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#1 2006-04-29 19:40:53

Diogenio
Member
Registered: 2006-04-29

Taming the Shrew (FE103E)

Just got through installing new FE103Es in place of Radio Shack 1197s with Dammar and phase plug tweaks. Vented cab with ~ 8 L volume.

Observations:

1) IMHO, don't use 1197s for your serious speaker projects. The FE103 is miles better in terms of openness, clarity and distortion. The RS is a good cheap driver to play with, but can't compare to the "real thing." 103s are fairly cheap, too, just $30 /ea.

2) The 103E, like the 1197, has a pretty big bump in response between 2.5 and 10 kHz. Peaks at ~ +4 dB at 4.5 kHz.  It makes these drivers overall sound edgy, shrill and fatiguing.

To reduce the shrill, I played around with a number of parallel resonant notch filter circuits (the filter network is then placed in series with one of the speaker leads). The web-based notch filter calculators will get you close, but the 103 rises to 16 ohms at 5 kHz, so an error will be introduced using 8-ohm calculations.

My design was developed using PSPICE CAD software and then tweaked through listening tests.

I'm using a 6 uf capacitor parallelled with both a 0.18 mH inductor and a 5.2 ohm resistor. This will center the notch at 4.8 kHz and notch depth will be -2.5 dB. To increase the depth of the notch, try higher value resistors. A 6.8 ohm R will give you -3.1 dB, 8.2 ohms will produce -3.6 dB.  For my tastes, I like between 2.5 and 3.1 for the notch. Any deeper than that and I feel some of the "life" is sucked out of the speaker. Subtle, yes...but noticeable.

I'm using  2 x 3 uF polypropylene "Wonder Caps" I had laying around. Also tried paper in oil caps and did NOT like what I heard. The sound became really indistinct, like the stereo was on morphine or something. Not pretty at all. Same goes for Sprague 735 film/foils. Something was just not quite right. The Wonder Caps were best to my ears. 

Give this filter a try. You will need to experiment with different types of caps, so don't give up easily.  When it all gets dialled in, the results are truly amazing.  A big, open sound with no trace of harshness or fatigue.

Cheers,
Dennis
San Diego, CA

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#2 2006-04-30 04:53:19

Scottmoose
Member
Registered: 2005-08-01

Re: Taming the Shrew (FE103E)

Thanks for the suggestions Dennis. Now wait until you hear them in a BLH...


Dedicated to The Search

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#3 2006-05-10 14:33:57

tube9
Member
Registered: 2006-02-03

Re: Taming the Shrew (FE103E)

Diogenio wrote:

Just got through installing new FE103Es in place of Radio Shack 1197s with Dammar and phase plug tweaks. Vented cab with ~ 8 L volume.

Observations:

1) IMHO, don't use 1197s for your serious speaker projects. The FE103 is miles better in terms of openness, clarity and distortion. The RS is a good cheap driver to play with, but can't compare to the "real thing." 103s are fairly cheap, too, just $30 /ea.

2) The 103E, like the 1197, has a pretty big bump in response between 2.5 and 10 kHz. Peaks at ~ +4 dB at 4.5 kHz.  It makes these drivers overall sound edgy, shrill and fatiguing.

To reduce the shrill, I played around with a number of parallel resonant notch filter circuits (the filter network is then placed in series with one of the speaker leads). The web-based notch filter calculators will get you close, but the 103 rises to 16 ohms at 5 kHz, so an error will be introduced using 8-ohm calculations.

My design was developed using PSPICE CAD software and then tweaked through listening tests.

I'm using a 6 uf capacitor parallelled with both a 0.18 mH inductor and a 5.2 ohm resistor. This will center the notch at 4.8 kHz and notch depth will be -2.5 dB. To increase the depth of the notch, try higher value resistors. A 6.8 ohm R will give you -3.1 dB, 8.2 ohms will produce -3.6 dB.  For my tastes, I like between 2.5 and 3.1 for the notch. Any deeper than that and I feel some of the "life" is sucked out of the speaker. Subtle, yes...but noticeable.

