Center channel MTM for Logitech Z-5500.

[ballstothewall 10+ year member]

I love my FF85k's....

 

[bustaplz 10+ year member]

You guys have gotten me all kinds of confused. I'm going to build the original design since the parts get here tomorrow and see how it sounds. I'm really interested in that Fostex driver but I'm not sure I could properly utilize it. Maybe I'll order a couple and try them out as surround channels. Would one of those Fostex drivers and a 6.5" woofer work well in a front channel application? Another worry I have is that those are rated at 10w rms. Each channel on the Z-5500 is rated for a bit over 60w, how much of a problem would this be?

 

[Fast1one 10+ year member]

You guys have gotten me all kinds of confused. I'm going to build the original design since the parts get here tomorrow and see how it sounds. I'm really interested in that Fostex driver but I'm not sure I could properly utilize it. Maybe I'll order a couple and try them out as surround channels. Would one of those Fostex drivers and a 6.5" woofer work well in a front channel application? Another worry I have is that those are rated at 10w rms. Each channel on the Z-5500 is rated for a bit over 60w, how much of a problem would this be?

I am powering my fostex with 50 watts per side. 10W is the mechanical limit, thermally they are taking it fine crossed over at 300hz
Sorry for confusing you so much. Just go ahead and build it and see how it sounds to YOU. If you don't like it, then you can experiment using the two woofers for midbass and a full range driver in the center.

 

[bustaplz 10+ year member]

I am powering my fostex with 50 watts per side. 10W is the mechanical limit, thermally they are taking it fine crossed over at 300hz
Sorry for confusing you so much. Just go ahead and build it and see how it sounds to YOU. If you don't like it, then you can experiment using the two woofers for midbass and a full range driver in the center.

I guess that makes sense, lower frequencies put more strain on the driver? I don't mind being confused ever so often. I've learned quite a bit from this thread. The idea of using a single driver to reproduce vocal range makes a lot of sense, what is the normal vocal range in HZ? I'm a singer/musician so I like to consider myself somewhat educated in the nature of sound but normally I would think of vocal range in terms of octaves on a music scale, never really thought about what that translates to frequency-wise.

Also, I've been looking at building crossovers, it seems like the lower the crossover point, the more expensive and bigger the crossover gets. Is that about right?

 

[Fast1one 10+ year member]

I guess that makes sense, lower frequencies put more strain on the driver? I don't mind being confused ever so often. I've learned quite a bit from this thread. The idea of using a single driver to reproduce vocal range makes a lot of sense, what is the normal vocal range in HZ? I'm a singer/musician so I like to consider myself somewhat educated in the nature of sound but normally I would think of vocal range in terms of octaves on a music scale, never really thought about what that translates to frequency-wise.
Also, I've been looking at building crossovers, it seems like the lower the crossover point, the more expensive and bigger the crossover gets. Is that about right?

Yup, it takes much more excursion to reach the same SPL at lower frequencies. Hence, when tweeters play music you can't see them move //content.invisioncic.com/y282845/emoticons/cool.gif.3bcaf8f141236c00f8044d07150e34f7.gif
As far as frequencies, just start at 20hz and for every doubling of frequency is a full octave. So for the auditory limits of humans (and therefore music), the entire frequency range of 20hz-20khz consists of 10 octaves of information.

Here is a great interactive graph of different instruments with respect to frequencies. Hover over the bands for more information. http://www.independentrecording.net/irn/resources/freqchart/main_display.htm

As you can see, the lower limit of a female vocalist is around 250hz. This is generally regarded as the lower limit of the vocal range, just because with most modern music even males don't go lower than that. Everything below that is generally harmonics.

The upper limit is debated, but the core is generally below 5khz, with sibilance going up to about 10khz. Hence, 10khz is a great place to cross over a tweeter to a full range driver for extra sparkle if it needs it, especially if its a larger (above 4 inch) full range. Its commonly reffered to as a super tweeter, because it plays so high, not because its super //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

As far as crossover points, yes the lower the crossover the point the more expensive the parts get. Thats why I suggest going with a quality full range driver that can dig low.

