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As I remarked in my previous reply, the Chromogram's performance was vastly improved with a Meltrope soundbox, so I am not surprised that one with the original soundbox was out performed by an HMV511. Another comparison which the video failed to mention is that the HMV511 cost three times as much as the Chromogram when new.

epigramophone wrote:As I remarked in my previous reply, the Chromogram's performance was vastly improved with a Meltrope soundbox, so I am not surprised that one with the original soundbox was out performed by an HMV511. Another comparison which the video failed to mention is that the HMV511 cost three times as much as the Chromogram when new.

Many thanks. One thing I noted about the video is that the narrator, though he states that the Chromogram's sound box is "original," doesn't qualify this. Original as in "as-found/semi-frozen"? The HMV #4 sound box does sound as if it had been carefully restored, so, in a way, this is an apples and oranges type comparison.

As you note, there was a substantial cost difference between the two models, which would imply a substantial difference in build quality--the materials used to make the cabinets and horns, etc..

A more careful comparison, I think, would have involved the swapping of the sound boxes (using an adaptor) to see how each one performed on both gramophones. I also would have liked to hear what the Chromogram sounded like with a Meltrope sound box. Along this line, I fitted a restored Meltrope sound box, using an adapter, to the tonearm of a Credenza I once owned. The result was very similar to the (restored) Orthophonic sound box, in terms of bass response and range, though it was not quite as full sounding, and pumped out more hiss and surface noise.

OrthoFan

OrthoFan wrote:There's an interesting video comparing the Micro Perophone Chromogram to the more conventional HMV 511, with (what I found to be) surprising results -- https://www.youtube.com/watch?v=hV8sMw-Q21I Based on what I heard, the 511 has a fuller sound and broader range.

OrthoFan

Agreed---511 is the clear winner, to my ears. Sounds like it's reproducing more content in the upper partials of the harmonic series, thus accounting for the fuller tone quality.

OrthoFan wrote:

epigramophone wrote:As I remarked in my previous reply, the Chromogram's performance was vastly improved with a Meltrope soundbox, so I am not surprised that one with the original soundbox was out performed by an HMV511. Another comparison which the video failed to mention is that the HMV511 cost three times as much as the Chromogram when new.

Many thanks. One thing I noted about the video is that the narrator, though he states that the Chromogram's sound box is "original," doesn't qualify this. Original as in "as-found/semi-frozen"? The HMV #4 sound box does sound as if it had been carefully restored, so, in a way, this is an apples and oranges type comparison.

As you note, there was a substantial cost difference between the two models, which would imply a substantial difference in build quality--the materials used to make the cabinets and horns, etc..

A more careful comparison, I think, would have involved the swapping of the sound boxes (using an adaptor) to see how each one performed on both gramophones. I also would have liked to hear what the Chromogram sounded like with a Meltrope sound box. Along this line, I fitted a restored Meltrope sound box, using an adapter, to the tonearm of a Credenza I once owned. The result was very similar to the (restored) Orthophonic sound box, in terms of bass response and range, though it was not quite as full sounding, and pumped out more hiss and surface noise.

OrthoFan

In this video I think "original" meant that the soundbox was original to the machine, i.e. a Micro-Perophone, not that it was in original condition.
Even if the original owner had invested 12/6d in a Meltrope soundbox, the cost of the Chromogram would still have been one third of the HMV511.
Much of the additional cost of the HMV comprised the 4-spring motor, the gold plated fittings and the name inside the lid.

OrthoFan wrote:There's an interesting video comparing the Micro Perophone Chromogram to the more conventional HMV 511, with (what I found to be) surprising results -- https://www.youtube.com/watch?v=hV8sMw-Q21I Based on what I heard, the 511 has a fuller sound and broader range.
OrthoFan

The HMV sounds better and two machines look similar but the similarities end with the looks.
The cabinet of the HMV is larger in every dimension and the volume therefore is nearly twice that of the MP23. Hence the sound volume and lower range are fuller as would be expected.

I finally got the MP3 Player up and running and the sound with an HMV #5B soundbox was very disappointing. Not great volume and lacking bass but clear, sweet and detailed.
I then tried with a Decca soundbox, Meltrop clone using Andy's Burmese thorn needles which is my go to setup for getting a punchy sound. Also very disappointing and buzzy.
Finally I tried with the original soundbox that came with the machine and the horn came to life.
I played a Paul Robeson song and his voice managed to get the side of the cabinet to vibrate.

The best of the soundboxes is a blunt weapon if its acoustic impedance deosn't match the impedance of the horn. This experience confirms once more this golden rule.

Marco Gilardetti wrote:The best of the soundboxes is a blunt weapon if its acoustic impedance deosn't match the impedance of the horn. This experience confirms once more this golden rule.

Even after googling acoustic impedance I still don't know what it means.
Dictionary
acoustic impedance
noun PHYSICS
the ratio of the pressure over an imaginary surface in a sound wave to the rate of particle flow across the surface.

Daithi wrote:

Marco Gilardetti wrote:The best of the soundboxes is a blunt weapon if its acoustic impedance deosn't match the impedance of the horn. This experience confirms once more this golden rule.

Even after googling acoustic impedance I still don't know what it means.
Dictionary
acoustic impedance
noun PHYSICS
the ratio of the pressure over an imaginary surface in a sound wave to the rate of particle flow across the surface.

Tells me nothing. Pressure expressed how? What units? Rate of particle flow, same questions. What is the ideal ratio? Is it unit (one?), as in 1/1 ? This kind of non-definition is what gives physics a bad name.

Henry wrote:

Daithi wrote:

Marco Gilardetti wrote:The best of the soundboxes is a blunt weapon if its acoustic impedance deosn't match the impedance of the horn. This experience confirms once more this golden rule.

Even after googling acoustic impedance I still don't know what it means.
Dictionary
acoustic impedance
noun PHYSICS
the ratio of the pressure over an imaginary surface in a sound wave to the rate of particle flow across the surface.

Tells me nothing. Pressure expressed how? What units? Rate of particle flow, same questions. What is the ideal ratio? Is it unit (one?), as in 1/1 ? This kind of non-definition is what gives physics a bad name.

Here is the "theory of matched impedance" as published by Maxfield and Harrison -- https://archive.org/details/bstj5-3-493/mode/2up -- This is basically the science behind the Orthophonic Victrola, and a sure headache for anyone like me with a rudimentary understanding of math and physics. (In college, I learned enough to pass the exams and then went on with the rest of my life.)

OrthoFan