I'm using  2 x 3 uF polypropylene "Wonder Caps" I had laying around. Also tried paper in oil caps and did NOT like what I heard. The sound became really indistinct, like the stereo was on morphine or something. Not pretty at all. Same goes for Sprague 735 film/foils. Something was just not quite right. The Wonder Caps were best to my ears. 

Give this filter a try. You will need to experiment with different types of caps, so don't give up easily.  When it all gets dialled in, the results are truly amazing.  A big, open sound with no trace of harshness or fatigue.

Cheers,
Dennis
San Diego, CA

Now what I have been told useing filters for the fullrange drivers is o.k. I just talked to a dealer and said anything blow the bump is o.k. Anything above the peak is tamed down by 6 db.Do you hear the H.F. tamed down a little or alot?I have not tried this yet.I am waiting for  A new driver to come out.jm

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#4 2006-05-10 17:51:33

GM
Member
Registered: 2005-07-31

Re: Taming the Shrew (FE103E)

Greets!

FWIW, the plot I have is only ~12.5 ohms.

Interesting about the PIO caps, they have always performed best for me and can't recall anyone noting poly caps as superior. Then again, I don't recall ever using notch filters, instead preferring to find acoustic solutions to acoustic problems.

GM


Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

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#5 2006-05-10 18:28:08

ron
Member
Registered: 2005-07-27

Re: Taming the Shrew (FE103E)

I don't recall ever using notch filters, instead preferring to find acoustic solutions to acoustic problems

Amen.
ron

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#6 2006-05-10 19:50:23

Zero One
Member
Registered: 2006-03-27

Re: Taming the Shrew (FE103E)

For the last few weeks I have been experimenting with my redback drivers in a double bass enclosure (4''inch drivers, 92db efficiency) they look very similar to the 103s.  They too have a pronounced midrange brightness and I wanted tame it, at first I thought I'd try a notch filter but in the end I just felt reducing midrange efficiency to gain balance seemed to be counterproductive, so I went down the acoustic path with a couple of twists.

All of these things made a substatial difference as expected:

Port tube length (the speakers have ports in both upper and lower cavities so this proved tricky)
Internal box damping
Cone damping with PVA and tissue paper
Speaker placement (still playing with this)

These things made big differences but I really thought they wouldn't

Cat 5 speaker cable and inner box cable (utterly amazing change this one)
Cat 5 interconnects also substantial
Cat 5 input cable to gainclone modules, subtle but better

Prior to this you'd have never convinced me that cable made much of a difference and I have tried some in the past, I stand corrected!

Now for the off-the wall ones

Adding an MDF ring to the front of the driver with rubber padding on the rear face, the ring has a chamfered inner edge and is about 18mm thick, it shields/covers the area of the roll surround which is cloth on these drivers, this smoothed treble a lot! I found or at least I think I found that a lot of sound comes out through the cloth from the rear of the driver and mixes with the front waves cause a type of mild HF distortion.

Chamfering the rear of the speaker mounting hole so the driver wasn't so shielded, this improved bass considerably.

Covering the front of the box with rubber non slip matting, reduced HF reflections I think, but it really make the speakers very focused and if your in the sweet spot it is an absolute hoot!

And finally and this is a bit odd I guess but it works well for these, I added little flat reflectors that sit in front of the drivers and are about 1/3 of the way in from the outside edge, they are adjustable and they reflect a little of the speakers output into the corners of the room, this nicely boosts the upper bass without effecting the mid/upper range.

I feel that high efficiency drivers of this size are probably very responsive to all sorts of small adjustments and these speakers are a good vehicle for testing changes to amp circuits, source components etc, in the end optimising the amp to go with the drivers may reap even higher levels of sound quality and I've now turned my attention to this.

