FE207E Half Chang Build
I will be doing a Half Chang build over the next several weeks. I will eventually be giving these speakers to my son.
I have purchased two FE207E drivers and have purchased the parts for the baffle step. For the baffle step I am using the guidance given by Martin King on his Quarter-Wave website for the FE207E virtual project. I chose parts for a high damping factor since the speakers will be SS driven. The baffle step I chose uses a 1.8 mH Super Q inductor in parallel with a 6 ohm mills resistor. I have also included the zorbel recommend by Martin. My plan is wire it up and let it rip.
For the enclosure I will be using 70 mm Baltic birch. I am having the lumberyard cut the birch since my motto is to measure 2-3 times and cut it either too short or too long. I have used this lumberyard in the past and they do wonderful work that is well worth the additional cost to have it done right.
I have a few of questions:
(1) How tight should the internal brace fit to the back of the FE207E? I will be doing duct seal on the frame and a couple of layers of felt on the back.
(2) Any suggestions on how to connect the negative terminal to the frame? Do you drill a hole and mechanically fasten the wire or do you solder it?
(3) Any thoughts on using a super-tweeter? I am thinking of adding a FT17 capped off. If I go this route where should I mount the tweeter? Under the FE207 off to the outside at about 28" above the floor?
I should be starting the project in a week or so. I will post pics as I go. Comments and suggestions are most welcome.
Thanks to Scott, Dave and others for developing and sharing these wonderful projects. It was tough deciding what to build!
Bill
I will be doing a Half Chang build over the next several weeks. I will eventually be giving these speakers to my son.
I have purchased two FE207E drivers and have purchased the parts for the baffle step. For the baffle step I am using the guidance given by Martin King on his Quarter-Wave website for the FE207E virtual project. I chose parts for a high damping factor since the speakers will be SS driven. The baffle step I chose uses a 1.8 mH Super Q inductor in parallel with a 6 ohm mills resistor. I have also included the zorbel recommend by Martin. My plan is wire it up and let it rip.
For the enclosure I will be using 70 mm Baltic birch. I am having the lumberyard cut the birch since my motto is to measure 2-3 times and cut it either too short or too long. I have used this lumberyard in the past and they do wonderful work that is well worth the additional cost to have it done right.
I have a few of questions:
(1) How tight should the internal brace fit to the back of the FE207E? I will be doing duct seal on the frame and a couple of layers of felt on the back.
(2) Any suggestions on how to connect the negative terminal to the frame? Do you drill a hole and mechanically fasten the wire or do you solder it?
(3) Any thoughts on using a super-tweeter? I am thinking of adding a FT17 capped off. If I go this route where should I mount the tweeter? Under the FE207 off to the outside at about 28" above the floor?
I should be starting the project in a week or so. I will post pics as I go. Comments and suggestions are most welcome.
Thanks to Scott, Dave and others for developing and sharing these wonderful projects. It was tough deciding what to build!
Bill
Re: FE207E Half Chang Build
Holy snapping... overkill probably -- how many plys in 2 3/4" BB?
(typo? 🙂)
very tight the felt should let the brace reach the actual metal of the magnet (perhaps best to put the felt on the brace
The terminal strip is mounted to the basket with a rivet -- you can solder to that. If you want to absolutely ensure electrical connection to the basket, scrape some of the paint on the opposite side of the strip and bridge some solde.
Chris & i have talked possibilities... for our 1st FE207eN (in Demetri) we are just going to mount it above centrally (as dicated by the elliptical sBaffle)
dave
Badwater said:
Holy snapping... overkill probably -- how many plys in 2 3/4" BB?
(typo? 🙂)
very tight the felt should let the brace reach the actual metal of the magnet (perhaps best to put the felt on the brace
The terminal strip is mounted to the basket with a rivet -- you can solder to that. If you want to absolutely ensure electrical connection to the basket, scrape some of the paint on the opposite side of the strip and bridge some solde.
Chris & i have talked possibilities... for our 1st FE207eN (in Demetri) we are just going to mount it above centrally (as dicated by the elliptical sBaffle)
dave
Thanks for the help.
I have decided to add the FT17. With respect to the bb it's a typo, I meant 18 mm.
Bill
I have decided to add the FT17. With respect to the bb it's a typo, I meant 18 mm.
Bill
Do we have a Half Chang design that would fit a Pio A11?
Pio A11 4.5" fullrange
I don't remember where I got them exactly, but here are some recent DiYer measured specs for them
Qts .578
Qms 1.96
Qes .82
Vas 3.43 l
Fs 109.14
Re 6.95
BL 4.51
Sd 63.1 cm^2
I prototyped a BR that WinISD told me was "optimal" and its kinda physically small and sounds it, even though its actual frequency extension is plenty low for my purposes. My prototype BiB for it, which has some issues, and really only beats the BR's extension by a few Hz, sounds alot bigger and pleasant. I was wondering if a half chang for it might get me alot of the "big" with some of the control and detail that the small BR has.
