orig. SVS drivers for a DIY sub?

Discussion in 'Archived Threads 2001-2004' started by Tom Wyatt, Feb 12, 2003.

  1. Tom Wyatt

    Tom Wyatt Extra

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    Hey guys, been hanging around a little here, and I am working my way up to finally building a DIY sub (or 2) I think. Problem is, everytime I think I've made my mind up to do something, I re-think the whole thing. Here's my current subwoofer set-up...

    I have 1 Sony SA-WM40 corner loaded. I get pretty flat response considering it's a $150 sub, down to around 35 Hz. After that, it falls off quickly. The big problem I'm facing is too little bass. I really like bass, and this doesn't do it for me. I watch a lot of (primarily action) movies, and play a little classic rock, jazz, or classical. Ratio is probably 85% movies, 15% music.

    My listening / HT room is 34' long, 17' wide, with a vaulted ceiling, measuring 25' at the peak... so, it's a BIG ROOM TO FILL. Further, it opens to the loft on the rear left-hand (facing the TV) upper wall, and into the kitchen just below that... The TV is on the right-front corner, and the front door is on the front-left corner. The sofa is in the center of the room. Right and left surrounds are approximately centered in the room, and rear center surround is on the back wall (34' from tv).

    OK, now for the questions. That little Sony just doesn't cut it. It bottoms out or clips (not sure which) whenever I get close to reference levels in movies. All speakers are set up using the radio shack meter (corrected for the RS spl meter's inaccuracies) I need a serious sub(s). So, I began to look at what was available. Within my spending limits (wife-imposed), I figure I could probably get one SVS powered sub, or build a couple of good DIY subs.

    I was originally planning on building 2 shiva-based subs, but I just found a contact with 2 original SVS subs for sale. How would these compare, and what power requirements would these have compared with the Shiva. I'd ideally like to run these off my old Technics receiver, rated at 150 x 2 @ 4 ohms. (if this is unrealistic, please let me know)

    Finally, being new to the DIY arena, and still having only a simple understanding of the physics involved, what type of enclosure should I look to? I'd probably either (1) have these subs aligned both in the front-right corner, approximately 2' behind the RPTV, or (2) aligned on either side of the couch, depending on the enclosure size, of course.

    I'm assuming that a ported enclosure would be best with either of these subs, as my bass requirements are high, but would a "cube" design work well?

    Thanks for any and all input.
     
  2. ColinM

    ColinM Cinematographer

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    I went through this 3 months ago - All replies pointed out that the Shiva and SVS are "close enough" in TS specs to be used interchangeably.

    That said, I used 1 SVS original in a ported 88L box, 8-3/4" long center tube 3" port kit. Later I added a bit of fill to see what would happen, no big woop. (Adire's plans)

    The sub performs great for me, in a 28' x 13' x 8' room with 2 open doorways feeding another 500 sq ft. I can get 95db peaks from the whole system before my receiver clips my mains. The sub is EQ'd by a 31 band and is very flat, and works well to 22hz.

    If I had 2, I'd build a single enclosure, front firing and sealed, stuffed, and about 4 cu ft. just for fun.
     
  3. Geoff L

    Geoff L Screenwriter

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    Being that you made it clear your a bass head and the little Sony just isn't cutting it, I would go EBS ported.

    I would consider building 2 clones of the 2039 SVS. They don't have to be tubes, you could go the box route also. You just need to maintain the internal cabinet volume that the 2039 has, and tune to 20 hz. The only concern is, if your going to drive them with the Technics receiver, (a subsonic filter) might be a good idea to protect them from premature bottoming and wasting the Techncis headroom below tuning.
    You have a very large area to fill and this approach would most likely get you the most for the least dollar $$$$ output.

    A single box cabinet with both drives also could be used (ported), but the size could get rather large. Sealed certainly could be done as suggested above, but given the power your working with and the area you trying to fill, most likely not the best approach when looking for extension and output in a reasonable box or tube size.

