first bookshelf diy

[mazurek]

I am making a bookshelf for the first time, and was thinking about copying the A4 Monitor SE-4 at

http://www.audiocomponents.nl/speake...erence_eng.htm
IE.

8531G + 9700 in .75 cubic feet enclosure

I am not sure whether their cabinet is sealed or vented, and I would like a sealed cabinet, does this make a difference with the crossover?

Is it a better idea to copy the diy crossover design even if I change the box, or have Madisound make a LEAP crossover?

My listening room is my living room, and I was wondering if 87 dB sensitivity is loud enough to also watch movies at a comfortable volume. (8531G has 87db sensitivity and 70W power handling)

From reading the forums I get the impression Scanspeak drivers, in particular the 9700, are detailed but easy to listen to. I find that mid-hifi speakers make a lot of rock music less enjoyable, would anyone describe the scanspeak drivers as harsh?

Thanks a lot for your time.

Lee

[Emiel]

Originally posted by mazurek

I am not sure whether their cabinet is sealed or vented, and I would like a sealed cabinet, does this make a difference with the crossover?

Lee

The cabinet is vented, as can be seen on drawing 1 (http://www.audiocomponents.nl/speake...Mon-SE-4_1.htm) on the site you refered to.
When making a closed cabinet with this driver, you'd probably miss a lot in the lower frequency region. You can simulate this in WinISD for example.
I don't think you'd need to change the crossover (http://www.audiocomponents.nl/speake...Mon-SE-4_1.htm), maybe some impedance correction or something, but I don't know too much about crossover design.
I could help with the translation of the text on the drawings (I speak Dutch) if needed.

BTW, I did an AB comparison of the SS A4 monitor with the Vifa Premium 11 (http://www.audiocomponents.nl/speake...remium_eng.htm) and found the Vifa more transparant and detailed. The A4 was a little more laid back and "dull". IMO the Vifa also has more realistic mids and thus was the better speaker of the two.

Kind regards,
Emiel

[mazurek]

Thanks for the suggestion. I left out a part of the problem description, I am also making subwoofer-speaker stands. I think they should go up to 200 hz no problem (Dayton Reference 12) given preliminary testing, and they have a plate amp that can crossover up to 160hz at 12db/oct.

My somewhat crazy plan is to sell my Martin logan mosaics and use the money to build some high end monitors, so I'm looking to get the most rocking hifi bookshelf speakers I can get for about $1200.

Do you have any insight into the character of the various kits, I don't want a detailed but harsh speaker. That was one of the supposed advantages of scanspeak over for example seas magnesium mid ranges. Is that particular model dull due to the crossover, do the 8545 kits also sound dull? I'm really looking for something that will accomodate rock, punk, and all non-jazz genres.

Would smaller midranges in the 5.5 inch range perform better, I've seen excellent reviews of the ACI saphire xl.

I apologize if any of these questions are stupid beginner questions that I should solve myself. I was hoping that, if I follow the advice of smarter people, and pay for crossover design, I might be able to build something that is at least as good as my current speakers.

[Emiel]

Originally posted by mazurek

I apologize if any of these questions are stupid beginner questions that I should solve myself.

Please don't apologize! You've obviously been reading this forum and are still left with questions, don't bother too put them out here, thats what this forum is for!

Originally posted by mazurek

I was hoping that, if I follow the advice of smarter people, and pay for crossover design, I might be able to build something that is at least as good as my current speakers.

I'm not that smart when it comes too speaker design, but there I can share some of my experience.

The single most important factor in speaker design IMO is listening. Talk some CD's you know well to a store which demos DIY speaker kits and listen, compare and have a chat with the guys over there (don't forget to bring lunch ).
Reading 'The Loudspeaker Cookbook' by Dickason gives a lot of insight in speaker design on all different configuration.

I read it's your first project, so maybe you'd better stick with a kit then design a speaker yourself. You could do some tweaking with help from the guys over here.

Originally posted by mazurek
I think they should go up to 200 hz no problem (Dayton Reference 12) given preliminary testing, and they have a plate amp that can crossover up to 160hz at 12db/oct.

You'd probable want to cross a little lower (say 130Hz) to make sure there's no coverage of voices by the woofer. When making a monitor with a closed cabinet (or even open baffled) you'd probable need a 5" or larger mid. But simulate this in e.g. WinISD to make sure of the driver gets this low in a closed config.

I recently listened to the (at that time still under development) Scan Speak Maxima. (http://www.audiocomponents.nl/speakers/new/index.htm)
It's probable one of the best speakers I've ever heared. Detailed, but way from harsh, and not "dull" as the A4. It uses the D2904/7000 ringradiator and two 15W/8530 in a MTM arrangement. (Pretty expensive parts )
So my advice: LISTEN!

Kind regards,

Emiel

BTW, there are no stupid question, only stupid answers (I hope this isn't one)

[mazurek]

Thank you very much for the detailed reply. "The loudspeaker design cookbook" is in the mail as I post, so hopefully I can get up to speed.

One more question about building a bookshelf monitor. From what I have seen people cross the midwoofer to the tweeter, but I don't see anything necessarily about a highpass on the midwoofer. Do I need to make sure to highpass filter the midwoofer also so it can integrate in with the subs, and limit the cone excursion? I know there is a 12 db/oct dropoff on sealed boxes, but WinISD shows huge cone excursion in low frequencies for a typical 6.5" driver.

If I do place a highpass filter, for example a 12db butterworth to make a 24 db/oct acoustic rolloff, does the frequency center go at F3?

Thanks a lot, hopefully I'll be able to answere more of my own questions once I get my book.