Iowa DIY 2026 - ElectRelics

[technodanvan]

This project is kind of a rush since I’m trying to get it done by IowaDIY in the middle of October. I’m waist deep in parts and it’s a struggle to move forward on everything but I spent some significant time working this out. On a phone right now so details are slim, but here goes. This will hopefully be a largish bookshelf that pushes my 3D printers to their capacity.

Tweeter: Peerless DA25TX

Midrange: TBD - FaitalPRO 5FE125, Anarchy 558, MAC-05, and Satori MW13TX are all contenders. Not sure I’ll have time or filament to make test baffles for all, but I’m definitely going to test the FaitalPRO and the Satori.

Woofer (rear firing, separate chamber): Anarchy 708 with a Dayton Audio RSS210-PR in a downfiring situation.

Lots of questions, very little time to get things done. CAD work and progress photos below. Essentially I’m making two trapezoidal enclosures. One shallow enclosure around 4-5 liters for the tweeter and mid. One ~10 liter enclosure for the woofer, PR, and hopefully the crossover.

[JonMarsh]

Interesting progress, but I know from experience that getting things done on a tight schedule is never easy...

[technodanvan]

Indeed, this will be pretty tight, especially if some of the crossover parts are difficult to source. Here's hoping I have most of what will eventually be needed.

The color of the Satori matches really well with the baffle, IMO. It's less black than the 5FE125 and is close to the shade of gray selected. Baffle for that one is printing now.

[technodanvan]

Rear baffle is pretty good, minor improvements need to be made but this will work for testing I think. Printing the woofer cabinet now. It's a 3-day print on that one so hopefully I got it right the first time (and hopefully the print doesn't fail!).

Edit: Not sure what color of bolts to use (black or silver stainless steel). I was planning on black for the 9 bolts that hold the baffle on and mirroring that for the little guys, but I think black would look weird against the red input plate.



Edit:

Satori baffle and surround are complete as well. Big fan of the appearance.

[technodanvan]

The 3-day print that was the woofer cabinet sides turned out okay. Something is going on with my seals, for some reason they only fit one direction and I'm not sure if it's the seal or the cabinet. Seal is easy enough to modify but it shouldn't need to be. Very confusing. Anyway, the cabinet itself needs to be updated a bit so I may have two more very long prints to endure. I'll probably still use this for testing though as I need to get moving on that.

This is not going to be a small speaker. However, with the PR resting there and nothing bolted together, the cabinet feels quite light compared to what I imagine a Baltic birch version of the same would weigh, so that's nice.

[Steve Manning]

Looking very cool Danny

[technodanvan]

I've started measuring a bit to get my head wrapped around what I have here. Turns out the 5" bolts I ordered to hold the front baffle, mid chamber, and woofer compartment together were about an inch too short for the job, but they were sufficient for the front baffle and mid chamber so I started there. The 6" bolts will be here before next weekend, so I probably can't test the woofer until then. My first test failed miserably and I was confused until I tried a second and third tweeter. Turns out that very last unpaired tweeter I got from PE a couple years ago was DOA, so that's kind of a bummer. Of course now I have a dead one to tear apart and (perhaps) think about waveguide development for the others.

But that is a future project.

Initial Satori and Peerless combination is shown below. Keep in mind this is a rudimentary setup in a pretty small room - I'm basically just proving my setup is working - and no gating has been applied here either. Clearly a room issue at ~400 Hz, I'm guessing it's the distance to the concrete floor (which I have no rug or anything placed upon. Probable room issue between 200-300 Hz as well, that would correlate roughly to the distance to the nearest wall. Input voltage was static (but not set specifically at 2.83v), but shows we won't need to attenuate the tweeter much to get it in line with the mid.

I'm trying to determine how I could maybe get this setup outside.



After this, I got to thinking about how to measure the woofer since it is rear firing. My first thought is to leave the test setup the way it is - about a meter or so away from the speaker, and have the front baffle pointed at the mic. This would emulate how the speaker would actually be listened to, which seems appropriate?

