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Messages - Alexius II

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1
Amplifier Discussion / Re: My new amp (solid state "mesa recto")
« on: October 12, 2012, 03:48:35 PM »
Thanks  :tu:

The cost for the waterjet cutting was 8€ (around $10). Not a lot, considering one unique amp, but not really cheap if I would want to do similar things often ;)

The main problem was, this being a huge machine, the little letters would easily get flushed away as "debris" so we had to modify my drawing a little. Solution was to add a tiny line, few mm long and around half mm thick, that would not get cut - connecting the symbol to the rest of the plate. Worked like a charm, but some filing and sanding will be required. (just like some small model airplanes that have all the plastic pieces attached from the molding process)

el nino: since the "Mini Rectifier" already exists :-X I choose another name: Black Mesa.
This name tells us, that the amp was inspired by M/B - and that I am a serious computer geek (Half-Life anyone?)   :lmao:

Etching the name on a small plate (that was also cut from the same aluminium as other labels) will hopefully be the final task, thus concluding my work on this amp  ;)

2
Amplifier Discussion / Re: My new amp (solid state "mesa recto")
« on: October 12, 2012, 10:47:56 AM »
No comments.. I guess no one likes my design :tu:

Anyway, today I got the aluminium plate back:


And here is a quick ugly photo with raw unfiled labels placed on the amp:


It does look kind of strange to some people, but it turned exactly as I hoped.
I will continue on monday (filing, sanding, painting...) :)

EDIT: Also, all the visible screws have been changed to black hex type, as I like the look of them more.

3
Amplifier Discussion / Labels
« on: October 10, 2012, 05:51:39 PM »
Today I tried to do a few different label designs and came up with something like this:



Each sign represents a letter: I for input, G for gain, B for bass, M for mids, T for treble and P for presence, while maintaining the original sharp/linear theme from the logo. I am just now drawing theese in autocad, so that I can take them to a nearby workshop tomorrow (abrasive waterjet cutting). I have some 1mm and 2mm aluminum plates, so two different label types will be made: labels cut from 1mm aluminium plate, painted in black - and labels from 2mm aluminium plate with just the sides painted in black, like in the sketch above. If it turns out not to be what I immagined, the design will be changed. If all is ok, final pics should come soon  ;)

4
Amplifier Discussion / Re: My new amp (solid state "mesa recto")
« on: October 08, 2012, 02:10:11 AM »
Hello after quite a long time!

I now finally have some free time to finish my "almost finished" projects, and this is one of them. Some time ago I replaced those trimpots with fixed resistors and all the strange "noise artifacts" (scratching) are gone. I also replaced two bad pots and that ugly power switch (green led light instead of red/orange ac light). While doing that, I temporarely removed the buffer - and while testing the amp - found out it doesn't need one (for now). I might add a switched buffer at some point, as the line-out after tone stack without an buffer is not very nice.

I also have all the materials for the labels, which should be finished until the end of the week.
Will post photos and samples when it's done  :tu:

EDIT:
Did you use the Dr. Boogey circuit for your preamp?
Yes, the preamp is a Dr.Boogey. I made the PCB from gaussmarkov blog :tu:

5
The Newcomer's Forum / Re: Easy ss battery power amp?
« on: July 02, 2012, 02:55:15 AM »
Sorry, but 2N5458 and MPF102 preform quite differently in those ROG circuits.
The MPF102s that I got - they have twice the Vp and twice the Idss of my 2N5458s.

Even more different is the J201 with it's very low Idss and Vp.
And in most ROG circuits it sounds better than "replacements".

I strongly suggest finding all three (and I also like 2N5457) and testing them out.
You will find some sound better in one circuits, and some in other.

6
Schematics and Layouts / Re: Strange TDA2030 amp
« on: March 16, 2012, 05:54:22 AM »
Thanx for the offer, I realy appreciate it, but I don't think it's worth the effort :tu:

@Enzo: it's Epiphone EP10.

7
Schematics and Layouts / Re: Strange TDA2030 amp
« on: March 14, 2012, 05:47:14 PM »
Rechecked.
Good news: there is some kind of voltage divider in the preamp.. joining near the 1uF of pin 1.
Bad news: all things drawn are still there. I just don't get it :loco
(maybe this is why it realy souns like crap?)

There are obvious signs of "modifications" all over the pcb.. and a few components seem to be missing (a resistor, diode and a capacitor, all near the power section).

I give up. I will use the datasheet tda2030 layout/pcb, since I doubt the cheap internal speaker could even tell the difference.

8
Schematics and Layouts / Strange TDA2030 amp
« on: March 12, 2012, 04:26:20 PM »
Hi,

I've drawn this schematic from a pcb of the amp I'm trying to rebuild... but it seems very strange to me.
I've double checked everything, but I can't seem to understand how it works.

Do any of you see a mistake or something? xP


9
Preamps and Effects / Re: Preamp for Guitar Amp based on TDA2030A
« on: March 05, 2012, 07:21:35 AM »
Not a bad idea  :tu:
I could keep one original stage (fetzer valve) and add a different stage. Would there be any problems useing a stereo 1M pot for both volume controls?

