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fostex design search results [message #20425] Tue, 21 September 2004 12:17 Go to next message
jim denton is currently offline  jim denton
Messages: 162
Registered: May 2009
Master
Manuel--I'd really like to hear more on those mods---I think I have found a good "advanced" fostex cabinet designer---BD designs at www.diy-systems.com---on that site under speakers there are pics of the singular model---and he has several fostex driversto use and advice on the filters needed or not---I am thinking I can bulid singular boxes for the 206's I have and then save up for some of those 200's they mention---but sure want to know how to install that phase plug ---doesn't those guys at Horne Shoppe "dope" the drivers?? Driver experiments!!!! I need to hit a lottery!!!! Jim

Re: fostex design search results [message #20426 is a reply to message #20425] Tue, 21 September 2004 12:40 Go to previous messageGo to next message
Manualblock is currently offline  Manualblock
Messages: 4973
Registered: May 2009
Illuminati (13th Degree)
Actually Jim they run pretty cheap. The completely doped/phase-plugged/whizzer cone trimmed/ rewired version sells for under 300$ a pair. He just glues the phase plug onto the former. For 20$ he will e-mail complete set of plans and for another 60or 80$ you get all the other stuff like spikes and the top diffuser plate etc. 60$ for marine grade plywood and you are set, and they require no eq. I liked them better than the Lowther systems I have heard because they are the first true full-range in my experience.
I mean if you need a filter, then whats the point? Just build a good two-way.
I would recommend them to anyone who doesn't have the room for Pi Theater 4's in their home.

Re: fostex design search results [message #20427 is a reply to message #20426] Tue, 21 September 2004 18:54 Go to previous messageGo to next message
Martin is currently offline  Martin
Messages: 220
Registered: May 2009
Master
"I mean if you need a filter, then whats the point?"

Why would you make such a strong statement? If a filter improves the overall performance of the system, why not use it? Would you rather listen to an unbalanced overly bright shouting full range speaker system and be happy knowing it is still "pure" due to the lack of any filter while it continues to hurts your ears?

Not me, I'll take the filter. A filtered full range is still much better then a two way in my opinion, and also better then an unfiltered full range in most cases. I have successfully designed and built both multi-way and single driver systems and really prefer the filtered full range Lowthers.

Martin

Re: fostex design search results [message #20428 is a reply to message #20427] Tue, 21 September 2004 19:40 Go to previous messageGo to next message
Manualblock is currently offline  Manualblock
Messages: 4973
Registered: May 2009
Illuminati (13th Degree)
Your right; upon further reflection that post did come off as somewhat arrogant. You have a better understanding of this aspect of driver use and I defer to your judgement. Understand from where my position comes; that in fact I have always understood the purpose of a full range driver to be an attempt to avoid the deleterious effects of passive components on the speed and ability to resolve complex passages in the signal. As well as to represent a point source radiator. If it sounds better; it is better. Thanks for pointing that out; J.R.

Re: fostex design search results, (long, tedious, boring and insignificant) [message #20429 is a reply to message #20428] Tue, 21 September 2004 22:03 Go to previous messageGo to next message
TC is currently offline  TC
Messages: 41
Registered: May 2009
Baron
>>Understand from where my position comes; that in fact I have always understood the purpose of a full range driver to be an attempt to avoid the deleterious effects of passive components on the speed and ability to resolve complex passages in the signal.

==cookie for manualblock!

Studying systems, *anthropologically* one arrives at this logical approach above. Crossovers, passive elements made the Ar3a the flattest measuring speaker since Hirsch Houck Labs rocked to the Tijuana Brass in 1964. I listened to the 3a alot with Cat Stevens, early Eagles and flat was good. Not very dynamic but flat nonetheless.

If your system sounds imbalanced? Got news, it IS. Adding passives at the last step in the chain is like giving up, tossing in the towel because the rest of the system has failed to do it's job properly.

Why not tune the rest of the system actively? Keep that bloody speed and tonality only obtainable by directly connecting one voice coil to one output circuit.

By using amps and sources with characteristics "cheeuned"(tuned)for optimum (overall)performance, you mitigate response anaomalie where it won't be passed on down the line. If you are using low "refined" power, even a small xtra coil results in sonic wavy gravy and compresion because now you have 2 inductors in a row (voice coil + comp coil)which is always avoided in any circuit, except seemingly, speakers.

Why do amp builders obsess over coupling caps types brands flavors? Have a nice transformer coupled amp with no caps n resistors in the signal path? Gonna spoil everything the amp builder did to bring you gobs of dynamics and tonal complexity by using a gob of parts at the end of the amp loop (spkr cirkut)?

