The Fender Super Bassman 300 thread

[rodl2005]

Just wait till you plug in 2 MATCHING 410 Fender neos. It'll be even more huge.
I've said it b4 with regard to my 115 Bassman cabs. 2 is more than twice the.... errr .. everything.
But it's very rare I ever need em both. That's fer sure.

 

[Down_Low]

I’d like to make more use of the duel channels on my Bassman, however I hate having to run the foot switch - it’s one more cable I have to run to my pedalbord. Does anyone know if a wireless or Bluetooth channel switch exists? So a small stompbox on my pedalboard, and a receiver to plug into the back of the Bassman?

 

[rodl2005]

I only know of the Berg's B|Amp Bluetooth footswitch

 

[PotsdamBass8]

I’d like to make more use of the duel channels on my Bassman, however I hate having to run the foot switch - it’s one more cable I have to run to my pedalbord. Does anyone know if a wireless or Bluetooth channel switch exists? So a small stompbox on my pedalboard, and a receiver to plug into the back of the Bassman?

The guitarists I play with use a snake for their pedalboards since they use effects both before the amp and in the loop. This might make things easier? Get a footswitch with a separate cable and make the cable part of the snake.

 

[Paul M]

I have one orange light on the automatic bias display. 2A. The manual says, "LED is orange: The tube is wearing out and should be replaced with a new tube with the same tube rating." Does this mean I can replace just that one tube? Being a matched set, I would have thought all six output tubes had to be replaced. I know next to nothing about vacuum tubes.

 

[Rocksolid]

I have one orange light on the automatic bias display. 2A. The manual says, "LED is orange: The tube is wearing out and should be replaced with a new tube with the same tube rating." Does this mean I can replace just that one tube? Being a matched set, I would have thought all six output tubes had to be replaced. I know next to nothing about vacuum tubes.

Every now and again I get one on start up, I play a few notes and it goes green. Did yours stay yellow?

 

[rodl2005]

I'd read thru the manual and ..... probably..... buy one or 2 new matching 6550s to whats in there.
Iirc, Ruby tubes have an ID number system written on em, (or am I mistaken? ) and if so, ya should be able to buy a couple of matches power tubes.
I'm not in any way experienced with replacing power tubes. I've really only ever replaced the whole lot at once.
Contrary to "popular" belief, I've not had to fully retube my amps perhaps more than twice In my playing life. ..altho I've had many all tube amps, I usually don't run em that hard and the power tubes last a good long time

 

[rodl2005]

Every now and again I get one on start up, I play a few notes and it goes green. Did yours stay yellow?

Good Point! I take a quick look at the lights, but use my age old method of.... if it sounds good, it is.....

I'd surely keep an eye in it, and check it out properly if the light stays orange, otherwise, I'd just keep an eye on the actual tube.

 

[flatwound62p]

Mine is at the tech at the moment. I had 1A and 3A glowing orange but changing to green after a couple of minutes. That went for about 6 weeks and eventually they stayed orange so I put it in for a service.
I can't understand the matching pairs part of the manual either. The tech is the local authorised Fender man. I'll hit him up for a clear explaination when I'm picking it up.

 

[Rocksolid]

Mine is at the tech at the moment. I had 1A and 3A glowing orange but changing to green after a couple of minutes. That went for about 6 weeks and eventually they stayed orange so I put it in for a service.
I can't understand the matching pairs part of the manual either. The tech is the local authorised Fender man. I'll hit him up for a clear explaination when I'm picking it up.

Awesome. Be interested to hear what he says.

 

[Paul M]

Every now and again I get one on start up, I play a few notes and it goes green. Did yours stay yellow?

Last night the orange light was steady all through rehearsal. I tried it again today and it was still there. Then I shut it off and turned it on again in stand by mode. I think this allowed the auto bias to do its thing. I took it out of stand by mode and all the lights were green. This was a good wake up call to prepare for the day when I will need to buy replacement tubes.

 

[rodl2005]

If I remember correctly, the manual says to turn onto standby for a bit, then turn on, but either leave it in mute mode, or without a signal for another minute.... Ice watched the lights on mine in this minute, and they cycle thru.... I think is the biasing etc... I really dunno, but I DO do this. Seems ok for mine.

