Recap Resistor question

[MacGeek]

Ed,

Pianos n Stuff in Blawnox rents (or used to rent) equipment to measure your room.  A Rane RA 30 provides full bandwith Pink noise and a 1/3 octave RTA.  It will show where your room has humps, or dips in frequency response.  Even with out an EQ, you will be able to instantly see changes due to variations in speaker or furniture placement or through use of tone controls.  You might also be able to measure changes in the speakers performance before and after xover mods.  The rental cost was reasonable the last time I used one.

My personal experience suggests proper EQ will make more difference than xover component changes (except for repair of defective parts).  It can make good speakers sound great and great speakers blow you away.

[SunnyDaze]

Sorry Jesse. I should read more carefully.

[Slim-Shaddy]

Thanks for all of the input. As far as contacting R Russel.. I've asked him before about replacing the caps and he seemed to really dislike the idea, sating that there is no reason for it becaufse they should all be fine. He is great to talk to for advice about repair, but when it comes to updating or altering the speakers in any way, he seems to almost get offended.

Jesse,
Changing the inductor that goes to the woofer seems like a good idea.

klaus,
I would love to pick up a MQ, just to throw it on the system to see what kind of difference it makes, but they are not cheap. To be honest, I think it's asinine how much they are going for. For about the same price KRK makes a digital room corrector with a mic, which should remove the guesswork, and seemingly be an easier solution.

[SunnyDaze]

My SS-315X has a spectrum analyzer. If you can find the mic cheap on ePay, we can use that to measure SPL at various frequencies about your listening area.

[F1nut]

I should have also mentioned that upgrading the electrolytic caps to film/foil types WILL result in an increased bass response. You might want to try that first before changing inductors to see if that cures the bass shy issue.

I know some folks say that the shunt caps don't matter, etc., etc., but I beg to differ. Normally, I'd recommend Sonicap Gen I's, but the values needed are too high, so you'll have to go with Solen or maybe Dayton for the shunt caps.

[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]

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?

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.

[SunnyDaze]

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.

Wow. That's great advice. I never would have thought of that. Simple, but very effective.

[OldiesButGoodies]

Be back in an hour - need to hit Ace for hurricane bolts and see if Bebst Buy still carries Dynamat.

[F1nut]

I doubt Ace carries the Hurricane nuts and cap screws, so if they don't have them you can order them from Parts Express.

A tip for mounting the Hurricane nuts. After drilling out the holes place the nut in position on the backside of the baffle. Use one of the cap screws with a thick washer and drive the cap screw into the Hurricane nut. This will pull the nut into the hole, which is better, easier and safer than trying to hammer the nut in from the backside. Don't go crazy with the torque, you just want to seat it.

[TNRabbit]

Is this what they look like?

[imghttp://home.comcast.net/~mc_audio/XR16.jpg[/img]

[TNRabbit]

Sorry, bad url; here: