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  • ontariomaximus
    replied
    Originally posted by Chris Roemer View Post
    I think max's 4" long 3" id port will be spot on. 20w RMS into the mid 40s b4 xmax, F3 below 50, about 50 fps maxed out.
    I've got 2 datasets for the 830656 SDS (PE# 264-1078); an older set,
    and this one from 2015:

    Click image for larger version

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    THANKS - I just confirmed in WINISD and will go with 34litre tuned to 49hz (3" x 4.38" port)

    Leave a comment:


  • Chris Roemer
    replied
    I think max's 4" long 3" id port will be spot on. 20w RMS into the mid 40s b4 xmax, F3 below 50, about 50 fps maxed out.
    I've got 2 datasets for the 830656 SDS (PE# 264-1078); an older set,
    and this one from 2015:

    Click image for larger version

Name:	830656pair.jpg
Views:	51
Size:	116.5 KB
ID:	1447166

    Leave a comment:


  • tvrgeek
    replied
    Originally posted by ontariomaximus View Post
    If someone could double check my simple calculation.
    A 34 litre box could be tuned to 50hz with a 3" round port 4.16" long?
    Did you download WinIsd? If doing all the work to build a box, please put some effort into the advice you are given. WinIsd will check the port Mach number for you.

    Leave a comment:


  • Geoff Millar
    replied
    Originally posted by a4eaudio View Post

    Definitely agree on measurement, lots of measurements are significantly different than manufacturers specs. On the other hand, trash the charts because the software is so good IF you give it good inputs.
    My T/S parameters for the WinISD sim above is based on the average of measurement for 4 drivers, except VAS which I used mfg specs. (I didn't even realize I wasn't using mfg specs until your post and I went to check. I must have measured these awhile ago because I didn't even remember that I had.)

    My measurements are below.

    Click image for larger version

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    Thanks for those measurements: some are about 10% out, which would make a difference when modelling.

    I've used the 830656 in two projects - a TM with the BC25TG and Ron's C Notes - and really like it, especially because you don't have to countersink it! Makes for less dust and swear word output.

    Geoff

    Leave a comment:


  • Chris Roemer
    replied
    Baby Driver

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  • a4eaudio
    replied
    Knowing that the woofer was the Iron Driver back when the Saffron won and the Ron E.'s C-Notes were widely praised I tried to keep a record of what everyone did. I figure I trust a bunch of people actually listening to speakers built by people who know what they are doing than just simulating in WinISD. I'm still in the planning stage but my target for two drivers is 28L tuned to 44Hz although I don't remember how I came up with this.

    Edit: If you look up Ron_E's C-notes he ended up changing the tuning to 36Hz and liked it better, but I don't remember what is box volume was off hand.

    Leave a comment:


  • ontariomaximus
    replied
    Originally posted by a4eaudio View Post

    Hi Ontario. Let me begin by pointing out that you did not link to the Saffrons or specify what drivers they are. However, Geoff provided the link and I happen to be building something with these woofers.

    With two drivers in 34 L and tuned to 50Hz I get a 3" port at 4.12" long. So you seem to be spot-on.
    The transfer function I get is below.

    Click image for larger version

Name:	34L 50Hz temp.PNG
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    I think I need to lower the tuning to 40-41hz. Seems to be a pretty large bump with 50. But high qts does that.

    Leave a comment:


  • a4eaudio
    replied
    Originally posted by Regore View Post
    I physically measure all required Thiele/ Small parameters with my test equipment and signal generators. Hard to break old habits when they work just fine. Never trusted published specs.
    Definitely agree on measurement, lots of measurements are significantly different than manufacturers specs. On the other hand, trash the charts because the software is so good IF you give it good inputs.
    My T/S parameters for the WinISD sim above is based on the average of measurement for 4 drivers, except VAS which I used mfg specs. (I didn't even realize I wasn't using mfg specs until your post and I went to check. I must have measured these awhile ago because I didn't even remember that I had.)

    My measurements are below.

    Click image for larger version

Name:	830656 TS measurements.PNG
Views:	199
Size:	19.6 KB
ID:	1447135

    Leave a comment:


  • Regore
    replied
    I started designing speakers long before modeling software became available. I use the charts provided in Vance Dickason's Loudspeaker Design Cookbook. I physically measure all required Thiele/ Small parameters with my test equipment and signal generators. Hard to break old habits when they work just fine. Never trusted published specs.

