Smoother overdrive tips for bassman..

[lenniepickit]

OK - so I'm getting pretty happy with my tone tweaks on this 5f6a and am looking for a way to smooth out the O.D. as I start to turn this baby up. I'm running stock values through out and have changed coupling caps to mallorys. First I'm wondering if just switchin the rest of the orange drops on the board will help and then second I'm looking for other spots to look at besides getting into the big caps under the chassis..

Thanks again!

[selloutrr]

Sprague Orange drops are harsher then other tone caps. It's a good start. Tube selection should help with smoothing out the rest.
resistor brand and type can also play a role.

I wouldn't change the filter cap values under the pan. that is more for shifting low end response.

got to bounce to a dog show hope it helps.

[lenniepickit]

Great - thanks - just wanted to be sure I wasn't wasting my time before starting...

And I just realized that I had not had the NFB connection connected to the 8ohm speaker tap - does this mean I wasn't getting the NFB there?

Would unhooking my NFB all together help give me that smoother od I was looking for?

[mmmoser]

You should definitely hook up the NFB circuit to the speaker tap. Then you can judge the effect on the tone. The circuit was designed to use the NFB in place.

[ampgeek]

I have built a dozen or more 5F6As of various flavors over the last five years and have found that splitting the V-1 cathode reduces "flabbiness" which provides a much tighter OD tone to my ears.

Knocking down the V-1 cathode bypass cap(s) also provides a significant reduction in the flab. I usually run 10 uf on the normal channel and 0.1 to 5 uf on the bright side in split cathode plans.

I also run both V-1 triodes in parallel so I can dial in a bit of the normal channel with a bit of the bright channel.

Of course, a nice, tight OD pedal makes a huge difference in OD tone. I only play small, dive bar venues and can never turn this circuit up high enough to get true power tube crunch unfortunately.

Finally, your speaker choice will have a significant impact on overall tone as you probably already know. I have developed a fondness for Weber alnico Bluedogs and Silverbells. One of each in a 2X12, partially open back cab makes a nice "little" package.

Good luck!
Dave O.

[lenniepickit]

Great bunch of info ya'll - thanks!

So yeah I feel like I just got a ton of headroom hooking up that NFB and ampgeek you just answered a mess of questions I'd been mulling over. The big one was if I needed to reluctantly start saving for the Alnico instead of the cheaper Ceramic Blue Dog but the clips I heard over at Weber and the I'm hearing in my are telling me to save the extra dough and go for the Alnico..

Of course if anyone can weigh in on the blue ceramic/5f6a combo I'd love to hear about that too

[Alexo]

I've got a ceramic blue dog and it's usually too smooth to my ears in most places - might actually be what you're looking for! But if you're currently using new speakers, be sure to let them break in for 40 - 80 hours before judging the amp too 'harshly.'

NFB is a strange thing. Depending on the power tubes, imo, with 6V6's or EL34's, other naturally smoother tubes, the amps can sound smoother (in some regard) with no nfb than with. But with 5881's, the output section can sound harsh and strident without nfb. But I've gotta say that true NOS USA Tung Sol 5881's don't suffer that issue so much.

[lenniepickit]

I'm looking for a good excuse to get the cheaper ceramic Blue Dog first and that smoother sound may indeed be the one I'm looking for lol..

I've got a WGS Greenback in there right now that is my fav sounding speaker with it it yet. Daniel over there said it would be fine unless it's dimed but I'd like to not blow up one of my fav speakers lol

BTW I've got a multi-tap OT on this and have tried a V30, CL80, Wharfdale, and my Em. Lady Luck pulled from my epi cab was is surprisingly the second best option so far....

[tubeswell]

Would unhooking my NFB all together help give me that smoother od I was looking for?

No! keep the NFB!

I had a M8's '59 Bassman LTD on the bench for repairs a couple of months ago. It was weak and distorted. One side of the OT was fried because the output tubes hadn't been replaced in ages and it was being thrashed at the blues club regularly.

So I replaced the OT with a Mojo OT, added 1k5 grid stoppers to the 5881 sockets (put a new pair of 6P3Se in), and it was still sounding a bit shrill and ice-picky unless the presence was completely cut, but... then I remembered reading something in the NFB chapter in Merlin's 1st book about this and lo and behold I put a 100pF speed-up cap in parallel with the NFB resistor, and voila! Perfect!

So try the speed-up cap 1st.

[lenniepickit]

Thanks tubeswell and all the rest of ya'll - this amp is sounding soo much better since getting advice here and I've done some reading one speed up cap and have it ready to try out but the fan is in bed so I guess we'll have to wait till later

I think I've got the fever here though so I'm sure I'll be dreaming tone again tonight lol...

[lenniepickit]

Wow - just got a few minutes in before work - I have to say getting that NFB on the correct tap has reeeally pulled this amps together - it's sounding amazing!

[ampgeek]

Right on Lennie!! Welcome to the addiction. But...don't forget the reason why you are doing it. Play...play..play...and..enjoy!

Quick question: Was this a kit or a scratch build?

Cheers,
Dave O.

[Buschman]

The 5f6a can be used a bunch of ways. Try diming the volume knobs but turn all the tone knobs all the way down. Then barely ease in some treble, mid, and presence to taste. New 10s can be a bit harsh also. Let a bass player play the amp for a month.

[rogb]

To give him this crazy amount of pleasure, you need to learn and master some male orgasm techniques.The significant problems we have cannot be solved at the same level of thinking with which we created them.

LOL

Kyle you are a crazy SOB, but I luv ya

I'd love to see one of your builds...

[wicker]

'smooth' often reffers to more scoped highs tones, you could try adding extra cap between signal path and ground, for example vol pot out and ground, start from 47p and go higher (I would even start from 120p).