Need help on a project: Taming the bass in Fraziers

[drspiff]

I have a pair of Frazier speakers, (the size up from the Monte Carlo I think) 24" tall, 14" wide, 10" deep, well constructed, veneer over 3/4" multi-layer ply. There is no model number. These are ported speakers with 2 tweeters and a single 10" woofer. The only crossover mechanism is a single 3uF cap. Yesterday I recapped them and they sound fine at low volumes. However, at higher volumes they are very "boomy". They remind me of JBL speakers as I remember them from my youth. (no offense intended)

I consider these to be project speakers since the market for Fraziers is "soft". Meaning that most people have never heard of them.

I would like to try to tame the bass on these speakers. My thought is that a crossover of some type or cab alterations could go aways toward making them more civilized. If any of you budding speaker engineers are willing to help, let me know. I'll take whatever detailed pictures, measurements, or whatever you require.

 

[RS Steve]

I have a pair of Frazier speakers, (the size up from the Monte Carlo I think) 24" tall, 14" wide, 10" deep, well constructed, veneer over 3/4" multi-layer ply. There is no model number. These are ported speakers with 2 tweeters and a single 10" woofer. The only crossover mechanism is a single 3uF cap. Yesterday I recapped them and they sound fine at low volumes. However, at higher volumes they are very "boomy". They remind me of JBL speakers as I remember them from my youth. (no offense intended)

I consider these to be project speakers since the market for Fraziers is "soft". Meaning that most people have never heard of them.

I would like to try to tame the bass on these speakers. My thought is that a crossover of some type or cab alterations could go aways toward making them more civilized. If any of you budding speaker engineers are willing to help, let me know. I'll take whatever detailed pictures, measurements, or whatever you require.

I'd be curious to what amp or receiver you are using them with, I own a bunch of different Frazier models and none I would ever call "boomy". Most Frazier's have a simple crossover in which the woofer is either run wide open or has a coil in line. I find most Fraziers to have a punchy bass, maybe you could post some pictures of yours (inside and out) so we can get the model figured out for sure.

 

[cablephil212]

Try to make the port tube longer if possible. You could try some cardboard rolled to fit over the existing port inside the box. Add about 6" to the port, as a starting point.

Once you've tuned the box to your liking, you could replace the old port with the new sized tube.

You could also try putting some poly fill right behind the woofer.

Experiment. That's what this hobby is all about.

Have Fun

 

[drspiff]

I'm currently running the Fraziers through a KR-7600 that I just brought back online. And I can certainly use another receiver to drive them.

Here are some pictures of the box and insides. And I was wrong about the crossover. I only replaced the 3uF cap. The XOVR also has a 2.25mH inductor and a 30ohm pot.

Regarding making the port deeper, there is only about 1" between the insulation and the mouth of the rectangular port.

 

[alteclipsch]

I have 10" Frazier woofers in Electrovoice cabinets with about the same dimensions and just an open tweeter hole on the baffle. Not boomy at all, but I have the round magnet blue version, I imagine they're different than yours. I haven't taken the time to build in a slot-port or add a tweeter, but the 10 seems remarkably capable by itself. These are sleeper speaker, IMO.

 

[drspiff]

These are sleeper speaker, IMO.

Yeah, I'm inclined to agree. I actually have 3 pair of Fraziers. This set, another in the same size cabinets but with what looks like a horn instead of 2 tweeters. That set is labeled MkIV and has front mounted "brightness" control. The 3rd pair is short and squat, and has the same woofer as the other 2 pair, but includes both a horn and tweeter. At least what looks like a horn and tweeter. This is the Concerto model. I really want to get all of them capped and back on their feet.

 

[cablephil212]

I'm currently running the Fraziers through a KR-7600 that I just brought back online. And I can certainly use another receiver to drive them.

Here are some pictures of the box and insides. And I was wrong about the crossover. I only replaced the 3uF cap. The XOVR also has a 2.25mH inductor and a 30ohm pot.

Regarding making the port deeper, there is only about 1" between the insulation and the mouth of the rectangular port.

