PUNCH - 1W amplifier

[garcho]

Sorry, I didn't read your post closely enough and honestly, I had a few beers... 

Was just thinking that pushing tubes sounds good, that's all, but now I realize I was thinking about something else. Maybe pre > TS > tube > power? IIRC Rick at Frequency Central has a lot of 12au7 projects around here and other diy forums, too, might be worth digging around.

Still love op amps, even sober, ha!

[DefiantAudio]

I like a lot of Frequency Centrals low power tube amps. I'm just trying to avoid using anything high voltage related (like how a lot of FC's amps use a charge pump) which is why I thought this punch amp would make for a nice amp/head. I'm going for something along the lines of a small Marshall Valvestate (hybrid valve pre/ss power) amp, but still powered with 9 or 12V.
Another idea I had was building a Dr Boogie (or similar) before the Punch and rocking a small knock off SS Mesa/Boogie style amp.
I think I'm just going to end up going to the dark side and rigging up a charge pump. I've seen a couple spiffy 12au7 push/pull amps I may take a crack at. But I still intend to make a ValvePunch in the mean time. I'm just waiting on the chips and a few other components to arrive. Buying stuff on Ebay and having it shipped from China to the US takes forever ha. The joys of buying cheap/bulk items I suppose.

[DefiantAudio]

Just got my chips! Looking through here, it is said to not ground the output? I plan on using a 1/4 jack, so do I run the signal from pins 5 and 8 (?) to the jacks tip and sleeve lugs? Or do I ground the out entirely differently?
Sorry for the possibly ignorant question.

[chromesphere]

Hi Defiant, not sure I totally understand your question but the negative of the speaker output is not the same as the ground of the enclosure.  It should be left isolated from the circuit/enclosure ground.
Hope that helps
Paul

[DefiantAudio]

@Chromesphere Sorry for the unclear question and thanks for the attempt at an answer hah. You could be a champ and do a youtube video of step by step assembling your 'chime' amp and you would be my hero   haha
Ahh how to reword it...?
According to the layout/schematics throughout this thread (TCA's schem/pcb on the first page or chptunes schem on page 4), the chip has 2 outputs ( pins 5 and 8 ). What do I do with those outs? Both to tip of the speaker jack or...?
And part 2 of my question about the grounding the output:
How/where would I ground the output without connecting it to the circuit or enclosure? Run a wire from ring to ring of the jacks? Or the ground from the 9v?
Basically I'm asking how to entirely wire the output section of this thing. The isolated ground and 2 outputs has me confused.
I'm sorry if this still makes no sense. I really want to build one of these and like I've said before I'm still very new to the DIY scene. Any help and patience is greatly appreciated.
Thanks
-Mike

[chromesphere]

Ah I see.  Ok well its a little difficult to explain but ill give it a crack.  I used a plastic sleeve jack for the output so that the jack WOULDNT connect either of the speaker outputs to the ground of the enclosure.  You don't want to do that, neither pin 5 or 8 (+ / - outputs) should touch circuit / enclosure ground.  Most metal sleeve jacks will connect the sleeve to the enclosure which no good for a speaker output so be careful of that.

To work out which + and - goes to which part of the jack you will have to follow the signal through the cable into the speaker, I'm not sure off hand if there is a 'standard' wiring for this.  Just use your multimeter to check it and follow it along. 

+ and - (pin 5/8) need to go to plus and minus on your speaker.  To understand how to wire up the output correctly you may want to just omit a cable & jacks initially and either pretend to or actually wire up the output directly to the speaker and then add the cable then the jacks.  Your multimeter should be able to help you work out the wiring though pretty simply. 

[PRR]

> the chip has 2 outputs

And the speaker itself has _two_ input terminals.

On breadboard, just wire the two chip outputs to the two speaker inputs.

Problem comes ONLY because it is traditional to use a 1/4" plug for speakers. Normally the shell of a 1/4" plug (and its jack) go to "ground". On this chip *neither* wire may be grounded. So the 1/4" jack must be mounted UN-grounded. With the all-metal SwitchCraft jack, this needs insulating bushings (or an insulating panel). On the mostly plastic jacks, you just wire tip and sleeve but do NOT connect sleeve to ground.

The shell of the 1/4" plug ends up "live". This is poor practice. It is not dangerous because there is only a few volts, at most, on the shell. If grounded through a human you won't get enough current through skin (even wet) to be shocking. If grounded through metal, the chip will shut-down so no harm is done.

