Fender Bassman 100T Chapter 3

[mattwear]

Please correct me if I'm wrong but I've not read anywhere that there's digital signal processing in either the 100T or SB300. A lot would have been written about it had there been any. Could be wrong but to my best understanding it's an analogue path throughout. The speaker simulator could just be High/low pass filtering.

 

[Levitamin]

Please correct me if I'm wrong but I've not read anywhere that there's digital signal processing in either the 100T or SB300. A lot would have been written about it had there been any. Could be wrong but to my best understanding it's an analogue path throughout. The speaker simulator could just be High/low pass filtering.

I didn't think so either, but when I see the words "simulation" it raises my hackles. Just curious, how would a high/low pass emulate a speaker?

 

[Freight Train]

I've been trying out a Bassman 100T recently. I've read a lot of posts in these threads, but not all of them. Forgive me if this has been addressed already. Is the "speaker emulation" in the silent record mode some kind of digital modeling? What about in the OD channel, which Fender describes as "modern?" Is this a 100% tube amp, or is there anything else going on?

The speaker modeling affects only the DI output in "post" position, which is post power tubes. It is not a bad thing, it's simply eq'ing the DI output (and yeah, it might be a digital eq - don't know, don't care) so you get a curve emulating what you'd expect from a well-mic'd speaker cab. It only effects the DI output, nothing else.
The "modern" OD channel is only modern in the sense that it has active eq, and the eq is solid state analog. But the OD channel still has a tube vibe - it uses the same 12AX7 (V1) as the passive channel for its first stage, but it has a solid state final stage whereas the passive channel uses the other half of V1 as its final stage. However, the OD channel can be "more tube" than the passive channel. On the OD channel if you set gain to 0 (if you want a clean sound) and blend on 10, you are now going through 3 tube stages in the preamp - one half of 12ax7 V1 as the first input stage, and both halves of 12ax7 v2 in the overdrive circuit - whereas the passive channel has two tube stages - one half of V1 as the first stage, the other half of V1 as the final stage.
Personally I think you're stressing over nothing. Having active solid state stages, or even dsp, in the preamp section is not going to make a tube amp suddenly sound digital. The real key to the sound of a tube amp is the power tubes imo. Solid state power amps with tubes in the preamp just don't sound tube to me. But add a tube power amp to a solid state or digital preamp and you've got a tube sound.

 

[beans-on-toast]

Just curious, how would a high/low pass emulate a speaker?

Software speaker emulators, such as Invalid Link Removed are often specific EQ settings modeled on a cabinet, some implementations more complex that others. The popular Radial DI has a speaker simulator which is a simple high and low pass circuit network.

Hardware speaker emulators that simulate a speaker with resistors, capacitors, and inductors do exist. Some even use what is called a speaker motor, a speaker coil and magnet that emulates much of a real speaker, but not fully. But these need additional EQ to emulate the speaker cabinet contribution.

 

[Levitamin]

The speaker modeling affects only the DI output in "post" position, which is post power tubes. It is not a bad thing, it's simply eq'ing the DI output (and yeah, it might be a digital eq - don't know, don't care) so you get a curve emulating what you'd expect from a well-mic'd speaker cab. It only effects the DI output, nothing else.
The "modern" OD channel is only modern in the sense that it has active eq, and the eq is solid state analog. But the OD channel still has a tube vibe - it uses the same 12AX7 (V1) as the passive channel for its first stage, but it has a solid state final stage whereas the passive channel uses the other half of V1 as its final stage. However, the OD channel can be "more tube" than the passive channel. On the OD channel if you set gain to 0 (if you want a clean sound) and blend on 10, you are now going through 3 tube stages in the preamp - one half of 12ax7 V1 as the first input stage, and both halves of 12ax7 v2 in the overdrive circuit - whereas the passive channel has two tube stages - one half of V1 as the first stage, the other half of V1 as the final stage.
Personally I think you're stressing over nothing. Having active solid state stages, or even dsp, in the preamp section is not going to make a tube amp suddenly sound digital. The real key to the sound of a tube amp is the power tubes imo. Solid state power amps with tubes in the preamp just don't sound tube to me. But add a tube power amp to a solid state or digital preamp and you've got a tube sound.

Thanks for the input. I put a quad of NOS GE 6L6s in the Bassman, so it does sound excellent.

 

[Levitamin]

So I just picked up a used Bassman 115 Neo cab for the 100T. Right away I'm noticing some crazy vibration noise inside the amp! I think it might be the choke, but I'm not sure. Anybody else have this kind of issue? I also notice that the front panel on the cab does not hold on securely. It's also vibrating loudly. The rig sounds absolutely fantastic with the amp to the side, and the panel pulled off though. This might be the best bass rig I've ever owned, and I've owned at least a dozen.

