Warming up KT-88's

Let's talk guitar amplfiers

Moderator: jingle_jangle

Re: Warming up KT-88's

Postby (soundmasterg) » Sat Apr 23, 2016 2:20 am

Hi Jeff,

Your question was already essentially answered with the link to the valvewizard site. The thing you have to remember is that there is a LOT of misinformation out there about tube amps and some of it even comes from the companies you buy your gear from! I will say this.....receiving tubes are the type we use for musical instrument amps. Transmitter tubes are types that were/are used for ham radios and things of that nature. It says right in the RCA tube manual that receiving tubes are not susceptible to cathode stripping, which is the main reason people give for needing to use a standby switch. The reason for this is that receiving tubes can't work at a high enough voltage where cathode stripping might occur. Transmitting tubes can operate at those voltages however, so they should be using a standby of some sort. It doesn't matter if you have a solid state rectifier, or a tube rectifier as the tubes in our amps are not bothered at all with cathode stripping or being hit with voltage before they are warmed up. That said, a standby switch is useful as a mute when on stage, but you should never leave your amp in standby for hours at a time without playing as cathode poisoning can occur, which essentially makes the tube exhaust its ability to emit electrons internally, or in other words it wears the tube out rather quickly if the amp is left in standby for hours at a time. The standby switch is a useful feature to have for the repair person, which is probably why Leo Fender incorporated it originally, but it is really not needed, no matter what Mesa Boogie says. They are famous for saying a lot of things that have no basis in reality, trust me. :mrgreen: The sounds your amp made when you shut it off with the standby left in play mode were something else rather than something connected to the standby feature, and is likely not a concern. All tube amps will sound different as they have been on awhile versus initially turning them on. This is normal and is caused by the tubes being fully warmed up, and the parts inside the amp changing temperature also from the heat of the tubes and transformers. The tubes in the amp will warm up quicker if you have the standby in play mode when you turn the power on but it doesn't really matter much either way. Just ignore anything Mesa Boogie said about a warm up period....it isn't necessary.

The only amps using a tube rectifier that have a soft start are the ones using the GZ34/5AR4 tube as it delays hitting the power tubes with the B+ by about 20 seconds. As I said though, it doesn't really matter. The bigger concern is what happens to the caps in the power supply....when you turn the amp on and let it sit there in standby mode, depending on the design of the amp, the first filter caps in the power supply can be over voltage, which isn't good for them and eventually will make them fail. If this happens or not depends on the design of the amp though and I can't tell you yea or nay without looking at the schematic, the caps in question, and the voltages involved. There are amps that never used a standby switch and still have original tubes in them like my real 1956 Fender 5E3 tweed deluxe. This is an amp that uses a 5Y3 rectifier tube which is a directly heated type and which hits the tubes with voltage immediately once the amp is turned on. When you talk about an Ampeg SVT, or perhaps your boogie, they often run voltages up around 600-700V and this is getting close to needing a standby switch, but they are still ok without one. If you have it, then use it when you are pausing from playing music with the amp and you need a mute function if you want, or use the mute switch, but don't stress the use of the standby switch. Use it or not, it won't matter, as long as you don't leave it running in standby for hours at a time.

There was tons of equipment made back in the day when tubes WERE electronics and there was nothing else that did not have standby switches. Tube TV's had super high voltages in them, sometimes above 40,000 volts, and no standby switches to be found, because they were using receiving tubes except for the CRT tube, which didn't need a standby. Tube stereos don't and didn't have standby switches....I have an RCA console tube stereo here from 1964...no standby switch to be found....still using the original tubes. Tubes and tube amps by nature are simple and robust and can withstand a lot, even misinformation. :mrgreen:

Enjoy your amp!

Greg
User avatar
(soundmasterg)
RRF Consultant
 
Posts: 1906
Joined: Tue Oct 01, 2002 1:06 pm
Location: Cornelius, Oregon, USA

Re: Warming up KT-88's

Postby (jps) » Sat Apr 23, 2016 2:13 pm

soundmasterg wrote:Hi Jeff,

Your question was already essentially answered with the link to the valvewizard site. The thing you have to remember is that there is a LOT of misinformation out there about tube amps and some of it even comes from the companies you buy your gear from! I will say this.....receiving tubes are the type we use for musical instrument amps. Transmitter tubes are types that were/are used for ham radios and things of that nature. It says right in the RCA tube manual that receiving tubes are not susceptible to cathode stripping, which is the main reason people give for needing to use a standby switch. The reason for this is that receiving tubes can't work at a high enough voltage where cathode stripping might occur. Transmitting tubes can operate at those voltages however, so they should be using a standby of some sort. It doesn't matter if you have a solid state rectifier, or a tube rectifier as the tubes in our amps are not bothered at all with cathode stripping or being hit with voltage before they are warmed up. That said, a standby switch is useful as a mute when on stage, but you should never leave your amp in standby for hours at a time without playing as cathode poisoning can occur, which essentially makes the tube exhaust its ability to emit electrons internally, or in other words it wears the tube out rather quickly if the amp is left in standby for hours at a time. The standby switch is a useful feature to have for the repair person, which is probably why Leo Fender incorporated it originally, but it is really not needed, no matter what Mesa Boogie says. They are famous for saying a lot of things that have no basis in reality, trust me. :mrgreen: The sounds your amp made when you shut it off with the standby left in play mode were something else rather than something connected to the standby feature, and is likely not a concern. All tube amps will sound different as they have been on awhile versus initially turning them on. This is normal and is caused by the tubes being fully warmed up, and the parts inside the amp changing temperature also from the heat of the tubes and transformers. The tubes in the amp will warm up quicker if you have the standby in play mode when you turn the power on but it doesn't really matter much either way. Just ignore anything Mesa Boogie said about a warm up period....it isn't necessary.

