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IOWA DIY 2022
Hello fellow DIY brethren. It's about that time again to start planning for the next IOWA DIY.
Let's start this thread with an informal discussion on where we would like to see this event take place.
Full disclosure: I really don't give a shit. The Best Western has been very accommodating and is as convenient as can be, but TBH, their listening space is far from exemplary.
In prior years, we've gathered at Grinnell College. I won't go into detail on their venues, but suffice it to say, they have several quality gathering spaces. 
What say you?
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I am OK with any location, just need time to plan the travel.
I'll go wherever somebody plans the event. I can't bitch if I'm not contributing to finding the location.
Gunna try to make it this year. Don't care where.
I vote for the hotel in Ankeny. The venue isn't horrible, and the amenities are great. The comfortable lobby adjacent, no guest rooms near the venue space, and plenty of restaurants in the neighborhood are all serious pluses versus, say, Grinnell.
I've always liked Harris auditorium in Grinnell for the acoustics and seating. Plus it seemed that smaller speakers didn't have to strain as much. But as others have stated Ankeny is fine too.
On a tangential subject (and probably deserving another thread): I would like to propose using band limited pink noise (REW uses 500 to 2000 Hz) instead of using full range. My rationale is as follows:
2.Using full range pink noise forces the smaller speakers to output their band limited frequencies at a higher level than bigger speakers to achieve the same over all SPL rating. This essentially requires them to play at louder levels where hearing is most sensitive.
Using band limited pink noise puts speakers in the same SPL range at frequencies that all speakers should be able to produce.
Bigger speakers will still sound deeper and more complete due to their lower octaves, but the smaller speakers won't have to "scream" in order to compensate for their missing bass SPL.
It will actually make it easier to compare big and small speakers since they will be level matched in the frequencies they have in common.
Anyway, I thought I'd throw out the idea.
I have never heard of band limited pink noise but it sounds like a perfectly acceptable option. While we are talking SPL, I want to add that I think we dialed it down too much last year.
I propose that we, as a group, decide what SPL level is good on Friday night during the informal. Band limited pink noise it is. Thanks Ed.
I'm good with either location. My anniversary is the 7th, so that's the only weekend I can't make work. I don't know if I'll actually be bringing anything this year, but I was planning on being there regardless.
Hey Alexis. It will be awesome to see you again. Will you be coming up from Texas?
I really like Ankeny for all the same reasons JR pointed out, as well as the really nice free breakfast. I feel the listening room is slightly better than the room at Indy and more or less the same as the Grand Rapids room.
I also would like to try Ed's idea for setting the level. Seems logical.
Slightly off topic, could we mix things up a bit this year and not do the smallest first and save all the big speakers for the end of the day? Being selfish I know but I'm most interested in hearing the bigger ones (3 way towers for example) but my ears and focus are a bit spent by 3:00 pm on Saturday.
I will be attending regardless of where it's located or the level matching scheme or the order in which projects play.
That is the idea.
Just thinking out loud here. The options are Grinnell, which has good acoustics, but is in an unpopulated area, the Best Western which has mediocre acoustics and is in a populated area, or another hotel in Des Moines. A populated area is a definite plus for restaurants and such. Is there another Grinnell type of facility in a populated area? In the end, I'm showing up regardless.
I don't know if a venue like Grinnell can be found outside of another university lecture hall or an IMAX theater. That room was designed and built specifically for its acoustics. But on the flipside, I highly doubt any of our listening rooms come close to sounding like that. Even still, that room was not perfect. I remember one year where we all threw our coats and jackets on the floor just in front of the stage to reduce the strong floor bounce (the stage is about 24" higher).
I was specifically commenting on the Harris Hall venue. One year we were in the "Harry Potter" room which was the worst room I've ever heard aside from a high school gym. I missed the next year at Grinnell but read the new room was very good.
I'll chime in and vote for Ankeny. My opinion is Ankeny has much better acoustics than Grinnell. I never cared for Grinnell. Bass was always exaggerated and boomy with no typical listening room reinforcement of the sound. Ankeny may not be perfect but I think it provides a better listening environment.
Jim
Either venue works for me.
Ron
I would likely not attend, but will say Doug toyed with that idea of limited band noise as has Dayton/MWAF.
My takeaway from those endeavors is that it mainly only serves the level aspect alone. You can't tell spectral balance from the band limited noise like you can pink stuff. AND i have seen failures from this method. It took one of my mids out in the Icthus back in 2008. The thought from the group was the center of the tone was at the lower cutoff of the mid, and overdrove the apparently flaky highpass cap. I replaced the caps and the one mid after the fact.
