Half Chang to fit my need's ?

[lykkedk]

Hi all in here.

As i am a totally newbie, into loudspeaker's, i decided to make a new tread here. As seen before : which speaker's to choose ??

I have falling in love with the HalfChang design, but i am not sure if they are prober for my setup. (Hope they are through!)

I must confess, that i like loud music, with plenty Bass and soo, but i also like listning to clean music. The speaker's i have right now, i constantly stroggle with, to play loud enough with my equipment, but they simply are to hard to drive. My equipment, is two PassDiy F4's monoblocks (fully balanced), and a prober preamp. to drive them.

As mentioned before, i really like the HalfChang design. http://homepage.mac.com/tlinespeakers/FH/download/halfChang-map-051107.pdf
But i have a few quistion's on Driver's serieresistor's etc...

1. Is the preferred driver the FE206E + 4ohm series resistor ? http://www.lautsprechershop.de/pdf/fostex/fe206e.pdf

2. How big in watt must such a resistor be (5/10/20watt)?? and what type is preferred ? (metaloxie metalfilm ceramic wirewound) ?

I see that in drawing's of HalfChang, that 18mm. ply is preffered, is there any other thing's to consider, when buying wood for the project ?

Well, iam also wide open for combination, with an sub! (just a thought) ...

Jesper.

I attached a plan, for my living room, so that size's between wall's can be seen if any interest

 

[John L]

I have falling in love with the HalfChang design, but i am not sure if they are prober for my setup. (Hope they are through!)

I have to confess that I too like it's design. It has one asthetic advantage over the full blown Chang in that it is less intrusive in the room, and there are some serious advantages to that. Mostly dealing with the spouse.

Over at the PE forum they call it SAF(Spouse Approval Factor).

1. Is the preferred driver the FE206E + 4ohm series resistor ? http://www.lautsprechershop.de/pdf/fostex/fe206e.pdf

I also believe the FE207E will work just as well, if not better, since it is a shielded driver, allowing you to place it right next to your TV screen.

The Pioneer B20 full range should also work as well, I believe.

2. How big in watt must such a resistor be (5/10/20watt)?? and what type is preferred ? (metaloxie metalfilm ceramic wirewound) ?

I'm just guessing here, but I don't think it will matter, since the current passing through the line will not put it to enough stress to cause it to fail. I'm just guessing since I am no electrician. I'm sure someone else will correct me if I am wrong here. Naturally, the more it can handle the better.

I see that in drawing's of HalfChang, that 18mm. ply is preffered, is there any other thing's to consider, when buying wood for the project ?

Most 'so called' 3/4" plywood, here in the US, is also of that thickness, I believe. I did a conversion check and 18mm is 0.7091999999999999", which sounds right.

However, if you are going to use plywood, make certain that you buy the best quality you can. A good cabinet grade plywood, having a nice facing is preferrable. If you are going to paint it, then that is of less importance, but remember, a smooth finish also makes the best paint job.

Can you get a nice light coloured finish on plywood, such as maple, or highly figured ash? A nice maple veneered plywood, sealed in a 1-2 pound cut of shellac would be great. If you want it to be darker, you could use an "Orange" unwaxed shellac, or for a lighter shade, try a "Blond" or "Super Blond"

The nice thing about shellac is that when dissolved in denatured alcohol, the tone quality is imprinted into the wood just like a dye stain, giving it a uniform stain quality throuoghout the entire surface. This brings out the shimmer quality, and grain depth, of wood, such as maple. If the maple is highly figured, or what is also called 'fiddleback', the staining quality of the shellac makes the ripples stand out and shimmer.

And if the maple is also a 'bird's eye' maple, the eyes stand out as well. maple is one of the most beautiful woods, when stained with a dye stain, or sealed with a shellac. Most people don't appreciate maple because they are used to pigmentated stain, which used finely ground rock/pummace to inject color. Since the finely ground rock is much larger than the dye quality, it cannot get into the grain of hard, finely grained woods such as maple. Consequently few people work with maple on a DIY basis. But with a dye stain or shellac, the results can be amazing.

But enough with the woodworking. You are interested in the sound.

I would be interested in this project were I not already in the process of making my own project at this time.

