The PHILCO Phorum
Modern speaker for bench tests? - Printable Version

+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Philco Radio Discussions (https://philcoradio.com/phorum/forumdisplay.php?fid=5)
+--- Forum: Philco Electronic Restoration (https://philcoradio.com/phorum/forumdisplay.php?fid=8)
+--- Thread: Modern speaker for bench tests? (/showthread.php?tid=3564)


Modern speaker for bench tests? - dcastor - 08-05-2011

I apologize if this is a repeat post, I've done a search and haven't found a thread on this topic.

My question is: can a modern speaker be used to bench test one of our old chassis? I read in a post that the original speakers have high impedance and I know that mondern speakers are only 3-8 ohms, so I'm guessing no, at least not without significant modification...but I thought I'd ask the question.

And a follow-up, if not, what is the recommended source for a test speaker? buy an old radio beyond repair or are there new-old style speakers available?

Thanks,
Dave C

Re: Modern speaker for bench tests? - Radioroslyn - 08-05-2011

If you are going to spend a dollar or two pick a signal tracer. Most will have place to connect your tube type output stage to it.
Terry

Re: Modern speaker for bench tests? - AI2V - 08-06-2011

I use two bench speakers. For the early high impedance radios I use an Atwater Kent Model E2 but any of the E series works well. You can get one these, or the RCA's (Model 100?) for $50 or less. On the end of the speaker lead I've soldered a few feet of modern flexible wire with one inch pieces of large gauge bus wire that connect to the radio.

For the low impedance speaker I use a generic wide range 8" PM type. Mounted on this speaker is a generic 8 henry choke and a push-pull audio transformer. The interconnections between these are done with Anderson Power Pole connectors; they make it very simple to configure the radio output connections. For the connections to the radio I simply use clip leads with insulating hoods or tack solder.

The push-pull transformer allows me to make connections for single or push-pull outputs. For single ended I simply do not connect one side of the input. Some techies will scream "mismatch", and "Danger, Will Robinson!" but this application is for short term use and fine for the bench.