Chime Amp (Punch Amp v.2)

[Heath]

(I have built this from the layout posted below and it works wonderfully, so it's verified as far as that goes)

http://www.youtube.com/watch?v=S5ZGNhxKEyg



While I like the Noisy Cricket, I wasn't getting as much volume as I wanted, and definitely not enough clean volume before distorting.

Chromespherecom @ diyguitarpedals.com.au came up with the Chime Amp which sounds amazing and has lots of clean output.  

A neat feature, if I understand correctly, is that this IC recognizes the difference between an amp speaker load and a headphone load and should operate accordingly.


**** NOTE ****
 This is the first time I've ever even attempted to create a vero layout from a schematic, so if there's something stupid I've done there, so easy.  I realize it's a very small and simple schematic, but I'm mostly retarded, so it's a big deal to me.

Vero:



Schematic:

[Freppo]

Thanks Heath for bringing this circuit to my attention
Exactly what I was looking for! Good job on the vero :)

I redrew your layout for my own use, so I could fit it inside a supertiny enclose.


edit: Forgot to say that it's verified and sounds pretty good.
It doesn't get loud (i'm using it with a 8ohm speaker), but it's clean all the way.

cheers
/ Freppo

[Heath]

That's fantastic, man!

I've saved your version for my own use as well.  I'm so glad you found it useful.  It's a great little amp.  I've thought about putting this circuit in a little cigar box amp with a little 4ohm speaker along with a SHO or something to throw some dirt on it when desired.
     

[Muadzin]

Question: Does this amp handle pedals well? As in dirt pedals?

[Heath]

I've been doing some moving around so my unboxed circuits are in a box (no pun intended) underneath some other boxes.   Next chance I get I'll try a few out dirt pedals out with it and let you know.  

[dexxyy]

Muadzin wrote

Question: Does this amp handle pedals well? As in dirt pedals?

In a word  no. I`ve tried a few in front of it and it motorboats like hell, even a booster makes it motorboat. Makes a great little headphone amp tho`.

[dexxyy]

Ok played about with this again and it WILL play with dirt pedals BUT it will motorboat if you try to exceed it`s max volume, so you need to turn the volume of the amp down as you increase the gain or volume of the dirt pedal.

[Freppo]

Too bad to hear about the motorboating.. :/
I never tried mine with a dirt-pedal.

Here's in mine :P


/ Freppo

[piltdownman]

That is gorgeous!

[Heath]

Freppo!  That looks badass!

[Freppo]

Thanks guys! :)

I just thought I'd mention that I've been using my Punch amp for late night playing, and I have no problem blasting distortion-boxes or boosters with it. My only gripe is that the volume drops alot when the battery is draining.

/ Freppo

[Kinski]

Just built this. Sounds MUCH better than the 386 amps I've made. Much louder and cleaner.

Swapping the 100k volume for a 1M made it much louder. With the volume all the way up, it just barely starts to distort with humbuckers, and the clipping is not too bad either. This is with a OneSpot at about 9.4v. With a 9v battery (reads 8.4v) its noticeably quieter and more distorted, which I guess it to be expected. Seems more sensitive to voltage than the 386 amps, but not a too big of a deal.

Should also mention, it does not seem to like a boosted input signal. I find if any pedals running into the amp are set far above unity, the IC gets pretty hot. Other wise, it handles any and all pedals I've thrown at it quite well. Fuzz sounds great. As does reverb, delay, etc.

Thanks for the layout, Freppo!

[Kinski]

where would be a good place to add a simple tone control to this?

[Neil mcNasty]

Regarding the issue about motor-boating (I've experienced this myself):
Are you getting this when using it with a power-supply, or only when running on battery power?

The reason I ask is that; lately it struck me that a single 9v battery probably does not have enough milliamps to run a 1 Watt amp at max (and then some...).
And therefore; when the current draw exceeds what the battery can deliver, it results in a lowering of the voltage supplied to the amp, which in itself makes the amp circuit more prone to oscillation and misbehaviour, since this is something that often happens when the battery is low in small amps like these (my experience)

What I suspect is that: when pushing the input of the JFet buffer front-end, the current draw increase quite a bit, exceeding the capabilities of a standard 9v battery.
As far as I understand the JFet transistors: the voltage at Gate has an effect on the (amount of) current-flow to the Drain, and therefore a strong signal at Gate will increase the current consumption (resulting in sag/lower voltage from the battery), and therefore there is no motor-boating/oscillation when lowering the input signal/voltage.
Remember that the IC is doing the amplification involved here, and that it all-ready consumes a fair share of the milliamp capability of the 9v battery. AND: if this current surge happens in the JFet as a result of high gate voltage, it could drain the battery to hard and then also bringing everything down in voltage.

from what I've experienced, it only happens when pushing the input on battery power.
So I guess that it has to be an issue linked to the signal strength/voltage at the Gate of the JFet
Is this correct logic?
Could we be under-estimating our power supply capability, compared to what we are trying to achieve?

Though I have to admit that I do not have any clue about what I am talking about here...
This is just the way my logic works on this subject, based on my limited knowledge...
Great if someone can correct me if I'm way out there! Love corrections!

(If I'm on to something though...), my conclusion will be that: in order to solve the problem, we have to increase the performance of the battery in use (increase milliamp capability), either by running several 9v batteries in parallel, or by using a "stronger" 9v battery.

It would not surprise me that these amps are capable of high power consumption, because you can get a hell of a lot of volume and rage out them, if you push them really hard.
They are great recording amps and they sound HUGE in the mix!
I've had my brother's kids coming into the room holding their ears, complaining about loud volume from an amp like this. That's pretty cool... And that demands POWER!!!

Rock On!

[Kinski]

Wow, thanks Neil for your thoughts!

It only oscillates when using a battery. I ran two 9v batteries together and it still oscillated.

I didnt think the milliamps would be much of an issue, as I asumed the Woodrow, being an electra, would not require much. In fact, thats one of the main reasons I chose and electra based circuit. It cant pull more than a few milliamps, no?

Also, the amp only oscillates when the Woodrow is engaged. But the woodrow is still being powered even when not engaged, so it if the milliamps were the issue, the amp would oscillate wether the Woodrow was engaged or not, no?

[Kinski]

Anyway, I just ended up building some ruby amps instead for gifts and they sound just fine.