official screws for mounting the speakers? There are some random bolts in there. Sadly, one of the D140s was replaced with a CTS square magnet speaker. I'm working on some JBLs and if worse comes to worst I have a D140-16 I can recone to 8 ohms, although I'm a little reluctant to take apart a perfectly good, original cone speaker.

Also, is the grill removable?

TIA for any information!

EdBass

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Re: Screws and ferrules for 200s?
« Reply #1 on: June 05, 2013, 08:44:51 am »

Any hardware store for the back cover fasteners, they are oval head machine screws with finishing washers. I don't have any in front of me but I think they are #10, 1.25".
I think the originals were chrome plated but I use stainless when I refurbish a Sunn cab, and I get them 1.5" long so they get a bite of "fresh meat" in those 40 year old screw holes.

The drivers are each mounted with four 1.25" long .25"-20 Black Oxide Pan Head Phillips Machine Screws that go into four .25"-20 T-nuts.

The 200S only came loaded with JBL D140F's, and four mounting bolts that were only tightened to "snug" was what JBL reccommended.
It might seem that using all of the eight available mounting holes and cranking them down would be the way to go, but four "snug" bolts is apparently the way to keep the frames from warping and distorting the close tolerance VC gaps in the old JBL's.

Most of my Sunn cabs that came to me needing JBLs now have 16 ohm K140's in parallel for an 8 ohm cab, but I have factory original cabs with D140F6's in parallel as well as several factory cabs with D140F's in parallel and one wired in series.
Personally, I wouldn't even consider reconing a strong factory D series JBL. You can't get the original cones anymore, and I think the 16 ohm drivers are more desireable for multiple driver cabs.
Get another D140F6 for your 200S, or maybe add a K140-16.

All of the factory 200S cabs I have indeed have removeable grills; just not easily removable...
They are screwed in from the back, a monumental PITA to remove.
This is a picture of a 2000S cab, but the grill frame mounting is the same on the 200S. The arrows point to a couple the grill frame mounting screws but they go all the way around the frame, including areas seriously restricted by the drivers and port ducting.



As I mentioned; a monumental PITA to remove.


Good luck with your project!




zambiland

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Re: Screws and ferrules for 200s?
« Reply #2 on: June 05, 2013, 09:23:04 am »

Thanks for the great info!

As far as the 4 bolt speaker mounting goes, that was also the original recommendation from JBL. I learned that lesson the hard way back in the 70s in high school!

I have found another D140-8 that a friend is donating to the cause. It would, in some ways, be nice to find another 16 ohm as with an 8 ohm cabinet, I can run another cabinet or still get full power on this one. (My Showman has a Mercury Magnetics OT with multiple taps).

EdBass

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Re: Screws and ferrules for 200s?
« Reply #3 on: June 05, 2013, 10:17:11 am »

Thanks for the great info!

As far as the 4 bolt speaker mounting goes, that was also the original recommendation from JBL. I learned that lesson the hard way back in the 70s in high school!

I certainly wasn't trying to take credit for inventing the JBL mounting procedure, I learned it the same way (and era) you did ;-) !
The 200S only came loaded with JBL D140F's, and four mounting bolts that were only tightened to "snug" was what JBL reccommended.

I have found another D140-8 that a friend is donating to the cause. It would, in some ways, be nice to find another 16 ohm as with an 8 ohm cabinet, I can run another cabinet or still get full power on this one. (My Showman has a Mercury Magnetics OT with multiple taps).

With any transformer coupled amp you can get "full power" regardless of the load impedance, provided the OT has a tap that will match the load with the output stage.

Even with transistor amps without a matching OT I think the whole "full power" thing is generally over rated, I would rather run my output devices at a stable, "thermally friendly" higher impedance and give up the maybe 2-3dB between 8 and 4 or 4 and 2 ohm output loads.
To get louder add speakers and/or amplifiers.
Of course the following is more relevent to SR than MI applications, but you also get the benefit of being able to "double up" if something goes south on you live. If your amp(s) are already at minimum load and one of them gives up its magic smoke, you are SOL.
If you are running your 4 ohm capable amps at 8, or your 2 ohm capable amps at 4 you can "double up" on one and still have a margin for error impedance wise.

Sorry to digress, but that "full power" thing is one of my (many) peeves...

zambiland

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Re: Screws and ferrules for 200s?
« Reply #4 on: June 05, 2013, 12:43:35 pm »

No need to apologize, those are excellent points!I guess what I was implying was that with both a 4 ohm and 8 ohm tap on my OT, an 8 ohm cab would be a good default as I can then add another 8 ohm cab right out of the head very easily. A 4 ohm cab is a bit more limited without some fancy wiring, but then, I can, as you point out, always run a reasonable mismatch. As you know, tube amp mismatches don't have the same consequences as OTL solid state amps, in terms of gaining power output with lower loads.

