The doohickey arrived, this morning! It's in very nice shape, and the coil is intact: 1880 ohms, I read. I'll hook it up to the Radiola 18, tomorrow. I think it should fit on the gooseneck of the Victor I .
----- Original Message ----- From: "Doug" <cdh...@earthlink.net> To: "Antique Phonograph List" <phono-l@oldcrank.org> Sent: Tuesday, July 05, 2005 9:21 PM Subject: Re: [Phono-L] Unusual item on eBay > One thing that we need to have clear here. In the days that these speaker > units were made, the output impedance of the rtadio was in the order > 1000-2000Ohms. That was the general impedance of headphones, horn speakers > and the early magnetic cone speakers. What they did was couple the output > tube to the phones or speaker. This device that we're talking about is > rerally a horn speaker without the horn.Your Victrola furnished the > missing > horn. Victor did this on several models of orthophonic Victrola-Radiola > combinations. > > The other thing to remember is that the output power of those old > 3-dialers > was probably not a whole watt. The output power of a modern transistor > radio, especially a large one is higher than one of the old battery sets! > Now, back to the topic of impedance. The headphones we use today ar low > impedance devices, so the voltage output of your stereo or transistor set > is > far lower than on the mid-twenties set. If you're confused, lemme make it > worse. High impedance means (in this case) high voltage, low current in > the > speaker. Low impedance means low voltage, high current. So, in order to > match the old speakers to modern outputs, you can use an output > transformer > whose secondary impedance is low (4-8 Ohms) and whose primary impedance is > 2000 Ohms or so (It isn't critical). You simply connect the low impedance > side to the transistor set, and the high impedance side to the horn > speaker, > and it will work very well. In this, you're just hooking the transformer > in > reverse, to match the spaeker to your signal source. > > Since probably the fifties or so, the Hi-Fi headphones are really little > speakers that are mounted in the ear pads, so that's why they are low > impedance units; they're just speakers. Oh, and the other thing....don't > push the old speaker units too hard. They were never made to handle much > output, and a modern stereo amplifier could blow them out pretty quickly. > remember that the 3-dialers put out less than a watt, and some of these > stereo sets could vaporize the coils in the litle ole horn speakers. (My > Fisher 800C puts out something like 35 wayys per channel). > > If you're confused, my day has been worth while! > > > > > ----- Original Message ----- > From: "Ron L'Herault" <lhera...@bu.edu> > To: "'Antique Phonograph List'" <phono-l@oldcrank.org> > Sent: Tuesday, July 05, 2005 4:51 PM > Subject: Re: [Phono-L] Unusual item on eBay > > >> Does that mean that you couldn't use the headphone jack of a portable >> player? Too bad, because that could be secreted under the closed lid of >> the >> machine. Could you use any other normal Audio output? >> >> Ron L >> >> -----Original Message----- >> From: phono-l-boun...@oldcrank.org [mailto:phono-l-boun...@oldcrank.org] >> On >> Behalf Of Dan Kj >> Sent: Tuesday, July 05, 2005 4:03 PM >> To: Antique Phonograph List >> Subject: Re: [Phono-L] Unusual item on eBay >> >> They usually had an internal resistance of between 2,000 and 4,000 ohms, >> for connection to something like a Radiola 18
