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 Post subject: Re: Status of Douglas Fitzpatrick‟s Gramophone
PostPosted: Fri Nov 10, 2017 9:57 pm 
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Victor IV
Joined: Sat Jul 09, 2016 7:12 pm
Posts: 1098
emgcr wrote:
...
This slightly tongue-in-cheek experiment might amuse and perhaps seems to suggest that adverse effects of a constant diameter tube are less than one might expect ...


You're right! It sounds excellent--a real 3D effect.

OF


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 Post subject: Re: Status of Douglas Fitzpatrick‟s Gramophone
PostPosted: Sat Nov 11, 2017 8:25 am 
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Victor II
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Posts: 489
Location: Hampshire, England.
chunnybh wrote:
Is it on display and accessible to the public?.......how does it compare....?


Hello Chunny. I am afraid it is not on display in any public way but the owner, although very private, is a keen enthusiast who, I am sure, would be happy to see a kindred spirit by appointment. Let me know next time you are over and I shall try to arrange things.

You ask how this horn compares with the EMG Oversize ? The comparison mentioned earlier between a re-entrant and a directional horn is really the closest I can come to explain the difference. The Fitzpatrick trapezoidal horn is larger than the circular Oversize which does not make any difference to the volume, of course, as available energy is identical in both cases. The audio experience, however, is quite different in that the DF horn allows the available soundwaves to be dispersed over a wider area and the smallish room it occupies (perhaps 18' x 15'---guess) is indeed filled with good quality sound. More listeners are thus enabled to have an identical experience. With the Oversize horn, things are much more directional as you will know well from your own instruments. In my opinion, the concentration of sound in the latter case offers the listener a more magical experience. The detail and quality of the more focused sound is unsurpassed, not forgetting the "holographic" effect where the artist or instrument appears to be in the room with the listener. Also in my opinion, and in simple terms, the non-circular design of the DF horn does not seem to be helpful---corners surely militate against a smooth progression of the exponentially expanding spherical soundwaves ? Lowest bass resonances in both cases may be around 80Hz but they are heard to far greater effect in the case of the Oversize.

By way of further comparison, it is also interesting to note that, when playing the Decca frequency gliding tone records, the Oversize has no vices at all throughout the entire range. By contrast, the smaller Nimbus horn (which I am lucky enough to have here) demonstrates uncomfortable resonances at several frequencies due, I think, to a different exponential curve.

The intention is to carry out more detailed experiments and analyse the sound in a similar contemporary way and then also to do the same thing with modern "state of the art" electronic equipment to see exactly what is happening at various frequency ranges emanating from the DF horn.

The ongoing study is eternally fascinating............


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 Post subject: Re: Status of Douglas Fitzpatrick‟s Gramophone
PostPosted: Mon Nov 13, 2017 5:54 am 
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Victor III
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F. Depero, "Grammofono", 1923.
Joined: Thu Feb 24, 2011 4:19 am
Posts: 551
Location: Italy
estott wrote:
Not quite the same situation (at all) but I'm a saxophone player & sometimes the instruments are subject to "Motorboating" - an obnoxious throbbing vibration on low notes. This can be fixed by careful adjustment of the mouthpiece and neck angle, but a common quick fix is to drop the mouthpiece cap into the bell of the horn to rest in the bottom crook. (Many is the time I've thought "Where is that cap - Oh Yes..") There is the slight possibility that a bit of oil in that position might dampen an unwanted resonance.

I wish I could also play saxophone! 8-) I've never read before about this "motorboating" issue and its peculiar "cure"; I wonder why this motorboating takes place at all, and why it comes that a small object left in the bottom of the instrument happens to dampen it (without, I suppose, altering the tone or pitch).

However, as you have anticipated, aside frome the horn-like shape and (sometimes) brass material, there is very little parallelism among a musical instrument, which is a tone generator that produces standing waves, and a gramophone horn, which is an impedance adapter ran by traveling waves.


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 Post subject: Re: Status of Douglas Fitzpatrick‟s Gramophone
PostPosted: Mon Nov 13, 2017 8:29 am 
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Victor III
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Location: near Utopia, UK
Marco Gilardetti wrote:
a gramophone horn, which is an impedance adapter ran by traveling waves.

Exactly Marco. Theoretically the Fitzpatrick horn with its enormous speaking length and horn mouth should be able to produce frequencies lower than the largest EMGs and Experts can - however, it's said that EMG experimented with horn designs larger than the Xb Oversize but were unable to obtain any benefit.

Percy Wilson reported that the Fitzpatrick instrument was able to "track" (quote) a 30 Hz test cut accurately, but whether and how it actually delivered that frequency is unknown! As far as I can remember it gave a wonderful account of 32 ft. organ tone *, but subjective listening can be misleading. The large EMGs and Experts can do the same, yet it's a physical impossibility for them to reproduce such low frequencies - they are 'reassembled' from their upper harmonics, partly by air vibrations, and partly by the human ear/brain.

As Graham has said, we hope to visit again at some point and carry out more objective tests and careful listening.

* As a side issue - I find organ 78s are usually disappointing (poorly recorded and/or too difficult to reproduce acoustically). Two records with prominent 32 ft. stops which I do find satisfying are Quentin MacLean's performance of Rhapsody in Blue (UK Columbia DX 116, 1930) and Fernando Germani's Mozart: Fantasia in F minor (HMV C7922/7933, 1952).