    There are many different options obviously as far as other types of alignements you could choose from.

    I have 4 SVS original drivers, 3 of which are sealed and ~{1 is a clone of the SVS-2039 tube style}~. For shear output, extension, & impact per given watt, the 2039 clone kicks it with movies and dose music very nice. It is being driven with the PE-250-watt plate amp.

    It all depends on your needs/prioritys and budget. If thats what you intend on driving them with (the Technics) and (spl) along with extension is high on the list, this is what I would look to.

    Clone whats proven to work...[​IMG]

    Just a thought:::>
    If your not comfortable with wood working, you might consider calling on Dustin or Kyle to build your final deceided design. Very reasonable pricing for the fantastic work they do. Could build your cabinet/s or tube's and all you have to do it bolt your driver in.
    A small price to pay for the beautiful work they do....

    Regards
    Geoff
     
  4. Allen Ross

    Allen Ross Supporting Actor

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    is that technics rated for a 4 ohm load? to my knowledge, many home recivers arn't designed for a 4 ohm load
     
  5. Tom Wyatt

    Tom Wyatt Extra

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    Thank you all for your responses thus far. They've been very helpful. Ideas are running through my mind.

    To answer your question, the Technics is "officialy" rated for 4 ohm load (as per the manual), on the front channels. It is a 5 x 100 amp (supposedly) at 8ohm, model SA-AX540. It was my old HT receiver, until I got the Pioneer VSX-D811S.

    I thought that I'd be better off with a ported design, because of my power limitation, and was thinking of setting each sub up in a short (~25") square / rectangular box, downfiring, on either side of the couch (sort of an end-table type thing. I thought this may take away some possible detrimental effects of running 2 big subs directly behind a RPTV, (as in possible rattling of things that should not be rattled inside the TV). Is this concern a well-founded one, or should I place the subs behind there and not worry about it?

    Also, does anyone know the internal volume of the 20-39's box?

    THANKS!
     
  6. Geoff L

    Geoff L Screenwriter

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    Hi Tom

    I have my 2039 clone behind my RPT and to this point no problems aside from the screen flexing when really pumping the spls..

    But 2 of them and playing very loud might not be a great idea. My sub is corner loaded and the sub is 1 inch from touching the Sony RPTV.
    Love that free room gain!

    Ok found my old notes and the internal volume is ~{this taken from a friends original SVS-2039PC}~ Did the best I could at measuring the dimension with out taking it apart. He said NO WAY, don't think so bud.

    The internal volume of the REAL SVS-2039 self powered, is about 3.80-cf^3.
    Edit:
    "Assuming I did the math right", aproxment internal dimensions of the REAL powered SVS-2039 tube are 15.5" x 34.5" give or take and 1/8 of an inch...
    I used a 16" piece of sono tube 36" long in my clone. 3/4" mdf inside both the top and bottom.
    End Edit:

    This dose take into account the clones SVS driver, PE-amp, and flared on both ends, 4"x 17.25" PP port volume. Tuning is just a little over 20-hz.
    (If the port is not flaired on both ends it needs to be longer, about 19")
    My amp is also flush mounted into the sub. Driver is in the bottom with a base plate and ported out the top. Basicly it looks just like a SVS 2039pc.
    Egg crate foam 1-1/2 thick from Parts Express lines the inside wall.

    Obviously it's a tube sub.

    Regards
    Geoff
     
  7. Tom Wyatt

    Tom Wyatt Extra

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    Thanks to all for all the help. After spending a great deal of time this week working with modeling spreadsheets in Excel, I decided to go for around 4 Cu.Ft. I then went over to Home Depot last night, and got home and started cutting... I just put the last side on the box this morning (ok, so things go slowly when you are doing all the cuts with a jig saw). It's 20 (H) x 22 x 22, all MDF. Both the woofer and port will be downfiring. I plan to put 4" legs on it, paint it to match our current coffee table, put a nice wood top on it, and use it as a (rather large) end table, between a wall and a couch (approx 12" from the wall). I heavily braced it, and comes out to a net internal volume of about 4.08 Cu. Ft., considering everything (I even took into account the volume of the binding posts and 12 awg speaker wire LOL).

