PUNCH - 1W amplifier

[deadastronaut]

@Gurner

Hi man...long time no ?'s...

which in your opinion would be the most efficient 9v battery amp ic then?..with an acceptable amount of vol...just curious.

rob

[tca]

... the most efficient 9v battery amp ic then?..with an acceptable amount of vol...just curious.

That is in fact a VERY good question! I guess that requires some more research... probably a class d?!?

I power the PUNCH with a 9V transformer power source,  never used batteries.

Cheers.

[tca]

At 9V supply, with a BTL IC like the TDA7052A, you can potentially squeeze about 15V peak to peak (5.3V RMS) across the load ...& in this situation that's over 700mA running through the speaker ...a 9V alkaline battery would last something like 20 minutes with the amp running full tilt!

Ok. For battery operation you could reduce current consumption by reducing the volume resistor (pin 4 to ground) and get roughly the same output power  as a lm386 (1/4W, 4mA typ. quiescent current) but with a much better frequency response.

[Gurner]

@Gurner

Hi man...long time no ?'s...

which in your opinion would be the most efficient 9v battery amp ic then?..with an acceptable amount of vol...just curious.

rob

Hi DA....I've not researched audio ICs wrt efficiency so can't really say.

BTW I wasn't saying the TDA7052A is any more or any less efficient than others (though in IMHO, most small audio ICs you see in stompbox type circuits are much of a muchness - if you seek efficiency, then a class D' audio IC is the way to go ....but try finding one of those puppies that you can solder easily in a through hole package!)...I was just pointing out that for battery purposes,  at high volumes into an 8 ohm speaker, the TDA7052A will drain a 9V battery in very short order (cos like all BTL amplifiers it gives double the voltage swing across the speaker vs. a single ended amp like the LM386)

[tca]

which in your opinion would be the most efficient 9v battery amp ic then?..with an acceptable amount of vol...just curious.

Found these two: TDA2822M and the NJM/JRC2073.

They are stereo but can be run on a BTL configuration. There are some refs here: http://www.diystompboxes.com/smfforum/index.php?topic=20509.0

Have to check for them in my local store, I will give it a try.

P.S. (edit)
They both have a typical 4mA of quiescent current, same as the LM386. ah, and the TBA820M same  quiescent current but more power and a few more external components, probably not very battery friendly.

[chptunes]

BTW I wasn't saying the TDA7052A is any more or any less efficient than others (though in IMHO, most small audio ICs you see in stompbox type circuits are much of a muchness - if you seek efficiency, then a class D' audio IC is the way to go ....but try finding one of those puppies that you can solder easily in a through hole package!)...I was just pointing out that for battery purposes,  at high volumes into an 8 ohm speaker, the TDA7052A will drain a 9V battery in very short order (cos like all BTL amplifiers it gives double the voltage swing across the speaker vs. a single ended amp like the LM386)

So.. I did a real-world test.

I have built several Punch Amps.. they are fun to build and easy to apply in different situations.  The Punch that I used for this test is on Perfboard, with an on-board 100k Volume Control (Trimmer).

Here are images of the test amp:



I opened a fresh Alkaline.. measured 9.48vDC.  Connected the battery to my test amp, with Volume Trimmer set at 100k ['just above conversation-level' output with dry guitar (single-coils)].  Current draw at idle measured 10.7mA.

Played random notes/phrases/chords for approximately 5 minutes...

Inserted my AMZ Tweed Stack Preamp and enjoyed sweet overdriven tones for approximately 10 minutes...

Unplugged my guitar, but kept the guitar lead plugged in with the test amp still 'On'.  Current draw measured 10.7mA.. went to bed...

Woke up after 7-7.5 hours, and measured voltage at 8.28vDC.  Plugged my guitar in and enjoyed 'just above conversation-level' output for approximately 10 minutes...

Unplugged from test amp.

Conclusions:  Into a 12 Ohm load, with 100k Ohms on Pin 4, battery power is very feasible for the purpose of casual 'living room' use and pedal auditioning.  Don't leave it 'On' while you sleep.  

Food-For-Thought:  My Punch still sounds fine at 8vDC.. the TDA7052A chip will operate down to 6vDC.

-Corey

[petey twofinger]

i plan on building a few of these . one would definitely have to be be battery powered . i would like something mall for utility testing and monkeying around . i have some nicad "c" cell sized batterys from cordless drill packs , then also a few AA holders that would un up to 9 volts i think one that is 12 volts as well . i am thinking those AA would outlast a typical  nine volter .  for my larger battery amps i use sla 12 volt cells .





i wonder what chip the dano honey tone uses ...

oh look , how about that , a tda7052

http://music-electronics-forum.com/attachments/8184d1266908743-ht-circuit2.jpg

thank you for taking the time and effort to do that test sir ... i got a little nervous , now i feel a little better .

[Gurner]

Conclusions:  Into a 12 Ohm load, with 100k Ohms on Pin 4, battery power is very feasible for the purpose of casual 'living room' use and pedal auditioning.  Don't leave it 'On' while you sleep.  

