5F6A Settings

Gris

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Anyone here play a lot thru a tweed Bassman? I’ve started playing more thru mine and am interested in what settings you use. I jumper the channels, but haven’t settled on vol/vol, treb, bass, mid, presence settings. Thanks.
 

JRapp

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Depends what you want...there are two different tone stack circuits; the early .02/.02/250/56K and the later BF style tonestack values (as used in the RI). I favor the early one as it's more guitar-friendly and I keep the tone settings around 3.5 for bass, 7 for treble and middle, and presence as needed. All bets are off for the later tone stack as I don't have much use for it.
 

Gris

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8655A8E8-F961-4DCE-9F2F-F42797F26C3D.jpeg
Mine is not a reissue…
 

The Ballzz

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Anyone here play a lot thru a tweed Bassman? I’ve started playing more thru mine and am interested in what settings you use. I jumper the channels, but haven’t settled on vol/vol, treb, bass, mid, presence settings. Thanks.

Depends what you want...there are two different tone stack circuits; the early .02/.02/250/56K and the later BF style tonestack values (as used in the RI). I favor the early one as it's more guitar-friendly and I keep the tone settings around 3.5 for bass, 7 for treble and middle, and presence as needed. All bets are off for the later tone stack as I don't have much use for it.

The settings @JRapp mentioned are pretty darned close to what I would expect, for a 5F6-A or even an early style Marshall, although the speaker(s) used can make dramatic differences! :eek: What I use as a "litmus test" for almost any amp (not that I will necessarily use it for that amp all time) is my '72, Marshall 1960B, 4x12, with well worn G12M/25 watt/75 hz speakers. Given that I've been playing through it a whole lot since 1974, I'm intimately familiar with all characteristics of it's sound and it is an excellent control constant for testing amps. It is wired to allow 16Ω or 4Ω use or even just two speakers at 8Ω. It helps give me a clue as to what other speaker or speakers may be most complementary for any given amp, or whether the amp just sounds like Doo-Doo!

This looked almost new when I got it in '74:

IMG_2070.jpg


In that pic, it was doing duty as a split 2x12+2x12 for a wet/dry rig. Sounded fabulous, but was simply "Too much monkey business for me to be involved with!"



Also NOT A Reissue! :D
Gene
 

Antoon

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I have a couple of typical settings on a 5f6a Bassman, depending on the guitar and how clean I want it to sound. And what speakers I am using.

With Tele neck pickup treble on 8, mid on 3, bass always on 0 and presence on 2. 50/50 mix of the bright and normal channel. Volumes at 6 or 7.

0.02uf/0.1uf/100k tonestack.
 

JRapp

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Easy enough to tell which circuit it is---right there on the board. Most of the early ones have the .02/.02 bass and mid cap values, later ones went to .1/.02 pretty consistently. To me, they're like two different amps. Why they picked those values (among other things) for the RI is beyond my understanding.
 

SoK66

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Easy enough to tell which circuit it is---right there on the board. Most of the early ones have the .02/.02 bass and mid cap values, later ones went to .1/.02 pretty consistently. To me, they're like two different amps. Why they picked those values (among other things) for the RI is beyond my understanding.

If I recall correctly those were the values they found in the one they reverse engineered for the RI. Most of the originals I'ver been into had the same values as a reissue, but if I build a clone or gut & rewire a reissue I use the schematic values.
 

King Fan

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Interesting discussion, y'all, thanks. In my limited understanding it would be extremely common for Fender to build an amp differently on the shop floor than they'd drawn it on the schematic.
 

Axis29

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I have a Reissue... But, I had to re-wire it, so I did it to the 5f6-a schematic. Does that qualify? LOL

Seriously, the differences between the Reissue and the schematics have been gone over a million times. Fender reverse engineered an original Bassman. A bunch of the later originals came out with the same component values. Some folks swear by the changes, others swear at them. I don't have enough real experience with both versions to make a decision one way or the other. I DO know that I love my Bassman as it is...

I've been using my Bassman a lot recently. I've owned it since 2015, rewired it a couple years later (I goofed a trace doing a cap job, and just decided to gut it). I replaced the (GZ34 style) SS rectifier with a Weber Copper Cap SS rectifier. But, I went with a WR4 which emulates a 5R4 tube and lowers the voltage inside the amp. I also run a 12ay7 in V1. For speakers, I have a mix of 2 Jensen P10Rs and two Eminence 1028ALKs. I rarely jumper the channels. Mostly just laziness there, though. LOL

I honestly fiddle with the EQ knobs every room it goes into... But, it's usually pretty minor tweaks. One thing I do find, as the volume goes, the bass control usually comes down a little. I just went and looked though... Bright Vol: 7.5 Tre: 5 Bass: 4.5 Mid: 5 and Pres: 5. Huh? That was after band practice in my living room last Sunday (I'm in a five piece with a sax... Never really realized how loud horns are). I never would've imagined the EQ was set so 'flat'. But, there it is.
 

gabasa

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There was a time years ago when I relentlessly was looking at vintage tweed Bassman for-sale-ads just to see the pics of the circuits inside. I probably saw pics of ~50 different 5F6A amps and every single one had the 100k/0.1/0.02 tone stack. I think that the 56k/0.02/0.02 was also in the 1957 5F6 schematic, then in 1959, the production change might have come out soon after the new 5F6A schematic release so the schematic version would be quite rare. Not sure.

