: External speaker output?  ( 825 )

Hydrolastic

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External speaker output?
« : November 16, 2019, 11:23:05 AM »
Hello, The Magnavox 1ST208F if fitting in nicely. I have determined that in my living room there is a perfect spot for a external speaker. What i would like to do is an experiment and hook one up and try it. I see that there is a difference in OHMage but am wondering what this console needs. I have seen somewhere that there was a external amp needed or does it drive it from just the wire. Also there is no balance control how is that done?  I am technically skilled but have no audio experience. Maybe another question... I also am starting on getting a SAMS schematic but am confused about how that system works. i can get one from the library? Or online for a cost but how do i find one. My all thumbs search found one for 38 dollars for the amp 175 FF but mine is an AMP 175 GH is the FF schematic close enough or is it totally unrelated? What about the tuner? Fm-MPX ? Separate sams?

hermitcrab

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Re: External speaker output?
« #1 : November 16, 2019, 11:46:15 AM »
Can't help with the external speaker question... but to get a Sam's photo fact you will need to get the numbers off the various chassis stamped on in ink...so take the back off and look on the amp, tuner, etc. those will be the numbers you need to get the schematics... and will most likely be in separate folders ... because different components were introduced at different times... after you get those model numbers look in the download section on this site... they maybe already here for you to download ... or go directly to the Sam's photofact site and enter the number... they have downloadable schematics ... usually about 15 bucks , but some are not the greatest copies ...as far as the balance control... I never figured out why maggies never put a user controlled balance on their sets.... only the high dollar sets had them ... imperials, etc....the rest just got a control mounted on the amp set by the factory...
Elton

electra225

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Re: External speaker output?
« #2 : November 16, 2019, 03:07:16 PM »
The amp, tuner and MPX each have their own schematics.  Your AMP 175 is not a bi-amp, so any 8-ohm speaker you'd like to use should work fine.  There are speaker connections on the rear cover on the cabinet, marked for identification of the wires.  One wire on + and one wire on -.  A Sams will not show external speaker connections.  You will need to turn the external speaker switch to "both" so both the console speakers and the external speakers will work.  Good luck.
I don't need Google.  My wife says she knows everything.

firedome

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Re: External speaker output?
« #3 : November 16, 2019, 04:07:28 PM »
Great source for original schematics at a v reasonable price, I've used Steve for years, fast and reliable and a nice guy too:

https://stevenjohnson.com/photofact.htm

Happy Motoring! from Roger in NY

Bill

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Re: External speaker output?
« #4 : November 17, 2019, 10:00:07 AM »
I too have used Steve's schematics.  Never a problem, and I have always received a good readable schematic.

Bill


Hydrolastic

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Re: External speaker output?
« #5 : November 17, 2019, 10:10:54 AM »
Thank you, I will get them. Is there a set of rules or guidelines on the 8 vs 4 ohm speaker usage and how do they apply to vintage Magnavox's ?

TC Chris

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Re: External speaker output?
« #6 : November 17, 2019, 01:35:53 PM »
OK, I'll jump in.  The speaker impedance choice is very non-crucial with tube equipment.  4, 8, 16, all will work.  There is some effect on sound because it affects damping factor (the effect of the back-voltage your speaker generates when the voice coil moves through the magnet's field).  But most of our consoles aren't ultra-high-end devices anyway, and if the speakers sound OK when hooked up, then don't worry.  There will be no adverse effect on the equipment.

Some solid-state amps ARE picky about impedance match, mostly older ones, and mostly when the effective impedance is too low.  I think most extension-speaker options connect the additional speaker in parallel with the internal or main ones, thereby reducing the total impedance when the extension speakers are connected.

Chris Campbell