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Topic: Ghost notes from the amp |
Tim Whitlock
From:
Colorado, USA
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Posted 8 Nov 2012 8:13 am |
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I'm hearing some ghost notes coming out of my Standel amp, most noticeably when I play a third or a fifth up around the 12th - 15th fret. I hear the two notes I am picking but also a third note, much lower and not as loud. As I slide down the neck the ghost note gets lower and lower until it drops below the human ear's audible range.
At first I thought it might be cone cry from the speakers, but I hooked the Standel up to the speakers in my Twin Reverb and the effect was still there. I don't get the effect when I play through my Twin, so I conclude that the effect is somewhere in the Standel circuit.
Do any of the electronics guys here have any thoughts on what might be generating these ghost notes? Thanks! |
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Tim Marcus
From:
San Francisco, CA
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Posted 8 Nov 2012 8:36 am
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when is the last time you replaced the capacitors in the power supply?
That is often the cause of ghosting
_________________
Milkmansound.com |
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Tim Whitlock
From:
Colorado, USA
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Posted 8 Nov 2012 9:33 am
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Thanks Tim. My tech just rebuilt the power supply as part of an overall tune up. I don't know what all it included. I will ask him about the ghosting, but from what I read on the www it's a common phenomenon related to the power supply filters. According to the discussion more filtering can reduce the effect but may also have a negative effect on the sound of the amp?
It's pretty subtle but annoying and I'm afraid it might be audible if I try to record with this amp. Not so noticeable with the band. Any other thoughts? |
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Daniel Policarpo
From:
Kansas City
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Posted 9 Nov 2012 3:43 am
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| Which Standel model do you have? |
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Eric Philippsen
From:
Central Florida USA
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Posted 9 Nov 2012 4:43 am
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It's your power supply filter caps. It's one or more of three things.
- The caps are original and worn out.
- the caps your tech put in are bad or of poor, cheap quality.
- The cap values need to be increased.
Is there a tonal change from increasing filter cap values? Yes, your ghost notes go away. |
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Tim Whitlock
From:
Colorado, USA
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Posted 9 Nov 2012 7:57 am
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| Daniel Policarpo wrote: |
| Which Standel model do you have? |
1969 Standel Artist AG24 that I rebuilt and customized. It's all solid state 2x12 with 4 main transistors. This is now my #1 amp and the Twin is relegated to backup status. I mostly notice the ghosting when practicing at home. If it turns out to be an issue with gigging or recording I will talk to my tech about increasing the filtering. Appreciate the responses!
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Stephen Cowell
From:
Round Rock, Texas, USA
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Posted 9 Nov 2012 9:24 am
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Some of these old SS amps have a bias control... normally this is set to make sure there's no DC on the speaker output. Not sure if your amp is direct-coupled or not... talk to your tech. If it does have an OT, unbalanced DC on the primary can saturate the OT and cause distortion... or improper bias can cause crossover distortion.
_________________
Too much junk to list... always getting more. |
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Bob Hoffnar
From:
Austin, Tx
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Posted 9 Nov 2012 12:04 pm
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It might be that you are overloading the input. That can cause the appearance of difference tones on those intervals. I would try buffering the input before surgery.
_________________
Bob |
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Tim Whitlock
From:
Colorado, USA
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Posted 9 Nov 2012 3:53 pm
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| Thanks for the suggestion Bob. My Fender 1000 pickup measures around 8 ohms, so I think we can rule out input overload. I did flip the buffer switch and it lowered the overall signal but the ghosting was still there in roughly the same proportion to the signal. |
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Daniel Policarpo
From:
Kansas City
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Posted 9 Nov 2012 6:33 pm
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While these things are a bit irritating when they come up, at least we can still hear them when they do.
That is a beautiful looking Standel, Tim! One day I envision one sitting in my den. |
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Roual Ranes
From:
Atlanta, Texas, USA
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Posted 10 Nov 2012 9:33 am
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I don'thave a Standel butI really thank you for posting this info.........I plan touse the term "Ghost Note" for an excuse from now on.  |
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Donny Hinson
From:
Glen Burnie, Md. U.S.A.
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Posted 12 Nov 2012 2:52 pm
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| Tim Whitlock wrote: |
| Thanks for the suggestion Bob. My Fender 1000 pickup measures around 8 ohms... |
Your Fender 1000 pickup should be measuring 8,000 ohms (8k), and usually that's not hot enough to cause overdriving problems. |
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Clete Ritta
From:
San Antonio, Texas
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Posted 12 Nov 2012 7:22 pm
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Did the amp sound fine before? Does the sound occur at very low volumes on the amp too? It might be caused by distortion at louder levels? I've heard those ghost notes thru a tube amp (Super Twin) before, and I wasnt quite sure what caused the overtone. Do faulty filter caps cause the ghost note effect in tube amps too?
Clete |
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Kelvin Monaghan
From:
Victoria, Australia
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Posted 13 Nov 2012 2:13 am
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Power supply filtering or possibly ground lead dress.Vintage Vox AC 30s are notorious for it.
Cheers |
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Tim Whitlock
From:
Colorado, USA
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Posted 13 Nov 2012 6:29 am
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| Donny Hinson wrote: |
| Tim Whitlock wrote: |
| Thanks for the suggestion Bob. My Fender 1000 pickup measures around 8 ohms... |
Your Fender 1000 pickup should be measuring 8,000 ohms (8k), and usually that's not hot enough to cause overdriving problems. |
Oops forgot the "k". Thanks Donny! |
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