Contemplating a budget MTM project using full/extended range speakers

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Hi all, it has been some time that I did not post here. I have recently built my first DIY project with the help of a carpenter and the guys at the avsforum. It was a Dayton sealed RSS460 18 inch subwoofer powered via a crown XLS 1000 watts amplifier. I am still ameliorating this design, I am getting for it a larger amplifier for now, either the inuke 3000dsp or the 6000dsp for future proofing, and mainly to use the DSP for low frequency equalizing. Later I might build a ported box for it to better cover my space.[/SIZE]

My room is on the large side, it is a saloon and am living in a building. The room is 10.5x4 meters open to other areas, and has a 3 meter ceiling. However, the sitting area for HT viewing is around 4x4 where I have put the subwoofer, surround speakers, and center.

My mains are currently the Energy take towers 3 ways speakers (power handling 250 w rms) formed of 4x4.5 inch woofers and 1 inch tweeter. They are nice speakers but currently seated at the far end of the saloon i.e 10 meters from the sweet spot in the listening area. They are complemented by an energy center speaker of two 4.5 inch and a tweeter with 2 passive radiators situated at 3 meters from the listening area sweet spot; and for surround speakers, I have the energy take LCR which I think have dual 4 inch woofers and a tweeter, directly behind the listening area.

I don’t have enough budget “yet – since I am upgrading the sub amplifier” to build anything I like, but I was contemplating a DIY of two MTM-like towers for the front speakers. I was considering the full range drivers, mainly the mark audio ones alpair 12p (connected in series at 16 ohm), Dayton full range 8 inch, tang band, and just today I have stumbled upon the Fender 8" Full-Range (extended range) sold really cheap on parts-express at around 15 dollars. And having a low budget and knowing that I need a carpenter to help me do the wood work for a fee of course. I thought of these fender speakers, is there a way to build a project around them (are they worth it), I was thinking but as a novice to have 4 of these and a tweeter in one ported or even sealed tower with some kind of simple crossover. My amplifier is the SC-07 from pioneer that can deliver around 140 watts into 8 ohms. So if I connect two of them in series and then in parallel, I will get 4 speakers per tower that are 8 ohm, and need around 160 watts rms, in addition to a tweeter. I know these are not in the same league as the mark audio or the full rangers from Dayton and tangband. But the price seems appealing, and the SC-07 has a calibration mechanism (each speaker will be equalized) that can give a good edge for even non-so-much linear speakers.

Can anyone give some input regarding what I have said. I am mainly using this for home theater, and sometimes but rarely some music. Will any of the MTM like options above give me a much better performance and quality than my current front speaker setup, taking that below 80 Hz is mainly handled by the subwoofer, but I don’t mind helping the sub with some dynamic bass from the front speakers as well.
 
frugal-phile™
Joined 2001
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The Fender is aimed at guitar amps.

As to Alpair 12, i'd think for anMTM you use the FR as the mid-tweeter, lots of decent woofers you can use below it.

We've done a couple MTM that turned out well. A tallish ML-TL with Mark Audio EL166 and Fostex FF85k, and a standmount with Silver Flute W14 & FF85wk. We also did afantastic TMM with Mark Audio Alpair 7.3 & CSS SDX7. The alternate caninet was an MTM floorstander.

Pick a good 3 or 4" full-range (there are quite a few) and add 2 6.5 to 8" woofers (also lots of choices).

Trying to do a passive XO will restritct the possiblecombinations.

dave

dave
 
Thanks Dave for the information.

I agree that there are better alternatives, Mark Audio one of them. I dont feel (just a feeling) that a single 4 inch full range even coupled with some woofers will satisfy my needs or at least my expectations, but that is just me thinking loudly. My current speakers have 2x4.5 inch mid range woofers (seem similar to the 2 other 4.5 inch woofers used as woofers) and seem to be giving acceptable output, I am sure the alpairs are better, but exchanging these 2x4.5 mid range woofers and tweeter with one fullrange of 4 inch even in a more refined box might not give me the presence that I am looking for at 10 meters from the listening area; but I am not the expert on this.

However, as You started, I was considering and MTM formed of 2 alpair 12 and a tweeter. the alpairs connected in series at 16ohm and a simple high pass filter to the tweeter. in a box that is ported and simple to build like an ML-TL as you have suggested. the higher efficiency of the drivers, and using two of them, in addition to a tweeter seemed to me like a good combination to deliver some good results. and then the subwoofer below 80 HZ can manage the rest.

