I am waiting for somebody post that that's the reason they use only S/S amps.
Enjoy the benefits of a premium membership!
Upgrade Account
-
TalkBass has been independent since 1998. Add your voice.
Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
Join free Log in
Want zero display ads or expanded classifieds tools? Compare plans.
Ampeg PF50T problem after turn on
- Thread starter Rob_77
- Start date
and exactly as I was clicking on page 2 of this thread I was thinking exactly the same thing. I operated on the belief that, if anything, starting up and shutting down in standby was best.
On the other hand, though all my tube bass amps were Ampegs, I haven't owned a tube amp for several years. Maybe its something new?
Last edited:
After all the discussion, and re-reading stuff, I think I was wrong about starting, and the amp should be in standby mode when first powered - up so much for my writing/reading/interpreting skills, mea culpa.
That said, I do believe, me, that it might be beneficial to have the amp in play mode when shut down, re the discharge of caps - just turn the volume off to stop the potential speaker thump.
One more thing: I have a few tube amps, and I been doing this for a long time with no evident issues; I must be lucky!
Altho' someone, please tell me what the PF50t manual means here:
"12. STANDBY SWITCH: Use this switch to
turn the Standby Power on or off. Press
the top of the switch to disengage
the Standby circuit [ON position]. The
Standby mode allows the tubes to
warm, or remain warm, without high
voltage being applied to them, helping
to extend tube life. This switch should
be OFF when first turning the amplifier
on."
I'll not repeat myself re the VT60 manual, just mix another pop.
That said, I do believe, me, that it might be beneficial to have the amp in play mode when shut down, re the discharge of caps - just turn the volume off to stop the potential speaker thump.
One more thing: I have a few tube amps, and I been doing this for a long time with no evident issues; I must be lucky!
Altho' someone, please tell me what the PF50t manual means here:
"12. STANDBY SWITCH: Use this switch to
turn the Standby Power on or off. Press
the top of the switch to disengage
the Standby circuit [ON position]. The
Standby mode allows the tubes to
warm, or remain warm, without high
voltage being applied to them, helping
to extend tube life. This switch should
be OFF when first turning the amplifier
on."
I'll not repeat myself re the VT60 manual, just mix another pop.
Last edited:
After all the discussion, and re-reading stuff, I think I was wrong about starting, and the amp should be in standby mode when first powered - up so much for my writing/reading/interpreting skills, mea culpa.
That said, I do believe, me, that it might be beneficial to have the amp in play mode when shut down, re the discharge of caps - just turn the volume off to stop the potential speaker thump.
One more thing: I have a few tube amps, and I been doing this for a long time with no evident issues; I must be lucky!
That’s the way I do it. For amps that don’t have standby switches, you just turn off the power. It’s the same thing.
Standby switching pops can be related to arcing in the standby switch. The design can cause this, depending if you are switching AC or DC, etc. There are snubbing fixes. There are other possibilities. There always are.
A pop after the amp is running in playing mode can be due to a tube or a tube socket contact issue. A simple test for the tube is to swap in a known good one, one at a time and see if it goes away.
A pop after the amp is running in playing mode can be due to a tube or a tube socket contact issue. A simple test for the tube is to swap in a known good one, one at a time and see if it goes away.
IMHO they both describe the correct procedure, but they make comprehension about as difficult as possible. The directions make sense to me because I know what is going on under the hood, and don't get confused by their awkward language (double talk).
Hopefully this is easier to understand.
Turn On Sequence
Power Switch_____________Standby Switch
Off_____________________Standby (the switch is off)
On_____________________Standby (no change)
after the amp has warmed sufficiently
On_____________________Operate (the switch is on)
Turn Off Sequence
Power Switch____________Standby Switch
On____________________Operate (the switch is on)
On____________________Standby (the switch is off)
Off____________________Standby (no change)
So here is the Sweetwater version of the argument. They blamed Leo.
Please take it all with a grain of salt. I am an electronics tech of 50+ years, but a retired broadcaster, not an amp tech. This is me simply regurgitating the words of an "Internet guru".
The Great Standby Switch Myth - SweetCare
Yes, tube broadcast transmitters typically operate at much higher voltages than tube instrument amps. Thousands of Volts rather than hundreds. The concern at those higher voltages was a phenomenon called Cathode Stripping.
Additional and somewhat balanced forum discussion here. It mentions Cathode Stripping.
(Regurgitated Internet caution applies)
What the ???? Standby Switch is bad for tubes????
Likewise, SW also posted about Cathode Stripping.
(Regurgitated Internet caution applies)
Cathode Stripping - inSync
Being a transmitter tech I knew that tube transmitters operated at these higher voltages. They not only had separate Filament and High Voltage (AKA Plate) on/off switches, but also included a timing circuit to prevent Plates ON, before being being fully warmed up.
As a result, I too included (unnecessarily IMO, now) a standby switch when I built from scratch a Ham Radio transmitter using a single 6L6. (It's a Ham thing... like A Jedi Knight building his own lightsaber.)
So take all this FWIW, which may just be my attempt push my fearless prediction for 2023.
Please take it all with a grain of salt. I am an electronics tech of 50+ years, but a retired broadcaster, not an amp tech. This is me simply regurgitating the words of an "Internet guru".
The Great Standby Switch Myth - SweetCare
Yes, tube broadcast transmitters typically operate at much higher voltages than tube instrument amps. Thousands of Volts rather than hundreds. The concern at those higher voltages was a phenomenon called Cathode Stripping.
Additional and somewhat balanced forum discussion here. It mentions Cathode Stripping.
(Regurgitated Internet caution applies)
What the ???? Standby Switch is bad for tubes????
Likewise, SW also posted about Cathode Stripping.
(Regurgitated Internet caution applies)
Cathode Stripping - inSync
Being a transmitter tech I knew that tube transmitters operated at these higher voltages. They not only had separate Filament and High Voltage (AKA Plate) on/off switches, but also included a timing circuit to prevent Plates ON, before being being fully warmed up.
As a result, I too included (unnecessarily IMO, now) a standby switch when I built from scratch a Ham Radio transmitter using a single 6L6. (It's a Ham thing... like A Jedi Knight building his own lightsaber.)
So take all this FWIW, which may just be my attempt push my fearless prediction for 2023.
- Feb 12, 2006
- 61,031
- 5
- 220,922
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
There's a lot more to it that needs to be taken in context, some of which is what happens to the bias at turn-on and what happens to the screen supply at turn-on.
What I suggested earlier is the most generally safe and accepted method, though there are some exceptions that are also safe. The problem is knowing which ones they are. For example, the bias issue does not happen in a cathode biased amp.
What I suggested earlier is the most generally safe and accepted method, though there are some exceptions that are also safe. The problem is knowing which ones they are. For example, the bias issue does not happen in a cathode biased amp.
I like the Tung-Sol reissue. This one. BTW, the amp requires a matched pair of 6L6GC’s. A 6L6 is not the same.
Invalid Link Removed
- Feb 12, 2006
- 61,031
- 5
- 220,922
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
Could certainly be. I have no idea how old the tubes are at this point. I got the thing back in 2019, and it was used then.
Seems more likely to happen if I suddenly start playing louder, if that indicates anything.
Makes me think I’m right about a tube failure.
The most likely culprit is always V1 preamp, but not always. And tubes don’t need to be changed regularly. I’ve only changed one tube in my 50t and I’ve had it since they came out.