    I put a 17" long, 4" PVC port in, to tune it between 20 and 21 Hz. I know 20 Hz or lower would be better, but I ran out of room to route the PVC... and didn't want to put a turn in it (bracing didn't allow much manuvering room). I figure that the 1 lb of polyfill probably will help a little. It's drying as I write this (while I'm at work).

    I don't have the SVS speaker yet, but I do have an old Kicker Solobaric that I'm going to run in it until I decide to get a better speaker. This way, I figure I'll be more happily surprised to hear how good it sounds once I make that jump. It should sound pretty good in this box.

    Anyway, I just wanted to jump back on here and fill everyone in on how things were going. [​IMG] I'll most likely do some freqency and SPL tests some time this weekend, if all goes well. (can you tell by my excitement level that this is my first DIY?)
     
  8. Geoff L

    Geoff L Screenwriter

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    Tom

    Where did you go!

    How did your testing go and did your SVS driver show yet? [​IMG] [​IMG]

    Also if you spring for a PP 4" flared port from PE you could drop the tuning a little. They are 17" long and because of the flares at both ends, it equals a 19" straight 4" pvc tube port. Might get you a db or so more output, and would certainly help with port noise just below tuning.

    So whats the latest on you project/s and testing with either driver.

    A SVS-1646 total internal volume is aprox 4.40-ft^3 if you may be curious.

    Geoff
     
  9. Tom Wyatt

    Tom Wyatt Extra

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    Sorry, been kind of busy lately. My wife decided that since I got to kick up all kinds of dust in the garage, she'd paint a room! so, our laundry room is now red, and since I got to "help out" (finish the job she started, LOL) I have been one tired puppy.

    At any rate, still using the Kicker (I have a line on a SVS driver, but hadn't made the decision to buy it yet). I first wanted to see how the enclosure building would go, and if it went well (which I think it did), then look to get a better driver.

    I have the sub placed between the couch and the center of the 34' long wall, 6" away from each. It's a downfiring configuration, as I said, and overall I'm pretty happy with the results. There are some definite room issues that need to be resolved because of the size and shape of the room. The resolution will most likely come through an equalizer, but that certainly won't happen until I get a better driver. Overall, the Kicker packs a "punch", but isn't that musical... still, it's better than solely the Sony.

    I will definitely look into the flared-end port, that may be my ticket to a 18-19 Hz tune... I'd like to get everything out of this that I can.

    I put up a Yahoo photos page with a few pictures, both of the sub itself and of the testing output. enjoy, and tell me what you think. HERE'S THE LINK

    EDIT: I should note that the spl levels listed in the picture of my frequency response are from the main listening area... approximately 6' from the sub.

    Thanks
    Tom
     
  10. Geoff L

    Geoff L Screenwriter

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    Tom

    What the Receiver crossover set at thats feeding the Technics sub amp?

    Did you have all the other speakers "off" when running your test for the graph?

    What did you use to test the sub and graph it?

    Could you post the TS params of the Kicker driver?

    Is the Kicker a dual voice coil unit and if so are you running both channels of the Technics to it?

    Is that paint on the sides or primer, and have you considered a bass plate out of the same thing the top is made of?

    And lastly is there anyway to corner load the sub in your room for a comparison freq graph?

    Sorry for all the questions but curious minds want to know...

    Regards
    Geoff
     
  11. Tom Wyatt

    Tom Wyatt Extra

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    happy to see you're still up.

