Testing Reproducers

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TN Allen
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Testing Reproducers

Post by TN Allen »

Given the importance of the reproducer, how are/were they tested?

Listening makes sense, and perhaps a microphone at the horn's mouth connected to an oscilloscope.

In order test only the reproducers are they removed from the tonearm and set up a certain way, perhaps in a sort of tonearm that allows the reproducer and needle to play through a special recording of graduated frequencies, and the sound from the reproducer compared to the optimum test frequencies?

In addition, how are reproducers tested and adjusted to perform optimally, and to compare different reproducers?

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Inigo
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Re: Testing Reproducers

Post by Inigo »

:shock:
I do mine by ear only, using the same machine, needle and record for comparison. :?
The soundbox alone is nonsense... You must test it installed in the sound system. As one wise colleague said, each soundbox responds in different way as per the sound system on which it is installed. I have a Meltrope iii that gives a poor treble sound in my huge horn hmv194, but performs wonderfully in the smaller horn of my hmv127 and in the 101s. The impedance matching comprises the whole sound system.
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poodling around
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Re: Testing Reproducers

Post by poodling around »

Inigo wrote: Mon Jul 26, 2021 6:04 pm :shock:
I do mine by ear only, using the same machine, needle and record for comparison. :?
The soundbox alone is nonsense... You must test it installed in the sound system. As one wise colleague said, each soundbox responds in different way as per the sound system on which it is installed. I have a Meltrope iii that gives a poor treble sound in my huge horn hmv194, but performs wonderfully in the smaller horn of my hmv127 and in the 101s. The impedance matching comprises the whole sound system.
A very interesting read. I agree. After much 'swapping and changing' I have found (by ear) that my Three Muses soundbox sounds best on the HMV 101, a Meltrope iii on a HMV 102 and a Meltrope ii (with fibre needle) in the HMV 100.

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mrrgstuff
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Re: Testing Reproducers

Post by mrrgstuff »

TN Allen wrote: Mon Jul 26, 2021 2:44 pm Listening makes sense, and perhaps a microphone at the horn's mouth connected to an oscilloscope.
...
In addition, how are reproducers tested and adjusted to perform optimally, and to compare different reproducers?
Basically what I do is record the record multiple times with a mic actually inside the horn. One recording for each different reproducer or modification I want to make. I then splice the recordings together so as the record plays you can compare the differences in sound quality. It's subjective, but works well enough. I've made quite a few videos using this technique. One example is:
https://youtu.be/Me3WSV9OF9c

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Inigo
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Re: Testing Reproducers

Post by Inigo »

Very clever and illustrative test.
The voice in that recording is British vocalist Jack Plant. Typical of him that clear vocalization, vibrato sustained notes and soft but strong voice. I only had for many years one record by him, which was with Mantovani orch, singing "No souvenirs" and "Dancing is another name for love" in a Spanish dubbed copy of the original uk Decca of 1940. I loved that record and knew it by heart.
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TN Allen
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Re: Testing Reproducers

Post by TN Allen »

"Basically what I do is record the record multiple times with a mic actually inside the horn."

Your testing method is interesting and quite clever. I listened to the linked recording, the difference in reproducer sound is easily detected and informative.

Where in the horn do you locate the microphone? I assume the location my be somewhat critical, and that different locations along the sound transmission line produce changes in the sound output and recording.

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mrrgstuff
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Re: Testing Reproducers

Post by mrrgstuff »

TN Allen wrote: Fri Aug 06, 2021 7:48 am "Where in the horn do you locate the microphone? I assume the location my be somewhat critical, and that different locations along the sound transmission line produce changes in the sound output and recording.
It's a good question, and I made the following video to see/show whether position matters and how much. Basically though I am making use of the louvre slats to mount the mic:
https://youtu.be/vl1V5q5oyTA

Prior to getting the Zoom H1n I was just using the mic on my camcorder and had a mount set up so it was repeatable, but I had to make recordings at odd times to avoid outside noise! ;)

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