anyone ever work on a Harmony H-305?

[bolero]

hey I have one of these, bought it for guitar after trying another one out that sounded fantastic

this doesn't quite sound as good, I'm wondering if anyone knows about the changes they made to the H-305 circuit over the years? or any adjustments ppl have done

it is a cool little amp: 1x12 combo, 2x6V6

thx!

[echuta13]

AFAIK there were two versions of the Harmony 305 made. Look here for reference: http://lectrolab.wordpress.com/lectrolab-models/r500/

[pdf64]

Any feasible changes to the design are unlikely to make that much difference.
Of far greater significance is that the amps will likely be full of 50 year old consumable parts which are well past their expected service life (eg tubes, carbon comp resistors, electrolytic caps, speaker).
Do you want to rebuild it?
Or do you want to chase down the failed parts, then wait for the next lot to fail?
Maybe the one which sounded great was benefiting tonally from a part whose value had drifted, yours is how they're supposed to sound?
Just raising that possibility.
Pete

[bolero]

ah, interesting, I saw the thread on the R600 lectralab but didn't realize they did the H305 as well

although that is the H305A...will have to check out the diffs

here is the H305 schem on the amp

[img768]http://bolero.comyr.com/images/harmonyH ... rge%29.jpg[/img]

[img768]http://bolero.comyr.com/images/harmonyH ... rge%29.jpg[/img]

Pete I have lots of old amps that are still going strong...next time you run across some old mullard tubes that surely aren't any good, send them my way seriously that is a possibility but the amp seems pretty healthy, as is the 12" Jensen in there. I do know they changed some of the values in the circuit over time. I'll compare those schems to what's in my amp, for starters

thx guys!!

[Structo]

Hey thanks for posting the schematic.
Always good to keep documents like that.

Good luck on chasing the tone gremlins.

[Jack Hester]

Likewise. Thanks for posting the schematic and BOM. I have them saved in my Harmony amp folder.

Jack

[Structo]

I tried filtering the colors on the schematic to be black and white.

[bolero]

ah, good idea!!

is there a schematic repository we can dump this stuff in?

is schem heaven still online?

[Structo]

Yes Schematic Heaven is still there.

Bet practice is to keep and back up all the documents on your computer.

[pdf64]

I agree, the more places files are kept, the better.

I sent the schematic from my H306 to the free info society site http://www.freeinfosociety.com/electron ... hp?id=2287

I never got a response from schematic heaven when I contacted to ask if they wanted it.
Pete