jackinnj said:
Well, that gives me about 208 topics to look though... Could you be a little more specific?
Do you mean this one: http://www.diyaudio.com/forums/showthread.php?s=&threadid=14774&highlight=
That's where I got my info in the first place...
I find the Thor and Odin plots to be confusing. Based on other
D'Appolito work, I'm pretty sure they are on-axis room response,
which would include port contribution, but neither has much
low end oomph. The Odin says its port is tuned to 31 or 33 hz.
The plots don't look that different from each other. And the
Thor seems to roll off sooner than the Odin.
D'Appolito work, I'm pretty sure they are on-axis room response,
which would include port contribution, but neither has much
low end oomph. The Odin says its port is tuned to 31 or 33 hz.
The plots don't look that different from each other. And the
Thor seems to roll off sooner than the Odin.
jackinnj said:
I'm not familiar with this article, but my comments on the Thor are based on their published design on their website:
This is the plot I'm referring to:
An externally hosted image should be here but it was not working when we last tested it.
which is on the "measurements" link on the Seas website documenting the Thor design
The comments on the site don't match the measurements that they have shown:
"The -3dB point is 45Hz, with roll off of 12dB per octave below 45Hz. Usable in-room bass response extends well into the low 30Hz range."
If you look at the plot 30 Hz is approx 20 db down!!! I don't know about you but it bothers me when someone does a measured response plot and then tries to tell me an F3 that is totally contradictory to what the plot shows! Am I missing something here?
Thor
Hey Paul,
I read the article and Joe has the response pretty well documented with measurements through out the design process.
He seems to have done all his homework.
If you are confused by the Seas derived plots from the individual drivers, as one might be, the measurements shown were taken from the drivers mounted in a small sealed 12 liter test box, and they do roll off early (~100 Hz). See note above the plots. Seas measures all drivers in this manner, and seem to be a breath of fresh air from most manufacturer's well smoothed responses.
Just a little misleading if only a cursory look.
Tim
Hey Paul,
I read the article and Joe has the response pretty well documented with measurements through out the design process.
He seems to have done all his homework.
If you are confused by the Seas derived plots from the individual drivers, as one might be, the measurements shown were taken from the drivers mounted in a small sealed 12 liter test box, and they do roll off early (~100 Hz). See note above the plots. Seas measures all drivers in this manner, and seem to be a breath of fresh air from most manufacturer's well smoothed responses.
Just a little misleading if only a cursory look.
Tim
Measurements
Paul,
Looking further I found the plot to which you clearly referred and linked. No mistaking the early roll off, but I did see that it was normalized for one meter. Probably not sufficient distance to measure below 100 Hz accurately. Too much room interaction.
Joe put them up on stands measuring each woofer separetely, combined, the port itself, then the total combined. 44 Hz, although his own plot looks closer to 50.
Tim
Paul,
Looking further I found the plot to which you clearly referred and linked. No mistaking the early roll off, but I did see that it was normalized for one meter. Probably not sufficient distance to measure below 100 Hz accurately. Too much room interaction.
Joe put them up on stands measuring each woofer separetely, combined, the port itself, then the total combined. 44 Hz, although his own plot looks closer to 50.
Tim
this discrepancy in the measurements is one of the reasons i posted my message .
I assume to get the good low down response claimed , the box size would have to be increased to the original D'pollito measurements , not the smaller ones in the article ?
Can anyone confirm or comment ?
Thanks
Andrew
I assume to get the good low down response claimed , the box size would have to be increased to the original D'pollito measurements , not the smaller ones in the article ?
Can anyone confirm or comment ?
Thanks
Andrew
I think that the woofer-tweeter distance in a MTM and lobbing effects are given too much importance. Let's be clear: Keep the distance between woofer and tweeter to a minimum, that can't be bad. But crossing a tweeter too low is much worst IMO. In many successful MTM design (Ariel or Thor), crossover point is around 2500 Hz, a little higher than theory would allow.
