Awesome sound out of 'Phones/No sound from Speakers

[Neuronal]

Almost there! So I finished the SEX build, all the resistances and voltages were spot on, and so I tried to listen to music. Sounds absolutely amazing through headphones, but I can't get music to play through speakers. When I hook up 8 ohm speakers via zip wire to the binding posts, I can still insert headphones into the headphone jack and hear music (which the manual says I am not supposed to be able to do). Also when I take a continuity meter, it seems like all of the binding post terminals are continuous with each other, which seems wrong to me. I think something is up with the headphone jack (I'm not sure I understand how the signal switches from the headphones to the speakers), although all the wiring traces back OK and looks fine. I don't hear anything from the speakers - no noise, no hiss, no nothing. Thanks for all the advice so far - I promise once this last problem gets solved I will leave you all to enjoying the music!!

Bob D.

 

[Dyna Saur]

What kind of meter are you using for measuring the resistance?  The speaker secondary outputs  will measure as being in the  "fraction of an ohm" range, and the "common" side (black posts) is grounded, so all 4 of the speaker binding posts will appear to be "continuous" (shorted) unless your meter / DVM has a low-ohms range, in which case they should show about  an ohm or slightly less from red to black.  If indeed they were shorted, the sound in the headphones would be non-existant or very low and muffled at best.

Since you do have good  sound in the headphones, it would appear that everything is working properly at least up to the headphone jack.  That would leave as being "suspect", the wiring between the headphone jack, and the speaker binding posts. Double check the wiring between the HP jack and the binding posts for correct connections, and for solder joints. 

Hopefully that should fix it!

(I've built two of these amps, one with the HP jack, C4AS boards,  iron and cap upgrade and the other  one  as bare-bones "basic" without  the HP jack, OPT  8 ohms secondary connected  direct to the binding posts, for speaker-only usage. (Headphones could be connected via a banana plug to 1/4 inch stereo jack adapter, if required)

/ed B in NC

 

[Neuronal]

Got it (I think)! Looks like I cross-wired at the binding posts (2 grounds to one channel, 2 signals to the other) - rookie rookie rookie. Thanks, Dyna Saur, for the heads-up on that. I'll post back when I get tunes flowing from the rig!!!
bd

 

[Neuronal]

That did it!!!!! SEX is delivering me Inara George as we speak. Thanks so much to all for all of your help - I guess I'll be posting next when I am brave enough to attempt a Foreplay! Now all I need to figure out is: how am I going to be able to convince myself to turn this thing off and go to bed? - I may stay up all night listening to tunes :>

 

[Maxwell_E]

That tends to happen. I find comfort in the low orange glow of the tubes, all the other lights off. It's like a night-light, really.