[Squibby]

as promised......







any questions, please do not hesitate to ask.

[Odal3]

Squibby,

I remember your development picture, and the intricate solution of plasti-dipped cords . Thanks for sharing the end result. Looks really nice!!!! Very creative.

So if I get the pictures right, the frame on the top and bottom are glued (?) to the panel all the way from side to side, while the bars accross do not touch the panel. Did you ever play the board without the frame attached? Based on my humble experiments, I found that if I add a thin wood bar side to side on the edge like that it makes it almost too stiff and reduce the output below 200hz. (just for the record, my attempts are not even close to how nice your wood work is, so I might just have screwed something up    ). I wonder if this doesn't let your panel vibrate enough to get enough bass. Similarly to OB_Newbie, I also get some really nice deep bass on my birch boards (but I still add a sub for the really low tones).

Couple of questions: Did you hear any difference before and after adding the shellac? Did you stain them first?
Did you hear any difference from playing them freestanding vs. attaching them to the wall?

[Odal3]

If someone is interested in NXT's own presentation of the DML technology: https://simeoncanada.com/wp-content/uploads/RandI3.pdf

Many examples of various applications, and plots. Plus, a long summary list of papers etc. in the back.

[Squibby]

Hi Odal3,

i tested the panel before and after adding shellac but its hard to evaluate exactly what the difference is, as when i tested without the shellac, the exciters were brand spanking new and didnt have the break in time that they got when the shellac was applied.

The frame itself is very light, made from spruce and of course could be improved further by perhaps making some stylized holes throughout it. the frame only touches the panel along the top and bottom (glued) and gives the panel a slight curve along the horizontal...not sure if this adds anything to the dispersion of the sound, but it does hide the guts and the back of the panel. the side bars do not touch the panel (only the top and bottom of the frame) but because the entire frame is suspended it acts as one with the panel as a kind of bracing. i do think that reducing the number of suspension points will also improve the sound and bass and allow the panel to move more freely.

The wiring of the exciters on the back of the panel did pose a problem at first and i was getting alot of distortion at high volumes.....it turned out that the wiring was vibrating too much and in some cases enough to crack the solder. I solved this by covering each and every wire connection with sugru....turned out to be ideal.

bass output is sufficient with most types of music but is noticeably absent with modern synthesized music. I'm hoping that the next iteration of this panel which will be considerably bigger will solve that issue.....i'm planning to make a few more for friends once i've finished working on my house and have some more time available to tinker around.

The sound is surprisingly good given what it is and people who have heard it are quite astounded that a little bit of plywood can produce such clean clear music.

the entire objective for me was to create a kind of musical instrument/hybrid speaker with as small a footprint as possible, yet which looks nice enough to not be hidden in the corners of a room as happens with so many conventional speakers.

i had the speaker on a temporary stand while i was working on it and i have to say that the sound was slightly cleaner in my opinion, but i think thats more to do with the proximity of the wall to the back of the speaker.

I dont have any specialized measuring equipment to give any kind of info regarding frequencies etc......just my ears.

Is it good enough?......definitely.

can improvements be made?....absolutely. only a little more experimentation will tell.

all the best,

Squibby.

[OB_Newbie]

Hey Squibby,
I remember these too!  They turned out really nice indeed but had no doubt they would given the nice construction!

I'm fascinated by these wood panels.  Do you have a iPhone/smartphone that you can use to get some RTA measurements with?  I'm listening freestanding mostly and curious what impact the frame and suspension has on the response of the panel.  I'm not sure what direction I want to go next with my ply panels and seeing what response you are getting might give me a bit more to run on.

Fantastic work!  They are beautiful... 

[OB_Newbie]

More NXT reading...  http://www.tectonicaudiolabs.com/library

[Odal3]

Looks like a lot interesting stuff in both the link I posted as well as this one - too bad most of it are behind pay-walls.

Squibby - thanks for the update. Your demo stand actually looks really nice as well. Looking forward to hearing more about your experiments after you are done with the house.

[Squibby]

hey OB_Newbie,

I do have a smart phone...if you can recommend an app to take some measurements with, together with a track or two (so that we have a reference) then i will take some measurements as soon as i can.

Thanks in advance,

Squibby.

[Squibby]

Hey Odal3,

Thanks for the kind words......i abondoned the stand because as my wife correctly pointed out it does make our living room look like a basketball court without the net!

Squibby.

[OB_Newbie]

Hey Odal3,

Thanks for the kind words......i abondoned the stand because as my wife correctly pointed out it does make our living room look like a basketball court without the net!

Squibby.

Hey Squibby,
For a free RTA, "RTA Lite" works.  But for $5 "Audio RTA" is a big step up from RTA Lite's 1/3 octave to a much better resolution of 1/12th octave bands.  Very useful tool for $5.

