Yes... and check the tubes themselves. I've had amps that did that and replacing the offending tube cleared it up.
However, on a different note, I've always gotten into the habit of returning the volume control to minimum before turning an amp on or off - especially on. If there are any such sounds generated in the circuitry, they won't be heard - or potentially damage your speaker(s). Some amps "pop" when you turn them off...having the volume down minimizes the effect.
Bud
However, on a different note, I've always gotten into the habit of returning the volume control to minimum before turning an amp on or off - especially on. If there are any such sounds generated in the circuitry, they won't be heard - or potentially damage your speaker(s). Some amps "pop" when you turn them off...having the volume down minimizes the effect.
Bud
Delay
I think all tube amps should have a delay for the HV,only after all the tubes are warm ,the HT should be aplied ! its not good for the tubes not to do that,it shorts tubes life!
A simple way to do that is to use almost any cheap tube,and connect it in serial with a 230V relay(10 ma),connect it between the plate and ´B+ of 350V or so! When that tube is enough warm it turns the relay ON ! dont forget the cathode resistor and grid to ground!
Silvino
I think all tube amps should have a delay for the HV,only after all the tubes are warm ,the HT should be aplied ! its not good for the tubes not to do that,it shorts tubes life!
A simple way to do that is to use almost any cheap tube,and connect it in serial with a 230V relay(10 ma),connect it between the plate and ´B+ of 350V or so! When that tube is enough warm it turns the relay ON ! dont forget the cathode resistor and grid to ground!
Silvino
Curing "off" switch transient clicks that somehow get on the signal path can be difficult to eradicate: worse with high gain tube amps with wide audio b/w. Designing amps with input sensivities around 0dBu/0.775V or higher will help alot.
One solution is to make sure the input signal can be muted first and that needs to be quick. Reason: any DC offset caused by an SS opamp pre or line amp switching off is far quicker than the tube amp and must be "downed" before reaching the inputs. I've seen may opamp preamps and power amps go into oscillation on power down relying on the fast opening of a power relay in the LS circuit. Not an ideal solution.
It only takes a mere uV to create a click and there lies the problem. I try to avoid it, but never quite succeed.
........
K9Swc is right; in a mono amp with no feedback stuff, the tubes and hardware become the offenders.
........
El156....All commercial amps of the 1940,50,60 had no sensible HT delay.The TV business dictated a thermistor in the B+. It was the only limit,(not to brown outs) and only 1 component and was unreliable. It did spread to some audio amps but it was considered Too expensive. The only practical delay:- use an indirectly heated rectifier.
I believe the Walton audio block uses a directly heated 5U4;
This design avoids the B+ rocketing on near instant warmup as there is a large bleeder resistor from the raw B+ (450V) ext rectifier to chassis. I have to check the schematic. MAy be wrong. Rectifier/smoothing circuits have a nasty reputation ! In any case keep ones fingers OUT.
richy
I built a few of the 300B and 2A3 with similar 6SN7 driver. It seems like there's problem from the 6SN7 driver tube.
It is important to have the 6SN7 filament potential lifted to around 70V to avoid excessive potential difference between the cathode and filament at the 2nd stage.
Remove the 6SN7 and power it up to see if the noise is gone.
Watch if there is some ARC over occurs at the rectifier tube during power up. Use 5U4G tube - they are much more robust in this amp.
Johnny
It is important to have the 6SN7 filament potential lifted to around 70V to avoid excessive potential difference between the cathode and filament at the 2nd stage.
Remove the 6SN7 and power it up to see if the noise is gone.
Watch if there is some ARC over occurs at the rectifier tube during power up. Use 5U4G tube - they are much more robust in this amp.
Johnny
There may be 3 reasons of popping and crackings:
1. HF oscillations
2. Voltages on cathodes in respect to filaments are out of specs
3. Bad tube, with curved/loose/naked filament that touches cathode during heat up / cool down.
Startup delay would hide such problems, like sweeping garbage under the rug.
1. HF oscillations
2. Voltages on cathodes in respect to filaments are out of specs
3. Bad tube, with curved/loose/naked filament that touches cathode during heat up / cool down.
Startup delay would hide such problems, like sweeping garbage under the rug.
I think this is a complete myth. I have yet to see a single shred of evidence to the claim. Opinions are Just that... opinions. Reputable amps without HT delays can go for 10 to 20 years without noticable decay of sonic quality.
Popping and hissing is a problem that needs to be solved.
Power-on-delay of B+ however is one of these myths that continues to
live in spite of information. Same with stand-by by breaking B+, this can
even be harmful to your tubes.
Dunno… sounds like either/both crâhppy sockets or cold solder joints in the amplifier, to me. The 5–10 minute period is indicative of warm-up thermal equilibrium issues. What stabilizes after warming up? Crâhppy sockets, and cold-solder joints. And I guess if your amp has a lot of screw-type connections, them too.
I'm not discounting other people's experiences with bad tubes. They're the obvious 'first thing to try'. Swapping them out, or just channel-to-channel. Often “swapping them internally” fixes the problem … thus giving legs to the “crâhppy sockets” theory.
But I've had a lifetime of self-induced pain-and-suffering caused by seemingly nice-looking solder joints and screw-lugs that turn out to be noise makers. 35 years ago, it wouldn't have been on my list of first-guesses. That was 35 years ago.
⋅-⋅-⋅ Just saying, ⋅-⋅-⋅
⋅-=≡ GoatGuy ✓ ≡=-⋅
I'm not discounting other people's experiences with bad tubes. They're the obvious 'first thing to try'. Swapping them out, or just channel-to-channel. Often “swapping them internally” fixes the problem … thus giving legs to the “crâhppy sockets” theory.
But I've had a lifetime of self-induced pain-and-suffering caused by seemingly nice-looking solder joints and screw-lugs that turn out to be noise makers. 35 years ago, it wouldn't have been on my list of first-guesses. That was 35 years ago.
⋅-⋅-⋅ Just saying, ⋅-⋅-⋅
⋅-=≡ GoatGuy ✓ ≡=-⋅
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