When using pink noise, it's standard is -20dB from reference, and while some speakers or attendees may have complained, I've not seen any failures resulting from this method. It's easy to tell spectral balance and warm the drivers from a cold state.
I feel the benefits outweigh the fairly minute risk.
My 2c,
InDIYana Event Website
Just to be clear - I was talking about using band limited pink noise just to set the level. REW has a pre-set "Speaker Cal" pink noise from 500 to 2000 Hz. I'm sure we'd use a lower overall SPL level than when using fullrange. From the REW help file:
The Pink Noise generator uses white noise filtered through a -10 dB/decade filter generated from a weighted sum of a series of first order filters, as devised by Paul Kellet circa 1999. Stated accuracy is within 0.05 dB above 9.2 Hz at 44.1 kHz sample rate.
The Full Range option outputs the filtered noise directly, giving the widest bandwidth and the greatest low frequency content. The Speaker Cal option applies 2nd order (40 dB/decade, 12 dB/octave) filters at 500 Hz and 2 kHz, producing a signal with its energy centred on 1 kHz. Sub Cal applies filters at 30 Hz and 80 Hz. Both are broadly in line with the THX test signal recommendations. CTA-2034 filtering applies shaping in accordance with ANSI/CEA-2034-A Standard Method of Measurement for In-Home Loudspeakers.
I would prefer Ankeny, but would show up wherever it's held.
I'm hoping to make it this year, depending on a few circumstances and if the planets align. Do you have a target date yet?
We've typically aimed for third week of October, so 10/21-10/22 will be the target weekend unless there is some reason to do it the previous weekend. I don't follow college football, so can any Iowa peeps weigh in on the best time to schedule? I'll get back in touch with the Ankeny BW on their conference room availability. Seems like we have a consensus on the venue, which is fine by me, and I agree, the BW room is more reflective (pun intended) of a typical listening room.
Is there a link to or free resource for the band limited pink noise? @Ed_Perkins do you have a sample to share?
Just set your SPL using A-weighting and use same test signal for all speakers...
THX test methods are for determination of peak SPL capabilities. Same for CTA-2034 filter, used for determining max SPL, nothing to do with level matching.
Oct. 15 sees the local team @Texas and Oct. 22 is a bye week, so either would be comparatively low volume weekends.
You can use the signal generator in REW (free) to create the pink noise file. Or I can create it and post it via dropbox. Just let me know how many seconds you want it.
If anyone is coming from or passing by Columbus Ohio I will pay a nice transport fee for a 30x24x24 carton that weighs 130#...
Transmission transport covered.
See you nerds this October!
Oh, and I expect to bring a coupla three little speakers using those AliExpress midbass drivers. One pair will have whichever AliExpress Vifa knockoff tweeters I determine is the best option, one will be using the small for factor SB ring radiator, and the third will be using the GRS Fountek knockoff. Particular combos will likely be determined after testing of each driver is complete. I've got exhaust and some tuning yet to do on the truck but I expect the majority will be done this weekend. Also, I have a retaining wall I need replaced else my truck slides off into the neighbors yard. I will likely need to drink Hamm's over the Iowa weekend due to low fundage.
I now return you to your regularly scheduled broadcast.
Hamm's is from the land of sky blue waters.... I once accepted a case of Grain Belt as payment for speaker design work.
Sehlin Sound Solutions
Thanks Ed. I'll take you up on a 20 second sample. Kindly set that up at your earliest convenience. I'd love to run it on my go-to office system and compare with the track I've been using for some time now. I know it sounds corny but I'll be watching the excursion on woofer. I've always thought that the pink noise track at the beginning of the many Iowa house tracks I've produced have effected more excursion than the actual demo track. This is my experience running the house track at various levels in my home office, AKA, where I produce the demos and being able to watch closely as the RS180's in my monitors look like they want to jump out of the boxes.
Try these dropbox links to band limited (500 Hz to 2 KHz) and full range pink noise versions:
https://dropbox.com/s/eaiwbnf4aiv4q7h/PinkNoise_20sec_500-2KHz_-9_dBFS_96k_Float_LR.wav?dl=0
https://dropbox.com/s/isxapxlca2tzobn/PinkNoise_20sec_FullRange_-9_dBFS_96k_Float_LR.wav?dl=0