CallingAugerpro (Brandon) Powered Noobster MTM?

mayhem13 · 16th January 2009, 01:24 AM

Hey Brandon, my Son is heading off to 2nd semester and needs some speakers for his PC we built over the winter break. Mostly for movies and music with a little gaming. Was thinking of your Noobster MTM design with the new PE monitor amp

http://www.parts-express.com/pe/psho...number=300-774

Would be really convienient for PC use so he could free up some space without an amp/receiver. The efficiency seems like a good match as well. He'll be listening nearfield so it's a toss up between front or rear port in 1 cuft. The Amps just went on sale and considering the cost reduction of no passive components, seems like a no brainer. I'm concerned if i'll need to add a passive notch or if the 3k xo 24db/oct will get it done on it's own.

mayhem13 · 17th January 2009, 01:06 AM

A polite Bump.

Jay_WJ · 17th January 2009, 02:21 AM

I'm not Brandon, but I think I can comment on this. If you use the active crossovers of the plate amp, the speakers will have nothing to do with Brandon's design except only the choice of drivers.

And you can't expect good driver summation from the use of active crossovers with predetermined slopes, due to the drivers' natural rolloffs.

I have modeled quite a few crossovers for the W5-704D in MTM for people here and over at the PE Tech Talk board. I can quickly model a crossover with the PE plate amp if you ask me. You'll definitely need additional (not many, though) passive components to achieve good crossover performance.

If you want high efficiency, a single TB W6-789S in MT is a good option, too. What tweeter do you want to use? The Vifa DX25?

-jAy

mayhem13 · 17th January 2009, 02:46 AM

Thanx Jay and yes the DX25. I know he's going to drive them to their limits so hopefully the high efficiency will give him enough output without doing it too often. If the component count isn't too high, i'd certainly appreciate the effort. What first attracted me to Brandons design and the plate amps is the abilty of the 704 to play up to 3k nicely. I could just scratch the plate amps and give him my Onkyo M-282 but something tells me with a few components this is going to sound really really good.

Jay_WJ · 17th January 2009, 02:49 AM

Did you already purchase the drivers?

Oh, one more thing. Where will the speakers be placed?

mayhem13 · 17th January 2009, 03:27 AM

I've got the 704s, but not the Vifas. They'll be nearfield about 40" apart and 30" from the listener. Basically on either side of a 32" monitor at a workstation. In an MTM design, the tweeters would be at ear level. A sub probobly wouldn't work in a dorm room so if i can avoid one and having to pay for an off campus apartment down the road......LOL.

Jay_WJ · 17th January 2009, 01:56 PM

Being crossed at 3 kHz with a higher order filter, the DX25 is an overkill. The Dayton ND20FB-4 or ND20FA-6 will be perfect in this application. Plus, they have no higher (even slightly lower) tall order distortion than the DX25 above 3 kHz. Also, if the speakers are near-field, they will be very sensitive to the slight change of the listener's ear level due to MTM lobing errors with the 3 kHz xover point. Close driver spacing with the Dayton neo will help here. If you still want the DX25, I can model up the xover with it, though.

mayhem13 · 18th January 2009, 02:20 AM

The Dayton ND20FB-4 looks like a real money saver here so thanx for the recommendation. If you wouldn't mind setting me up with a passive network that'll work with the plate amp, i'd greatly appreciate it. Thanx in advance.

mayhem13 · 18th January 2009, 03:34 AM

I was also wondering if mounting this tweeter in a shallow waveguide as a continuation of the existing housing would help with the two peaks in the F5 at 2.1 and 2.7khz. I'm under the impression that the tweeter will operate a bit more efficiently but would need a cap to shape the freq response back to flat. Would the results be worth the effort with such an inexpensive build. I have a lathe and lathe operating experience if that helps. I've done a few cutting tests with MDF circles in the past and had good results. I'm suggesting something small, maybe 2.5" in diameter as not to increase the D to D spacing.

Jay_WJ · 18th January 2009, 03:41 AM

Wave guide experiment will be interesting and may be worth the effort in some other design. But in our case, the crossover will be acoustic LR6 so distortion below 3 kHz will be a non issue. Also, the WG will change the response, and modeing it will be out of the question.