I use "Tone Gen Pro" for source signals... mainly pink noise for use with RTA.  I use the sweep function too along with the free "SPL Meter" app to get measurements at certain frequencies and freq. spans (I plot out the freq. resp. on paper sometimes).

Fun stuff for little to no money!

I got the Dayton Audio iMM-6 Calibrated Measurement Microphone for iPhone along with Audio Tools... its a pretty accurate once the mic is calibrated using Audio Tools app.

Good luck man!     

[Squibby]

Hey OB_Newbie,

did a sweep (various times and with a couple of different apps) with a frequency generator and this is what i got.... no idea what any of it means or if i even did it right...please forgive my ignorance....hopefully you'll be able to translate what this all means....i only assume that a flatter response is better!.














all the best,

Squibby

[Odal3]

I have no experience using the iPhone based apps, so cant answer specific questions. Plus, I'm new to this as well so take the following with a grain of salt.

Read the dbfs scales as relative to each other at different test frequencies. Yes, most strive for flat curve, but you will never get close to a completely flat line in an untreated room and there will be some dips and peaks due to room response. The trick is to minimize them in the range you are interested in. With that said, the diffused sound of the panels is not as sensitive to the room as a standard box speaker is.

A 10 db dip will sound thin in that frequency range.
To see the dip and peaks, see if you can play around with the smoothing. Looks like the pics you have are set at 1/6. Many published specs for commercial speakers use 1/24 and they target a plus minus 3db difference accross the whole frequency band. I normally use 1/12.
Can't tell what is really measured on the plots since they are not really consistent, but if guessing here, the white line in your first plot indicates about 10 db drop around 200hz, and that you will barely hear anything lower than 100hz, which is consistent with my measurements when I have a frame attached to the panel on two or more sides.

When measuring, make sure you are consistent: same distance, same volume, same angle of mic, same left,middle,right offset from speaker.
Btw: be careful with your ears when running test tones. The high frequency tones doesn't sound loud but can really hurt you. If running moderate or louder test tones, wear ear protection.

[OB_Newbie]

Thanks for the measurements Squibby, appreciate it!
Like Odal commented the 1-2 and 3-4 are different but the 3 and 4 pics do look similiar to the measurements we have made.  Looks like ample bass and reduced high frequencies.  But smooth from 1K to 10K.

Speaking of measurements and frequency responses....  for what its worth, for the last week I've been EQing my panels over their entire range and they sound noticeably better.  Still tweaking but it is becoming more clear, to me anyway, that EQ will be a valuable tool to get a more balanced panel response.

[Odal3]

Btw: do you still like the Ultra exciter. Did you get the one that broke replaced?

I have been playing more with different attachment options inspired by the thesis and I found a way to hold it from the side without touching either the front or backside or the transition to the edge. This is giving me my best result yet. I will do a more detailed writeup once I have taken some measurements since the ones I took looked weird since it peaked between 16k and 20k (most likely user error , but in short it is inserting pins or nails into the sides and then attaching a metal wire to hang it. I'm VERY happy with the result and with a little bit of EQ I'm sure it may be even better.

[OB_Newbie]

Hey Odal,
Yeah, I got my replacement Ultra and that one quickly failed.  They are fragile with very thin leads that are attached to the plastic spider.  I have solderless disconnects and because of the small tabs they connectors can come off.  I blame myself... when I reconnected the exciter while the music was playing... the excursion caused the thin leads to break.  Despite that I still ordered 4 more because they really sound fantastic on XPS. 

Kinda got sidetracked with the birch panels so I have yet to use them.  This past weekend I returned to the XPS panels and have to admit that they sound better than the play panels.  The XPS is efficient and more detailed than the ply.  Granted, my ply is thin and needs the balsa bracing and I'm sure they they could be improved.  I really like they way they look but the sound of XPS is really hard to beat and I am just about ready to try the Ultra's again.

I'll report back again on the Ultra's.  Wondering it they will sound as good as I remember.  Hmmmm, dang... now you got me thinking... I'll have to get them up and playing tonight and see how they fair!!      

[Squibby]

Hey Odal3 and OB_Newbie,

In all fairness, when i did the measurements it was during the window of opportunity i had when my daughter and wife had left the house for 5 minutes and involved me hastily putting everything together and holding the iphone in my hand to take the measurements, which i realise is not ideal....it was quick and messy!

if i get another chance to do it i will make sur the iphone mic is held firmly in place or resting in the same position equidistant from the speaker and i will do a volume sweep beforehand.

apologies for the previous crappy measurements....just thought it may give you guys an inkling as to what is going on.

all the best,

Squibby.

[OB_Newbie]

Hey Squibby!
Sorry if we sounded negative... I was just happy to see any kind of measurements just to see what was going on fully framed and suspended.  Pretty darn smooth in the critical mid-range and bet they sound good indeed.  Thanks man!!
     
