MtBiker - I wonder if you could discuss your design decision to use dual 8 inch woofers. Your chosen woofer 22W8857 is an excellent driver. A pair of them per side is over $1200 investment for all 4... Did you consider, at any point, using a single 10 inch per side?
I am asking these questions so I can benefit from your experience. Eventually I will upgrade my active system, and I want to be as knowledgeable as possible when that day comes.
I am asking these questions so I can benefit from your experience. Eventually I will upgrade my active system, and I want to be as knowledgeable as possible when that day comes.
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Outstanding design and awesome execution. Looks amazing hope it sounds as good as it looks. I have a project coming up with same dual 8 and sb acoustic tweeter and mid but all passive crossovers Still trying to convince my wife it may be the LAST speaker I build (but it never is lol) but this is my only addiction
At least it's an addiction your wife benefits from.
I did a pair of 8's because I wanted to see if it helped smooth out floor bounce. Then I centered them for aesthetic reasons, and because I was not certain where I wanted to cross to the mid or how far away was acceptible. What I found is that the dual mids may have made floor bounce worse by spreading it over a wider frequency range. So instead of narrow and deep, it may have become wide and shallow. Unfortunately, it also happens in a range (~100-200Hz) that is difficult for me to get measurements I am 100% happy with (outdoors, indoors, indoor LP/MMM), and I have SBIR problems in my listening room right in the same band. As is, the speakers sound "right" to me, and any EQ applied to this range to combat any one measurement worsens any other type of measurement and sounds "wrong" to me.
If I were to do it over, I would
- Use a smaller mid to improve DI at the tweeter crossover.
- Simulate mid excursion to determine a range of acceptable lower crossover points.
- Simulate different M-W crossover slopes at different distances to determine where the woofer can be placed.
- Determine the floor bounce frequencies of both mid and woofer at the LP and determine an appropriate crossover frequency.
- If the woofer can be pushed to the floor, that would be ideal as it would eliminate the woofer floor bounce.
I think they still ended up being at least a contender for the best speakers I have ever heard. And with some minor design or execution issues, it means I can start thinking now about the next "last speakers I ever build."
For example, with the success of the force cancellation in my push-push sub, I would like to figure out how to do push-push or push-pull woofers >80Hz, but still package them in a small cabinet cabinet with no in-band cavity resonance.
I think I meant to reply to you instead in my last post
Since I went active and didn't need to worry about matching the sensitivity of the remaining drivers, a single 10 could have been used. That definitely would have saved some money.
I thought it might be nice to design something that does not need a sub, and I did achieve that. However, they are out in the room while my sub is centered on the front wall, and <100Hz, the sub measures closer to identically at all positions along our very long couch. This has led me to the conclusion that no floorstanding speaker needs to be full range. Instead, you just need to make sure you have enough headroom >80Hz and a single 10 would have been plenty.
Not speaking for OP, but aesthetics does come into play at some point. I find slim tower style designs like Focal and Avalon look better with dual woofers than with single. And, 8" tends to look more solid as a 3-way woofer than a 6.5 does. This design is very similar, and I think a single 10 would look a bit clunky in this design - forces the baffle to be wider, or else you have to taper the baffle - either of which would be a definite deviation from the current design.
In contrast, I think designs like the Sonus Faber wide-baffles (Ellipsa, Stradavari) actually look better with a single woofer rather than a double.
So, there might have been a less expensive way to satisfy the aesthetic demands, but it's tough to argue with the result.
That is a very valid reason, and I have always believed it would help.
I think in the long run you may find that "wide and shallow" is easier to deal with. I remain convinced that spaced woofers help with floor bounce.
This mirrors my own experience. I have a hard time getting believable measurements in the 100 to 300 hz range. This is what makes a 3 way speaker so much more challenging than a 2 way... that woofer to mid crossover is difficult to get right. I have a -6 dB suckout at 220 Hz that is almost certainly a floor reflection.
My attempts at using eq to handle floor bounce cancellation in the 220 Hz region has resulted in good measurements, but a poor sound quality... it sounded muffled and unfocussed. Similarly, attempts to apply room correction below 120 Hz have been disappointing. They always sound wierd. "slow and off-tempo" is how my wife described it. I have not given up, but I know I am doing something wrong.
I have been trying a variety of crossover slopes. I am using an IIR DSP, so all my crossovers are classic frequency+phase deals. I keep coming back to LR4. Everything sounds real, focussed, and 3 dimensional.
I want to try a Harsch crossover on the woofer-to-mid. It will be my next experiment.
That is not hard to believe. My system has exceeded every expectation I had.
Is your LP out in the room or against the back wall? By necessity, our couch is against a wall. Yes, it means we get back wall reflections that I can see in the IR, but it also means we sit in a high pressure zone which reduces the load on the subwoofer. More importantly, the room response <100Hz does not change drastically along that wall, and it makes applying room correction very beneficial.
If you go into REW, generate min phase, and look at the excess group delay, anywhere it goes off the rails, you should avoid corrections because you are dealing with a room reflection. Where it is flat and near zero, you can correct all you want. Here is what my LP looks like.
Are you trying to do a TP crossover or just cut the woofer more abruptly to avoid a resonance? When I switched from IIR to FIR (TP), I was not able to tell a difference I could attribute to TP. I think there were too many other minor differences I introduced at the same time. I also tried FIR corrections to IIR crossovers, and while the made a dramatic difference to the phase response and step response, it was far from the perfection I got first try with FIR.
Great advice... I have not yet experimented with REW... it is on the list of things to do, and perhaps it should move up higher on the list. My woofer cabinets are not really subs since I cross them at 200 Hz. I planned on a crossover somewhere between 150 and 250, and so far it seems 200 is the sweet spot.
I want to try a Harsch crossover mostly out of curiosity. Interesting that you could not directly detect a difference or improvement due to transient perfect operation. I have always suspected that I might not be able to hear it either, based on my experience in the past with transient perfect speakers (Theil CS3.6 and Vandersteen 4). Some people can really hear this, others like me not so much. One of the reasons I went with active DSP crossovers is the ability to experiment.
Once again, hats off to you for an outstanding build. If a person wanted to buy what you have built, it would probably cost them north of $40k.
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