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Gramophone amplifier of 1930 - two valves (tubes)
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- čas přidán 24. 04. 2018
- Here we are, pursuing our goal of playing vintage audio through contemporary equipment. In this case, a 1929 disc by Frank Braidwood (‘The Cowboy Baritone”) while he was over in the U.K., taking a break from making the Western films in which he was very popular. The video is, hopefully, self-explanatory; but we must give our great thanks to www.americanradiohistory.com for their superb collection of British vintage wireless magazines - a veritable gold-mine of information. Of course, their vast archive of U.S. magazines is stupendous, and it would take a lifetime to read & study them. Also, we found it extremely difficult to record a disc from a loudspeaker. In fact, if we had known how difficult it was going to be, we probably would never have made this video! If one wishes to demonstrate a mechanical (acoustic) gramophone, there is no option but to use a microphone. Still, it would seem that any replayed audio recorded ‘second-hand’ by a microphone is always pretty crummy. This means (a) recordings made from mechanical machines are never truly representative of the quality of the actual performance of the machine; and (b) recordings made from a loudspeaker are even worse! Also, it seems that CZcams may sometimes change the sound track to some extent, during the processing of the video. Anyhow, to make amends, we have also transferred the Frank Braidwood side “Tell Me More About Love” (Piccadilly 394) using modern methods. The disc is at the top of this page: normanfield.com... - .
Fantastic volume and quality from a couple of 2v triodes and a cone speaker. Very much enjoyed this.
That was fine Mr. Field. With your white lab coat that has your name on it, your tie and the subtle humor (or "humour") you would make a splendid professor. I could listen to you for hours!
You're very kind to send your approval - many thanks! We're plotting a short & simple Christmas 2019 project. It should be quite straightforward, & will help with the playing of some, if not all, vertically-cut discs. In the meantime, best wishes in the run-up to Xmas. Cheers, Norman.
I have a pick up like that, 2 actually. Well 2 that you can attach to your mechanical phonograph and play an electrical signal through your radio set. One day it will all get restored, it is all on my bucket list. I wish I had 1/1000 the knowledge you have. Oh, well. In my next life maybe.
I had an RE-45 Victor radio / phono that had the horseshoe magnetic pickup that was open when I got it. I found that taking a small value ceramic cap, then charging it up to about 4.5 KV using the focus voltage of a common era crt type color tv, then dumping this high voltage/low current across the windings, gave an internal arc that welded the open. I used it for several years before selling the unit, so was a reliable fix. The volume level was probably somewhat compromised, but had sufficient audio volume and good tone. Upon relaying this story to an tech who had worked in the 30's, the radio, he referred to it as a "fish mouth" by the techs who were working in his area at the time. A pic of the RE-45 shows a catfish mouth shaped trim surrounding the frequency readout. This occurred in the mid '80s, so I don't remember the size of the cap, but was probably in the 250 pf @ 6KV area, and can't remember if I chanced upon this repair, or heard about it from somewhere else.
That's a fascinating 'fix', Edmund! Am sure it would work more often than not - even if the arc bridges a few turns, it wouldn't matter on a 2000+ Ohm winding! Cheers, Norman.
Utterly enjoyable! Keep up the good work! :D
Thanks, Ciel, for writing. We haven't done so much on youtube lately, but are still 100% dedicated to vntage audio. Not just the technical side, but the MUSIC also - which it was all about. 😀 Very best wishes to you and your family. Cheers, Norman.
All I can say is "Brilliant" it's so refreshing to see someone so passionate and knowledgeable about a very imprtant part of history. Many Thanks.
14:37 this record player is a miracle, it removes the user in a flash when the stylus touched the record.
Lol, it's a jump cut
Some people were listen radio putting a headphone side to an acoustic record player's "pickup" to use its "loudspeaker"
As I've said before: I know nothing, but find your presentations fascinating and this is no exception! Thank you!
Thanks for writing again. We've strayed a bit from 1920s hot jazz music lately - next time, we'll have to use old gear to play a classic jazz record... Cheers, Norman.
Yes please!
Hi Norman
Amazing projects and love your approach. As a collector and restorer of audio - amazing.
Warm regards
Richard
Many thanks, Richard. It's fun to tread the ancient path that early radio enthusiasts followed. In fact, some of the old bits & pieces one can get today, are probably cheaper that they were 80 - 90 years ago... as long as they still work. 8^) Cheers, Norman.
I recently purchased a 2 tube amplifier, that looks like it would go perfectly with my 1 tube radio - all I would think @ 1920-23. Sadly no gramophones involved.
As always, a great video Norman! You're a master of clear and entertaining communication...it's a good day when a Norman Field video comes online!
Someday, when you find yourself with nothing better to do, I'd enjoy seeing a video of your record collection that shows us some of the highlights; oldest, rarest, most valuable, strangest history, your favorite, etc.
Superb! I love your compilations. The material, the edits, the quips. Well done, and thank you :-)
Thank you very much. Hoping to put up more such videos, tying together vintage music & old-time electrical gear. Perhaps a new trend will start? I don't think so, but what the heck. 8^) Cheers, Norman.
