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The PEDS - a 2.1 speaker system for your desk, den, bedroom or office

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  • BOBinGA
    replied
    Sorry, but I never posted it. I will try to get to it sometime this week.

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  • Kootskid
    replied
    Hi Bob,
    Would you be able to post the build of your mtm center channel you use with the peds. Thanks for the help.

    Myles

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  • BOBinGA
    replied
    I cannot say how it handles over driving. I have never driven it to shutdown. I have only played it comfortably loud.
    -Bob

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  • Scarface1
    replied
    Hi Bob, the nd-105 don't like a enclosure under 2 liter( as you say).Lets say the nd-91 do it a bit better and a little bit smaller.

    the nd-105 in 2 liter(green) and the nd-91 in 1.5 liter(red)
    ​​​​​​
    I have a little bump at 100 hz to compensate the cross over roll of that is build in de dayton amp. If I use the nd-91 I really like to built the heliums.

    also is the dayton amp a bit " user friendly " , so easy to work with. Like over protection if I set it to loud.

    thanks

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  • BOBinGA
    replied
    The ND105s should work well with that amp and it's crossover. I considered their little brother ND90 for my build, but in the end, the DS90 was a better fit for the tiny Denovo cabinets. The ND105s will require a slightly larger box, but that's easy enough to do.
    -Bob

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  • Scarface1
    replied
    Sorry bob, after reading a little furder I found the result of the test. I want to buy this amp and use it with the W6-1139SIF and maybe the dayton nd-105.

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  • Scarface1
    replied
    Originally posted by BOBinGA View Post
    Re: The PEDS - a 2.1 speaker system for your desk, den, bedroom or office

    Sorry about that. It is confusing. No, there is no separate LP filter on the sub now. I did the XO diagram based on my initial tests where I used a LP filter on the sub and ran everything from one amp. Once I added the plate amp, I eliminated the LP filter on the sub. The sub is wired directly to the plate amp and uses its built in LP filter. The satellites are run separately from the speaker terminals on the plate amp as you would expect. Its hard to read in the picture, but I drew a box around the LP filter for the sub and put in a note saying that is was not needed when the amp was used. So disregard the LP filter on the sub section.

    A quick note on the plate amp. From what I could tell, the bass boost circuit is actually a 6db boost at 40hz. The spec say 3db at 63hz. The actual filter does boost 63hz by 3db, but is also boosts 40hz by 6db, so the spec are, I guess, correct, but a bit misleading. You can model the woofer in WinISD using the "peaking 2nd order high pass" using 6db at 40hz and it matches the measured response exactly. You can also turn off the bass boost and measure and, sure enough, the output in the low 40hz range is indeed 6db lower than with the boost enabled. Also, the specs on the plate amp say it has a built in HP filter set to 150hz. But from what I can tell, it looks more like an 80hz HP. I haven't looked closely at that part yet, but if so, this is good.

    -Bob
    Hi Bob, nice work! After reading that the high pass is at 80 hz I want to buy this amp but only if it's 80 to 100 hz highpass because I don't want my sub play higher than 80 hz

    greetings

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  • Kootskid
    replied
    Bob,

    Thanks a lot. I would be interested in your equipment that you use for measurements. I am in the market to buy some equipment, but not sure what to buy as I am just a hobbyist having some fun. Would still like some quality measurement gear to get going. Would be nice to have a new post for reference. Thanks again

    Myles

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  • BOBinGA
    replied
    Hi Myles.

    I actually measure everything first. I measure T/S parameters, response in room with a calibrated mic and in the box I intend to use and base my XO based on those measurements. For the most part, in my experience PE's T/S parameters are good, but unless you measure in box and in room, you cannot easily predict the baffle step you need to account for in your XO.

    I also have a mtm horizontal center channel with the DS90 and ND16 built and in use for the past year. I am on vacation with only my tablet and don't have the design at hand, so I will have to ask for a few days until I can post the design next week some time. I do remember that I had to design a couple of dB hot in the 2k to 4k octave so that it sounded more natural 15 to 30 degrees off axis where my wife and I sit in the living room. These are the kind of things that just using the measured parameters can't tell you.

    Give me a few days to get back home and look up everything on my home laptop. I will post the design and a short write up of my reasoning.

    -Bob

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  • Kootskid
    replied
    Hi Bob,

    I am thinking of building the PEDS as I have previously bought some DS90's and some ND20FA tweeters. I would not build the sub as I have one already. I would like to build a center channel using the DS90 and the ND20FA in an horizontal mtm configuration. Would you have any idea's on why this may not work?. If no negatives, I will start playing with some free design software. Did you measure the T/S parameters of the DS90 or just used the published data on the PE site. Thanks for the help, I tried to PM you, but was not allowed for some reason. I am investigating with the Web Manager.

