• 01-20-2005, 05:53 AM
    Free USA Shipping
    AR.com DIY Speaker Modifications
    Last week I assembled the AR.com DIY speaker kit from Madisound and have them broken in after about 20+ hours of use. I've not made any modifications yet but I just ordered acousta-stuff from PE to replace the foam Madisound provided in hopes this will clear up the mids and add to the bass.

    Also, I want to add a 3, 4, or 5 ohm resistor to tone down the tweeter and correct the sibilance, but I'm not exactly sure how to do this. I've already purchased these resistors from Madisound. Please describe in layman's terms how to do this. Thanks!
  • 01-20-2005, 07:03 AM
    kexodusc
    I'd advise against the Acousta-stuff...in this particular design the interior is not meant to be overly dampened...you could end up killing the midrange smoothness and add excess boom to the bass...I had some left after building the PeeCreeks that I tried out briefly. It works fine in the PeeCreek but not in the ar.com DIY, to my ears. Too much dampening will really kill off the natural sound and transient responses in my opinion. If you're having issues witht he mids and bass (which are this speaker's strength considering size and price) it's most likely something else...

    I have no excessive sibilance on mine with the standard 2 ohm resistor (7 ohms) total, but then again, I have these beside my Paradigm Studio 40's which are bit bright IMO.
    Search some of the other threads, Ed answered the resistor question just a few days ago here!

    Also, how do you have them placed?
  • 01-20-2005, 07:31 AM
    Free USA Shipping
    I read the posts by Ed Frias a few times but I can't piece together what I'm supposed to do. I was hoping for a less technical or more complete explanation in layman's terms for how to add a resistor.

    I have them sitting on top of a pair of 38" floor standing cabinets, of course not ideal, but I doubt it's attributable to the undefined mids and bass. I'm sure I will be removing the Madisound foam and trying a handful of the acousta-stuff in each speaker at least to see if it helps.
  • 01-20-2005, 08:04 AM
    kexodusc
    Try emailing Ed directly, I won't dare try to step you through it.
    I'm really worried about this "undefined mids and bass"...something's not right...everything wired in phase, no damaged woofers? Did you use Madisounds crossover or assemble yourself? How much polyfil did you install?
    Just curious, what are you use to listening too as a reference?
  • 01-20-2005, 11:50 AM
    Free USA Shipping
    Quote:

    Originally Posted by kexodusc
    Try emailing Ed directly, I won't dare try to step you through it.
    I'm really worried about this "undefined mids and bass"...something's not right...everything wired in phase, no damaged woofers? Did you use Madisounds crossover or assemble yourself? How much polyfil did you install?
    Just curious, what are you use to listening too as a reference?

    Instead of first emailing Ed, I thought it better to post here so perhaps someone with the same question some day may benefit.

    Although I don't know how to tell if it's wired in or out of phase, I'm certain I wired everything as diagramed and the woofers aren't damaged.

    I'm using Madisound's crossovers and the foam fill Madisound provided. I'm guessing the replacement of the Madisound foam with acousta-stuff will clear up the mids and add to the bass (which is surprisingly low).

    For reference I've listened to 4 different CDs with which I'm very familiar. For two weeks before I received the AR.com speakers, I listened to the same 4 CDs with a pair of Ascend CBM-170's. I sent them back since I could not live with the tweeter's high end and sibilance. As is the AR.com's high end and sibilance is much less objectionable than the Ascends. However, I'm hoping these mods will bring my AR.com speakers up to their potential.

    Thanks
  • 01-20-2005, 12:10 PM
    kexodusc
    I see the problem...the foam fill madisound includes is definitely not what should be used. You are not just dampening the cabinet, you could also be effectively increasing it's apparent volume (do a google search to find out why, I'm not the best to explain this to you).
    The design calls for polyfill...polyester stuffing, like you'd use in pillows...3 inches deep from the back wall...good news is a $5 bag will do about 3 pairs of these speakers...go to Walmart and buy some, try it out....then, if you still aren't happy, we can try a few other things. I'm fairly confident the polyfill will help
    Good luck.
  • 01-20-2005, 03:49 PM
    dave_bullet
    Hi FreeShipping and others... Here's my progress.

    1. Bass - As Ed suggested, I've removed a lot of my dacron batting - I had way too much in there. There is more defined bass. So much so, that I thought my sub was on when infact it wasn't! (I have my sub volume quite low for music). I'd definitely say the speaker has the right about of BSC now (it seemed a bit thin / lean before). I only have about a 1" think (and sparse at that) layer on the back wall behind the mid-woofer. I don't think I'm getting any more midrange leakage out the port but further listening will tell (having a rear facing port here is good aspect of this speaker IMHO).

