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Post by topdown on Dec 18, 2011 16:34:21 GMT -7
Hi Thomas, After becoming discouraged about my attic situation earlier this year, I believe I have found a way to work in an IB manifold directly above the TV. During the last 6 months I ended up building a pair of 4.3cf ported enclosures with Oaudio TC2+ 12's that I got for a good price. Running the pair with an Oaudio 500w BASH amp. I really like them for music but for HT I find myself wanting more. This weekend I picked up a Samson SX1200 (450wpc into 4ohms) very cheap and have been thinking about a pair of Fi IB3 18's. The WinISD overlay looks good (see attached) - I certainly don't need more SPL - I just want more low end. Is the Samson a good choice for this? Are there any characteristics I am going to be trading away with this switch that I will miss? It looks like with 450wpc I am going to need some kind of HPF, a 10hz butterworth would keep excursion under control - is there something better to do here? My HTR is the Onkyo 805 and my mains are Martin Logan Sequel II's. No center channel. My attic is cathedralized foam and I estimate the volume around 5000-6000 cu ft. Living room is 24x24x8 and it opens into a 19x19x8 kitchen/dining area. Thanks in advance for any advice! Attachments:
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Ile
New Member
Posts: 48
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Post by Ile on Dec 19, 2011 6:15:30 GMT -7
It looks like with 450wpc I am going to need some kind of HPF, a 10hz butterworth would keep excursion under control - is there something better to do here? That is your amps max output, but you are using 6W with 100db (3mm excursion). So it depends about your listening level. If you adjust amp gains to match your mains volume, most mains will blow long before two Fi's will be bottoming.  HPS will limit lower output that you are after. I have two of those Fi's without HPS and can barely see cones moving with my normal listening level. |
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Post by topdown on Dec 19, 2011 7:09:57 GMT -7
Thank you for your input. Yes, at 700w I am safe without a HPF and still reaching levels I can't imagine. Even at 500w I am matching the highest levels I have dared try with my current setup.
Does anyone know if the Onkyo 805 will output enough voltage to drive the Samson to full power? If not, is the Cleanbox the way to go or are there other choices?
Does anyone apply any boost below 20hz or is that just asking for trouble?
Can Audyssey EQ this or should I get a miniDSP?
Thanks for any and all input!
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Post by ThomasW on Dec 19, 2011 7:22:51 GMT -7
Very few people need a HPF provided they use a little common sense regarding how loud the system is being operated.
The Onkyo's owners manual spec page should have info about the drive voltage available from the sub out.
My guess is that once you have an IB sub operational the ported boxes won't be needed.
I've never used a system with an Audyssey, people seem to either love them or hate them.
Don't really see any benefit of the MiniDSP over the Behringer BFD
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Post by FOH on Dec 19, 2011 18:11:13 GMT -7
Yes, at 700w I am safe without a HPF and still reaching levels I can't imagine. Even at 500w I am matching the highest levels I have dared try with my current setup. With music, it'd be tough to reach the limits with that amp, those drivers. With Bluray playback, you could encounter the excursion limits if the spectral energy was centered at 20hz and below. With big broad spectral effects, perhaps the amp would be spread too thin to hit the driver's limit. Does anyone know if the Onkyo 805 will output enough voltage to drive the Samson to full power? If not, is the Cleanbox the way to go or are there other choices? Looked around, couldn't find the sub pre out voltage of the Onkyo. You may not need any level shifting at all, however if you do, the Behringer MIC2200 accomplishes that with two bands of fully parametric EQ (down to 10hz), it's also got defeatable/variable high pass filter beginning at 12hz on up, and most importantly in this case, plenty of gain/level boosting and it's $99. Pay no attention to the back-lit vacuum tube recessed in the face  Does anyone apply any boost below 20hz or is that just asking for trouble? Yes, and yes, it's asking for trouble! Typically, if you're careful, and exploring the limits carefully, you can boost away....just exercise caution. Operational headroom, both amplifier and driver limits, gets used up quickly with aggressive EQ'ing @ 20hz and below. Can Audyssey EQ this or should I get a miniDSP? I'm not a big fan of the miniDSP for this application. Audyssey could work, but I've no first hand experience with it either. I've read very savvy enthusiasts, with entirely different opinions of it for this use. I'm familiar with one user that uses Audyssey for his JBL mains, and (8)LMS5400's subs in his HT. AFAIK, he still exclusively employs Audyssey for his subs signal shaping with good response down to single digits. To me, it seems a bit unpredictable, I'd prefer more specific control. Good luck |
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Post by topdown on Dec 21, 2011 10:56:18 GMT -7
Thanks for your input and suggestions. The output voltage on the Onkyo is reported to be 5.5v max so I think I'm okay there.
