• 02-17-2005, 08:57 AM
    phatbass
    More Mods to the AR.com speakers
    Hi I am seriously looking into a set of the AR.com speakers. They seem to get amazing reviews. After looking at the design for a while, I have two things I would like to try/change if they sound good to people here and Ed Frias.

    1. Why not round over(1/2" round?) the edges on the front of the cabinet to reduce the edge diffraction?

    2. I would also eventually like to make these speakers active, for a few reasons. 1. it would make the speakers probably about 3db more efficient. 2. directly coupling an amplifier to a speaker is much better than running the amp through a crossover(mainly the inductors and large capacitors). 3. the crossovers in an active crossover are smaller and can be matched to each other with a lower degree of error.

    Any opinions or thoughts would be greatly appreciated.
  • 02-17-2005, 09:05 AM
    kexodusc
    The 1/2" round over is fine...lots of people have done this I believe...I actually used a 45 degree cut just to be different, couldn't hear a difference between the flat baffle and the 45 cut. My cousin rounded his over though.
    In hindsight, I prefer the rounded edges...easier to veneer.

    The jury is very much out on whether rounding the edges really produces an audible benefit, despite Dennis Murphy's findings...I'm not sure this will translate into a performance improvement.

    As for making them active...sounds really cool, but also a lot of work for an inexpensive speaker...I've never done an active speaker before, but presumably, at some point you're going to have to employ the filters or have a crossover anyway, aren't you? I don't think degree of error in the crossovers is anything to worry about...
    I'm not sure what real benefit you'd gain by this as far as sound quality goes. Maybe you could explain?
  • 02-17-2005, 11:39 AM
    EFE Speakers
    Active crossover?
    phatbass,
    A lot of guys believe in active crossovers for several reasons and some are valid. But the problem with doing so with a speaker like my DIY is, you won't have the same crossover and it will definitely sound different. You can use an adjustable active crossover and play with the frequency, the slope and the volume of each driver, but you end up being the designer of the crossover and it no longer is the Ed Frias DIY, but rather a DIY only using the same drivers!

    The reason why the DIY has received such good reviews is because of how the crossover was tuned in the first place, and using an active crossover will most likely not sound as good, unless you can adjust the crossover point, the slope and the efficiency of each driver exactly as my original crossover was designed with. In my opinion, don't waste your time unless you want to experiment and design your own speakers. Then you have no way of measuring how accurate they are unless you have some measuring equipment, and that leads to another major factor, how to measure the speakers?

    As for rounded cabinet edges, I believe the new Madisound DIY cabinets include them already. I would suggest just buying their finished DIY cabinets with their crossovers. When is comes to the interior insulation, e-mail me for the proper type and amount, Madisound doesn't follow my specifications on this issue. Success!

    Ed Frias
    EFE TECHNOLOGY Speakers
  • 02-17-2005, 02:17 PM
    phatbass
    Thanks Ed and kexodusc for the replies,

    Here are some quotes from various articles and people about active crossovers that I have read. For the measuring I have a calibrated measurement mic, and some RTA software(true rta). I could measure the speakers in my room with some absorbtion pannels placed near them to measure them, or I could also set them up outside for measurement.

    BTW, the signal would come out of the reciever or preamp, to the active cross over and then the different signals would go to different amps and then to the individual drivers.

    "The technical reasons for the superiority of this setup could take pages to list, but basically a passive crossover presents a complex reactive load before the signal ever gets to the speaker drivers. The passive components are wasteful of power and add significant resistance in-line with the woofer. This destroys a great deal of the damping factor of a good power amplifier. I could go on and on, but suffice to say, the benefits are extensive. Also, you can use power amplifiers that suit the particular frquency band to be reproduced such as a smooth tube amp for the highs and a good, stiff solid state amplifier to control the woofer."

