6.5, 8", Chang, Sachikos? Xmas project

[Bob, W7ETA]

For no good reason, I've got the bug to build some speakers. Its probably related to rebuilding PP EL84 integrated rigs. I'm listening to a Scott 222B that I've just changed the output caps to Russian PIO while I am rebuilding a Scott 299B--it worked fine. I just enjoy totally rebuilding these simple tubed rigs.

For the present, I plan on getting a Big Box place to cut up some Birch plywood for that I can make a 14x12x14 box for Fostex 8 inch full range speakers.

With box-plot. I varied the speaker dimensions and didn't find any significant differences by making the box a little larger. It did seem as if there was a slight benefit to using the FE206E vrs the FE208ESigma I want to buy, at least in this small box. If the 208Sigmas do sound great, I'll use them in a larger box and get OK sounding drives for the small box.

To begin with, this will replace a pair of Paradigm Titans, 89db two ways with a simple xover that I've replaced the stock cap with Russian Teflons.

Now, I'm considering buying Birch 4X8 or 4X4s and building either a Chang or Sachikos for the Fostex drivers as a Christmas project. Santa might bring me a table saw. Since I've never done wood working, I'm not sure if I'll use a table saw for anything more than building these speakers, or, if I really need it to build speakers with mostly 90 degree angles. The cost of the table saw might be put towards a cabinet company just cutting up what I need to put the cabinets together?

The room I want to put these in is around 18X18 with a solid half height wall into a much large living room. On the back side of this room is another half height wall opening onto my kitchen. There are cabinets from the ceiling down above the hall wall with a resulting 16.5 inch opening into the kitchen.

My thought is to use corner horns. Since I'm a widower and live alone, I'm free to make function over ascetics play toys.

My objective is to make high sensitivity, easy to drive with tubes speakers without xovers or need for correction inductors. While imagining is nice, I don't need to be able to pin point the lead violinist on a symphony stage--I can do that with my vinal system in my living room. Most of my listening now is Muddy Waters type blues, and old time late 60s rock. I've had a Hsu sonatube type sub for years that I've used for movie playback, but its been a few years since I've bothered to rent a movie.

This new system will be used just for FUN listening where I won't be using vinal, or at most, or occasionally spin an album with an inexpensive used Technics.

I'm currently using PP El84s but have a HeathKit 5881 monoblock waiting to be rebuilt. I'm intrigued by trying 6B4 triodes in place of the 5881 types of tubes or simply running the pentode as a triode. Eventually I'll find a mate for the Heath monoblock.

In advance, thanks for your insight, experience and suggestions for drivers, cabinet and needed tools.
Bob

[Ty_Bower]

Originally Posted by Bob, W7ETA

Santa might bring me a table saw. Since I've never done wood working, I'm not sure if I'll use a table saw for anything more than building these speakers...

I had never used a table saw before I started building some Makizou clones. I found an inexpensive (and cheap!) used one on Craigslist. I found it difficult to use without a little practice. Get some cheap chipboard, and make lots of trial cuts before you start the actual project. Don't expect your first box to turn out to your satisfaction. I'm not trying to discourage you from going for the saw and doing it yourself - to the contrary, I highly encourage it! Just realize it is a skill which requires a little time to develop. Oh, and look for a table that's nice and big. The cheapo little two foot wide tables (like the one I found) are too small, and make everything harder than it needs to be.


http://s69.photobucket.com/albums/i4...u/P1120533.jpg
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[Bob, W7ETA]

I melted a lot of plastic insulation on wires while teaching myself to solder; lifted a few traces on printed circuit boards.

I use military surplus teflon coated wire now--much higher melting point and prefer point to point wiring.

Thanks for your suggestions.

Bob

[rjbond3rd]

Originally Posted by Bob, W7ETA

...The cost of the table saw might be put towards a cabinet company just cutting up what I need to put the cabinets together?

That's what I'd do. But if you do get a small table saw, have someone there to help you. Mine is one of those little $99 models which can tip over easily, and can kick. Nowadays, I get the lumber shop to do at least all the rips, then I just trim the lengths. Ah, the lazy life.

[planet10]

Neither FE206 or FE208 will do all that well in a BR box. Both work quite well in Sachiko.

dave

[Scottmoose]

Better that 'quite', although I say it as shouldn't.

[Bob, W7ETA]

Thank you for your considered responses.

Are there drivers better suited to the Chang style cabinet?

Are there better cabinets than Sachiko suited to the Fostex drivers? The frequency response curves I see for the Sachiko look like undesirable saw-tooths to my untrained brain.

I see a lot of information for Frugal-Horns. I shy away from those plans because all the angled cuts look daunting. Building the box looks doable.

Best from Tucson
Bob

[planet10]

Originally Posted by Bob, W7ETA

Are there drivers better suited to the Chang style cabinet?

Are there better cabinets than Sachiko suited to the Fostex drivers? The frequency response curves I see for the Sachiko look like undesirable saw-tooths to my untrained brain.

The Chang cabinets are best suited for Fostex FExx7 drivers (in the fostex lineup) and many other drivers suited for bass reflex use.

The upper frequency in the sims does not take into account the many low pass filters in Sachiko style horns and in practise those ripples do not exist.

When Scott gets some time, he has promised to generate a more detailed sim (a lot more work, and really unnecessary as far as designing them goes) to be able to (at least partially) illustrate this point. Scott is very busy at the moment thou (work, school, family and his other work) and this is not high in his queue.

dave

[Bob, W7ETA]

Thank you for your time.

I went back and looked at the drivers again, and there it was, right in the driver description, bass reflex and back loaded horn.

Bob

[yan6]

I have just built a curvy chang with a FE207. A friend at work had previously built sachiko's also with the FE207. They are both good cabinets, I find the imaging on the changs a little nicer. They are also a fairly simple build. I think room size and placement is a big question the sachikos are huge and need a large room to work well. I have my changs in a 12x12 room and they seem to work very well.