My earlier 'battery sump' warnings relate to the tda7052A at full output swing...i.e. full power  (which on a 9V battery will see about 16Vpp across the speaker) ...without knowing what type of voltage levels you're experiencing across the load with a 100k on pin 4, it's difficult to predict how much stress there is on the battery. Also your 12 ohm speaker helps significantly (16 ohms is even better) ...but most will likely connect up an 8 Ohm speaker, which will see battery life reduced.

FWIW, you'll get approx 5 times longer battery life with 6 x AA acting as 9V (vs.a PP3 9V battery).

[tca]

i wonder what chip the dano honey tone uses ...
oh look , how about that , a tda7052
http://music-electronics-forum.com/attachments/8184d1266908743-ht-circuit2.jpg

Oh, I didn't know that!

Cheers.

P.S.
The HoneyTone is powered by a 9V battery.

[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.

[tca]

I like that cab! What is it? What is inside?

[chptunes]

My earlier 'battery sump' warnings relate to the tda7052A at full output swing...i.e. full power  (which on a 9V battery will see about 16Vpp across the speaker) ...without knowing what type of voltage levels you're experiencing across the load with a 100k on pin 4, it's difficult to predict how much stress there is on the battery. Also your 12 ohm speaker helps significantly (16 ohms is even better) ...but most will likely connect up an 8 Ohm speaker, which will see battery life reduced.

Just measured voltage across the 12 Ohm Load:  25.7mV DC.

[PRR]

> random notes/phrases/chords for approximately 5 minutes...
> overdriven tones for approximately 10 minutes...
> ..amp still 'On'.  Current draw measured 10.7mA.. went to bed... 7-7.5 hours
> 'just above conversation-level' output for approximately 10 minutes...

I don't understand. 5+10+10 = just 25 minutes actual playing?

I wanna go way out in the woods and play all night. Hiking back to the house every hour or two for a new batt misses the point.


Another point: the 8 + 4 loading wastes 2/3rd of your precious power. It would be more efficient to change to 1/3rd the supply voltage: 3V battery.

Or, since 3V is "small" re: silicon drops, change from bridge loading to simple single-end at 6V.
______________________

> the most efficient 9v battery amp ic then?

"Efficient" battery audio requires you *define* your goals. (And don't pre-assume stuff like voltage.)

Maximum power must be *just barely enough* for your purpose. An efficient 1 Watt amp is a very inefficient 0.1 Watt amp. (This is where digital really helps, but is DIY-adverse.)

You don't hear Watts. You hear sound. The difference is the speaker. For a given sound level, an eight 12" stack needs a lot less power than a 3" toy-speaker. If serious about battery, start by being serious about speaker. (Yes, carrying a full-stack into the woods is awkward, I might prefer a smaller speaker and a pocketful of extra batts.)

THEN define a power level. For "kinda loud" in a small speaker, maybe over a Watt. For conversational level in a good efficient speaker, 0.1 Watts may be ample.

Right-sizing the amp is more important than trying different chips.

Right-sizing means being flexible about battery type.

Anyway C- and D-cells are MUCH more cost-effective than 9V batts. (I think 9V batts were promoted by the battery companies. A 4-AA pocket radio runs a long time, weak battery sales. 9V batts give just-tolerable life and frequent battery sales.)

________________________

The LM386 was a fine amp, but has fallen into the gutter of low-low-low-cost fabrication.

The LM380 has the "advantage" of being (AFAIK) discontinued, so the stock you find is from National circa 1978, good stuff.

Both are critical about layout and that R-C network on the output.

[tca]

About the LM386 and the LM380...

Both are critical about layout and that R-C network on the output.

I've learned that the hard way!

[quackounet]

Nice, I think i'll try to make one with the volume pot,
what jfet can i use in subtitute of the MPF 102 or 2N5457 ? they don't seems to be available anymore.

[tca]

Nice, I think i'll try to make one with the volume pot,
what jfet can i use in subtitute of the MPF 102 or 2N5457 ? they don't seems to be available anymore.

I think the 2N5457 will work just fine.

[chptunes]

> random notes/phrases/chords for approximately 5 minutes...
> overdriven tones for approximately 10 minutes...
> ..amp still 'On'.  Current draw measured 10.7mA.. went to bed... 7-7.5 hours
> 'just above conversation-level' output for approximately 10 minutes...

I don't understand. 5+10+10 = just 25 minutes actual playing?

I wanna go way out in the woods and play all night. Hiking back to the house every hour or two for a new batt misses the point.

Another point: the 8 + 4 loading wastes 2/3rd of your precious power. It would be more efficient to change to 1/3rd the supply voltage: 3V battery.

I'm up to about 40 min of play-time on the same battery now.. Those first sessions were only what I documented before and after leaving the amp 'On' for 7+ hours.  I'll try to update this thread when this battery is exhausted.

I am wasting power intentionally, right.. to achieve a desired volume level.  Makin' the Punch fit my needs.. Ya know.  Should I feel guilty about wasting a few mV.?..

I don't like camping.

..and yes, the typical JFETs will work great.  I use 2N5457 as much as possible.

[quackounet]

Thank you, but it's the same for the 2N5457 (when i look on mouser), i'll try my luck in a local store ,
No other common jfet ?

[chptunes]

Radio Shack sells MPF102.  Small Bear sells J201 and 2N5457.

www.smallbearelec.com

[quackounet]

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.. :/