Questions on building Thor

BrianGT

diyAudio Moderator Emeritus
2002-01-21 2:42 pm
near Atlanta, GA
www.chipamp.com
I started building a pair of Thor TL speakers this past weekend.

Will the design be negatively effected if I increase the thickness of all of the walls? I would like to make the walls 3/4" mdf covered in 3/4" red oak, resulting in 1.5" thick external walls. The internal transmission line will remain 3/4" mdf, as called for The internal volume will be the exactly the same, except for that the drivers will be mounted 1/2" farther out, due to the thicker front baffle. The drivers will remain flush to the baffle. The original design calls for 1" mdf, and I will have a combined 1.5" front baffle, and the speaker cabinet 10" wide instead of 9" wide. How will effect the sonics? Will the phase be effected by a wider cabinet?

Has anyone else built Thor? I am wondering if it is worth the effort to biamp this speaker also.

--
Brian
 
You will probably want to rout some relief into the rear of the baffle so the woofer cut-outs will not be so "cavity like."

The extra width of the enclosure will slightly change the baffle step frequency.

Assuming that you use an active crossover that can mimic the curves of the passive, bi-amping will remove the complex load introduced by the passive network. This is usually a good thing but may not provide audible benefits. On the other hand, you will be introducing another active component which may contain op-amps. As you know, some people hate op-amps mostly because much negative feedback is used. I have no problem with them but some would say that if I can't hear the negative effects of an op-amp, my system lacks resolution. These are the same people, by the way, that don't seem to realize that the audio signal has already gone through many op-amps in the recording and mix-down chain.

Considering the effort in getting the active crossover to match the passive one (an "off the shelf" design will probably not do this), you could very well be better off sticking with the passive.
 
BrianGT said:
Will the design be negatively effected if I increase the thickness of all of the walls?.... the speaker cabinet 10" wide instead of 9" wide. How will effect the sonics? Will the phase be effected by a wider cabinet?

Wall resonances will change, probably for the better. You have to make sure the driver holes are reamed out at the back so that you don't get a tin-can resonance or restrict the radiation from the back of the driver.

A 1" wider baffle will effect the exact diffraction characteristics. A roundover to make the baffle appear to start at 9" might be an idea, as would using PaulV's Baffle Diffraction Simulator and optimizing driver placement for the new baffle (i'd do this even if only building with the stock width.

Has anyone else built Thor? I am wondering if it is worth the effort to biamp this speaker also.

Haven't built one but it is very likely bi-amping would be better. You do have to take care to emulate any filtering built into the passive XO.

dave
 

BrianGT

diyAudio Moderator Emeritus
2002-01-21 2:42 pm
near Atlanta, GA
www.chipamp.com
Assuming I do this:
-Stick to a single amp for each speaker, and keep the same crossover
-The current design is 9" wide and routed with a 3/4 radius. I will increase the angle so that the actual flat part of the front baffle is similar in dimension to the original layout.
-I will route the inside of the baffle opening, as to make it less of cavity.

Following these suggestions, are there any more considerations to the design?

Should I route the bottom of the internal piece of 3/4" mdf that seperates the two parts of the transmission line? The plans do not route this.

If I was to bi-amp this speaker, using the standard crossover:
http://www.madisound.com/thor_std x-over.pdf

Would this be advantageous?

Thanks for your suggestions!

--
Brian
 
Originally posted by BrianGT
Assuming I do this:
-Stick to a single amp for each speaker, and keep the same crossover
-The current design is 9" wide and routed with a 3/4 radius. I will increase the angle so that the actual flat part of the front baffle is similar in dimension to the original layout.
-I will route the inside of the baffle opening, as to make it less of cavity.

Following these suggestions, are there any more considerations to the design?

Should I route the bottom of the internal piece of 3/4" mdf that seperates the two parts of the transmission line? The plans do not route this.[/QUOTE]

That should do it. The bottom of the internal bffle is fine square.


If I was to bi-amp this speaker, using the standard crossover:
http://www.madisound.com/thor_std x-over.pdf

Passive bi-amping -- not nearly as effective as an active XO -- seems a waste of an extra identical amp unless you already have it kicking around. Better would be to use one amp for M+T and the other for the other M, but then you would have to retool the LP sections of the passive XO anyway so you might as well tool an active one.

dave
 

BrianGT

diyAudio Moderator Emeritus
2002-01-21 2:42 pm
near Atlanta, GA
www.chipamp.com
Thanks for the advice,

One more question: When routing the inside of the speaker cavity, how much do you think that I should slope the inside of the front baffle. I have the 3/4" radius routing bit that the original design calls for for the edges. Might this suffice?

