Coming back to life! Question about 10" woofer position in a 3 way speaker

[TacoD]

Great project, even 2.82 is already hard to achieve. You need a lot of components to make it happen .

[lunchmoney]

Wow. Those are some big fricking cabinets. Beautiful. And big. Really big. Those are big. Big.

Hey fjhuerta, do you think it would be possible to do these with only 1 10" woofer per speaker instead of 2?

Of course the crossover would have to change a bit, and the cabinet would get smaller (thankfully )...

I've got a pair of RS270's collecting dust, and I'm pondering what to do with them.

[fjhuerta]

Yes, they definitely could be built with one woofer. Sensitivity would drop to 85 dB/W or so. Somehow, I'd still use MTM W4's., I just think the lowered distortion would work correctly.

Yeah Taco, 2.82 was somewhat hard to achieve. I was expecting 2nd order electrical filters. I should have known better. Thanks!

[fjhuerta]

Still waiting for the crossover parts. They are getting closer. Meanwhile... new grilles!

Grilles off: no holes or markings anywhere.



Grilles on: still no holes or markings... love them!

[Paul W]

Beautiful work on both the XO and cabinets.

[TacoD]

Nice work, also show us how your assembled x-over when the parts are in. Do you have plans to put it on a single board or are you splitting it in smaller sections?

[fjhuerta]

Thank you Paul!

Taco, I began building the x-overs yesterday. I'm using a single board of MDF. It's bigger than needed, because I'm simply terrible at building crossovers. Most of the time when I look at all of your work I wonder how on earth can you be so tidy!

[fjhuerta]

It's ugly, but electrically and structurally (lots of crimping and gobs of hot glue) so far, it's OK.

[joeybutts]

Beautiful cab's Javier. If I didn't want to go for dark tones on my cab's I would consider this style.

Any plans for those feet, or are they finished? I can't tell by the pics....

[fjhuerta]

Oh no, those are temporary feet. I'll be using a pair of old style (the ones with the plastic base) spikes from PE, or a set of DSS-3's. I'm still not sure; I like the way the old style looks, but I'm not sure they'll be able to handle the weight.

There's also a strange thing going on in my family's life. Due to unforeseen circumstances, I think I'll be moving from my home in two weeks. It's definitely not a bad thing, it'll be a trade up. But we weren't expecting the move at all. The thing is, I'd definitely not want to add the spikes until the speakers are at their final place - they are just too heavy to move around, and I'm sure I'll seriously damage any floor the spikes come in contact with (interestingly enough, neither our new home nor our old one has any carpet floor at all).

[fjhuerta]

Done!



Considering how hard it was to stick the crossover inside the cabinet, I'm not planning on doing any more work for a while. It was hard... the crossover board was bigger than I expected and it *barely* fit inside. Wiring all the drivers was a nightmare. But it's done.

I have a 0.2~0.3 Ohm difference between tweeters, from 5 KHz - 20 KHz. I have modeled all options, and either the padding R is out of spec (highly doubtful) or the tweeters have variances among them. I think it's the latter.

I still need to do a pink sweep on them to check polarity. But from my 3 minute listening test there are no issues.

3 minutes is barely enough, IMHO, to know what I have here. But here are the things that suprised me.

1. Big speakers do sound different. They sound... well... big. I don't know how to explain it, but they sound completely different than my small monitors.

2. Once you get to a certain point, all speakers sound very, very similar. Nothing jumps out of the picture, except for the terrific bass. They *kill* my old ZDT3.5's, the bass is unbelievable - deep and powerful. My monitors, even with a 15" sub, can't compare at all. They sound.. "fuller", for the lack of a better word, and far better integrated.

3. The midrange is silky smooth. I love those Tang Bands!

I need to do the RTA sweep just as a sanity check, and live with the fact that I won't be able to listen to them for a while, since we are moving out of the house defintely in two weeks.

[TacoD]

Wow, good work. Your x-over boards turned out very nice. Do you have enough space in your next home for these babies?

[fjhuerta]

Thanks!

Yes. My current home has very high ceilings and open spaces. The new one doesn't have high ceilings, but the living room is bigger than my current one, so it'll work perfectly. They'll actually look great in their surroundings (a completely coincidental thing).

One thing I also noticed is how little the woofers move when listening at my usual levels. I can't wait to give them some power (I'll be using Channel Islands Class D monoblocks - supposedly rated at 380Wpc at 4 Ohm)!

[fjhuerta]

So, here's what I learned from this project. I'd say it was one of the most insightful experiences I've had regarding speaker building.

1) A room will break havoc on even the best speaker.
The room I'm using them is a festival of bad materials for speaker listening. Stone walls, part of the flooring is stone (don't ask, it's not a cave, though!), wood floors, and huge windows all conspire to make for a very uninviting listening experience.

I particularly had severe issues in the 3 KHz & 6 KHz range. An extra +3 dB hump on both. Nasty!

2) 3 way speakers with carefully designed crossovers suffer less from power response issues
Which is not as good as I think it should be. Off-axis there's a far better (flatter) power response from a 3 way than from a 2 way with big woofers (say, the Nat-P). But then again, room issues usually make this point moot. Once again, that damn room.

3) Big speakers sound... welll.. different.
No doubt about it. These speakers sound completely different than any other I've ever built - even my OB with a single 8", which sounded... well, huge (soundstaging, I suppose, due to the OB mids). My wife never notices how loud the speakers are - only when she tries to have a conversation she notices the volume level. This never happened to her - she always wanted me to turn the volume down! Not anymore. I suppose less distortion and far better bass are to blame (?) here.