[DefiantAudio]

Thanks for the replies. They are very helpful. For the sake of not harming the speakers (if that is an issue?) any idea if I can test this out on a small radioshack speaker before trying it out on 2x12 speakers in a marshall combo? What I mean is theoretically if it produces sound through the radioshack speaker, it should theoretically produce sound through the 2x12's right? Or is speaker wiring not a standardized thing? And out of curiosity, would this chip power a 4x12 speaker cab or would there be modification to the circuit to make it work?
Oh yeah. Last (hopefully) random question: Will it make much of a difference using ceramic caps instead of film in this? I have loads more ceramics than films.
I plan on putting this amp together in the next few days (as soon as I have time).
I'm sorry for the constant questions, but you guys are really very helpful. Im trying to cover all my bases before building in the hopes of cutting down on the debugging after its built.
Thanks
-Mike

[tca]

Thanks for the replies. They are very helpful. For the sake of not harming the speakers (if that is an issue?) any idea if I can test this out on a small radioshack speaker before trying it out on 2x12 speakers in a marshall combo? What I mean is theoretically if it produces sound through the radioshack speaker, it should theoretically produce sound through the 2x12's right? Or is speaker wiring not a standardized thing? And out of curiosity, would this chip power a 4x12 speaker cab or would there be modification to the circuit to make it work?
Oh yeah. Last (hopefully) random question: Will it make much of a difference using ceramic caps instead of film in this? I have loads more ceramics than films.
I plan on putting this amp together in the next few days (as soon as I have time).
I'm sorry for the constant questions, but you guys are really very helpful. Im trying to cover all my bases before building in the hopes of cutting down on the debugging after its built.
Thanks
-Mike

I don't think you can damage that kind of cheese speakers with a 9V battery amplifier (check this for a preview: https://www.youtube.com/watch?v=TPckPDHDAMM)

Use any kind of caps, no difference.

Cheers.

[ncidurhed]

The first time I was on this site I found a schematic for a punch amp + distortion. The original design was by Tiago Charters de Azevedo and it was modified by nomorebetts. If anyone can help me locate that or point me in the direction of a similar one it would be greatly appreciated.

[tca]

^ Here: http://www.diystompboxes.com/smfforum/index.php?topic=105106.0

Happy hacking!

[tca]

I've received some PM asking a replacement for the MPF102. The JFET is only acting as a buffer, any other JFET will work. Or any other type of buffer also, e.g., with an op-amp.

Cheers.

[FuzzBobTransistorPants]

hey would it work if I use an 8 ohm speaker and like a 70 ohm resistor before it? I have a bunch of 8 and 4 ohm speakers but not a single 80 ohm, so wouldn't it be the same if I used a 70 ohm resistor and an 8 ohm speaker in serie instead of an 80 0hm speaker???
kind of new here ha ha

[FuzzBobTransistorPants]

ok its me again, what would you say the maximum consumption in mA would be? 200? 300? 400? 500? I have a few different adapters I could use and they are 9v

[Luke51411]

It wants an 8 or 4 ohm speaker. If you see 80 ohm it's probably a typo.

[shrike88]

Hey Guys,

Just a question regarding volume that maybe you can help out with. I built the punch amp as per chptunes schematic (on page 3 of this thread) and I find the volume is quite quiet. I would say it comes out at conversation level. I was hoping to get it a little bit louder if possible. I have it being run with a 11.5V 1.95A power adapter.

Thanks

[chromesphere]

Might be your speaker size Shrike?  Mine is so loud in front of my fender amp (2 x 12) its uncomfortable

[shrike88]

I'm using an old Peavey Solo amp chassis & speaker (like this -> http://medias.audiofanzine.com/images/normal/peavey-solo-241585.jpg) to run the amp through. With the original electronics this thing was quite loud. Unfortunately a power surge fried most of the innards on the original.

Also, you make some pretty awesome youtube vids chromesphere

[chromesphere]

Thank you sir!

Difficult to tell what size that speaker is from the photo, 8 inch maybe?  Pretty sure the 6 inch speaker I tested my punch amp was pretty decent in volume.  Its only 1 watt so don't expect to blow your windows out but still should be ok for practice.  Maybe check over your circuit for errors or try it on a larger speaker if you have one around. 

[shrike88]

It's an 8" speaker. The original was 15 watts (with dual RC4558 ICs) so maybe this all I can expect.