Tech evaluation of the Iron Driver Loudspeakers

[r-carpenter]

Re: Tech evaluation of the Iron Driver Loudspeakers

I was wondering that exact thing after seeing the last two.

here you go

The difference is there and it's measurable, however it is small and considering that all speakers were played in the same environment and even at the same positions (stands were not moved), I don't see it as a potential issue which could tilt judges one way or another.

[ryanbouma]

Re: Tech evaluation of the Iron Driver Loudspeakers

Agreed. And didn't mean to imply it would throw off results. Thanks for doing that.

[r-carpenter]

Re: Tech evaluation of the Iron Driver Loudspeakers

Agreed. And didn't mean to imply it would throw off results. Thanks for doing that.

I wanted to decapitate that dragon immediately because it would invite an endless argument. Ideally we should have blindfolds or dark shades to eliminate the influence of the screen. The point was valid and may be for the next competition, shades would be an option.

[mzisserson]

Re: Tech evaluation of the Iron Driver Loudspeakers

I wanted to decapitate that dragon immediately because it would invite an endless argument. Ideally we should have blindfolds or dark shades to eliminate the influence of the screen. The point was valid and may be for the next competition, shades would be an option.

They all suffered the same. I am glad the measurement with and without is negligible. Thought it woudl be. I did not hear it when we put it over... I DID hear 2 layers though, glad we found the wrinkle technique for hiding them.

[DE Focht]

Re: Tech evaluation of the Iron Driver Loudspeakers

David Crewe.
(missing vertical off axis and may redo it tomorrow)

Best Phase ...best sounding speaker, smart move on the tweeter level for a contest, obviously someone learned some lessons from Stereophile measurements.

Drop the tweeter 2db for long term listening and you get fuller sounding bass back too! For head to head Vivid beats Bass, which is why the other "vivid" speaker (Foster-Bouma) was selected as a best sounding speaker. Lesson learned for next Iron driver!

Very Smart design by DC. On paper the clear winner imho.

Great contest Mike and Roman!!! Great results.

[mzisserson]

Re: Tech evaluation of the Iron Driver Loudspeakers

Best Phase ...best sounding speaker, smart move on the tweeter level for a contest, obviously someone learned some lessons from Stereophile measurements.

Drop the tweeter 2db for long term listening and you get fuller sounding bass back too! For head to head Vivid beats Bass, which is why the other "vivid" speaker (Foster-Bouma) was selected as a best sounding speaker. Lesson learned for next Iron driver!

Very Smart design by DC. On paper the clear winner imho.

Great contest Mike and Roman!!! Great results.

It worked out well. It also showed that the flattest FR response on axis does not always yield a winning result. It is a combination of MANY factors. I agree with your statements. Though there was not a brightness to his, or Ryan's speakers so please do not misinterpret what you see. They were very well balanced. It would be interesting to see as you get them closer to a boundary what happens, but in the case of both of them you would just Gain the reinforcement and any vividness they may have had would balance out.

[ryanbouma]

Re: Tech evaluation of the Iron Driver Loudspeakers

If the on-axis measurements of any of these speakers seem to show some kind of "vividness", I'll repeat what I said before. I have quite a bit of experience with the iron driver (which likely helped with our score) and it naturally has a full sound, regardless of the amount of BSC used. Whether it's from lot of 2nd order HD in the bass, or what, I don't know. I haven't bothered to look into it that much.

I compared these two speakers (not the 3rd one down) side by side in my room: http://www.diysoundgroup.com/forum/index.php?topic=37.0

One uses the 830656, the other uses the Dayton DS-175. Night and day difference. The 830656 has a thick full sound while the DS-175 has a clear sound. And it's very obvious. So a slight rising response is exactly what this driver is good for, imo.

[ryanbouma]

Re: Tech evaluation of the Iron Driver Loudspeakers

FYI, here is my personal measurement of my build of this speaker (we each built our own):



Smeared below about 400hz as I did these in my room with a fairly short 3.5ms gate iirc. So you don't really get to see the baffle losses like Roman's measurements do. Hmm, maybe I should haul it outside and give these some torture testing...

Matt's version recessed the woofers while mine did not. (miscommunication ;) )

[mzisserson]

Re: Tech evaluation of the Iron Driver Loudspeakers

If the on-axis measurements of any of these speakers seem to show some kind of "vividness", I'll repeat what I said before. I have quite a bit of experience with the iron driver (which likely helped with our score) and it naturally has a full sound, regardless of the amount of BSC used. Whether it's from lot of 2nd order HD in the bass, or what, I don't know. I haven't bothered to look into it that much.

I compared these two speakers (not the 3rd one down) side by side in my room: http://www.diysoundgroup.com/forum/index.php?topic=37.0

One uses the 830656, the other uses the Dayton DS-175. Night and day difference. The 830656 has a thick full sound while the DS-175 has a clear sound. And it's very obvious. So a slight rising response is exactly what this driver is good for, imo.

I think you hit it head on, too Ryan. I have damn near the exact results with the 175. Very low distortion but 3rd dominate. It is not all warm and "magical", but very clear and what many would define as "accurate". It starts becomeing less about "BSC", flat FR, Polars, and all of these things we know needs to be in check, and more about understanding the audible charasics of the drivers you are working with. For me, thi adds more confirmation that measurements are not an absoulte, rather a highly specialized toolkit. It is really about the designer understanding the drivers they use and their capabilites beyond what is on paper. Can it be explained, sure it can, but can you learn over time that A characteristic meand B result when used in C application? Yes, and you become less reliant on haveing to sweat datasheets to make good drive choices/parings knowing by a small amount of data that a given driver will exhibit certin characterists. And so begins the arguement of what seperates a good designer from just an engineer.