 

[Tim1]

I love this amp, but have always wished Fender had never used an auto-bias system, or if they did that it had no lights to worry about. This despite never having had a problem with it in either a 100T or the SB300. Years of playing tube heads without auto bias systems and without ever having power tube issues makes me wonder why they bothered. Just something else to confuse and obsess with, and there must be thousands of old silverfaced Bassmans around still working fine without it.

 

[rodl2005]

I don't mind either way... I use em as a rough guide only.
And, if it sounds good etc... is "how I roll"
If I did see orange lights etc... I'd still just see if it sounded ok still, if it did, I'd check em again at end of set.
Am using it tonight actually, with the HG410...corporate gig EASY access

 

[flatwound62p]

Does seem the auto bias is a bit of a hassle in some ways. My tech is swapping my chip out for a newer version because it's a known problem. Hat goes off to Fender Australia for supplying it free, even though the amp is over two years old and I'm not the original owner which are both "end of warranty" reasons in Oz.
I like the idea that if one tube goes bad half way through a gig the auto bias shuts that pair down and you can keep on rocking with no damage to the rest of the amp.

 

[Tim1]

Does seem the auto bias is a bit of a hassle in some ways. My tech is swapping my chip out for a newer version because it's a known problem. Hat goes off to Fender Australia for supplying it free, even though the amp is over two years old and I'm not the original owner which are both "end of warranty" reasons in Oz.
I like the idea that if one tube goes bad half way through a gig the auto bias shuts that pair down and you can keep on rocking with no damage to the rest of the amp.

"Known problem" for the 100T but far, far less of a problem with the SB300. This was dealt with way earlier at the start of the thread as apparently it is slightly different in the SB300 so not really an issue. IIRC someone who was in the know explained it all back then. It was however quite an issue with the early 100Ts.

 

[flatwound62p]

I ran that past him, that I'd heard about 100T issues but not the same with SB. Answer was that some early SBs had a problematic chip. Like you, I was surprised to hear it but I don't reckon Fender would donate a new bias chip without good reason.

 

[Tim1]

I ran that past him, that I'd heard about 100T issues but not the same with SB. Answer was that some early SBs had a problematic chip. Like you, I was surprised to hear it but I don't reckon Fender would donate a new bias chip without good reason.

Agree on that, I am in New Zealand so same deal applies. Still surprises me that Fender would replace a chip with no issues. Certainly an offer that is not common, otherwise everyone would demand a replacement chip. My SB300 was, I believe, the first to turn up down here and I have never had an issue.
Would still be quite happy without the autobias though

 

[flatwound62p]

Got my amp back from the tech and managed to get a rundown on things.

First off, clarification on my bias circuit. I misunderstood what he was saying. Mine actually had a problem and needed replacing, Fender supplied a new one free because it is a "known issue". Not like I said previously that it was junked and replaced without reason. My bad

He ran me through the theory of replacing SB tubes in pairs and this is how I understand it ...

The tubes operate in two groups of three, 1A 2A and 3A on one side and 1B 2B and 3B on the other side. The two sides need to match one another to operate properly, the thing that needs to match is called mutual inductance. The amp should leave the factory with all six power tubes close matched, but over time they will drift out of spec. The auto-bias circuit compensates for the drift but only up to a certain point, when one or more tubes drift too far off spec it can no longer compensate. This is when you get orange and red lights showing.

Mutual inductance is the thing that is measured when sellers grade tubes. So when they refer to a pair being of "the same grade" they are saying they are matched for mutual inductance.

If you need to replace one tube because it's drifted too far off spec or it just goes bad, you need to replace it's partner as well. Both new tubes need to be matched for mutual inductance in order to keep the TOTAL of the two A and B sides matching.

This is also the reason for the tubes being fused in pairs. Eg if 2A suddenly has a problem ... the fuse for the 2A and 2B pair will pop, switching off the pair. That way the total mutual inductance for both sides stays matched and the amp can continue to operate.

I've done my best to translate what I was told and it's giving me a headache , I'm a looooong way from being clued up on this stuff myself.

 

[rodl2005]

Here's my auto- bias lights last Sunday.

I wouldn't have bothered with em at all, but this discussion prompted me to check.
I was set up close to the rear wall, so I couldn't get me head in behind to see, so I stuck my phone in and took a pic.
All green, all GO, and it sounded superb too.
Thru the HG410 too

This pic was the night before, but same set up.