    1. I ran the "NCH tone generator" for the test tones on my laptop, through an RCA jack into the amp. Therefore, there was no crossover in the equation. I know that this isn't exactly how it will perform when driven by the signal coming from my other receiver, but I figure it's close, as the crossover on my Pioneer (main reciever) is set to low pass at 100 Hz.

    2. As I said above, only the sub amp was on, and this was the only sub running at the time (sony wasn't running).

    3. TS params: (via WinISD)
    Qts .32
    Qms 9.34
    Qes .34
    SPL 88.28 dB
    Vas 212.3
    Fs 18.57 Hz
    Xmax 8.5 mm

    It's a single voicecoil, 4 Ohm driver - running only the Left channel of the Technics to it (nothing else running on that receiver). It is one of the original solobarics the S12C4, before they were sqauare...

    That is a pale cream paint on the sides, matching the coffee table that isn't pictured.

    I thought about at baseplate, but honestly wasn't sure how to attach it or if it would look right... unfortunately aesthetics is pretty important here

    I will attempt to corner load it sometime this week (earliest will be tomorrow afternoon) and post my results on this thread.

    EDIT: for the graph, I just entered the numbers into Excel and ran a line graph.. nothing fancy
     
  12. Pete Mazz

    Pete Mazz Supporting Actor

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  13. ColinM

    ColinM Cinematographer

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    On Adire's site, in the plans for the subs, it says to add 5" if you use a straight pipe vs. flared.

    They say 8.375" flared 3" fo my plan, so a straight would have to be 13.375".

    FWIW, I really like the SVS driver in the ~88L box I made. I'll do it again but this time I'll pay more attention to the cosmetics. EQ'd I can get fantastic performance to 22Hz. I kill anything below that to preserve headroom. I think...
     
  14. Tom Wyatt

    Tom Wyatt Extra

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    wow, 5"... that's a big difference. That's the difference between 21 Hz and 19 Hz tune in my box...
     
  15. Geoff L

    Geoff L Screenwriter

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    My apoligizes....

    The center section should be cut 5" shorter than the LV=length of the needed port.

    When assembled, (attaching the flared ends to the center tube section) the port should be 1" longer than the needed LV.

    Taken from PP instruction page. Look here
     
  16. ColinM

    ColinM Cinematographer

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    Yep - that goes along with the Adire instruction - Adire's instruction to make the port 8.375 is for the center tube, then attach the flares.

    Makes sense.

    Hey - we figured something out!
     
  17. Tom Wyatt

    Tom Wyatt Extra

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    OK, Geoff and others:

    I did the corner-loaded frequency test. I posted the pictures back on THIS PAGE

    As you'll see, it raised my response in the 20-40 Hz range pretty well. Additionally, you'll see that the big response down REALLY low (sub 18Hz) is gone. I got to thinking the other night that this most likely was just cone "flapping" and not really true sub response. So, I lowered the sub amp volume down to just 3/4, and tried it again. The SPL response was much lower relative to that at around 30 Hz, but I actually felt the floor (and windows and walls and fireplace) shaking. So, this is now true response, and not just "flapping". I re-ran both sets of tests today, first at its current (side wall) location, and then in the corner, both at 3/4 volume on the sub amp.

    Additionally, you'll see the large room peak at around 45 Hz, I can only attribute this to the room itself, as I saw this in my sony, as well as with this new sub.

    Anyway, hopefully I've answered your questions, and you'll post your thoughts...

    Tom
     
  18. Geoff L

    Geoff L Screenwriter

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    Hi Tom

    Well guess we will wait for your SVS to come but I think a BFD is in your future. thats a nasty room peek with a pretty wide spread you have their.

    Even a standard 12 band would help as the peek is wide enough that it might be useful.
    The BFD is the way to go, but if you have an eq laying around it might be worth playing with.

    A subsonic filter would be a good idea also below tuning.

    Edit:
    On the For Sale page someone has/had a ART up for sale very cheap last time I was over their. Might be worth checking into....

    Regards
    Geoff
     

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