Replacing leaky capacitors in the signal path can definitely change the sound in unpleasant ways. The old leaky ones would likely ‘brown’ out the sound a bit, as the DC they let pass would cause the downstream gain stages to bias hotter (towards grid-limited clipping), and maybe reduce gain a bit.
Drifted resistors are an easy one to suss out because you can simply measure them once removed to see how far they’ve gone.
I imagine the speaker is hardwired straight to the output transformer, but you could desolder it and rig up a temporary jack to try a different speaker. Really old ceramics don’t often hold up well with time (but YMMV).
Harmony
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Re: Harmony
Clarry commented the the bias was way off; like twice what it should be. And I was just thinking about a lug to jack socket lead to try different speakers.RectifiedAmps wrote: ↑Sat Nov 27, 2021 10:03 am Replacing leaky capacitors in the signal path can definitely change the sound in unpleasant ways. The old leaky ones would likely ‘brown’ out the sound a bit, as the DC they let pass would cause the downstream gain stages to bias hotter (towards grid-limited clipping), and maybe reduce gain a bit.
Drifted resistors are an easy one to suss out because you can simply measure them once removed to see how far they’ve gone.
I imagine the speaker is hardwired straight to the output transformer, but you could desolder it and rig up a temporary jack to try a different speaker. Really old ceramics don’t often hold up well with time (but YMMV).
Beyond a critical point within a finite space, freedom diminishes as numbers increase. This is as true of humans as it is of gas molecules in a sealed flask. The human question is not how many can possibly survive within the system, but what kind of existence is possible for those who so survive.
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Re: Harmony
Cool, thanks! That's my baby...RectifiedAmps wrote: ↑Sat Nov 27, 2021 10:07 am This may be of interest too:
https://oldamps.weebly.com/harmony-h307x.html
Beyond a critical point within a finite space, freedom diminishes as numbers increase. This is as true of humans as it is of gas molecules in a sealed flask. The human question is not how many can possibly survive within the system, but what kind of existence is possible for those who so survive.
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Re: Harmony
Haven't been able to sort a cable for speaker swapping yet but I replaced the 12AX7 with a 5751. It improved things considerably. I'm reasonably sure the remaining harshness is the speaker breaking up.
But regardless, the harshness can be controlled just by turning it down a bit.
But regardless, the harshness can be controlled just by turning it down a bit.
Beyond a critical point within a finite space, freedom diminishes as numbers increase. This is as true of humans as it is of gas molecules in a sealed flask. The human question is not how many can possibly survive within the system, but what kind of existence is possible for those who so survive.
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Re: Harmony
Good to hear the sound is coming back, those speakers Harmony used were not always the best, my H400A I swapped out the stock for a 60s Jensen and the Valco made 8148 I found a 60s speaker to fit that had the same output tranny on the speaker basket. That is the one Ryan recapped for me and did a great ob.
I asked over at the Harmony forum but no one had any info but did provide a blow up of the schematic Rectified Amps linked, it may be of use
harmony-h307x-2_orig by Laurie Franks, on Flickr
I asked over at the Harmony forum but no one had any info but did provide a blow up of the schematic Rectified Amps linked, it may be of use
harmony-h307x-2_orig by Laurie Franks, on Flickr
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Re: Harmony
Just took the Harmony back to its previous owner for an assessment. He pluggd in a LPJ with single humbucker (You're not the only one, Grant) and proceeded to make it sound wonderful.
I took note of his settings which were different to what I'd been doing, but I got what I was looking for; the amp's just fine. Stop fussing and learn to play it!
I took note of his settings which were different to what I'd been doing, but I got what I was looking for; the amp's just fine. Stop fussing and learn to play it!
Beyond a critical point within a finite space, freedom diminishes as numbers increase. This is as true of humans as it is of gas molecules in a sealed flask. The human question is not how many can possibly survive within the system, but what kind of existence is possible for those who so survive.