Net result from all this, a pair of very efficient speakers that have an incredible midrange but nice tight bass and controlled treble, they are by far after all this tinkering the best sounding speakers I have ever owned, also by far the cheapest and simplest! There going to my daughter and I think she will be happy with them.

In the end I don't need any filters and thats a good thing, but I would be interested in trying just to satisfy curiosity, though I imagine they may have some negative effect on sound purity etc, but I'd be happy to be wrong if they can actually provide a method of fine tuning once all other avenues are exausted.

Hope it helps.

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#7 2006-05-12 12:41:46

Groucho
Member
Registered: 2005-08-20

Re: Taming the Shrew (FE103E)

I once replaced audyn MKP's with used pios in a speaker crossover and although the sound was much smoother (no more harshness as with the mkp's, much better colour/tone) they sounded terribly lifeless and slow --- After about ten hours this disappeared and they were superior on all fronts; this leads me to believe that some pio's might require break-in even if they were used before (be it several decades ago in my case).

Simon

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#8 2006-05-13 03:05:56

Graham Maynard
Member
From: Northern Ireland
Registered: 2006-04-27
Website

Re: Taming the Shrew (FE103E)

Hi Diogenio and Zero One,

In the past I cured excessive driver 'squawk' by folding and smoothing two strips of pool table covering (lambswool) and taping this horizontally across, but clear of the face of the driver in line with upper and lower edges of the centre dome, which is not obscured.

I tried a series network, but found the network and driver had different 'timing' responses, and that these errors can be incurably magnified by inadequate loudspeaker leads.

Cheers ....... Graham.

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#9 2006-05-13 06:25:44

Zero One
Member
Registered: 2006-03-27

Re: Taming the Shrew (FE103E)

Graham when you say "different timing responses" how does this sound in actual listening and why do you think the leads effect this, is it a capicitance issue. I ask as I want to try some experiments of my own, to satisfy curiosity but I'm looking for a few pointers as to likely problems.

LIke your idea with the pool table covering.

Thanks
Brad.

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#10 2006-05-13 13:12:37

GM
Member
Registered: 2005-07-31

Re: Taming the Shrew (FE103E)

Greets!

Caps that have been allowed to sit for long periods of time have to be reformed since they will tend to leak excessive voltage, so I guess you could call it a type of 'breaking in'.

FYI, if they aren't properly reformed then they probably won't perform their best, but more importantly, they've been known to explode hard enough to cause injury or a fire, so it's a good idea to properly reform them before either putting them in a circuit, firing up an old amp, or playing a speaker at high power too soon after hook-up, etc..

WRT why PIO caps are superior: http://members.aol.com/sbench102/caps.html

GM


Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

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#11 2006-05-13 16:07:19

Graham Maynard
Member
From: Northern Ireland
Registered: 2006-04-27
Website

Re: Taming the Shrew (FE103E)

Hi Zero One,

I am at a loss to put the sonic change into words.

Take baffle step compensation with the mid frequency turnover.

Yes the sound spectrum becomes more balanced and less fatiguing, but the clarity of reproduction also seems sectionalised because the timings of attack and sustain become different, such that there is a loss of the overall coherence for which we use a single driver in the first place.

If you apply any kind of filtering at the end of a loudspeaker cable then the cable magnifies the effect of those components.  I have run sine checks and measured as little as 0.1dB change in sine amplitude due to components, yet observed a noticeable change in reproduction due to the cable magnifying dynamic alteration.

It is cable R+L interacting with composite loudspeaker circuit R+L+C.

I wonder why you ask, have you noted anything ?

Thus I prefer carefully positioned 'absorbers'.  I too have used little reflectors but went on to use front supported dowel or tubing for their gradual reflection. 
Hardware shops sell lengths of chromed clothes rail;  now that is smart.
Maybe even the pool cloth could be mounted on dowel, again for the gradual effect.

Cheers ....... Graham.