    Myles

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  • donradick
    replied
    I'd forgotten that you used the DS90s - they sounded great.
    I'm finding ported subs not to my liking, and coming around to your preference of sealed subs.

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  • BOBinGA
    replied
    I can't believe its been three years since I posted this little project. My set of PEDS have been doing a great job as the mains for my modest living room TV.

    ​I had a request to see what changes might be needed if the newest version of the DS90 were used in place of the old ones the PEDS were built from. I swapped the old and new DS90s into my PEDS without any changes to the crossover and the difference is so slight, I wouldn't change anything. If I were to change anything, I might try a 4 ohm resistor for R2 in front of the tweeter instead of a 5 ohm resistor. This is measured with my mic compensation inadvertently turned off and in a different position and location than the measurements in my PEDS description, so its not quite as bright on the very top end, but it still shows a very flat response using either woofer +/- 2db from 150 to 20,000 hz other than that one small dip at 16,000 which you are not likely to hear. But that is just a property of the ND16 tweeter. I also have newer versions of the ND16 tweeters and those are identical to the ones I used originally.
    Attached Files
    Last edited by BOBinGA; 06-26-2017, 04:26 PM.

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  • joeybutts
    replied
    Re: The PEDS - a 2.1 speaker system for your desk, den, bedroom or office

    Hi Bob! Quick question which I don't believe I read in the thread, do you happen to know the F3 of the satellites? Got a buddy looking for a pair of speakers for his film history class and looking to keep it budget friendly. He can't utilize a lot of bass due to poor room construction and flanking, but I think if I can get him something respectable around 80hz that would be good. I've looked at a few designs and figured this may be another option for him.

    Thanks!

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  • BOBinGA
    replied
    Re: The PEDS - a 2.1 speaker system for your desk, den, bedroom or office

    Thanks everyone for your interest in my little project.

    One recent question asked about using the PEDS without the feet, so I took another look at that. Here is a response chart with the mic on axis with the speaker tilted and then again with the feet hanging over the front edge of their stands so that I was measuring perpendicular to the face. (The design axis is half way between the center of the two speakers. Also, since there is no degree symbol on my keyboard, I will use a * instead.)



    You can see that it really makes little difference. Yes, if you tilt them back and listen directly on axis, you get a very flat response. That's the darker line in this graph. But if you eliminate the feet, you still get an easily acceptable response shown by the red line. Using them without feet does cause a small peak around 1500 hz leading down to a dip around 9k, but it only 3db and still quite acceptable. (I should note here that I used one octave smoothing for the graphs in this post to more easily show the differences. Had I left the smoothing at 1/6 octave, it would have been very difficult to show any changes.)

    While I had the mic set up, I also measured the polar responses. First, here are the horizontal changes with listening angle:



    Its not Geddes perfect out to 60*, but its within a 5 db window from 40hz to 10K hz, which is still pretty darn good. If you stay within 45* it even stays in a 3db window. You can see that by 3K, the woofer is starting to beam a little bit but the tweeter starts to take over by 5K and you are back to normal response levels.

    The vertical polars are not as pretty, but they are still very good within a 15* window.



    These are measured perpendicular to the face of the speaker - not with them tilted back. So I included a measurement at -11.8* (the red line) that corresponds to the tilted position using the feet. But the big point here is that the response gets quickly out of whack if you go above the box. Even at 15* above perpendicular, it starts losing treble. But even out to 20* below axis, you still get very good response. This corresponds to lying on the floor about six feet in from of them on a three foot stand. Your kids might do that, but seated in a chair, there are no problems.

    The moral of this little story is that yes the feet help a little bit if you are right on axis. Off axis to the sides, they perform well way out to 45*. The vertical response shows that when choosing a stand or a shelf to put them on, its better to have them a little above ear height than below. Ear height with the feet is still your best bet, but don't worry if this is not possible in your room.

    Well, the honey-do list is calling, so that's all I have time for today. Next time, I will try to take them apart and show individual driver responses. But that's going to take some time, so I won't be doing that this weekend.

    Oh, one last thing. I set all the sub and satellite knobs on the amp to 1 o'clock as a starting point. You can adjust to taste from there, but most of the measurements above were with them set that way.

    -Bob
    Last edited by BOBinGA; 09-04-2015, 03:08 PM.

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  • chrisn
    replied
    Re: The PEDS - a 2.1 speaker system for your desk, den, bedroom or office

    Good job, they look nice!

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