Acceptable for Satellites?

[HareBrained]

I was talking with a friend about my speaker building experience and how much I'm loving it. It turns out that he's in the market for home theater speakers. We talked about his desires and limitations. He's thinking about a 6.1 set-up and liked several things about a particular Definitive step-up that was a L/C/R sound bar and 2 satellites with a rear center.

I had some questions for him about the available space for the L/C/R so those questions will come later.

For now, his requirements are for small satellites and rear center. From his descriptions, I think I can squeeze 4L out his limitations if I use 0.5" MDF. After a little time researching, I think I simply need to attain ~80Hz out of the satellites. The RS125-4 hits 81Hz in a sealed enclosure, but all indicators say vented. Do you think this would be a good solution?

There is an interesting alternative, using a single Peerless 5.25" PR. in the same sized cabinet. This nets an F3<70Hz and the PR hits it's xmax above the box Fb resulting in sealed-like cone control below that frequency. What's your feeling towards this enclosure?

FYI: The RS125, 4 and S8, really response well to this PR and I'm considering a dual-PR-per-driver alignment for the L/C/R bar (given sufficient surface mounting area.)

Last question is, can the rear center speaker be a satellite or should it be just like the front center channel speaker?

[cjd]

There is no such thing as a "satellite" speaker. Just a small one.

As such, any speaker can be any size - in a HT setup, you just have to tune crossover to sub correctly.

RS150 wants about the same volume as the RS125 sealed yet moves more air and IMO sounds a bit better. Plus there are more designs out there to choose from.

1/2" MDF to get more box volume isn't worth it - you'd use up the difference trying to brace it back to adequate stiffness.

C

[HareBrained]

Excuse my use of the term "satellite" instead of "surround speaker".

Running the numbers, the RS150-4 in 4L sealed has a Qtc=0.94 and F3=79.4. The RS125 in 4L sealed has a Qtc=0.78 and F3=80.2. IMO, the RS125 would appear to be better suited to the task but the RS150 would be louder. Is there any reason the Qtc isn't a consideration?

If I'm using 0.75" MDF, then the available volume is less the 4L.

[---k---]

Are you talking about a single driver speaker? Ie, no tweeter?

[HareBrained]

Are you talking about a single driver speaker? Ie, no tweeter?

No. It would be a TM or TM(PR). I have a budget I'm working to, and spending $40-$50 on the woofer or $25, will greatly impact what tweeter I'll use. I would like to use the most efficient midbass I can find to fit the requirements. I choose a F3<=80Hz because of the Dolby standards. I know the RS125 will probably be ~84db@1W when in the implementation.

The HiVi M5N will actually work in 4.0L sealed with Qtc=0.83 and F3=80Hz. And it should yield another db, but the basket & motor are significantly larger than the RS125-4. The M5N isn't a good candidate for the PR (dual or single), although there are other good alignments for the L/C/R.

[Ray_D]

Zaph's ZBM4

Have you looked at Zaph's ZBM4s? I have built 17 and think they are a great value. I have a built a number of speakers with RS drivers and think they are also a value, but at a significantly higher price especially when you consider the more expensive tweeter.

Incidentally, I have made measurements with the new cast frame driver (55-3853) and with the Dayton ND20FB without changing the crossover and the difference was very small.

I am currently listening to ZBM4s crossed digitally to single RS225s at 200Hz and they sound great.

[Dennis H]

Running the numbers, the RS150-4 in 4L sealed has a Qtc=0.94 and F3=79.4. The RS125 in 4L sealed has a Qtc=0.78 and F3=80.2. IMO, the RS125 would appear to be better suited to the task but the RS150 would be louder. Is there any reason the Qtc isn't a consideration?

Go with the RS150, it's a better driver. Minor differences in Q and F don't mean much in the big scheme of things when you include +/- 10dB room effects. Stuffing will reduce the Q without changing the F very much. Not sure what software you are using but Qa is what stuffing changes -- more stuffing, smaller Qa, and smaller total Q.

[HareBrained]

Have you looked at Zaph's ZBM4s? I have built 17 and think they are a great value. I have a built a number of speakers with RS drivers and think they are also a value, but at a significantly higher price especially when you consider the more expensive tweeter.

Incidentally, I have made measurements with the new cast frame driver (55-3853) and with the Dayton ND20FB without changing the crossover and the difference was very small.

I am currently listening to ZBM4s crossed digitally to single RS225s at 200Hz and they sound great.

I built an MTM using the 55-3853 and the Vifa DQ25 tweeter (used by Zaph in the ZMV5). xover is at 2100Hz, which avoids the rising HD in the xx53 drivers. I love my speakers but the ZBM4 or my TM version just wouldn't be loud enough. It would give up 2db @1W to the RS125 and power handling is down as well.

