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Old 22nd July 2013, 11:45 PM   #1
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Default Fostex horn w/ sub

I've been a lurker on here for a while. I'm fairly active on Home Theater Lounge (formally HTT) and some what over on AVS.
I feel the advice I need will best be found on this site.
Over the 4th my brother and I built a set of BK-12 kits for the Fostex FE126En. I'm about to buy the drivers. I'll do the tips I read to do to the basket; duct seal putty and felt on the magnet. Cheap tweaks that can't hurt.

Here is a pic from my phone. Once I get the drivers, I'll use a better camera. (that's an Adire 81 in the background. My HT system is all Adire.)

Click the image to open in full size.


We used black and red paint, stressed it and then sealed it. It was cool to do this with my brother. He's the master carpenter of the family.

This is my first experience into full range drivers. These aren't for jamming and rocking the house. I have a system for that. That said, I feel I may need a sub to fill out the bottom end. I've heard it can be a challenge to integrate horns with a sub. I'm going to try a tapped horn with a 8" or 10" like what Lilmike's Cinema T-6 designed over on AVS. I have a Dayton 10" Classic or the MCM 55-2421 to choose from.

Eventually I'll build a tube amp kit. For now these will be driven with SS amps. I have an Adcom GFA-555 and GTP-500 that's collecting dust that I hope will do the trick for now. While it's WAY too much power, I'm not going to crank them. I may buy a small SS amp from PE if the Adcom is too crazy to control.

Anyway, on to the point of this thread. What are the challenges of matching a sub to these drivers? The sub "should" be around 92db efficient. I don't recall what the Fostex are in the BK-12. Anyway, I guess it's all about playing and seeing how it works huh?!!! Any suggestions? Is it worth trying to add a sub? I listen to all kinds of music; jazz, classical, rock, country, classical. But this will be my jazz/classical system.

I love this hobby. There are many upgrades to come, it'll be like a whole new system each time.

My next biggest decision is what tube amp kit and what upgrades. That's for another thread later.

All thoughts and opinions are appreciated!
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Old 23rd July 2013, 04:56 AM   #2
chrisb is offline chrisb  Canada
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Michael - a few random thoughts

The BK12 or any BLH does not increase the overall efficiency of the driver, and assuming that the woofer(s) will be separately powered, you probably needn't worry too much on matching the sensitivity of the woofer to the main system.

The Dayton seems like a great bang for the buck driver, you're probably already aware of its positive reviews. The questions would be which enclosure type would most closely match the dynamics of the FE126/BK12, and are you constrained by physical size.

FWIW, I'm of the opinion that a pair of smaller woofers offer a lot of advantages over a larger one, even when XO'd low enough to run in mono. A quick way to test that might be to borrow something for the Fostex and run the Adires as subs with a quick 'n nasty passive line level XO and the Adcom pair. Of course, you might already have enough spare amps lying around ( if not, you likely soon will )

edit:
I just reread your opening sentences, and realized that you probably already have all the signal processing and amplifier channels you need for such testing in the form of a surround receiver.
Set up the speakers with mains (BK12) as small, no center or surrounds, and experiment with the XO frequencies to LFE channel starting around 80Hz. Note that the higher you raise the XO, the more dynamics and SPL you can achieve with the Fostex before distortion.



I've built a few dozen or so subs, and am a huge fan of outboard amps for these whenever space is not at a premium - the Dayton APA150 is a great candidate for this application. I includes an adjustable LP XO, but for maximum system improvement, it's still a good idea to HP the Fostex drivers.
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Old 23rd July 2013, 08:03 AM   #3
Squeak is offline Squeak  Denmark
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To use your horns for what they were build to do, I'd say pass at 80 - 100 Hz, depending on the filter type, seeing as the Fs is 83.
If you are not going to play loud, like say 85 dB, you'll get very little cone movement in a horn.
Beautiful cab BTW.
Looking at the hole cut-out I think I see two crucial things missing though (esp. for a featherweight paper driver). 1: Chamfering on the inside of the driver hole (not where the screws bite though). 2: Padding on the side walls (ideally something thicker and more sound absorbent than polyfluff).
Both things can still be easily done through the hole with a little care though. Use a rasp to chamfer and clue some felt to the inside with a few spots of contact glue.

Last edited by Squeak; 23rd July 2013 at 08:08 AM.
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Old 23rd July 2013, 02:51 PM   #4
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Thanks for the response guys.

I will be playing a bit with tweaks.

Squeak, I will be adding some padding on the inside. At least to the areas I can reach my big old hands into. In my research for this cab, I didn't see anyone else use it, but want to try anyway. And I'll chamfer the holes once I see how the drivers fit. Good tip! I want to make the drivers easily removable so I can play with the polyfluff to fit my taste.

I've heard some good things about this amp, so it's one I'm willing to try. If it sucks, it will find it's way to the garage system.

Amazon.com: FiiO A1 Mini 2x14W Class-D Digital Audio Amplifier: Electronics

I'll definitely be playing with the XO when I add a sub!

Gotta scoot. Break is over!
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Old 23rd July 2013, 08:10 PM   #5
chrisb is offline chrisb  Canada
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If you haven't already pushed the order button on the FiiO, another line of T-amps to consider is Topping - everything from 15 to 60WPC. I have a TP30 at both home at work computers driving Fostex FF85WK - the USB input sounds way better than it has any right to at the price.
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Old 23rd July 2013, 11:12 PM   #6
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Quote:
Originally Posted by chrisb View Post
If you haven't already pushed the order button on the FiiO, another line of T-amps to consider is Topping - everything from 15 to 60WPC. I have a TP30 at both home at work computers driving Fostex FF85WK - the USB input sounds way better than it has any right to at the price.
I did see those too. Guessing, they are both a good line. I wouldn't mind A/Bing them! For the price, if I don't like the Fiio, the Topping would be next. I didn't NOT pick the Topping for any reason. Just picked the Fiio.

I read a few good reviews on the Fiio and decided to pull the trigger last night. <shrug> We'll see!
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Old 23rd July 2013, 11:35 PM   #7
chrisb is offline chrisb  Canada
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We've all pulled the trigger on spec / rumor at least once . I recently did myself for some gear for a small restaurant system - Dayton house brand 12 channel amp ($449) and NuForce Icon iDo DAC/pre amp ( $140). For a simple iPod based background system it's drop dead simple and works like a charm.
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Old 24th July 2013, 12:43 AM   #8
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The FiiO is based on NXP chips. Be interesting to compare to the ubiquitous T-amp.

dave
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Old 24th July 2013, 01:11 AM   #9
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While I don't have a T amp handy, I'll certainly report back on the FiiO.

As I mentioned in my first post, I have a few things to play with. I forgot to add I have a Lepai DMA215. I can't find info on it other than what is on the box and it states 2X15. LOL This thing is huge! I got it free from PE when I bought some Dayton B652 bookshelf speakers. The SD card doesn't work. For free, it was worth every cent!
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Old 24th July 2013, 02:32 AM   #10
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If I have some extra cash maybe I'll pick up a T amp just to see. I have about 5 setups to play with; a Lapai, old Pioneer SX-6, Adcom, Emotiva and now the FiiO. The FiiO is the most practical for now. I can report back if anyone is interested.
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