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#12 2006-05-13 21:00:10

Zero One
Member
Registered: 2006-03-27

Re: Taming the Shrew (FE103E)

Hi Graham

Thanks for the response, I'm not much of a tech head when it comes to electronics and sound, I'm actually a digital imaging expert, but one thing I have learnt from that field is that a great print is a combination of often many, many small things that most folk think don't make any difference.  My approach to audio so far is if I can identify the why and how maybe I can do something about the problem/issue.

What I have found is that lots of things that supposedly don't effect the sound seem too, at first I just went with the flow of those who took a purely scientific measurable approach, but now I'm trying to look outside that box, though I don't think I can come at $2000.00 mains cables etc.

One thing that really started me thinking was gainclone chips, most people said they all sound the same or very similar and are only effected by caps, PS etc, yet I have built Lm1875s and 3886s and through my system can easily distinguish a different sonic signature, yet other than power output the specs are very similar.

Yes I did try a basic filtering mod a couple of weeks back and Yes something didn't seem quite right, maybe a muddying of the midrange or a lack of attack the information around the adjusted frequencies, I can't quite nail it, but I won't give up if I can find a solution. Meanwhile I guess I'm in the camp of making physical changes before all else, and the combined results of lots of little one are amazing.

Here is a new one, just did it yesterday.

My Redbacks Speakers (which I call Waveclones to go with my Gainclones) are double bass types, but they also have a rear firing port at the back of the box on the top outside corner.  This port is tuned to boost the upper bass, and yes it shouldn't work, especially in conjunction with the lower front port, but it does.  Anyhow I found that voices can be tuned by putting light open weave padding in the port for a more subdued effect or leaving it open for brighter more live effect, I found that by putting a reflector over the port and angling it so it bounced the sound into the corner of the room I could significantly bump up the upper bass without causing any other changes, which has the effect of making the midrange seem less pronounced. Every little bit helps when you only have 4 inch drivers! I could of course move the speakers to the corners but that ruins the sound stage so that was quickly dismissed.

Additionally I added a pair of helper tweeters yesterday, small car types.  Treble before hand was very good but it is now even better, and once again the extra upper highs make the mids seem less pronounced, lots of tinkering to do with this one but I think it is a keeper!

I'm now getting to the point where I need a matching sub/low bass system but that no doubt will be a whole new adventure.

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#13 2006-05-14 04:55:38

Graham Maynard
Member
From: Northern Ireland
Registered: 2006-04-27
Website

Re: Taming the Shrew (FE103E)

Hi Zero One,

Thank goodness you are coming at this from the empirical/practical side. 

Those who are the best educated tend to have lost their cerebral flexibility and so often demonstrate an unwillingnes to apply established theory in the manner necessary to investigate findings relating to electronic signal amplification and the wire transmission of dynamic waveforms.  They use their learned facts as weapons and cast obfuscating barrages of interference in the form of 'theoretically proven impossibilities' which then become impedements to everybodies enlightenment, especially their own !

I published some of this in Electronics World in 2004, but the magazine changed tack with a new editor before I finished.
I dropped out of diyAudio because I received too much un-moderated abuse whilst trying to explain.
I had a similar, though not abusive, experience last week at audioasylum/speaker asylum/looking for speaker cable.

All of the effects you ( and so many others ) note in amps and cables are due to waveform propagation delay, whether within an amplifier or an interconnecting cable. 

To make SS NFB amplifiers stable, designers fit a theoretically correct C.dom.  The C.dom renders the output terminal of the amplifier inductive to external stimulus, and this makes the amplifier generate an error voltage as it attempts to counter leading loudspeaker generated back-EMF currents.

Exactly the same situation arises with loudspeaker cable inductance as the loudspeaker terminals becomes L+R separated from the amplifier's output terminals.   100 milliohms and 10uH can give rise to dynamic induced waveform errors in the -40dB range, ie. audible.

