Javs' Rear Speaker Project - Faital 8PR200 & Beyma TPL-150H - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 154 Old 03-06-2016, 05:50 PM - Thread Starter
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Javs' Rear Speaker Project - Faital 8PR200 & Beyma TPL-150H

***EDIT***

Here is the final product! Ended up with MTM config, 1250hz crossover 12db/oct.




















-------------Thread Start-------------

Hey Guys,

Well my front sound stage build is all done and wrapped now... Been listening to them for the past month or so in bliss. Everything sounds great... Except they make my non pro-audio rear speakers sound like crap.

SO, in the interest of timberal matching, and feeding the DIY bug I am about to begin my build for the 4x rear speakers to complete the 7 channel sound bed. So I will have TPL-150H AMT Tweeters all around me.

This is also going to act not only as my rear speaker but also as a prototype build to perhaps look at selling these as a kit or offer them as finished speakers locally here in Australia. Other people would probably consider these very useful for a main sound stage. But with my mains, these should compliment very nicely.

I am going for two way. Dual 8inch Faital 8PR200 woofers, and the TPL-150H AMT.

1800hz crossover point. 8ohm nominal. 98db/Watt Sensitivity.

Spec Sheets:

http://www.usspeaker.com/beyma%20tpl150h-1.htm

http://www.faitalpro.com/en/products...p?id=101030200


Here is the design I have arrived at and the dimensions. I am looking at a box which has a 3db rolloff of 50hz. Flat to 80hz.

Everything will be cut on a CNC machine. I have designed it so it should be easy to cut more and what boxes together in minimal time with good strength. 25mm MDF throughout. These ones are just going to be sprayed with Duratex but hopefully the finish and texture will come out quite nice. I really like how the baffles turned out on my L/C/R speakers with the sprayed finish.



More to come soon! I will try to document this build a little better than my last one.

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post #2 of 154 Old 03-07-2016, 08:09 PM
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I'll be watching intently. Are you planning to remove the backplate?
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post #3 of 154 Old 03-07-2016, 08:50 PM
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The crossover would be too high due to the center-to-center distance of the 8's
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post #4 of 154 Old 03-07-2016, 09:02 PM
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Great choice of components. I was looking at doing the same setup but was unable to get the 8's so that went out the door. Look forward to how this progresses.
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post #5 of 154 Old 03-07-2016, 09:05 PM - Thread Starter
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Quote:
Originally Posted by SpinMonster View Post
The crossover would be too high due to the center-to-center distance of the 8's

You're right. How far off am I? On my phone at the moment Ill check the maths when I get home.

I could run the AMT as low as 1400/1500... Ive heard it and its fine. If I did that I could make a little chamber for it and take the back plate off. From what I read there is a little resonance which originated from the backplate if you crossover too low.

Failing that Ill look at 2.5 way and loose a little sensitivity.

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post #6 of 154 Old 03-08-2016, 03:13 AM - Thread Starter
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So I am thinking I will move forward with a 2.5 way scenario.

Is there any reason to think the current box design will not work well with a 2.5 way?

The 8 which will become the LF/Mid combo I am thinking will go above the AMT.

Thats somewhat similar to my current LCR speakers, the mid is on top.

Failing that, I could do it this way, though I am not super fond of the 'visual' aspect of this design. If the two designs would yield a pretty similar response with no adverse effects I will go with the design I posted originally.

I am guessing the below design would yield a bit more of an airy treble range to it.

This is for HT application though so I am kind thinking the mid on top to match my larger speakers will 'sound' more like a match.

Thoughts?


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post #7 of 154 Old 03-08-2016, 09:15 PM
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I had thought about a dual 8" system but went with a single 10", the TD10M and love it. I also didn't have to deal with crossing the lower unit at a different frequency that an upper 8. The TD10M is really efficient. It is a 4 ohm unit. I have active crossovers.

This is the thread from DIYaudio. The 8 you are looking to use go very mixed feedback for me. I hope this helps.

http://www.diyaudio.com/forums/multi...ms-4550-a.html
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post #8 of 154 Old 03-08-2016, 09:52 PM - Thread Starter
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Javs' Rear Speaker Project - Faital 8PR200 & Beyma TPL-150H

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Originally Posted by SpinMonster View Post
I had thought about a dual 8" system but went with a single 10", the TD10M and love it. I also didn't have to deal with crossing the lower unit at a different frequency that an upper 8. The TD10M is really efficient. It is a 4 ohm unit. I have active crossovers.



This is the thread from DIYaudio. The 8 you are looking to use go very mixed feedback for me. I hope this helps.



http://www.diyaudio.com/forums/multi...ms-4550-a.html

Thanks

I wont use that brand its too expensive for me in Australia especially considering the prices I get from Beyma and Faital direct.