16th January 2009, 01:24 AM	#1
mayhem13 diyAudio Member Join Date: Sep 2008	CallingAugerpro (Brandon) Powered Noobster MTM? Hey Brandon, my Son is heading off to 2nd semester and needs some speakers for his PC we built over the winter break. Mostly for movies and music with a little gaming. Was thinking of your Noobster MTM design with the new PE monitor amp http://www.parts-express.com/pe/psho...number=300-774 Would be really convienient for PC use so he could free up some space without an amp/receiver. The efficiency seems like a good match as well. He'll be listening nearfield so it's a toss up between front or rear port in 1 cuft. The Amps just went on sale and considering the cost reduction of no passive components, seems like a no brainer. I'm concerned if i'll need to add a passive notch or if the 3k xo 24db/oct will get it done on it's own.

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17th January 2009, 01:06 AM	#2
mayhem13 diyAudio Member Join Date: Sep 2008	A polite Bump.

17th January 2009, 02:21 AM	#3
Jay_WJ diyAudio Member Join Date: Mar 2006 Location: Indiana	I'm not Brandon, but I think I can comment on this. If you use the active crossovers of the plate amp, the speakers will have nothing to do with Brandon's design except only the choice of drivers. And you can't expect good driver summation from the use of active crossovers with predetermined slopes, due to the drivers' natural rolloffs. I have modeled quite a few crossovers for the W5-704D in MTM for people here and over at the PE Tech Talk board. I can quickly model a crossover with the PE plate amp if you ask me. You'll definitely need additional (not many, though) passive components to achieve good crossover performance. If you want high efficiency, a single TB W6-789S in MT is a good option, too. What tweeter do you want to use? The Vifa DX25? -jAy

17th January 2009, 02:46 AM	#4
mayhem13 diyAudio Member Join Date: Sep 2008	Thanx Jay and yes the DX25. I know he's going to drive them to their limits so hopefully the high efficiency will give him enough output without doing it too often. If the component count isn't too high, i'd certainly appreciate the effort. What first attracted me to Brandons design and the plate amps is the abilty of the 704 to play up to 3k nicely. I could just scratch the plate amps and give him my Onkyo M-282 but something tells me with a few components this is going to sound really really good.

17th January 2009, 02:49 AM	#5
Jay_WJ diyAudio Member Join Date: Mar 2006 Location: Indiana	Did you already purchase the drivers? Oh, one more thing. Where will the speakers be placed?

17th January 2009, 03:27 AM	#6
mayhem13 diyAudio Member Join Date: Sep 2008	I've got the 704s, but not the Vifas. They'll be nearfield about 40" apart and 30" from the listener. Basically on either side of a 32" monitor at a workstation. In an MTM design, the tweeters would be at ear level. A sub probobly wouldn't work in a dorm room so if i can avoid one and having to pay for an off campus apartment down the road......LOL.

17th January 2009, 01:56 PM	#7
Jay_WJ diyAudio Member Join Date: Mar 2006 Location: Indiana	Being crossed at 3 kHz with a higher order filter, the DX25 is an overkill. The Dayton ND20FB-4 or ND20FA-6 will be perfect in this application. Plus, they have no higher (even slightly lower) tall order distortion than the DX25 above 3 kHz. Also, if the speakers are near-field, they will be very sensitive to the slight change of the listener's ear level due to MTM lobing errors with the 3 kHz xover point. Close driver spacing with the Dayton neo will help here. If you still want the DX25, I can model up the xover with it, though.

18th January 2009, 02:20 AM	#8
mayhem13 diyAudio Member Join Date: Sep 2008	The Dayton ND20FB-4 looks like a real money saver here so thanx for the recommendation. If you wouldn't mind setting me up with a passive network that'll work with the plate amp, i'd greatly appreciate it. Thanx in advance.

18th January 2009, 03:34 AM	#9
mayhem13 diyAudio Member Join Date: Sep 2008	I was also wondering if mounting this tweeter in a shallow waveguide as a continuation of the existing housing would help with the two peaks in the F5 at 2.1 and 2.7khz. I'm under the impression that the tweeter will operate a bit more efficiently but would need a cap to shape the freq response back to flat. Would the results be worth the effort with such an inexpensive build. I have a lathe and lathe operating experience if that helps. I've done a few cutting tests with MDF circles in the past and had good results. I'm suggesting something small, maybe 2.5" in diameter as not to increase the D to D spacing.

18th January 2009, 03:41 AM	#10
Jay_WJ diyAudio Member Join Date: Mar 2006 Location: Indiana	Wave guide experiment will be interesting and may be worth the effort in some other design. But in our case, the crossover will be acoustic LR6 so distortion below 3 kHz will be a non issue. Also, the WG will change the response, and modeing it will be out of the question.

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