[scottq]

Re: Tech evaluation of the Iron Driver Loudspeakers

Best Phase ...best sounding speaker...

Easy now... the phase on my design seems to be one of the best, and it got last place. Granted, the FR looks like a view of the Denver horizon at sunset... :eek:

Dave's FR (as pointed out) was far from the flattest, but it is pretty darn good across the primary/fundamentals region, where our ears are much more sensitive to change and detecting abnormalities. IMO, I feel the winner was made by a combination of three aspects (phase, "flat" FR within the fundamental mid/vocal region, and Dave's well thought out plan to separate the mid/woofer chambers).

The rising high end helps not only with the dB or two drop (as verified by Roman's measurement) but also with the wide range of off-axis, non-ideal seating at a DIY event.

I think the biggest weakness in my entry is the notch around 300Hz. I had originally measured with no stuffing in the mid chamber. There were some pretty wild standing wave resonances in there that got tamed with the poly during listening tests. And those were filling in that big hole during measurement. The standing waves gave a very nasal-isch sound to things. If I had more time I would have certainly remeasured and redesigned the XO to fill that void more, at least as good as could be done within the budget.

Mike/Roman: Out of curiosity (sorry if I missed it posted elsewhere), was there any toe-in put on the speakers? Or were they played straight out into the room? And what was the spacing? 10ft?

[monoiz15]

Re: Tech evaluation of the Iron Driver Loudspeakers

Ron E got my best vote for sound, and they look beautiful, good job!

I always make my speakers accessible for servicing, I could brace it more if I wanted. I think I'll just keep it in mind for future projects.

I seem to remember grading ours high on treble quality, but low on mid/bass balance because in the room it seemed to have less than most of the designs. In my bedroom the bass is huge and I actually don't think a sub would really help at all other than extending the bass a tad lower at the expense of trying to integrate it properly. Simply not worth it to be honest, I have many other projects to get to work on. I MIGHT try and pad down the tweeter just another dB or two though. At high volumes, it's just too much for some music.

I'm bringing them into work today to play some stuff, its been pretty slow and I wanna show my boss. Its just me and him that work there makin' tacos. mmmm

Thanks for the data, Roman!

[mzisserson]

Re: Tech evaluation of the Iron Driver Loudspeakers

Ron E got my best vote for sound, and they look beautiful, good job!

I always make my speakers accessible for servicing, I could brace it more if I wanted. I think I'll just keep it in mind for future projects.

I seem to remember grading ours high on treble quality, but low on mid/bass balance because in the room it seemed to have less than most of the designs. In my bedroom the bass is huge and I actually don't think a sub would really help at all other than extending the bass a tad lower at the expense of trying to integrate it properly. Simply not worth it to be honest, I have many other projects to get to work on. I MIGHT try and pad down the tweeter just another dB or two though. At high volumes, it's just too much for some music.

I'm bringing them into work today to play some stuff, its been pretty slow and I wanna show my boss. Its just me and him that work there makin' tacos. mmmm

Thanks for the data, Roman!

Don't be so quick to blame the speaker for increased treble at high volumes. (unless you are using you Inuke amp) As amps run out of steam and begin to clip, I find they can get harsh, quick. Even if you are using your inuke, if you start getting to the 100WRMS territory, you may have raised the THD of the amp enough to be audible. We were in a big room playing at fairly agressive 1m levels, it would have come out if there was an issue at volume.

[r-carpenter]

Re: Tech evaluation of the Iron Driver Loudspeakers

Scott, you have impedance phase, acoustic phase of each driver and acoustic phase (minimum or relative) of a complete loudspeaker. Smooth impedance phase, just means that an amplifier will have an easier time driving it. Of cause efficiency or sensitivity and impedance make a big difference for an amplifier load as well.
We had speakers about 9ft apart and set them with a slight toe in.

There's something that concerns me in this discussion and I'd like to address it somehow for the next Iron Driver.
It looks like the designs targeted for "vivid" sound as Mr.Focht described it, tend to score higher in the short term listening tests. I would certainly hope that this will not turn in to a tweeter level and mid-range level wars with total disregard for BSC. After all, the objective of this shootout is not only to take the first place but also have a speaker, worth reproducing. This statement is not at all a critique towards winning speakers. David Crew for example send us a concept which he used to create his design. I completely agree with his line of thoughts and perhaps he could share it with the rest of the members. I myself justified raised response of the tweeter by the preferred seating at live events. So, it is something to think about and probably try to even out or neutralize, so this competition does not become a 15min wining race.

[ryanbouma]

Re: Tech evaluation of the Iron Driver Loudspeakers

Are we talking about impedance phase?? That's of so little consequence it's hardly worth mentioning imo.

The point about the top end being lifted to span a wide audience is a good one.

[r-carpenter]

Re: Tech evaluation of the Iron Driver Loudspeakers

The point about the top end being lifted to span a wide audience is a good one.

We noticed the scoring issue on the previous DIY event with a beaming full range drivers. Only two guys in the center are getting the high frequency and the rest of participants are scoring top end low. Not much of a new thing.
Raised top end response with smooth off axis may be the reverse issue. Two guys in the center will find it bright but the rest of the people that are seating off-axis will prefer the tweeter level. Unfortunately, this arrangement and levels may not work out so well in the final listening environment.