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Messages - blackcorvo

#61
Amplifier Discussion / Re: Black Box Amp
August 17, 2015, 06:31:04 AM
If I wanted all the power I can squeeze out of this amp without losing the portability, I could easily put together a "15v" pack out of 4x 18650-type batteries for it. A 16v laptop power supply could be used to charge it to full capacity.
#62
Amplifier Discussion / Black Box Amp
August 16, 2015, 10:24:27 PM
Recently I got a bunch of TBA820 ICs, and I thought about putting one of them to use in a mini amp project.

By their own they're not that great, but after putting a small preamp in front of it (borrowed from this post by PRR on diystompboxes), they actually sound pretty decent, specially through a proper guitar speaker.

Here's the layout I'm using and the schematic, plus a couple photos of the final build (I used a dual pot for the treble+bass control due to space limitation):




It does overdrive a little, but nothing too exciting. The LM family of chips sound much better overdriven IMO. It's more of a clean amp to be used for practice with pedals or as a bench test amp.
#63
Preamps and Effects / Re: Monarchy Drive
August 16, 2015, 01:33:24 PM
Quote from: J M Fahey on August 16, 2015, 11:52:05 AM
1) sorry, Dropbox FORCES you to become a member and sign in, I suggest you attach that same .PDF here so anybody can see it.
Reply to the post, ckick below "Attachments and other options" and upload straight to SSGuitar .
2) o senhor é Brasileiro?  kkkkkkkkkkkkkkkk ;)

Fixed the file situation, now it's attached to the post.

Sim, sou brasileiro!
#64
Preamps and Effects / Re: Monarchy Drive
August 15, 2015, 10:34:45 PM
Quote from: J M Fahey on August 14, 2015, 03:42:23 PM
Em Pee Threes !!!!!!
Em Pee Threes !!!!!!
Em Pee Threes !!!!!!
Em Pee Threes !!!!!!
Em Pee Threes !!!!!!    :trouble

Tomorrow I'll have something up. For now, I have a very neatly made layout produced by my good friend Plautz from the Handmades.com.br forum, where I also posted about this circuit. Enjoy!

(File is attached to this post)

[EDIT]

Thanks J M for letting me know of the dropbox sign-up thing. I wasn't aware of that.
I also would like to add something I only noticed today: the bypass cap in the PDF is marked as 10uF when I actually used 2,2uF. It's the one right next to the transistor in the layout.
#65
Preamps and Effects / Monarchy Drive
August 14, 2015, 01:51:11 AM
I stumbled upon this circuit the other day, and since Vox amps always had one of my favourite types of tone of all time, I decided to try his circuit.
But, to be honest, the sound didn't cut it for me. The Headroom control was specially not that great to my ears. Sounded too much like crossover distortion when not at it's minimum setting, which I am not a big fan of.

So, I experimented for a while and I ended up with this:



It has a much more dynamic (i.e. gradual) distortion, a little more gain and compression, and a much closer sound to what Vox amps sound like (to my ears).

The idea is that, by cascading the clipping circuit using diodes of different voltage drops, you can simulate the gradual, cumulative type of distortion that happens on a tube amp. Each clipping stage simulates a different stage on the amp (the bicolor RG LED would be the preamp, the 4x 1N4148 are the phase inverter, and finally the BAT43+1N4148 is the power amp).

Plus, you get a cool "clipping" indicator with that bicolor LED.
#66
Quote from: mguzzo on August 10, 2015, 04:23:31 PM
i haven't chanced opening my PF10 yet to do the LED mod. I'll try your method first.

It's a good way to try it out and see if you like it, without fear of damaging the board.
It's not gonna be permanent of course (unless you, like, glue the spacer pieces in place or something like that, which I wouldn't really recommend).
#67
You could flip that thing upside-down and build a metal chassis on the "bottom", screwed to the sides. Then just use two wooden planks for the front and back and voilá!
Simply drill a hole in the midde of the bottom (now your top) piece to run the wires for the speakers. That way you can have a better closed area for the speakers.

