# Natalie P tower build questions



## steve1616

I was wanting to build some Natalie P towers and matching center channel for my mom. I have a question about making the towers. I have seen many people that build a full tower for this platform. They are using the extra box volume to get lower extension. Doesn't this change the crossover needed since the internal volume is changing. I realize that some people just make the Natalie P's look like towers, but they are simply mounting the normal configuration on top of a bottom box to make it look like a tower. There are also people that change the internal volume all together, and actually make a tower out of it. I figure that if I am going to make it look like a tower, I might as well get the extra extension that the extra volume provides. 

Can someone lead me in the right direction to accomplish what I am wanting to know. I mainly just want to know what volume I need to stay at for a tower, and if there needs to be a change in the crossover.

Thanks in advance.


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## fbov

Good choice!
http://www.htguide.com/forum/showthread.php4?t=30536

You've been advised correctly. LF tuning is independent of XO design. I made mine 65l, using the added volume to create an "extended bass shelf" or EBS alignment. This trades mid-bass output for increased bass LF extension, relying on room gain to fill in the lost mid-bass while extending LF even farther. My port tuning is ~23Hz. I'd give you deails, but it's a slotted port, which makes it somewhat unique to my design.  

An EBS alignment is a very good idea if you're only making her an LCR. If there's any chance for a sub, you may want to stick with a smaller, sealed driver volume, regardless the external form factor. You can also model all this yourself. If you have Excel, look for "Unibox," otherwise WinISD.

Also, and this is important, if you plan on a horizontal CC, *DON'T MAKE A THIRD NATP FOR THE CC*. Make this, instead.
http://htguide.com/forum/showpost.php4?p=144234&postcount=1
or if mounted in furniture containing the TV...
http://htguide.com/forum/showpost.php4?p=146516&postcount=30

I've short-shrifted my CC's for years, and just built this version. It's not cheap, but it works much better than any option using wider driver spacing and higher crossover freq. Highly recommended; even the wife noticed. 

Also, any chance she's got a CRT? If so, wait for the shielded drivers, due in early May per PE. If not, the unshielded ones are a direct replacment to the XO, but require some tweaking of the bass alignment. 

Have fun,
Frank


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## steve1616

I saw that the center channel you recommended is the Modula MTM. I think this speaker is around $400. I want to go with the Natalie P's because parts are around $400 for the pair of speakers, and then I would build the boxes. I need to get my mom a 5.1 surround system for $1000 including the sub which I will also build. I do see the problem with the MTM alignment for the center channel. I saw that there is a crossover made to help this problem with the Natalie P's. The crossover is a 2.5 way instead of the normal 2 way. Should I use a 2.5 way for the front 3 or just stay with the original design. I do understand the problems with the MTM alignment for a center channel, but my Mom has never had surround sound so she will be happy as pie with the Nat P's. 

What are you thoughts? Also, thank you for the information on the XO. I didn't realize that box volume had no effect on XO configuration.

Oh, my mom has an LCD so no problems with the non shielded drivers.


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## domwilson

Where are the plans for the original Nat P?


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## steve1616

I can't find the original plans now, but I did find this tonight. http://www.htguide.com/forum/showthread.php4?t=13969 This might be similar to the plans I found before, but I noticed that these plans talk specifically about using a tower version with some very low tuning. It looks like this solves the non linear problems that the RS180 has. The RS180 looks like it can be tuned very low for a 7" woofer. I did notice that the Xmax is very large for this size of woofer. Even though I really wanted to use the peerless nomex woofer because of the great frequency response and low distortion, I am getting excited about building the Nat P.


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## domwilson

I think they use these cabinets... http://www.parts-express.com/pe/showdetl.cfm?Partnumber=302-750


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## domwilson

Here is the plans for the Nat P tower.. http://www.htguide.com/forum/showthread.php4?t=19596


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## steve1616

Thank you very much for the tower plans. I saw that I could buy the cabinets from parts express, but since I need to save money and build the towers anyway, I mights as well build all the boxes. The BOM that I had only showed $308.66 for all of the parts for a pair of towers. I better make sure that is somewhat current.


