Need Advice

[TheWarrior]

In short, I bought 2 UPA-1's run through an XDA-1 and can very clearly hear the shortcomings of my RBH WM-30's.

I could blow up to $3k on new RBH/Status book shelves, or I could construct my own. The idea of this project has be raring to go!

The Statement Monitors seem to be a perfect replacement. I understand their driver complement is not of Status Acoustics quality, but should provide enough of a difference to keep me happy. My issue is that I would want to modify the cabinet to be Wall Mounted.

As I understand it, the simple fix would be to make this a sealed cabinet and just beef it up a bit in the rear to support the weight. Am I correct with this, accepting that I will have slightly decreased frequency response? Or is this a question for Curt?

Would there be any appreciable difference if I increase mass loading or even go so far as to eliminate parallel sides in the cabinet's structure? I don't mind the extra carpentry.

Thanks!

 

[agarwalro]

First and foremost, the vent corresponds with a transmission line port for the mid speaker. Blocking the port changes the tuning (how, I can't say). Additionally, no crossover design is provided for BSC corresponding with on-wall placement.

If someone can address these two concerns, you might have a Statement Monitor On-Wall design .

 

[TheWarrior]

Could I build a shelf for the speakers, yes. Do I want to, No, not really. So I think I will conduct some extensive research, give myself a crash course in cross over design, and figure out what to do.

Now that you're telling me I can help create a new version, dude, I'm there!

 

[TheWarrior]

Further study has got me even more excited, but has also made me realize how much learning I need to do.

Ordered the Loudspeaker Design Cookbook. If anyone has any other recommendations, please!

 

[agarwalro]

DIY Audio & Video - FAQs, Tutorials, and Calculators for Speaker Boxes, Crossovers, Filters, Wiring and more

Left frame has calculators (below ads).

 

[Swerd]

The Statement Monitors seem to be a perfect replacement. I understand their driver complement is not of Status Acoustics quality, but should provide enough of a difference to keep me happy. My issue is that I would want to modify the cabinet to be Wall Mounted.

As I understand it, the simple fix would be to make this a sealed cabinet and just beef it up a bit in the rear to support the weight. Am I correct with this, accepting that I will have slightly decreased frequency response? Or is this a question for Curt?

Would there be any appreciable difference if I increase mass loading or even go so far as to eliminate parallel sides in the cabinet's structure? I don't mind the extra carpentry.

I don't think this design could easily be modified into being wall mounted.

There are two "ports" involved in the Statement Monitor cabinets. One is a 2" diameter flared port tube that is tuned to about 34 Hz with the RS-180 woofer in the 24 liter cabinet. If it is eliminated, the cabinet volume that the woofer "sees" would have to be different, and I suspect, much larger. A sealed bass alignment will probably not go as deep as the 34 Hz for the ported design.

The midrange driver is mounted in a separate compartment, a tube open at the back. Having a partially open-backed midrange is the key design feature of the whole Statement series of speakers. Closing that would significantly change the design, and risk loosing the best feature of this design.

All this may be possible, but you should ask Curt Campbell about this.

 

[TheWarrior]

I don't think this design could easily be modified into being wall mounted.

There are two "ports" involved in the Statement Monitor cabinets. One is a 2" diameter flared port tube that is tuned to about 34 Hz with the RS-180 woofer in the 24 liter cabinet. If it is eliminated, the cabinet volume that the woofer "sees" would have to be different, and I suspect, much larger. A sealed bass alignment will probably not go as deep as the 34 Hz for the ported design.

The midrange driver is mounted in a separate compartment, a tube open at the back. Having a partially open-backed midrange is the key design feature of the whole Statement series of speakers. Closing that would significantly change the design, and risk loosing the best feature of this design.

All this may be possible, but you should ask Curt Campbell about this.

I was anticipating this. I contemplated both a sealed, and a larger standard cabinet size so I could channel the port tube off to the side away from center.
It would be very complicated on the carpentry side and may require a different size port. I'm also comparing the differences in the crossover design of the near and far wall applications they have.

To respect Curt's time, I won't contact him until I have more knowledge of such things and a clear design with clear questions to ask.

 

[Swerd]

I was anticipating this. I contemplated both a sealed, and a larger standard cabinet size so I could channel the port tube off to the side away from center.
It would be very complicated on the carpentry side and may require a different size port. I'm also comparing the differences in the crossover design of the near and far wall applications they have.

To respect Curt's time, I won't contact him until I have more knowledge of such things and a clear design with clear questions to ask.

I had missed the part about the near-wall and far-wall versions.