    2. High end sibilance - I've added another 2 ohm resistor to each tweeter. (So now I have a 5 ohm/4 ohm combo - not the 5 ohm / 2 ohm that comes as standard). This has helped a little - but not much. I modelled the change in Speaker workshop which confirmed what I thought my ears told me. an extra 2 ohms only seems to have a 1dB decrease (which to my ear is hard to tell). Unfortunately - doing this comes at a cost of a little top end air and balance with the mids & bass. I need to do more listening to confirm whether this is a good long term option. I suppose it is all about compromise - have sibilance on some recordings and acceptable on others, or acceptable on sibilant recordings and dull on others..

    3. Forwardness / brightness - I still feel there is some forwardness in the 4 - 6KHz area. I find the speakers a little too bright on some recordings, especially at volumes I know the AMP can drive (from other speakers with same sensitivity). I think I'm going to have to learn to measure (which I want to do to increase my skills / knowledge) to try and help me work out where in the frequency spectrum. Of course adding a 2 Ohm resistor to the tweeter circuit might have moved the xover point (and phasing?) so I could have helped one aspect and hurt another?

    I still think for the money these speakers are great. I'm just trying to extend my knowledge and use them as a learning ground and squeeze every possible inch out of them.

    Thanks,
    David.
  • 01-20-2005, 03:54 PM
    dave_bullet
    Freeshipping - if you want me to post a photo of the extra resistor if it helps you understand where to put it - let me know.

    Cheers,
    Dave.
  • 01-20-2005, 03:56 PM
    Free USA Shipping
    Right, changing the internal volume is not a good idea. However, I doubt the Madisound foam is effectively decreasing the internal volume. I'm guessing it's just not the right stuff for the job, however apparently Madisound must not think so. I already had ordered some acousta-stuff from PE so I will use it when it arrives early next week. I never thought to use poly-fill from Wal-Mart. I still would like to find out how to do the mod with the resistor, hopefully by next week. Thanks
  • 01-20-2005, 04:00 PM
    dave_bullet
    G'day there Free USA Shipping,

    I'll post a photo of where to put the extra resistor tonight and what the circuit changes to.

    I'd recommend you try adding on a 4 ohm resistor to the end of the existing 2 ohm one (you'll see what I mean when I post the photo). The reason to do such a big jump first is you can easily here the difference from the standard xover to see if you think it is too much of a treble cut or too little. I found each increase of 1 ohm only changes the sound by about 0.5 - 1dB (hardly noticeable). So I'd recommend you use the 4 ohm resistors (to give you a total of 5 ohm and 6 ohms per speaker)

    David.
  • 01-21-2005, 02:45 AM
    Free USA Shipping
    Quote:

    Originally Posted by dave_bullet
    G'day there Free USA Shipping,

    I'll post a photo of where to put the extra resistor tonight and what the circuit changes to.

    I'd recommend you try adding on a 4 ohm resistor to the end of the existing 2 ohm one (you'll see what I mean when I post the photo). The reason to do such a big jump first is you can easily here the difference from the standard xover to see if you think it is too much of a treble cut or too little. I found each increase of 1 ohm only changes the sound by about 0.5 - 1dB (hardly noticeable). So I'd recommend you use the 4 ohm resistors (to give you a total of 5 ohm and 6 ohms per speaker)

    David.

    Yes, a photo likely would help. At this point I plan on adding a 5 ohm resistor for each speaker instead of a 3 or 4 ohm. So I take it I will need to solder each end of a 5 ohm resistor to separate points somewhere on one crossover and then repeat for the other crossover. Is this correct? Thanks
  • 01-21-2005, 07:04 AM
    tillerman
    Homework
    Free Shipping,
    You need to go to Forums Links(bottom left of tweak,mods DIY page) Click old forums - Click tweaks mods,DIY. This will take you back to much more build info. on Eds' speakers back to 2002.
    You do Not want to be soldering resistors on to your crossovers!!!!!! The resistor tweaking is done with quick connects on the wire between the crossover and tweeter. Dig and ye shall find.
    If you are new to room acoustics, speaker placement,etc. I suggest you spend a fair amount of time researching for your specific listening area!
    Once you've got your speakers in the right place, at the right height, solidly set on good stands with halfway decent speaker wire; then do your final tweaking. Good Luck!
  • 01-21-2005, 07:17 AM
    Free USA Shipping
    Quote:

    Originally Posted by tillerman
    Free Shipping,
    You need to go to Forums Links(bottom left of tweak,mods DIY page) Click old forums - Click tweaks mods,DIY. This will take you back to much more build info. on Eds' speakers back to 2002.
    You do Not want to be soldering resistors on to your crossovers!!!!!! The resistor tweaking is done with quick connects on the wire between the crossover and tweeter. Dig and ye shall find.
    If you are new to room acoustics, speaker placement,etc. I suggest you spend a fair amount of time researching for your specific listening area!
    Once you've got your speakers in the right place, at the right height, solidly set on good stands with halfway decent speaker wire; then do your final tweaking. Good Luck!