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## vann_d

yeah, good luck. I think driver prices have increased. Sounds like a cool project. You'll probably want to steal them from your mom when you're done...haha


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## steve1616

I just noticed that Zaph's audio said that there was a consistency issue with the RS28a. Should this concern me or was it an old problem?


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## 1Michael

This center channel would be a better match for the Natp. http://www.eldamar.net/audio/rs150mtm/
and it is cost effective.
I have built his speakers before and can give this designer CJD/JCD the :T


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## fbov

steve1616 said:


> I saw that the center channel you recommended is the Modula MTM. I think this speaker is around $400. I want to go with the Natalie P's because parts are around $400 for the pair of speakers, and then I would build the boxes. I need to get my mom a 5.1 surround system for $1000 including the sub which I will also build. I do see the problem with the MTM alignment for the center channel. I saw that there is a crossover made to help this problem with the Natalie P's. The crossover is a 2.5 way instead of the normal 2 way. Should I use a 2.5 way for the front 3 or just stay with the original design. I do understand the problems with the MTM alignment for a center channel, but my Mom has never had surround sound so she will be happy as pie with the Nat P's....


But only if you have a good CC. 

I've been down this exact road - NatP CC --> 2.5-way CC --> Modula CC - so I offer my experieces. The 2.5-way did what was advertised, but didn't sound as good as the base XO to my ears at that time. The 2.5 XO is also twice the cost of the NatP XO. Granted, Modula doubles the price of the speaker...

Much as I love my NatP's, you might better serve your mother's needs with a different design. NatP's are a "bargain" design from a high-end designer; maybe something smaller and simpler would suffice? If you like the RS-series, the Aviatrix uses ND140 drivers with the RS28... and it's a complete design (MTM, MT and CC). Zaph Audio (John Krutke) sells several kits through Madisound that are in your price range. The ZA-series is a complete design...
http://madisound.com/store/index.php?manufacturers_id=186
... and the SR71 is an MT, but one user worked with Krutke to create an SR71 CC. 
http://techtalk.parts-express.com/showthread.php?t=222069

Yes, there are consistency issues with RS28-series tweeter sensitivity. They are most common when combining drivers purchased years apart (as I did) and the fix is as simple as adding a parallel resistor across the hotter one. Sensitivity is marked, so you know if you should expect to tweak a little. 

I just re-priced things and yes, $400/pair for NatP drivers and XO parts. You see, I want another pair....

Have fun,
Frank


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## steve1616

fbov, I see what you are saying. It would be better to spend the money once and get it right since the center channel is so important. I am very concerned about some things I have read about the RS28. The inconsistency problem is one thing, but I am really concerned about the fact that the tweeter is completely different design from when most of the crossovers were made. The tweeter use to be a fluid cooled design, but now it is not. i haven't seen any new designed crossovers that were made after this tweeter change. The tweeter change is documented on the Zaph audio website.


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## steve1616

Does anyone know if the Natalie P's were ever made with the Seas tweeter? This would make me feel better about it since Zaph's audio has kind of made some bad remarks about QC on the RS28.


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## fbov

Design change? Where'd you get that idea; it's not on Zaph's site. Ferrofluid is not a cooling fluid, it modifies the magnetic field, and it's only one of many ways. It seems Usher found the tweet worked better without it, so removal was an upgrade. 

There were some quality issues discussed when I built my NatP CC in 2008, but they were resolved before then; there's no lack of new designs since them. Aviatrix are one new and popular design, and then there's these, which were tied for best-of-show on my card at InDIYana 2009. My Continuums have the mis-match tweeters I cited above, and they do not disappoint. 
http://www.salksound.com/continuum - home.htm

Have fun,
Frank

PS The Modula series used Dayton RS28a (Aluminum Dome), Seas 27TDFC (Textile dome), or Seas 27TBFC/G (Aluminum Dome) tweeters. NatP uses only RS28A or F.