    "1. Removal of the Passive Crossovers improves phase shift, delay, voltage ringing in capacitors, inductor compression, complimentary induction between inductors, compression from heat generation in resistors and capacitors, variances in component values (usually +/-10%) and decoupling of the amp from the driver.
    2. Each amp only amplifies the signal appropriate for the driver it is attached to. A terribly loud bass frequency will have zero effect on the treble amp and bass induced treble clipping is virtually eliminated.
    3. Since the effective damping factor of each amp is greatly increased with the removal of the crossovers, the speakers will respond more accurately to the signals. This is especially noticeable when the signal stops and the cones stop as well. With non-active setups, the cones might continue vibrating from the inertia generated. "

    "Active crossovers enable simple and direct amplifier-to-speaker driver connections, and totally eliminates the passive crossover inside the speaker. Passive crossovers are very wasteful of energy, and the necessary inductor that is in series with the woofer of every speaker with a traditional passive crossover network introduces resistance in the line that harms the otherwise good damping factor of an amplifier. Passive crossovers present the power amplifier with a complex, reactive load that unnecessairly burdens the output stage of the amplifier. This can create various distortions in addition to making the selection of cabling more critical than it needs to be.

    Active crossovers enable the selection of power amplifiers that exactly complement the characteristics of the speaker drivers and of the frequency ranges to be reproduced. In my instance with extremely efficient horn speakers, I use a solid state amplifier for the woofers to take advantage of their damping factor, and use a single ended triode tube amplifier for the high frequencies, which totally eliminates any distortion caused by a traditional push-pull amplifier stage.

    Active crossovers completely eliminate any clipping distortion from the woofer amplifier from affecting the high frequencies and vise versa.

    Active crossovers enable YOU to determine the nature of the sound of your speakers, not some manufacturer. If you want to change the sound quality, YOU can do it, and very simply.

    There are many other advantages to active crossovers that I'm sure others will post, but the bottom line is that if anybody is interested in making a real improvement in a system and doesn't mind doing some DIY work, active crossovers are the way to go.

    But I must stress, implementing them is not something you do on a whim. It takes some serious work and dedication, in addition to arming one's self with the appropriate knowledge. It also requires the purchase of an RTA program and a calibrated microphone so that the system can be balanced."

    These are three different people who said this stuff, so some of the information was repeated. Again this is all theoretical right now. I am still finishing up a diy subwoofer. After it is done I do plan on making some speakers to compliment it. I would probably build these with the passive crossovers, and then maybe move them over to active speakers down the road. I was just interested in what Ed thought of the idea.
  • 02-17-2005, 05:19 PM
    EFE Speakers
    phatbass,
    After writing a 35 minute response to your response, when I pressed the "submit reply" button and it all disappeared, so I guess it was not meant to be??? I'm not going to go through all my responses again.

    I'll just give a summation in this response.

    If active crossovers were so superior to passive, many high-end speaker manufacturers would use them, but the fact is, only a few do! Meridian has been working on both active and digital crossover for years. Their speakers are expensive and really don't produce any better sound than many of the well know passive crossover speakers out today, in fact they are inferior sounding to many. If you don't get a active crossover correct, they actually can be worse!

    Use a good high current amplifier with a well designed passive crossover and the problems you spoke of all become a mute point! If in deed active crossovers were so superior, many (not just a few) high-end speaker manufacturers would offer them, but you see very few them because the cost to results don't prove to be worth it, that should tell you something!

    Your idea to build both a passive and then active is good. After trying the passive and then the active, be honest and let all of us know the results you come up with. Success!

    Ed Frias
    EFE TECHNOLOGY Speakers
  • 02-17-2005, 08:01 PM
    phatbass
    Ed, sorry to hear your post got lost, I hate that when that happens....

    Active crossovers have been used in many speakers. Almost every good studio monitor is active, also a lot of professional speakers are as well. Paradigm used to make active versions of the studio 20 and 40. M&K makes active speakers, Dynaudio, and a few others do as well. I am not trying to say if it isn't active it is crap, I am just saying that a well done active setup is sonically appealing.

    Also a well designed crossover is something that certian manufacturers do not use. Most of the mass marketed speakers use a decent design with junk capacitors and inductors rated at +-10% similarity. I recently replaced the capacitors in my JBL speakers and what a difference it made. There are also many companies who do it right, Paradigm, B&W, and many others. The crossover is one of the most important parts of the system, it can make or break any speaker.

    I plan on ordering the kit soon, it will probably be a while before I will be able to make them active due to time and money restraints. But when and if I do I will be sure to post back my results.

    Thanks again for the reply and the advice. It is highly appreciated.