50's console speakers help

[kj]

Can anyone tell me whats up with the way these speakers are wired? What are the filter cap looking things? I'd like to use the amp and one of the speakers, but I have no idea what that would entail since I dont understand what all the wire and stuff is for. It's going to be a guitar amp!

https://picasaweb.google.com/10987886696...7240929394

Thanks! Kj

[Fritz]

I would think they're filtering DC or a low end roll off.

[Trouble]

Fritz wrote:
I would think they're filtering DC or a low end roll off.

That is exactly what they are. Crossovers http://en.wikipedia.org/wiki/Audio_crossover IIRC, capacitors are 6 db/octave. No idea if wiring them like that lowers the crossover point or increases the slope.

[kj]

Use of the word crossover doesn't seem to make sense, since they are full range speakers (there's nothing to crossover). Filter makes sense though. I still wonder why they are wired so oddly (would it help to get a better pic?). I wonder if they are wired to change the impedance? Fritz, by dc filter do you mean basically noise from the power supply? Low end roll off I understand, since it was used with an ancient turntable, and the speakers probably aren't real robust. What are the chances one speaker would work well (with one set of filter caps between the amp and the speaker). I don't really want to experiment, since I could never duplicate what's going on with them now (to restore function). kj.

[WHiiP]

"Console" speakers to me, means REALLY OLD speakers. And they look like it. I don't think they will last more than a chord or two, at least it you turning the amp up to "5" or so. YMMV.

[deckeda]

I don't know much about amps and speakers for "pro audio" (read: musical instruments) but my understanding is that things such as guitars need a "Hi-Z" input, which is somewhere in level lower than line-level, which your amp MIGHT have.

But if the amp was ONLY used for a record player it only has a phono input, with RIAA compensation EQ, which will amplify the instrument plenty (and maybe too much ...) but make the instrument sound weird too. RIAA EQ boots bass and cuts treble because records are cut just the opposite, reduced bass and higher treble.

Why only use one speaker? They're both already hooked up, leave them on that board as-is. Those filter caps, likely electrolytic, are well past their sell-by date and probably way out of spec by now.

I'm with Whiip here, if it works at all it might look like that scene in Back to the Future.





On the other hand you've got nothing to lose as the equipment isn't worth anything. Wear a helmet. Maybe some gloves. Shoes with good soles. And random kevlar.

[Filliam H. Muffman]

An old console might have been designed as a system, take one speaker out and it might not be loaded properly. Have you verified that all the tubes in the amp are in spec? My Dad used to check the tubes in their console about every three years when it started acting up, but that might have been the radio section that was more critical. I have not seen a tube tester in about 15 years. I think they removed the one out of the local Safeway lobby about 1972. :oldfogey:

[mikebw]

Removing one of multiple speakers will definitely change the impedance if they are running off the same amplified channel; this will also affect the performance of the crossover circuitry (capacitors) as they are designed to a specific impedance.

[kj]

WHiiP wrote:
"Console" speakers to me, means REALLY OLD speakers. And they look like it. I don't think they will last more than a chord or two, at least it you turning the amp up to "5" or so. YMMV.

Yeah, they are from the 50's. My wife bought the console several years ago, gutted it, and made it into a scandinavian cabinet (the wood is very pretty). I recently wondered what the guts were, and went out into the garage, and was surprised to find a really nice amp. It has 4 6V6s, two 5Y3GTs, an 12AX7, and the phono preamp has one 6AV6 (which is basically half a 12AX7). Some of the Fender Tweeds had about the same complement of tubes (not to say it's comparable).

I took all the tubes out, cleaned the contacts with deoxit, and also used it on a lot of the other contacts and stuff. The phono preamp had a phono input (imagine that), so I plugged my guitar into it and fired it up. Seriously, it sounds incredible. I've played through vintage fender tweeds, and I'm not going compare them, but this thing sounds good. The amp also has an rca input, so I could use a proper preamp and forget the phono preamp, although afaict, there's no reason to. I actually doubt the eq on the phono preamp is RIAA.

One of the 5Y3GTs is clearly damaged (the plastic peg on the bottom is broken off, etc.), so I'm going to order a matched pair to replace both. I don't know why it still works with only one of these functioning correctly. I also don't know anything about setting the bias, but as long as it sounds good, I'm not going to worry about it. I wish I could test all the tubes. But, finding that it sounds good, I put a whole evening into polishing the metal base of the amp. I couldn't do a great job, but it looks pretty sharp. Next I have to make a cabinet of some sort.

Which is why I want to use only one speaker. I would rather it be a smaller combo. The speaker wires are soldered to the amp, which make me even a little more hesitant to experiment. I'll let it sit for a while and give it some thought. Thanks, kj.

[kj]

mikebw wrote:
Removing one of multiple speakers will definitely change the impedance if they are running off the same amplified channel; this will also affect the performance of the crossover circuitry (capacitors) as they are designed to a specific impedance.

Of course. I wish I could find out more though. My other tube amp has different connectors for 4, 8 and 16 ohm speakers, so maybe there are ways to deal with it, if I knew what it was. Also, if it's 8ohms now, and one speaker was 16ohms, it would work fine (just quieter), so anyway... Thanks, kj.