 

[rodl2005]

Dunno re the amp I'm sorry. The 115 neo cab''s grille should be fastened securely. .mine sure are. It is just strong velcro holding it on tho

 

[Levitamin]

Dunno re the amp I'm sorry. The 115 neo cab''s grille should be fastened securely. .mine sure are. It is just strong velcro holding it on tho

Yeah, it rattles no matter how hard I try to push it on

 

[rodl2005]

Yeah, it rattles no matter how hard I try to push it on

Sounds like something got bent outta shape or summink. I'd just try pressing on different areas of the grille see if you can isolate it. If it ain't rattling when the grille is off. ..must be something simple

 

[Levitamin]

Sounds like something got bent outta shape or summink. I'd just try pressing on different areas of the grille see if you can isolate it. If it ain't rattling when the grille is off. ..must be something simple

I just don't think the velcro is holding very well. I'm more concerned about the rattling in the amp

 

[Freight Train]

I just don't think the velcro is holding very well. I'm more concerned about the rattling in the amp

Inside the 100T

I just don't think the velcro is holding very well. I'm more concerned about the rattling in the amp

I somehow missed that the rattling is coming from the 100T! I know mine on the 410 has never made any sort of mechanical noise in 5 years of stage use, but then again I don't crank a lot of lows at all. But I'm sure plenty here do and if it was a chronic problem someone would have brought it up before. That's annoying. Have you had someone give it a close ear while you're playing to figure pinpoint it's coming from?

 

[NOLA Bass]

Heading into the studio tonight. What is anyone's thoughts on the silent recording mode vs a mic on the cabinet (in my case the Fender NEO410).

 

[frankzelf]

Heading into the studio tonight. What is anyone's thoughts on the silent recording mode vs a mic on the cabinet (in my case the Fender NEO410).

From experience, they both will sound great!
But actually preferred the D.I. out..

 

[NOLA Bass]

From experience, they both will sound great!
But actually preferred the D.I. out..

Going di for simplicity factor w isolation.

 

[Levitamin]

Inside the 100T

I somehow missed that the rattling is coming from the 100T! I know mine on the 410 has never made any sort of mechanical noise in 5 years of stage use, but then again I don't crank a lot of lows at all. But I'm sure plenty here do and if it was a chronic problem someone would have brought it up before. That's annoying. Have you had someone give it a close ear while you're playing to figure pinpoint it's coming from?

The rattling is really bad at modest volume (3 on the master) at 25 watts. I'm pretty sure it's the choke, but it doesn't feel loose. I've had to put the head to the side to record for the time being. I didn't have this problem at all with the amp straddling my Bag End S15-D.

 

[Freight Train]

The rattling is really bad at modest volume (3 on the master) at 25 watts. I'm pretty sure it's the choke, but it doesn't feel loose. I've had to put the head to the side to record for the time being. I didn't have this problem at all with the amp straddling my Bag End S15-D.

??? That I don't understand at all. Granted cabinets will resonate at different frequencies but at lower volumes that's surprising.

 

[rodl2005]

True. Sounds like a problem for sure. You say it doesn't have the rattle when on a different cab? Have you tested the amp while it's off? Give it a bit of a shake. .. report back. As far as the cab is concerned. .. I'd be going over that with a fine toothed comb. Ain't too many things that Can rattle. .

 

[Levitamin]

True. Sounds like a problem for sure. You say it doesn't have the rattle when on a different cab? Have you tested the amp while it's off? Give it a bit of a shake. .. report back. As far as the cab is concerned. .. I'd be going over that with a fine toothed comb. Ain't too many things that Can rattle. .

I've moved the amp around while it's off. Nothing seems loose at all. I've checked the tube cans, and screws inside. Nothing. Before, I had the 100T straddling a Bag End S15-D. It was way too wide for that cab, so I sold it in favor of the neo 115. It seems like it should have rattled like crazy on the Bag End, though. The body of the head was resting on the cab, not the rubber feet. There were no vibrations at all. I'm really surprised that this is happening with a cabinet that was designed to go with this head.

I bought both the head and cab used, so maybe people were selling them because of the rattles?? The cab sounds great with the grill off, and I'll take the head to a tech after the new year and see what we can do.

 

[Levitamin]

??? That I don't understand at all. Granted cabinets will resonate at different frequencies but at lower volumes that's surprising.

I know. It's really weird.

 

[SteveFromBerlin]

GT tubes are the bottom of the barrel like Ruby.
You will never know how good your amp will sound until you do some tube rolling. It is so easy with the auto bias.
Reliability and tone mean a lot to me. I look at it like putting cheap regular gas in a high performance car. Sure it will run but you will not know it's full potential until you put some good premium gas in it.
It took a while but I settled on a combination that gives me more clean headroom and a nicer break up. I like to run mine on the hot side and that puts more stress on the tubes.

Hej män, would you mind sharing your combination of tubes you swapped? I'm interested in the nicer / more gradual breakup. Cheers from Berlin, will be comparing my 800 to the 100T today!