schematic question

[Vintage Bert]

ok first off:

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Question one:

Can you tell from this diagram if this is a mono or stereo amp? I can see the two output tubes 6Cw5 and the 12ax7 "pre" but is there anyway to tell if it is a mono or stereo output from this diagram?

Question two:

Not really sure what 600 and 400 ohm loudspeakers are? The diagram states use only with high impedance phillips loudspeakers? Can this be altered or bigger question, is this an amp worth bothering with?

 

[MexicoMiike]

It's mono - there is only a single phono in, a single aux in and a single speaker out.

The patent dates also pretty much place it prior to stereo records becoming readily available.

As far as whether it's worth fooling with - that's a personal thing. If you think it's cool, heck, why not?

 

[Lavane]

Nothing wrong with mono. I had a mono tube tuner and amp I used in my shop for years.

 

[sKiZo]

Looks to be mono ... console?

The old electro dynamic speakers had field coils attached to the baskets ...

These usually doubled as hum buckers or AC filters for the power supply and were matched specifically to a radio - no substitutions allowed. I've patched cones on quite a few as it's difficult to find replacements.

 

[cademan]

This is one of those Phillips radios which uses high impedance voice coils as there is no speaker output transformers. I don't believe that this unit uses field coil speakers according to the warning sticker.

Phillips made a later tube stereo that used four 6BQ5 tubes, two 500 ohm speakers, and no output transformers. The speakers were connected directly to the plates of the output tubes. I think they are pretty rare but imagine the people that tinkered with these and tried to use regular 8 or 4 ohm speakers with them.

 

[Vintage Bert]

Yeah I think this one is a pass. Seems rather unique, kinda cool looking but doesn't work so well, and I am thinking the speakers may be few and far between for it. The guy also has an old marconi radio, but again, not working so well.

 

[gadget73]

I'll say two channel mono. Either that or it has an internal crossover. Those 800 ohm speakers are quite difficult to come by, but you can fit a transformer to match it. I have a Norelco (Phillips) table radio that had a dead large speaker. I stuck in a 6x9 car speaker that I had along with a PA system line level transformer to match it up. Its perhaps not perfect, but its close enough for it's purpose.


The one I have runs an EL84 (6bq5) with an EL86 (6cw5) as a cathode follower to get the impedance down. It has a big coupling cap to keep DC off the speaker voice coil. Depending how this one is set up, it may use one 6CW5 per channel as a cathode follower, or it may be one driving the other like mine uses.