All waveforms start off with the amplifier drive leading loudspeaker rest or its priorly established state, but due to loudspeaker C+L+R, and after 90 degrees at some narrow range of frequencies, the loudspeaker current flow can become leading. 
Initially the waveform undergoes propagation delay between the amplifier and speaker, but after that 90 degrees, or up to 360 degrees due to lumped crossover reactivity, some frequency bands of back-EMF lead the amplifier's output waveform and thus have a *negative* propagation delay.   Equally some propagation is increasingly lag delayed in time at some frequencies. 
Effectively the cable is like an electric spring which responds dynamically according to the energisation at one end and several other differently rated springs at the other !

The waveform error is due to loudspeaker system reactivity and its effect upon the loudspeaker cable or the amplifier, and the time periods taken for those leading or lagging 90 to 360 degree back EMFs to develop varies widely at different energised frequencies, so the composite waveform becomes distorted in time and reproduction coherence becomes irreversibly disturbed !!!

What needs to be bourne in mind here is that these interface induced errors are *not* directly related to the music signal that energises them.  Change the music, the amplifier, the cables or the loudspeaker, and the error either disappears or is changed;  not cured !!!

Bi-wiring does much to overcome the cable induced error because the the lagging and leading currents generated by one crossover circuit section plus driver cannot then directly affect the other - as long as - the amplifier itself does not have an inductive output characteristic. 

These are the reasons why changing the loudspeaker cables or bi-wiring can sometimes have appreciable effect, as especially with SS amplifiers, but then sometimes not, as with higher output impedance tube amplifiers where errors within the amplifier mask cable error.

So will lowering the amplifier's output impedance and lowering cable impedances, or mono-blocking resolve the situation ?
Only as long as this does not increase the loudspeaker or crossover sub-circuit Q appreciably at some frequency.
Which brings us to thoughtfully implemented full-rangers and planars !

None of this will show with sine testing because the dynamically generated back-EMFs settle within that first cycle before theory guys can make a sinusoidal measurement.

I have run simulations of this, but I need somewhere to post images, not just words.

Is it possible to post images on this site ?  Maybe in the 'Articles' section ?

Cheers for now ............. Graham.

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#14 2006-05-14 06:30:35

Martin
Member
Registered: 2005-08-31
Website

Re: Taming the Shrew (FE103E)

"Those who are the best educated tend to have lost their cerebral flexibility and so often demonstrate an unwillingnes to apply established theory in the manner necessary to investigate findings relating to electronic signal amplification and the wire transmission of dynamic waveforms.  They use their learned facts as weapons and cast obfuscating barrages of interference in the form of 'theoretically proven impossibilities' which then become impedements to everybodies enlightenment, especially their own !"

And those who are not educated (your word not mine) postulate "theories" of why something happens, the more complex the better, which they repeat enough times that it takes on a life of its own and propagates among the sheep.  Sorry Graham, I don't buy into your observations.  But that is just my opinion.

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#15 2006-05-14 07:08:53

Zero One
Member
Registered: 2006-03-27

Re: Taming the Shrew (FE103E)

Thanks Graham

Well I'm certainly not going to get into any argument of whos right or wrong and how and why, I clearly have no where near enough knowledge for that in this area, but my gut and ears and those several folk who have lisitened to my system as I have developed it over the past 2 months say that there are differences that don't just fit into simple explanations, somehow I feel there is much more we don't know....which is kind of exciting! I quite deliberately get anyone I can muster up to do A/B listens as I don't want the psycho-acoustics to come into it if I can avoid it, in other words I don't quite trust myself.

From the start of this current project my idea was to build a system where everything worked in sympathy with the other parts first optimise the speakers as much as possible, then the amp (which I started on today) then the pre-amp and finally the source.  Beyond that I intend to actually re burn all the music for the system after applying equalization in my sound file editor to suit the system. I guess you can say I have it bad, but its a really fun project.

Bottom line any ideas/ concepts are really worth investigating so long as they are within the system budget and so far I'm very happy with the results. In the end I hope that my journey can be as helpful to others as they have been to me!

