DIY sub for Klipschorn based HT (and music) - Tuba HT - build done (except for finish)!

[CECAA850]

It would be great if fellow THT onwers would tell me what SPL to expect at a given distance, voltage and frequency. Thanks!

SPL is giong to be a product of placement and the room. Fellow THT owners can give you measurements that they get but there's an excellent chance yours will be different. The only way to compare your subs specs vs someone elses would be using a ground plane measurement outside. You have to compare apples to apples. The subs have to be measured in the same manner to have a useful comparison.

[nyt]

Peter,

I don't know if this will help you that much, but here is a video going from volt meter to spl meter at my LP, which is 15' from the mouth of each sub.

[psg]

Peter,

I don't know if this will help you that much, but here is a video going from volt meter to spl meter at my LP, which is 15' from the mouth of each sub.

Ouch. Thanks, I wanted examples so I'd know when I get to where I ought to be. Currently, I have 2W for 100 dB or so. I can extrapolate to 114 dB for 50W. You had two THTs, so 6 dB gain for that. That would get me to an equivalent 120 dB. So I'm within 5 dB of yours and I think I can do better with front placement. Ok, getting there and not too bad! I can see why people would get two! []

[psg]

Tried the front of the room, at the corner in front of the left KHorn. The pictures shows how big it is even next to a KHorn, and how huge it is next to a Hsu STF-3. I got about the same response at the sweet spot and a couple dB more on the seat over. The opposite corner of the room gets 10 dB higher! Anyway, the performance would have needed to be outstanding for it to stay up front; it's so huge!

[psg]

I have placed it back facing the side wall, where it does best for now. But since I have felt under it, I can slide it around easily. This weekend I will run sweeps from a variety of possible and impossible positions, just to get a sense of what I can do with the room.

There no sense in doing too much of this since the suspended ceiling is not in yet (although I have 6 inches of sound insulation already up there) and the walls are not treated. Perhaps a bass trap on the opposite wall would fix it right up.

I am also intrigued by an in-wall installation I have seen on AVS. The sub could be in the adjoining utility room in the back, with only the mouth firing into the room (IB style). Of course there's no final wall reflection with this, but it's still 1/4-space no perhaps sensitivity isn't lost? I have a doorway to that utility room. I could try placing it there to check it out. I'd hate to cut a hole on that new wall and get awful response out of it. Kinda hard to test accurately...

For now, it plays louder, lower, cleaner and with smoother frequency response than the Hsu STF-3 it replaces. A bit of EQ with miniDSP and perhaps moving it in the room should get me more. I wonder if I can use two channels of the miniDSP to setup a flat EQ on one channel and a house curve on the other, so that I can switch (manually) between them. That would be cool.

[Vicoaster]

Peter, can you post a link for the post on the AVS forum for a in wall mounted Tuba? Thanks!

[ClaudeJ1]

I have placed it back facing the side wall, where it does best for now. But since I have felt under it, I can slide it around easily. This weekend I will run sweeps from a variety of possible and impossible positions, just to get a sense of what I can do with the room.

There no sense in doing too much of this since the suspended ceiling is not in yet (although I have 6 inches of sound insulation already up there) and the walls are not treated. Perhaps a bass trap on the opposite wall would fix it right up.

I am also intrigued by an in-wall installation I have seen on AVS. The sub could be in the adjoining utility room in the back, with only the mouth firing into the room (IB style). Of course there's no final wall reflection with this, but it's still 1/4-space no perhaps sensitivity isn't lost? I have a doorway to that utility room. I could try placing it there to check it out. I'd hate to cut a hole on that new wall and get awful response out of it. Kinda hard to test accurately...

For now, it plays louder, lower, cleaner and with smoother frequency response than the Hsu STF-3 it replaces. A bit of EQ with miniDSP and perhaps moving it in the room should get me more. I wonder if I can use two channels of the miniDSP to setup a flat EQ on one channel and a house curve on the other, so that I can switch (manually) between them. That would be cool.

You may want to try putting in the sweet spot. Then just walk your mike around to find the best response you are looking for, then move the Tuba there.....reverse engineering in style......

[psg]

You may want to try putting in the sweet spot. Then just walk your mike around to find the best response you are looking for, then move the Tuba there.....reverse engineering in style......

Still need to turn the mouth around, so I'm not sure if that trick works with a THT.

