[jparkhur]

TT asked for this I think.. to see proportions.. That is a MFW 15 behind it.. This shoudl help.. Small foot print.  Big on sound!
Jon Parkhurst

[Guy 13]

Hi all Audio Circle members.

Small it is, but will it be BIG on sound?
Sure hope so !

Guy 13

[Danny Richie]

Hi Danny and all Audio Circle members.

I don't remember where I got this sketch,
but what do you think about it?
Do you think it will work taming the Dayton PS220-8?

Guy 13

The first part of the circuit is for baffle step correction. The value of the inductor depends on the baffle width and the resistor level depends on how hot the top end is. Typically inductor values around 1.0mH to 1.5mH are used, and resistor values between 3 ohms and 5 ohms. A 12 ohm resistor presents a huge amount of attenuation of the top end.

The LCR or notch filter is used to reduce a peak in a give range. The values used will attenuate a very narrow range centered at 3.5kHz. That is right where that driver has a pretty big peak. So that's good.

[skalos]

I like the whole idea regarding this speaker, in that, experimenting with new ideas pushes the state of this art/craft/industry.

Woofer questions.

Why the U-shaped cabinet for the dipole woofers vs. the typical H- shaped cabinet that seems to be preferred?

How will the sound be different 1 vs the other?

How was the length of the legs in the U determined to be appropriate for this setup?

Lastly, in the V series the front of the H frame is in the same plane as the coax drivers where in this setup, the plane for the drivers they are bolted to is the same, how is time alignment affected by this?

[HAL]

Mechanical time alignment can be done with signal time delays in the digital crossover.  The time step size is 5.2 microseconds.  This means that the signal can be electrically altered in 0.071 inch steps between the full range driver and servo woofers.

You can align them just about anywhere you like electrically with the time delay capability.

[skalos]

Mechanical time alignment can be done with signal time delays in the digital crossover.  The time step size is 5.2 microseconds.  This means that the signal can be electrically altered in 0.071 inch steps between the full range driver and servo woofers.

You can align them just about anywhere you like electrically with the time delay capability.

I understand. 

Does your plan include this alignment for this driver above this woofer in its current state, or will it be available to the end user to calculate and make the adjustment in their environment?

I personally believe that it should be done in the crossover because all the parameters for each driver, woofer, and "box" are known at the time the crossover is being designed.  Am I correct?

[HAL]

Yes, it will be time aligned by me in the XO before shipping. 

It will be plug-in and listen.

[HAL]

The new driver burn-in system is running with the two Dayton drivers. 

Will give them a few day's of work out and start some measurements.

[archeion]

looking forward to hearing more.
too bad we have to wait...

[HAL]

Yes, I am in the same boat as everyone. 

Waiting is always the hardest part!

[jcotner]

Mechanical time alignment can be done with signal time delays in the digital crossover.  The time step size is 5.2 microseconds.  This means that the signal can be electrically altered in 0.071 inch steps between the full range driver and servo woofers.

You can align them just about anywhere you like electrically with the time delay capability.

I assume that you have factored in the additional processing latency on the full range so when this offset is
zero you automatically add in the correct sample delay so the sub output is delayed to coincide with the
full range calculation output.
Ideally your calculation chain on the full range would take some multiple of 1/192KHz to complete.
Just saying.

[Rclark]

They do look pretty sweet. Keep it rollin' fellas.

[HAL]

I assume that you have factored in the additional processing latency on the full range so when this offset is
zero you automatically add in the correct sample delay so the sub output is delayed to coincide with the
full range calculation output.
Ideally your calculation chain on the full range would take some multiple of 1/192KHz to complete.
Just saying.

Yes,
The software development code lets me benchmark the times in the processing chains and then I can apply the correct offset for the other channels.

[Mmaxed]

This project is interesting as I have been thinking about playing around with OB.  Have a couple of questions.

The Qts of this driver is listed as .30.  I was under the impression that higher Qts  of .6-.8 was better for OB/

How much does he circuit posted by Guy 13 change the sensitivity of the driver?

[ebag4]

This project is interesting as I have been thinking about playing around with OB.  Have a couple of questions.

The Qts of this driver is listed as .30.  I was under the impression that higher Qts  of .6-.8 was better for OB/

Higher QTS values are important if you are trying to get bass from an OB driver.  Since this speaker is using the servo subs to generate bass there is little need for the Dayton driver to have a high QTS.

Best,
Ed

[Danny Richie]

This project is interesting as I have been thinking about playing around with OB.  Have a couple of questions.

The Qts of this driver is listed as .30.  I was under the impression that higher Qts  of .6-.8 was better for OB/

How much does he circuit posted by Guy 13 change the sensitivity of the driver?

A higher Qts is more ideal, but not an issue in this application since the full range driver won't see any really low frequency information.

[S Clark]

A higher Qts is more ideal, but not an issue in this application since the full range driver won't see any really low frequency information.

If you aren't sending any low frequencies to the full range, why use an 8"?  Aren't there 4-5" drivers out there that would image better and react faster than an eight?

[HAL]

Scott,
One of the ideas is to start with the Dayton full range driver and then try other units. 

jparkhur is making inserts for the 8" mounting hole that will let smaller drivers be adapted to the baffle.

Since I have to measure every driver to do this, the concept lends itself to being flexible.

 

[archeion]

I was wondering that as well, but had decided to just wait until we had more measurements.  Sounds like it could be amazingly versatile.

[jparkhur]

As everyone has certain drivers they like, the master plan is to allow the end user to pick and choose the upper driver themselves.  The Dsyton 8, as has been said, shows a good starting point and proof of concept. You could choose to have an 8 inch hole cut or stick with one specific to your driver. I made blanks for myself and have put in a Fostex FF125WKeN and 85WKeN, the later has great top end but in OB can't really get down far enough.  The 125 is good and I threw my TB. 1808 in also. This has a higher Q to start with but still has 14 db of play at the top that would need to be taken care if. Think of it as the Sizzler, you pick all the pieces and make the best loudspeaker for yourself.  As well, it will be flat across the board