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## steve1616

I got the idea because supposedly the new tweeter version (without ferrofluid) is suppose to be a little better, which would mean a change in frequency response a little, and wouldn't that change the crossover a little


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## domwilson

Purpose of Ferrofluid... http://www.liquidsresearch.com/documents/lspeaker.pdf


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## 1Michael

There is no longer a tweeter QC issue...The unshielded tweets will work just fine. Don't be skeered:T


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## domwilson

That's what I've been reading as of late. From what I understand, there used to be an inconsistency in the sensitivity of these tweeters. But they seem to have fixed that issue.


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## steve1616

I guess I should get started. The tweeter QC was the only thing that I was afraid of. I think I am going with a Dayton driver for the sub also.


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## steve1616

http://www.eldamar.net/audio/rs150mtm/

Is this the design that CJD was making as a dedicated center channel for the Natalie P's? I remember reading clear back in 2006 that he was going to make a center channel for the Natalie P's.


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## 1Michael

No. He did not design the NatP's. He created this CC to match the various Dayton builds as a budget limited project and it will go nicely with the NatP. You will just have to trust me on this because I have built CJD/JCD's designs before...


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## steve1616

Ok, also. Should I go with the non sheilded dayton RS180 or the shielded version. The shielded version is actually cheaper, but I have heard that non shielded woofers can be better. Would it be wise to go with the shielded because that was what the original design was? For some reason I thought that CJD had his own crossover version for the NAT P's.


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## 1Michael

Follow the plans...


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## steve1616

So I went to put my order in today, and I noticed that it said the shielded RS180's that the build shows are on backorder. I have read that the new unshielded RS180-8 woofers react different to bigger boxes, but I didn't know if it would be ok for a tower of 47.3 liters. The link below is the build that I want to copy.

http://www.htguide.com/forum/showthread.php4?t=19596&page=1&pp=35

Do you think the non shielded rs180 woofers would be ok?


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## fbov

Here's the scoop. 

PE dumped their entire shielded RS line late last year. The unshielded replacements were thoroughly tested by DIY designers them and found to be drop-ins electrically (no XO change), but happier in smaller boxes (bass alignment change). Since things like box size and port length are normal bass tuning knobs, this was not considerd an issue. 

However, PE's been listening. Here's more from them on shielded vs unshielded, and confirmation regarding the RS180S-8 coming back. 
http://techtalk.parts-express.com/showthread.php?p=1717813#post1717813

Here's what Unibox shows as the effect of a drop-in replacement in my 65l, 32 Hz box. At these frequencies, room modes can drive +/- 10dB variations, so this isn't anything to worry about. 
  

I know CJD did an extensive series of RS150-based designs, which would likely play nice with designs based on their bigger brothers. RS180's have design families from Jon Marsh (Modula/NatP) and Jed Kuntz (Clearwave Loudspeakers), plus designs like Statements. In fact, the 180S's in my towers came from Jed; he lives nearby. 

I have an HD CRT, so shielding matters. If you don't, you have a choice. 

Have fun,
Frank


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## domwilson

Here's site that looks like good reading... http://stonessoundstudio.com.au/stone/diy_speaker_info/diy_contents.htm


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## steve1616

*Nat. P build thread, and questions*

I had some spare time today, and decided to start cutting wood for my Nat P. project. I got most of the wood cut, but I had a question on my bracing. I only had a 2.5" hole saw bit so put 4 of those in my brace, and then flared them out with a router. Will this cause any problems with airflow, or is it enough to adequately let air pass by?


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## 1Michael

*Re: Nat. P build thread, and questions*

It is fine. There actually was no need to flare the braces.


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## fbov

My rule of thumb is 50% open space in a window brace. You're well below that, and there's an easy way out, once you understand bracing requirements. 

The objective is to reduce box wall resonance. The most effective place to do that is in the middle of the panel, connecting one side to the other. Dowels are popular for that purpose. A window brace damps in 2 dimensions (side-side and front-back), primarily through the center-center connection (the solid sections that cross in the middle). 