Another great video. I did get a chance to listen to the mp3 version and it sounded great. Thank you for sharing.
Hi Paul. Thanks a lot. Yes, I finally got the link up & running again. No-one seems to know who made the gear that Piccadilly/Metropole used for British recordings, but it was darn good, & considering that Piccadilly was a cheap label at 1/6d (7.5 pence , FWIW), their pressings were pretty smooth too. Cheers, Norman.
An excellent video,wonderfully presented.Thanks Norman.
Kind of you to write - many thanks. The gear already works a bit better as I tinker with it... the speaker 'baffle board', for instance, was not rigid enough. It was only 6mm MDF - but please don't tell anybody! 8^) Tomorrow, am going out to get some serious 7-ply wood... Cheers, Norman.
Hi Norman!
Thank you very much again for another fantastic video. Very informative and a pleasure to watch. Thank you also for the brilliant music you select. Can’t wait for the next video.
Best regards,
Gavin
Glad you liked it. Yes - the old-time music is great, and we have neglected it a bit recently - but will try to make amends soon. Cheers, Norman.
Thanks Norm.
You're welcome - thanks for writing! Cheers, Norman.
Would love to also hear a transfer of the theatre disc-the track is “Gaiety” by Dominico Savino.
Very nice work there, I love the simple 20's amplifier designs. Might have to try something similar with a friends 1923 RCA Radioa amplifier, once we figure out replacements for the rare and flawed design WD11 tubes.
Excellent stuff.. Most over my head, but really enjoyable video..
Thanks Norman. Good job of construction there! You'd be hard pushed to achieve the same sound output levels if using only two bipolar transistors and a handful of components! The harmonic content of avalve amplifuer is also 'warmer' than that if a transistor amplifier.That valve amplifier is running in Class A, so the maximum theoretical efficiency of the output valve, neglecting grid bias, filament power and filament dropper resistor losses, will be 25%. Output power will be closer to 180mW, at best. Those moving iron loudspeakers were rumoured to be more efficient than modern 'hi-fi' moving coil speakers, which are often only about 1% to 2% efficient at converting electrical power to sound power. But they sacrificed sound quality in favour of efficiency. I cannot verify that claim, because I’ve only ever owned one of them, and threw it away, not knowing what it was. Blame youth and impatience for that! The interstate coupling transformer idea was still used in 1960's amplifiers, until people remembered that bipolar transistors are current-driven, not voltage-driven as valves are. That's when expensive transformers wee replaced by cheap resistors and capacitors. The transformer was often wired as an auto transformer as a way of cutting size and cost. As you say, wiring them different ways around gives different sound qualities, but that's because of varying degrees of mismatch of valve impedance. A change to input impedance will also affect output impedance, and thus the sound and efficiency of the output. Moving coil speakers were often ignored because they required an additional output valve anode impedance matching transformer, so adding to size, weight, and above all, cost to the manufacturer and consumer. Try using loops of wire and a washer under those screw terminals; military equipment often came with pre-formed loops on the end of connectors, especially with headphones. 73/g0mrb.
Add two transformers to the transistor circuit and you'll be amazed at the output you get.
I made an amp specifically for 1920s speakers using two transformers and two transistors in push pull.
I get something like 50Vrms output into a 5K load and the current draw is under 100mA.
Do agree that tubes are better though.
Brilliant as usual, thanks!
Thanks a lot for writing! Hope to do more like this in the future. All the best to you & yours, cheers, Norman.
Great stuff norm ! Hope you do one on the BUT pick up . I have one of fitted to a hm v 521 but
Nightmare trying g to setup correctly it works better with armature from a hm v pickup ha ha !
Parlophone was brought into the EMI fold in 1938, I believe, by Columbia Graphophone when that company merged with The Gramophone Company to form Electric & Musical Industries Ltd. in that year. As for Picadilly Records, that was a label owned and operated by a little outfit called Nixa Records. In 1959 Nixa did a deal whereby they took on the PYE trademark(PYE Electrical Ltd. was keen to get into the recording industry in 1959 but had neither studios nor record processing plant. Nixa had both, but what Nixa lacked was an effective distribution network for their product. This was where PYE stepped in, they had an extensive distribution network). So Nixa became PYE/Nixa, then simply PYE in 1960 but kept an ever-resent reminder of her origins in the catalogue prefix on the 45rpm singles, 7N-xxxxx(lower-case x's represent number variances). The deal came to an end in the very late 1970s when PYE Electrical pulled out of the deal. The record company couldn't revert to its old brand-name so rebranded itself as PRT - Precision Records & Tapes Ltd. and doing a distribution deal with Polygram, but not to be absorbed into the Polygram empire, rather as a "client" label which would retain its own numbering system.
We don't know Pye in America, but from the sets I see on line and on ebay, they made some very pretty sets.
@@kfl611 That's a typical superficial response from an American. PYE were makers of top-quality consumer electronic goods, vastly superior to anything made in America. Australia's AWA and Kriesler brands are also of a quality way above that of American branded products.
@@neilforbes416 Perhaps, ha ha ha. Well I am an American. It's a brand not sold here, so we are not familiar with it.