 

[davidallancole]

To me, the FE206E with the 4 ohms of series resistance looks just like the FE207E spec wise. A few of the specs are different, but by a neglagable amount I would say.

The series resistance on the FE206E changes the total Q of the driver (Qt) allowing it to produce more bass in this bigger box. Without the resistance in series with the driver it would sound very week in the bass. You could save yourself the purchase and worry of the extra resistor buy buying the FE207E, if you want to go the Fostex route. You also get the added benefit of a shielded speaker which can be nice beside a t.v.

 

[bobtrancho]

Well, iam also wide open for combination, with an sub! (just a thought) ...

Jesper - I've sent you a longer reply to the email you sent me but in response to your idea about possibly needing a sub I'd recommend that you give the finished speakers a good listen first. Unless you are into heavy hip-hop or head banging rock, I think you'll be quite pleased with the Half Chang low end. I disconnected my sub and am very pleased.

At some point I'll have to ask Marting King if I can bring them over and have him run them through his measuring equipment, but I'm pretty sure that I'm getting a fairly respectable upper 30 hz on the low end. Your amplifier will have some effect on this, of course.

 

[John L]

I have a question here. How does the regular Chang and the half Chang compare to each other? Does the removal of the upper opening seriously affect the sound quality?

I'm curious here, because the half Chang is less symmetrical, but less obtrusive in the listening room.

 

[Scottmoose]

I designed it for the 207 -the 206 with series resistance is an option. Some would say that the latter is superior as the larger motor still provides some benefits. Then again, the 207 isn't exactly lacking on the old motor-power front -it's got a lower Q than most Lowthers. Then again, you can never have too much motor power. YMMV.

Adding series resistance raises Qe, reduces Re & weakens Bl (all of which has the effect of lifting Qt).

 

[lykkedk]

Jesper - I've sent you a longer reply to the email you sent me

Thanks Bob... hmm seem's that i did not recieve this mail... could you perhaps send it again ?

Thank's all for nice reply's... i am having newyearsparty real soon here, so i am not sure, that i can reply much more this evening....

Again thanks i really appreciate the great helping...

Jesper.

 

[John L]

I designed it for the 207 -the 206 with series resistance is an option. Some would say that the latter is superior as the larger motor still provides some benefits. Then again, the 207 isn't exactly lacking on the old motor-power front -it's got a lower Q than most Lowthers. Then again, you can never have too much motor power. YMMV.

Adding series resistance raises Qe, reduces Re & weakens Bl (all of which has the effect of lifting Qt).

Scottmoose, what is the difference between the regular Chang and the Half-Chang? Hasn't someone listened to each of them?

 

[Scottmoose]

AFAIK, nobody has built both for direct comparisons. The regular box will sound significantly larger, & have superior imaging, especially front-rear.

 

[John L]

AFAIK, nobody has built both for direct comparisons. The regular box will sound significantly larger, & have superior imaging, especially front-rear.

It would be interesting to see if there is a significant difference.

And here is another thought. What if the opening from the rear was to be placed on top, instead of on the bottom. Would that make a difference in the presense category, and would the single driver be placed high enough?

 

[Scottmoose]

Yes and no.

The driver position affects the overall response, plus of couse the driver in this case would be very close to the floor, so a complete new design, from scratch, would be needed. I've actually done one or two with a layout like that -they're probably buried in an email to Dave from some months back. I'll try to find them if you like. One had a big twist to the design.

 

[davidallancole]

Getting back to the original question, will the B20 produce more bass because of its higher Q in the same box? I would imagine they would hit a similar SPL level because the Fostex would be 3 db louder per watt, but the B20 has double the excursion capability.

What kind of music do you listen to? You might be better of going with a sealed fullrange or open baffle fullrange with a sub on the bottom if you want loud with lots of bass.

or these
http://www.fortunecity.com/rivendell/xentar/1179/projects/afterburner/Afterburner.html
http://melhuish.org/audio/DIYBX12.html

 

[Kensai]

Since the Changs are all BR cabinets at heart, I'm going to guess that the B20 will have a pretty good sized peak in the bass if put in the same cabinet. Having a higher Qts, the B20 wants a bigger box volume. Of course, in WinISD, even with DiYer measured specks, if put into an "optimal" BR box, the B20 will be pretty flat down into the 30s. Put a big vent or two on that size enclosure, and you're going get big and deep sound. Of course, we've got at least one Chang builder using B20 and maybe a couple who have built Half Changs for their B20s, so you might want to hunt around for their comments and impressions.

