Project preview - Budget 3 way

[brianpowers27]

Project preview: Budget3

Summary: A nice mid-low budget three way capable of playing cleanly around 100db. The drivers were chosen for their high dispersion characteristics and the woofer was selected for the quality of the clean bass it produces.

Drivers.

• Dayton RS225s-8 8" woofer
• Tangband w3-1053sc
• Dayton nd20fb 3/4" tweeter

Box specs:
wall thick'
0.75
inner outer
x 40.5 42
y 8 9.5
z 10.5 12
gross 3402 in2
misc 200 xo, bracing, drivers
net 3202
Ft 3 1.85300925925926
liters 52.4586921296296


Port
2"
7.5" 23hz

Note: mid chamber should be configured for 3 l. This is approximately 8.5,4,6
Bracing: 2 window pane braces. one just below the woofer, one directly above it.

Driver centers
tweet 37.6875
mid 33.34375
woofer 26.375


XO

• Active -- tested target slopes of [email protected] 450hz woof-mid 3500hz bw3 mid-tweet
• Passive coming soon based on targets in active simulation.

Impressions[list][*]Excellently clean for the money[*]Plays loud[*]Small enough tower to earn WAF[*]Dispersion is wide... could be good or bad depending on your philosophy[*]Resolves the intricate de3tails of John Williams' Star Wars theme and is meaty enough to belt out Nightwish.

[Guest]

Re: Project preview - Budget 3 way

Brian, if I build the cabinet volume at 52.4586965 liters instead, will it still sound ok?

[brianpowers27]

Re: Project preview - Budget 3 way

Brian, if I build the cabinet volume at 52.4586965 liters instead, will it still sound ok?

Let's DBT that with the listeners preferred music. The test will conclude after 3 nulls.

[Guest]

Re: Project preview - Budget 3 way

Let's DBT that with the listeners preferred music. The test will conclude after 3 nulls.

That would be laudable, letting the listeners use their own preferred music, but what should really be done is pick source material that has the highest probability of being audibly impacted by the internal volume change. The test condition should be as heavily biased as possible towards that perception.
But of course if its done in a "poor" room, detectability thresholds will elevate.
3 nulls is just plain wrong. Its statistically invalid. We should test the same condition many more times to arrive at any statistical significance. This should be done in a manner that resulted in no fatigue. Just like when we listen for hours and still hear jitter plain as day.

Having been involved as a subject or administrator of numerous double blind tests, I recognize a testing methodology designed to produce null or negative results in this test (Don't dare ask me for proof of this. I don't have to prove anything to anyone).

Critical audio testing should be conducted in a manner consistent to source material and application specific setting. Testing for music applications should be conducted in the "proper" venue. Home stereo type testing should be done in a setting optimized for performance with imaging and room interaction optimized in such a way as to eliminate "bad" setup and "poor" room acoustics removed as a variable set. SQ is the target, not test induced problems. This is why judging at DIY events is an unscientific, at best, leading to inconsistent results. Driving a pair of speakers with a low cost 100WPC switch mode power supply semipro amp in a barn of a room is not a "fair" situation when that speaker was designed and voiced on a low powered tube amp (scientifically proven in clinical tests to be more "revealing", "resolving" and "accurate") in a "good", but small room.
A persons cat in the room with the participant and the source is assinine and bad testing methodology as well as poor science. The cat could detect subtle changes in the participant and give subliminal cues for choices a la clever Hans.

Using familiar source material is essential to statistical accuracy. A baseline is necessary for every test and musical familiarty is THE baseline.

If the test is for enclosure volume and other sound related issues, the program material MUST be sparse enough not to mask the subject. Dynamic range testing would require a different program material set.

Stopping the participants' testing after 3 nulls is poor science in any statistical equation. Just flat wrong. Testing must proceed to the limit of attempts set by the administrator. Duh.
The source material MUST be returned to the same starting location for every change of test input. Crossfading is a bogus method of obtaining ONLY nulls and bad guesses. It does not allow the subject to do consistent cue comparisons needed for proper identification of the problem/solution. This is of upmost importance when the test is for SQ identification. Not only bad science, but it introduces the switching component as an unknown variable into the test. Again, duh. One thing that many test designers and administrators seldom consider is the brain makes more consistent decisions with a very short interruption in sensory input.

A related observation. It just cracks me up when I see "listening tests" concerning......uhm... capacitors conducted with equipment that perhaps contains a dozen 2 cent electrolytics in the signal path. To correctly conduct such a test the testing jig should have a minimal number of "very HQ" capacitors in the signal path (low DF, DA, ESR), similar to the ones used during the recording/mastering of every CD in dbe's and every other audiophiles collection, which will then be used for listening.

However, will our test be definitive? No way. First are all the test condition short-cuts I mentioned. Second is that this was purely a forced choice test. Be helpful if fatigue/long term exposure testing was also measured.
And lets not forget what we completely (unintentional or not) ignore, Such as sun spot activity that day. What color are the remotes used to pick? Are they pewter? This color is know to cause deafness and skew tests. Etc, etc, etc.
No matter what the test method, there will be 1000 excuses why it is invalid.
Unless of course, the result is as desired. Then we won't care.

cheers,

AJ

[brianpowers27]

Re: Project preview - Budget 3 way

AJ,

Don't forget to cite your references int he post above. Admit it, we are all audio nerds.

[Guest]

Re: Project preview - Budget 3 way

I prefer "geeks" myself.
Have you listened to this 3 way via the DCX already?
And whats with the dual tweeter centers? Rear tweeter?

[brianpowers27]

Re: Project preview - Budget 3 way

I did the simulations with in baffle measurements via PCD. Once I found an overall plan, I translated the targets into DCX2496 language. I measured for target responses individually via Arta.

It sounds great for what it is. The fact that all fo the drivers have great dispersion lends itself to a smooth power response. Directivity control isn't a real design factor here.