HI-FI Console Amp

[custom10]

OK I see that now thanks, also...notcied that the output transformer shows a 16ohm tap. Could I install 16ohm speakers on this amp to replace
the current 8ohm ones by changing the taps?

[martin manning]

Could I install 16ohm speakers on this amp to replace the current 8ohm ones by changing the taps?

Absolutely, but if you use the external speaker jacks look to see if there is any switching going on when an external speaker is connected.

[custom10]

There are external jacks on the back of the unit but it is the on-board console speakers that I was thinking about changing. I have some vintage jensen duax 12" 16ohm drivers. The exisitng 12" 8 ohm speakers are OK but wanted to try the jensens. Would the external jacks be in parralel with the on board speaker output wiring? when you say switching do you mean that adding speakers to the external outputs would change the overall output impedence? Also were do the speakers actually wire to on the schematic? I also need to consider the 2 3.5" teets on each side which measure about 8 ohms. They are in parrallel with the drivers with a 5uf cap between the tweets.

Thanks

[Normster]

If you haven't already done so, head over to audiokarma.org. There's a wealth of knowledge there and you may even find someone who knows about these consoles.

Vintage hi-fi is a breed unto itself. Old gear was typically under-filtered and can benefit from larger caps. The original tubes are probably better than any new production replacements you can find. Resistors and caps have probably drifted. And of course, the electrolytics are likely down-right dangerous.

Anyway, cool looking console. Good luck with the restoration. I'm sure you're gonna love it when it's done!

[martin manning]

There are external jacks on the back of the unit but it is the on-board console speakers that I was thinking about changing. I have some vintage jensen duax 12" 16ohm drivers. The exisitng 12" 8 ohm speakers are OK but wanted to try the jensens. Would the external jacks be in parralel with the on board speaker output wiring? when you say switching do you mean that adding speakers to the external outputs would change the overall output impedence? Also were do the speakers actually wire to on the schematic? I also need to consider the 2 3.5" teets on each side which measure about 8 ohms. They are in parrallel with the drivers with a 5uf cap between the tweets.

The speakers are connected to the output transformers at the taps you see on the schematic, but the speakers and the external speaker jacks are not shown. Using the external jack might take the internal speakers out of the circuit, or just parallel them with the externals, which would lower the load impedance. The 16-ohm taps may not be hooked up at all.

The 5 uF caps you mention are probably in series with the 8-ohm tweeters to form a crossover filter, around 4 kHz. I'm out of my element here, but you might risk blowing the 8-ohm tweeters if you switch to the 16-ohm taps. Ideally I think you would change all of the drivers to 16-ohm. I'm sure you can get some help with this from the audio forum Norm mentioned.

MPM

[custom10]

OK thanks checked out that site just now for the first time, lots of stuff on the hi-fi tube amp applications/systems.