WOW

That's an awful lot of fiberglass for a "ported" box. Plus, it's kinda dangerous having the fibers blowing into the living space. NOT healthy at all. Usually, the damping goes on 3 surfaces: Top or Bottom, 1 side, and the back. I also didn't realize it was a slot port.

OK, here's what I'd do as an experiment. Leave the big piece (behind the woofer) out. If you have any poly fill, take some and stuff the port. You're gonna have to do this a couple of times to get it right, so DON'T use every screw to attach the back in place. 2 should be enough for this. The poly will give a little resistance to the port output. That just might cut down on the boomyness (spelling?). Just keep adding until it sounds good to you, then duplicate it for the other box. Also, try putting back the damping behind the woofer after the poly is adjusted to your liking. See (hear) if it makes a difference.

The cap is for the dual tweeters, and I'll assume the coil is for the woofer. Is that right?

 

[drspiff]

Thanks for the pointers. I'll play with the fiberfill and the current insulation.

 

[cablephil212]

Thanks for the pointers. I'll play with the fiberfill and the current insulation. Just because I could, I've included a schematic of this "no-name Frazier".

Something wacky is going on here. That x-over makes absolutely no sense. :scratch2:

Can you tell if the drivers are 4ohm or 8ohm, or even 16ohm?

 

[drspiff]

I was tracing the lines for the XOVR and I have been known to make a mistake in topology... Let me look again and see if I really have it right. The speakers have no indication of impedance. And an ohm meter is next to useless for this.

BTW cablephil212, is your chair made out of cake?

 

[cablephil212]

No. It's recycled cardboard.

Some tree hugging company was selling them. Can't see it being too comfortable. Cool to look at, but to sit in? I don't think so.

 

[cablephil212]

I was tracing the lines for the XOVR and I have been known to make a mistake in topology... Let me look again and see if I really have it right. The speakers have no indication of impedance. And an ohm meter is next to useless for this.

BTW cablephil212, is your chair made out of cake?

The x-over layout looks OK, but I am questioning the parts values. That's why I asked if you knew what ohms the drivers are.

Why is a meter useless for that? It should tell you what the DCR is.

 

[drspiff]

I thought you had to use some VTVM while the speaker was under a 1KHz wave or some such nonsense. As for the values, the cap I cut out is a 3mfd 50wvdc 85degrees C. And the pot is a Clarestat 30ohm. I'm assuming the inductor is 2.25mH because written in ball point on the wrapping is "2.25". I suppose it could be 2.25H but that seemed a little large.

Would it make more sense if it was 2.25H?

The DCR for the woofer is about 5ohms and the tweeters about 12.3ohms.

 

[cablephil212]

I thought you had to use some VTVM while the speaker was under a 1KHz wave or some such nonsense. As for the values, the cap I cut out is a 3mfd 50wvdc 85degrees C. And the pot is a Clarestat 30ohm. I'm assuming the inductor is 2.25mH because written in ball point on the wrapping is "2.25". I suppose it could be 2.25H but that seemed a little large.

Would it make more sense if it was 2.25H?

The DCR for the woofer is about 5ohms and the tweeters about 12.3ohms.

NO. A 2.25H would be sooo huge. About the size of a beer can.

So the woofer is probably 8ohms, and the paralleled tweeters are 16ohms.

A 2.25mh coil on an 8ohm driver will block everything from (about) 600hz and up. A 3uf cap on a 16ohm driver will block everything below (about) 3K. Both are 6db (1st order) slopes. Even with the driver roll-off, that's a huge gap between the woofer and tweeter. That's why I asked for the impedance of the drivers.

They might not be the original x-overs. Still makes no sense with those values.

I would try running the woofer full-range. Use a jumper to attach the 2 leads on the coil. That will by-pass it, and the woofer will get the full signal from the terminal plate.

Give that a try, and see how it sounds.

 

[drspiff]

The modified speaker is less "boomy" than the unmodified speaker. So I think I'm moving in the right direction. Thanks for your help. I'll listen to these for a while and see how they feel in the morning.