In a real room, I think that lobbing effects are reduced because of the presence of a strong reverberant sound field. I hear many 2 ways with crossover point over 4000Hz and some sounded great. Some full-range design also use a supertweeter above 10KHz. The lobbing effects do not seem to be such a problem...
F
I think that this horse has been beaten enough. It does strike me as interesting that all those who've actually heard Thor love it, and all those who are nitpcking at its perceived potential shortcomings have not heard it. We shouldn't lose perspective on what counts, and that's how it sounds. Those without firsthand experience in that regard really aren't doing the original poster much good.
BillFitzmaurice said:
Oh, sure... The Irak war sounded good at first, too
. It was made to sound good, just as this speaker is made to sound good by putting the name tag of Mr D'Appolito on it 
. I don't want to say that this speaker does not sound good, but I want to say that a good objective look at the theoretical facts can help one learn about the product. Apperantly, some things that are wrong in theory, bot are not wrong in real life (or, with the Irak war, the opposite). So... It sounds great... but why? Is the theory wrong, the measurments, have the people bad ears... Don't get me wrong.. I thinkt this speaker will sound great, but that is even more reason to find out what the secret is
BillFitzmaurice said:
I've actually seen quite a few reviews where they were called bass-shy. I don't find this surprising at all since Joe faithfully followed Augspurger's tables (why didn't he just ask George for a copy of the software?) and then threw away a 3rd of the specified volune. I'd like to see someone run these drivers thru Martin's worksheets and see what comes up -- my gut is that one can do better than the Thor with the same drivers (which, by all accounts are excellent).
dave
BillFitzmaurice said:
If the response plots on the Seas site have been done properly, then it's quite reasonable to say that they are bass shy. F3@100 Hz makes this a fact that does not require one to actually hear the speaker. There is no nit picking here, just a simple and fairly obvious oberservation from the information available.
BillFitzmaurice said:
How a speaker sounds is very subjective, and everyone will have different views and preferences on this. When it comes to helping someone decide on a DIY speaker project, both subjective (how it sounds, which is always an individual opinion) and theory-based comments are helpful. A balance of the two is needed. Yes, how it sounds is what counts, but that in itself is only half of the input that is appropriate.
You post implies that the comments of those who haven't heard the Thor aren't helpful or valid. And let's give the original poster some credit for being able to consider all the input from everyone and make up his own mind.
Re: Measurements
Surely D'Apolito knew how to measure correctly! If you accept that Joe is the expert and knows his stuff, why then say that he didn't measure his own design correctly?! Isn't is more logical to suggest that he made a compromise to make the size more acceptable?
Remember that this is a TL and it has two drivers. It is actually quite small in terms of cross sectional area of the line relative to the combined SD of the drivers.
"normalised to one metre" ... to my understanding this means that the levels are adjusted to reflect what they would be at 1m. That it is required to "normalise" would suggest that measurement did not take place at 1m. Seas have the means to measure speakers properly! It was probably done in an anechoic chamber.
"too much room interaction"?
I see no evidence of room interaction in the response plot. The bass rolloff is extremely smooth. If there was significant room interaction I would expect to see fairly sharp peaks and dips.
There is only one response plot on the Seas website. If you have seen another plot, it must be for a different design I assume. Now if someone were to give a link to another plot, this might change things and substantiate claims of an F3 @ 44 Hz.
Having a TL myself I can certainly agree that the inroom response can go very low. Depending on the room it's not out of the question to have useable output down to 25 Hz.
Bratislav said:
Surely D'Apolito knew how to measure correctly! If you accept that Joe is the expert and knows his stuff, why then say that he didn't measure his own design correctly?! Isn't is more logical to suggest that he made a compromise to make the size more acceptable?
Remember that this is a TL and it has two drivers. It is actually quite small in terms of cross sectional area of the line relative to the combined SD of the drivers.
Tim Moorman said:
"normalised to one metre" ... to my understanding this means that the levels are adjusted to reflect what they would be at 1m. That it is required to "normalise" would suggest that measurement did not take place at 1m. Seas have the means to measure speakers properly! It was probably done in an anechoic chamber.