It's really all about *expectations*.

How much dynamics do you expect? How much dynamics will your wife allow in her living room. Do you mind some power compression at moderate volumes? How do you know what your hearing is right? Instruments? Do you know the pain of a violin?

TC



Re: fostex design search results [message #20430 is a reply to message #20428] Wed, 22 September 2004 06:02 Go to previous messageGo to next message
Martin is currently offline  Martin
Messages: 220
Registered: May 2009
Master
Hi J.R.

"Understand from where my position comes; that in fact I have always understood the purpose of a full range driver to be an attempt to avoid the deleterious effects of passive components on the speed and ability to resolve complex passages in the signal. As well as to represent a point source radiator."

I agree. The only thing I would add is the increased efficiency that seems to be a property of most full range drivers. Low Qts (0.2 - 0.3) and high efficiency (94 - 98 dB) come with the large magnet. If you can design the enclosure to compensate and balance the SPL response this is no doubt the best solution. If your enclosure is unable to do this then a filter can help. The enclosure is not necessarily a bad design just a different set of compromises (typically smaller size and less complex). I personally believe that the benefits of a filter are much larger then any claimed potential degradation introduced and can improve the design (including correcting phase shift associated with baffle step losses). I don't hear any loss of speed or detail with the filters I have used in my designs. If you apply too much filtering then I would agree that the advantages of full range drivers start to disappear quickly. Everything is a balancing act and a set of compromises.

Martin

Methinks you miss the point [message #20437 is a reply to message #20429] Thu, 23 September 2004 06:27 Go to previous messageGo to next message
Oberon is currently offline  Oberon
Messages: 20
Registered: May 2009
Chancellor
The speaker in its cabinet is a tuned circuit, and a passive one at that. It may be overdamped or underdamped and the whole amp/speaker circuit is a part of it. Bloody speed and tonality takes more than just blindly hoping that a single voice coil and a single output circuit are married into sonic bliss.

Re: Methinks you miss the point [message #20438 is a reply to message #20437] Thu, 23 September 2004 06:40 Go to previous messageGo to next message
Manualblock is currently offline  Manualblock
Messages: 4973
Registered: May 2009
Illuminati (13th Degree)
If you know all of the drivers parameters don't you get a pretty good idea of the electrical behaviour of the driver under most conditions. Consequently the amplifiers bahaviour could be tailored to a great degree to the speaker, ie. damping and output impedance etc. If you are using a single driver and it exhibits a defined behaviour in the box; you create a model of the driver/box that synergizes with the amp, that should be possible right. Made much more difficult as you ratchet up the complexity with the addition of more components. Am very interested in your's and others opinions on this. Thanks J.R.

Right on [message #20439 is a reply to message #20438] Thu, 23 September 2004 08:03 Go to previous messageGo to next message
Oberon is currently offline  Oberon
Messages: 20
Registered: May 2009
Chancellor
That's the point; Rather, it's several good points. Mainly, the speaker/box/amp are a complex circuit already. The voice coil should not be considered some kind of "pure" load by any stretch of the imagination. It is the least pure part of the circuit.

Re: Right on [message #20440 is a reply to message #20439] Thu, 23 September 2004 08:26 Go to previous messageGo to previous message
TC is currently offline  TC
Messages: 41
Registered: May 2009
Baron
>> The voice coil should not be considered some kind of "pure" load by any stretch of the imagination.

== In fact a voice coil physically connected to a cone is an load, changing with freq. A load that will introduce distortions into the final circuit of and amp. Never said it was pure. Quite the opposite. I simply maintain that ideally, you want this load to remain as pure as possible, especially when using amps that are sensitive to loads which are usually lower powered.

Why Biamp, triamp and quad amp? And why does dynamics suffer except when an amp is connected to only one voice coil no matter the strength of the amp? It's a load alright, just depends on what you expect that single load to do.

It's well established that individual amplifiers connected to a single coil modulate that coil better than trying to modulate several coils or elements. Look at all the spkrs like 4-ways that have individual amps on each driver, Meridian, Rushmore, Paradigm. Why all the fuss for connecting one amp to one coil?? Because it has lower distortion and greater dynamic contrast that's easily heard

>>It is the least pure part of the circuit.

==Right. So you have a simple circuit ie: the output circuit of an amplifier. You can trim and adjust with passive elements all you want. All I am saying is that it always results in non optimal dynamic behaviour, limiting the ability of the amp/spkr to swing dynamics.

TC

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