N-3000-F

[ZilchLab]

Any insights?

Do I have the driver impedances correct for Seville?

Scroll up for the pics:

http://audiokarma.org/forums/showthr...98#post1686198

[bfish]

Hey dude,

The '75 ref lists the 847A as another one of those 8/16 systems you're so fond of...

The woof's a 16, but the 3000G impedance isn't noted. From catalog listings, the 3000A was 8 ohms, and so was the 3000H, (same guts, different horn). If I had to guess, I'd bet the G was too. Considering how easily you can fry a 3000 horn, and since there's only one place in the world you might get them fixed (MicroMic) it would pay to know for sure.

Those guys knockin' 3000s never heard a good one.

Do you have access to Baranek's "Acoustical Measurements"?

[bfish]

How 'bout building in some HF protection on this one?

[hmole]

I talked Micro Mike and Bill about those and they both recommended putting in a fuse, they are not cheap to fix, and a little fuse is cheap...
Unfortunately Mike was going to recommend a value for but never did, anyone have an idea? 5 watts is the recommended power on those I think.
I have a burnt one if someone is interested. No more than shipping cost on that.
Harry

[hmole]

I measured two and they seem to come out to around 11.3 ohms, I would bet they are nominal 16 ohms.
These were on 601c, I have a 601D around I could measure that as well, but I bet it is similar.
I think the t3000 was the longest running production driver they had, that must mean something. Started late 30's or early forties and ran up to the 80's sometime I think.
Harry

[bfish]

Originally posted by ZilchLab:
Don't know Baranek, alas. What am I lookin' for there, and where?

<font size="2" face="Verdana, Helvetica, sans-serif">From Altec Graybar Dealer Letter # 79 (7/15/55);

"The 3000A High Frequency Unit uses the identical pressure unit which was charted up to 100,000 cycles in Professor Beranek's Engineering textbook "Acoustic Measurements" referred to in AGD #71."

Was just curious about 'the rest of the story'. So many of my questions lead to a reference to that book though, I guess I ought to buy a copy.

An autopsy on my open circuit pair of 3000 drive units showed that the coils hadn't really burnt, but had simply lost contact with the leads wires. Doesn't really matter though, as the assembly process ( see the Bell assembly patent) doesn't allow repair without the special assembly device, which apparently only Bill Hayes has. Based on that failure mode, it also stands to reason that DCR readings (and performance) might be affected accordingly on functional units.

Harry, did Bill Hayes quote a repair price?

[ZilchLab]

Originally posted by bfish:

The '75 ref lists the 847A as another one of those 8/16 systems you're so fond of...

Do you have access to Baranek's "Acoustical Measurements"?

How 'bout building in some HF protection on this one?

<font size="2" face="Verdana, Helvetica, sans-serif">I'm thinking I should put a "?" in there for the tweeter impedance.

Don't know Baranek, alas. What am I lookin' for there, and where?

Not above using protection, of course. Also not yet sure what's going to happen with these. It's clear they want a rebuild, 'cause I'm fresh outta beeswax....

<font color="#FFFFFF" size="1">[ March 01, 2008 12:54 AM: Message edited by: ZilchLab ]</font>

[hmole]

Can't recall exactly, but it was in the $100+ range, he was trying to collect a batch to do, I think he wanted a batch of 10 or so to make it worthwhile.
Harry

[hmole]

Can't recall exactly, but it was in the $100+ range, he was trying to collect a batch to do, I think he wanted a batch of 10 or so to make it worthwhile.
Harry

[donaldpatten]

Hi
I have Leo Beranek's Acoustics text book. Circa 1954, from MIT , & B.B.and N.
I looked for ref to 100,000 cps and horns ,etc... and found nothing.
I surmise some wishful thinking ,or one too many zeros got in the way.
Don