I'm curious why you feel the miniDSP isn't such a good fit. I have actually had a good Audyssey experience so far and will try that first, but was thinking miniDSP for plan B. (I had an 1124 but sold it)
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Post by topdown on Feb 8, 2012 14:39:08 GMT -7
Here's my first pass with REW with the IB sub. This is a baseline reading (average of three measurements) with no Audyssey or any kind of EQ applied. I don't have a clue what I'm doing with REW - does this look reasonable? Anyone have any suggestions for taming rattling 6" Halo light cans? Attachments:
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Post by topdown on Feb 8, 2012 14:40:52 GMT -7
I should add that the LFE crossover is set at 80hz, as are the mains (no "double bass").
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Post by ThomasW on Feb 9, 2012 7:35:39 GMT -7
Anyone have any suggestions for taming rattling 6" Halo light cans? Use liquid nails on the parts that aren't removable, the rest damp with rope caulk aka Mortite |
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Post by chrisbee on Feb 9, 2012 9:08:19 GMT -7
Here's my first pass with REW with the IB sub. This is a baseline reading (average of three measurements) with no Audyssey or any kind of EQ applied. I don't have a clue what I'm doing with REW - does this look reasonable? The response curve is very odd. Comb filtering springs to mind. If you were to set the vertical graph limits to the standard 45-105dB it would be even more pronounced. You are also testing at far too high a level for domestic comfort. |
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Post by topdown on Feb 9, 2012 19:31:22 GMT -7
Thanks for the tip on the rope caulk. I thought that first graph was odd too. Not sure what I did, but here's another one. Does this look more reasonable? Attachments:
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Post by chrisbee on Feb 10, 2012 4:59:26 GMT -7
Much better. BTW: I always like to see a first graph with the REW .cal correction curve, a little smoothing and proper graph limits set. Just to save having to mention it every single time. If you have EQ take a few dB off the 23Hz peak and leave the rest well alone. Just while you get a feel for the SQ. If you have any mobility to your seating arrangements try moving the test microphone/SPL meter backwards or forwards. Just to see if it helps to flatten the curve naturally. No point in EQ-ing if the curve is much better a foot in front or behind your favourite seat. Be careful to test at ear level too. There is often a lot of response variation with the test microphone height. |
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Post by topdown on Feb 10, 2012 7:31:21 GMT -7
Thanks for the feedback. I am hopefully picking up an FBQ2496 from CL today. I'm still stumbling through the REW learning curve but depending on what correction limits I set it is recommending between 9 and 11db of cut at 23.5hz. Before I do anything I am going to take more measurements as this first one is a few feet in front of the listening position just due to limited cable length. Here's a photo of the mostly finished install. There are two Fi 18's in a manifold about 12.5" x 20.5" ID. I got really lucky on the grill cloth color. The grill is held in place with four cheapie magnetic cabinet latches from Home Depot. The Samson SX1200 amp is up in the attic. I still need to rig up a relay to have it turn on and off with the receiver. Attachments:
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Post by chrisbee on Feb 10, 2012 8:45:47 GMT -7
A shrine to audio heaven.  I couldn't find the stealth IB.  The graph limit adjustment is in the box at top right of the REW screen once you have a measurement. 45-105dB vertical. 5 or 10-200Hz horizontal. It will become easier with time. Just getting a graph on the screen is an achievement in itself. |
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Post by FOH on Feb 11, 2012 8:31:18 GMT -7
Yep, nice pic,...clean room.