4) Flat in room response is not always desirable
I said it before on some other thread. The speakers sound fantastic when used with well recorded material (say, Classic Records DVD-A's, or plenty of SACDs I have around), but they are pretty thin and harsh with badly recorded stuff (say, most of the CD's I actually... well, listen to!).

I used the preferred in room response curve from the Harman study (the one where there's a downward slope, +12 - 0 dB from 20 to 20 KHz) using the Inguz EQ on my Squeezebox. BLAM. Night and day difference. Suddenly, everything is so listenable it's amazing.

Unfortunately, I just can't seem to see a way to "dial in" this curve without a) designing as flat as a speaker as you can, b) positioning the speakers so as to smooth bass response as much as possible, and c) using a 31 band EQ to smooth the bass response even further, and dialing in the room response as necessary.

The results, though, are worth it. I love my system far more than I ever remember any speaker I built. Which makes me think whether some manufacturers actually "color" the speaker response so that the in room response resembles a downward slope.

Which may be a futile effort, since every room is different.

TL; DR - is a very high quality EQ the finishing touch for every DIY speaker system? I'm starting to think so. I may get a MiniDSP with the EQ module to play around when I'm not listening to the Squeezebox.

[dlr]

Which may be a futile effort, since every room is different.

TL; DR - is a very high quality EQ the finishing touch for every DIY speaker system? I'm starting to think so. I may get a MiniDSP with the EQ module to play around when I'm not listening to the Squeezebox.

First, let me suggest that you follow this thread over at PE. John K is doing some testing with the MiniDSP and is working on an issue that arose. It may not have an impact on you, but it's worth checking it out.

IMO, the crossover is make-or-break. It's far more important than many realize. I've settled in on the crossover for my new quasi-dipole as I call it now. The midrange and tweeter were actually easy, but this after having spent a lot of time in the preliminary stage of driver selection and baffle configuration. The integration with the woofer and some mods I made to the dipole configuration (now something of a hybrid between dipole and cardioid) took a long time, but were worth the effort.

It's also generally the case that the cheaper the drivers, the harder it is to design a good crossover. IMO.

Dave

[fjhuerta]

Oh, IMHO, the x-over is the heart of the system - get it wrong an no amount of EQ will help you. Ever. I've learned this the hard way - pick an erroneous frequency, use an uncalibrated mic, get the phase tracking wrong, and there's simply no band aid that'll help you.

I was thinking more about "dialing-in" the speaker to a particular room, while using the crossover to get rid of any nasties in the FR, keeping the drivers in their linear region, and padding them to a flat response. Then, after you've made all that is humanly possible, apply EQ to try and remove the room from the equation (impossible, I know, but it's better than nothing).

I think I'm enjoying more the part about how we perceive the sounds around us than building a perfect speaker. It's becoming obvious to me how a good design is only a start in the quest for great music reproduction - there's so much more out there.

[dlr]

I was thinking more about "dialing-in" the speaker to a particular room, while using the crossover to get rid of any nasties in the FR, keeping the drivers in their linear region, and padding them to a flat response. Then, after you've made all that is humanly possible, apply EQ to try and remove the room from the equation (impossible, I know, but it's better than nothing).

This is the never-ending quest it seems. I'm following a thread over at diyAudio that has as many opinions on this aspect as there are participants.

Dave

[fjhuerta]

Can you please share the link? It seems like an interesting discussion.

I did the "sanity check" on my speakers today (actually measuring them!) and was surprised to see I had an extra 4dB of low - high treble. Yikes.

So I decided to take it easy before taking everything apart, and started reading. Zaph comes to the rescue...

From the ZDT 3.5 build:

This is a tall array of drivers. Unlike smaller 2-ways, this system needs a bit more distance to properly sum. The image above shows what happens when you get too close - the midbass and upper midrange starts to droop a bit. This is because of the relative distances between the drivers. When you're 1 meter away from the tweeter, you're off the axis from the lower woofer at a 30 degree angle, and it's a few inches further away which affects the phase relationships. It's not too bad but it does affect the tonal balance. That issue, along with the full baffle step compensation means this system needs a medium to large room to fit the 2.5 meter listening distance. I'd 2 say meters minimum, but more distance is better.

I was measuring at 1 meter. In my case, 2.8 meters did the trick - and, as I now remember, that was around the distance I used for my simulation (actually, 240 cms). Now the measurement tracks the simulation very nicely.

I also did tests with the RTA.

At 1M things are pretty flat looking.

At 2M, things aren't looking that good in the midbass and midrange. They are depressed.

At my listening position (around 3.8 meters), it's pretty chaotic - I have the 3 and 6 KHz bumps, a null at 200~400 Hz and lots of other artifacts.

All things considered, it's pretty much a miracle how much our hearing compensates for all of this

[dlr]

Can you please share the link? It seems like an interesting discussion.

Here you go:

flat-not-correct-stereo-system

All things considered, it's pretty much a miracle how much our hearing compensates for all of this

And what it tends to let us think is happening at times.

Dave

[Silversmoky]

Javier, did you ever get these dialed in where you were satisfied with how they sound? I was just reading back through your design here especially to see how you liked the little SB Acoustics dimple tweeter.

[fjhuerta]

Yeah, the room was the problem. The speakers were fine! No speakers I've used in this room sound fine, there's just too much glass and metal around. Nice to look at, terrible to listen to music in.

[Silversmoky]

Thanks Javier. Glad to hear you narrowed it down to your room. Sometimes it is shocking how different the same speaker can sound from room to room. Was just curious how you ended up liking this tweeter? I am considering it in a new brain storm design and on paper it seems like it will fit the bill nicely just wanted to get some feedback from someone who has heard it in person a bit.

[fjhuerta]

FTR I love the tweeter. Its my favorite dome - beating the 27TBFC I liked so much.