FX1000 build

dave shepard

I will be starting the build shortly using the drivers from 2 pair of RTi38's I have and am asking if someone would kindly send me some layout specs (peferably outlined onto a piece of paper or card board) it get the exact size and dementions. I will be getting the MDF and would also like to know if 3/4 is the proper thickness for them as mentioned in earlier posts (seems thick to me). I will reemburse for any shipping of you like. Also pics will be added while in process.

Thanks guys

Dave

amulford

I would think 3/4 would be a little thick, too. You could probably get away w/ 1/2". I would email someone and check.

I'm very interested in your project, I have an idea of something quite similar.

gatemplin

Dave, are you making a new crossover?

dave shepard

Originally posted by gatemplin
Dave, are you making a new crossover?

I will be ordering FX1000 crossovers and di/bipole buttons from Polk, that is all they say they have available beside the driver's and tweeters which I will not need because of the RTi38's I will be utilizing. I don't know if I should use the grills from the 38's or some other speaker, I asked about them also and they didn't include them in my part request so I assume they don't have those available either.

dorokusai

I would think that the dimensions off the FXi50 would also work. It has enough room cabinet wise to handle the drivers, and it's a little bit shorter than the FX1000.

This way the re-used RTi38 grills should cover the speaker faces completely. The bi/di switch for the FXi series is on the binding post assembly. There may be more parts available for the previous RTi series.

Just a thought.

gatemplin

Are the drivers in the 1000's the same impedance as the 38s? Otherwise the stock crossover will not work well.

scottvamp

Cool project Dave, sounds like fun - using 4 38's right?

I would think that the dimensions off the FXi50 would also work. It has enough room cabinet wise to handle the drivers, and it's a little bit shorter than the FX1000.

Actually the 1000's are about double the size.:eek:

gatemplin

I looked up the 1000s and the woofers total 8 Ohms while each 38 woofer is 8 Ohm. Which means they will either be 4 or 16 Ohm and the crossover will not work well at all. You can still use the stock 38 crossover and put them in parallel for a 4 Ohm total or design a new crossover.

dave shepard

Originally posted by gatemplin
I looked up the 1000s and the woofers total 8 Ohms while each 38 woofer is 8 Ohm. Which means they will either be 4 or 16 Ohm and the crossover will not work well at all. You can still use the stock 38 crossover and put them in parallel for a 4 Ohm total or design a new crossover.

I will be looking into that tomarrow when I call Polk for the parts. I did look into the 38's cabnet and they are made from 3/4 MDF w/Oak Vaneer so building the cabnets will not be a problem but if I have to do something with the crossover does anyone have any suggestions or have modified them before?

Dave

dave shepard

Ok..... I made the call to Ken (one hell of a guy) and he had said that they haven't made an 8ohm driver in years that all the drivers are coinsidered 8ohm compatable and that they would probably work but might sound different and that he could not guarantee one way or the other because of all the different veriables in the way each driver is made and the way each will perform with the other componets.
So what I desided is this...... he went looking for parts and dug and dug and came up after looking through all the available parts and found that they did actually have all the nessary parts (including cabnets) to completly assemble a set of the ever popular FX1000's. I couldn't believe it!!!!, I had to catch my thoughts, after mauling it over I went for it and ordered the whole complete parts list. All I will have to do is assemble them. I will post the assembly when the parts arrive (probably early next week). I am still looking to build a set using the 38's driver assemblies and will post the project when it gets started and I am also coincidering putting the 38's drivers in the bought assemblies to report the differances before the build gets started to get a comparison test.

Dave

goingganzo

cool how much do parts for a 1000 cost vs a used one?

scottvamp

Originally posted by goingganzo
cool how much do parts for a 1000 cost vs a used one?

Ya - what was the cost???
Now that you mention it all my Polk speaker manuals say"8 ohm compatable". What up with that? Lower ohm drivers curved with a crossover.
Can I get better performance switching my reciever to "6" ohms?????? I now question........

dave shepard

I think just a little bit more then the avarage price for used ones found on E-bay.
The exact price I'm not sure (???$700 incl. shipping and Pa tax)cause Ken had to check on some parts as to weather or not they came with the cabnets or not, he called and left me a message saying that the parts needed to be bought seperately (I think bezels and mount brackets were the parts in question) in the end I didn't feel it was a big deal having to purchase them, Polk deserves it. They will be absolutely brand new. He did say (I think) they only had one more of the cabnets not sure if it was the Lf or Rt. I don't know what the diff. would or could be between them they have the same drivers for both sides of ea. cabnet but they are marked for thier respective sides.

