3 Ways Compact Speaker Building Advice

[letiennam]

Hello all;
I'm looking for some friendly advice for my speaker building project...
My current and long-time speaker project consist of
Scan Speak 18W/8531G-00 mid-woofer
Dayton RS52AN-8
and 1 tweeter needs to be selected. I'm leaning towards choosing SB Acoustics SB21RDC
Years ago I thought I would pursue an DIY compact 3ways speaker project but II spent a lot of time on jobs after graduating from college, these speakers have been in the storage for a very long time.
Now I have been bitten by the idea of building these speakers once again. Pulling the drivers out of storage, I discovered they are pristine.
After consulting I have 2 ideas as follows:
1. The general design would follow the Tony Gee L'ofeo speaker, which I find quite aesthetically pleasing. It has a volume of about 35l and is designed for SS 18Wu but I will edit to reduce the volume to about 30-32l by reducing the depth a bit to suitable for SS 18W8531. The tweeter will be mounted on top of cabinet.

2. cabinet designed based on troels Gravesen SP44. tweeter and mid will use driver i choose.

Since I lacked the requisite knowledge and experience measuring to design my own crossovers. but i already have behringer ecm 8000 and i can learn gradually. I can also use CNC service very close to home to quickly have a cabinet
I’m looking for suggestions can make any kind of informed decision.
Much thanks

[JonMarsh]

Hello! This can be an interesting and nice project, but of course there will be something of a learning curve. Two aspects to the learning curve are the fabrication of the enclosure and the measurement and crossover development.

With regards to the enclosure, I suggest you talk to the fabrication team you have chosen and find out in detail what design inputs they require for successful construction- particular preferred file formats. You will want to work out all the details which would be desired in the front baffle, including items like rear baffle bevels for the driver openings, the rebate diameter and depth and through hole.

Now, for an Avalon like design, with thick front baffles, this becomes even more important- also, you should model this and discuss with them if they have the means to implement the facet bevels. If you refer to the Ardent, Wavecor Ardent, Kurosawa and Ardent D topics, you can get some "hints" about ways that can be done. This can involve simple custom built fixtures with a large cutting depth table saw, or 12" dual bevel sliding miter saws, or skill with hand held power saws and Japanese manual saws.

There are ways you can use an ECM8000 microphone, with freeware PC software like ARTA, but I would tend towards recommending Pocket CLIO (if it's in your budget) as it includes all tools in a unified environment for acoustic and impedance measurement, with known level calibration of the microphone. It runs on both PC's and Macs. I have this system, but also have another test cart equipped with wider frequency range microphones, using Fuzzmeasure for acoustic measurements and data export, and DATS for impedance measurements with data export. The wider upper range is essential for evaluating 20kHz plus behavior of tweeter, and capturing distortion data accurately. I normally test at 88kHz sampling rate, which gives me good data to 40kHz.

Fuzzmeasure has many operational modes for acoustics tests as well as a speaker test mode; and has much more flexible windowing functions to support adjustment of time domain data and exclude room reflections. I've been using Fuzzmeasure since its creation- but it is a Mac only software- it uses many of the Apple software API's to enable functionality; Windows equivalents don't exist. For measurement computations and design synthesis I use VituixCAD, on both a 2015 Mac Pro running Windows 10 and on an LG Gram 17. The portability of the LG is often useful, and the screen resolution and size hits a sweet spot for using VituixCAD- the Mac Pro runs on a 4K 43" monitor. Font and UI scaling is not a problem on a 4K monitor of that size, but a 4K 15" monitor like on my Dell XPS15 is problematic- (it was bought originally as the controller computer for my Audio Precision APx555, but the LG Gram works better in that application, again due to screen dimensions versus nominal resolution.)

Now, regarding your drivers:

The RS52AN has had some quality issues; I used it successfully back in 2007, but recent samples have a resonance in the surround that shows up clearly in the swept impedance curve, and unfortunately in the measured response. You need to check yours out. Refer to the Ardent D topic for more information about that. I ended up going with a Morel party, but at the time I would recommend the 3" dome mid BlieSMa T74A-6 for most folks; I'm going to retrofit my Ardent D's with T74B-6, the Beryllium version.

Going with any extended range dome mid, you have more options on the tweeter crossover side, and I'd give some thought for a "budget" tweeter approach from SB Acoustics with the SB19ST. I'm using that in a compact three way CC design, which of course could be converted to a more "normal" three way system. The midrange is an SB12MNRX25-4; I have some stock on them, but I have seen them harder to get from some vendors lately. Alternatively, I'd suggest the Faital 5FE130, which is being used in the larger CC concept (with 7" woofers instead of 6" woofers) and the same tweeter, or possibly the PT-2522 mod I have come up with).

Here's the deal on the SB19ST- note the off axis response:



This part is a real "unsung gem" and a bargain, too.


please look into these ideas and comments, and of course get back to us for follow up.

[letiennam]

Thank you for your suggestion
so sad because the cat accidentally damaged my SS 18w8535. I'm going to switch to a new option.
Dear JonMarsh, could you please share the front baffle drawing or the entire original design of Ardent. I also have drivers SB17cac-8, SB26CDC, and dayton RS52AN-8. I have read a lot about Ardent D. I think my drivers will be a cheap option for Ardent or Ardent D. Currently, I have not found any retailers in stock DA25TX00-8.

https://www.htguide.com/forum/mission-possible-diy/project-development/43201-ardent-d-aka-kurosawa-jr-winter-camp

[crackyflipside]

I used the RS52, one mistake I made was having it share the same air space as the woofer. It is not completely sealed off in the back, and I hear distortion through the mid from the woofer when running my speakers sealed.

[letiennam]

Thank you. I will follow Ardent's style. so the RS52AN will be in the entire front baffle. so it will be in a compartment independent of woofer