Clarity on Seas Thor Kit

[Scottmoose]

You're welcome.

Given that the Thor crossover needs some work anyway by many accounts, it would seem like an interesting project.

A thought -Small Thor would do nicely too. About a year back, I built (another) pair of Martin King's FE207E MLTL project. The boxes were standard. However, I then added large extensions to the sides. They were not acoustically part of the line, which remained normal because they were only external additions -the internal volume the driver saw did not change. I've attached a quick cross-section of the end result, drawn from above. The black part is the original box. The yellow parts are the separate additions built onto the sides (later filled with expanding foam to kill resonances). No, it's not ideal, but they were only a quick pair of test mules -I'd do a properly curved one for a final version. The effect on the sound was dramatic. Baffle step was pushed right down in frequency, to a point where room-gain was begining to take hold, so it was nicely flattened, in my own room anyway. No BSC circuit required within 30in of the rear wall. The whole subjective presentation altered too -the sound became much wider and deeper in particular. Very interesting effect, and worth looking into. Go for it!

Best regards
Scott

[imjatse]

I am working towards building the short thor, getting ready to order the kit parts next month. What would you think about modifiying the cabinet design as indicated in the attached (hopefully) image? I have been reading about baffle step and am beginning to get into the math, but I am new to it all so any guidance is appreciated. I notice in your design you keep it symmetrical front and back. Was this a visual design element of taste, or does it play a role in controlling any sound rebounding from behind? I was thinking that keeping the internal volume as designed, but adding the curved, extended front could look quite nice visually. Sadly I don't yet have the feeling for what impact it would make on the sound.

[Daveis]

I take it that the consensus is that the Thor is the best Seas kit going these days?

I havent committed to building a Thor or one of it's variants, but I take it that many of you believe it's the best kit under $1000?

What happens to the Thor if you remove the transmission line and make it sealed?

Am I misunderstanding that all the discussion in this thread is concerned with only the Thor's lack of bass performance under 100hz or so? Otherwise its a top notch kit?

[planet10]

Originally posted by imjatse
I was thinking that keeping the internal volume as designed, but adding the curved, extended front could look quite nice visually. Sadly I don't yet have the feeling for what impact it would make on the sound.

One of the axioms that the Thor family is based on is that it is essential to keep the baffle width the same as the original so that no modification is required to the XO.

dave

[planet10]

Originally posted by Daveis
I havent committed to building a Thor or one of it's variants, but I take it that many of you believe it's the best kit under $1000?

There are an aweful lot of "kits" for under $1000. Add taste into the equation and i doubt that that question could ever be answered...

dave

[Scottmoose]

Amen. Taste is an odd thing -we all like different approaches and value different things, so there's no definitive, sadly.

Given that the Thor's crossover isn't that great anyway according to quite a few who've built it, It'd probably be worth trying the curved, wider front baffle to see what happens. Crossover experts -what do you think? Not my field. What will happen in physical terms is that by having a wider front baffle, you will push the baffle-step to a lower frequency -exactly what that will be depends, of course, on the ultimate width of the baffle itself.

What would be the difference between the original Thor enclosure and a sealed box? Not a lot. The standard Thor enclosure is so heavily stuffed it's basically become a badly designed aperiodic enclosure. Dave and Martin pointed this out quite a long time ago. The frequency response curve for a sealed box of the same volume looks almost identical, though the respective impedences are a little different. A 'proper' aperiodic enclosure could be interesting though, and for almost no extra effort over a sealed type, you'd bet better FL and a flatter impedence curve. I tried simulating one a few pages ago. Not my best as I took a duff approach, so here's a proper one, done in the Ported Box sheet.

3/4in material assumed, & internal dimensions. 45in tall. 7.5in wide. 12.5in deep. Tweeter centre 10.25in down from the internal top. Stuff the enclosure 0.5lbs ft^3 of Dacron or similar from the internal top 25in down. Aperiodic vent centre 4in up from the internal bottom on the rear panel. Couple of options here. You can either use one or two Scan Speak aperiodic vents if you are so inclined, or take the cheaper and more easily tweakable, if not as pretty, option, and cut a hole / slot, and stuff it with reticulated foam or fibreglass, nominally 1.0lbs ft^3.

Best
Scott

[andy2]

Originally posted by Daveis
I take it that the consensus is that the Thor is the best Seas kit going these days?

I havent committed to building a Thor or one of it's variants, but I take it that many of you believe it's the best kit under $1000?

What happens to the Thor if you remove the transmission line and make it sealed?

Am I misunderstanding that all the discussion in this thread is concerned with only the Thor's lack of bass performance under 100hz or so? Otherwise its a top notch kit?

Hi Dave,

Before committing to Thor, why don't you consider these two sites:
http://www.humblehomemadehifi.com/
http://www.troelsgravesen.dk/Diy_Lou...r_Projects.htm

Unlike the Thor, which contacting the original designer ins probably not an option, these two designers above will stand behind their designs and answer all your questions.

[Scottmoose]

They're also better designs. I haven't felt the urge to come up with replacement cabinets for any of these, because they don't need it.

[Virtalahde]

This is a killer thread and I seem to come back to it many times. I just can't make up my mind with a project but out of them all, the Thor keeps me coming back. Mostly the Fat Thor.

People have been speaking about that Hobby HiFi mag article about a tweaked xover for the Thor. Is there a scan anywhere on the web?

What I see in it is that the L-C filter seems to be a centered too low. At least looking at the W18E datasheets say that the big resonance is some 500Hz higher than the filter is tuned to.. Dunno.

[jackinnj]

Originally posted by Scottmoose
A thought -Small Thor would do nicely too. About a year back, I built (another) pair of Martin King's FE207E MLTL project. The boxes were standard. However, I then added large extensions to the sides. They were not acoustically part of the line, which remained normal because they were only external additions -the internal volume the driver saw did not change. I've attached a quick cross-section of the end result, drawn from above. The black part is the original box. The yellow parts are the separate additions built onto the sides (later filled with expanding foam to kill resonances). No, it's not ideal, but they were only a quick pair of test mules -I'd do a properly curved one for a final version. The effect on the sound was dramatic. Baffle step was pushed right down in frequency, to a point where room-gain was begining to take hold, so it was nicely flattened, in my own room anyway. No BSC circuit required within 30in of the rear wall. The whole subjective presentation altered too -the sound became much wider and deeper in particular. Very interesting effect, and worth looking into. Go for it!

Best regards
Scott

Scott -- do you have a picture? I was thinking to do the same thing.

btw, after a long discussion with a wood-working friend over a fine bordeaux, we decided that we are now both too old to carry 4*8 sheets of MDF.