Dave

gatemplin

Dave,
you are spending a lot of money and I dont want you to be disappointed. One of my hobbies is DIY speaker building and I can tell you that the crossover is not going to work well. The 1000 crossover is designed for an 8 Ohm impedance total so all the components are designed for that. The two RTi38 woofers can combine for 4 or 16 Ohms and that will not work well at all with a crossover designed for an 8 Ohm total. The new crossover will probably still protect the tweeters but the transistion will probably sound bad. I dont know how you can solve this problem but I strongly suggest that before you lay out the money and time, you get the advice of some DIY experts at home theater forum or DIYaudio.com.

Frank Z

http://clubpolk.polkaudio.com/forum/showthread.php?s=&threadid=20289

dave shepard

Originally posted by gatemplin
Dave,
you are spending a lot of money and I dont want you to be disappointed. One of my hobbies is DIY speaker building and I can tell you that the crossover is not going to work well.

I am spending the money for a pair FX1000's in kit form, everything including the....
drivers (4),
tweeters (4),
grills (4) (2L/2R),
cabnets (2) (L/R),
xo's (2),
di/bipole buttons (2),
mount brackets (2pr),
bezels (4)
I was going to try the 38's drivers in them to see the differance between the drivers if the sound is less then favorable then I would report it and explain the simptoms, but I will also have the proper drivers and tweeters here also to put back in to have an originaly configured set. Do you think tring this will harm the crossovers in the speakers or the Denon?, the harm to the Denon would be bad compared to the crossovers, not that I want anything bad to happen. If it wont work that's ok, I was and am just courious to see what it would be like to get the newer drivers to be in the FX1000 form of configuration. so long as nothing bad happens it's mostly all for fun. What about the 70's crossover? there are 2 of the same drivers as the 38 in there, right? would that work inplace of the 1000's crossover?

Dave

dave shepard

Originally posted by Frank Z
http://clubpolk.polkaudio.com/forum/showthread.php?s=&threadid=20289

Thanks Frank,
I have seen them but I know it will quickly get high the last 2hrs of the auction I've bid on almost everyone since I first asked about them (way back when) and I was wanting black. This way to I will find out more about the inner workings of them and also gives me something else to do besides working 7/ 12-15hr days. The extra build of the cabnets (woodworking/ building) is something that I enjoy when I get a free moment. Lately I've been working my regular 8am-5pm M-F and then doing my after hour business (till 8 or 9pm sometimes longer) 7 days.

Dave

gatemplin

I mistunderstood that you were buying the drivers too. That should be a fun project. The problem with trying the 38 drivers is that the crossover point will change. Possibly that point is too low and the tweeters may be damaged, I dont know but I wouldn't risk it. There is no risk to the denon or XO, just the tweeters

dorokusai

Have fun with the project, great idea, and remember pictures

dave shepard

I went to the bank yesterday to make a deposit and had them check for the last transaction and it was for the 1000's parts from Polk posted monday, so the parts are on the way....... YAHOO! finally baged a pair even though they were slightly more the E-bay's average price, I just don't care when they get here I will post pics and then the extra build will begin. Any thoughts on using the RTi70's crossover? What other crossover might be interesting to try?

Dave

gatemplin

No other crossover will work properly. When designing the 1000, Polk would take into account the number of drivers, the impedance of all 4 of the drivers at the crossover frequency, the space between the drivers, the angle between the two baffles, the size of the baffles, the frequency response in dipole and bipole, the fact that they will be placed along walls, the impedance or sensitivity matching, and even more factors. The crossover is very specific. It would be like trying a Dodge Caravan computer (ECM) in an Intrepid.

Take some pics when you get the parts. I think it would be fun to make a brand new pair of speakers.

dave shepard

I recieved the parts Friday and haven't had a chance to look at them till this morning because we went to the Mt. Carmel fair in Niles, Oh and didn't get back till midnight. When I got up this morning it was raining pretty hard so the outside work luckly didn't have to get done which left me the time to get these things together. I first looked at all the parts sent and seen that there were no screws to attach the bezels or the mount brackets. There were also only 2 brackets when there should have been 4 a look at the invoice showed that I was only charged for 2 so monday I will be ordering the brackets and the screws that I took from the 38's I have in the closet. I also found that the di/bipole switch is to be attached with a flat nut simular to that found on a lamps socket to tighten it from turning on the all-thread pipe. I looked for 2 hours at Lowes and even looked at cable splice connectors and they were all too big or had the wrong thread. My last resort was I went to a car stereo, HT guy and he gave me a box to look through and I found the 2 nuts I needed and gave him $1.00 for them (he turns out to be kinda strange but that is for another thread). I then went to my local Handy-Man in Hubbard, Oh for the other screws I was in need for (because Lowes had nothing I could use) and came home with black phillips screws to put the 38's together until I get thr replacements. This pic is of the parts that go into making 1 FX1000 (with exception of the 2 tweeters that are for the other FX1000).

