I suppose if the opening in this mini TL behaves as a point source (at all frequencies where you expect dipole behavior) and the rear wave behaves as if coming from a monopole then all should be well. I can't comment on whether TL theory can apply to a system where the driver area is so much larger than the pipe -- seems like compression driver models would be more applicable -- but what do I know. If you're full of ****, I'm full of ****^2 
Please accept my comments as something that caught my eye that perhaps should be considered, nothing else.
- Eric
Please accept my comments as something that caught my eye that perhaps should be considered, nothing else.- Eric
sreten...and Martin
we have a measured 6dB drop , I have incorrectly (again) stated what I had thought.
Yes the 12dB drop is required, we do have a fairly accurate impedance plot for the pair of drivers (tested by planet10 himself), and are attempting avoid any resonance.
Not sure what is sucking the life out of the Jordans though. Maybe the tube amp (22kΩinput impedance), or maybe the quality of the caps. Once listening full-range to the Jordans the Jordan magic reappears. All we really need is a crossover that can work and is "transparent" enough for the top end. I have plenty of amps about, from A Stasis receiver to a McCormack DNA 0.5, to T-amps, etc. If the KT88 based amp isn't suitable, then we can switch as well. I suspect that is also part of the problem though.
stew
we have a measured 6dB drop , I have incorrectly (again) stated what I had thought.
Yes the 12dB drop is required, we do have a fairly accurate impedance plot for the pair of drivers (tested by planet10 himself), and are attempting avoid any resonance.
Not sure what is sucking the life out of the Jordans though. Maybe the tube amp (22kΩinput impedance), or maybe the quality of the caps. Once listening full-range to the Jordans the Jordan magic reappears. All we really need is a crossover that can work and is "transparent" enough for the top end. I have plenty of amps about, from A Stasis receiver to a McCormack DNA 0.5, to T-amps, etc. If the KT88 based amp isn't suitable, then we can switch as well. I suspect that is also part of the problem though.
stew
Re: sreten...and Martin
Hi,
An input capacitor can be combined with a line level RC filter
to give a low Q 12dB / octave filter and this may work well
at the right frequency to suppress the baffle hump a little.
The requirement is the pre-amplifier can drive ~ 10 times
lower impedances than the amplifers input impedance.
I have seen 12dB/octave line level filters made using inductors
similar to the coils in transistor radio's, whilst this will work and
work well, I expect most "audiofools" would reject the concept.
For the latter we have the vagaries of "subjective testing".
With no objective information you have no real idea what is
going on or in fact what is being described. The statement :
"losing their ability to emotionally involve the listener"
does not give you much to go on and nothing to analyse.
It is difficult to add anything useful to smoke and mirrors analysis.
/sreten.
Nanook said:
Hi,
An input capacitor can be combined with a line level RC filter
to give a low Q 12dB / octave filter and this may work well
at the right frequency to suppress the baffle hump a little.
The requirement is the pre-amplifier can drive ~ 10 times
lower impedances than the amplifers input impedance.
I have seen 12dB/octave line level filters made using inductors
similar to the coils in transistor radio's, whilst this will work and
work well, I expect most "audiofools" would reject the concept.
For the latter we have the vagaries of "subjective testing".
With no objective information you have no real idea what is
going on or in fact what is being described. The statement :
"losing their ability to emotionally involve the listener"
does not give you much to go on and nothing to analyse.
It is difficult to add anything useful to smoke and mirrors analysis.
/sreten.
Berm please contact me
Sorry for the intrusion on this discussion, but this appears to be the last place Berm posted anything. And I can't seem to send a direct message to him.
Berm can you contact me about the following:
"It occurred to me while watching this thread that this - Mamboni’s DIY omni - may be just the ticket for a great mono speaker. I’ve been looking for something that would provide great sound for 78’s and mono LP’s, and provide it over a wide area. No beaming speaker wanted for this. The one difference I think is that here an omni tweeter, or tweeter array, would be desirable in this case."
thanks, Ohighway
Sorry for the intrusion on this discussion, but this appears to be the last place Berm posted anything. And I can't seem to send a direct message to him.
