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Orchorsol wrote:

poodling around wrote:

Orchorsol wrote:Some of us still use the HMV DB 4037 gliding tone test record, and other discs in that series, when tuning soundboxes! One side of the scale is specifically for that record.

Very interesting indeed.

I would watch a video of this taking place if there are any.

Thanks Orchorsol.

There's nothing scientific or specific about using it - just subjectively listening for any peaks and troughs in the response, along with listening to various familiar records of music. I can certainly upload the gliding tone record to YouTube though, if you'd still like to hear it!

Yes, it would be great to see and hear !

I have no gliding freq record, but happen to own a record with a song made for advertising a certain brand in Spain, in the early forties. It's one sided. The other side has a strong signal with a constant frequency. Once I used it as a gliding freq record, on my hmv194 gramophone, carrying the speed gradually from very slow to very fast. I observed certain strong peak in the mid-bass register, as kind of a resonant frequency for three reentrant horn. That noted sounded incredibly strong! Since then I've been thinking about it, how to muffle down that resonance. I've thought about filling the space between the horn and the cabinet with sand, or using polyurethane foam spray to cover the outer surface of the horn, of even using wooden sticks or pieces as buttresses, placed between the horn sides and the cabinet, to cut the big horn panels fixing a point at the center so to kill that resonance. It's in the note given by the horn panels when thumped with a hand...

poodling around wrote:Yes, it would be great to see and hear !

Here it is: https://www.youtube.com/watch?v=wqDRQ9W2ZEw

Could you show us a photo of the record under a strong light so we're can see the groove pattern? It must be curious... Thanks!

Orchorsol wrote:

poodling around wrote:Yes, it would be great to see and hear !

Here it is: https://www.youtube.com/watch?v=wqDRQ9W2ZEw

Fascinating ! It was really good of you to upload this so quickly and appreciated.

I have (I think) a similar record in my collection - and to be honest I have always wondered what it was !

Absolutely fascinating !

All I need know is a Record Groove Indicator maybe .........

Hi there, I have had copies of the Decca record in the past, but given them away, as I not a sound expert! There is a PARLOPHONE GLIDING TONE RECORD that I have never seen. Someone must have a copy...? It is supposed to be very helpful regarding checking frequencies of machines.
I too have a couple of SINGLE SIDED H.M.V. (I think) records of the late 1930s. There is a long spiral groove on the back with a very strong deep resonant note, so resonant that any normal soundbox is "buzzing" when it is placed in the groove. I cannot remember exactly where I put them, but if I come across either, I will place a picture of the groove on the forum later.

Inigo wrote:Could you show us a photo of the record under a strong light so we're can see the groove pattern? It must be curious... Thanks!

Not particularly!

Here is my Columbia Constant Tone Frequency Record.
The picture of the grooves is a collage of images using a digital microscope.

The discussion on this thread reminded that I have a set of frequency records, from Decca (4) and from HMV (5). Photos of some of them are below. I only played these records once or twice, out of interest in quantifying the spectral limits of some of my gramophones.