Oh and today I played with the feedback resistors (down to 18 instead of 23) on one the clones and decreased the signal path lenght, shouldn't make a difference to the sound? Well according to my son who was blind tested on it, it did, smoother highs was his word! Which is what I thought, but I didn't tell him first. Why? Not sure, could be some very low level oscillation at high freq that blends with the original sound, doesn't matter really it just sounds better.

Anyhow we are probably getting off track her, perhaps we need a new thread on the synergy between amps and full range drivers etc?

many Thanks
Brad.

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#16 2006-05-14 09:25:09

ron
Member
Registered: 2005-07-27

Re: Taming the Shrew (FE103E)

None of this will show with sine testing because the dynamically generated back-EMFs settle within that first cycle before theory guys can make a sinusoidal measurement

Lets apply a bit of logic here. A sine wave end result is a combo of the actions upon that wave. The end result is just that. A different induction of energies or phase  on any given point will still be evident in the end.

Those who are the best educated tend to have lost their cerebral flexibility and so often demonstrate an unwillingnes to apply established theory in the manner necessary to investigate findings relating to electronic signal amplification and the wire transmission of dynamic waveforms.  They use their learned facts as weapons and cast obfuscating barrages of interference in the form of 'theoretically proven impossibilities' which then become impedements to everybodies enlightenment, especially their own

Sorry, but based on that statement there would never be any progress. In my job i have to constantly be innovative and develop new approaches, otherwize i would not be able to accomplish my job.

The waveform error is due to loudspeaker system reactivity and its effect upon the loudspeaker cable or the amplifier, and the time periods taken for those leading or lagging 90 to 360 degree back EMFs to develop varies widely at different energised frequencies, so the composite waveform becomes distorted in time and reproduction coherence becomes irreversibly disturbed !!!

Full range single driver systems have their problems. But if you look at it as if the changes in phase or the RC value is equal from one channel to the opposing channel then the signal response is equal in either time or amplitude as the wave arrives at a given point. To me and the studies i have done is the actual physical difference in distances to a given point has more of an impact due to the V of air causing a greater deviation of signal arrival time. Simply stated, its easier to balance two tranducers than many. This IMHO is one of the major attractions of single drivers. There are many converts to single FR drivers just because of the phase coheriency. Now this is where properly positioned CD FLHs or collimation has it all over direct radiators. There is less side wall reflection and a greater collimation of the wave producting less phase change (time domain) of a secondary signal arriving at a given point.

Is it possible to post images on this site ?  Maybe in the 'Articles' section ?

Please do, i am always interested in acoustical theory. However theory is just that, its never a proven fact till there are established facts to back it up.But even then there can be errors.I know , i made many in my youth.Sometimes i still do, but they are just not as obvious as they once were.
ron

Last edited by ron (2006-05-14 10:09:37)

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#17 2006-05-14 10:05:27

Zero One
Member
Registered: 2006-03-27

Re: Taming the Shrew (FE103E)

Hi Ron

What you've mentioned here strikes a chord for an experience from yesterday.

I added some helper tweeters (1' car types, so pretty small) to the redbacks, now they are as close as possible to the main drivers, (blu-tacked at present) just up to the edge.  When I played the system the sound was actually a bit better balanced, which is nice, but I noticed that the sweet spot was now not as tightly focused as it was, in other words there's more leeway, but you can't pick actual instrument positions quite as well. It is a subtle difference which in some ways is easier to live with but it goes to show perhaps just how well the single driver concept actually work in this regard.

Makes me wonder if coaxial drivers are possibly the best all round solution, I can't make the redbacks coaxial by putting the tweeters over the cone as they would shield the cone too much, but I'm sure there some good candidates out there.

Thanks Ron, your knowledge is well appreciated.

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#18 2006-05-14 10:14:32

ron
Member
Registered: 2005-07-27

Re: Taming the Shrew (FE103E)

From one of my articles ;

On the subject of plane alignment of transducers at crossovers.