Berm can you contact me about the following:
"It occurred to me while watching this thread that this - Mamboni’s DIY omni - may be just the ticket for a great mono speaker. I’ve been looking for something that would provide great sound for 78’s and mono LP’s, and provide it over a wide area. No beaming speaker wanted for this. The one difference I think is that here an omni tweeter, or tweeter array, would be desirable in this case."
thanks, Ohighway
Asif the goalposts in this hobby are not forever moveing, this gentleman seems to have a few ideas I have not heard before...
http://www.sausalitoaudio.com/pdf/SAU_MixArticle_WPaper_R1.pdf
http://www.sausalitoaudio.com/pdf/SAU_MixArticle_WPaper_R1.pdf
Just to second Martin - I use an Alpha 15 in a 16" by 16" H frame, which he designed recently. I was playing rock loud last night, and thought to watch the driver for excessive excursion. Visually, you can't see the driver moving, only holding my finger very close could I feel the driver moving. Not exactly scientific, but still nowhere near the 3.5mm peak to peak linear excursion. I have it crossed 4th order at 125Hz, and use almost no EQ.
Martin, thanks for another great design and write up!
Martin, thanks for another great design and write up!
Re: Re: sreten...and Martin
Regarding "subjective" vs "objective", I'll take subjective impressions over objective testing any day. Not that objective testing does not have a place, but for me (personally) it is the impression I am left with that provides me with the experience of listening to a piece of music via whatever equipment I might have listened it through. Just because something measures well, doesn't mean it sounds good. And of course there are those pieces of audio legacy, tube amplifiers that generally measure poorly but sound good.
As always sreten, your comments are completely valid and to the point, and I do appreciate your point of view, regardless of whether I agree completely with it or not.
stew
Not looking for any means top overcome any hump... but rather a good place to cross the Jordans over to help reduce the demands on them in the bass regions.sreten said:
Well, I really don't care what others do or don't--if inductors can work, I'd be willing to give it a try, regardless of comments from those who follow fashion, rather than function ( as opposed to those that might follow the "Craftsman" or "Arts and Crafts" movement in design where both form and function have been regarded as being equally desirable)
Analysis can be over done, and in this case the comment made is a subjective impression. So there really isn't much to say other than the top end became very recessed, and everything else sounded like the sounds were coming from a speaker with a wool blanket thrown over it. It sounded "muffled"
True, but this wasn't an analysis, and no smoke and mirrors intended.
Regarding "subjective" vs "objective", I'll take subjective impressions over objective testing any day. Not that objective testing does not have a place, but for me (personally) it is the impression I am left with that provides me with the experience of listening to a piece of music via whatever equipment I might have listened it through. Just because something measures well, doesn't mean it sounds good. And of course there are those pieces of audio legacy, tube amplifiers that generally measure poorly but sound good.
As always sreten, your comments are completely valid and to the point, and I do appreciate your point of view, regardless of whether I agree completely with it or not.
stew
Re: Re: Re: sreten...and Martin
Hi,
Well one would argue if first order highpassing an amplifier logically
the way to do it is to "upgrade" the input coupling capacitor with
a higher grade lower value component.
Its effect should either be "undetectable" or an "improvement".
But objectively and subjectively to do its job it is anything but
"undetectable", there will be an audible, and is a measurable
difference due to the high pass filter.
It seems you added the capacitor to the input rather than
replaced the input coupling capacitor and surmised it sounds
better without the capacitor.
The leading question is why ? not just this is what happened.
What about the actual input capacitor ? the pre-amplifiers output
coupling capacitor ? (if any, in or out of a feedback loop), the pre-
amplifers input coupling capacitors ? etc etc back to the source.
Why does your input capacitor cause an effect none of these do ?
How can replacing the input capacitor with a better component be worse ?
If it is, then then it is the highpass function itself that is wrong .....
/sreten.
Nanook said:
Hi,
Well one would argue if first order highpassing an amplifier logically
the way to do it is to "upgrade" the input coupling capacitor with
a higher grade lower value component.
Its effect should either be "undetectable" or an "improvement".
But objectively and subjectively to do its job it is anything but
"undetectable", there will be an audible, and is a measurable
difference due to the high pass filter.
It seems you added the capacitor to the input rather than
replaced the input coupling capacitor and surmised it sounds
better without the capacitor.
The leading question is why ? not just this is what happened.
What about the actual input capacitor ? the pre-amplifiers output
coupling capacitor ? (if any, in or out of a feedback loop), the pre-
amplifers input coupling capacitors ? etc etc back to the source.
Why does your input capacitor cause an effect none of these do ?
How can replacing the input capacitor with a better component be worse ?
If it is, then then it is the highpass function itself that is wrong .....
/sreten.
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