Help adding bass to Harvard 5F10

[ES225]

I had a Harvard Tweed 5F10 clone built for me about 10 years ago and the builder did a very nice job, however, the amp always sounded to piercing and thin. Too much piercing high end and virtually no bass response. Not the warm thick tone I am looking for.
Can anyone with experience modding amps tell me what is an easy way to increase the bass response of this amp?
Increasing the value of the filter caps maybe? I already did this replacing the .022 filter cap connected to V2 to a .047 and it helped by adding gain and a bit more bass but its still not enough bass. Should I do the same to the the other .022?
The speaker is an eminence 10".
I know there should be some easy mods to get what I am needing.
Thanks for your help. I really appreciate it.

[Leo_Gnardo]

Before you start modding the amp, consider the speaker. Eminence must make a dozen or so varieties of 10 in speakers, and there are other popular brands like Jensen, Warehouse, Weber, ToneTubby, Celestion . . . but who has all of them up and ready to audition? Try whatever you can get your hands on. I'm sure you'll get some suggestions in upcoming posts too. What I find is, once you get away from spiky bright tones that overwhelm the ear, mids and lows are revealed. With that in mind, also remember your guitar (probably) has a tone control & dialing it down is sometimes all that needs to be done.

[Chuck H]

Would this Harvard happen to be a Vibro Champ from another thread? I ask because the two models share the same circuit.

Tiny amp, tiny bass. You could remove top end to give the impression of more bass in the overall balance of frequencies. The problem is that that design derives all of it's overdrive from the output. So if you change the frequency balance to favor bass then that's what you will be overdriving. That would be blatty, farty and lack harmonics and dynamics when overdriving. The design is not really suited for the changes you want without aggressive modification.

I'll mention here and on the other thread that you could always use the amp stock, run clean with the volume control lowered and then use a dirt box for your distortion. That's the only option for what you want outside of intensive circuit mods.

[Justin Thomas]

Would this Harvard happen to be a Vibro Champ from another thread? I ask because the two models share the same circuit.

Ummmm... Ya might wanna check on that...
The 5F10 is a PP 6V6 w. Cathodyne & a 6AT6 front end, 3 inputs, no trem, & I think fixed bias...

The 6G10 is an SE, basically a tweed Champ with a Tone control.

All that said, still, "tiny amp, tiny bass."

Just to avoid any confuddling.

Justin

[alexradium]

yes,the speaker can play a big role in reproducing bass frequencies,along with the output transformer,big iron equals more bass.
since this amp has the negative feedback,you could add a bass control on that line,its an old hifi trick used on Mullard amps,today it is called depth mod,basically you wire in series a cap,usually a 4n7,with a resistor in parallel,try 220k,or you can use a 1M audio pot as a variable resistor to determine how much you need and sub it lately with an exact value.

[ES225]

No this is not my Vibro Champ. I have an amp collection. As stated, this is a Harvard clone. However, it has the same problem as the Vibro Champ and the same for a Princeton I have. I hope to ask come questions about the Princeton next.
That is what I have been doing, using it clean at low volume with a distortion and EQ pedal. Sounds good that way, however I feel its a copout. They claim how great the tone is of these vintage circuits but frankly I am not getting it. I read various places on changing some caps and/or resistors to simply change the EQ of the amp just slightly. This is what I am after. There is an article online from Premier Guitar. I think its called "8 simple mods for newbies". I was hoping that someone would clarify this mod for me and point out where these components are.
I modded this amp in the last few days and it improved somewhat but not enough and now i am getting crackling noise from the tubes, which is constant. I changed the values of three capacitors by replacing them with different capacitors higher value.

[ES225]

When I got this amp it had a Jensen and talk about shrill highs on that one. So this Patriot speaker is supposed to be a darker speaker and still this amp is too bright. So it is not a speaker issue. This amp has an added NF switch to switch it in and out.

[ES225]

Strangely this Harvard has only 2 inputs, 5 tubes and it has a pot internally in the chassis, facing toward the speaker baffle. I think this is a bias pot.
If any one can identify the kit this may have come from, it would help identify it.

[Chuck H]

Ummmm... Ya might wanna check on that...
The 5F10 is a PP 6V6 w. Cathodyne & a 6AT6 front end, 3 inputs, no trem, & I think fixed bias...

