I know this could sound sacrilegious, but have you considered driving the big horn with a modern driver? By that I mean one of the current iPod style earphones, driven by your OWL, with a very airtight connection at the tonearm. This way you remove the limitations of the old Victor driver and RCA amp, which certainly will not have a very good frequency response.
I'm guessing the OWL preamp will have sufficient power to drive that earphone, and you gain efficiency with the airtight connection to the horn. However you may need to put a small modern amp in between. The current earphones are astounding in how well they reproduce low frequencies. Maybe give it a shot in the interim, while you work on getting your archaic-style setup working. Sent from my iPhone -- Peter pjfra...@mac.com > On Sep 28, 2015, at 9:40 AM, 'Ron' r...@roscotron.com [Electrola] > <electr...@yahoogroups.com> wrote: > > > > > > From: mocap...@yahoogroups.com [mailto:mocap...@yahoogroups.com] > Sent: Monday, September 28, 2015 12:38 PM > To: mocap...@yahoogroups.com > Subject: [MOCAPS-L] Victor Electrola model 10-51 record changer > > > > > > Hello everyone; > > I have some interest in the Victor 10-51 record changer, which as most of you > know is the all-electronic version of the model I own, the all-acoustic model > 10-50 Victrola, the first record changer. The 10-51 Electrola is as scarce > as hen’s teeth, so I don’t ever hope to own one. > > > > I’m particularly interested in the electronic circuitry used to drive the > horn driver, which I own. Ron L’Herault and I played around with my 10-50 by > connecting the horn driver in place of the sound box and driving the horn > driver from a 10W PA amplifier using the 70.7 volt tap on the output > transformer. The amplifier really didn’t have enough voltage to drive the > horn driver without distorting on sound peaks. So I have been searching the > literature for schematics showing how the horn driver was originally driven > from the original 10-51 amplifier. Its 1.2k ohm dc resistance leads me to > wonder if the horn driver wasn’t the plate load on a triode, or something > like that. > > > > I own a copy of the Revised and Abridged Edition of the RCA Victor Service > Data Volume 1 1923-1937 and there are two schematics for the 10-51 on page > 46A. Additionally, the index tells me that there is supplementary info on > the 10-51 on page 239A of the same manual. Unfortunately in my copy, the > pages go directly from page 238B to page 239B, skipping page 239A!!! > > > > So the primary purpose of this epistle is to ask any of you who own this > manual or another similar manual that contains info on the 10-51 to check and > see if you have page 239A, or supplementary info on the model Victor > Electrola 10-51. > > > > Also, I should explain that my purpose in these investigations is to hear > “scroll” recordings played through the giant logarithmic horn with the bass > frequencies restored. When electrical recording was introduced, recording > engineers had to reduce the bass frequencies’ amplitude by rolling off the > bass below ~300 Hz to prevent having to reduce playing time of a disc due to > the wider groove spacing needed for large low-frequency groove excursions. > When you play back one of these electrical “scroll” records acoustically, > there is no way to add a compensating bass boost in playback to cancel out > the bass rolloff used in recording. I am using a 78rpm record changer with a > GE VR1 magnetic cartridge connected to an OWL 1 restoration preamp which can > supply the required playback bass boost. My goal is to be able to play a > disc, say an organ recording with lots of nice pedal tones, first > electrically with the bass boost added back in, and then acoustically with > the original 10-50 sound box for comparison. So far the bass boost is > working fine, although the overall loudness of the electrical playback is low > compared to the acoustical playback due to amplifier/interface problems as > outlined above. It’s very important when comparing two playback methods to > have the loudness level the same for both playbacks. > > > > If anyone can supply page 239A I would greatly appreciate it. Hopefully I > will demonstrate this scheme at a future MOCAPS meeting. > > > > Best, > > Ron Roscoe > > > __._,_.___ > Posted by: "Ron" <r...@roscotron.com> > Reply via web post • Reply to sender • Reply to group • > Start a New Topic • Messages in this topic (1) > VISIT YOUR GROUP > • Privacy • Unsubscribe • Terms of Use > . > > > __,_._,___