1. This is an evaluation of first order crossovers at a 90 deg phase change.
2.  This is an evaluation of physical plane (vertical  plane placement) of the energy producing points of  two transducers.
3. This has impact on the order of wave points ( ie: points on a sine wave) and the time /distance of the arrival of the wave points to a given greater position.

If you look the given general concensus is that adding a first order crossover will give a 90  degree phase change. This means that the secondary transducer will see the signal at a later time than the first. The time that the second transducer will see the signal is based upon the V of the signal transfer circuit plus the added phase differential. I am not going into the " speed of electronic conductance" as this means very little in audio.
Given that at a 90 deg. phase difference that the signal will become effective the distance  is:

dis=(V/F)/4.
where: dis= distance
V= velocity of the medium
F=frequency in Hertz


This is fairly simple as at 1/4 wavelength it is a 90 degree phase change. So the time/distance of the phase change is dependant on the velocity of the medium ( air)  and the frequency.

Conclusion: Proper placement of the transducers in respect to the listener position should be taken into account for the difference for the phase point of the added delay of  first order crossovers. Physical alignments of the planes of energy production should be adjusted for the phase difference.
ron


Now this means that designers who physically aling the drivers energy producing points and then add a a XO(passive) are fooling themselves.

Makes me wonder if coaxial drivers are possibly the best all round solution, I can't make the redbacks coaxial by putting the tweeters over the cone as they would shield the cone too much

All depends on the energy producing plane difference between the two transducers and the frequency at the XO as well as the order of the XO.

Last edited by ron (2006-05-14 10:31:45)

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#19 2006-05-14 11:56:56

westend
Member
Registered: 2005-12-31

Re: Taming the Shrew (FE103E)

Graham-"Is it possible to post images on this site ?  Maybe in the 'Articles' section ?"
If you can't post the images in the Articles section there is a Technical section in the Gallery for plots, etc.. Looking forward to reading more about the electrical effects of/on signal amplification in this area. Forgive my lack of knowledge about the following: is what you describe as inductive time/phase aberations similar to hysteresis?
Ron-Can the crossover phase change from first order crossovers be dealt with acoustically (placement, waveguide, etc.) ?

Last edited by westend (2006-05-14 11:59:50)

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#20 2006-05-14 13:45:52

ron
Member
Registered: 2005-07-27

Re: Taming the Shrew (FE103E)

Ron-Can the crossover phase change from first order crossovers be dealt with acoustically (placement, waveguide, etc.)

example! if you were crossing over at 8 Khz to a tweet(first order), then the tweets plane of energy origin would be closer to the listening position by .42". Second order would be .84". As the XO frequency went lower the distances would increase. So if you are XOing (is that a word?) there has to be a match of phase point delay and distance for a given wavelength.
  Now in theory (we all know what that entails) a wizzer cone would be the perfect mechanical XO as the plane of energy is the same as the main cone. However as it de-couples there is a change in phase which varies from one driver to the next.
  At one time i thought there was no phase change using a wizzer, but GM corrected me and i tested further. I thought i was correct by adding mass to the wizzer, but all i did was bring the wizzer phase point a full 360 degree from the main cone.Yall gotta watch those O scopes and read them correctly.
  IMO one of the best tools for analysis is a dual trace O scope, one trace showing the input sine to the speaker the next to a sensitive mic. You can visually see the changes and differences as provided by the driver/room/alingment. Just have to be sure which phase you are looking at. Just remember, the horz trace line is a time /distance baseline.
ron

Last edited by ron (2006-05-14 13:54:54)

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#21 2006-05-14 18:34:58

Graham Maynard
Member
From: Northern Ireland
Registered: 2006-04-27
Website

Re: Taming the Shrew (FE103E)

Hi Zero One.

Equalisers affect phase so maybe you would be better to equalise playback audio rather than your audio archive.



Hi westend.

Thanks.  I see those files.  This looks ideal, but I don't yet know how to upload. 
Looks like there are many FAQs to read first;  then I'll get busy.