 

[bustaplz 10+ year member]

Yup, it takes much more excursion to reach the same SPL at lower frequencies. Hence, when tweeters play music you can't see them move //content.invisioncic.com/y282845/emoticons/cool.gif.3bcaf8f141236c00f8044d07150e34f7.gif
As far as frequencies, just start at 20hz and for every doubling of frequency is a full octave. So for the auditory limits of humans (and therefore music), the entire frequency range of 20hz-20khz consists of 10 octaves of information.

Here is a great interactive graph of different instruments with respect to frequencies. Hover over the bands for more information. http://www.independentrecording.net/irn/resources/freqchart/main_display.htm

As you can see, the lower limit of a female vocalist is around 250hz. This is generally regarded as the lower limit of the vocal range, just because with most modern music even males don't go lower than that. Everything below that is generally harmonics.

The upper limit is debated, but the core is generally below 5khz, with sibilance going up to about 10khz. Hence, 10khz is a great place to cross over a tweeter to a full range driver for extra sparkle if it needs it, especially if its a larger (above 4 inch) full range. Its commonly reffered to as a super tweeter, because it plays so high, not because its super //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

As far as crossover points, yes the lower the crossover the point the more expensive the parts get. Thats why I suggest going with a quality full range driver that can dig low.

Sir, that truly is an incredible link. I'm emailing it to myself as we speak, I want to check it out more when I get home from the office. I didn't realize guitar was so low on the scale compared to vocals and even a kick drum. I do think your estimate of the lower vocal range is a bit off. Looking at that chart, I can sing(although not well) below 200hz. On a good day I probably have about 2.75-3 octave range which isn't really that impressive and my voice is most comfortable around G4. There are probably millions of singers who can sing comfortably, with volume lower than myself.

I guess that graph is there to aid in mixing music? Really interesting how low the Tuba and Bassoon reach almost as low as a pipe organ. Also interesting how very little seems to reach down past 40hz. For some reason I've had a sort of aversion to sealed subwoofer enclosures, favoring low tuned ported boxes because I got it in my head that getting a flat response down in the 30hz area was important to me. I may need to build a sealed box for my car and compare a bit.

Seriously, thank you for that link! You've given me something to think about all day. I also had to google Sibilant, this lead me on a tour through a whole lot of words I never knew existed when referring to vocals. I knew about plosives, but wasn't aware the vocal-dictionary was so thick. I'm also stunned/not sure that an acoustic guitar resonates at 80hz, when I get home I'll have to fire up WINISD's signal gen and sit down with my acoustic and see what notes and harmonics fit where.

Maybe you're the person to answer this question:

I have one SR10D4 that I got for a steal after I bought the two for my Jeep sitting around waiting to be put into use. I started messing around with ported box designs, trying to find the most efficient alignment I could as I'll only be giving it 188w and it is rated for 300(it can take a bit more) and eventually stumbled upon Transmission Lines. I've found very little detailed information about TLs online but gathered enough to send me to Home Depot to buy some 12" cardboard tubing. I bought two 4' long pieces as I figured out I would need somewhere around 11' for the Fs of the driver.

Then I found some different information about what kind of diameter the line should be so I'm not sure what to believe. Here are the specs of the driver, I think it is somewhat suitable for a TL, based on some guidelines I've found but I really wouldn't know either way.

10"

Electrical Q Value -Qes: 0.39

Mechanical Q Value -Qms: 5.5

Total Speaker Q Value -Qts: 0.36

Free Air Resonance -Fs: 25.3 Hz

Equivalent Compliance -Vas: 31 liters

One-Way, Linear Excursion -Xmax: 18 mm

Efficiency -SPL 1W/1m: 85.3 dB SPL

Effective Piston Area -Sd: 310 cm^2

DC Resistance -Re: 1.8 ohm

Nominal Impedance -Znom: Dual 2/4 ohm

Thermal Power Handling -Pe: 300 W

Force Factor -Bl: 14.35

The new information I have says that I should keep the TL area to something like 1-1.25x the driver's displacement, or taper it from whatever size I need down to the Sd. Obviously tapering a big cardboard tube is not something I can do, and I can't start a project to do a folded TL right now considering time constraints, the fact that I already have a few audio projects going and the fact that I don't even know how a transmission line will sound and if it will fit my needs. The tubes were something like $28 so it's not as expensive as building an intricate(and probably large) folded TL would be but if the tube style impresses me I will probably try a more refined approach, possibly with a larger driver and a plate amp.

