Hello Everyone,
I started building Dave Hunter's two stroke amp. The circuit appears to be a lot like a Tweed Champ with a 'boost' circuit that works by changing the bias of the pre-amp tube.
Anyways, I am having an issue, which I think is isolated to the pre-amp / tone stack though I wanted to ask you for your opinion on what you thought.
Issue Summary
I do not get any sound from the input jack when I plug a guitar in. I also noticed the amp's hum / hiss does not increase as I turn the volume up. I do hear some general hum, which I believe is coming from the power transformer.
If I insert an audio probe on the 68k resistor on the input jack (with my iphones headphone jack as the source turned the hole way up) I can hear a faint sound. If I connect the audio probe to the pre-amp tube at pin 2 bybassing the 68k resistor I get a slightly louder sound. If i connect the audio probe to pin 7, which is connected to Lug 2 of the volume pot, I also get a sound.
I also noticed if I connect the audio prob to lug 3 or 2 of the volume pot, I get sound. Lug 1 (furthermost left, looking down with the lugs facing towards the open back of the chassis) is ground. The sound I do hear, is not loud, nor does it change when I turn the volume knob.
It also appears that the tone knobs does not work when inserting signal with the test prob.
The filter cap voltages seem good. The rectifier voltages seem good.
I was wondering if you anyone has any thoughts on what might be the cause of this issue.
Layout
http://www.tubeampnetwork.com/wp-con...isedLayout.jpg
Schematic
http://www.tubeampnetwork.com/wp-con..._Schematic.jpg
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I started building Dave Hunter's two stroke amp. The circuit appears to be a lot like a Tweed Champ with a 'boost' circuit that works by changing the bias of the pre-amp tube.
Anyways, I am having an issue, which I think is isolated to the pre-amp / tone stack though I wanted to ask you for your opinion on what you thought.
Issue Summary
I do not get any sound from the input jack when I plug a guitar in. I also noticed the amp's hum / hiss does not increase as I turn the volume up. I do hear some general hum, which I believe is coming from the power transformer.
If I insert an audio probe on the 68k resistor on the input jack (with my iphones headphone jack as the source turned the hole way up) I can hear a faint sound. If I connect the audio probe to the pre-amp tube at pin 2 bybassing the 68k resistor I get a slightly louder sound. If i connect the audio probe to pin 7, which is connected to Lug 2 of the volume pot, I also get a sound.
I also noticed if I connect the audio prob to lug 3 or 2 of the volume pot, I get sound. Lug 1 (furthermost left, looking down with the lugs facing towards the open back of the chassis) is ground. The sound I do hear, is not loud, nor does it change when I turn the volume knob.
It also appears that the tone knobs does not work when inserting signal with the test prob.
The filter cap voltages seem good. The rectifier voltages seem good.
I was wondering if you anyone has any thoughts on what might be the cause of this issue.
Layout
http://www.tubeampnetwork.com/wp-con...isedLayout.jpg
Schematic
http://www.tubeampnetwork.com/wp-con..._Schematic.jpg
--
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