Kensai
Pio A11 4.5" fullrange
I don't remember where I got them exactly, but here are some recent DiYer measured specs for them
Qts .578
Qms 1.96
Qes .82
Vas 3.43 l
Fs 109.14
Re 6.95
BL 4.51
Sd 63.1 cm^2
I prototyped a BR that WinISD told me was "optimal" and its kinda physically small and sounds it, even though its actual frequency extension is plenty low for my purposes. My prototype BiB for it, which has some issues, and really only beats the BR's extension by a few Hz, sounds alot bigger and pleasant. I was wondering if a half chang for it might get me alot of the "big" with some of the control and detail that the small BR has.
Kensai
Another question: The brace is to be offset to prevent standing waves from forming. With batting applied to top, bottom and one side, which way should the offset be? Toward the side with batting?
Thanks,
Bill
Thanks,
Bill
Badwater said:
We aren't talking standing waves inside the box (althou an offset holey brace should help against that to0), but in the box panels.
I typically offset the brace so that an edge rests on the centre-line if we have a centred driver placement, centered on the back of the driver, if it is offset.
dave
Thanks. My current plan is to place two layers of felt the back of the driver and cut the brace to fit. To provide a tight fit I will add felt to the brace. The driver will be torqued to that necessary to seal and seat the driver. As recommended I will set the edge of the brace on the driver centerline.
I will pick up the cut lumber on Friday and start the build. Photos will be forthcoming.
Bill
I will pick up the cut lumber on Friday and start the build. Photos will be forthcoming.
Bill
This is message for Scott. I will be building the Half Chang's soon and planned to implement the BSC recommended by Martin King his MLTL 207E virtual project. The circuit is here:
FE207E Baffle Step with 6 ohm resistance
Is baffle step necessary for this design? The speakers will be SS driven.
Thanks for all the help and a great design.
Bill
FE207E Baffle Step with 6 ohm resistance
Is baffle step necessary for this design? The speakers will be SS driven.
Thanks for all the help and a great design.
Bill
FE2073 Half Chang Drawing?
Hi Badwater, sorry to trouble you but could you direct me to a drawing / plan / design for the FE207E? Thanks in advance.
Hi Badwater, sorry to trouble you but could you direct me to a drawing / plan / design for the FE207E? Thanks in advance.
Badwater said:
Should do fine. Martin implemented a variation on Jim's pair with 206s to good effect.
Gracias, sir.
You are a gentleman and a scholar. I searched for hours in order to avoid asking. I might be going blind... Thank you, kind sir.
You are a gentleman and a scholar. I searched for hours in order to avoid asking. I might be going blind... Thank you, kind sir.
Quick question: I'm close to finishing the HC's w/ FE206e for my daughter & son-in-law. I noticed that there is a slight warp in the ply 🙁 which resulted in the vent being almost 1/16" too wide. Is it time to panic & mod the vent w/ 1/16" panel to fill it, add a piece to lengthen it, or just try it & hope for the best. I don't know just how sensitive the tuning is to the vent X-section, but I know it will shift the tuning freq.
Thanks & Merry Christmas,
Jim
Thanks & Merry Christmas,
Jim
It will, but you will more than likely here little to no audible difference(fraction of a Hz change in tuning),...Jim Shearer said:
If it was half an inch I would be slightly worried, but don't lose sleep over it 🙂
It will change things, but the difference will be inaudible in practice, so I wouldn't get worried. The room they'll end up in will screw things up a whole lot more than that 1/16in ever will. That's what rooms do. 😉
Thanks guys! I just want to be sure about all the details before I glue the front baffles on and "seal the deal." Bob's HC's sounded so good, and I would hate to get a poorer sound due to letting tolerances slip too far.
Merry Christmas,
Jim
Merry Christmas,
Jim
BTW Jim, I finally rearranged the living room and got the Half Changs situated properly for optimal sound stage and equidistant from the listener. They're even better sounding now.
An externally hosted image should be here but it was not working when we last tested it.
Like what you did with the space... my cats will unfortunatly take 20 minutes before soiling it in one way or another.... somedays I think they are vomit with hair on.
We have two cats and, luckily, we were able to "train" them from when they were kittens not to go on the furniture (at least when we are around 😉 - The leather chairs show scars from their cavorting about when we are not there to yell at them.). Not visible in the photo are the clear plastic protectors on the corners of the sofa - they are probably no longer needed but were vital when the cats were kittens.
We still need to do a lot of vacuuming to keep the cat hair under control but, by and large, the cats seem to be honoring a sort of understanding about who goes where... or maybe it's us...
We still need to do a lot of vacuuming to keep the cat hair under control but, by and large, the cats seem to be honoring a sort of understanding about who goes where... or maybe it's us...
