Victor "el-cheapo" orthophonic soundbox?

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frenchmarky
Victor I
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Victor "el-cheapo" orthophonic soundbox?

Post by frenchmarky »

I ran across a rusted-up Victor Orthophonic soundbox, but it isn't the usual portable version you see that is made of heavy potmetal. It was all rotted so I tore it apart just to look inside. Instead of being screwed together with a large ring, it is crimped around the circimference and has a totally different mounting system. It was not made to be serviced that's for damn sure. The needlebar is super cheesy, it just pivots on two pins and is held in place with a spring clip. It's obviously a portable model since it has the sound muffling cloth. Seems to be the usual metal diaphragm with the spider though (fortunately, still useable).

I was expecting it to be a later RCA model for real low budget portables perhaps, but it only says Victor Orthophonic" & "Victor Talking Machine Company" on it. Anybody know what timeframe this unit was used in? Didn't see this soundbox shown or mentioned anywhere in 'Look for the Dog', which I would have since it seems to be a non-RCA soundbox.

Related - is there any info somewhere about the chromed-out RCA acoustic soundbox I've seen on some suitcase models? It says 'RCA' with a big V on it. Was wondering what the mechanics look like on the inside of these. Are they just a cosmetically jazzed-up version of the old Orthophonic or are they totally different? How do they compare?

Thanks!

OrthoFan
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Re: Victor "el-cheapo" orthophonic soundbox?

Post by OrthoFan »

That's the sound box that was fitted to the tone arm of the VV-2-35 portable ( http://www.victor-victrola.com/2-35.htm ), seen in this video:

[youtube]http://www.youtube.com/watch?v=8D0dLWaP6NU[/youtube]

Don't know why Victor opted for this design--perhaps because of the added weight imposed on the record by the 2-35's heavier, straight tonearm. The more expensive 2-55 used the heavier conventional Orthophonic sound box, fitted with a mask.

When in good condition, these perform about as well as a standard Orthophonic sound box, but as you note, they are not repairable.

The same type of sound box, dubbed the #16, was fitted to the HMV 102 portable when it was first introduced, but it was shortly supplanted by the HMV 5a.

gramophoneshane
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Re: Victor "el-cheapo" orthophonic soundbox?

Post by gramophoneshane »

Yes, the HMV no.16 was used on the early 102s, but I think was originally offered (in the HMV range) with the model 99 portable, which like the 2-35 above, also used a straight tonearm.
Attachments
HMV model 99.jpg

OrthoFan
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Re: Victor "el-cheapo" orthophonic soundbox?

Post by OrthoFan »

Related - is there any info somewhere about the chromed-out RCA acoustic soundbox I've seen on some suitcase models? It says 'RCA' with a big V on it. Was wondering what the mechanics look like on the inside of these. Are they just a cosmetically jazzed-up version of the old Orthophonic or are they totally different? How do they compare?
You mean this?
RCA Sound Box.JPG
RCA Sound Box.JPG (18.92 KiB) Viewed 2838 times

These, I believe, were made by an outside manufacturer and fitted onto the later 1930s RCA Portable Victrolas. (A nearly identical sound box, sans the fancy logo on the mask, was used on other off brand portables of the period such as Birch and Pal.)

They were far less complex than the Orthophonic sound boxes. For one thing, they used a simple needle bar pivot--two pointed lugs, held in place by locking bolts, that pressed against the rather bulky base of the needle bar.

The diaphragm, which was clamped in place between flat, soft rubber gaskets, had a "dome" shaped center. Concentric rings were stamped into the diaphragm for added flexibility. (No spider was used.)

With the original hardened rubber gaskets in place, they sound quite shrill. Replacing the gaskets does help considerably, though they are still no match for a well restored Orthophonic sound box.

There was a post on this site, awhile back, concerning the replacement of the original diaphragm with an Orthophonic diaphragm--without the spider--you might find of interest: http://forum.talkingmachine.info/viewto ... 15&start=0

frenchmarky
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Re: Victor "el-cheapo" orthophonic soundbox?

Post by frenchmarky »

Thanks for the info. Look for the Dog just lists the 2-35 as having a #5 which is incorrect, but in the pic in the book I can see it is this skinnier, cheaper soundbox.

