I have recently completed a Simple SE, and am very happy with it - I think I may have a problem though.
Intermittently one channel - always the same channel, will get quite distorted, and even almost completely so silent. This has happened every time the amp has run for more an hour or so.
Just now it was doing it (one channel extremely distorted), I turned the power switch off and back on, and all was fine (was off for barely enough time for the heaters to go out), and still is now......
Source is an iPod (headphone socket) as I haven't done a volume pot yet - I was hoping it was the iPod with a problem, but this latest occurrence makes me wonder..... all speaker connections are tight.
am using EL34, B+ 440V (Hammond 374BX), Rk 770ohm
any thoughts?????
TIA, Lee
Intermittently one channel - always the same channel, will get quite distorted, and even almost completely so silent. This has happened every time the amp has run for more an hour or so.
Just now it was doing it (one channel extremely distorted), I turned the power switch off and back on, and all was fine (was off for barely enough time for the heaters to go out), and still is now......
Source is an iPod (headphone socket) as I haven't done a volume pot yet - I was hoping it was the iPod with a problem, but this latest occurrence makes me wonder..... all speaker connections are tight.
am using EL34, B+ 440V (Hammond 374BX), Rk 770ohm
any thoughts?????
TIA, Lee
I had the same problem and it turned out to be my ipod dying in one channel however the following possibilities should be considered:
1/bad tube
2/tighten up any conncectors/wires that are loose
3/tidy up internal wiring as best as possible
3/test the coupling caps, one might be bad
however, I find the problem is often the most obvious (bad tube is always 1 suspect)
1/bad tube
2/tighten up any conncectors/wires that are loose
3/tidy up internal wiring as best as possible
3/test the coupling caps, one might be bad
however, I find the problem is often the most obvious (bad tube is always 1 suspect)
Likely causes are:
Bad tube:
Swap the EL34's and see if the problem migrates to the other channel. Try another 12AT7.
Loose socket pin:
After the amp dies, CAREFULLY lightly wiggle each tube. If moving a tube fixes it, check the soldering where the socket meets the board, if OK, GENTLY squeeze each pin in the socket with a pair of tweezers so it grips the tube pins tighter. Some JJ EL34's had undersized pins.
intermittent solder connection:
Go over the board carefully.
Screw not tight on wiring terminal:
They have a way of losening in the first month after construction.
Bad tube:
Swap the EL34's and see if the problem migrates to the other channel. Try another 12AT7.
Loose socket pin:
After the amp dies, CAREFULLY lightly wiggle each tube. If moving a tube fixes it, check the soldering where the socket meets the board, if OK, GENTLY squeeze each pin in the socket with a pair of tweezers so it grips the tube pins tighter. Some JJ EL34's had undersized pins.
intermittent solder connection:
Go over the board carefully.
Screw not tight on wiring terminal:
They have a way of losening in the first month after construction.
I think its the iPod, and I think it occurs only when its running from its battery..... I swapped the input leads this morning, and it has been playing all day almost, without a problem , but the iPod has been on its AC-adaptor.
Could the Simple SE be too much of a load on the 'pod's headphone jack? That the battery won't supply enough juice at times??? It is 3yr old, battery might be getting weak.....
The amp really does sound sweet though......
Could the Simple SE be too much of a load on the 'pod's headphone jack? That the battery won't supply enough juice at times??? It is 3yr old, battery might be getting weak.....
The amp really does sound sweet though......
OK now I'm annoyed!
1. swapped input channels over - problem recurred in the same speaker, this time with a different ipod
2. checked board connections and solder joints - all look OK, one of the input connections seemed loose, so tightened it up (the nut around the RCA socket base) - problem recurred in same speaker
3. wiggled EL34's - no change
4. swapped EL34's - seemed fixed immediately last night, played for hours without a hitch
5. today - same problem, starts cold with one speaker quiet.....
6. changed ipod back to original one - playing fine!
What are the chances this is a dud 12AT7?? This is frustratingly intermittent! I really need to wire a volume knob and use a line level input.... still think it's the damn ipod somehow!!
1. swapped input channels over - problem recurred in the same speaker, this time with a different ipod
2. checked board connections and solder joints - all look OK, one of the input connections seemed loose, so tightened it up (the nut around the RCA socket base) - problem recurred in same speaker
3. wiggled EL34's - no change
4. swapped EL34's - seemed fixed immediately last night, played for hours without a hitch
5. today - same problem, starts cold with one speaker quiet.....
6. changed ipod back to original one - playing fine!
What are the chances this is a dud 12AT7?? This is frustratingly intermittent! I really need to wire a volume knob and use a line level input.... still think it's the damn ipod somehow!!
intermittent bugs are the hardest to find.
12at7's are cheap aren't they? Get an extra.
For something like this I'd start by removing one thing at a time until the problem goes away (for good).
For example - use a source other than your ipods. Change the cable. Change the input tube. change the speaker cables, make sure it's not your speaker that has the issue. Take an ohm meter and check the wiring from the input jacks to the pcb (and wiggle the wires while you check)
Eventually you'll find it.
12at7's are cheap aren't they? Get an extra.
For something like this I'd start by removing one thing at a time until the problem goes away (for good).
For example - use a source other than your ipods. Change the cable. Change the input tube. change the speaker cables, make sure it's not your speaker that has the issue. Take an ohm meter and check the wiring from the input jacks to the pcb (and wiggle the wires while you check)
Eventually you'll find it.
When you swapped tubes, did the issue follow the tube? If not, I would reflow the solder joints on that socket. If that doesn't help and the leads to the OPTs are long enough, try swapping OPTs.
More steps:
Put a pair of volt meters across the cathode resistors and note the voltage after warmup. Now just forget about them until the issue happens and observe the voltages then. Repeat (or use a 3rd and 4th meter) across the 330 ohm plate load resistors. If one of the voltages falls when the issue happens, then you know where to start looking.
More steps:
Put a pair of volt meters across the cathode resistors and note the voltage after warmup. Now just forget about them until the issue happens and observe the voltages then. Repeat (or use a 3rd and 4th meter) across the 330 ohm plate load resistors. If one of the voltages falls when the issue happens, then you know where to start looking.
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