Now, I'm sure the combination of REW and VituixCAD would allow me to measure the woofer directly (woofer pointed at the mic) but I don't know how to do that being the novice that I am.

Thoughts JonMarsh?

[JonMarsh]

Hey Danny, looks like you're making some good progress with the cabinet fabrication!

Now, about measurements, or what I typically do- for example, I have a concept project on hold derived from the Diapson, originally a candidate for the Satori MW19TX, but then I must have accidentally sniffed some glue or had a glass of wine, and got it in my head that perhaps the PuriFi PTT8.0NAB (which I have some of still) would be an even more powerful candidate as regards output and distortion, and might handle the frequency response needs adequately combined with a DA32TX and it's extended low end.

Now, I'm a Fuzzmeasure from RHØDE Test boy for a variety of reasons, including all the cool acoustics measurements it can do that are not just about speaker design, and from the way it approaches setup and control. To each his own... it has an awful lot of flexible control and functionality baked in, and taking good advantage of Apple API's, so yeah, this is only available on a Mac.

So, when I get started, after deciding on an enclosure design and specific driver, the next step for me is generating what I call a QNF, "Quasi Near Field" measurement, which doesn't quite follow the classical description; I usually use measurement at a distance of about the diameter of the driver radiating cone, something around 4-5" and keep that fixed distance for things like dome midranges and tweeters- the intent to be close enough so that baffle step response and room effects are greatly attenuated. The intent is to get a good idea of the driver response with the rear volume of the design, and as close to large flat baffle free field, by making the direct sound far stronger than any reflection or outside cabinet effects.

I have a range of preferred impulse width measurement conversions from the sine chirp, and a preferred sine chirp duration. For nominal full range measurements, thats 100 msec; and that's what I usually use for QNF. On top of that one has time offset controls, amplitude sampling filtering (from 1/48th octave down to 1/3 octave) and a variety of impulse filter functions on the step response, like rectangular, Hamming, Half Hamming, Hanning, Half Hanning, Bingham, etc. You get the idea.

And I usually do non near field measurements at several distances, like 0.5 to 0.7 m, 1m, 2 m, so that I can see tradeoffs in the cabinet and driver response versus the specific test or listening room and it's interactions. I also like Fuzzmeasure because of the flexibility in combining primary SPL and distortion harmonics. Mainly I focus on 2nd and 3rd, to get an idea of the balance of odd (level sensitive) and even (polarity sensitive) performance. (there are a lot of drivers in the past that have much higher 2nd order distortion than 3rd, and this contributes to more IM and congestion when playing music- ScanSpeak, I'm looking at you... )

Note, while Fuzzmeasure can generate absolute acoustic level plots inputting calibration data, the basic response plot is based in dB around the response of the A/D system in the hardware one is using, and so is a guide to setup and avoiding test distortion from the gear- I usually shoot to keep maximum levels no higher than -10 db. And most tests are done with 2.83 VRMS at all times, monitored on a digital oscilloscope connected to the DUT terminals.

So, for the PTT8.0 in an old Madisound cabinet, sitting on a tall stool on my test angle turntable, at 0.7 meters, this is the result:



This shows baffle effects and to a lesser extent room issues.


Here is the QNF measurement, no change to the setup except for the microphone position and reducing the mic gain:





These are with a newer microphone than I've been using in the past for a long time; it's an Audix TM1, which seems to have a lower noise floor and returns better results on distortion tests on high performance drivers like the PuriFi parts. My other microphone is an Earthworks M30. The test controller preamp is a MOTU M4. The system preamp is a 2nd generation Schitt Freya with the Nexus balanced current mode amplification; the current version of that is called a Kara, as Freyas now all have solid state plus vacuum tubes.

Note, considering the sensitivity of the PuriFi PTT8.0, the output distortion for a speaker is VERY low...

[JonMarsh]

A little more info- this is what one of my test carts looks like, the one with the Schitt preamp and Cambridge Audio Azur 840W stereo power amp, which itself is very clean, and has a low noise floor. However, it currently has a Mac Studio desktop computer and LG monitor, instead of the 10 year old laptop.