Like this (quickly done in paint, sorry!) :


Attached it just in case tumblr decides to delete the image.
#68
If you want high capacity and portability, I'd go with some 3.7v "tactical flashlight" batteries.  3 of those in series give you 11.1v, and if you get the 5600mAH models, I'm guessing they'll last you over 10hrs of play time with any chip power amp up to like 5w.
#69
Quote from: MCM1910 on June 08, 2015, 11:19:58 AM
Thanks for posting this.  Are the recent Honeytones made with surface mount components?

Yes, save from the electrolytic capacitors and the power amp I.C. everything is SMD.
#70
So, the other day I decided to open up my lovely Honeytone amp to do a couple mods. Added a speaker out jack and a rechargable battery pack to it.

In the middle of it, I noticed the resistors for the second op-amp had different values from the schematics I've seen online (1k/2k2 instead of 2x 33k), so I decided to correct that.
Before doing so, I looked up other sources to confirm the values were up-to-date and I had my confirmation here http://batterypoweredguitaramp.com/danelectro-honeytone-guitar-amplifier/.
But instead of just correcting the already drawn schematic, I said screw it and just drew the whole thing again.
I ommited the LED and On/Off switch for simplicity, as this is only a reference circuit.

Here's the schematic:


I'll be attaching the picture as well, just in case the source links for it get lost in time.

And in case anybody is curious about the mods, I have made a post on my tumblr about it
http://blackcorvo.tumblr.com/post/120898269985

And also a quick demo video of the finished product through a 10" speaker
https://www.youtube.com/watch?v=7KAEKuLByUc

I like this amp's circuit enough that I'm seriously considering cloning it, but using a TDA7240 for the power amp. Maybe when I get the materials for producing PCBs? We'll see.
#71
So, I bought a Vox Pathfinder 10 this week in pretty good shape. Looks brand new, came in the original box and everything. Then I tried playing with it...

With the switch on clean it sounded nice, but once I tried using the drive it sounded really crappy. It also had a bad treble pot (it scratched and cut out the sound between zero and 1/2 way on the knob). So, I opened it to see what I could do about the pot.

Surprise surprise, someone modded it putting two diodes in place of the LEDs (ge and si), and did a very crappy job too. The pads in the pcb for the LEDs were pretty much history. I think only one diode was actually in contact with the copper and that explained the crappy drive sound.
Thankfully I was able to restore it to have the original red LEDs in there and it sounds much better now! Then I put a 100k pot replacing the bad 50k (that's what I had available). Really digging it now!!!

But after all that, I remembered the oh so famous LED mod some people do, where you would remove the LEDs from the circuit to get a more "natural" sound. I discovered you can achieve that without having to open the amp!

Simply slide a piece of plastic or metal in the space between the drive switch knob and the hole in the chassis so it stays in place when you move it (before it clicks). Slowly push it until you find the sweet spot where the LEDs are not switched in but the boost is active. Boom, LED mod without even touching a screwdriver!
#72
Tubes and Hybrids / Re: Meet the PushOver
November 10, 2014, 10:35:10 AM
Quote from: Roly on November 10, 2014, 08:55:59 AM
Now there is a man who understands the meaning of "compromise".   :lmao:
{If you only get yourself one thing for Xmas, make it a step-drill - when it comes to larger holes you'll  <3) it.}

Excellent improvisation  :dbtu:, but I'm curious, I feel I should recognise whatever that is that you used for a chassis even after you beat the living crap out of it, but I don't.  ???

If I haven't mentioned before, computer repair shops will generally give you all the dead power supplies you can carry, and apart from the wire and sundry bits, the cases themselves can be used, even bolted together, as tough project cases, e.g.;

I would love to get a stepper bit if they weren't 200 bucks a pop here in Brazil (at least I couldn't find any cheaper than that). Also they're very hard to find! I don't even think there's a single store that sells them in my town.

The chassis is made out of leftover gutters my dad found in the street. Just very thin (0,5mm?) aluminium, easy to work with.

I know about the whole computer PSU deal. We had bunchs of those cases lying around, but I have no idea where dad stored them, or if he got rid of them.
#74
Tubes and Hybrids / Re: Meet the PushOver
November 02, 2014, 08:39:15 AM
Yes, I started experimenting with voltage multipliers after reading about those builds from ozvalveamps. However I prefer using only one P.T., because if I were to use more than one like they do, it would be the same price as just buying a transformer with B+ windings. They're not that cheap here in Brazil.