Sounds like that later RCA 'chrome' job is sort of like a cross between a #4 and an orthophonic, with simple bearings but a semi-ortho diaphragm. Hmm I have an extra ortho disc, maybe I could try adapting it to my #4 : )))

Note - I've looked at some modern headphone drivers, like the ones in my primo Sony headphones. It's amazing how the drivers' mylar diaphragms still look eerily similar to Victor's original orthophonic - the coil is attached to the mylar in a circular area instead of just at the center point, and the outer circumference has the flexible, angled folds. Makes me wonder if the ultimate acoustic diaphragm might be to simply to find the correct size mylar headphone diaphragm and adapt it to attach to a needlebar, since headphones are designed to be sort of all-frequency, not just a tweeter or woofer. I don't know if it was Victor that designed that disc or if it was really Bell or someone else, but it's really something that it is acoustic and 80 years old, but still has exactly the same design principles as some $200 headphones today. And these are headphones that can produce frequencies that can't even be heard by humans!

The main difference between them is that the mylars' centers are rounded, whereas the Victor disc is cone-shaped, I wonder how much effect that difference has. And of course this strong, light mylar material wasn't around in 1926.

OrthoFan
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Re: Victor "el-cheapo" orthophonic soundbox?

Post by OrthoFan »

frenchmarky wrote:
Sounds like that later RCA 'chrome' job is sort of like a cross between a #4 and an orthophonic, with simple bearings but a semi-ortho diaphragm. Hmm I have an extra ortho disc, maybe I could try adapting it to my #4 : )))

Note - I've looked at some modern headphone drivers, like the ones in my primo Sony headphones. It's amazing how the drivers' mylar diaphragms still look eerily similar to Victor's original orthophonic - the coil is attached to the mylar in a circular area instead of just at the center point, and the outer circumference has the flexible, angled folds. ...
The needle bar pivot used for the #4 sound box was more sophisticated than the one used in later (US) designs in that it still relied on ball bearings at the two pressure points between the lugs and the needle bar, itself:
Sound box pivots.JPG
Sound box pivots.JPG (40.85 KiB) Viewed 2798 times
#4 Sound Box manual -- http://www.nipperhead.com/old/vic4sb02.htm

The #4 sound box's needle bar assembly eventually made its way to the HMV versions of the Orthophonic sound box-- the 5a, and later, the 5b. Many collectors--myself included--don't feel that the HMV versions are as powerful as the earlier Orthophonic design.

----------------------------------------------------------

There was a post on this forum, awhile back, about using modern diaphragms, or diaphragm materials such as titanium, in sound boxes --

http://forum.talkingmachine.info/viewto ... &view=next

Don't know if anyone's tried this.

frenchmarky
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Re: Victor "el-cheapo" orthophonic soundbox?

Post by frenchmarky »

Cool discussion on trying new diaphragms. Maybe speaker diaphragms would be too stiff because of the power they are used for, and headphone ones would be too thin and flexible, I dunno. Maybe headphone drivers that could be driven quite loud would be the best. I know my Sonys are not near loud enough to get good volume if they were being pumped straight into a horn. Maybe Victor couldn't have used anything more hi-tech than that Duralumin back in '25, and if they'd tried to make it thinner so that it would flex more, it would probably start to tear. 80 years was a LONG time ago :0
I think I'll start investigating headphone drivers some more...

I just picked up an old 'Musette' soundbox attachment, that was made for playing a radio thru a Victrola tonearm. It is fully nickle plated and shined up like a new chrome bumper, but the innards turned out to be unfixable, so I'm going to try putting a 50mm speaker inside of it instead. It will be from a little $5 Ipod accessory that has two little speakers in it that I've ordered:
http://www.freewebs.com/piese/miniipodboxesystem.htm.
They are only slightly smaller than the Musette diameter and have suspended aluminum diaphragms. Figure it should have decent power and freq. range for my Victrolas but I'll find out when I try it. Heck the second Ipod speaker may even have possibilities as a soundbox diaphragm, it is about the right size, and is a pretty darn low-power speaker! : )
Thanks!

gregbogantz
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Re: Victor "el-cheapo" orthophonic soundbox?

