4 ways active floor standing project

[faina]

Experts,

I’m trying to build a high end floor standing speakers (plus a central later), and I’m not sure I’m on the right direction… I’ve studied a lot, with the only result to make me more confused…

I found your forum very inspiring, and I hope you can share your experience with me

What I want to do: 2 floorstanding speakers (+ 1 central later) with the most natural sound possible. I want seat and listen the real instruments and voices, nothing too “cold” (like the B&W speakers under 5k USD i.e.) or too flat. Here the draft for the floorstanding. The central will be a match later.
I need a speaker that “rock” as well, because I listen electro and rock at high volume sometimes…
My amp now is a Marantz SR7002, that could be used as pre-amp or direct with 150W per channel.
For the design I have the maximum flexibility, so feel free to make any recommendations. I’m thinking to drill the angled panels for use better the cabinet volume (dimensions in mm).

Here my (many ops questions:

1. What do you think about the drivers choice?
a. Scan Speak r3004-662000D
b. Scan Speak 15m-4531k00
c. Scan Speak 18w-4531g01
d. Scan Speak 18wu-4747t00
Is a 4 ways too much (I want cover as much as I can the frequencies)? Are there drivers with same quality for less price, or better quality for a small price increase? Can I have the same result with 3 drivers?
2. Crossover: I’m thinking to make the speakers active, using the miniDSP (1x4 or 2x8?) and the miniDSP mic for measurements. Is that a good idea? Is perhaps better passive (but looks like the design is complicated and more expensive) ? my amp can bi-amp, so in theory possible..
3. What I can use for amp the drivers? I read some good review about the ICEPower but looks like it is too cold and difficult to get. I would have a “one button all on” system. I think I can even buy something Yamaha HI-FI base amp for every 2 drivers (like tweeter on left channel and mid on right, etc.) but they are big, heavy and I can only put them at the bottom of the speakers… still don’t know if that make sense. Or car amps with audiophile spec, if they exist at reasonable price? i.e., how I define the volume of the various amps in case of amp module without volume pot? Adding a pot is always possible?
What about Hypex UcD180HG with HxR?
4. What’s the best frequency cut for the drivers, or what’s the best way to define?
5. What’s the best filter for the crossover? Looks like it’s the linkwitz, but again not sure
6. In my case, is better 4 ohm or 8 ohm speakers?
7. I downloaded the scans speak toolbox: below the results, but not sure how to use properly for my project
8. If I go active, do I need to protect the tweeter with a 10 microfarad resistance in series?
9. Is better amps with thermal protection right?
10. If I leave always the amps on, are the drivers go to overheating?
11. If I buy the amp card, for ground them is an aluminium frame enough?
12. I want put some “cone” like in the anechoic chamber on the angled panels and compressed wool between that panels and the vertical/horizontal one: do you have better recommendation?
Bitumen sheet on all the internal walls
13. What do you recommend for cabinet wood material? MDF is good enough or plywood is better? Now is 15mm but I can make ticker.
14. I plan to cut the front panel in the between of “driver box” for avoid vibrations: is that a good idea or a waste of time?

I listened a lot of speakers in the shops, some VERY expensive (>10k USD a piece), and 90% of them are really not close to reality IMHO; looks like they are trying too hard to get us say “listen the violin” or “listen that voices”, forgetting that their scope is report the sound as in a natural environment

For your information, I live in Japan.

Thanks in advance for your great help ;x( and I hope my post is not too messy…

[faina]

[---k---]

Please don't take offense to this, but speaker design is a hobby that requires a lot of experience to be successful at. As you've noted, even some big speaker companies with huge budgets and paid full-time designers sell speakers that don't perform up to your liking.

The project you are proposing is very complex and ambitious for a first time designer. It would be like trying to drive in an F1 race the first time you ever got behind the wheel of a car. There is a reason you don't see many 4-ways speakers; design complexity being one of them. Your questions 4 and 5 are really unanswerable, because they are dependent on the driver selection and other project goals.