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 Post subject: Re: Status of Douglas Fitzpatrick‟s Gramophone
PostPosted: Tue Nov 14, 2017 3:50 am 
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Victor III
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F. Depero, "Grammofono", 1923.
Joined: Thu Feb 24, 2011 4:19 am
Posts: 551
Location: Italy
Orchorsol wrote:
Percy Wilson reported that the Fitzpatrick instrument was able to "track" (quote) a 30 Hz test cut accurately, but whether and how it actually delivered that frequency is unknown!

I also seriously doubt about it. "Track" doesn't mean "deliver within -3 dB". Horns that really go down to 30 Hz are gigantic, they basically take entire room walls. In respectable horns like the Klipsch Scala, there is nothing to be really heard below 70 Hz, which is at first shocking considered the size of the cabinet. They also should be rationally placed at corners or along walls and floorstanding, not "in the middle of air" like Fitzpatrick's. I'm sure that Fitzpatrick's horn deliver a marvellous sound, but it's simply not rationally designed and placed with the aim of delivering the lowest possible pitch.

I also second your comment about subjective listening. I remember reading a specialised book on organ stops, where it was explained that a specific organ stop (I'm sorry I can't remember the name) doesn't really reach lower pitches, but below a specific key "simulates" them with a pair of overtones that, together, are percieved by the human brain as the pedal note.

I think I don't have organ 78s but, for some reason, I figure that recording an organ acoustically would be a nightmare. (the only record that I surely own is Diamond Record - possibly "Rollo Maitland on the Midlosh Pipe Organ" - and it's quite awful, but I don't know wether it was acoustically or electrically recorded).


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 Post subject: Re: Status of Douglas Fitzpatrick‟s Gramophone
PostPosted: Tue Nov 14, 2017 5:30 am 
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Victor III
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Posts: 574
Location: near Utopia, UK
Marco Gilardetti wrote:
I remember reading a specialised book on organ stops, where it was explained that a specific organ stop (I'm sorry I can't remember the name) doesn't really reach lower pitches, but below a specific key "simulates" them with a pair of overtones that, together, are percieved by the human brain as the pedal note.

In the UK those would be called "resultant", "acoustic" or "harmonic" stops, always in the pedal department. Bottom C of a true 32' stop is 16 Hz; they synthesize that pitch usually by sounding the octave and the fifth above that (i.e. the first two frequencies of the harmonic series).

Apologies for causing a bit of thread drift! Back on topic, the ability to track a very low frequency with a fibre needle, whether it is delivered at any appreciable volume to the air or not, does have some significance - with a less well-designed horn (being an impedance matching apparatus as you have said Marco) the needle would be likely to chatter in the groove or its tip would break down prematurely, since the energy offered by the groove from the motor cannot be coupled to the air efficiently. Wilson referred to successful tracking of a "high amplitude cut" at 30 Hz and the groove excursion must have been quite extreme! Everything must be in balance, soundbox compliance and horn design, with no undue resonances or damping effects at any frequencies, otherwise the needle would experience resistance or excitation. An inexpert attempt to explain, however, please note!

It's also worth pointing out that in its original position in the corner of Fitzpatrick's listening room, we think two walls and the ceiling acted as extensions of the horn.


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 Post subject: Re: Status of Douglas Fitzpatrick‟s Gramophone
PostPosted: Wed Nov 15, 2017 6:33 pm 
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Victor II
Joined: Tue Jun 30, 2009 8:17 am
Posts: 298
Graham, thank you for the update. I am also partial to the directional sound and presence of the oversize horn. Although in company I always play my 78’s on an electrical setup with corner reflex speakers, so “More listeners are thus enabled to have an identical experience.”
I imagine there are so many factors involved in getting the DF to perform at it’s best. Just the positioning and room size would have so many variables. The energy needed to truthfully reproduce low registers would be a struggle for any acoustic soundbox. The spring motor surly would not be able to provide the solid energy to drive a horn of that size. The 301 on the other hand would have been a far better setup. A heavy spindle clamp is worth a try, I'm sure it would make significant improvements.


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 Post subject: Re: Status of Douglas Fitzpatrick‟s Gramophone
PostPosted: Wed Nov 15, 2017 8:56 pm 
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Victor IV
Joined: Sat Jul 09, 2016 7:12 pm
Posts: 1098
Marco Gilardetti wrote:
Horns that really go down to 30 Hz are gigantic, they basically take entire room walls.


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The monster-size Orthophonic horns relied on supplemental electrical amplification, using a Western Electric driver. According to Welch & Reed's analysis of "The Theory of Matched Impedance," (in "From Tinfoil to Stereo") a different style sound box should have been used for each size of Orthophonic horn Victor produced, but Victor opted for the same one to be installed on all of the models--from the Consolette to the VE-10-50. I'm wondering if a sound box equipped with a larger than normal (aluminum or similar material) diaphragm would enhance the Fitzpatrick gramophone's sound quality. It would be fun to experiment.

OrthoFan


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 Post subject: Re: Status of Douglas Fitzpatrick‟s Gramophone
PostPosted: Wed Nov 15, 2017 11:12 pm 
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Victor II
Joined: Tue Jun 30, 2009 8:17 am
Posts: 298
OrthoFan, excellent article and yes the Orthophonic range should have had different soundboxes for each model or at lease a more "tunable" soundbox like the Expert and EMG 4-spring soundboxes.
As for different size of diaphragm, I believe the Orthophonic soundboxes have an optimal size. Anything larger or smaller would have limited it's range.
For example the HMV 4 soundbox with it's larger mica diameter seems excellent for reproducing pre-electrical 78's but only because of their and it's, narrower frequency range. It's less, self noise also contributes to this illusion.
The smaller Exhibition soundbox has a wider frequency range but it's a lot noisier. I believe that is the compromise, very similar to microphone diaphragm restrictions.


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