@@kfl611 But whether you're familiar with the brand or not, your only comment was how "pretty" the device looked. There was no mention of how well it performed. It showed me clearly that you were only interested in the cosmetics, not the substance.
@@neilforbes416 Everyone knows pretty radios and record players, sound nicer than ugly ones. Like I said this is not a brand sold in America,so we are not familiar with it. I'd love to see it work and play and hear how it sounds, and see what it's special features are, and how when the vintage models sold new, how the company advertised them and 'sold' all their wonderful features. Half the fun in antique radios, to me, is looking at the old advertisements, so see how the company presented all the new and exciting wonderful features.
It's very interesting, as I fix older audio equipment (50's-60's era).... the speakers were more efficient and produced more volume per watt of power. That's decent volume for a half watt.
An excellent video, Norman. I've tried and tried to record audio from a loud speaker using a microphone and come to the conclusion the human ear takes some beating! I tend to keep the mic as close as possible to the speaker to keep the room's ambience to a minimum, and hope for the best!
Even as somebody who already runs 78 and has low powered tube amps I'm surprised at how good this sounds
Surprised by your annotation at the end, it does sound like it's clipping the hard transients but I thought that was part of the recording, I'll have to try to listen to The link I'm surprised to hear it sounds even better than that
Love seeing these projects where you build early audio using (where possible) vintage parts. Great authentic sound, though high in treble response. My experience of the PM2DX (as a detector) is that it gives higher gain than say a PM2HL, the trade off being a higher treble response. When I first saw the circuit I wondered why they didn't specify a PM1LF (or equivalent) Guess they were looking for highest possible gain using few valves. It might be worth trying an LF, or even an HL valve in the 1st stage to see what happens.
HI Paul. The original 1930 circuit was a 3-valve radiogram: HF, Detector & LF. (PM12M, PM2DX & PM252.) The PM252 was - as you know, a 'super-power' triode. Not too common & quite expensive these days! Alas, it was shot, so I had to use something else. Of course, that meant that all the impedances were wrong, so guess I was lucky that it worked at all. We'll try to trawl down another circuit that will fit the few valves we have here. Thanks for writing, and all the best. Norman.
Hi Norman, thanks for the interesting reply, would love to have seen the original in action. Not heard of the PM252, mainly come across PM2 or 220P for the output role. Saw something similar to your description in an antique shop in the 1980's. Heavily canibalised, modified & bits missing, but ridiculously expensive! Would love to have had a tinker. Here's my Collaro RC1 if you've not seen it before: czcams.com/video/yjEOV_4Q26s/video.html Need a suitable amplifier as it didn't come with one. Off camera I'm using a 1980's 'ghetto blaster' for the audio. Sure to be impedance issues, but with the graphic equaliser it doesn't sound too bad. Any idea of a date Norman? Looks 1930's, but pickup quite light (bar magnet derspite room for horseshoe) & original motor wiring plastic covered not rubber. Best regards & keep those videos coming!
great work, when i seen the diagram i thought they had made a mistake having the transformer backwards lol...
still to the next issue of the sound being captured, one thing that is missed is the sounds fidelity as its bounced off some and dampened by furniture when listening in and when recording it direct.
i have been following your hardware repairs and olde-timely remakes of electronics, brilliant man, it just also proves how far manufacturing has come in to our young generation who only see things as a throw away society :/
anyhow, best regards, m6yru
Thanks for writing. Yes, the 'crazy' connections, linking the primary to the secondary of the transformer seemed very strange to begin with. Had I realised before that they sometimes did that (though not very often) I would have made the circuit diagram show two AF chokes in series, rather than a transformer! It would have looked a lot better then. I also discovered, that when one winding of an inter-valve transformer went open circuit, they often didn't just throw it away (they were expensive, like everything else) but would use the surviving winding as an AF choke! Cheers, Norman.
Yes, that interstage 'transformer' would have had us all scratching our heads, especially as it was capacitively coupled too and had the bias voltage applied to the primary! Have you tried it without the choke altogether?
Would the drive be enough from the PM2?
BTH
British Thompson Houston - BTH - later became AEI. My first job in semiconductors was with AEI, which later became, in part, MEDL. All part of GEC., maybe the biggest manufacturing group in Great Britain. Their company contacts directory used to be as big as a phone book.
I cannot get the link to work.
Hi there - yes, sorry: I was rearranging my website & forgot that some of my YT vids link to a page on that site. I'll try to fix it later today. Cheers, Norman.
Hi John - I've reinstated the page & link & it should work now. If not, it's www.normanfield.com/index.php/music-2 Cheers, Norman.
You have discovered for yourself why miking a guitar cabinet is an art, but fortunately that means you can steal their techniques. What part of the cone the microphone is pointed at greatly affects the frequency response, for one thing. I'd imagine that warped, patched, and tortured speaker cone wasn't helping the radiation pattern any.
The distortion at the peaks sounds an awful lot like the territory guitarists like to muck about in as well. Some of it may be sag in the supply voltage, but at half a watt this probably isn't an issue.