Thunderbird Club

[JJR58]

@hillerup is the man, he's less than 30 pages to go. God bless him.

 

[Stevis]

The biasing would be causing excessive breakup (and burning through your output valves).

This tube bias stuff ties my tiny cat brain in knots. As I understand it, smaller tube amps are often Cathode bias, where you can put in new tubes and rock on. I am less familiar with the non-adjustable fixed bias variety, which is also no muss/no fuss.

All of my tube amps are smallish guitar amps (5w to 15w). I don't own a tube bass head/combo. But it seems like the ones I have looked at suggest taking it to a tech to adjust bias, when putting a new set of tubes in them. Is this because you are typically talking about something that is more than 50w (i.e., "More power, Scotty!")?

 

[willsellout]

Removed the tone cap from the Epi. Didn't notice a huge difference. I'm a bit bored with the Tbird at this point so I think it's a good time to take it apart and put in some solid high quality components. Maybe switch the pots to 500K to see if that adds a little something to the mix.

 

[JJR58]

This tube bias stuff ties my tiny cat brain in knots. As I understand it, smaller tube amps are often Cathode bias, where you can put in new tubes and rock on. I am less familiar with the non-adjustable fixed bias variety, which is also no muss/no fuss.

All of my tube amps are smallish guitar amps (5w to 15w). I don't own a tube bass head/combo. But it seems like the ones I have looked at suggest taking it to a tech to adjust bias, when putting a new set of tubes in them. Is this because you are typically talking about something that is more than 50w (i.e., "More power, Scotty!")?

Vince?, Kat?.............

 

[JJR58]

Removed the tone cap from the Epi. Didn't notice a huge difference. I'm a bit bored with the Tbird at this point so I think it's a good time to take it apart and put in some solid high quality components. Maybe switch the pots to 500K to see if that adds a little something to the mix.

500K pots is what should be in there. And a Switchcraft output jack.

 

[Dr_Feelgoood212]

Vince?, Kat?.............

Kat?

 

[willsellout]

500K pots is what should be in there. And a Switchcraft output jack.

I didn't take a look to see what pots are in there but I know they are cheap crap. Now is a good time to shield it and add in some quality stuff.

 

[JJR58]

I didn't take a look to see what pots are in there but I know they are cheap crap. Now is a good time to shield it and add in some quality stuff.

Put in good quality components, it'll help big time.

 

[Stevis]

Kat?

Bueller? Bueller?

 

[kat888]

This tube bias stuff ties my tiny cat brain in knots. As I understand it, smaller tube amps are often Cathode bias, where you can put in new tubes and rock on. I am less familiar with the non-adjustable fixed bias variety, which is also no muss/no fuss.

All of my tube amps are smallish guitar amps (5w to 15w). I don't own a tube bass head/combo. But it seems like the ones I have looked at suggest taking it to a tech to adjust bias, when putting a new set of tubes in them. Is this because you are typically talking about something that is more than 50w (i.e., "More power, Scotty!")?

It will be the circuit design, not the rated output power. My YBA200 had an autobiasing circuit which was supposedly troublesome, and a previous owner removed it. Mark's YBA200-2 will have the standard biasing arrangments. Some heads have trimpot and test points sited externally so you can do the biasing yourself with a multimeter. Boxes with 350+V or more running around inside constitute 'no user servicable parts' in my estimation.

 

[Dr_Feelgoood212]

Bueller? Bueller?

Penny? Penny? Penny?

 

[Chucky Stiletti]

This tube bias stuff ties my tiny cat brain in knots. As I understand it, smaller tube amps are often Cathode bias, where you can put in new tubes and rock on. I am less familiar with the non-adjustable fixed bias variety, which is also no muss/no fuss.

All of my tube amps are smallish guitar amps (5w to 15w). I don't own a tube bass head/combo. But it seems like the ones I have looked at suggest taking it to a tech to adjust bias, when putting a new set of tubes in them. Is this because you are typically talking about something that is more than 50w (i.e., "More power, Scotty!")?

Not necessarily. Any tube at any power can be biased in a variety of ways. What happens is that the "auto bias" type amps are class A. Class A is the most linear but the most inefficient of the classes. Many claim it sounds best because of it's linearity. Low efficiency is not a big deal in small amps, say up to about 30 Watts. It equates to bigger heavier components such as transformers and chokes. As power goes up, up to hundreds of Watts (as in big tube bass amps) the class A linearity makes for components that would make these way too heavy (an SVT head weighs 97 pounds as it is) so class AB1, class AB2 and class B are used. In these classes, the output tubes draw little or no current when there is no signal present making them more efficient and hence lighter. This "no current draw" is controlled by the bias adjustment. This adjustment literally tells the tube when to start turning on and off. Make sense?

 

[Stevis]

It will be the circuit design, not the rated output power. My YBA200 had an autobiasing circuit which was supposedly troublesome, and a previous owner removed it. Mark's YBA200-2 will have the standard biasing arrangments. Some heads have trimpot and test points sited externally so you can do the biasing yourself with a multimeter. Boxes with 350+V or more running around inside constitute 'no user servicable parts' in my estimation.

