Audio Amplifier 10706NB - Rockwel(l)

I drew this up some time ago.

Yep. Thats the sort of thing, but the OP could use the derived 1/2VCC for the TDA2030 as well as the TLO72, no sweat.

martin

days

audio

Just wondering where Phil is...........

martin

Actually, I'd buffer both inputs with 1/2 072 ea, then passively mix from 10k audio taper pots with say 22k Rs on the wipers. Virtual grounds are fine as long as you're careful with that node.

Graham

days

Gain's rather high for a guitar pickup and input Z @ 100k is a bit low.

Sort of ok otherwise. I'd prefer a zener derived 1/2 rail bias since power rail modulation from the power amp will feedthrough as VLF into the signal otherwise

Graham

I'm sure he'll stick his oar in soon enough and criticise eveything in sight.

In passing, I was thinking there may be a better device than the 072 for low voltage operation. Maybe the TLC272 ?

Graham

On my diagram I have two parts, TLC071 series and the OPA134 series.

greg

saw that Just wondering, if you increase the R from point A(from memory), to say 1Meg, does it affect the geetar sound. Havent done much with guitar preamps, but they seem to be no more than impedance converters, really.

In my short lived studio days, I really hated going into "the Studio" where the musos lived, to fix a problem. Ohms law does not exist in The Studio

martin

voltage

Don't have a clue, just been trying to set up a spanish RS account, got lost,doesnt work in Spanglish, but just heard of a 32m^2 shop/office/ drug dealing center/ for rent in the Old Town, for a

100?/ month.

Be nice to get a little w/shop setup that isn't in an industrial estate, close to the cafe's etc

martin

Oh, I read it as TL071.

Actually TLC072 would be fine here. It's actually quieter than the TL072.

Mind you with Vs max @ 16V I wonder if that isn't going to be a problem with an unregulated 12V wall wart. I wouldn't be surprised if they can get to 18V off load.

An OPA is overkill for a guitar amp though ( but solves the Vs problem ). OK maybe an OPA 2134.

Graham

sure:

If you go to page 5 of the ST document (the first of three) you can get many pcb's, implementing different configuration. By the way, which configuration do you think is the best and how would you modify it for my goals (guitar mini amp)?

I buy something on eBay and other components on

Bye

It will a bit. A higher impedance than 100k is advisable for guitar pres. Say

220k min.

It's a strange world.

Graham

off batteries ?

Go to the computer shop, and get a pair of powered amplified computer speakers, and hack the plug to plug into your ax. They're so cheap, you could get another one for your bud, and since they're stereo, you could interleave the speakers.

Just parallel the stereo lines to a guitar plug, and off you go! :-)

Good Luck! Rich

run off batteries ?

Nah ! The input impedance is way too low. It'll wreck the sound. ;-)

Graham

Figures 15 and 16 on page 6 are relevant to your application ( single 12V supply ).

The application circuit possibly has a bit more voltage gain than you need but that can be determined when made.

Are you prepared to make your own pcb from the pattern given ? Keeping the power amp stage separate from pre-amp may actually be a sensible move too.

Ok. I see it has the TLC272 and even the OPA2134 ! And the right kind of pots. Excellent.

Graham

Yes, I often prepare my pcb by myself.

move too. Do you mean in the project you are designing ? I've done other project using 1/2 BC4558 o 1/2 RC4558 as buffer stages.

I visited the OPA2134 specs at:

In this document, alas, there are no pcb layouts like in the TDA2030 one. So, I think will need a differen circuitry as well if I use OPA2134.

Here is the 1976 Fairchild datasheet we have:

- (4 MB).

10706NB - No data on this part.

Regards

Try

5 gigs/mo for about $3. After abse use the excedent to get your fill of mp3s and nudie pics.

- YD.

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Remove HAT if replying by mail.

few

Thanks for the tip. That's the best price I've seen.

Graham