Well, we maybe loosing the plot again here....

Even the 10th harmonic, of the top frequency, is only 4000Hz and its amplitude will be many, many dB down on the fundamental.
There is filtering built into the circuits shown above, which is at least 3dB down at that frequency.
(With 1000uF output capacitor, it will also be 3dB down at 40Hz).

Why the reference to 'purpose built Bass-Guitar Speaker-Cabinets' ?
We are using 'two cheap 3 watt 4 ohm speakers'

Best hope is, they are mounted in two yogurt pots, set either side of a bent wire coat hanger, to form a pair of headphones.

 

"" Why the reference to 'purpose built Bass-Guitar Speaker-Cabinets' ?
We are using 'two cheap 3 watt 4 ohm speakers' ""
Because without reasonably similar Frequency-Response, and Distortion-Characteristics,
to the Amplifier, and Cabinet, and Speaker(s),
that will actually be use in a real Band-setting,
this project is going to be a complete and total disappointment,
and virtually useless as a practical Practice-Rig.

"Got them for free" Speakers are just not going to cut it.
.
.
.

 

"" Why the reference to 'purpose built Bass-Guitar Speaker-Cabinets' ?
We are using 'two cheap 3 watt 4 ohm speakers' ""
Because without reasonably similar Frequency-Response, and Distortion-Characteristics,
to the Amplifier, and Cabinet, and Speaker(s),
that will actually be use in a real Band-setting,
this project is going to be a complete and total disappointment,
and virtually useless as a practical Practice-Rig.

"Got them for free" Speakers are just not going to cut it.
.
.
.

Honestly.
I totally agree with you for a decent sounding well designed system.

But, back to this project...
.
.

 

Honestly.
I totally agree with you for a decent sounding well designed system.

But, back to this project...
.
.

INDEED!! This project is a PRACTICE amplifier, NOT a performance amp. Even for those gifted with vast amounts of talent, practice to "get the music right" is a requirement rather different from delivering a performance. So extended frequency response will not be part of the requirement. Likewise, a bit of distortion will not matter, so 2% THD should not be an issue. So the amplifier circuit presented would be adequate for a practice amplifier. It does need enough power to produce adequate sound from a set of free speakers, which six watts will provide with a large margin.
And it will be vastly more considerate of those in earshot than the beginner practicing with his 250 watt "seismic-bass" amplifier at full volume setting.

 

Unfortunately, it's very unlikely that we will ever get a "follow-up" reply
on how "satisfactory" this Project will ultimately turn-out to be.

I'm not guessing or assuming anything.
I've been there, done that, and completely wore-out the T-Shirt ~50-years ago.

But, it may be a good "learning-experience", so there's that part in any case.

Playing Bass through a super-cheap "Home-Stereo" bought
at a local Pawn-Shop will have much better results.
Just Plug the Bass into the "Phono" Input.
.
.
.

 

Unfortunately, it's very unlikely that we will ever get a "follow-up" reply
on how "satisfactory" this Project will ultimately turn-out to be.

I'm not guessing or assuming anything.
I've been there, done that, and completely wore-out the T-Shirt ~50-years ago.

But, it may be a good "learning-experience", so there's that part in any case.

Playing Bass through a super-cheap "Home-Stereo" bought
at a local Pawn-Shop will have much better results.
Just Plug the Bass into the "Phono" Input.
.
.
.

That is an interesting concept that has not been considered. But the electronic equipment that has a "phono" input is not likely to even be available, unless it is component stereo stuff. I have serviced radios that had a phono input, and some of the more modern ones actually used miniature tubes instead of octal based tubes. So it would be a piece of stereo equipment.

 

.

Unfortunately, it's very unlikely that we will ever get a "follow-up" reply
on how "satisfactory" this Project will ultimately turn-out to be.

I'm not guessing or assuming anything.
I've been there, done that, and completely wore-out the T-Shirt ~50-years ago.

But, it may be a good "learning-experience", so there's that part in any case.

Playing Bass through a super-cheap "Home-Stereo" bought
at a local Pawn-Shop will have much better results.
Just Plug the Bass into the "Phono" Input.
.
.
.

I believe you are right.

The thread has moved some way away from the orignal question / request.
But it gives us all a chance to nit pick make comment on other peoples ideas.

MrChips, amongst others, has had fun coming up with some circuit ideas.
(The link posted to the TDA2040 is probably the best solution, as the cct diagram is in the manufacturers data sheet).
Although it will struggle to make a couple of watts,

The last diagram (#45) has an issue with the volume control, however.

Each time it is moved, it will force the speaker cones to hit their limits caused by the DC offset.
(Pin 1 sitting around 6V).

Perhaps if he will address that and see if Snortstuff has any further input.
.

 

Unfortunately, it's very unlikely that we will ever get a "follow-up" reply
on how "satisfactory" this Project will ultimately turn-out to be.

I'm not guessing or assuming anything.
I've been there, done that, and completely wore-out the T-Shirt ~50-years ago.

But, it may be a good "learning-experience", so there's that part in any case.

Playing Bass through a super-cheap "Home-Stereo" bought
at a local Pawn-Shop will have much better results.
Just Plug the Bass into the "Phono" Input.
.
.
.

Probably not the phono input because it will be RIAA equalised giving it a 40dB bass boost.
An input for a ceramic cartridge would be the best, but that's going to be mighty rare these days.

 

The next question will be, "How do I reduce the severe distortion from this bass guitar amplifier driving my cheap speakers?"