If you cut off the corners, making sort of a Maltese Cross, you can greatly reduce brace area with little reduction in bracing effectivness. What you lose is the benefit of a full-width panel stiffener, not really needed with the short spans this piece will brace. 

Have fun,
Frank


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## steve1616

I hope my bracing is ok because it is glued and screwed. I don't think I will have a problem for my application. Although, I do think a good I beam style brace would be very simple. I also learned that I should get some clamps, and forget about all the screws. I could have done everything in 1/10 of the time if I had clamps instead of screws.


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## steve1616

I was also wondering, does anyone make an arched, rounded top that I could buy. The style I am talking about is the exact same thing that the SVS MTS-02's use on the top of that speaker. I like this look, but have no idea how to make something like that.


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## fbov

Nice start! 

For the top, the best idea is to look into curved cabinet build methodology. MDF will bend if you cut slots (kerfs) most of the way through at regular spacings. but a thin blade and lots of slots are needed to avoid a facetted appearance. Thin (aka bendable) MDF can be bent directly over a form and built up with several layers. Trans-lam method would work, too - cut 3/4" into the desired profile so they stack up to the shape you want, then glue them together, edge-to-edge. 

Or you could ask Ed what he did....
http://techtalk.parts-express.com/showpost.php?p=1720679&postcount=3

Have fun,
Frank


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## steve1616

I think your last idea is kind of what I had in mind. I was thinking about using a router and cutting the arch shape into the 3/4 MDF. If my cabinet is 11" deep, I could cut 8 chunks out, plane the last piece of MDF and glue them from front to back.


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## fbov

The way I'm thinking, you need 11/0.75 or about 15 pieces from 3/4" MDF. I expect that's the way Ed did his Storms. Make a template and have at it!


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## steve1616

I don't know why I said 8 chunks with 3/4 MDF? I was trying to find some 1.5" MDF tonight, and I figured that instead. I couldn't find any, but I did find some 1" MDF that a store wants to get rid of so they said they would sell it to me for $35. I was trying to find some thicker stuff so that I didn't have to make quite as many chunks.


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## steve1616

I have a quick question on the cutouts for the speakers on this cabinet. I have the dimensions for the location of the woofers and tweeter in respect to the front baffle, but I don't know what exact cutout dimensions should be for the woofers. Maybe I should just wait until my woofers arrive, but they got put on backorder, and I have to wait until they come back in stock on the 5th of April. I would like to have all the cutouts done, and the boxes totally finished so that I can just bolt the dayton woofers in when they arrive.


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## domwilson

If you are using the reference series of speakers, you can get the specs. here... http://www.daytonaudio.com/lspeakers/lspeakers_reference.html


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## bambino

Looking good.:T Looking forward to seeing this progress. Nice job.:clap:


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## 1Michael

steve1616 said:


> Maybe I should just wait until my woofers arrive


Always.
Never Cut Holes Without Having Drivers In Your Hand. Or I will be saying "Told you soaddle:".


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## fbov

+1 

Part of measure as many times as you must, to only cut once.


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## steve1616

I will wait until I get the mids to make the cutouts for them. I already have the tweeters so I can get them all done at least. I did learn that I need to add 1/16" extra to the basket dimension of the woofer. I am building a subwoofer for my mom also, and the basket dimension was 10-7/8". I did a cutout of exactly 10-7/8", and the woofer just barely wouldn't fit. I trimmed another 1/16" out of the total diameter and it fit perfect, and still very tight.


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## steve1616

Is there a way to configure the crossover for the Nat P's that would allow me to use biampable speaker terminals? I thought this might be a good idea since my mom will be pushing these speakers with a fairly receiver.


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## 1Michael

I don't see that there would be any benefit to that. They are very good as is.