Already have all the drivers in hand.

I sent the top design off the the CNC shop.

Going with 2.5 way.

Ill update with box building and measurements.

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post #9 of 154 Old 03-08-2016, 11:39 PM
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Can you consider a single fold MLTL tuning for the woofers, that may help extend the LF corner and make these full range speakers for 2 channel setup?

Sent from my GT-I9505 using Tapatalk
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post #10 of 154 Old 03-09-2016, 12:05 AM - Thread Starter
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Can you consider a single fold MLTL tuning for the woofers, that may help extend the LF corner and make these full range speakers for 2 channel setup?

Sent from my GT-I9505 using Tapatalk
I would totally consider that if I made this into a taller tower speaker which I almost did. Its more an extreme bookshelf speaker haha.

This is I guess 90% for my own needs obviously and 10% prototyping for possible set ups to offer to people in Australia if I get it right.

I definitely did not want towers for rears. A taller version with the lower woofer having a bit more cabinet area to work with would be a great idea for another variation on this config. The fs on this driver is 70hz though, so not sure how well it would do in a full range configuration.

The concept was make a speaker which would be great to 60/80hz crossover in a HT environment and hopefully great for music too.

As they are now, they will be 50hz -3db point and 40hz at -8db.

So I guess with a little EQ like Audyssey or something you would theoretically get them flat to 40hz if you wanted. Though I would recommend a pretty good roll off at 50hz as cone travel starts flying up under the tuning freq and you run out of xmax at 45hz if you fed them 400watts RMS (2 woofers).

100Watts of power would see that problem go away though and you would be fine for displacement at any freq. 100 watts would net you 115db though so that's more or less reference anyway.
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post #11 of 154 Old 03-11-2016, 08:35 AM
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Hi!
what are the avantages of putting 2 x 8 inches woofers vs only 1??? and why replacing them with 1x 10 inches instead of 2?? thanks! cheers
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post #12 of 154 Old 03-11-2016, 09:06 AM
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Quote:
Originally Posted by SpinMonster View Post
The crossover would be too high due to the center-to-center distance of the 8's
I'm interested into having more infomration about how do you arrive to this conclusion, can you please explain it a bit?

thanks
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post #13 of 154 Old 03-11-2016, 09:08 AM
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Quote:
Originally Posted by Javs View Post
You're right. How far off am I? On my phone at the moment Ill check the maths when I get home.

I could run the AMT as low as 1400/1500... Ive heard it and its fine. If I did that I could make a little chamber for it and take the back plate off. From what I read there is a little resonance which originated from the backplate if you crossover too low.

Failing that Ill look at 2.5 way and loose a little sensitivity.
How is that sensibility calculated passing from a 2 way to a 2.5 way? thanks
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post #14 of 154 Old 03-11-2016, 03:35 PM - Thread Starter
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Originally Posted by rggomez View Post
How is that sensibility calculated passing from a 2 way to a 2.5 way? thanks

It would actually be the same sensitivity in theory doing 2.5 way as the .5 way woofer will essentially over come the baffle step loss.

Here is an example (not my crossover)

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post #15 of 154 Old 03-11-2016, 03:39 PM - Thread Starter
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Javs' Rear Speaker Project - Faital 8PR200 & Beyma TPL-150H

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Originally Posted by rggomez View Post
I'm interested into having more infomration about how do you arrive to this conclusion, can you please explain it a bit?



thanks

For MTM to work properly and not have some high amount of lobing issues the center to center distance from the woofers needs to be as short as possible. One half wavelength is preferred. One wavelength is ok but not optimal.

But my design if I were to use two way MTM as pointed out by a forum member would have been too spread out and would actually be over two wavelengths in distance from each other at the crossover freq.

2.5 way gets around the lobing as one woofer is tapering off earlier than the other and by the time you hit the crossover freq to the tweeter the first bass woofer is almost gone completely. See reply above for what that looks like.

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post #16 of 154 Old 03-11-2016, 03:43 PM - Thread Starter
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Javs' Rear Speaker Project - Faital 8PR200 & Beyma TPL-150H

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Originally Posted by rggomez View Post
Hi!

what are the avantages of putting 2 x 8 inches woofers vs only 1??? and why replacing them with 1x 10 inches instead of 2?? thanks! cheers

Personally I wanted 2 8inch drivers, that was a design choice. Simple as that. I am not a huge fan of single woofer speakers visually.

I already have the drivers in hand so I am not interested in peoples suggestions on others as I already did some research and am wanting to try out the 8 inch Faitals. They are supposed to be great units.