Thanks Kat and Chucky! The reason that I asked is that guitar players are always mucking around with their tubes, as part of modding their amp with super expensive NOS yesteryear RCA tubes and the like. And many guitar amps come with cheap Chinese tubes and a trip to any electronics tech is spendy. I figured that this might be the case with stock bass amps too. So, I was thinking that it would get cost prohibitive to play those games on bigger bass amps.

The small Ampeg Pf-20t/50t heads, which Jeff posted about a while back, have this feature with a light on back. You basically turn a screw until the light turns green. I haven't read any/many posts in that group about how well that works.

I wouldn't want to "blow up" a $$$ head but you could really burn through some cash with cost of good tubes AND trips to an amp tech.

Note: This isn't meant to read like I am down on tube heads. I think the tube sound is cool. It was more just me thinking out loud about the differences in some guitar and bass amps.

 

[Gaolee]

It will be the circuit design, not the rated output power. My YBA200 had an autobiasing circuit which was supposedly troublesome, and a previous owner removed it. Mark's YBA200-2 will have the standard biasing arrangments. Some heads have trimpot and test points sited externally so you can do the biasing yourself with a multimeter. Boxes with 350+V or more running around inside constitute 'no user servicable parts' in my estimation.

You can drain down the residual power with a resistor and a light bulb wired to a couple leads. The light bulb lets you know when the magic smoke is used up. The biggest offenders are capacitors. Going through and making sure all the caps are drained can be a little time consuming. Better that than the alternative. Some of the big ones in Acoustic Control amps can hold a serious charge for months, for example. Those are solid state, not valve. It doesn't matter. Where there are capacitors, there's magic smoke with teeth if you aren't careful. The big ones will kill you without even noticing.

 

[Chucky Stiletti]

You can drain down the residual power with a resistor and a light bulb wired to a couple leads. The light bulb lets you know when the magic smoke is used up. The biggest offenders are capacitors. Going through and making sure all the caps are drained can be a little time consuming. Better that than the alternative. Some of the big ones in Acoustic Control amps can hold a serious charge for months, for example. Those are solid state, not valve. It doesn't matter. Where there are capacitors, there's magic smoke with teeth if you aren't careful.

Best way to do this is to play an open E at full volume and either flick the power (not standby) switch off or pull the cord from the wall. Capacitor charge be gone!!

 

[Gaolee]

Best way to do this is to play an open E at full volume and either flick the power (not standby) switch off or pull the cord from the wall. Capacitor charge be gone!!

That's actually how I discharge the caps when I turn off the vintage Acoustic amps. I do it every time I play through them. They seem to like it, since I have had almost no need for repairs of any kind in the years I have owned them. I don't do that so much with tube amps, mostly because they are five watt guitar combos, and the caps in those aren't near the man-eaters. I still don't mess with 'em without testing first.

 

[dukeorock]

And it looks really cool when the tubes light up. You’re welcome

 

[Nocturnal]

Favorite vampire movie? I have a tie for favorite, and they're just about completely opposite of each other. Dracula with Gary Oldman because he's so talented as an actor. That guy is one of the few true thespians left in film, and it's a unique movie in look and scope. The other is Abbott and Costello Meet Frankenstein, where Bela Lugosi's Dracula has a large part. It's AnC; those guys were hilarious and the comedy still works.

Dracula with Gary Oldman was good and I agree that he is a good actor. I love the original Dracula and anything where Lugosi played the Count is good in my book. I also enjoyed the Lost Boys and Near Dark. There are quite a few others I have enjoyed but I am blanking right now.

Dumb question for you all - what's the point of a kill switch? I step on the tuner or wireless to kill the signal. A kill switch doesn't let you unplug without making an awful noise. I can't think of anything I have ever played that required the bass cutting in an out like you could do with a kill switch.

So, I'm curious - what do kill switches get used for?

I don't use pedals except for experimentation at home so a stomp box tuner doesn't work for me. I have a mute on my rack tuner and head but that doesn't mean I am always in front of it when I might need/want them. It kills the sound at the source and fills the hole where a Tone knob would have been so thats a bonus for me. The fact that I like them for my use is the only part that really matters to me. I don't have them in all of my basses but I install them on the basses I want them in. And there is little to no chance that I would use a kill switch in a Tom Morrello fashion. I'm sure there are players that don't see the need for anything beyond a volume knob you can adjust as needed. Plenty of options to go around so just use what works best for you and your situation.

 

[JJR58]

Dracula with Gary Oldman was good and I agree that he is a good actor. I love the original Dracula and anything where Lugosi played the Count is good in my book. I also enjoyed the Lost Boys and Near Dark. There are quite a few others I have enjoyed but I am blanking right now.

Gary Oldman, gotta check out, Leon: The Professional.

 

[BklynKen]

Dumb question for you all - what's the point of a kill switch? I step on the tuner or wireless to kill the signal. A kill switch doesn't let you unplug without making an awful noise. I can't think of anything I have ever played that required the bass cutting in an out like you could do with a kill switch.

So, I'm curious - what do kill switches get used for?

Not a dumb question. Just a situational thing. I don’t have one but often wish I did. I’m not always in the situation where I can simply hit my tuner pedal when I need to pull out the cable from the bass. Either I’m not close enough or I’m not using it. Having the ability to kill the signal any time I need would be very welcome. As DK said, give me convenience or give me death.