Magnetic hysteresis is generally an energy wasting non-linearity. 
Between an amplifier and loudspeaker drivers it is energy storage and the electrical effects that arise due to its delayed release that causes a coherency problem.  Much as with the way tuned or sealed resonant cabinets affect reproduction coherency.

Cheers ....... Graham.

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#22 2006-05-14 19:14:01

planet10
Member
From: Victoria BC NA Sol 3 Milky Way
Registered: 2005-07-28
Website

Re: Taming the Shrew (FE103E)

Graham,

The alternative for posting images is to place them out in wespace & link to them. I do't know how it is with your ISP but here, when you get an interent account, they give you some webspace to use.

If you want to try that, i can help walk you thru it (i also have lots of webspace too)

dave

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#23 2006-05-14 19:27:12

karlsonkab
Member
Registered: 2006-03-21

Re: Taming the Shrew (FE103E)

Hey Graham - any chance of you sometime posting the article on interaction of component, cable, speaker reactance with amplifier?
"blameless" amps can change quite a bit in sound character without hardly any change with pink-noise or swept-sine RTA. 
*******************
Hey Dave - might you offer Frugal-Horn flat pack sometime in the near futrure?

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#24 2006-05-15 04:10:56

Graham Maynard
Member
From: Northern Ireland
Registered: 2006-04-27
Website

Re: Taming the Shrew (FE103E)

Hi Dave,

I'm not au-fait with this cyberspace technology.

I particularly like the idea of adding text to this forum so that all concepts can be thoroughly discussed by other exponents.

Hi Freddy,

Electronics World (eventually) contributed to charity for copyright of my earlier writing.  I would need to rewrite again in little 'chapters', and will do.
It is not easy to build an amplifier that does not react to the load it is driving; "blameless" applies to resistor load examination ONLY.

Cheers ....... Graham.

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#25 2006-05-15 10:22:35

karlsonkab
Member
Registered: 2006-03-21

Re: Taming the Shrew (FE103E)

Hey Ron - coaxial is about all I like - at least listening up close where spatial discontinuity can happen where certain  high pitched insturments will jump upwards (assuming HF unit highest in tier).

I like those infamous Karlson boxes with coaxial (or slotted pipe waveguide) as give some sense of pitch and concussive power on drums, thunder, which don't hear/feel with things like La Scala or bass reflex plus their so-called reverb works on a "percentage" of recordings.  smaller couplers seem tricky but someone with patience might get one good with coax (?) I don't have the woodworking setup/space to get anywhere.

Here's some of Lapaire's very nice woodwork:

A 10" coupler loaded with 8" coax - there matters of trying to balance tuning, coupled-cavity peak and subjective height of image via reflector cant.  not a politcally correct design and can be finicky with drivers.

8 inch coax in 10" coupler - strong points punch and holographic sound much deeper than my open baffle. but the OB isn't adjusted yet and may not be representive of what they can do.  I've owned MG1 and Tympani 1D and IIRC were pretty good in some aspects.

Top deflector cant seems to affect image height. Cabinet is 22" tall.
k108coax7ct.jpg

15" coupler with 12" (Beta 12cx in this pic - Beta 12CX did OK but mine had qts ~0.6-0.7) and its normal waveguide as quasi-coax per model X15 1966 or so.  Cabinet 27.75" tall.
x1512tube1ta.jpg

Hi Graham - with tube amps, going back 70+ years and using triode/faux-triode and deleting the feedback loop seems to be one way towards nice sound although Z inteaction should be greater than amps with lower output Z.   my rough 40kg 2A3 amp has sat dormant for a decade - just don't feel (without any help) up to putting that system back together and have "over-collected" large stuff and built stuff which is large so now I'm pushed into the corner :^(

got no audio friends to come around for >10 years plu health funky so hobby not as much fun.

Best.

417A/5842Q IT 2a3 messy amp with UBT1 - ground buss probably is "backwards"
2a30uf.jpg

Last edited by karlsonkab (2006-05-15 11:13:39)

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