[Ricci]

Aceinc,

Keep the data coming. Can you do FR measurements? I'm really interested in the upper end response where all of the nasties are in the models.

McCallister,

Yes a low tuned TH for an 18" or 2 12" is going to be huge. Probably way bigger than a huge low tuned ported alignment.

 

[myn]

Thanks for the info on your cutting process. If this project deams sucessful it sounds like it may be a pretty easy build for people who follow your lead. We all appreciate all of the hard work and testing you've done so far.

On another note. Do you happen to have any pics of the SPUD with the top on now? Would love to see how she looks!

 

[aceinc]

I should be able to do FR graphs ala REW, but that will have to wait until Saturday.

I am at the office right now, I will try to get a few more pics with the top on. It is standing in my living room and looking rather large. My wife is rather understanding as long as I promise it is not permanent. Don't expect beauty, as I am not a cabinet maker.

Paul

 

[DrWho]

How are you bracing the internal panels?

 

[Allanf714]

Great idea Paul. I'm anxiously awaiting measurement data on this project. If you're successful at cloning the spud, I suspect a lot of people will follow suite.

Let's see: Potential world class performance and you can build a pair + amplify them both for maybe $700-800.

I had a couple of questions though. Why did you change the original 60 degree angle on the second driver?

I see in another thread... that there does appear to be some degree of dampening material utilized in the real unit..... are you planning on using any?

Allan

 

[mcallister]

Can't wait to see some results on this build. I wonder if Danley gets upset about these types of threads? Since it appears the designs were "leaked"?

 

[aceinc]

Regarding bracing, I did not put in any bracing, but based on the limited testing I have done I would add two braces, one along the long external panel heading away from the drivers, and the second heading down the long side after the first bend. The rest of the cabinet seems fairly vibration free even under heavy load.

I might be wrong on this but the internal panels should be pressurized from both sides at the same time and wouldn't need bracing.

The reason I didn't do the 60 deg. driver mount was I did not believe it would have any effect on the sound, and the drivers I chose are relatively shallow so they fit in the space with what I feel is enough room for breathing/cooling. That combined with the fact that it made construction much simpler.

I did not put any damping material in, I might put some material in behind the drivers, but I have none now. I went back and forth on this but decided in the end to not put any in.

Paul

 

[myn]

I see in another thread... that there does appear to be some degree of dampening material utilized in the real unit..... are you planning on using any?

Allan

Which thread? Are there any pics to the extent of dampening and location?

 

[Allanf714]

I noticed the dampening material right here.
http://forums.audioholics.com/forums/showthread.php?t=49678&page=8

Of course this picture doesn't tell us as to whether it's present throughout the enclosure or just adjacent to the drivers.

Paul, are those drivers wired in or out of phase from one another?

 

[myn]

You going to test both the Trio8's and the WB-740P's?

 

[aceinc]

The drivers are wired parallel out of phase.

If the Trio 8's fall flat on their face, I may try the W8-74p's.

My thoughts on dampening for this enclosure would be to control harmonics, and other anomalies outside of the intended frequency range of the cabinet. If properly crossed over with a steep low pass filter I feel that there shouldn't be much additional that dampening would provide, and there is the possibility that it could/would reduce the overall efficiency of the cabinet.

Were I truly prototyping this cabinet in preparation for production I would do a lot of things differently, starting with making many of the panels removable. This would allow fine tuning in bracing and dampening without building multiple prototypes.

My purpose however, is to prove to myself whether there is something "magical" about a tapped horn. I chose the TH-SPUD because it seems unlikely that you could get room shaking 20 hz bass out of two 8" drivers, whereas a 12" or 15" decent driver in properly designed enclosure can do this. So putting one or more 12" - 15" inchers in a Tapped Horn wouldn't prove as much to me.

I might not be doing any of this if I had been able to get into Danley Sound Labs. Over the summer my family and I were taking a driving trip from S Florida to S Florida via Mt. Rushmore. We all chose things we wanted to do, and I chose stopping by Gainesville Ga. on the way back south. Well, we stayed in Helen Ga., on a Sunday night and early the next morning I called DSL, and to my chagrin they had no one available to do a demo that day. It was my fault as I hadn't called a few days in advance, but I didn't realize I needed to.

At any rate I was bummed:hissyfit:, and I have been scheming of how I was going to satisfy my curiosity, so here I am building this TH-SPUD clone. As luck would have it, my wife will be on the other side of the state this Saturday, so I'll be able to play all day without interruption.:yay:

I'll try to keep everyone posted on my progress.

Paul

 

[myn]

What did you decide on the damping? felt? Polyfill? or ? and where did you apply it? The entire horn structure or just behind the drivers?

Was the reason you didn't arch at 60 degrees because the drivers you choose could actually fit, unlike bulky the TangBand 740Ps which would butt their magnets against the enclosure?

I'm very anxious to see how your testing goes this weekend. I'll be very interested to see how it performs against your current array of subs.

Do you have an SPL meter and REW handy?

 

[aceinc]

I have a radio shack digital SPL meter, REW, as well as a behringer ECM microphone, and small mixer.

The other questions I think I covered in previous posts.

Paul

 

[myn]

This look like polyfill? Almost looks quilted.

 

[Allanf714]

Re: dampening

OK, based on the one pick posted over at Audioholics.... it appears as if the real SPUD does have polyfill or batting quilted on at least some surfaces. This shows the driver opening at the origin of the horn.

http://forums.audioholics.com/forums/showthread.php?t=49678&page=8

Now, based on the pick posted above..... we see additional dampening material (quilted or stuffed, not sure) located at the mouth of the horn (the opposite end of the horn but the other side of the drivers). Is it safe to assume that they used some degree of dampening material throughout? Perhaps they used a quilted layer throughout, much like we would in a ported enclosure.

Allan

 

[aceinc]

Had I seen the last picture posted by Myn before I sealed the cabinet up I might have changed my mind about dampening.

It's a bit late now for me on this cabinet, but others can certainly learn from this.

BTW myn, where did this picture come from? Are there additional pictures posted on the web?

Paul

 

[myn]

I found them in RMK's PhotoBucket stream:

http://i110.photobucket.com/albums/n86/rmk_01/

 

[myn]

Can't wait to hear the results

 

[aceinc]

I am starting to test with REW. I have a RS Digital SPL Meter as my Mic. I have a NAD 2200 amp in bridged mode for the amp and a toshiba notebook with an internal realtek sound card as my source.

Initially I will be testing in my living room which is 15.5' x 26' x 9' with various pieces of furniture, a fireplace and openings into the rest of the house.

What kind of tests should I perform?

My first test I thought to perform is to put the Mic about 2" away from the mouth of the horn sitting on a pillow.

What else would folks like me to do?

Paul

 

[myn]

It appears the TH-SPUD was originally designed for almost near field listening position. To be placed under a couch or behind it near the listener. As Danley describes it the "Horn Bubble".

I am pretty sure its pretty heavy but I wouldn't mind seeing some plots of how it sounds in different positions. Corner loaded, front (at least 8 feet away from listener), Behind (3 feet or less away from listener (horn bubble).

A MAX SPL plot too if you can. And I would really value your impression versus your other subs.


Again we really appreciate all of the effort you've put into this project thus far. I'm really looking forward to the results.

Edit: Reading more from Danley about positioning:

Try placing the outlet for each spud in the outer corners with the box moved into the wall / wall corner. This produces an acoustic mirror for the box by being up against the corner and raises the efficiency and lowers the low corner.