Hoffman Amplifiers Tube Amplifier Forum
Other Stuff => Other Topics => Topic started by: Jack_Hester on August 27, 2012, 01:01:48 pm
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I've seen the word used often, in describing an effect or sound. I don't know what that is. What made me ask about the word came from a little something that I was doing in my shop, last Saturday morning.
I acquired a small Harmony H-400, at a reasonable price. I wasn't particularly looking for one, but just bought it. I already have an H-303B, and according to the schematics, they are virtually identical with the inputs being different. I had to replace a multi-cap in the 303B, and had bought an extra. So when I connected the 400 to the lamp limiter, and heard the very loud hum, I replaced the same in this one. That's all it took to make both really nice sounding little amps. But, with a difference. At full volume, neither are very loud. Maybe a couple of watts. But, I noticed (in the 400) that when I strummed a chord, the sound level seemed to linger, with a slight waver. It also had something of a bell ring, for lack of a better way to describe it. Was I hearing a chime in the sound? Or is there a better word for what I am hearing? Thanks for any help.
Jack
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when I strummed a chord, the sound level seemed to linger, with a slight waver. It also had something of a bell ring, for lack of a better way to describe it. Was I hearing a chime in the sound?
I think you heard "chime".
With respect, Tubenit
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It's entirely possible that the thought came to mind, because of your manner of description when you are explaining your sound clips. And, those of others. I'm not sure that I've seen descriptions of sounds, as much as here.
When I first heard it, I listened for quite a bit, as it was such a pleasant sound (meaning that I strummed often).
Yesterday afternoon, I powered up the little 303B, to compare with the 400. It does not have the same sound. Just a nice, clean little amp. So back to the 400, just to be sure I heard what I heard. I did. It 'chimed'. Only difference (by the schematics) seems to the configuration of the inputs.
Much thanks for the help.
Jack
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Jack,
Take a look at the signal chain to make sure the components are in the ballpark. If Tubenit can get an amp to chime with that broomstick, string, and washtub he calls a Tele, I'm sure you can get there with this amp!
Good luck!
Jim
ps No offense 'nit :icon_biggrin:
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Jim -
Even though there's a bit of scuffing on the outside, this amp (H-400) has all the appearance of long time storage in a clean, dry place. Thick with spider webs and original Harmony-script tubes. Once it was deemed safe from all critters that crawl, the inside of the chassis looked brand new. I left the original multi-cap attached and tied back the leads. Then, I soldered in the new one and tied it down. Other than that, I didn't take the time to confirm any component values with the schematic and meter. I replaced the rectifier tube, as it showed slightly in the red, on the grid emission test. I had a replacement that tested very good. I saved the script tube in a plastic pill bottle, to keep with the amp. The other two tested very good, also. This amp probably won't see much usage.
With the amp connected so that the 'hot' goes to the rectifier, the power switch disconnects the neutral. But, this is the quietest polarity. Rolling the plug puts the 'hot' lead to the switch, and the amp has a loud hum. My lamp limiter has an external binding post for grounding. I'm in the habit of using an external ground on these old amps that I want to keep original, with their ungrounded cord. Once I'm done with the lamps, I put a circuit breaker in the socket. When the amp is connected so that the rectifier is hot, along with an external ground to the chassis, there is a very noticeable hum in the speaker. Of course, this goes away when the power switch is turned on, and the amp is very quiet. The limiter also had a disconnect switch, so it becomes the power switch for the whole amp.
How did we survive those years, when designs like these were an acceptable risk?
Jack
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Jack,
Yeah, but I'm sure there were some casualties - which is what always drives the changes. Plus, we didn't have instant media back then with useless sacks of plasma attorneys perched like vultures....
I remember listening to my old tube Hallicrafters shortwave radio in my basement. I knew that with the polarity switch in a certain position, I couldn't put my bare feet on the floor and touch the chassis! Pavlov's Dog effect! I also have an old turn of the century engineering manual that talks about how more "experienced" electrical engineers can judge the amount of voltage by touching the wires to their tongue!
Be careful!
Jim