Another 604 MLTL build (ping GM)

[omodo]

Thanks for looking over the sheets. I must have missed the BL parameter, and Sd was pulled directly from the GPA datasheet. I have also been modeling a BR using WinISD and cross checking the values BL was 19.5 in WinISD, so I completely missed that inconsistency.

With the corrected BL and Sd values, using 0.20 lb/ft^3 stuffing and adding 3r5 series resistance the sim looks much better, this gives me a lot more confidence as prior to this the response looked a bit ordinary

Zdriver 500mm - updated

thanks also for the placement advice, will take it into consideration when I start on the in-room modeling, agree the windows will pose a bit of an issue and are my main concern, at the moment they are covered with timber venetians and relatively heavy drapes, but probably not quite as heavy as 'thick comforters', so short of ripping them out and bricking in the cavities I'll have to make do with what I have

You're welcome!

I typically use the 1" acoustic fiberglass insulation (now OC 703?) seen in virtually all Altec cabs after Celotex was discontinued and best I can tell, lining one of each parallel wall = ~0.2 lbs/ft^3 in MJK's software, but many folks have gotten back to me that in my cab designs it tends to be too much, so recently I've been suggesting lining just the top and hanging a full height insulation 'blanket' of polyfil or similar diagonally across the cab and shortening it if need be. Several folks said they wound up shortening them all the way back to just below the driver, which makes for a pretty lively looking sim, so Caveat Emptor. If I get a chance, I'll have to try it in my cabs.

One more time:

"FWIW, based on MJK's math, driver ideally needs to be down from top ~14.83" i.d. and mine puts it at ~19.63" and offset horizontally in a golden or acoustic ratio which JF chose not to do. Never having compared the two, don't know if what differences one sees in a sim is audible and/or whether one sounds better overall. You can view the changes in MathCad and how stuffing density affects it."

Right, wrongly or somewhere in-between, I arrived at a way to calculate the technically 'best' driver location as I understand the physics of the situation ~36 yrs before I could sim it and ~15 yrs before I could measure it with a 1/3 octave RTA, which needed to be 1/6 to ~ match what I was hearing, but one makes do with what one can afford. You want more info on how different locations affect in-room response, then knock yourself out doing the necessary 'due diligence' and please share your findings.

WRT your sims, they're unfortunately completely bogus since BL is off by almost a factor of two. Even if BL is published, one should always calculate it when using published specs and why MJK has a BL calculator WS. Unfortunately it would still be off due to the Sd you used being too large for any 604 with 96"^2/619.354 cm^2 being more technically correct, though at a glance it doesn't change the MC sim, so assume it's a moot point.

Regardless, using HornResp or WinISD Pro to 'correct' published specs for inputting in various programs that require more than just Vas, Fs, Qts is a good plan plus it allows more accurate comparisons between the various simming programs.

GM

[atilsley]

I assume you've seen this project? It also uses floor vent.

http://www.6moons.com/audioreviews/altec/dream.html

I also like this Youtube clip on the Kult 604

The Jean Hiraga does it for me.....

[GM]

Thanks for looking over the sheets. I must have missed the BL parameter, and Sd was pulled directly from the GPA datasheet. I have also been modeling a BR using WinISD and cross checking the values BL was 19.5 in WinISD, so I completely missed that inconsistency.

It's still bogus, you used the BL for the erroneous larger Sd, so BL needs to be recalculated using the smaller Sd which will change the response considerably.

GM