dave shepard

This pic shows the install of the crossover and di/bipole switch and button. The lable for the switch had to be trimmed to allow the button to be put on because the hole on the cabnet is bigger then the hole on the lable. I just put slices from the lables hole to the edge of the cabnets hole edge and folded the excess inward to give it a clean all black look even though you don't and can't seen it with the grills in place I lust wanted it to look clean every where. I also found that the only driver effected by the switch is 1 tweeter the wires are wire tied in pairs and each pair has its own color the tweeter wires each have different sized plug ends so you can't get them mixed up. The mids have the same sized ends but the drivers have a paint mark on one side of the terminals and according to the 38's wireing the painted mark is where the colored wire goes so I did the same on the 1000's.

dave shepard

This pic shows the size differance between the 38's driver and the 1000's. The 38's are shurly thicker the the 1000's which when I attempted to place the 38's drivers in the 1000's cabnets the magnets would hit each other priventing me from putting them in to try and compare the differance or even if they would work. the 38's rubber surround id stiffer then in the 1000's drivers and the build differance is obvious, would have been interesting to give it a try but with the stock cabnets it is impossable, the cabnets would have to be at least an inch wider to allow for a flush fit (which I still will give it a go by building my own version of the cabnets when I get somemore time). The cabnets have no ports and no baffels (except the tweeter has a backing) inside they are just a box, the 38's have 2 port tubs and the tweeter hole has the same backing as the 1000's. I also put wire putty in the wire hole of the tweeter as the 38's have the same.

dave shepard

This pic shows one finished FX1000. it took aprox. 1 hour give ot take I did alot of looking and lolly gagging. In a previous pic you can see under the mids hole what appears to be another hole it is not it is where a port might be for some other speaker type I reall don't know but the port flare in the bezel sits inside of the shallow indent. I took a black Sharpie and colored it so I wouldn't be visable, I don't know if they are all that way but I colored mine in anyway. I hooked it up and everything worked as it should the first time. I tried the di/bipole and the sound differance could be heard without even tring to listen for the differance big change given the equal dirvers on both sides that is for sure.

dave shepard

forgot the pic

sorry

dave shepard

I then went to work on the second 1000 and repeated the same process and the same result was had. The build was fun and quite entertaining it gave me something differant to do and gave me some ideas for the next project soon to be shown as soon as I get somemore free time. Finnaly after being out-bidded and late to get to the starting gate I scored a pair and the sound is very rich and full. The 1000's were and are worth it. While they may be big to some, after you live with a PB2+ for a while their not that big looking afterall and like the SVS you can quickly forgive the size given the sound that is produced. I will leave these in the rear for a while and see how things go as you can see in the pic I don't have much user friendly wall space in the back or the one side of the room so we will have to see what we can do about that at a later date. Hope you enjoyed the build tour as much as I did doing it. Build 1 over.

Dave

dave shepard

Dam forgot again:D

VR3

FWIW -

The RTi38 magnet is actually the same size, the bucking magnet and the VC - etc are in that 'container' -- from the pic it dosnt look like the FX1000 has a bucking magnet or was not put on, and dosnt have the container that the RTi38 woofs do --

Anyway,

The build looks like fun, tons of fun actually - makes me want to order speaker parts of speakers instead of buying them! LOL, anyway....congrats on the new surrounds and I will be interested in seeing ur custom build as well!

PC Ez!

- Trey

dave shepard

Originally posted by Vr3MxStyler2k3
FWIW -

The RTi38 magnet is actually the same size, the bucking magnet and the VC - etc are in that 'container' -- from the pic it dosnt look like the FX1000 has a bucking magnet or was not put on, and dosnt have the container that the RTi38 woofs do --


- Trey

The 1000's have the bucking magnet they just are half the size as the 38's.

Dave

scottvamp

Dave - that is awesome!!! Glad it worked out and it seemed like a fun project to boot. Sweet.......... Cozy looking crib you got thier!