Help me improve this amp

[taviii]

Hi guys, I'm currently finishing a 1watt amp, i will laid the schematichs and some pictures below.
The amp sounds surprisingly good, nice clean sounding amp, I'm using two 4" speakers in parallel. They're rated 8ohms 6watt.

I would like to know a way of adding a little more volume, and also add a tone control, it lacks some trebble in my opinion.

[Marcos - Munky]

First thing: get rid of the battery and use a dc power supply. You'll find out pretty soon that amps and batteries aren't a good combination. Amps draw a good amount of current.

2nd thing: to improve volume, you can feed the amp with a higher voltage. This TDA can handle up to 18V. Try something like 12V or 15V.

3rd thing: I woudn't add a tone control, at least not a passive one. Passive tone controls will drop your signal, so you'll get less volume output. You can indeed add an active tone control or even a comprete preamp to this amp, but I think the goal of this one is to be a nice and simple amp. One thing you can try is to lower that 470nF cap. I'd try a 100nF or 47nF cap.

[11-90-an]

if you can make another one of your schematic and use one to boost the input+ and use the other to boost the input-, apparently it would become a 2 watt output i think...

[taviii]

Im powering the amp with a dc wall adapter (9v).
I will try higher voltages.

One thing you can try is to lower that 470nF cap. I'd try a 100nF or 47nF cap.

Surely will try this, what changes will this make?

[taviii]

if you can make another one of your schematic and use one to boost the input+ and use the other to boost the input-, apparently it would become a 2 watt output i think...

I like how this sound but not a single clue on how to do it 

[antonis]

Search for "Bridge amplifier" ..
(but with 9V single supply I'd suggest you not to bother too much..)

[taviii]

Search for "Bridge amplifier" ..
(but with 9V single supply I'd suggest you not to bother to much..)

What voltage will be more suitable to try this option?
I have a 13.6v transformer laying around.

Update. I changed the b100k volume pot for a b500k and the volume increased pretty much to what i want know. Is this normal?
After playing a little with the amp i find that it kind of saturates when playing a heavy chord at full volume, which doesn't happen whit the 100k pot, same thing when i added some fuzz at full gain. Could this be the speakers? Maybe a bigger speaker would be able to handle it? Or is a limitation from the basic circuit?

[11-90-an]

Ok... drew a little preamp and tone control to put before the 1 watt mini amp schematic 
Uses a JFET preamp and AMZ's stupidly wonderful tone control 3



never got around to the bridge amplifier thing... i couldnt find a input- of the tda7052a chip... i think the other folks will correct me soon enough...

Oh and also... C1 in my schem can be 100nF or higher...
In the 1 watt mini amp schem, change the 470nF cap to 4.7uF or higher... 

[Marcos - Munky]

A bigger speaker will give you the sensation of more volume.

While you can indeed use two of those on bridge configuration to get twice the output power, keep in mind doubling the output doesn't mean doubling the loudness. From the way our ears hears the loudness, if you plot a graph of power x loudness, you won't get a linear curve, but a log curve.

What that means? Basically, doubling the power doesn't double the loudness. But multiplying the power for 10 will double the loudness. Yeah, you need a 10W amp to get twice the loudness of a 1W amp (assuming you're using the same speakers for both). So, going from 1W to 2W probably won't do too much.

This amp isn't intended to be loud and great, it's intended to be a simple, quick/easy to build and nice amp for bedroom practice and effects testing. Exactly what you already got. While you can improve it by adding a preamp with a full tone stack, it'll probably be too much work for a design which was made to be simple. I would keep it as it is, and start to search for a bigger amp to build.

[11-90-an]

A bigger speaker will give you the sensation of more volume.

While you can indeed use two of those on bridge configuration to get twice the output power, keep in mind doubling the output doesn't mean doubling the loudness. From the way our ears hears the loudness, if you plot a graph of power x loudness, you won't get a linear curve, but a log curve.

What that means? Basically, doubling the power doesn't double the loudness. But multiplying the power for 10 will double the loudness. Yeah, you need a 10W amp to get twice the loudness of a 1W amp (assuming you're using the same speakers for both). So, going from 1W to 2W probably won't do too much.

This amp isn't intended to be loud and great, it's intended to be a simple, quick/easy to build and nice amp for bedroom practice and effects testing. Exactly what you already got. While you can improve it by adding a preamp with a full tone stack, it'll probably be too much work for a design which was made to be simple. I would keep it as it is, and start to search for a bigger amp to build.

This post would have been a good preliminary to mine....

[taviii]

Ok... drew a little preamp and tone control to put before the 1 watt mini amp schematic 
Uses a JFET preamp and AMZ's stupidly wonderful tone control 3

thanks man! i will try your preamp, do i need to power it separately from the amp power source?

In the 1 watt mini amp schem, change the 470nF cap to 4.7uF or higher... 

will do! what effect does the cap value has?

This amp isn't intended to be loud and great, it's intended to be a simple, quick/easy to build and nice amp for bedroom practice and effects testing. Exactly what you already got.

yes i understand, its a great little amp!
the amp sounds louder with the b500k vol pot, the sound fills the room nicely now, but the speakers saturate at full volume either when i strum a ¨big¨ chord or when i add fuzz at full gain. i thought that maybe a bigger speaker would be able to handle it with no saturation or dampness.

could you recommend a bigger amp schematic?