Post by gregbogantz »

The physics of acoustic reproducers is COMPLETELY different from that of modern electromagnetic transducers. Using a highly compliant diaphragm of a modern design in an acoustic phono reproducer will result in a very low mechanical resonant frequency. This will produce very low output level and very poor treble response. Proper design of acoustic reproducer systems requires that the system mechanical resonance be somewhere in the middle of the audio frequency spectrum, usually around 1 to 3 kilohertz. This usually means that the diaphragm must be relatively stiff with relatively low compliance compared with modern designs. This is necessary to yield good transfer of mechanical energy from the stylus motion to acoustic sound pressure in the tonearm. Unfortunately, having the resonance in the middle of the audio band is THE reason that acoustic reproducers have a honky, midrangey sound. But it's a necessary evil to ensure good efficiency (loudness). That said, how you modify that resonance to control its sharpness (or "Q") and how you damp the response peak has lots to do with how good the system will sound. But it's all tradeoffs. Less Q and more damping will result in flatter frequency response but at the expense of loudness. There's only so much blood that you can squeeze out of that turnip, and Victor pretty much figured out a good optimum 80 years ago. I have had some success with a new design that has lower moving mass, which allows a little higher compliance which results in lower distortion and a broader frequency response, but the compliance is still low by modern standards and the mechanical resonance still has to be put in the middle of the audio band for maximum efficiency.
Collecting moss, radios and phonos in the mountains of WNC.

frenchmarky
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Re: Victor "el-cheapo" orthophonic soundbox?

Post by frenchmarky »

So while the new diaphragms would physically function, the loudness expected just wouldn't be there, makes sense. How about instead of an entirely thin diaphragm, it was just as stiff as a duralumin one, *except* the folded ring at the outer circumference was made to be a lot more flexible? I.e. a nice hard diaphragm, but the very outer ring was extremely forgiving, like modern speakers?
Or would that not be any different than the entire disc being super thin and flexible? I'm picturing what we see in modern woofers, where it is a hard paper cone that is supported by a floppy foam ring.

Here's a pic of the Musette radio adapter that I modified to use one of these little cheap chinese speakers, hooked to my VV-210. Actually these teeny speakers are just like I was describing - hard cone with flexible foam ring. I was happily surprised that it fit in there just perfect. With just a bit of foam under it, when screwed together the speaker rim seals nicely against the inner top piece. It definitely needs the hole that the wire exits from, so that it isn't pressurized on the back side of the speaker. Kind of cool to plug this into my little pocket am radio, then attach it to my 10-50's tonearm... with the greatly increased volume and bass you'd never guess you weren't listening to a good-sized speaker!

Image

gregbogantz
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Re: Victor "el-cheapo" orthophonic soundbox?

Post by gregbogantz »

The use of a stiff diaphragm or cone suspended by a very flexible surround will yield basically the same results as using a soft diaphragm or cone. The significant issue is still the mechanical resonant frequency of the moving system. The soft surround will produce too low a resonance which will yield poor efficiency.

In modern loudspeakers, especially woofers and full-range single-driver systems such as headphones, the system is designed to operate with most of the desired frequency band above the mechanical speaker driver resonance. This reduces efficiency, just as it does in the case of the acoustic reproducer. But the tradeoff is smoother frequency response above resonance which is more desirable than good efficiency. Amplifier power is cheap and easy to come by these days - speaker efficiency is usually not high on the list of priorities, especially for hifi speakers. But that is not the case with acoustic transducers - the reverse is true.

In the case of modern phono pickups, the moving stylus system is designed to have its mechanical resonance at the very top of the audio band, usually at 15kHz or higher. This produces reduced efficiency just as with modern loudspeakers, but the advantage is much smoother frequency response and much better tracking ability in the frequency band below resonance. Once again, the reduced efficiency is offset by cheap amplifier gain which is much easier to come by than trying to get smooth response and good hi frequency tracking from a phono cartridge with its resonance in the middle of the audio band.

As you can see, the physics and the design requirements of modern cartridges, earphones, and loudspeakers, i.e. all audio transducers, is MUCH different from those desirables in the acoustic recorder and reproducer technology. Using modern design criteria in all-acoustic applications is incorrect and will result in much poorer performance than provided by the original designs. That said, some improvement over early designs can be expected by slightly tweaking the original acoustic design parameters. The primary benefit can be obtained from reducing the moving mass as much as possible which allows increased compliance which results in higher accuracy, better tracking ability, and less distortion. **BUT** this must be done without significantly changing the mechanical resonant frequency which must remain approximately in the middle of the audio band in order to maximize energy transfer efficiency.
Collecting moss, radios and phonos in the mountains of WNC.

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