I would highly suggest you consider starting with a simple 2-way Tweeter-Midwoofer (TM) design. I think this exercise would begin to answer your questions.
JonW's Spassvogel thread may be a good walk-through of the process. http://www.htguide.com/forum/showthr...-amp-18W-8531) It uses a passive crossover, but many of the concepts would be the same.

You might even want to consider building one of the existing designs found in the Mission Accomplished subforum or somewhere else. Build a known good, high quality design. Build it with the passive crossover first. Then buy the MiniDSP and see if you can replicate the sound with the MiniDSP. I think this exercise could be very informative and teach you what you need to learn to build that ultimate dream system.

I wouldn't worry about the amps at this point in your project. The speaker needs to be right first. Amps will be a fine tuning. With an active crossover, you'll need an amp for each driver. So, if you are doing a 2-way, a stereo amp for each speaker might work nicely - the right channel for the tweeter and the left channel for the midwoofer.

MDF if fine wood to work with. Most of the project's you've probably seen use it. It creates a lot of fine dust when cutting that can be messy and difficult to breathe. I use high quality plywood for mine. The choice in wood is less important than the size of the panels, the bracing, etc. 15 mm is slightly less than the 3/4" we typically use here in the States. There is nothing magical about 3/4", except it is readily available. 1/2" tends to bend. So, braced 15mm is probably okay for small panels. You might want to consider doubling it for your front baffle, like you see in many of our projects.

[JonMarsh]

A lot of stuff to look over here, and I'm just heading to work, so not much time.

Two things stand out-

the 6620-00 tweeter- due to it's waveguide like front plate intended to increase the HF dispersion, it has something of a bump in the response in the top end, which I found I didn't like- I ended up replacing it with the 6640 Be tweeter- a good alternative for more reasonable budgets is the 66000.

Dual 7" woofers? Is this actually a 3.5 way? That's an unusual paring with different SS mid woofers. If you're actually doing a straight four way, why not an 8" or lager woofer on the bottom?

BTW, haven't had my coffee yet either, but the comment on the tweeter stands... regardless. :W

[faina]

JonMarsh,

thanks!!! The tweeter you recommend is the D3004/664000? If yes this is a little over budget at 500 USD a piece... or is something else?
about woofer: what about 26W/8867T00 or 22W/8857T00? Larger better?

Ryan,

no problem at all, I'm here for finding help I forget to say that this is my #6 project. All the previous was based on high end 3 way car kit (with XO) mounted in close cabinet using the data on a speaker construction book, loooong time ago. Some of them were used as professional audio system in swimming pools, some still running happily at my parents home.
What I want to do here is move to the next step. I'm a little bit against passive XO after I read all the article from Mr. Elliot. I'm an engineer and I prefer have a precise approach
After Mr. Elliot article, looks like you can define the best frequency range of a driver using the graph. Except for the tweeter, the curve looks very similar to me, and I don't know how to use the resonance number for define the best driver working range. Do you have any example please?
I look to all your project in your website as well

I understand until now that DSP + Hypex amp can be a good quality solution and the wood cabinet is 15mm

Looking forward to your answer!!

cheers

[meb46]

Faina,

I would reinforce Ryan's comments and caution you on the complexity of a four-way. There are a huge number of designs on this forum that use a three-way design with some fantastic results... and could save you some hard/expensive errors in the process. I had initially started with very ambitious four-way designs and ended up with a three-way (a complex one at that)... it remains an evolution, and Jon has been a massive help on getting these to where they are at today. If I was to do it all over again, I would still go three-way with a passive crossover s mine currently are. The costs of a four-way with active crossover will go very high considering the requirement for so many amplifier channels. If you want a high end solution, even good passive crossovers can go into the thousands of dollars... just depends on your preferences. Don't under estimate costs, time and frustration levels.. triple your estimates of all three and you will get close to what reality is... but is thoroughly great fun

Good luck!