I've never used an OTL tube amp, so that's uncharted territory for me.

Here's hoping that our combined experience can prevent someone from warping speaker frames!

I inquired with Orange County about reconing options and they also told me about remagnetization, saying that in their experience an AlNiCo magnet loses about 1% a year. Have you gotten any remagnetization done?

Thanks,
Edwin

Soundmasterg

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Re: Screws and ferrules for 200s?
« Reply #5 on: June 06, 2013, 10:51:52 pm »

No need to apologize, those are excellent points!I guess what I was implying was that with both a 4 ohm and 8 ohm tap on my OT, an 8 ohm cab would be a good default as I can then add another 8 ohm cab right out of the head very easily. A 4 ohm cab is a bit more limited without some fancy wiring, but then, I can, as you point out, always run a reasonable mismatch. As you know, tube amp mismatches don't have the same consequences as OTL solid state amps, in terms of gaining power output with lower loads.

I've never used an OTL tube amp, so that's uncharted territory for me.

Here's hoping that our combined experience can prevent someone from warping speaker frames!

I inquired with Orange County about reconing options and they also told me about remagnetization, saying that in their experience an AlNiCo magnet loses about 1% a year. Have you gotten any remagnetization done?

Thanks,
Edwin

The guys at Weber recone JBL's too, and demag and remag during the process. They do a good job and their cones sound good when compared to original JBL's. JBL's were Ted Weber's favorite speakers so he spent the time to make his replacement cones sound pretty close to the originals. You can check them out at www.tedweber.com. I've had them do two different D140's and a D130 and they all sounded pretty nice.

Greg

zambiland

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Re: Screws and ferrules for 200s?
« Reply #6 on: June 07, 2013, 11:40:19 am »

Thanks for chiming in, Greg! I didn't know they did the remagnetization.

Ed, I went to hardware store and the size of the cabinet screws is definitely something else. I didn't have time to poke around and compare, though. #10 seems way thicker than the originals.

EdBass

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Re: Screws and ferrules for 200s?
« Reply #7 on: June 07, 2013, 11:59:36 am »

Maybe it's a #8; it's been a few years and many projects ago which is why I added the "I think" in my original post.
#10 sticks in my head though, I may have gone wider as well as deeper with the new screws. I looked around my shop a little but couldn't find my leftovers, they may be holding up pictures or something similar if my wife happened to go out to the shop looking around for such a device.

I'm sure about the driver mounts though, I found those extras. I had to order them from Fastenal though.
If you are in the same situation in your neck of the woods, the Fastenal part #'s are;

Screws 0148869
T-Nuts 1137964
 

zambiland

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Re: Screws and ferrules for 200s?
« Reply #8 on: June 07, 2013, 12:09:16 pm »

Thanks! I did pick up some of the speaker mounting bolts. They aren't the nice black ones, but they'll do for now and are better than the random whatnot that's in there. I'll order some from your link. At this point, I'm just going to play it as is until I get all the right drivers lined up.

Have you changed the damping material in your cabs at all? It seems pretty minimal in there.

EdBass

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Re: Screws and ferrules for 200s?
« Reply #9 on: June 07, 2013, 12:58:38 pm »

Sunn cabs came stuffed with a couple of different materials and schemes depending of the era. My older cabs have gobs of fiberglass batting on all opposing walls, my later one have a half inch or so of foam rubber on all internal surfaces.
Don't think it matters too much as long as you've got some form of damping, at least covering opposing walls.
However I prefer not dealing with the fiberglass batting, far "itchier" to deal with!

I flirted with going hi tech with damping materials and overboard with the amount when I refurbished my first old Sunn cabs, but before the fresh hardware, before the repaired/replace tolex and grill cloth, the first thing I always did was to get the proper drivers in, button them up and fire them up.
Frankly, to my ears they always sounded great the way they were. Although I'm pretty anal about my gear, I never saw (or rather heard) the need to mess with damping.

As the say; If it ain't broke...

zambiland

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Re: Screws and ferrules for 200s?
« Reply #10 on: July 09, 2013, 12:14:03 pm »

Thanks! I just got a second D140 today, and I think I'll get some polyfill batting from JoAnne Fabrics and get this thing all put together right for this weekend's gigs.