All of the Statements series designs are to be listened to off axis and positioned pointing straight ahead with 1½" (is that 1½' or 1½"?) of distance from the back of the speaker to the wall behind them. They will work surprisingly well closer but further out is better. The Monitors have gone a step further. Curt waved his magic wand and created not only a far wall version that is designed to be used out into the room, but also a near wall version that can be used as close as 12" from the wall to the back of the cabinet. In addition, he designed a 'switchable' crossover version that allows complete flexibility of placement by inserting a switch on the back of the cabinet that selects the proper crossover.

A new twist this time is a crossover network optimized for Full BSC and for Partial BSC, as well as a 'switchable' version that allows the selection of either crossover at the flip of a switch. The difference between the two circuits results in about 2 dB increased sensitivity for the nearwall version above a couple of hundred Hz.

Was that 1½" a typo? It makes more sense to me as 1½' (18").

It seems that you could side or bottom mount the port tube for the bass driver as long as you keep the internal cabinet volume the same. The BSC for the near-wall version should work OK for you.

But the near-wall version still assumes a minimum of 12" space between the rear of the cabinet and the wall behind it. If you make that 0", you will lose the rear wave from the midrange driver and any possibility of increased sound field depth. The beauty of the Statements' is that the open tube behind the midrange lets you vary the amount of polyfil stuffing, and as a result, you can vary the balance between the midrange front and rear wave.

This is similar to the Salk SoundScape and Philharmonic speakers. According to Dennis Murphy, hearing the original Statements inspired him to develop those other designs. It was the variable sound stage depth that impressed him.

Your questions for Curt Campbell should be:

1. Is the BSC (baffle step compensation) for the near wall version enough if you wall mount the speaker.
   
2. Will the band pass filters for the midrange be OK as they presently are, or must they change if you close the back of the cabinet and mount it on a wall.

 

[TheWarrior]

Ok, The Cookbook has arrived and I have already plowed through it. Given my listening space, and need to wall mount, and complete desire to plow head first in to this..... I have decided that I am going to construct my own wall mounted, sealed, two way speakers. I will utilize Scanspeak/Accuton drivers to create as close to a full range set up as I can. Thanks to the Cookbook, I'll be able to choose the best possible woofer for my application.

Major points I still need to address are:

Cabinet design: the tweeters will be above the listening position, should I still build the woofer enclosure to extend outward 1-2" to account for time delay and blend the drivers Frequency Response(so far, I plan to use a 3rd Order Butterworth) Also, I am wanting to keep the cabinet fairly shallow, and compensate for this by making the cabinet wide, I need to plug some values in to these calculators and see what happens

Driver/Crossover choice: Obviously I'm feeling daring and wanting to go big my first time out... thankfully I have a good friend who is an electrical engineer who can double check my crossover design before I could pose any damage to high end drivers. The Cookbook provides the info I need to select a woofer that will perform well in a sealed cabinet, I hope to then find a tweeter that has similar sensitivity to make my life easier. Looks like both will be 4 ohms either way, so at least that part is answered. I am (so far) choosing the 3rd order Butterworth because it will provide a good slope, make it pretty straight forward to choose a crossover frequency, and it appears to be mathmatically (90 degree) certain that I need to reverse polarity of the drivers(when wired parallel) so I can eliminate the guess work.

Damping: Need to gain a better understanding of this concept in order to make good product choices, and therefore design choices in the cabinet.

These aren't so much questions as they are me thinking out-loud. Seems like this group is a good place for support and knowledge, so I will definitely keep you all up on my design as it progresses in exchange for pretty pictures of my work once it begins!

 

[agarwalro]

Why not dump the passive crossover for a DCX 2496 or Mini DSP?

 

[TheWarrior]

What? Did you just take all I wrote, which was all info absorbed from one read through of the Cookbook, and tell me the money spent on the book could have gone to a gismo that does it all for me? Where is the fun in that!?

That is cool, I had no idea (which I guess I should have figured) that all of this could be done in the digital domain. But, excuse the reference, I feel like the only way to make my journey complete, is to construct my own lightsaber...

 

[agarwalro]

What? Did you just take all I wrote, which was all info absorbed from one read through of the Cookbook, and tell me the money spent on the book could have gone to a gismo that does it all for me? Where is the fun in that!?

That is cool, I had no idea (which I guess I should have figured) that all of this could be done in the digital domain. But, excuse the reference, I feel like the only way to make my journey complete, is to construct my own lightsaber...

Lol! If anything, I'd say the cookbook is creating a good foundation of concepts. Additionally, it is easier to screw up active networks because there is a tenancy to overcorrect, so having clarity in the basics is crucial. That said, active crossovers are a walk in the park once you're able to design passive ones and when done right, will be miles ahead of the best passive crossovers.