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Recap Resistor question

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F1nut:
I looked around a bit, but didn't find the info on your speakers that I was looking for. Are they ported, sealed or what?

What are the -3dB specs?

Slim-Shaddy:

--- Quote from: F1nut on September 07, 2012, 01:17:46 PM ---I looked around a bit, but didn't find the info on your speakers that I was looking for. Are they ported, sealed or what?

What are the -3dB specs?

--- End quote ---

They are sealed with a 12" woofer, 8" lower mid, 1.5" upper mid, and 1" tweeter. I don't know what the FR is, but they are the first speakers designed by Roger Russell that didn't need an EQ for bass.

From the Roger Russell site:
4-way floor system has 12" woofer, 8" lower mid, 1-1/2" dome upper mid and 1" soft dome tweeter. Walnut finish. Black grille cloth.

Red and yellow level indicator lights at bottom right. Red light indicates tweeter fuse blown. Yellow light indicates maximum power level. Main and tweeter fuses are located at the back of the cabinet.

This was the first of the smaller systems to be designed in our new anechoic chamber.

Crossover frequencies: 250Hz, 1.4kHz and 7kHz
Impedance: 8 ohms
Output: 89dB @1w/1m
Power rating: 150w
Size: 35-5/8"H, 17-1/2"W and 11-3/4"D
Weight: 75 lb
Sold from: 1980 to 1985

F1nut:
Yeah, that's the same info I found. Interesting that they don't list the frequency response.

Since they are sealed there is a tweak you might be able to do depending on the location of the driver screw holes on the baffle. If you can do this it will help clean up the mid-range and improve the bass response. This assumes the drivers are simply screwed into the baffle with wood screws right now.

Install Hurricane nuts (not T-nuts) with an 8-32 thread pattern by drilling out the holes to accommodate the Hurricane nut shaft size. You want to use a drill size slightly under the nut shaft diameter. Then use 8-32 cap screws to mount the drivers to the baffle. This couples the drivers much tighter to the baffle than can be done with wood screws. It really works. Also, be sure to check the driver gaskets for any damage.

While you have the drivers out, if the baskets are stamped steel, go ahead and add Dynamat Exteme to the spokes. This helps eliminate ringing, which will also help clean up the mid-range.

F1nut:
Another worthy tweak to increase bass response is to add spikes to your speakers.

MacGeek:
Mac never stated frequency response characteristics until after Roger retired and Mac moved to 4 ohm ratings.  I'll speculate the speakers (XR 16's if I recall correctly) have some useable output at 20hz, depending on the room and placement.  I have measured this model before, in more than one room.  They tend to rise just a bit over 10k hz, plateau and then start to roll off at the last 1/3 octave, maybe a bit lower, again depending on the room and placement.  They sound very good with a little bit of a hump (just a db or two) at 50hz.

You don't need an EQ to benefit from measuring the room-it's very helpful to determine placement, height off the floor, toe-in, etc.  If you can, try raising them until the tweeter is just above ear level (it may look bad, spousal harmony comes into play here).  This reduces low frequency floor bounce and let's the high end open up a bit.

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