Frugel-Horn Sub-Woofer

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Jump to Latest
A

AlexQS

Member
Joined 2012
planet10 said:
I don't actually have a drawing (yet). The design process went like this (and probably over the phone): let's do a right triangular prism the height of the FH3 big enuff to give the 14-17 litres needed to accomodate a sealed SDX7. Shortly thereafter proto-units appeared at my door.

Here is a quick picture.

attachment.php


The key to making a helper woofer work is extended top end (700-1000 hz minimum). Many dedicated subwoofers don't qualify. But there are tons of decent midbasses.

It would probably work a bit better as a deflector if the angle was as in the FH1, but we chose 45 degrees since it is a less complicated build.

One could also do it as a diamond shaped prism for more volume.

dave
Click to expand...

Hi, I need some advice on a pair of woofer boxes to go with a pair of FH3 with Alpair 7.3

I'm excited, just picked up a few sheets of 13 ply BB today :D

I happen to have four Eminence Eminator 2515. I got them because my goal at the time was efficiency, and they're 94dB/w/m with a low Fs, and were very inexpensive. Currently there's two in a rediciously huge (330 liter) bass reflex.

I'm thinking I'll try them in a sealed box, as I'm hoping to find crisper, cleaner, tighter, etc (I know subjective terms,... sorry -I listen to jazz, classic rock, no rap or hip/hop, and I'm not worried about movies at this point)

I'll try to keep this short:
I calculated some interior volumes for right-angle prisms, drew one up in sketch-up, etc:
  • Looks like if I put one in a sealed enclosure of ~80 liters I can have a Qtc of ~.704
  • If I go bigger, ~145 liters comes to Qtc .588
  • If I go aesthetically as large as I can, that would be 21inch, 21 inch, 29.7 inch, 60 inch tall, the interior volume will be 182 liters, with a Qtc of .551

    I'll attach a photo with some of the things I was looking at in Jeff Bagby's excel sim (includes some T/S of the driver).

    Can someone please make a suggestion? I'm sure a different driver would be a good suggestion, but for now I want to try to use the drivers I have on hand with miniDSP.

    Will a sealed arrangement work for this Eminator 2515 woofer? Should I try to figure out a tapped horn or something else instead?

    Looking forward to any suggestions about the best way to try to incorporate this driver to compliment Frugal Horns.

    AlexQS
 

Attachments

  • diyaudio stealthwoof idea.jpg
    diyaudio stealthwoof idea.jpg
    113.2 KB · Views: 484
  • Eminence Response.jpg
    Eminence Response.jpg
    103.5 KB · Views: 470
Scottmoose

Scottmoose

Member
Joined 2005
wodendesign.com
Qtc is going to vary somewhat depending on the internal damping type & quantities. 145 litres with a fairly heavy stuffing density for e.g. should get you into the region of the 'optimum' 0.5 (critically damped). Gain is another issue; it won't be massive under anechoic conditions; F3 being 63Hz or thereabouts, notwithstanding step-loss etc. With lighter damping, you should still be in the Bessel region, so not too bad. If they're loaded into corners, assuming reasonably solid boundaries, the latter will become a non-issue, and you should get significant lift down to about 40Hz, before any EQ you may wish to add.
 
J

jjcarr

Member
Joined 2007
dbailey said:
Hi,

I'd like to hear from people who have matted a sub-woofer with Frugal-Horns. Did to find a sub what complemented the frugal's particularly well? Any subs that just flat out didn't mate with the frugals?

Any other full-range and sub comment/recommendations will be appreciated.

For what its worth, my amp is a RH84 with 12at7 driver, my source is a Squeezebox Touch. My listening room is 12' x 9' x 20' and my music listening preference is electric blues.

Thanks in advance four your input.

Cheers,
Dave
Click to expand...

I've found the Martin Logan Dynamo, the original with 10" driver and 10" passive radiator works well if you want to add a good low-end. It's more musical than most subs and can be had on the used market for around $200-$250. I use a Grotto now myself, which is like the Dynamo with more adjustability.

Keep in mind, when you integrate the sub, don't let the signal that goes to the FH's pass through the crossover in the sub. Run it in a FAST configuration, where the speaker is full-range and the sub is just low-fill.
 
A

AlexQS

Member
Joined 2012
Thank you Scott. I'll plan my cut sheet for 145 liters and cross my fingers. I realize this isn't the most ideal driver for this application, but I'll let you guys know how it works out. A more appropriate woofer may be next years upgrade.

jjcarr, thank you too. Great suggestion to run the Alpairs FR.

Dave, you mention importance of crossing around 700 to 1000Hz. Why is this a key making it blend well? How low in frequency will FH3 play? I figure if they come down to 50 or 60hz, then I should cross an octave above at 100hz or 120hz. I think the 15" woofer should play up to at least 250hz pretty well, and that's slightly more than octave above the 120hz for the low pass. I have the flexibility of DSP, so I can experiment,...but good results are always found sooner when I follow good advice. Please let me know your thoughts about crossing at 700 to 1000 vs crossing at 100 to 120hz range.

Thanks again.

AlexQS
 
A

AlexQS

Member
Joined 2012
Oh I see. That makes sense. I might just be in luck! Looking at some measurements I took a while back, a near field, 1m on axis, and 1m windowed at 5ms; there all a little wavy, showing a droop around 250hz to 350hz, but it falls off a cliff at 1100 down 25dB by the time the frequency reaches 2000hz.

Thanks again for everything.
 
J

JoeyGS

Member
Joined 2007
What's a good alternative now for the CSS SDX7? Planning to make this stealth sub.

And what would be the desirable specification of a sub driver to be matched with the FXHL/MA 10.3?

chrisb said:
Which FHs?

Yup, a "sub" or more accurately described, bass augmenter, can be very helpful with either of the FH designs. We've been quite happy with results with CSS SDX7. We use them a lot, mostly because we happened to acquire a goodly quantity thereof, and they can fit into very small enclosures - but any decent 6-8" driver such as TangBand, Silver Flute, Peerless, etc should suffice.

This might be as a good a time as any for Dave to post sketch of the "stealth" design - basically a triangular prism enclosure that sits in the FH's rear firing mouth acting as a deflector, and with the driver mounted on the rear panel. Due to dimensional constraints, it works best with external amp.
Click to expand...
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Top Bottom