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## steve1616

I was only worried that my mom's cheap receiver wouldn't handle the speakers. I was just thinking about doing this because that way 2 amps would be handling the load per speaker if it was needed. We still have to buy the receiver yet. We were thinking about the onkyo SR608. I didn't know if it would handle it well. If we bought a refurbished SR707 for the same money I am pretty sure it would handle the speakers fine.


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## domwilson

Are you building your own crossover? If so, just wire the tweeter's crossover to one set of terminals and ther woofer's to the other set. Then you run jumpers between the terminals. + to + and - to -.


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## steve1616

That is the problem. I can't tell what circuitry is distinctly for the tweeter, and what is for the mid woofer.


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## domwilson

Are you building your own crossover or buying a pre-made one? Do you have the schematics for the one you are going to use?


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## steve1616

I am building my own crossover. I have the schematics as shown in the images.


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## domwilson

Looking at this...I'm guessing before C9


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## 1Michael

The Onkyo will work fine...


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## fbov

steve1616 said:


> I was only worried that my mom's cheap receiver wouldn't handle the speakers. I was just thinking about doing this because that way 2 amps would be handling the load per speaker if it was needed. We still have to buy the receiver yet. We were thinking about the onkyo SR608. I didn't know if it would handle it well. If we bought a refurbished SR707 for the same money I am pretty sure it would handle the speakers fine.


+1 on the 707 as that's what I've got running mine. Power issues only occur when you try to pull too much power. With a ~90dB/W sensitivity, I doubt your Mom will have trouble getting loud enough (although I could be wrong). 

NatPs cannot be bi-amped. It's a series/parallel XO design with only 1 input. Note that there are 6 XO designs using these drivers out there, and NatP is the only series/parallel design. However, there's very little to be gained here; more of a marketing feature for the amps than anything audible. 

Have fun,
Frank


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## domwilson

If you want to do a lot of reading... http://www.htguide.com/forum/showthread.php4?t=11321&page=1&pp=35


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## steve1616

I have found the 707 on ebay for 379 refurbished, and 400 new on ebay. The 608 can found for 370 new almost anywhere and it has HDMI 1.4, but that seems to be the only difference that favors the 608. The 707 has multi-eq, and a better amplifier that can handle down to 4 ohms. Would you guys be afraid of a refurbished 707 from accessories for less if I can't get the new one on ebay for a decent price? I am a little scared that there seems to be no shortage of refurbished SR707's. Any thoughts?


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## steve1616

Does anyone know what the port length is suppose to be for the tower build of the Nat. P. The tower build project I am copying never actually states the port length. I am assuming I should tune for around 38 Hz. This is the build I have been copying http://www.htguide.com/forum/showthread.php4?t=19596


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## fbov

Assuming you also built to 47l, as in the link, and are using a 3" port, make it 5" long for 38Hz box tune. 6" will give you 36Hz, 4" more like 40Hz, so precision isn't a requirement. 

These tunings give you something close to flat response to 40Hz with F3s in the 36-37Hz range. In a small room, this may be a little boomy due to room gain. If so, extend the port length by ~2x and you'll have an EBS alignment, with less upper bass, but lower extension, so when room gain is factored in, the result is both flat and deep. Mine are ~65L tuned to 32Hz for just this result. 

Have fun,
Frank


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## steve1616

Thank you very much for the help. I think I will do the suggestion you are saying because of room gain. I am getting very close to being able to listen to these bad boys. They have been a lot of work, but I feel very good about what I have accomplished. I am hoping to post some pictures soon. My busy season just started so the very long work days have slowed my progress recently. I am hoping to coat everything with some laquer based sand and sealer, and then paint it flat black with a touch of rattle can bedliner for a very minimal textured look. I will sand that until it basically just looks like a vinyl wrap.


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## steve1616

I thought I would post some pics of my progress so far. I got one speaker to the point that I could at least listen to it for a little bit. My initial impressions are very good. I have already listened to these against some very expensive competition, and these speakers are as good as any out there. They seem way more lifelike than most speakers. The dayton mids are very responsive and have a tighter punch in the upper bass regions than any speaker I have ever heard before. One thing I really noticed is that these speakers have a clarity in the vocals region that not many speakers can match. 

