theoman
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Posts posted by theoman
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I blew out my diaphragms on my horns in my Altecs and replaced them with the ones from china. is there much difference in the US models?
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Im in Houston not much service out here
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he knows I'm using 2A3s.
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From Craig at Eddie Current (moth)You need to measure the bias resistor to see what the bias voltage should read. The 45 tubes need about 36mA, so if the resistor is 1 ohm the meter should read 36mV. Make sure you have the correct tubes, I have not seen a 45 tube that looks like that.I don't understand what he's talking about!
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why am I only able to load one picture only?
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Bingo!
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2
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1 hour ago, mike stehr said:
Okay, I read through the audiokarma thread.
The one guy asked to pull the rectifier tube, (GZ34) to see if the hum/buzz went away. I recall you mentioned that you did that and the hum went away.
He mentioned that if the hum went away, that it's possibly a wiring/grounding/layout issue. Judging by the way the amplifier is laid out and wired, it's a bit of a mess and wouldn't doubt that the wiring/grounding could be the problem.
I can't recall if the Moth SET amplifiers of the day had kits, like Welborne labs. It appears to be wired like a kit, or other owners may have added different parts. (The Jupiter coupling caps were not around when this amp was new I'm guessing.)
The output tubes, (2A3) are indirectly heated with DC, using some sort of voltage regulation. I have no idea if the pots are for hum nulling or not. Did you happen to see if those pots changed in the millivolt range when your turned them?
Sometimes triode output tubes get a bit noisy getting to the end of their life as the emission lowers, that's why I asked if you had a way to test them. Even the driver tubes and rectifier could be tested. A guy can test them in circuit by confirming proper voltages/current, but one will have to probe around in a powered amplifier.
The amplifier is a bit older, and there may be a dried up cap or two, but I don't really think that's the issue...maybe part of it...
Without a schematic or some sort of manual be it assembly or operating, it's a bit of a chore to figure out the circuit from pictures of underside wiring, how it works, etc...
There a forum member named Eric Mandaville (I hope I spelled his last name correct) who I'm pretty sure has a Moth audio amplifier...maybe it's pre-amp. He'd be the guy with most knowledge about Moth audio around here I would think.
Maybe find the schematic or a manual and befriend someone locally who happens to be into tube audio, either a tech or enthusiast who can look over the amplifier.
You can learn quite a bit that way.
I will get the all tubes checked out Friday. Do you think the Amp is worth saving? if not I still can sent it back to the estate. I paid 1,100 for it.
here's the deceased owner thread on the amp
http://audiokarma.org/forums/index.php?threads/moth-s45-arrives.1079/
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Here's from Craig at Eddie Current:
All Moth amps had manuals with schematics. If you got the amp it should have been sent in a wooden crate with the manual. That amp is 17 years old and it is likely the electrolytic caps are dried out which would account for the buzz. I don’t have any documentation on the Moth amps, and don’t work on them.
You need to measure the bias resistor to see what the bias voltage should read. The 45 tubes need about 36mA, so if the resistor is 1 ohm the meter should read 36mV. Make sure you have the correct tubes, I have not seen a 45 tube that looks like that. -
2 hours ago, theoman said:
I can't find a schematic.
What does grounding a RCA do?
Here's a link to all the picture's:
http://audiokarma.org/forums/index.php?threads/moth-audio-45.791782/
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9 hours ago, mikebse2a3 said:
Could be ground or capacitor or design issues.
If you can find a schematic and/or comfortable working with amplifiers you can take pictures of it's internal construction then we might can help more.
CAUTION: Be careful it's possible if not designed with power supply bleeder resistors to have 250v to 400v stored in the pwr supply capacitors.
I can't find a schematic.
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9 hours ago, mike stehr said:
Is the Moth 45 an amplifier for 45 type output tubes, or is a convertible amp which can also use 2A3 or 300B?
It also can take 45B's
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7 minutes ago, mikebse2a3 said:
this HTML class. Value is http://www.6moons.co
the link did not work.
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no buzz when the when I pull the rectifier tube outs it have to be a ground
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2 minutes ago, mikebse2a3 said:
Some things you might try.
If it has a Hum/Buzz control try adjusting it.
If you remove the input cables to the amplifier do you still hear the buzz..? It's actually best to use RCA shorting plugs on the input for this test if you have any.
Is all the equipment plugged into the same AC outlet ..?
Any AC plugs that are non-polarzed (ie: 2 prongs of equal size) can be reversed in the ac receptacle to see if that reduces the buzz.
Another thing to check for would be if you are using any light dimmers try turning them totally off and see if the buzz goes away.
miketn
buzz at all volumes with nothing connected. heres the buzz
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4 minutes ago, mike stehr said:
What brand are those output tubes? Do you have a way to test them?
I'm taking a guess that it sounds like 120Hz hum, from what could be the filaments...maybe power supply related?
Another guess that the amplifier doesn't have bias adjustment. But it should or might have hum adjustment pots.
If it does, did you try adjusting for least hum?
Nice amp. Those are some good sized output transformers.
here's the tubes. that would be great if it is. what brand is this? is it cheap?
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theres a buzz at all volumes even changed the power cord
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the amp sounds great but it has a hum and the guys on AK sent me over here. I don't know the how or what the bias should be?
I can't find and info on them. I tried Craig but no reply.
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Does anyone have any info on this Amp? I bought it from the estate of a orignal AK member.
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here's the only ID on the speakers in the cabinets.
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All cleaned up.
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Here's the one in the cabinets. the guy really carved the boxes getting them in.
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the newer subs are in the LaScala's and were purchased in 2003. heres the marking on the box.
i'm wondering why the guy replaced them. they sound great. now that I look at them they are both K43's the newer one are EP's. One side of box says K 43 E and other says K 43 E.
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Well, I picked up a pair of La Scala's today still in the box with extra woofers. i can't figure out the difference between the subs it came with. k-43 88-44 are in the boxes and K-43-EPs are in the cabinets.what are K-43-EPs. bear with me I'm a newbie.
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sorry for the newbie question. I am a long time Audiokarma guy retting into Klipsch's. why are the one's made in the 80's going for 1/2 the price of 70's. is it like a fine wine? I was looking at the la scalas with my mcintosh tube amps but I maybe able to get into a pair of 80's Klipschorn's
Moth Audio 45
in Talkin' Tubes
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has anyone compared the ones made in china and the states? not saying they are made here.