Hello everybody.

It's been a while since my last visit. I've been investigating about some tube preamps, since i've been wanting to have a multiple preamp with lots of modes and shinny lights.

But I'm also lookin for a poweramp to use my preamp. I've been considering lots of poweramps: Chips (TDA/LM), transistors (ála Randall), 5w Single Ended (AX84), 20w SE, 20w Push-pull, etc.

Today I was checkin' my bookmarks and found this site i visit a couple of months ago: http://milas.spb.ru/~kmg/index_en.html

He's an active member of freestompboxes, and has some pretty interesting stuff. Guy knows his biz. And they were two projects: a Fet Micro poweramp for recording (and or practice); and some Fet poweramps. And a Celestion V30 Simulator. Three projects, like I said.

I just wanna know if anyone at this forum is familiar with those projects, if someone has build 'em and have any opinion.

The Micro PA looks pretty interesting. Is a kind o' transistorized version of a Marshall PA, includes OT, V30 Speaker Sim and Speaker Saturation Simulator.


Here are the links:

Micro PA
http://milas.spb.ru/~kmg/microfetpa_en.html

Fet PA
http://milas.spb.ru/~kmg/fetpa_en.html

http://www.freestompboxes.org/viewtopic.php?f=2&t=9487
http://www.freestompboxes.org/viewtopic.php?f=13&t=8582

Hello everybody!

I wanted to share this with you. It's a simplifyed version of the pramp I'm desingning. It consists of multiple bypassable stages, switchable mods and it was designed using 3 Marshall Amps: 1959SLP (1 stage + pre-eq gain), JCM800 2203 (2 stages + pre-eq gain) and JCM900SL-X (3 stages + pre-eq gain). Each stage consists of a Noiseless biased SRPP using FETs

There are switchable mods: Bright cap, Boost (only for modes 2 and 3), Thick (for the 3 modes) and modable Tonestack (33k-470p/56k-220p/46k-690p).

I recommend you to use @15-18v

Here's the schematic:

http://i20.photobucket.com/albums/b228/Anti-Idiot/MPD-SingleVersion.jpg

EDIT: I forgot, please excuse me for not numbering each component, i'll do it ASAP. If you need to point something out, the reference is: 1st stage, 3rd stage, 2nd stage and pre-EQ stage. Also, the LED is a multicolored LED (R/G).

This is a single version. the other version should have 3 gains and 3 tonestacks with volume per channel (15 pots), output buffer, master volume, internal switching using relays (for bypassing stages and switching the gain/tonestacks), external channel switching (using this switching) and poweramp w/presence & resonance (this one). BTWm there's a mistake in the PA section, change the value of the 100u cap to 1u.


Please ask.

Hi everyone. I'm about to built a 3-channel SS amp. Since i want different EQ & gain controls for each channel, i wanted to know if there's a way of doing it without using  18 pots (vol, bass, mid, treble, gain & presence; x3). I thought about using LDRs, but that led me to use (again) 18 pots.

Another thing with the regular pots is, since i'd use relays to switch from one pot to another, the signal will be cut for a while (producing a big pop).

For what i want, i need some kind of digital potentiometers and some "memory device" (to save at least 3 presets). I don't need to save a gazillion of presets, only 3.

Pretty much like those new Marshall MG Series 4, they have a "simple" panel (and my amp is inspired by the beast of a billion pots, the JVM).



Please excuse my lame english

If I use this configuration

http://www.guitarraonline.com.ar/electronica/circuito1.gif

can i use an output transformer and make a NFB loop in a circuit like this?

http://www.runoffgroove.com/tc-tone.png

Hello everyone.
A few days ago, I was thinkin' about making some of the best emulators/simulators/adaptations of the classic ones. What I wanted to do is something like a JVM: 3 modes per channel. But, since 3 channels is enough for me (the JVM uses 4 channels, 3 modes per channel = 12 modes), my obsession led me to separate 3 groups for my project:

Channel 1 "Clean": Only Fender
A-Vibin' Champ
B-Professor Tweed
C-Bassboy 59

Channel 2 "Overdrive": Only Marshall
A-Plexizer
B-JCM800
C-???