Some very expensive brands like B&W have a smoothness about them that sounds very good, but not as lifelike as the real material that is being played. Drums sound like drums on the Nat. P. The best way I can describe the Nat P speakers is by saying that they sound like you are listening to the band right in your living room. These speakers would absolutely kill all of the speakers I heard at the high end audio shops that cost well above $2,000. I had my mom come over to listen to what her presents are going to sound like. She just smiled the whole time. She had no idea that these speakers would sound this good, and neither did I.


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## domwilson

Those look great! Can hardly wait to see the end product. Good Job.


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## bambino

Looking great so far, glad to read they sound good too, thats gotta put a big smile on your face. Congrats on the nice build.:T


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## fbov

steve1616 said:


> ...The dayton mids are very responsive and have a tighter punch in the upper bass regions than any speaker I have ever heard before. One thing I really noticed is that these speakers have a clarity in the vocals region that not many speakers can match....
> 
> I had my mom come over to listen to what her presents are going to sound like. She just smiled the whole time. She had no idea that these speakers would sound this good, and neither did I.


The improved transient response was one thing I noticed immediately. Not a bass slam near as much as a tight, high-amplitude wave packet of higher frequencies. 

Vocals I'm still investigating, and not in the tower configuration you built. I used one sideways as my CC, recently (has it been 4 months?) replaced with a purpose-designed center, the Modula MTM CC. The big difference was vocal clarity - dialog instantly became easier to understand. I watched Master and Commander over the weekend, and noticed certain passages were clearly understandable for the first time. I need to investigate, but I need parts to do that....

HAve fun,
Frank


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## steve1616

I am glad I decided to read about placement of coils in a crossover. I was all set to change the layout for my second crossover to make it much cleaner looking and easier to wire, and then I read how different placements can effect the values of the coils. I guess I will just stick to the regular layout.


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## steve1616

I just wanted to post my progress. I took the speaker apart that I listened to and mounted the crossover and ports properly. I have both speakers very close to completion. I designed the crossover so that I could take it out for repair, and I also wanted access to the inside of the speaker. I made my 2 crossovers differently. I soldered the crossover underneath on one and soldered on top on the other. I definitely like the top solder better because it does away with a lot of jumper wires. I should have some completed pics in a few days. I just applied Deft lacquer sander sealer. I will paint it tomorrow, and add texture the day after. I have also added some flares and roundovers. I am very happy with the looks at this point, and will get pics for you very soon.


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## fbov

Very nice XO implementation. I also did a bottom access hatch.

A word about interior surface treatment. The fluffy white stuff, commonly called fill, isn't intended as a wall treatment. You want your walls to look like this:
http://www.zaphaudio.com/ZDT3.5-insides.jpg

The picture is Zaph's ZDT3.5 interior, with upper and lower ported chambers. The walls are lined with carpet pad, looks like 1/2" thick. So are the insides of mine, doubled to 1" down the back. The only place I have fill in my towers is around the base of the port, similar to what you show, and in the cavity above the top driver, to minimize standing waves (170Hz fits in 40"). You want the interior volume open so the box can resonate. 

If you can't (or would prefer not to) remove what's there, try to pin it back. Cheese cloth and staples would work. You want that central column open between drivers and port, so lows resonate, but higher frequencies to be absorbed by the walls. 

Have fun,
Frank


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## steve1616

Thanks for the advise. I think I can pull the white stuff out pretty easily. What about the fiberglass in the back? I just layed carpet in my living room so I happen to have carpet padding to put in place.


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## fbov

Same story with the fiberglass, but with added issues if fibers can leak. It doesn't look like it'll interfere with the port, but I'd still put a layer of carpet padding over the fiberglass, to keep it from migrating, unless it's easy to pull. It's effective; I use it in my sub, but that's sealed. 

Have fun,
Frank


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## domwilson

Any update on these?


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