10 inch drivers add width to the speaker which I was not interested in doing not to mention extra cost.

One reason I chose two is because the Beyma AMT sensitivity is 102db/watt.

One 8 inch driver is 95db. You have two and its 98db/watt in sensitivity so its a closer match to my design goal of making a speaker as close to 100db/watt as possible to match my mains which are already 100db/watt.
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post #17 of 154 Old 03-12-2016, 02:00 AM
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Quote:
Originally Posted by Javs View Post
Personally I wanted 2 8inch drivers, that was a design choice. Simple as that. I am not a huge fan of single woofer speakers visually.

I already have the drivers in hand so I am not interested in peoples suggestions on others as I already did some research and am wanting to try out the 8 inch Faitals. They are supposed to be great units.

10 inch drivers add width to the speaker which I was not interested in doing not to mention extra cost.

One reason I chose two is because the Beyma AMT sensitivity is 102db/watt.

One 8 inch driver is 95db. You have two and its 98db/watt in sensitivity so its a closer match to my design goal of making a speaker as close to 100db/watt as possible to match my mains which are already 100db/watt.
Many thansk for the answers...what soft are you using to simulate the speakers?
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post #18 of 154 Old 03-12-2016, 04:45 AM - Thread Starter
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Many thansk for the answers...what soft are you using to simulate the speakers?
Bassbox Pro for ideas and box modelling before building. OmniMic to measure when box is built, SoundEasy to model crossover and simulate/tweak.

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post #19 of 154 Old 03-12-2016, 04:58 AM
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Bassbox Pro for ideas and box modelling before building. OmniMic to measure when box is built, SoundEasy to model crossover and simulate/tweak.
Sweet!! thanks
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post #20 of 154 Old 03-12-2016, 06:32 AM
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Quote:
Originally Posted by rggomez View Post
I'm interested into having more information about how do you arrive to this conclusion, can you please explain it a bit?

thanks
The rule of thumb is to not exceed a 1-wavelength center-to-center driver spacing at the crossover frequency. When two drivers make the same frequency you divide 13560 by the number of inches between them. If the center to center distance of two 8" drivers with an 8" tweeter between them is 17" then 13560/17 = 800hz for a decent crossover. That's too low for that AMT. For a 2.5 system using those drivers, 13560/9 would yield a 1500hz cross to the tweeter and 340hz or so is where you can roll out the lower 8" assuming a 38" center tweeter height.
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post #21 of 154 Old 03-12-2016, 06:57 AM
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Quote:
Originally Posted by SpinMonster View Post
The rule of thumb is to not exceed a 1-wavelength center-to-center driver spacing at the crossover frequency. When two drivers make the same frequency you divide 13560 by the number of inches between them. If the center to center distance of two 8" drivers with an 8" tweeter between them is 17" then 13560/17 = 800hz for a decent crossover. That's too low for that AMT. For a 2.5 system using those drivers, 13560/9 would yield a 1500hz cross to the tweeter and 340hz or so is where you can roll out the lower 8" assuming a 38" center tweeter height.
great, thanks for the explanation...and the 340hz, where this come from?? We're assuming a MTM config right?
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great, thanks for the explanation...and the 340hz, where this come from?? We're assuming a MTM config right?
No, I said the lower woofer in the 2.5 is crossed at 340hz to phase it out sooner than the upper 8".
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post #23 of 154 Old 03-12-2016, 04:37 PM - Thread Starter
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No, I said the lower woofer in the 2.5 is crossed at 340hz to phase it out sooner than the upper 8".
I think he is asking how you arrived at 340hz estimation as it seems pretty random but precise like you calculated it somehow. I am interested to know how you arrived at that too.

I was likely going to look at starting the roll off at 350 or 500hz and see what it sounds like. Whatever gives me a clean flat reinforcement to the crossover freq. My mains roll off at 350hz so that would be the best bet I think.

Center of tweeter at 38"? What is that.

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post #24 of 154 Old 03-12-2016, 04:41 PM
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Quote:
Originally Posted by Javs View Post
I think he is asking how you arrived at 340hz estimation as it seems pretty random but precise like you calculated it somehow. I am interested to know how you arrived at that too.

I was likely going to look at starting the roll off at 350 or 500hz and see what it sounds like. Whatever gives me a clean flat reinforcement to the crossover freq. My mains roll off at 350hz so that would be the best bet I think.

Center of tweeter at 38"? What is that.
exactly Javs, that was my question...And actually sorry for so many questions but why /17 and afterwards so divide by 9 ? is because the 2.5 config is with not a MTM?? if so, it is possible a MTM config with 2.5?
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post #25 of 154 Old 03-12-2016, 04:42 PM - Thread Starter
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exactly Javs, that was my question...And actually sorry for so many questions but why /17 and afterwards so divide by 9 ? is because the 2.5 config is with not a MTM?? if so, it is possible a MTM config with 2.5?
Technically it is an MTM 2.5 way.