If I had enough budget I would have gone that way. But since I have seen the fender being sold at much lower then its original price, and seeing that it can deliver a frequency response from 41 to 7 KHz, I "supposed" that with proper equalization from my receiver and a good tweeter working from 5-6Khz till 20-22 Khz, I might have a winner cost effective performing solution for 85% HT and like 15% music. From your words, I felt that this might not be true. and then I might need to wait and invest with a larger budget.

I didnt know that the alpair 12 can be enough as a midrange/tweeter without a dedicated tweeter!
 
Just to add something on my previous message, I am not saying that a 4 inch FR driver with added woofers wont be better overall then my current setup but I was more talking about the mid range presence, not the overall presence.

By the way, I find the designs on Frugal-phile DIY Audio Community Site very helpfull, I like the pencil series due to their simplicity. and the Thirlmere Bipole MBVR for 2 x CSS EL70 design seems good for HT if I am not mistaken (the aesthetic might be good for a saloon/HT). A pencil like design for two alpair 12 with a tweeter would be something relatively good for me as an initial build. BUt the footprint is somehow on the large side.
 
Note that "Pensil" is the name of a format of MLTL enclosures by Scott Lindgren that can certainly be modeled for any Mark Audio driver , but to date I'm only aware of designs in that series for a single driver per enclosure.


As Dave noted, smaller FR (3-4") can excel as mid-tweeter in MTM designs, whether standmount or floorstander. By reducing excursion with crossovers in the region between 160 - 320Hz or so, you can gain substantial improvements in attainable SPLs and dynamic impact in the midrange. We've had great results with 3 different designs using the FF85K and WK in such arrangements, as well as the TMM with Alpair7 and dual SDX7s.


An MTM with dual Alpair12ps would not be a tiny box, and while it's a wonderful driver, to be honest there are smaller drivers - both in Mark's own line, and by others -that dig as deep or deeper, and particularly so in more user friendly sized enclosures.
 
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Thanks Chris for the info, I need to read a lot of material.

One of the things that has driven me to full range speakers, is the fact that I don't want to get into complicated crossovers. Although sometimes as seen, some filters are needed. I saw the fender 8 inch woofer being advertised as going from 40+hz to 7000, and the price is around 12 USD, that seemed cheap for me to start a first build as tower speakers, I thought 4 drivers in a sealed box with a tweeter would give me something to play with. My first build was a subwoofer. still working the amplifier of that one as mentioned.

I wasn't planning for a large budget at this time. I was looking at parts express, and found that for example two 4ohm Dayton 8 inch reference woofers connected in series and crossovered with a morel or Dayton tweeter that has an input of around 200 watts max can be compatible in an MTM setup with a simple crossover from the site with cross over frequency at around 1600 to 2000 Hz. I know not a perfect designed speaker but might fit the job for a first DIY.

I recall few years ago, I came to this site, and I was really amazed by the work done here, and you at that time with Dave helped in answering some of my questions, and this eventually led me to the subwoofer build.

I thought of the Dayton and morel tweeter for the reason that I "thought" that it is better to crossover drivers of the same power range!

How do you crossover an alpair 7 for example of 20 watts to a woofer of 100 or 200 watts, isn't there a risk of burning the little driver at certain power. I know basic question, but I am not familiar with those concepts yet.

As you said, the alpair 12s will need large enclosures, and after looking at my space yesterday and WAF, 30x30x120cm or 30x30x140 would be pushing the limit of an enclosure that would fit the décor.

one other question would be regarding the SPLs that the lower power rater full range drivers can output, like the alpair 7 to alpair 10? as I have never heard these, this makes my choices difficult from far away. As I only have a chance to buy these when I travel to the US. and not all stores accept international credit cards. amazon selling part express drivers is a good one for me.

I was wondering if there are enclosure designs that are straight forward for dual alpair 10s, whether front drivers or opposing drivers.

a lot of questions, that is why I am going to try to do more research. one crazy idea that came to my mind since I am somehow happy with the high frequency output of my current Take towers, is if I can crossover them with a multiple woofer cabinet!
 