"too much room interaction"?
I see no evidence of room interaction in the response plot. The bass rolloff is extremely smooth. If there was significant room interaction I would expect to see fairly sharp peaks and dips.
There is only one response plot on the Seas website. If you have seen another plot, it must be for a different design I assume. Now if someone were to give a link to another plot, this might change things and substantiate claims of an F3 @ 44 Hz.
Having a TL myself I can certainly agree that the inroom response can go very low. Depending on the room it's not out of the question to have useable output down to 25 Hz.
What my comments are trying to point out is that while those who haven't heard the speaker are busy caterwallering about how it can't have good bass response those who have actually heard it all vouch for the fact that it does have good bass response. That being the case, who do you believe?
The SEAS charts are wrong, by the way, and you'd have to ask them why. Although they clearly state in their literature that F3 is 45Hz their SPL chart says something quite different.
The actual response is flat within 2dB from 60Hz to 20kHz, F3 44 Hz, F10 30 Hz anechoic. I don't know how SEAS got its chart but clearly they goofed big time. It bears no resemblance to Joe D'Appolito's chart, and since he's not only amongst the world's top 5 loudspeaker designers but also the #1 kahuna when it comes to measuring speakers I'd be inclined to believe him.
The SEAS charts are wrong, by the way, and you'd have to ask them why. Although they clearly state in their literature that F3 is 45Hz their SPL chart says something quite different.
The actual response is flat within 2dB from 60Hz to 20kHz, F3 44 Hz, F10 30 Hz anechoic. I don't know how SEAS got its chart but clearly they goofed big time. It bears no resemblance to Joe D'Appolito's chart, and since he's not only amongst the world's top 5 loudspeaker designers but also the #1 kahuna when it comes to measuring speakers I'd be inclined to believe him.
BillFitzmaurice said:
for the benefit of non-English speakers, or those American children who have suffered through our public education system:
(Courtesy of Merriam-Webster)
Main Entry: cat·er·waul
Pronunciation: 'ka-t&r-"wol
Function: intransitive verb
Etymology: Middle English caterwawen
1 : to make a harsh cry
2 : to quarrel noisily
- caterwaul noun
Re: Re: Measurements
The more detailed plots are found in Joes article for AudioXpress. All response plots in this article show an F3 of the mid 40's. Note that in this article he does suggest that he had a lot of room gain and that added to the flat response. To quote from page 16
"2. Regarding bass extension— Figure 13shows an LF −3 of 44Hz,
with an ultimate LF slope of about 12dB/octave (similar to a
closed, not vented box). As previously mentioned, I heard what I
estimated to be strong 25Hz output. Figure 13is down about 12dB
at 25Hz, so I would say room gain is helping here."
Which would tend to support what Bill and others that have actually listened to it mention in regards to low end response being even better than the stated figures which is expected in room I guess. Dunno where seas got their figures from
I would agree and defer to the huge amount of talent on this site - however remember this is a kit and I am starting to learn enough to realise that it will take me several decades of DIY speaker building to be able to do better than such a design. Unless it was just a matter of increasing cabinet size?
paulspencer said:
The more detailed plots are found in Joes article for AudioXpress. All response plots in this article show an F3 of the mid 40's. Note that in this article he does suggest that he had a lot of room gain and that added to the flat response. To quote from page 16
"2. Regarding bass extension— Figure 13shows an LF −3 of 44Hz,
with an ultimate LF slope of about 12dB/octave (similar to a
closed, not vented box). As previously mentioned, I heard what I
estimated to be strong 25Hz output. Figure 13is down about 12dB
at 25Hz, so I would say room gain is helping here."
Which would tend to support what Bill and others that have actually listened to it mention in regards to low end response being even better than the stated figures which is expected in room I guess. Dunno where seas got their figures from
I would agree and defer to the huge amount of talent on this site - however remember this is a kit and I am starting to learn enough to realise that it will take me several decades of DIY speaker building to be able to do better than such a design. Unless it was just a matter of increasing cabinet size?
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