The only amps using a tube rectifier that have a soft start are the ones using the GZ34/5AR4 tube as it delays hitting the power tubes with the B+ by about 20 seconds. As I said though, it doesn't really matter. The bigger concern is what happens to the caps in the power supply....when you turn the amp on and let it sit there in standby mode, depending on the design of the amp, the first filter caps in the power supply can be over voltage, which isn't good for them and eventually will make them fail. If this happens or not depends on the design of the amp though and I can't tell you yea or nay without looking at the schematic, the caps in question, and the voltages involved. There are amps that never used a standby switch and still have original tubes in them like my real 1956 Fender 5E3 tweed deluxe. This is an amp that uses a 5Y3 rectifier tube which is a directly heated type and which hits the tubes with voltage immediately once the amp is turned on. When you talk about an Ampeg SVT, or perhaps your boogie, they often run voltages up around 600-700V and this is getting close to needing a standby switch, but they are still ok without one. If you have it, then use it when you are pausing from playing music with the amp and you need a mute function if you want, or use the mute switch, but don't stress the use of the standby switch. Use it or not, it won't matter, as long as you don't leave it running in standby for hours at a time.

There was tons of equipment made back in the day when tubes WERE electronics and there was nothing else that did not have standby switches. Tube TV's had super high voltages in them, sometimes above 40,000 volts, and no standby switches to be found, because they were using receiving tubes except for the CRT tube, which didn't need a standby. Tube stereos don't and didn't have standby switches....I have an RCA console tube stereo here from 1964...no standby switch to be found....still using the original tubes. Tubes and tube amps by nature are simple and robust and can withstand a lot, even misinformation. :mrgreen:

Enjoy your amp!

Greg
Thanks for amplifying my simple posts, Greg. :mrgreen:
User avatar
(jps)
RRF Consultant
 
Posts: 36421
Joined: Wed Feb 12, 2003 6:00 am
Location: Not of this Earth

Re: Warming up KT-88's

Postby (rickaddict) » Tue Apr 26, 2016 9:51 pm

Thanks Greg (and Jeff).

Interesting and informative.

...and now I'm gonna go play through my B-15R!

8)
(rickaddict)
Senior Member
 
Posts: 6163
Joined: Mon Mar 29, 2004 7:46 am
Location: Chicago, IL, U.S.A.

Re: Warming up KT-88's

Postby (jps) » Tue Apr 26, 2016 10:06 pm

rickaddict wrote:Thanks Greg (and Jeff).

Interesting and informative.

...and now I'm gonna go play through my B-15R!

8)

Fine, you just do that! I am going to play through my Swart! :twisted:
User avatar
(jps)
RRF Consultant
 
Posts: 36421
Joined: Wed Feb 12, 2003 6:00 am
Location: Not of this Earth

Re: Warming up KT-88's

Postby (soundmasterg) » Mon May 02, 2016 2:10 am

You're welcome guys.

While you're plaing, I'll be playing through my Sunn 2000S. :mrgreen:

Greg
User avatar
(soundmasterg)
RRF Consultant
 
Posts: 1906
Joined: Tue Oct 01, 2002 1:06 pm
Location: Cornelius, Oregon, USA

Re: Warming up KT-88's

Postby (jps) » Mon May 02, 2016 5:07 pm

The first bass amp I ever used (in the very early '70s was a 2000S with matching cab.
User avatar
(jps)
RRF Consultant
 
Posts: 36421
Joined: Wed Feb 12, 2003 6:00 am
Location: Not of this Earth

Re: Warming up KT-88's

Postby (soundmasterg) » Wed Jun 01, 2016 2:14 am

jps wrote:The first bass amp I ever used (in the very early '70s was a 2000S with matching cab.


Nice! What did you think of it?

I used to have an all original early 1967 200S and cabinet but sold it to get an SVT head, and I wanted the Sunn sound again. So I picked up a Sonic 1 head that needed lots of work, but it was a later one with the Schumacher transformers instead of the Dynaco ones (higher voltage and less sweet sound on the later ones but more power), so after I fixed it, I sold it. I also happened to luck out on a great deal for a very early 2000S head (free) and then later a loaded cabinet with original JBL's ($300) so I was back in the Sunn game again. I still need to rebuild it but it mostly works ok. I sold the SVT head and a couple cabinets since the 2000S can get enough volume these days with PA's, and I think it sounds better too, but I also needed money for school. I can get my Ampeg sound with a 1963 B15N that I am restoring. I'd like to pick up an early 200S head someday but it isn't a priority since I am a guitar player first. :)

Greg
User avatar
(soundmasterg)
RRF Consultant
 
Posts: 1906
Joined: Tue Oct 01, 2002 1:06 pm
Location: Cornelius, Oregon, USA

Re: Warming up KT-88's

Postby (jps) » Wed Jun 01, 2016 6:15 pm

Honestly, I don't remember as that was 45 years ago! The friend who had it also had a Marshall 50 watt head (small case, so probably a model 1987) with 4-12 cabinet that I used to borrow for extended periods of time; the Sunn was just too big and heavy for me move around by myself, I could manage the Marshall cabinet fine, though.
User avatar
(jps)
RRF Consultant
 
Posts: 36421
Joined: Wed Feb 12, 2003 6:00 am
Location: Not of this Earth

Previous

Return to Greg's Amplifier and Tube Tech Forum: by Greg Simon

Who is online

Users browsing this forum: No registered users and 2 guests