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 Post subject: Re: Status of Douglas Fitzpatrick‟s Gramophone
PostPosted: Thu Nov 09, 2017 2:17 pm 
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Victor V
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emgcr wrote:
...

The gramophone is entirely acoustic and spring driven---nothing electrical at all---thus "feedback loops" etc are of no relevance.


Thanks for the explanation. Maybe feedback loop was not the right word, but I thought a similar effect should happen even in acoustical reproduction. Some of the (I assume) very loud sound waves from the horn should affect the diaphragm while it is already reproducing the next notes from the record, thus creating some kind of loop effect? Or make the tonearm or other parts of the gramophone vibrate? Please don't get me wrong, I think this is an amazing construction. I simply don't understand why one would put the gramophone right in front of the horn instead of somewhat to the side, where such concerns would not come into play.

Thanks again
Andreas


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 Post subject: Re: Status of Douglas Fitzpatrick‟s Gramophone
PostPosted: Thu Nov 09, 2017 7:09 pm 
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Victor II
Joined: Tue Jun 30, 2009 8:17 am
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Wonderful news. Sounds like the right people were involved in it's restoration. I can't wait to see and hear it. Is it on display and accessible to the public?.
Graham, how does it compare to your majestic oversize horns?
Bats!!! Good to see them mounted and on display. I've found all sorts of things in my horns, ping pong balls, coins, lizards, spiders, moths, even a babies dummy.


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 Post subject: Re: Status of Douglas Fitzpatrick‟s Gramophone
PostPosted: Fri Nov 10, 2017 5:13 am 
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Victor III
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F. Depero, "Grammofono", 1923.
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alang wrote:
Maybe feedback loop was not the right word, but I thought a similar effect should happen even in acoustical reproduction.

Andreas, you are of course right and there are mechanical feedbacks and mechanical resonances, just as well as there are electronic ones.

However, the most prominent effects of feedback through air (Larsen effect, steady or damped oscillations, etc.) are achieved through electronic devices when there is amplification somewhere. In a mechano-acoustical gramophone, there is no amplification anywhere, there is only impedance adaptment. So there's no new energy to be dragged from anywhere: the energy picked up from the grooves stays the same and is delivered as-is, but with more audible effects. All feedback effects are thus quite negligible and highly damped. In my opinion, the only type of gramophone that, under some conditions, could potentially build up some relevant feedback effect is the Auxetophone. But it's not the kind of gramophone used in this setup.


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 Post subject: Re: Status of Douglas Fitzpatrick‟s Gramophone
PostPosted: Fri Nov 10, 2017 8:33 am 
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Victor II
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Marco you make some important points and to answer Andreas more fully it is worth mentioning that the drawing at the top of this post is perhaps a little confusing regarding the position and level of the horn mouth versus the deck-board and turntable. The rare photograph below the drawing, taken by Trevor and Marjorie Tarring, shows the conduit above floor level which is the original design as Andy (Orchorsol) says. It is important to appreciate that this was very much an enthusiast-led experimental gramophone meaning that Douglas Fitzpatrick altered the specification and layout several times over twenty years. The present owner has continued the process, finally settling upon the optimum to his ears. The bottom segment of the horn mouth is now, once again, higher than the top of the base unit, even when the lid is closed. Quite apart from the factors mentioned by Marco, there is little interference in sound output from a "line of sight" point of view. However, your suggestion that the base unit might have been better placed to the side of the horn is logical although this might add variables and construction complications.

The owner is an extremely private person and does not like publicity of any kind, however, I shall ask him if he would mind the posting of a photograph of the gramophone in its fully restored condition.


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 Post subject: Re: Status of Douglas Fitzpatrick‟s Gramophone
PostPosted: Fri Nov 10, 2017 10:49 am 
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Victor III
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F. Depero, "Grammofono", 1923.
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Location: Italy
emgcr wrote:
The owner is an extremely private person and does not like publicity of any kind, however, I shall ask him if he would mind the posting of a photograph of the gramophone in its fully restored condition.

I can understand that; however I am also curious to see the final setup of the gramophone and the horn, should the owner allow a picture to be posted.