    Leave a comment:


  • a4eaudio
    replied
    Originally posted by ontariomaximus View Post
    If someone could double check my simple calculation.
    A 34 litre box could be tuned to 50hz with a 3" round port 4.16" long?
    Hi Ontario. Let me begin by pointing out that you did not link to the Saffrons or specify what drivers they are. However, Geoff provided the link and I happen to be building something with these woofers.

    With two drivers in 34 L and tuned to 50Hz I get a 3" port at 4.12" long. So you seem to be spot-on.
    The transfer function I get is below.

    Click image for larger version

Name:	34L 50Hz temp.PNG
Views:	216
Size:	129.5 KB
ID:	1447131


    Leave a comment:


  • Geoff Millar
    replied
    Originally posted by ontariomaximus View Post

    I saw those years ago LOL. I have had the parts for this project kicking around for a number of years. The six drivers, all the crossovers, and a note that said 34 litres net, tuned to 49.8hz and an F3 of about 48hz (pair of 830656's). Can't even remember what I used to calculate that, and WINisd is showing me something a bit different.
    Some years ago I saw a project for a MLTL for the 830656 (single driver) which gives a stated F3 in the low 30s and not very efficient: - 84dB, so it looks like you can persuade that driver to get quite low. No idea how that could be adapted to your project, I'm afraid.

    Good luck

    Geoff

    Leave a comment:


  • ontariomaximus
    replied
    Originally posted by Geoff Millar View Post

    OK, just thought I'd ask the question.

    You could check out these cabinets; one is 34l, the other 35l ; the first has a slot port, the second a tube. Not sure if they would work for you in terms of low end output.

    http://techtalk.parts-express.com/forum/tech-talk-forum/53042-iron-driver-overall-best-sounding-speaker-design-details
    http://techtalk.parts-express.com/forum/tech-talk-forum/53050-c-note-iron-driver-build

    Geoff
    I saw those years ago LOL. I have had the parts for this project kicking around for a number of years. The six drivers, all the crossovers, and a note that said 34 litres net, tuned to 49.8hz and an F3 of about 48hz (pair of 830656's). Can't even remember what I used to calculate that, and WINisd is showing me something a bit different.

    Leave a comment:


  • Geoff Millar
    replied
    Originally posted by ontariomaximus View Post

    I am aware how he did it, I just want to get some more output in the sub 80hz range. 34 litre boxes already assembled.
    OK, just thought I'd ask the question.

    You could check out these cabinets; one is 34l, the other 35l ; the first has a slot port, the second a tube. Not sure if they would work for you in terms of low end output.

    http://techtalk.parts-express.com/forum/tech-talk-forum/53042-iron-driver-overall-best-sounding-speaker-design-details
    http://techtalk.parts-express.com/forum/tech-talk-forum/53050-c-note-iron-driver-build

    Geoff

    Leave a comment:


  • dynamo
    replied
    Originally posted by PWR RYD View Post

    Someone tree'd grumpy Roemer with WinISD, but crop dusted him with prototype, test, measure (a great suggestion BTW)

    love the drag race reference!

    seems he was busy eating at Gapplebees!

    Leave a comment:


  • ontariomaximus
    replied
    Originally posted by Geoff Millar View Post
    Hello from Australia

    I'm not sure if putting this design in one cabinet will work: the designers' write up says: (http://projectgallery.parts-express..../the-saffrons/)

    "The low frequency woofer is allowed to dig just about as deep as it can without falling apart, and the mid-woofer is choked down on the low end by the enclosure volume" and "as long as the volumes are maintained, rectangular enclosures should be quite adequate" - I read this as saying you can use one cabinet but divided internally.

    I also thought of building these as they had won the Best Iron Driver competition and I had the 830656 drivers, but with my level of skill I couldn't really understand the crossover and it has a lot of parts, which made it costly in Oz.

    I then looked at the 2012 winner, which also used the 830656. It was an MTM using the XT25 tweeter, but that was expensive here, so I eventually built Ron E's "C-notes"MTMs, which are detailed on PETT. They're 1.2 cu ft and came a very close second: they sound very good!

    The XT25 design is also detailed on PETT, I'll find the links and post them if you wish. It used a slot port, from memory.

    Geoff
    I am aware how he did it, I just want to get some more output in the sub 80hz range. 34 litre boxes already assembled.

    Leave a comment:

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