[Vapor Audio]

Hey Danny, just wondering what would be better for midrange duty in a 3-way - M130 or M130x?  I'm leaning toward the regular 130 because of the extra sensitivity, and it'll only run approx 500hz - 2500hz, so xmax shouldn't ever be an issue.

[Danny Richie]

The standard M-130 will be fine. I am still waiting on a delivery date for the X model.

I have also used the M-130's in several 3 way designs. The big no,no would be to cross them over to some dissimilar larger driver right in the heart of the mid-range, and 500Hz is the heart of the midrange. Keep your crossover point to the 200Hz range or less and it will sound much better.

[Vapor Audio]

I'm impatient, planning on calling you tomorrow to talk about it ... but I'm spending my weekend modeling out ideas 

So the idea I'm thinking is 3 way with a GR-T2, single M-130, and a pair of M-165x.  I'm going to bi-amp, and can actively cross - probably active low-pass the pair of 165x's and active high-pass the 130 midrange.  Then passive in-between the 130 and T2.  So I'll be able to adjust levels between the top and bottom if needed.

I already have the T2 and the pair of 165x's running in a 2.5 way, but am of the opinion that using a 165x for baffle step .5 duty is a total waste - the drivers don't need much baffle step at all due to their natural response.  And the hope is with a dedicated mid I'd gain a touch more clarity and detail, and cross to the tweeter around 2500hz (1800hz right now), which some help it perform better as well. 

I can give the 130 about .3 cu/ft sealed, and the pair of 165's about 1.3 cu/ft - vented, passive radiator, sealed, whatever.  I'm thinking of trying a side-mounted passive, but don't want to cut the hole for that unless it's a good idea

So whatcha think, is the idea worth trying?

[Danny Richie]

So the idea I'm thinking is 3 way with a GR-T2, single M-130, and a pair of M-165x.

It's a great idea.

I'm going to bi-amp, and can actively cross - probably active low-pass the pair of 165x's and active high-pass the 130 midrange.  Then passive in-between the 130 and T2.  So I'll be able to adjust levels between the top and bottom if needed.

That will work well too.

I already have the T2 and the pair of 165x's running in a 2.5 way, but am of the opinion that using a 165x for baffle step .5 duty is a total waste - the drivers don't need much baffle step at all due to their natural response.

Yes, the natural response curve of the M-165X drivers already compensate for the baffle step loss.

So whatcha think, is the idea worth trying?

Do this and I will guarantee great results. Build the A/V-O and put the M-130 in a long V shaped sealed enclosure of about .2 cubic feet. Then mount the two M-165X woofers firing to the outside and you can vent those as needed. Cross the M-130 to the M-165X woofers in the 150 to 200Hz range and no higher.

I will be glad to send you the passive network for the M-130 and GR-T2 tweeter for just the cost of the parts.

This design images like you won't believe and is more transparent than anything else you can go with it. It is highly recommended.

http://www.gr-research.com/kits/avo.shtm

See measured data here: http://www.gr-research.com/kits/avomeasurements.shtm

[Vapor Audio]

Do this and I will guarantee great results. Build the A/V-O and put the M-130 in a long V shaped sealed enclosure of about .2 cubic feet. Then mount the two M-165X woofers firing to the outside and you can vent those as needed. Cross the M-130 to the M-165X woofers in the 150 to 200Hz range and no higher.

I will be glad to send you the passive network for the M-130 and GR-T2 tweeter for just the cost of the parts.

This design images like you won't believe and is more transparent than anything else you can go with it. It is highly recommended.

http://www.gr-research.com/kits/avo.shtm

See measured data here: http://www.gr-research.com/kits/avomeasurements.shtm

Those AV-O's certainly look like something fun to try in a the near future, but I can't do it with this project simply because the cabinets are already made, and I wouldn't be able to modify them as needed for the top mounted woofer and chamber.  I think those might be perfect for a bedroom speaker to replace my Wharfedale Evo 30's.

My worry about crossing so low is doing baffle step with the M130 - which will lower it's effective sensitivity.  Can I get away with no baffle step on a 8" wide x 40" tall baffle you think?  And what do you think about using a 10" or 12" passive radiator with the 2 M-165x? 

[Danny Richie]

My worry about crossing so low is doing baffle step with the M130 - which will lower it's effective sensitivity.

If you up fire the M-130 on a baffle this small you don't have baffles step loss to contend with. The baffles step loss begins near the crossover point. All of its output is after the loss of any baffle re-enforcement because there is no baffle re-enforcement. You get 87db sensitivity.

Can I get away with no baffle step on a 8" wide x 40" tall baffle you think?

What you get is an uneven step loss. It starts at 800Hz in one plane and at 500Hz in another.

And what do you think about using a 10" or 12" passive radiator with the 2 M-165x?

 

A PR will work fine with them if there was any chance of finding one that would load and tune the box properly. I don't know of any.

...but I can't do it with this project simply because the cabinets are already made, and I wouldn't be able to modify them as needed for the top mounted woofer and chamber.

Bummer, this design works really well.

[Vapor Audio]

If you up fire the M-130 on a baffle this small you don't have baffles step loss to contend with. The baffles step loss begins near the crossover point. All of its output is after the loss of any baffle re-enforcement because there is no baffle re-enforcement. You get 87db sensitivity.

Sorry, I've tried reading this about 10 times and I don't get what you're saying. 

What you get is an uneven step loss. It starts at 800Hz in one plane and at 500Hz in another.

Right, I understand that with my baffle dimensions.  But the 130 response curve doesn't seem to automatically mitigate the effects of baffle step like the 165x does.  Am I right or wrong there?  If I'm right, I need to do some baffle step in the xover for the 130, which from my experience will lower it's effective sensitivity.

Sorry if I'm missing something obvious here ...

A PR will work fine with them if there was any chance of finding one that would load and tune the box properly. I don't know of any.

I thought tuning a PR was just about keeping cone area and mass close, and then tuning it with weights. 

Bummer, this design works really well.

Oh, there will be more projects in the near future.  I have been thinking of doing something open baffle, AV-O looks fun too and will probably work with my room better.  But I'm a huge fan of dynamics, that'll be my only concern.

[Danny Richie]

Sorry, I've tried reading this about 10 times and I don't get what you're saying. 

I mean that with the up facing woofer you don't see a baffle step loss in the response. By the time the woofer plays high enough in frequency to show a baffle step loss it is also high enough in frequency that you are too far off axis to get it. At above 2kHz it has transition from omni to direct radiating. Then it crosses to a tweeter before it is allowed to play any higher. 

But the 130 response curve doesn't seem to automatically mitigate the effects of baffle step like the 165x does.  Am I right or wrong there?

If you use the M-130 under the GR-T2 tweeter and have a pair of M-165X underneath it then you really don't have to compensate for much baffle step loss to begin with. Just has you start to loose output from the M-130 you can allow the M-165X speakers to start to catch it. Let them cross in the 200hz range with a low order roll off and you won't have much to compensate for if any at all.

I thought tuning a PR was just about keeping cone area and mass close, and then tuning it with weights.

You have to also calculate the Vas of the PR, suspension, air sweep, X-max... If you can port it, I would. It will be much easier.

[Vapor Audio]

Thanks for the explanation Danny, that makes perfect sense ... I didn't realize you were talking about the AV-O in that one statement that I said I didn't understand.

I'll go simple with the port then, I just like trying stuff different   

[Vapor Audio]

Just an FYI Danny, the center I did with a pair of M-165x's and a T2 came out great on the first crossover attempt.  It absolutely slams - incredibly dynamic - and sucks up every bit of the 150 watts I'm giving it.