    Okay, I shall research. But before I do, what is a "quick connect"? Is this an alligator clip? Thanks for the good advise.
  • 01-21-2005, 07:36 AM
    kexodusc
    FreeUSAShipping: No, not decreasing the internal volume INCREASING, this is worse than decreasing for the midrange, IMO, and probably makes the bass a bit boomy. Dampening material "tricks" the vibrating air in the cabinet into acting as thought the cabinet has been increased in volume by lowering the Q factor ( measurement of the storage and release of energy - low Q = faster release...improved transient response) ..but too much is bad...with the Madisound foam, lining the rear wall would have been more than sufficient, but I still think polyfill is your best option...

    Madisound sends the foam because with most ported speaker systems, generally (there's exceptions of course), foam is used is used to line the walls...affecting Q...but some designers already have Q in mind when designing cabinet size, drivers, etc, and you'll find the odd ported design that works better with stuffing material. Ed has stated several times the polyfill is an integral part of the design.

    I'm not sure the foam would kill the bass response though, but it might. This is why I was worried about the comment you make about wanting to "add to the bass" and why I questioned if you had wired everything properly, lack of bass is often the side-effect of reversing the polarity.

    Hopefully everything works out. Let us know what you think of the resistor tweaks.

    Good luck.
  • 01-21-2005, 12:03 PM
    Free USA Shipping
    kexodusc,
    I'm not sure I mispoke when I said, "I doubt the Madisound foam is effectively decreasing the internal volume." Are you saying the addition of the Madisound foam may have effectively increased the internal volume? If so, this seems counter-intuitive. Of course I'm not that experienced with all of this.

    For now I'm hoping the acousta-stuff from PE will add a bit to the bass and clear up the mids. And I'm hoping the addition of a 5 ohm resistor to each speaker will tame the tweeter a bit and correct the sibilance.

    Before attempting these mods, I will be working a bit more this weekend on room acoustics and positioning the speakers on more solid stands. Who knows, I may see some improvements.
  • 01-21-2005, 02:52 PM
    dave_bullet
    2 Attachment(s)
    Quote:

    Originally Posted by Free USA Shipping
    And I'm hoping the addition of a 5 ohm resistor to each speaker will tame the tweeter a bit and correct the sibilance.

    Freeshipping - I've attached a photo showing how I attached the resistor (madisound supplied PCB & xover). Note I've soldered it. I'm happy with this as I am comfortable unsoldering if needed - but I prefer the AR.coms with this setup. I recommend as others have to use aligator clips (as long as they securely attach! - don't want a short blowing your output stage on your amp!) Atleast with soldering - you "know" no stray wires will come loose when you put the xover back into the cabinet. To me it is more important to protect my amp.

    anyway... My xover as shown has the 5 ohm resistor (at the back covered by some polyfill). I unsoldered the 2 ohm resistor and added another one to the end (as shown) then re-attached the new resistor to where the old 2 ohm resistor terminated (at the bottom) - you can see the tweeter +ve wire also (I've marked it all so it will be pretty straight forward.

    If you do not want to unsolder the original 2 ohm resistor on the madisound board - you could simply put the resistor on the wire between the board and tweeter itself - which is what the others and Ed originally recommend. I just have a personal preference to solder and put xover components on the board.

    David.
  • 01-21-2005, 03:01 PM
    dave_bullet
    3 Attachment(s)
    I've attached 3 images showing the simulated response by using 2 ohms (standard), 4 ohms and 6 ohms to pad the tweeter - so you can see how it shapes the treble response.

    As you can see, an increase in 2 ohms = about a 1dB cut. the hump from 2.7 - 4.5KHz is caused by the breakup mode of the woofer.

    David.
  • 01-21-2005, 05:36 PM
    kexodusc
    Free USA Shipping: It is counter-intuitive, and I'll have to consult a few books for a thorough reason why, but basically I believe the way the air vibrates, and the energy inside a dampened cabinet create the effect of a increased "virtual volume" if you will. Dampening material definitely gives this effect...I'll get back to you with more accurate reason as to why.
  • 01-22-2005, 03:10 AM
    Free USA Shipping
    Quote:

    Originally Posted by kexodusc
    Free USA Shipping: It is counter-intuitive, and I'll have to consult a few books for a thorough reason why, but basically I believe the way the air vibrates, and the energy inside a dampened cabinet create the effect of a increased "virtual volume" if you will. Dampening material definitely gives this effect...I'll get back to you with more accurate reason as to why.