[11-90-an]

>do i need to power it separately from the amp power source?
nope... just use whatever power supply you are using for the 1 watt mini amp scheme 

>will do! what effect does the cap value has?
higher value = more bass (there are some exceptions)
Sometimes this also affects volume...(or what we percieve to be volume...)

>could you recommend a bigger amp schematic?
If you can make another 1 watt mini amp board and power your other speaker with it... Should give a little bit more fullness I think..

[taviii]

>do i need to power it separately from the amp power source?
nope... just use whatever power supply you are using for the 1 watt mini amp scheme 

>will do! what effect does the cap value has?
higher value = more bass (there are some exceptions)
Sometimes this also affects volume...(or what we percieve to be volume...)

>could you recommend a bigger amp schematic?
If you can make another 1 watt mini amp board and power your other speaker with it... Should give a little bit more fullness I think..

great! thanks a lot, i will try those changes today.

amp loudness is great now, i just need to take the volume down when i use a dist/fuzz pedal or when playing heavy at full volume.

[Marcos - Munky]

could you recommend a bigger amp schematic?

How much bigger?

But, as I said, it also depends on the speakers. Once I built a LM386 amp (1/2W or so), easy to play at full volume on a 5" speaker. On a 4x12 cabinet, it was loud enough for bedroom playing and a bit too loud to play at night. So a suggestion is to test this amp with a bigger speaker.

I must say your cabinet is so beautiful. If building a whole new amp to put in it it's an option, I have a suggestion for you. Take the Alembic F2B, which is basically the tube preamp from a Fender amp, and build a JFET version of it. You'll have a gain pot, volume pot and a complete tone stack, plus a Fender-like clean sound. You'll need a power amp to complete your amp, which you can use the TDA7052 again. With the Alembic preamp, you'll also probably get a little volume boost. I may have the layout for the JFET Alembic at home, so I can do a quick layout of the whole thing if you're interested.

[taviii]

I may have the layout for the JFET Alembic at home, so I can do a quick layout of the whole thing if you're interested.

for sure im interested! im somewhat new to electronics so the layout will help me greatly!

on the cabinet, i work as a furniture maker welder/carpenter so i have many offcuts of wood and metal laying around, i can build a cabinet like that real quick.

[Marcos - Munky]

This is how the complete layout looks:


The board is 3.60 inch x 1.30 inch, with all pots soldered to the board, so the only wirings are for the in jack, speakers and power supply.Because the pots are as close as possible, you can fit small knobs but won't be able to fit a bigger knob.

Let me know if you need any adjustment like the space between pots or something else. Also, pm me your e-mail so I can send you the pdf files.

[taviii]

Let me know if you need any adjustment like the space between pots or something else. Also, pm me your e-mail so I can send you the pdf files.

You are awesome! Thanks for the help!

[11-90-an]

Just thought about it now... the tda7052 seems to increase volume when resistance to ground is increased...that would explain why increasing your 100k pot to 500k increased volume just for test, try putting a 1M resistor to ground instead of a pot, or even try disconnecting it altogether..(disconnecting would imply infinite resistance to ground)

I recommend moving the volume pot to the output of the tda7052, it gives more overall control...

[anotherjim]

This chips datasheet shows a 1M control pot, but note that this is adjusting a current flow in the chip and the data is with a supply of just 6v. The data also shows a 1uF cap across the pot, but I think this is only to keep the control smooth when the power supply has high ripple/noise.

The TDA7052 already is a bridge amplifier. The tell from the outside is the speaker wires each going directly to the chip. If it was a normal single-ended amp, there would be a coupling capacitor and only one speaker wire (the other wire to 0v). For this chip, you cannot connect either speaker wire to 0v.

If you have an 8ohm speaker, you will be exceeding the chips rating already at 9v supply. 16ohm will be more comfortable.

As already said, more speaker is the way to go for more apparent volume - and use proper guitar speakers at that.

If you add a guitar amp style pre-amp (Fender/Marshall tone stack) you can get a better tone - but those have a characteristic mid-scoop response which will actually reduce apparent volume with clean settings. If you like the more mid-heavy "Desert" sound, keep the design as it is.

[taviii]

I recommend moving the volume pot to the output of the tda7052, it gives more overall control...

Nice i will try moving the volume pot.

If you have an 8ohm speaker, you will be exceeding the chips rating already at 9v supply. 16ohm will be more comfortable.

As already said, more speaker is the way to go for more apparent volume - and use proper guitar speakers at that.

I have two 8ohms 6watt speakers in parallel, so load will be 4 ohms?
I'm powering with 9v and 13.6v. Maybe i should wire them in series to get 16ohm
What difference would it make? Energy consumption? Or it does affects sound also?

If you add a guitar amp style pre-amp (Fender/Marshall tone stack) you can get a better tone - but those have a characteristic mid-scoop response which will actually reduce apparent volume with clean settings. If you like the more mid-heavy "Desert" sound, keep the design as it is.

Im gonna build another one with preamp, im curious about how will it sound.
With volume control pot at 500k is loud enough. I'm surely need to try it with a bigger speaker to see if it can handle a fuzz/distortion at full volume.