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So. Inspired in part by the thread in the "Tips..." subforum about playing mp3s through Victrola horns, I sprang for this gizmo on eBay, thinking it'd be great to try to adapt it for use playing mp3s. Seemed simple enough: lop off the ear-ends of a cheap set of earbuds, strip the wires, press play.

Results: mixed, but promising -- I think. Attached to my phone or laptop, there's sound, but mighty little of it. Insufficient input. Not enough juice. Down to the basement to dig out the half-forgotten JVC mini-cd system that's in the workshop. Strip a section of lamp wire, attach the JVC to the Holtzer-Cabot. Better, but still only about half the volume I'd like is coming from the Victrola.

I can't find much of anything but a few ads for the Holtzer-Cabot device online (apparently this was first marketed in 1923), so I figured I'd ask a couple questions here:

Does anyone have experience with this gadget?

The JVC deck is 30 watts, and gives, as I said, about half the volume (with the JVC cranked all the way up) that I'd hope to hear from the Victrola horn. I guess what I need to do is match the output, somehow, of a mid-'20s radio, which is the original application for this attachment. Any advice on how to go about that?

I did find a similar attachment online, made by Dictograph, that has a volume control knob on the unit. Seems like the lack of volume control might be an innate problem with getting the Holtzer-Cabot to play loudly enough?

Anyway, I asked the seller I got the attachment from for permission to use his photographs, and he was kind enough to give it. They're reproduced below (slightly cropped so as to show detail better) courtesy of eBay seller kcjons. The Dictograph item is credited in the title.

I think you need an impedance-matching transformer between your modern play-back source and this vintage transducer.


Headphones and loudspeakers of this era were high-impedance ( several thousands of ohms ) as opposed to modern Permanent Magent speakers ( 16 ohms or so ).


I'm intrigued that this gadget was made / marketed by Holtzer-Cabot... I work in a performing arts center whose home is in a 1930 Masonic Temple and Scottish Rite Cathedral, whose original fire alarm system was made by Holtzer-Cabot.

How does it work?

Victrolacollector wrote:How does it work?

It is basically a high-impedence single earphone adapted to a disc gramophone mount. It won't give you much sound from a 8 ohm output on a modern amplifier, it needs several thousand ohm source, such as the plate of an output tube. Even then, it won't have really good sound due to the nature of the earphone type. It is like the earpiece of a candlestick telephone.

Your Holtzer-Cabot driver is probably about 1200 ohms (if you look on the box, or on the instruction sheet, it may tell you.) So the impedance mismatch is significant. Jackpine Radio makes a "black box" impedance matching transformer that will dramatically improve the volume and quality of the sound. It's a bit expensive for what really amounts to nothing more than a tiny transformer in a plastic case, but it's easy to couple with a modern output device, and it works. I've used it with a number of vintage loudspeaker drivers, and even with an iphone the output was pretty good. If you google "jackpine radio," you'll find their website.

-- Grant

Ditto on the above responses. You can use the output transformer from an old tube radio. They are usually 8 ohms on one side and between one and two thousand ohms on the other. You can order one from Lafeyette or one of the other suppliers, or look on Ebay. Russie

Thank you all for explaining what the problem is! I know little (obviously) about how electronics work, and without your help I'd probably still be trying out fixes that wouldn't stand a chance of working. Dunno if I'll pursue getting this gadget to work or not -- Jackpine's Amp-Jack Classic looks pretty useful, but it would double my investment in the gizmo and tbh I don't know how often I'd actually use this thing, as I don't have a large library of mp3s. It's a cool little device, but it'll probably be on the "get to it sometime" shelf for awhile. Maybe I'll sell it on. (I don't really wanna make a Yankee Trader listing for it just yet, but if anyone's interested, shoot me a PM.)