[HareBrained]

Go with the RS150, it's a better driver. Minor differences in Q and F don't mean much in the big scheme of things when you include +/- 10dB room effects. Stuffing will reduce the Q without changing the F very much. Not sure what software you are using but Qa is what stuffing changes -- more stuffing, smaller Qa, and smaller total Q.

Thanks for the feedback, DH. I've been using Unibox to evaluate the enclosures. Changing the Q's/stuffing is simple.

I've heard high-Q sealed subs, and I haven't been displeased with their sound. But everyone has said that the midrange driver should have a very low Q (oversized) to really make it sound it's best. Although, these are surround speakers and he's set the box size. So, you think the difference in the Q's is not as great as the difference in the drivers. OK. It would make the sound bar simple considering the shear number of RS150 designs out there. :T

I'd still like to hear some other opinions.

[Ray_D]

Power handling numbers are mostly not to be believed.

I built an MTM using the 55-3853 and the Vifa DQ25 tweeter (used by Zaph in the ZMV5). xover is at 2100Hz, which avoids the rising HD in the xx53 drivers. I love my speakers but the ZBM4 or my TM version just wouldn't be loud enough. It would give up 2db @1W to the RS125 and power handling is down as well.

The RS125 has almost the same Sd and Xmax as the 55-3853. The sensitivity may be a little less, but that is only amplifier power. If you need louder you need bigger.

[HareBrained]

I stated the wrong RS150 that functions best, it's the S-8 that functions best in the small sealed enclosure.

[cjd]

When your design is dictated by box size, you do what you can and accept what compromises that brings.

[HareBrained]

When your design is dictated by box size, you do what you can and accept what compromises that brings.

Sage advice, to be sure. I think it can also be said for costs.

So, it appears the RS180S-8 is also capable of "surviving" within the small enclosure. But the shear size of the driver may present it's own problems.

For the tweeter, I was thinking of using the Vifa XT25SC90 ($33.40) with the RS125-4($29.22). If I go with the RS150S-8 ($36.95), I don't think my budget would allow that tweeter. so I'm thinking the Vifa DQ25SC16($15.60).

I used the DQ in my MTM along with a pair of MCM 55-3853, and find it very articulate without being harsh. But I'm hoping the XT would be worth the extra money. Projected net costs of the sets for the entire system (10 woofers, 6 tweeters) would be about the same. Where would the money be better spent, in the RS150 or in the XT? Or is there a better recommendation?

[cjd]

Are you doing measurements and such for a custom crossover? That's still the critical element here I've not seen figured out.

The RS150S-8 + VifaDQ25SC16 would be my pick by a long shot.

XT25 is an interesting beast with mixed-ish results. Not my favorite option. I've not yet heard the DQ but am very intrigued by it.

Another option to consider - for my surrounds I'll be doing a half in-wall box, RS180-4+Seas 27TDFC... half in-wall to get more box volume while taking no more space. Also doing a little bit funky on the box. Some year... but the box thing is the idea I'm talking about here.

C

[HareBrained]

Are you doing measurements and such for a custom crossover? That's still the critical element here I've not seen figured out.

The RS150S-8 + VifaDQ25SC16 would be my pick by a long shot.

XT25 is an interesting beast with mixed-ish results. Not my favorite option. I've not yet heard the DQ but am very intrigued by it.

Another option to consider - for my surrounds I'll be doing a half in-wall box, RS180-4+Seas 27TDFC... half in-wall to get more box volume while taking no more space. Also doing a little bit funky on the box. Some year... but the box thing is the idea I'm talking about here.

C

I am seriously thinking of using this opportunity to assemble a measurement system. I used the IB measurements of Zaph for my MTM and am very happy with the results. But I think there was some luck involved.

The DQ is an incredible value. I have a set of MDT40's with a well designed xover (IOW, I didn't design it) and although the MDT's do sound better (I could only notice the difference with good source material), without them side-by-side, I wouldn't know what the DQ was missing anything. There's nothing about the DQ that you can point to as a flaw. It's very well balanced. You need to play with a pair.

I would love to use the RS180-4/27TDFC combo. The 27TDFC has certainly been mentioned in very high regard. But besides the costs, the room these are going into is a post-and-beam construction, and as such, no wall cavity to speak of. The box needs to fit "behind" a post or beam. He doesn't want any overhang.

[cjd]

Yeah, I didn't figure my speaks would work for you. Just the partially in-wall concept. Which also won't work I guess.

Measurement rig is the easy part. Figuring out how to get it to work consistently... a bit tougher.

[fjhuerta]

I second cjd's vote for the Vifa DQ25. I just built a ZDT3.5 with those tweeters, and they are excellent - very easy to work with, and according to Zaph measurements, will do 2 KHz at 4th order without any issues.

Be careful with their domes, though. I was (a bit) careless and I ended up dinging two of them. It had never happened before!