Today I encountered another problem. It seems I somehow understood the transformer wiring wrong the first time :loco today I remeasured the transformer and under no load it seems to be at 26-0-26 VAC  :o

The only thing written on it is 40w, so I suspect it is around 24-0-24V (AC) under load.. which is quite a lot for tda2030. No wonder it was operating in single supply operation (around 35V DC, under no load). I guess I'll have to keep the power stage as it was.. since any voltage regulation will waste lots of power here :-\

Until next weekend, I will order most the parts.. and take some time to "read" the power amp schematic from the pcb.

10
Preamps and Effects / Re: Preamp for Guitar Amp based on TDA2030A
« on: March 03, 2012, 05:01:19 AM »
Great, thanks  :tu:  This makes it far simpler.
...but, could switching (disconnecting) the unused stage have any benefits?

11
Preamps and Effects / Re: Preamp for Guitar Amp based on TDA2030A
« on: March 01, 2012, 02:54:05 PM »
I too have lots of other stuff on my mind (getting my degree in civil engineering soon) so this project will be limited to Saturday afternoons, when I'm home  ;)

I actually did use Thor as preamp before... here is a photo: http://www.box.com/s/vay73gx0e3v3lul14nla
It has a marshall tonestack + presence control (same filter as a mesa dual rectifier). The rotary switch changes treble caps. The two outputs are preamp out (buffered) and speaker out (there is a small LM386 amp inside). It sounds good with a good power amp and pretty poor with the internal 386 (this chip just eats all the treble out of the tone)

As far as the power amp goes, I will re-do it using the Valvestate 8010 schematic. The original was wired for "single power supply" which I find strange, since the transformer can do 18-0-18 (dc).

There is only one thing I'm not sure about. The amp (EP10) has two inputs. I would like to use both; the first as the "low hain" and second as "high gain". Each would have it's "own first jfet stage" (a fetzer valve) using a MPF102 or 2N5458 for low gain and 2N5457 for high gain. Voltage gain of the first input would be between 1 and 2, and for the second between 5 and 6. Do you see any problem with wiring both jfet stages' outputs together? Let me draw my idea: http://www.box.com/s/gcytboz847x5vqksdtly
You can see the original circuit here.

I can wire the input jacks in a way that plugging into one - shorts the input of the other to ground... and vice versa. Would this be ok, or have I missed something? Is it necessary to disconnect the output of unused jfet (using some sort of a switch)?

12
Preamps and Effects / Re: Preamp for Guitar Amp based on TDA2030A
« on: February 26, 2012, 05:34:21 AM »
Hi,

just yesterday a friend brought me a beaten up amp - Epiphone EP10 which sounds horrible. It has half of the pots/jacks broken or damaged. He just told me: make it sound good... so I decided to replace the whole preamp, while keeping the same power chip - TDA2030. Since I'll be doing basically the same thing as you, I can post some photos of my progress if you want  :tu:

The "preamp" I've chosen is the Thor circuit from runoffgroove, as my friend mostly plays overdriven rock stuff... and there will be a classic marshall tone stack after.

Amp's current state is this: (I just pulled the guts out :cheesy:)
http://www.box.com/s/p7apqth18clq7doxqnpg

13
Tubes and Hybrids / Re: Hybrid project started.
« on: February 18, 2012, 08:14:47 AM »
Yeah, I'm a metal-head, but this is way too dirty even for me  :duh

The amp does however sound quite good when using a distorted preamp and driving the output tube just a bit over the clean area. Nice compression and gritty character. This is how I use it most of the time, and the great thing is - it does this at bedroom level, as it produces only 1 or 2 watts  8)

I will be making another similar amp with the full tonestack, as it really has a BIG effect on how nice/bad the output tube sounds when overdriven.

14
Tubes and Hybrids / Re: Hybrid project started.
« on: February 17, 2012, 12:47:04 PM »
I recently made a small self-split push-pull tube amp using not the 12au7 but quite similar russian 6N1P (dual triode). It is very similar to the G2 kit from madamp and sounds quite nice (clean to crunch). I stumbled upon this thread and decided to post a short recording of severely distorted output... maybe it will help someone decide to (not?) build this thing :lmao:
Most will find this type of sound disgusting, so be advised :duh

Guitar signal was boosted with ROG Thor.
http://www.box.com/s/ik3s6erp5otdufbr5jjh

15
Schematics and Layouts / Re: TDA2003 Suggestions
« on: November 28, 2011, 05:51:41 PM »
It seems my lm386 builds might actually be louder. Both are equally clean I'd say.
Maybe you set your LM to have more gain than the TDA, or maybe the early clipping of the LM is percieved to be louder. I've A/B tested them, and TDA was about twice as loud, which is not surprising as it had about 10 times the output power (LM386@12v into 8ohm and TDA2003@18V into 4ohm). I used overdrive/distortion preamp as it was hard for me to determine the loudness of cleaner sounds.

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