Here's the AVS link:

http://www.avsforum.com/avs-vb/showthread.php?t=1213414

[Q-Man]

In my home theater I cross over to the sub at 45hz. I have Klipschorns and an Epik Conquest subwoofer. In my rather large room the 45hz cut off sounds best. At 40hz the bass is lacking, at 50hz the bass begins to sound muddy.

Once your set up, just sit back and and listen to music and movies and play with the crossover setting in your AV processor or receiver. Also listen at different volume levels. Crank up the volume and change the crossover settings on the fly. The perfect crossover point for your speakers and room will be easy to hear.

Q.

[ClaudeJ1]

In my home theater I cross over to the sub at 45hz. I have Klipschorns and an Epik Conquest subwoofer. In my rather large room the 45hz cut off sounds best. At 40hz the bass is lacking, at 50hz the bass begins to sound muddy.

Once your set up, just sit back and and listen to music and movies and play with the crossover setting in your AV processor or receiver. Also listen at different volume levels. Crank up the volume and change the crossover settings on the fly. The perfect crossover point for your speakers and room will be easy to hear.

Q.

Excellent advice. I tend to agreee with your from my experience with the large VMPS subs and Khorns at my old house. 60-40 Hz. range sounded best to me, depending on program and subwoofer location in the room.

[psg]

Thanks. I already find that detecting the sub at any crossover is harder with the THT than with my previous ported sub. Horn-loaded bass is horn-loaded bass I guess, and it blends in well. But I haven't listenned to a lot of music yet.

Yesterday I did REW sweeps with the sub at various positions and a variation on my initial position is best. If I ever built a second I would hide it in the adjoining room with just the mouth connected through a hole in the wall. That could help even out the bass and provide extra headroom. On the other hand, it may not be needed in most applications. We watch The A-Team in Blu ray last night , about 10 dB below reference, and the sub never got more than 10 Watts or so. That would mean 100 Watts at reference, but we never watch that loudly anyway.

I'll post REW sweeps soon.

[ClaudeJ1]

So, fellow French Canuck, how does it feel compared to a DR bass?

[psg]

Very easy integration with Klipschorns. I switch crossover frequencies and can't tell the difference! I still need to implement high-pass filtering and lower a bump around 30 to 40 Hz, and so will be ordering a miniDSP soon. I watched How to train your dragon last night, but just a bit too low in volume (because of the family) to fully appreciate the LFE; I have to try again at closer-to-reference volume. But the output is so clean that you think the SPL is lower than it is.

[psg]

Here's afrequency sweep for the Klipschorns as large. I don't believe the reponse below 15 Hz or so. Calibration artifact.

[psg]

Here's the THT with crossover in the receiver set to 200 Hz. Again, disregard the increase below 15 Hz. The response drops like a rock below 18 Hz and I have a big between 30 and 45 Hz and I could reduce. The 125 Hz and 160 Hz nulls don't always show up this strongly.

[psg]

Here's a combination with crossover point set to 80 Hz. The dips around 160 Hz are intriguing, because they seem to be coming from the sub (they are not in the Klipschorn response), yet the crossover point is lower than that at 80 Hz.

Won't be too bad if I trim that 30 to 45 Hz bump, unless I go for a house curve anyway.

[ClaudeJ1]

Very easy integration with Klipschorns. I switch crossover frequencies and can't tell the difference! I still need to implement high-pass filtering and lower a bump around 30 to 40 Hz, and so will be ordering a miniDSP soon. I watched How to train your dragon last night, but just a bit too low in volume (because of the family) to fully appreciate the LFE; I have to try again at closer-to-reference volume. But the output is so clean that you think the SPL is lower than it is.

Yes you never knew how much harmonic distortion and slow response you had before until you switch to horn subs.......very low group delay.

[CECAA850]

I noticed that every graph had a dip around 50 Hz, it's more than likely your room. That's too bad as that's where a lot of slam is, You might look into bass traps.

[psg]

I agree with your assessment. It's gotta be the room.I thought bass traps were to avoid peaks, but I guess they would have the same effects on negative reinforcements as well.

Any suggestions for bass traps?

I have two large rolls of foam that one uses under flooring. I moved them around the room with no effect. I guess that material doesn't make a good bass trap.

[CECAA850]

Bass traps help to prevent the sound waves from bouncing back into the room and interacting with the waves your sub is producing. I bought mine from GIK but there's tons of tutorals on the web if you're interested in building your own. The main reason I bought mine was because I didn't think I could build something that would be presentable in my living room.