I would say the same (power vs. sensitivity).
Relating to the drivers project/make and models to many considerations for the time being.
goldorak,
I would not feed 200W to a tweeter and some of them have that max power capability (note: only use HF with a crossover, be careful with the frequencies you send to the mid/tweeter). As in the same way some woofers have a max. power of 35W or 40W (like some vintages) so you need to be careful not exceeding its maximum power. You can add a modern/high power tweeter but you need to respect the max power of 40/50W (woofer in this case) because each driver of your final project is going to receive a percentage only of the total power (RMS), being the LF or woofer receiving the most in relation also to all crossovers frequencies. Usually the mid and tweeter (HF) receive less energy and should only work with a crossover. After a few projects you get used to it if not using a software or SPICE.
 
I have to agree with both of you (Dave and Inductor). I unrderstood what Dave meant by that power rating are "meaningless" (when the system is operated diligently maybe). So as well care should be taken during operation. You can feel that you have driven the speaker beyond its mechanical limits for example, that would be as well an indication that the electrical limits might have been reached as well. So if I put a 20 watts tweeter with a 300 watts woofer, and my amplifier gain was put in a way to be able to deliver the right voltage to drive the woofer at 300 watts, then if a certain high frequency note came in with the same voltage, that might put the tweeter into danger. for example I was thinking of two dayton woofers that are around 160 watts of maximum power together, if I put as midrange the alpair 10 of 30 watts rms possibly 60 watts maximum power, I am not sure if it might be in danger with a 140 watts rms amplifier!
 
Hey guys, as mentioned in my first post, I am thinking of a project where the benefit/cost is high.

If I get 4 of the fender 8 inch speakers connected in a way to give 8 ohms, then if each speaker has a sensitivity of 88 db, I suspect the 4 speakers at 8 ohm will have a sensitivity of 94db! and I I couple them to the Dayton Audio PT2C-8 Planar Tweeter (sensitivity 94db) at a frequency of 3500 Hz or 5000 Hz? and put them in sealed well stuffed box of 120-130cm height and more or less a 30x30 cm width and depth, will that be a good starting 2 front speakers for Home theatre mainly and some music? the price is very appealing for all of these parts and the possible outcome. Around USD 300 for the drivers and crossover.

The other alternative would have been a 3 way speaker with 2x 4 ohm dayton 8 inch reference woofers per side connected in series (sensitivity 89 db) and 2 Celestion Neodymium 5" Full-Range Woofer 4 Ohm connected in series (sensitivity 89db) and a good priced tweeter at 89 db as well and a 3 way crossover of maybe 800Hz, 4500Hz. trying to get everything as simple as possible already assembled from parts-express.

Any thoughts on both ideas taken that price is of importance, and as well overall SPL and simplicity of the project.

is there a drawback taken that I will keep the energy rear and center for now. I will equalize all channels with the pioneer SC-07 maccac?
 
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What do you mean?!
already assembled from parts-express
You will get what you get if not following any kit/plan. Is just coming from your mind, and you want it to work but that is not enough. there's no simulation no nothing. Is just a plan... or nothing, an idea.
For the time being just follow/buy a kit. Or suffer the consequences.
I'm here not to scare you, just helping if I see where you need help.
 
for the already assembled question, I meant that I will get ready made crossovers.

As for the no simulation thing, you are right, I am not using any simulation program. I just matched the sensitivity and made some rough estimations taking the reviews for the drivers, the impedance matching, and the frequency ranges. My main concern was the price of the drivers in order to do a "scratch" but yet hopefully working project. It does seem that these drivers together (option one or two) "seem" to be going to work fine. what kind of simulation can I do? Moreover, when/ If I was going to build the real box especially for option 2, I was going to use the WinISD program for the box sizes, was going to make it ported for the woofers and sealed for the mid range drivers! this is a first speaker project other then the subwoofer one that I did earlier. I have to start somewhere. I don't have a shop for good drivers where I live, so with the little time that I am going to visit the states, I thought I can get few drivers to play with, as intelligently as possible with some guidance from here.

for the kits, most kits will not be better then my current speakers. at least the 300 dollars kits.

The other alternative that I might be interested in, is if I can find a slim box tower design for two alpair 10s connected in series in each front speaker, something similar to the ML-TL [FONT=Skia-Regular_Regular][FONT=Skia-Regular_Regular]for Mark Audio Alpair[/FONT][/FONT][FONT=Skia-Regular_Regular][FONT=Skia-Regular_Regular]10/10.2
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[/FONT][FONT=Skia-Regular_Regular][FONT=Skia-Regular_Regular][FONT=Skia-Regular_Regular]designed by Jim Griffin.
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