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Ohm F questions?

Thanks guys. Hopefully after the holidays I'll make some moves towards getting my "f"s on the road to recovery. I'll have to figure out how stiff to go on the spiders as everyone seems to agree that the originals are too soft and sag.
 
W9TR said:
I bought my first pair of F’s in 1975. After blowing them up several times I opted for the Walsh 4 trade in program. I thought the 4’s sounded better in some ways but they clearly lost that F magic.

Fast forward to 2012 and I found a physically excellent pair of F’s that needed to be refurbished.

I sent the drivers to MillerSound and had Bill refurbish them. He removed the hardened clay backing from the titanium section and added several strips of dynamat. He replaced the foam backing on the aluminum section. He replaced the voice coils, surrounds, and spiders.

These new drivers have been performing spectacularly well for several years. I think they sound better than the originals but 35 years is a long time for audible memory. :)
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One other question, if you don't mind. When Bill replaced the voice coil did he use an 8 ohm or 4 ohm coil? I think I read that guys were finding the 8 ohm coil to be easier on amplifiers but I think the original was 4 ohms made with flat aluminum wire. Of course I'm not sure what options are available anymore, v.c. -wise.

Lab
 
4 ohm VC. It was a more conventional kynar insulated copper coil as opposed to the OEM flat wound aluminum VC. Also he indicated that the ferrofluid Ohm used would escape the gap and attack the adhesive used to glue the voice coil former to the cone. That was certainly true for my drivers as it was easy to pull the VC’s off the cones.
 
W9TR said:
Lab,
He placed four 1/2” wide strips of dynamat on the inside of the titanium tweeter section from the voice coil to the where the titanium and aluminum sections are joined together. He said it does a better job of dampening ringing than the old clay did.
Tom
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I feel like Peter Falk coming back and asking "just one more thing, sir...", but, when I was looking over the dynamat listed on those sites whose names we dare not speak, it seems to be available in numerous different thicknesses. 1/8, 1/4, 3/8, 1/2, and even 3/4" thick. Could you hazard a guess about what thickness Bill used? I could easily see over or under damping the titanium if I guess incorrectly.

Also, the foam which was on the aluminum middle section- it looks like open celled foam but there's not enough left to be certain. I'm guessing 1/4 or 3/8" . Some sort of 3m spray adhesive to hold it to the aluminum I guess?
 
Lab,
Those are really good questions. I’m afraid I don’t know the answer to either of them. Perhaps others can chime in.
Tom
 
Harvestor said:
Is it true that the A has much Lower Bass than the F that can be Felt in your chest?
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It gets noticeably lower than the Fs. I never felt it in my chest, maybe that is just my chest at work here as I don’t feel things there. However the Ohm As are capable of propagating clean ripples on the surface of my leather sofa. No ever speaker has ever done that.
 
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Harvestor said:
Are the cabinets much larger than the F ?
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Yes, they are wider and taller. I can move the Fs by myself even when they are assembled. The As - absolutely no way! I can’t even move one of the bases by myself, let alone an assembled A with the driver on top.

Though they are truncated pyramids the As are a bit more squat in overall profile than the Fs.
 
Harvestor said:
How many A models we're produced?
Is it easier to Referb the A vs the F?
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I don’t know how many pairs were made, but I know it is less than 40. I don’t know if even Ohm knows for sure. I have heard the quantity of 37 pairs mentioned more than once.

The A has a treated fabric surround, so there is no need to re-foam. I don’t believe the As ever need refurbishing, and it is my understanding that all of the As that were made are out there stilll working. John at Ohm told me that if you find a pair of As in the wild, they probably still work. If you find a pair of Fs, they probably don’t!
 
Don_SA said:
No I am about 1,000 miles from there at present.
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Damn..
It would be such a fun thing for me to at least hear a set of A for an afternoon.

Personal question why haven't you been on the forum much over the years?

Seems like person like yourself could have some knowledge to share at least once a month... Anyway I'm grateful for your responses and happy that you returned turn the Forum..

I have wanted to get a set of ohm speakers ever since 1978 when my brother brought home a pair of H and miraculously since April I've acquired the model I the model C2 and the model H all as if by a miracle

IMG_20181207_215322033.jpg

I am very grateful for what I have but it would be nice before I die to at least acquire a set of Model F.. that have been refurbished.. to complete my collection and if there was supernatural miracle a set of model A
 
Also I would like to know how many years you have owned the model A and how or what is the story of your acquiring the set of model A?
 
After reading ohms website on legacy product about the model A said that they were prototypes so it makes your story interesting or even the story of the person who got them before you I wonder did ohm just sell them to very particular customers?
 
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