I'm praying you know a bit about TLs as it seems to be a club no one wants me to join and you seem to know just about everything else. The other option is to put the driver into a ported box that is just a bit over 2cubes and tune it low, the curve in WINISD for that looks pretty fantastic for a HT-style subwoofer, lots of sub-bass and a pretty flat curve. But I'm always up for some experimenting and I've built plenty of ported boxes, looking to change it up a bit.

Thanks again for the info you've given me and thanks for anything you can tell me about putting together a transmission line.

Sorry for writing a whole ****ed novel, but I'm just throwing my ideas out.

 

[Fast1one 10+ year member]

TLs are fun but expect to do a lot of experimentation to get it right. Also I would consider doing some negative taper because it shortens the length and dampens the second resonance around the midbass region. Also, stuffing is your friend.

As far as the vocal range, yes I am aware that you can go lower. But for most genres, I have found that there isn't much vocal range below that 250hz mark. Its just a good point to crossover a small midrange/full range in general (convenient).

Yeah I love that link. I always reference it when I can. Very powerful, yet simple diagram.

 

[bustaplz 10+ year member]

TLs are fun but expect to do a lot of experimentation to get it right. Also I would consider doing some negative taper because it shortens the length and dampens the second resonance around the midbass region. Also, stuffing is your friend.
As far as the vocal range, yes I am aware that you can go lower. But for most genres, I have found that there isn't much vocal range below that 250hz mark. Its just a good point to crossover a small midrange/full range in general (convenient).

Yeah I love that link. I always reference it when I can. Very powerful, yet simple diagram.

Well how do you think that driver would do attached to the tube I already have? It would be 12"x8' and the volume of a small box to attach it all together. I can't tell if the dimensions are right or wrong at this point!

 

[Fast1one 10+ year member]

Well how do you think that driver would do attached to the tube I already have? It would be 12"x8' and the volume of a small box to attach it all together. I can't tell if the dimensions are right or wrong at this point!

no taper:
1128ft/s = speed of sound

Lenth =8 feet

Divide by 4 (quarter wavelength)

Divide speed of sound by equivalent length, then divide by 4:

1128/8/4 = 35.25 HZ

That is not accounting for the exit or the outer boundries. Since you are going with a straight taper, I would tune above or below the FS. Don't tune at the FS because the response will be especially ragged. Then experiment with placement and stuffing. Try concentrating the stuffing near the driver or spread out. Also, keep the volume very small, cross sectional area should be near that of the tube. So make it a cube and make the dimensions roughly the diameter of the tube (obviously slightly larger for mounting).

Warning: TLs have two peaks, one at the tuning and one about an octave higher or so. This means its right around the midbass region. To fix the ragged response up top, stuffing will attenuate it. But at the cost of output. So the sub really can't be crossed over higher than around 60-80hz. Not that you should anyway...

 

[vario 10+ year member]

Nice open baffle system on prior page //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

I needed a center so I got two vintage Infinity RS2001 for $10, refoamed and shoved together end on end to be WTTW.

 

[bustaplz 10+ year member]

no taper:
1128ft/s = speed of sound

Lenth =8 feet

Divide by 4 (quarter wavelength)

Divide speed of sound by equivalent length, then divide by 4:

1128/8/4 = 35.25 HZ

That is not accounting for the exit or the outer boundries. Since you are going with a straight taper, I would tune above or below the FS. Don't tune at the FS because the response will be especially ragged. Then experiment with placement and stuffing. Try concentrating the stuffing near the driver or spread out. Also, keep the volume very small, cross sectional area should be near that of the tube. So make it a cube and make the dimensions roughly the diameter of the tube (obviously slightly larger for mounting).

Warning: TLs have two peaks, one at the tuning and one about an octave higher or so. This means its right around the midbass region. To fix the ragged response up top, stuffing will attenuate it. But at the cost of output. So the sub really can't be crossed over higher than around 60-80hz. Not that you should anyway...