As for bi-amping, I will try it, using two 2 channel amplifiers, and compare and then decide if it is worth it.

An entirely different question concerning amp placement, if I was to bi-amp (or use monoblocks), would it be wise to put the amp directly next to the speaker, using short speaker cables, and long cables from the pre-amp, or would it be better to run long speaker cables with short interconnects between the pre-amp and the amplifier. For now, this is assuming a non-balanced cable running from the pre-amp to the amp, but later on, it will be balanced, using my bosoz and aleph 2.

Thanks,

--
Brian
 
BrianGT said:
One more question: When routing the inside of the speaker cavity, how much do you think that I should slope the inside of the front baffle. I have the 3/4" radius routing bit that the original design calls for for the edges. Might this suffice?

A picture would be best, but can't find one quickly. Between the bolts you want t route out as much of the baffle as you can get away with consistent with creating no obstruction to the open spaces on the back of the drivers.

An entirely different question concerning amp placement, if I was to bi-amp (or use monoblocks), would it be wise to put the amp directly next to the speaker, using short speaker cables, and long cables from the pre-amp, or would it be better to run long speaker cables with short interconnects between the pre-amp and the amplifier. For now, this is assuming a non-balanced cable running from the pre-amp to the amp, but later on, it will be balanced, using my bosoz and aleph 2.

You will get people responding from both camps. Do use one amp for each speaker -- if the stereo amp has only one supply you will effectively increase the available supply for the Ms.

dave
 
Here is the picture. It's routed more than usually but there is another plate coming from the other side.

As to cables it also depends on the cost. Speaker cables are usually more expensive, so I like t keep them short and interconnects long.;)
 

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Asen

Member
2001-01-14 1:19 am
Sofia
I have no experience with THOR, but I am an ODIN owner. The SEAS Excels are excellent drivers, but they need compex XOs. The idea of spliting the XO for the two woofers ain't good at all. In this case you should use bigger coils that will affect the sound more than you can imagine. The drivers are very detailed and very sensitive to what is in front of them. I mean not only the XO parts but cables and the whole system you have.
Bi-wiring is good. And it costs nothing - just two speaker terminals (as a start - I don't count the amps here).
You've made a good choice. I also think of rearanging my own ODINS into TL encosure (in the near future - 2-3 years).

About the damping stuff. Be ready to open the speakers a thousand times to put more or les of it. It's a time consuming procedure. And no measurements could help - only your ears. Don't put more then it's enough or you will kill the excelent drivers.

One more thing - these speakers are a difficult load for many amps. You will need a realy good one.

Regards

Asen
 

BrianGT

diyAudio Moderator Emeritus
2002-01-21 2:42 pm
near Atlanta, GA
www.chipamp.com
Peter,

Thanks for the picture, it makes it much clearer.


As for splitting the crossover, that is more work then I intend on doing. I get much more enjoyment out of implementing a design, rather then engineering a design. The existing crossover seems pretty solid, so I am not going to mess with it.

As for bi-wiring the speakers, I will try that along with running a single pair of wires, and trying bi-amping the speakers.

As for connections, does anyone have any opinion on the new speak-on cables? (there was a new thread on them yesterday). They handle 40A continuous and seem quite convienient for bi-wiring, as they contain 4 contacts.

[IMGDEAD]http://www.neutrik.com/images/ock/sublevel/view/1_204_1108942548.jpg[/IMGDEAD]
Neutrik SPX connectors

[IMGDEAD]http://www.neutrik.com/images/ock/sublevel/view/2_204_672560351.jpg[/IMGDEAD]
Neutrik STX connector

Do you think that the Aleph 2 will handle these speakers alright?

--
Brian
 
Response to BrianGT's question about the new Neutrik Speakon SPX and STX connnectors...

I just got some of the SPX connnectors and like them a lot. I am using them in a bi-amp situation so the 4 pole configuration saves a lot of time. One "click" at the speaker end of the cable instead of fiddling around with 4 separate lugs. There is some play in the lock position but a connector rated for 40 amps should be providing plenty of contact area and presure.

I was waiting for the more sexy STX line but I now notice that Neutrik has pushed back their introduction until 2003!

I settled on Speakons after much deliberation on mainly the disadvantages of bananas and spades.

It's expensive to get good binding posts that offer good surface area to really clamp down on spades and locking bananas cost a fortune. Non-locking bananas are affordable but locking bananas are not.

I am curious if anyone has comments or observations here.
I'm surprised more people don't comment about them.