How's it sound? Nothing on the walls, nothing on the floor,....it appears to me to be screaming for a good measure of room treatment.
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Post by topdown on Feb 11, 2012 22:34:39 GMT -7
There is a large floor rug just in front of what you can see in the photo, and a couple of sofas, but I suppose the clean look isn't the best for acoustics.
Still, I have spent a lot of time on positioning the Sequel II's and I think it sounds great. Female vocals like Allison Kraus or Ginny Owens are incredible, as are strings. For music I tend to prefer putting the Onkyo receiver in "pure audio" mode which sends everything to the Sequel II's. I usually don't play music that loud and the bass the sealed 10's deliver is plenty for my taste. The Onkyo runs pretty warm when it's handling the stuff below 80hz so I have to be careful.
For cranking stuff like Larry Carlton's "All Thru the Night", "Thinks We Said Today" or watching a movie, the IB is amazing. Four of these drivers would be crazy. I'm sure it could use a little eq work (struck out on my FBQ2496 deal), but right now my biggest issue is light cans buzzing and I am still searching for the elusive rope caulk. I watched a little bit of The Incredibles tonight and felt things I never felt with the two ported 12's. The Oaudio 12's would smoke any store bought sub, but 900w on a pair of Fi IB3 18's is a whole new experience. The stealth setup is just icing on the cake.
I installed a relay and mini-jack in the Samson amp today so I finally have it switching on & off with the receiver. I still need to put a dedicated outlet up in the attic so I can get rid of the extension cord dangling out the access hatch in the garage. The Samson SX1200 performs well, is a much cleaner layout inside than the Behringer, and has a parallel mode so you can wire the drivers as if running stereo but run with just one input cable. The Onkyo has plenty of LFE output to drive it to full volume so I'll be selling off my Henry Engineering Matchbox II if anyone needs one.
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Post by ThomasW on Feb 12, 2012 8:03:03 GMT -7
I am still searching for the elusive rope caulk. Shouldn't be elusive, look in the weatherstripping section of any hardware or big box store |
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Post by FOH on Feb 12, 2012 11:57:20 GMT -7
"There is a large floor rug just in front of what you can see in the photo, and a couple of sofas, but I suppose the clean look isn't the best for acoustics."
What's important is how it sounds to you. I've not spent a great deal of time with dipoles in my room, so I can say much wrt optimizing them. I'm sure they sound fine. I've heard a similar rig, in a similar acoustic, ...and it was nice for music.
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"The Onkyo runs pretty warm when it's handling the stuff below 80hz so I have to be careful."
Interesting, no biggie? impedance drive issues?
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"For cranking stuff like Larry Carlton's "All Thru the Night", "Thinks We Said Today" or watching a movie, the IB is amazing."
I love seeing someone mention music tracks by name in here,...thanks for that.
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"I watched a little bit of The Incredibles tonight and felt things I never felt with the two ported 12's. The Oaudio 12's would smoke any store bought sub, but 900w on a pair of Fi IB3 18's is a whole new experience. The stealth setup is just icing on the cake."
Sweet huh? The Incredibles is a superbly done mix, sound design by the great Randy Thom. If he's associated with the design team, there's some deep, nicely done LF effects.
Also, for music, yeah, four 18's may be a bit much. But for some effects like Randy Thom utilizes, that extra capability can be gobbled up in a flash. At a given SPL, lowering the frequency by one octave requires a 4x multiplier in driver displacement.
Good luck
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