    That's okay, I'm not after a textbook explanation and consider myself enlightened with your current explanation. Thanks
  • 01-22-2005, 03:22 AM
    Free USA Shipping
    Quote:

    Originally Posted by dave_bullet
    I've attached 3 images showing the simulated response by using 2 ohms (standard), 4 ohms and 6 ohms to pad the tweeter - so you can see how it shapes the treble response.

    As you can see, an increase in 2 ohms = about a 1dB cut. the hump from 2.7 - 4.5KHz is caused by the breakup mode of the woofer.

    David.

    Thanks for the graphs. So the 2 ohm graph is of the crossover without the addition of any other resistors? And, the 4 ohm graph shows the results when a 2 ohm resistor is added to the existing 2 ohm resistor on the crossover board?
  • 01-22-2005, 04:23 AM
    Free USA Shipping
    Quote:

    Originally Posted by dave_bullet
    If you do not want to unsolder the original 2 ohm resistor on the madisound board - you could simply put the resistor on the wire between the board and tweeter itself - which is what the others and Ed originally recommend. I just have a personal preference to solder and put xover components on the board.

    David, thanks for the photos and explanation, big help. I too would prefer to solder the resistors to the crossovers, however I have no interest in learning how to desolder so I will be using alligator clips. I see from your photo the alligator clip attaches to the speaker wire that runs from the tweeter to the positive tweeter terninal on the crossover. So, I will attach the alligator clip to either end of this wire where it has been striped bare.

    How do I attach the resistor to the alligator clip? Do I just fold the 2 wires from the ends of the resistor together and put them inside the end of the alligator clip?

    Also, from your photo I see you added a 2 ohm resistor to the existing 2 ohm resistor on the crossover board for a total of 4 ohms. So would this total of 4 ohms produce the results showing in your graph for 4 ohms, or would it be graphed as 2 ohms since you added a 2 ohm resistor? Thanks
  • 01-22-2005, 01:29 PM
    dave_bullet
    Quote:

    Originally Posted by Free USA Shipping
    David, thanks for the photos and explanation, big help. I too would prefer to solder the resistors to the crossovers, however I have no interest in learning how to desolder so I will be using alligator clips. I see from your photo the alligator clip attaches to the speaker wire that runs from the tweeter to the positive tweeter terninal on the crossover. So, I will attach the alligator clip to either end of this wire where it has been striped bare.

    You are correct

    [QUOTE=How do I attach the resistor to the alligator clip? Do I just fold the 2 wires from the ends of the resistor together and put them inside the end of the alligator clip?[/QUOTE]
    If it were me, I'd do the following

    PCB tweeter +ve terminal <-> solder a length of wire and crimp an alligator clip <-> teeth of clip onto resistor <-> resistor <-> teeth of second clip and crimp on some wire <-> solder wire to +ve terminal of tweeter

    That way - you have an alligator clip off the PCB and one off the tweeter - so you can replace components in between without any soldering. If you want to remove the extra resistor - just get the alligator clips to bite onto eachother

    [QUOTE=Also, from your photo I see you added a 2 ohm resistor to the existing 2 ohm resistor on the crossover board for a total of 4 ohms. So would this total of 4 ohms produce the results showing in your graph for 4 ohms, or would it be graphed as 2 ohms since you added a 2 ohm resistor? Thanks[/QUOTE]
    Your first point is correct. The total is 4 ohms on the board so that relates to the 4 ohm graph. The 2 ohm graph is the standard board shipped by madisound with only one 2 ohm resistor.

    Let me know how you go...
    Cheers,
    Dave.
  • 01-22-2005, 01:31 PM
    dave_bullet
    Sorry - I stuffed up the quoting of your questions. You'll need to read my response in the quoted section above

    Cheers,
    Dave.
  • 01-27-2005, 12:02 PM
    Free USA Shipping
    dave_bullet,

    I'd like to wire the resistor as you suggested in the following. Would I do this in place of the existing wire between the PCB tweeter + terminal and the tweeter's terminal, or are you suggesting I do this in addition to the existing wire that runs between these two points? Thanks

    "PCB tweeter +ve terminal <-> solder a length of wire and crimp an alligator clip <-> teeth of clip onto resistor <-> resistor <-> teeth of second clip and crimp on some wire <-> solder wire to +ve terminal of tweeter"
  • 01-27-2005, 11:19 PM
    dave_bullet
    If you have one piece of wire already between the PCB +ve and Tweeter +ve, then you just use that - but unsolder (or unclip - however you've attached it) at one end. This becomes *EITHER* the PCB end of wire *OR* tweeter end of wire in my

    "PCB tweeter +ve terminal <-> solder a length of wire and crimp an alligator clip <-> teeth of clip onto resistor <-> resistor <-> teeth of second clip and crimp on some wire <-> solder wire to +ve terminal of tweeter"

    explanation as underlined above.

    I hope that helps

    Cheers,
    DAvid.