It is NOT however a D'Appolito configuration anymore.

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post #26 of 154 Old 03-12-2016, 05:20 PM
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Quote:
Originally Posted by Javs View Post
I think he is asking how you arrived at 340hz estimation as it seems pretty random but precise like you calculated it somehow. I am interested to know how you arrived at that too.

I was likely going to look at starting the roll off at 350 or 500hz and see what it sounds like. Whatever gives me a clean flat reinforcement to the crossover freq. My mains roll off at 350hz so that would be the best bet I think.

Center of tweeter at 38"? What is that.
38" is the tweeter listening height to verify MTM vs TMM for the lower woofer height from the floor.

You use a baffle step calculator for the lower woofer cross freq. A 2.5 way uses an earlier roll out of the lower woofer or you get a smeared imaging effect. It is actually 365hz for a 12" wide baffle.

http://diyaudioprojects.com/Technica...it-Calculator/

Judging from the questions, I recommend that the OP use an existing kit rather than try to build this difficult system as a first DIY from scratch.
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post #27 of 154 Old 03-12-2016, 05:30 PM - Thread Starter
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You use a baffle step calculator for the lower woofer cross freq. A 2.5 way uses an earlier roll out of the lower woofer or you get a smeared imaging effect.

Yep I know this, I have looked into it recently.

Judging from the questions, I recommend that the OP use an existing kit rather than try to build this difficult system as a first DIY from scratch.

Nope I wont use an existing kit and I never will. This is not my first build it's my fifth. Check out the 3-way I just built in my sig. A 2.5 way is something I have never done before is all. You don't have to answer the questions if you don't want to mate, but I believe in jumping in and having a go and learning on the way. If the whole world made kits instead of designing something new we would never learn a damn thing.

The problem is when you throw out figures without explaining what they mean as you go some people don't understand what you are talking about. Just because I don't have the math theory readily available in my head to recognise the figures you are quoting and arriving at has absolutely no bearing on my ability to build speakers. Its even tougher when you are quoting imperial units... I am Australian and most of the world does not deal in imperial units. Your speed of sound calcs are confusing for eg as a result. So I use calculators for most of that stuff.

Thanks for chiming in anyway.
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post #28 of 154 Old 03-12-2016, 05:41 PM - Thread Starter
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Considering when I measure my drivers the baffle step is already going to be included in the measurements it will be pretty clear what crossover freq I will need to use for the lower woofer when it comes time to model the crossover.

For some reason this image disappeared when I added it yesterday, it may help others understand how a 2.5 way works... I know it was very informative for me and told me everything I need to know about the interaction between the drivers. Looks like a really great system to me.

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post #29 of 154 Old 03-12-2016, 06:08 PM - Thread Starter
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Quote:
Originally Posted by a|F View Post
I'll be watching intently. Are you planning to remove the backplate?
No. Not planning on it.

My last build with the TPL-150H I did indeed make a chamber for the units and removed the backplate and filled it with absorbing material lining the walls and also poly stuffing inside.

For this one as the name of the game is to be relatively simple in the box build internally and maximise the volume the LF woofers have to work with. Making an internal chamber for the TPL will reduce that and not what I want for a speaker this size. I will do some experimentation with altering the lining materials inside the backplate. From what I have read the backplate distortion has actually come from the plastic plate resonating at certain frequencies, so I might see how I go deadening the rear plate by adding bitumen deadening sheeting to the outside of the unit plate and even the horn and filling the inside of the plate with different types of acoustic absorption material.

The felt pad inside the backplate at the moment is pretty crappy, there is no way that would totally stop any reflections internally so at the very least increasing dramatically the material inside the plate and even stuffing it with some poly may improve quite a bit the distortion figures. I also read that some of this distortion people speak of actually happens lower in the freq range below the ~1800hz crossover freq a lot of people are using. One of the few reasons people now cross it over higher.

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post #30 of 154 Old 03-12-2016, 07:55 PM
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In post 23 you asked:

Quote:
Originally Posted by Javs View Post
I think he is asking how you arrived at 340hz estimation as it seems pretty random but precise like you calculated it somehow. I am interested to know how you arrived at that too.
.
I responded:
You use a baffle step calculator for the lower woofer cross freq. A 2.5 way uses an earlier roll out of the lower woofer or you get a smeared imaging effect.


Then you posted:

Quote:
Originally Posted by Javs View Post
Yep I know this.

Thanks for chiming in anyway.

Good luck with your build.
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