The note about the flat oil surface at the bottom of the curve was interesting, I wish I could have assisted to the experiments and hear if it was more or less "placebo", or if indeed there was a perceptible effect. Surely, plano-reflex arms deliver a terrific sound! (And they also look soooo stylish!)


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 Post subject: Re: Status of Douglas Fitzpatrick‟s Gramophone
PostPosted: Fri Nov 10, 2017 10:56 am 
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Victor III
Joined: Mon May 13, 2013 2:04 pm
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emgcr wrote:
This gramophone has now been beautifully and expertly restored and lives in a special building constructed to house it. Every detail has been attended to and the result, both visually and acoustically, is most impressive.

The reason that performance previously was less than ideal turned out to be that three bats had crawled up into the smallest part of the horn and died, completely blocking the conduit where they could not be seen from either end, with rather deleterious effects on sound output. In fact, it was really amazing that any sound was heard at all !



The gramophone is entirely acoustic and spring driven---nothing electrical at all---thus "feedback loops" etc are of no relevance.


I once "restored " an EMG belonging to the Gramophone Exchange in Betterton Street , London , the gramophone made no audible sound at all ! after getting it to my workshop I discovered the U tube was full of extremely viscous treacle like liquid which was totally damping the sound and which I removed , on examination the liquid proved to be paper balls dissolved in what smelt like coffee ! The machine was on display in the shop window and I concluded that it was used as target practice for paper and had coffee poured inside it ! Sounded wonderful after removal


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 Post subject: Re: Status of Douglas Fitzpatrick‟s Gramophone
PostPosted: Fri Nov 10, 2017 11:06 am 
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Victor IV
Joined: Sat Jul 09, 2016 7:12 pm
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emgcr wrote:
... The rare photograph below the drawing, taken by Trevor and Marjorie Tarring, shows the conduit above floor level which is the original design as Andy (Orchorsol) says. ...


Attachment:
Capture.JPG
Capture.JPG [ 49.6 KiB | Viewed 139 times ]


That makes a lot more sense to me, in terms of its impact on the overall sound quality.

In the modified (1977) design, I believe the pipe which ran from the base of the tonearm and under the floor was not tapered. I've often wondered if that would have impacted the performance, or caused some distortion.

OrthoFan


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 Post subject: Re: Status of Douglas Fitzpatrick‟s Gramophone
PostPosted: Fri Nov 10, 2017 12:05 pm 
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Victor VI
I have good days...this might not be one of them
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Marco Gilardetti wrote:
emgcr wrote:
The owner is an extremely private person and does not like publicity of any kind, however, I shall ask him if he would mind the posting of a photograph of the gramophone in its fully restored condition.

I can understand that; however I am also curious to see the final setup of the gramophone and the horn, should the owner allow a picture to be posted.

The note about the flat oil surface at the bottom of the curve was interesting, I wish I could have assisted to the experiments and hear if it was more or less "placebo", or if indeed there was a perceptible effect. Surely, plano-reflex arms deliver a terrific sound! (And they also look soooo stylish!)


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.


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 Post subject: Re: Status of Douglas Fitzpatrick‟s Gramophone
PostPosted: Fri Nov 10, 2017 1:24 pm 
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Victor V
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Thanks you very much Marco and emgcr for these detailed explanations. I just sometimes get caught up in details like that and it drives me crazy :oops:

Thanks again
Andreas


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 Post subject: Re: Status of Douglas Fitzpatrick‟s Gramophone
PostPosted: Fri Nov 10, 2017 8:19 pm 
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Victor II
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OrthoFan wrote:

In the modified (1977) design, I believe the pipe which ran from the base of the tonearm and under the floor was not tapered. I've often wondered if that would have impacted the performance, or caused some distortion.

"OrthoFan"


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 ?

https://www.youtube.com/watch?v=iUL86UQs5xc

The parallel-sided pipe in the DF gramophone was made from copper and, from memory, of a smaller diameter than the outlet from the tonearm thus forming an unhelpful constriction---not a good idea !


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