PUNCH - 1W amplifier

[tca]

Thank you, i'll order there then when i'll start it,
I order from europe so i always try to find common component in local store when i only need a few of them, with the  additional vat and shipping fee it can be very expensive for only a few parts.. :/

Try http://www.musikding.de/

[quackounet]

Thank you tca, i don't see them there, but they have other part i often need and shipping are really low, it'll be very handy thank again

[blackcorvo]

Just tested the TDA2822M, one channel, with the same power source that I use to power the PUNCH. The sound is similar, very clean and loud and overdrives nicely! Going to use the TDA2822M chip to make a stereo monitor for my PC. Even if one uses the TBA820M in bridge mode it still outnumbers the components of the PUNCH!

Cheers.

Any chances of giving us a schematic for the TDA2822M circuit? I can't find the TDA7052 in my town, but they have the other one by the buckets.

[davent]

I think for the power amps, the circuits are just being taken from the datasheet, i haven't checked back to see.

This one has examples for using it in stereo as well as bridged mono.

http://www.st.com/web/en/resource/technical/document/datasheet/CD00000134.pdf

[B Tremblay]

Here are my notes from late 2004, when I was looking for an improvement over the Ruby while retaining the option of battery power:

IC amp notes

Of the ICs offering approximately 1W output:

Headroom (best to worst)
TDA2822/TDA2003
- Ruby @ min. Gain -
TBA810
TDA7052
NJM2073
- Ruby @ max. Gain -
TBA820M

Volume (best to worst)
NJM2073
TDA2003
TBA810
TDA2822
TBA820M/TDA7052 (tied)
- Ruby -

Parts count (lowest to highest)
TDA2822/NJM2073 (pin-compatible)
TDA7052
- Ruby -
TBA810 (kit)
TDA2003 (kit)
TBA820M

Noise (lowest to highest)
TBA810
TDA2822/Ruby @ min. gain (tied)
TDA2003
TDA7052
NJM2073
TBA820M

Ghosting (least to most)
TBA810
TDA2822/Ruby (tied)


PART NUMBERS
Within these notes, the part number TDA2822M DIP-8 is referred to simply as TDA2822. The TDA2822 series is also also available in a DIP-14 package, with extra ground pins used for heat sinking. It is not known at this time whether the DIP-14 produces higher output with an identical circuit, but the datasheet does include 9v/8Ω specs that are not listed for the DIP-8.


POWER
Supply voltage: 12v (via filtered AC adapter)

When supply voltage was changed to 8-AA battery pack (measuring around 10.5v), a very slight decrease in background noise was noted.

Lower voltage power supplies were tested: 9v, 6v, 3v. At 9v, the volume was not much less, but headroom suffered. Distortion was noticeable when playing power chords with the neck pickup selected. 6v saw more distortion and a slight drop in output. A 3v supply provides only distorted low output.

Quiescent current draw is quite close for both ICs.

CIRCUIT
Standard FET buffer at circuit input with 10k-B pot (Volume) to 1k series resistance at IC input.

With identical test circuits, the NJM2073 is louder and seems to have more gain (presenting as distortion) when operated at the same volume setting as the TDA2822. More noise accompanies the increased output level of the NJM2073.

TDA2822 retains more headroom over range of Volume pot rotation than the NJM2073.


A simple low-pass filter was placed between the buffer output cap and the Volume pot. The filter has a knee of 5.3khZ.


Three different Zobel networks at the speaker output were tested, with no discernible difference.


12v is recommended for maximum headroom and output. I believe that as a 12v battery pack loses voltage, the output level will stay reasonably stable until 9v. Then, volume will drop and distortion will increase.


A faint distorted ghosting is noticeable as single notes decay with the TDA2822 The same phenomenon was noted with the Ruby. The TBA810 does not exhibit the ghosting. I cannot definitively state that this is a chip-related issue. The speaker may be playing a role here.

Here's the 2073/2822 circuit I worked with:

[tca]

Just tested the TDA2822M, one channel, with the same power source that I use to power the PUNCH. The sound is similar, very clean and loud and overdrives nicely! Going to use the TDA2822M chip to make a stereo monitor for my PC. Even if one uses the TBA820M in bridge mode it still outnumbers the components of the PUNCH!
Cheers.

Any chances of giving us a schematic for the TDA2822M circuit? I can't find the TDA7052 in my town, but they have the other one by the buckets.

Just use the schematic from the datasheet and add the buffer.

Cheers.

[tca]

Here are my notes from late 2004, when I was looking for an improvement over the Ruby while retaining the option of battery power..

Thanks for sharing your notes.

[chromesphere]

Hey guys, i BB the punch a few nights ago and it sounded great!  The only problem is its pretty quiet.  I didnt have time to check over my layout but im 99% sure it was ok.  Anyway, i recorded a video of it if your interested in hearing it.  Its really easy and there are no oscillolation issues like the LM386 (amongst others )
Cheers
Paul

[tca]

The only problem is its pretty quiet.  I didnt have time to check over my layout but im 99% sure it was ok.

It should not be so quiet and it is too dirty for my ears. Are you using a fresh battery? Did you try a 9V transformer?

[chromesphere]

The only problem is its pretty quiet.  I didnt have time to check over my layout but im 99% sure it was ok.

It should not be so quiet and it is too dirty for my ears. Are you using a fresh battery? Did you try a 9V transformer?

Hmmm, thats weird.  Ill check it over again when i get some time and see if there are any errors.  I slapped it together quickyl, its a bit mental at my house at the moment, probably stuffed something up.