The 6G10 is an SE, basically a tweed Champ with a Tone control.

All that said, still, "tiny amp, tiny bass."

Just to avoid any confuddling.

Justin

Ah! I'm thinking of the Bronco.

Harvard/Bronco ... Just got a couple of oddballs confused.

[Chuck H]

ES225,

Something to consider is that both amps, the Harvard and the VC, have very simple preamps that generate barely more gain than necessary to push the power tubes to full power plus some clipping. There is not likely any significant clipping in the preamps of either amp and unless tube stages are added there never will be. Clipping a clipped signal is what gives amps with more gain stages that saturated sound. You simply cannot get that with either of those amps in their stock topology. And I'm not saying any of this to be a buzz kill. I just want to save you chasing inevitable disappointment. Neither amp is known for big distortion and big bass. They're topologies and limited size simply inhibit either of those characteristics.

On the up side, you could consider it an opportunity to make another amp

One thing you could try to get more natural tube distortion from either amp would be to use a simple boost pedal in front of the amps to get the preamps grinding a bit. Since it's a clean signal going in it would just be the tubes in the amps doing any of the clipping.

[Justin Thomas]

I just realized: I bet most of those great distortion tones you seek from these amps were RECORDED, not live. Everyone uses them in studio, through who knows what speakers, with what effects, and with what treatments...

Justin

[Chuck H]

THAT^^^^^^^^^^^^^^^^^^^^^^^

I've been in a position to talk to a few pros about their amps, settings, effects, etc. for recordings. It's remarkable how vague they can be or how little they actually remember. And it's not any sort of secretive maneuver either. They straight up don't know or remember the details.

It's also remarkable how often the actual amp is a completely incidental part of the tone too. As in it is only being used as a clean canvas to paint a tone on with a tube driver, dirt pedal, H&K preamp, etc. At which point the amps influence on the tone is much smaller.

I have never cranked up a stock Champ and thought "Oh, hey! I can totally hear that this was the amp used in so many great recordings!" Quite the contrary. Which can only mean shenanigans. Like the signal chain is actually:

'59 Les Paul - compressor - dirt box (output not set too high) - Champ (used clean) - microphone - mixer (bass cranked up on the looped pultec eq) - to track

How much did the amp have to do with that tone!?!

[Leo_Gnardo]

THAT^^^^^^^^^^^^^^^^^^^^^^^

I've been in a position to talk to a few pros about their amps, settings, effects, etc. for recordings. It's remarkable how vague they can be or how little they actually remember. And it's not any sort of secretive maneuver either. They straight up don't know or remember the details.

It's also remarkable how often the actual amp is a completely incidental part of the tone too. As in it is only being used as a clean canvas to paint a tone on with a tube driver, dirt pedal, H&K preamp, etc. At which point the amps influence on the tone is much smaller.

I have never cranked up a stock Champ and thought "Oh, hey! I can totally hear that this was the amp used in so many great recordings!" Quite the contrary. Which can only mean shenanigans. Like the signal chain is actually:

'59 Les Paul - compressor - dirt box (output not set too high) - Champ (used clean) - microphone - mixer (bass cranked up on the looped pultec eq) - to track
ou
How much did the amp have to do with that tone!?!

That ^^^ too, and let's add what mic/mics, where are they pointed with respect to the speaker, how close (proximity effect builds bass sometimes a lot of it). How's the strip EQ set on the mix channels? Recorded on magnetic tape? That'll give you an extra hit of bass plus a dab of compression besides.

In short, your ears aren't where the mics are. And certainly don't include all the signal processing both intended and not.

[Helmholtz]

Placing a speaker cabinet directly on the floor enhances bass level.

[Dave H]

I had a Harvard Tweed 5F10 clone built for me about 10 years ago and the builder did a very nice job, however, the amp always sounded to piercing and thin. Too much piercing high end and virtually no bass response. Not the warm thick tone I am looking for.

I'd try disconnecting the tone control (just disconnect the two outside lugs). These simple tone controls bridged across the volume pot tend to add a lot of treble lift/bass cut unless the vol pot is turned up high. As a test try it with the amp vol high and guitar vol low so it's below break up then adjust the amp's tone to taste.

To add to what Helmholtz said for max bass try it on the floor in a corner a couple of feet from the walls then try it on a chair out in the open.