Regardless, I've tried both tone stacks ad nauseam back in the days when I had a collection of Traynor Bass Master amps (which were well-built Bassman clones) and I much prefer the schematic values. I've found that with them, the dark channel is generally well-suited to single coil guitars and the bright channel is perfect for PAFs, but either channel can still be used for either type of guitar and the amp still sounds great. The balance from one channel to the next is great. The later 0.1uf versions are too thin and bright for my tastes.
 

Antoon

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One may prefer the schematic values but I would say the 100/0.1/0.02 tonestack is THE 5f6a bassman sound.

But you are right, it is a bit more scooped and hollow sounding.
 
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Antoon

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This thread sparked my interest in the 5f6a tonestack again and tonight I put both options on a switch. I tried for about half an hour to go back and forth, with various control settings, to see which one I liked most. I must say that I have not made my mind up yet. It is quite a difference, the schematic values are quite a lot more mid rangy, and more 'normal' sounding. You cannot make one sound like the other with just the controls. But I believe that the great sound that this YouTuber Millstap gets from his 1960 is definately the 100k/0.1/0.02 version.
 

gabasa

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This thread sparked my interest in the 5f6a tonestack again and tonight I put both options on a switch. I tried for about half an hour to go back and forth, with various control settings, to see which one I liked most. I must say that I have not made my mind up yet. It is quite a difference, the schematic values are quite a lot more mid rangy, and more 'normal' sounding. You cannot make one sound like the other with just the controls. But I believe that the great sound that this YouTuber Millstap gets from his 1960 is definately the 100k/0.1/0.02 version.
I also believe that the100/0.1/0.02 is the best known 5F6A sound without a doubt. That's great that you did that, is there any chance you can post a sound sample that illustrates the differences you're hearing? (Hint: this would make a great YouTube video)! Let us know how you feel after you spend some more time switching back and forth. Thanks for that.
 

Antoon

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I will see if I can do a short sound clip with a looper. Not sure you will be able to hear the difference though. Biggest difference to my ear is obviously a different mid content, but also that with the schematic values, the mids are the first that start to distort if you turn up the volume. They have a big influence on the overdrive tone of the amp. That is probably why Fender filtered these frequencies out, I guess. But both setups sound good to me.

With the 100k/0.1/0.02 tonestack there seems be a bit more headroom without the mid-rangy distorted mush. Definitely more blackface sounding as well. But I suppose it is very dependent on how the amp/speaker handles these distorted mid frequencies. Perhaps 12" speakers do a little better than the low powered 10" Bassman speakers in this respect.
 
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Gris

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haven’t really fiddled w spkrs yet. Right now it has a couple of OLD Jensen alnicos in it, a P12N & a P12P
 

Antoon

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In my amp a have an extra spst switch left for an optional setting. I was fiddling around with the TSC and doing listening tests with different component values. Currently the switch reduces the value of the treble pot (with a parallel resistor) to simulate a lower value treble cap. That moves the mid dip a bit up, to resemble a Marshall tonestack, and gives a cleaner and leaner sound (for lack of a better word). A nice option to have. Another option would be a different slope resistor (=100k now).

Another option would be a higher treble cap (or higher treble pot value). The value of the treble pot is almost exactly 250k in my amp and I have found the amp to be extremely sensitive to a higher value of the treble pot (e.g. by placing a series resistor before it). I could not reproduce this change with the TSC to the extend of what I was hearing. A 10k resistor already gave me a huge increase in high-mid and high frequencies, while the TSC only predicted an extra 1 db or so.

Normally the 250pf mica caps have a low tolerance but not the pots. A Bassman with a 260k or 270k treble pot will sound quite different than one with a 250k treble pot.
 

63 vibroverb

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Highly recommend a 12AU7 in the cathode follower tube slot (V2, middle preamp slot). To my ears, it sweetens up the EQ section and just makes the whole range of the controls nice on the ears. Basically makes almost any settings sound good, just a matter of pick your favorite piece of the pie. Doesn't hurt to try.
 

Antoon

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Highly recommend a 12AU7 in the cathode follower tube slot (V2, middle preamp slot). To my ears, it sweetens up the EQ section and just makes the whole range of the controls nice on the ears. Basically makes almost any settings sound good, just a matter of pick your favorite piece of the pie. Doesn't hurt to try.


Interesting. Never heard of this. It would be difficult to mount this "mod" on a switch though, so a subtle change would be hard to notice. Do you have any idea what actually happened electronically? I have the impression that the 5f6a Bassman does not like too much preamp gain.
 




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