Paul

[chptunes]

Cool vid.. I'm not surprised by the low output.  The TDA7052A chip is quieter than the TDA7052 chip.  I love it's output level.. just perfect for the living room/bed room.

But, mine does sound a lot cleaner than yours.  With just a dry guitar plugged in, mine stays clean'ish.  What speaker did you use for that vid?  Maybe some of that saturation is the speaker.?..

-Corey

[chromesphere]

Cool vid.. I'm not surprised by the low output.  The TDA7052A chip is quieter than the TDA7052 chip.  I love it's output level.. just perfect for the living room/bed room.

But, mine does sound a lot cleaner than yours.  With just a dry guitar plugged in, mine stays clean'ish.  What speaker did you use for that vid?  Maybe some of that saturation is the speaker.?..

-Corey

Hey Corey!  Hmm, so it might be the right level...i forgot to show the speaker in the video but its basically just a 6inch 8 ohm hifi speaker.  Im pretty sure i had it in series with another hifi speaker (could have been about 5 inch if i had to guess.

Prehaps mine was dirtier then yours because of the guitar pick ups?  My guitar is a gibson sg.  I wouldnt say they are very high output pick ups but they have a bit of punch.

The output is good dont get me wrong. I can pretty much crank it and not wake up my baby boy

Paul

[tca]

My guitar is a gibson sg.  I wouldnt say they are very high output pick ups but they have a bit of punch.

I guess this is the reason why!

You must try and power it with a 9V transformer... that will awake up your family!

Nice vid.

Cheers.

[chptunes]

My guitar is a gibson sg.  I wouldnt say they are very high output pick ups but they have a bit of punch.

I guess this is the reason why!

You must try and power it with a 9V transformer... that will awake up your family!

Nice vid.

Cheers.

I agree with tca.  My Esquire has a traditional single-coil in the bridge.

Your level would be louder with a single 8 Ohm loudspeaker, like a 10" or 12" Celestion or Weber.

With a big speaker, I hear less saturation and more headroom.

-Corey

[Gurner]

Prehaps mine was dirtier then yours because of the guitar pick ups?  My guitar is a gibson sg.  I wouldnt say they are very high output pick ups but they have a bit of punch.

The output is good dont get me wrong. I can pretty much crank it and not wake up my baby boy

So is it still dirty when you roll down the SG's vol pot?

depending where the DC vol pin resistance is set, there could be up to 60x voltage gain (i.e. the maximum voltage gain for the TDA7052A)

At 9V you can work on the TDA7052A outputting about 7.4V clean.

therefore 7.4/60 = 123mV ....anything about that voltage arriving at the TDA7052A input will clip (which is just about all guitars on the initial pluck)

[chromesphere]

Hey guys!  TCA the voltage into the punch was from a 9v power pack, so i think we are good there.

Thats why i mentioned the SG (could have been a stronger output signal).   I'll have to try rolling off the volume and checking the voltage on the volume control pin as well, not sure when thats going to happen at the moment though as things are a bit unsettled at our house at the moment.

Anyway, i might not retire this one yet and mess around with it some more when i get sometime.

Paul

[chromesphere]

Just a follow up on this.  Had a few mins to mess around with it this afternoon.  Firstly i had a 47nf cap instead of 4.7nf in the input.  didnt make much difference, but removed some muddyness.

I wanted to see if increaseing the voltage to 12v would give some more volume so i added a couple of aa batteries in series.  With the extra 3v's its much better imo. sounds much punchier, pun intended

I think im going to power this thing on 12v's.  It sounds much better imo!  Give it a try!

Oh yeah, and decreasing the vol on the guitar cleans up the output, so its a matter of extra signal into the chip thats clipping it.

Paul

[chromesphere]

So I decided to have another crack at the pump amp.  Built up the vero and I think it was working ok.  Housed it in a small tin.  That's when I started to lose my mind.  Im getting a rustling noise.  its pretty random, but I can make it happen when I shake the tin.  Also the output is very muffled.  And when I turn my guitar volume on, on the last, approx, 5% of the turn there is a large volume on the speaker (so much that you can see it move out quite dramatically).  DC on the speaker?

If I use my power filter with the dc adapter, I just get this bup bup bup bup bup sound.  I have to turn the volume down to about 10% on the punch amp before I can hear anything that sounds like guitar.  Same with a battery. 

I have checked it over a million times...it looks like its wired up fine....?

Any help would be greatly appreciated.
Paul

[tca]

Check the connection of the jack of the speaker, it must be isolated from ground. It SHOULD NOT be connected to ground, this is a BTL amp. It does get hot if one of the outputs (pin 5 or 8 ) is connected to ground? Check the temperature of the chip (use your finger ). In cases like this, the chip may be destroyed. You should compare with a fresh one.

Cheers.

[chromesphere]

In frustration I pulled it out of the tin.  (definitely not connected to ground now!) still had the same problem.  The chip doesn't get hot.

I thinking all the strange noises are coming from my guitar.  They get worse on the quieter pick up them they do on the stronger pick up nup it crackles even without anything connected!


Heres voltages of the chip and jfet:
1 - 9.07v
2 - 2.51
3 - 0
4 - 1.1
5 - 4.4
6 - 0
7 - 0
8 - 4.4

g 1.7
s 9v
d 1.3v

This is on max volume (500k)

it crackles and pops...like cocoa pops :|

Paul