Scott,

I sketched out a twist on a DBVR for the Pio A11 (while I was struggling with my buddy's "Christmas Speaker Project"). They only want like 740 in^3, and as usual I was trying to shoehorn everything into standard, 4' cuts of lumber, not to mention wanted to keep the driver position as high as possible, so what I had was a narrow and not terribly deep 4' tall cabinet with the bottom vent just normal and the top vent up firing, looking sorta like the top of a BiB. This made the start of the vents far enough down a narrow volume that I was afraid it was going to start acting like an MLTL which I have no way of simulating, so I kinda gave up on it. I had also thought of just going full omni radiating with the mouths by jacking the whole thing up and just mirroring the top vent with a down firing bottom vent. One of the layouts had the internal volume looking like a parallelogram from the side, and made me want to call it a Twisted Chang.

Kensai

 

[Scottmoose]

No, the B20 will exhibit a touch less bass (gain) actually. See attached. Not half bad though. Supposed to be a lovely driver for the money. Wish they didn't cost such a daft amount in Europe or I'd have bought a pair before now to play with.

Yeah, I did similar things myself a while back (on paper / screen). Lots of interesting combinations available.

 

[planet10]

I designed it for the 207 -the 206 with series resistance is an option. Some would say that the latter is superior as the larger motor still provides some benefits. Then again, the 207 isn't exactly lacking on the old motor-power front -it's got a lower Q than most Lowthers.

We haven't played with 206/207 in Chang, but have done the 126/127 comparo in Brynn... initially we were pleased with 126 but with longer term listening we decided the series R was subtracting more than the 126 was giving, so preferred the FE127 overall. Now if you have a transconductance amp -- particularily a variable one, you could possibly remove the series R problems. (do keep in mind that we were using just the white coffin resisters... using Mills or similar should improve things. We did scoop up some high quality Fostex variable resistors for future experiments Looks like we could well have a variable transconductance amp soon too..

dave

 

[John L]

No, the B20 will exhibit a touch less bass (gain) actually. See attached. Not half bad though. Supposed to be a lovely driver for the money. Wish they didn't cost such a daft amount in Europe or I'd have bought a pair before now to play with.

Yeah, I did similar things myself a while back (on paper / screen). Lots of interesting combinations available.

You know, they are all so close to each other that the relative cheap price of the B20(here in the US anyway) makes it a Must Have proposition.

BTY, have you ever gotten anyone from the US to order them for you, and mail them direct? That way you would bypass all the extra expense,.......wouldn't you?

 

[Fast1one]

No, the B20 will exhibit a touch less bass (gain) actually. See attached. Not half bad though. Supposed to be a lovely driver for the money. Wish they didn't cost such a daft amount in Europe or I'd have bought a pair before now to play with.

Yeah, I did similar things myself a while back (on paper / screen). Lots of interesting combinations available.

This is why I went with the B20, its cheap in the U.S. and the enclosure allows me to upgrade at a later date to Fostex drivers should I want to

Since you are out of the U.S. you might as well go with the Fostex, I think you will be happy with the Half-Chang...

 

[Badwater]

Just completed a Half Chang build for my son and daughter-in-law:


Fostex Fe207E with FT17H helper tweeter
Baffle step with zorbel per Martin King virtual 207E project
18 mm Baltic Birch wit holely center brace
Kiity litter fill in base

Initial impression are good. Plenty of bass. Hooked them up in the HT rig for an initial run. Diana Krall live in Paris DVD sounded very good.

I Will bring them upstairs later today and compare them to my FE166ESR factory recommended BLH. I suspect that that the Chang's will be a little rough around the edges until they break somewhat.

 

[lykkedk]

Soo, what should i choose The fostex206e with resistor/coil or the 207 ???

After what i read, it's really dosen't matter, what i choose, am i right ?

Jesper.

 

[Scottmoose]

Correct. The 206 will probably have a touch more detail, though if you need to put it near a TV you'll have to stick a can or something around it as it's unshielded. The series resistance will probably drop sensitivity to just below the 207, so up to you really. They're both fine drivers.