I know how that goes with the family.  I had a few hours without the fam the other night and got to listen to the Ultra's at more realistic levels.      All I can say is wow.  Even before the first exciter failed... with a breif listen... I could tell that they sounded better than the Thrusters.  The Ultra's really are opening up and are playing incredible music in my listening room... hard to believe but they are clearly level or 2 above the Thrusters in sound quality.  They are fragile, prone to failure and may not play quite as loud but I don't care... they sound fantastic. 

They are on sale right now too I see... all exciters at PartsExpress are so if anyone oversee's wants to try a pair or 2 I don't mind posting to you to save on shipping costs.  Feel free to PM me. 

       

[Odal3]

Squibby,
On the contrary, I was excited to see the measurements. Half of my measurements include small feet running around or an occasional dropped toy on floor in the room over where I have my "audio lab". Didn't mean to come accross as negative - just to give a helping hand so we can continue this together. Everytime I'm reading this forum I always learning something new and that's why I'm keep coming back. Please post more when you get around to it!!

OB_Newbie,
So officially only a 2 star rating for the Ultras (assume that was you) . Since the trusters are out of stock I'm thinking of getting 2. You may have alreday mentioned this, but I forget, do you think they will work on wood as well? Is it a higher frequency output or what is it that makes them sound better?

Haven't been to the PE site in a while. Is the DAEX30HESF-4 something else to consider? I had not seen that one before. Don't really understand specs for these exciter other than the W output.

Have anyone made a some experimenting to see how low the frequency goes on different panel sizes. I want to try some smaller panels for looks and I can fill in the low-end with subs.

[Squibby]

Hey Odal & OB,

no need to apologise at all.....i appreciate the education especially on topics i dont have much of a clue about such as audio fidelity and frequency measurements.

I'm going to order some of those ultras and perhaps a thruster or 2 to do a comparison and try them out on some xps....i need to know the difference between what you guys are hearing and what i'm content to listen to with my wooden panel!

I may even coat the xps with 1mm wood veneer....who knows....i have my reservations about not using wood and losing that richness of tone (plus the aesthetics are not too shabby and certainly beat looking at foam!)

thanks for the kind words and dont worry about hurting my feelings with constructive criticism...the knowledge i gain far outweighs any negative thoughts i could have (plus i'm a big boy....i can handle it.....sniff).

all the best,

Squibby.

[OB_Newbie]

Squibby,
On the contrary, I was excited to see the measurements. Half of my measurements include small feet running around or an occasional dropped toy on floor in the room over where I have my "audio lab". Didn't mean to come accross as negative - just to give a helping hand so we can continue this together. Everytime I'm reading this forum I always learning something new and that's why I'm keep coming back. Please post more when you get around to it!!

OB_Newbie,
So officially only a 2 star rating for the Ultras (assume that was you) . Since the trusters are out of stock I'm thinking of getting 2. You may have alreday mentioned this, but I forget, do you think they will work on wood as well? Is it a higher frequency output or what is it that makes them sound better?

Haven't been to the PE site in a while. Is the DAEX30HESF-4 something else to consider? I had not seen that one before. Don't really understand specs for these exciter other than the W output.

Have anyone made a some experimenting to see how low the frequency goes on different panel sizes. I want to try some smaller panels for looks and I can fill in the low-end with subs.

Hey Odal!
Hehe... yeah, that was me with the slammin' 2 star review.     They are fragile and the reason for the 2 star review.  Not sure if it will work well on wood or not, I think we will have to give it a try.  My assumption... and its only a assumption... the Ultra's have a low Fs and assume its more compliant and may not exert as much as much force on heavier materials.  Whereas the Thruster has a more rigid steel spider and can only imagine that it will exert more force on a ply panel.

Why does the Ultra sound better?  I think its high compliance/Mechanical Q that results in a low Fs as the motor is mounted via a soft rubber spider to the outer hard plastic case.  I could tell immediately the instant I listened to the Ultras.  I explained it as sounding "quieter"... like an improved Signal to Noise ratio.  They sound clearer and cleaner than the Thruster model.  The Thruster is very nice, great sounding, reliable and really a great quality exciter.  On XPS though, the Ultra's are very, very good sounding.  I didn't want to like them after 2 failed but they sound fantastic.  I"m ordering more to be sure I have enough around as a back-up.

I'm going to try the DAEX30HESF-4 exciters too... just to see how they sound.

Can't decide on size of the panels but wanted to build a panel array since the beginning.  I want to try a smaller panel just too to see how small I can go as I always assumed I'd build another pair of OB subs for bass duty.  Though recent EQing has me second guessing myself and wonder too if even 4 small panels can be as successfully EQed like the larger 24x30 panel.

I'll report back hopefully later this week.