Making a fender bassman 300 a 100w@?

[Pikasoll]

I`ve got an fender bassman 300 tube amp. There are six 6550 power tubes 50w each driving the amp.

I was wondering if it is possible removing four of the tubes and use only the two remaining as 100w.

Any thoughts?

[T-Bird]

Hi.

I haven't worked on that amp, but IIRC it's not possible to do so.

And generally such an odd impedance can't be found on "normal" OT's.

AFAIK, it's possible to do a mod that allows You to remove pairs from the circuit, without physically removing them.

Regards
Sam

[billfitzmaurice]

Originally Posted by Pikasoll

Any thoughts?

Yes. Why? Trying to save on the electric bill?

[Freddels]

Do a search on here. I believe there are some that will remove 2 tubes and run it as a 200 watt amp. But that doesn't help with the weight. Fender should make a 200 watt all tube amp and try to get it in the 55-60 lb range.

[JimB52]

I think the 300's power tubes are arranged in 3 pairs. I recall reading something in the manual about how a pair (or two) could fail and the remaining pair(s) would continue to function, so I think the short answer would be yes, but like Bill said, why?

[jastacey]

The 300 has 3 fuses next to the output tubes, these are used to protect the 3 pairs of output tubes, you probably could pull the fuses ,but you also have the issue of mismatched impedances placed on the output transformer

[Pikasoll]

Might sound lame, but i`m only using the amp as a practise amp in my house at the moment. I was just thinking on saving some tubes that way. I`m not gonna buy another amp or sell the fender bassman 300. It`s a lovely amp

[Pikasoll]

Originally Posted by jastacey

The 300 has 3 fuses next to the output tubes, these are used to protect the 3 pairs of output tubes, you probably could pull the fuses ,but you also have the issue of mismatched impedances placed on the output transformer

I`m no electrician, but if I pull a fuse, does that mean I should switch the impediance switch from 8 to 4, or if it`s on 4, then switch to 2.

Has anyone tried that with their bassman 300?

[JoshuaTSP]

100w will still be really loud, and I don't think you'd really be saving any tubes.
Rather, wearing out a pair of tubes before the rest.....creating a mismatch.

[christw]

I use my SVT-II at home and don't worry about tubes. It'll be fine. Pulling the tubes is too much work to be practical. Plus 100w is still really loud, especially through the right cabs.

[Chasarms]

Originally Posted by Pikasoll

Might sound lame, but i`m only using the amp as a practise amp in my house at the moment. I was just thinking on saving some tubes that way. I`m not gonna buy another amp or sell the fender bassman 300. It`s a lovely amp

I know of tube amps that are 25-30 years old with the original tubes. Yes, tubes fail, but with the amp not being pushed they will last a long time assuming everything else is correct with the amp. There's no reason to attempt to save tubes.

[BassmanPaul]

Originally Posted by Pikasoll

I`m no electrician, but if I pull a fuse, does that mean I should switch the impediance switch from 8 to 4, or if it`s on 4, then switch to 2.

Has anyone tried that with their bassman 300?

That is possible for an amp with four output tubes. yours has six so if you put one set your impedances will change by a third. This will cause a mismatch endangering the other four tubes. If the amp ain't broke please do not try to "fix" it. Use it as it was designed.

[Mr. Foxen]

Just get a practice amp. Not worth the risk and the messing about.

[edot3021]

Buy a Bassman 100.

[Coolhandjjl]

After reading numerous tutorials from the assorted tube guys, here is my take:

If you want a specific tube sound like a tube amp running flat out wide open, you have to run the tube amp flat out wide open, period. If it's too loud, you can't just remove tubes, or put lower value tubes in there. Doesn't work.

One way to do this is with an attenuator.
http://www.eurotubes.com/euro-weber.htm

There are limits to what it can do however. Don't expect to be able to create great 'power tube break-up sound' running at quiet levels. You'd really be better served by having a range of tube amps at assorted outputs from very low to high.

[JimB52]

Practicing at home with the 300T, I make the second channel preamp tube break up, and keep the master vol. at '1'. Sounds OK.

[will33]

Originally Posted by edot3021

Buy a Bassman 100.

+1



http://www.arsenmusic.com/knowledgeb...er_bassman.jpg

[Coolhandjjl]

Originally Posted by JimB52

Practicing at home with the 300T, I make the second channel preamp tube break up, and keep the master vol. at '1'. Sounds OK.

Supposedly there's a sound quality difference between pre-amp tube break up and power amp tube break up. The cab would have a lot to do with it as well.

[Thumpking]

I have both a Fender 300 PRO and a 78 Bassman 100 for that very reason.