I actually put together the TL for my spare RE SR10. I did some experimenting and ended up with it being about 7.75' long and tapered from 12.5" down to ~8" diameter at the end. It's not perfect by any means and I don't have enough polyfill to really experiment with stuffing it, but the transmission line design has convinced me. It has transient response closer to a sealed box than a ported box and massive output from 28hz-45hz compared to the ported box. A 37hz tone will move things around the room and anything from 30-45 will vibrate clothes. I'm actually very suprised by how well it works, I may try to build a quality folded line with a larger driver in the future and do it right. But for something made out of cardboard and a couple pounds of duct tape, it's really amazing. I calculated the tuning and it sits right at 36-37hz(well above Fs) and I've noticed that there is a STEEP drop from 45hz-60hz and another peak a bit above that. It's very strange and has a completely different sound than I am accustomed to, but it's also got a very natural sound down low. I really didn't think a cheap 10" sub off 188w could ever exert the amount of low end force that this does.

Unfortuneatly, the Z-5500 sub amp channel is crossed over WAY too high, but I can't do a whole lot about that. I'll probably end up with a 7.1ch receiver and a good plate amp in the future so maybe I can do some more experimenting with TL designs. I just wish it wasn't so GOD **** BIG. I have the woofer end sitting in a chair, and the open end sitting on a table in the corner of my room. It's the best placement I could find besides laying it on the floor behind my desk chair. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[Fast1one 10+ year member]

What you are hearing is what I was describing. TLs have TWO peaks, one near the tuning and one up higher. What you are probably hearing is ripples in the upper response, hence the drop off...

Glad you are enjoying it. Yes TLs are awesome and very easy to build. A good mix between ported and sealed enclosures...

 

[bustaplz 10+ year member]

What you are hearing is what I was describing. TLs have TWO peaks, one near the tuning and one up higher. What you are probably hearing is ripples in the upper response, hence the drop off...
Glad you are enjoying it. Yes TLs are awesome and very easy to build. A good mix between ported and sealed enclosures...

I'd really like to someday build a proper T-Line with a larger driver. I've seen pictures of folks building folded lines and they look really nice and I toyed with the idea but it would be a pretty drawn out project for me and I don't have the time for it at the moment. I'm amazed at how well this one works for being built out of cardboard and duct/electrical tape. I think if the rest of my system could reproduce mid-bass a bit better the drop off in the TL's response wouldn't be an issue at all. With a good plate amp and some better mid-bass I could LP the TL before the high peak and would have a really impressive low-end.

I can honestly say that the low end from this thing just below what I think is the tuning is BRUTAL when I give it some power, but really well controlled at the same time. I can only imagine what a properly built and engineered TL could do, especially off an amp that doesn't drive into clipping so readily as the Z-5500 does. Fast1one, do you have any T-Line builds? Maybe some direction on a good driver to use for a T-Line? I am kind of wanting to try a 15" woofer as I've never owned one, and am trying to keep my spending somewhat low right now so I'm having a hard time finding good audio projects, but I think I TL may be financially viable. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[its_bacon12 10+ year member]

Hm. All this talk of full range drivers makes me think of one thing: beaming.

There is absolutely no way any full range driver can reproduce the same kind of dispersion patterns as a 2 or 3 way speaker, I don't care who you are it's just not physically possible. OP, that's why when you hooked up those Sony bookshelves, you noticed a less "crowded" sound. Sure, people will argue me on this with their snake oil and stuff but outside of the sweetspot for full rangers, you'll hear little to no treble. Not my kind of speaker. Even Fostex or those CSS mids or even the recently coveted W4-1337 all run into the same problem of beaming and lack of low extension. Even if you did full range, you'd need a notch filter to smooth out response as it can get quite peaky.

As far as the CC you're designing, it is far from ideal by every means and doesn't match anything else in your system but go ahead and give it a try. Like Fast1one said in page one, I'd also advise for 2.5way and have it give you a little more midbass.

 

[ballstothewall 10+ year member]

Have you ever even listened to a quality full range setup?