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Bassman 100 too 'clean'

#21
hennessybass said:
You might also try a jumper cable. Bass into ch 1, input 1... jumper cable from Ch 1, input 2 -> ch 2, input 1. This will give you a second gain stage. Crank the vol on ch 1, and you will be hitting ch 2 hard. Crank ch 2, and you will be hitting the master double hard. Same idea as a clean boost. This gives you some additional EQ options as well.
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It sounds like you're saying the two channels will cascade i.e., Channel one will drive channel 2, if you jumper them.
That is not a stock set up (although you can have your amp modified to do that.)
In all of Fender's original two channel amp designs the two channels are parallel, not series. So jumpering the two can give you the combined voicings of both channels - as long as they are in phase. Many of the BF and SF Bassmans have an extra triode gain stage on the Bass channel, so its output is out of phase with the Normal channel.
 
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#22
b/o 402 said:
It sounds like you're saying the two channels will cascade i.e., Channel one will drive channel 2, if you jumper them.
That is not a stock set up (although you can have your amp modified to do that.)
In all of Fender's original two channel amp designs the two channels are parallel, not series. So jumpering the two can give you the combined voicings of both channels - as long as they are in phase. Many of the BF and SF Bassmans have an extra triode gain stage on the Bass channel, so its output is out of phase with the Normal channel.
Click to expand...

correct but on those models there are only 2 preamp tubes and by using both channels you use another tube. whereas one channel only uses one tube. the blackface used 4 preamp tubes 2 per channel, so in essence by using both channels on a silverface you get the same tone as the blackface by utilizing both tubes. also you get the added EQ and color of the other channel.
 
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#23
hennessybass said:
If you are playing into an 8ohm cab, they you are essentially lowering the "watts" of your amp. You are not getting full power, which should contribute to an earlier breakup.
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Unless I'm misunderstanding what you're saying, it sounds like you're talking about a solid state amp (which will put less power into higher impedance loads).

A tube amp like the Bassman will put full power into whatever cab you connect it to, it's just that if the cab doesn't match what the head wants to see, you'll wear your tubes faster and run the risk of damaging the amp. But you won't get less power, in any case.
 
#25
b/o 402 said:
It sounds like you're saying the two channels will cascade i.e., Channel one will drive channel 2, if you jumper them.
That is not a stock set up (although you can have your amp modified to do that.)
In all of Fender's original two channel amp designs the two channels are parallel, not series. So jumpering the two can give you the combined voicings of both channels - as long as they are in phase. Many of the BF and SF Bassmans have an extra triode gain stage on the Bass channel, so its output is out of phase with the Normal channel.
Click to expand...

Now I know. I get that ch 1 would not "drive" channel 2,,, but would using the volume of both channels, drive the output section harder?
 
#26
morgan138 said:
Unless I'm misunderstanding what you're saying, it sounds like you're talking about a solid state amp (which will put less power into higher impedance loads).

A tube amp like the Bassman will put full power into whatever cab you connect it to, it's just that if the cab doesn't match what the head wants to see, you'll wear your tubes faster and run the risk of damaging the amp. But you won't get less power, in any case.
Click to expand...

A lot of tube amps have multipul taps on the output... like the SVT, which has 4 and 2. Or the V4B, which has 2,4, and 8... using the different taps allow you to match your amp and cab and get the full power from your amp.

The Fender has a 4 ohm tap only,, so when you run it into an 8 ohm cab, there is a mismatch, and you are not getting full power. So in this case, it is actually like a solid state amp that just has one output.
 
#27
cman808 said:
I recently acquired a mid 70s silverface Fender Bassman 100 -- for me, it sounds too clean for my liking, and I can't get it to break up at all (note: I'm playing either a 70s hagstrom or jazz bass, and using a 410 cab). Are there any changes I can make (ie: changing tubes, phase inverter, etc..) to change this, or am I stuck with this clean tone? Nothing wrong with clean tone, but I was hoping for a sound similar to a V4B and the like
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I have the same amp and you need to put a tube screamer on that puppy.
 
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#28
markjazzbassist said:
correct but on those models there are only 2 preamp tubes and by using both channels you use another tube. whereas one channel only uses one tube. the blackface used 4 preamp tubes 2 per channel, so in essence by using both channels on a silverface you get the same tone as the blackface by utilizing both tubes. also you get the added EQ and color of the other channel.
Click to expand...
Ok here's the schematic of the 100.
Invalid Link Removed
And here's the BF:
Invalid Link Removed
Note that besides the extra gain stage, the R and C values in the tone control circuit are completely different from the normal circuit.
Bottom line, although the two channels are in phase on the 100 (sorry, my bad), you are probably not getting as much gain out of the Bass channel as on the AB165 models.
 
#29
b/o 402 said:
Ok here's the schematic of the 100.
Invalid Link Removed
And here's the BF:
Invalid Link Removed
Note that besides the extra gain stage, the R and C values in the tone control circuit are completely different from the normal circuit.
Bottom line, although the two channels are in phase on the 100 (sorry, my bad), you are probably not getting as much gain out of the Bass channel as on the AB165 models.
Click to expand...

no argument here, just saying you're utilizing both tubes instead of 1 which will impact the tone so it's not a negative sum gain. plus you gain the gain, bass, treble (mid too depending on which channel you use) to add to your tonal shaping, meaning channel jumping does do something, it's worthwhile to try.
 
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#32
markjazzbassist said:
no argument here, just saying you're utilizing both tubes instead of 1 which will impact the tone so it's not a negative sum gain. plus you gain the gain, bass, treble (mid too depending on which channel you use) to add to your tonal shaping, meaning channel jumping does do something, it's worthwhile to try.
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Absolutely! Just not going to get one channel driving the other, unfortunately.
 
#33
If the bias was still in the correct range but on the cold side it should still distort.

Likewise yes its a 4ohm tap on the output transformer. And the ratio that transformer is wound to would make a 2000ohm impedance for the 6L6 quad. Pretty normal for Fender quads.

So running the amp at 8ohms that quad is running at 4000ohms.

It should still distort though lol. But if you pull 2 tubes 4k is just right for a pair. I really hate pulling tubes though. Defys the purpose really.

I still don't understand , run 100s through countless cabinets the thing breaks up way before full volume.
 
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#34
I have a 61 bassman and a 65 Showman I changed the output transformers in both to mercury magnetics so I could switch
the Ohm's. The amp with the stock transformer is set and if the Ohm's dont match the tone is not as good. It is a big improvement in tone and volume they may not breakup to your liking at which point you may need a pedal
 
#35
One man's too clean is another man's too dirty.

When I think of dirt, I like that subtle, on the edge, touch sensative type thing... other guys stack three fuzz pedals. It can be hard to get a baseline of what guys really have in their head on the internet.
 
#38
I had that same model from that era and once I put volume over 7 she gave me that extra grit. ( not too much though)
Also though I was playing a P bass too with a slightly over wound pick up.
 
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#39
hennessybass said:
One man's too clean is another man's too dirty.

When I think of dirt, I like that subtle, on the edge, touch sensative type thing... other guys stack three fuzz pedals. It can be hard to get a baseline of what guys really have in their head on the internet.
Click to expand...
I'm talking clean like super clean, even when digging in, attacking with a pick, etc... I've tried my hagstrom, J bass, and a EB-3 copy (still has the growl of a Gibson) -- all sound super clean, which is why I'm thinking there's something going on with this amp (from what others are saying)
 

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