Channel 3 "Distortion": Only Mesa/Boogie
A-Uno
B-Boogeyman
C-Dr. Boogey

As you can see (ok, ok, i'm a bit obssessive-compulsive, i know, please don't laugh) I needed a 3rd mode for the marshall, so i took the evolution of the jcm800, the JCM900 SL-X, which was an improved version of the JCM900 (without clipping diodes and with 1 aditional valve).

So here it is, another F4T project:



Q : MPF102 (all of 'em)

I took ROG's Phase Inverter/Poweramp thingy, since it's almost the same as in the 1959SLP, JCM800 and JCM900. I wanted (and so did Marshall) this to sound like a hot-rodded JCM800. However, if you need some original values for the P.I., here they are:

VR7= B25k
R17= 1k
R18= 15k
C22= 47n

Also, most of the preamp emulators uses a 10k instead of the 100k (of the source-follower?) and since everybody's doin' it, and i just wanted to be popular, i did the same, he he he (R4 and R13).

Miller Caps: C13, 14, 15, 16, 17, 18, 20 and 23 (try values between 100p and 220p)

I'll try to upload some clips when i finish the emulator (yes, i said it).

Thanx to all who inspired me: the guys at ROG & DIYStompboxes (Marty, Electrictabs, Mojotron)

BTW, this thing doesn't have a name yet, so if you have something clever, please let me know

i have:

Markfour X (since this model is based on the MkIV)
eXploder
X-tender
and a lot of crappy names...

Hi everyone. Well, here's the thing. I Have this small amp, a Marshall MG15CDR which i like. It has a unique sound (i used to have a MG15DFX, and couldn't stand its sound) but the "Line Out/CD In" jack is freakin' me out. When i plug a tuner, it works as Line Out. When i plug my Mp3, it's CD In. When I plug a cable to the PC it's Line Out, to the Laptop it's CD In. To another amp it's Line Out, but to a Cab-Simulator it's CD In. I can't stand that anymore. I don't care for the CD In, I never use it anyway, but i want the "Line Out/CD In" to be just "Line Out". Do I need to replace some resistors? anything?
Please, help me..

Teemu?

hi!
does anyone has the schematics for this 10w amp? the one with gain, volume and tone knobs and boost switch, or any guts shot so i can trace 'em? thanks!

Hi everyone!

i'm about to buy a Marshall G10 Mk-II (park) and i wanna know the differences between the G10 and the MG10CD. I have the schematics for the MG10, but couldn't find the G10 ones. Enzo doesn't have 'em, but i wonder if anyone know 'bout the g10, or have some pics of the circuit, or did some reverse-eng.
help?

Hi, i have this very odd schematic and i wanna know just 3 things. first, what the hell is this symbol?

L7


second, how much is the total resistance of the input, so i can calculate the total gain (just for the second op-amp)



i'm guessing, first, with the switch open, is:
Parallel R52 & R53,
Parallel R50 & R51, in series with R92
and both values in parallel, right?

third, wanna know the gain of the first and second amp (asuming pot is at max)




and final, any of you knows 'bout any good poweramp (just the IC), i think is called chip-amp, which can delivers 100 watts?

Hi. I'm new at this forum and just wanted to know your opinions bout the MG series. i have 2 MG15 (CDR and DFX) and i'm really glad with their sound. i dont like the digital FX on the MG15DFX, i just bought it for suck a low price, so i can open this little box and trace the schematic and do my own 4-channel preamp (and possibly a 100w SS-amp based on this ). so i have a few questions:

1. d'ya have any opinion 'bout this amp?

2. the preamp is powered by bipolar 16v, if i make a 100w poweramp, do i need to change the voltage of the preamp?

3. if i make just a rackmount preamp version of this (i really like its sound, but i need a more channels for a thrash sound) can i connect it to the FX Loop Return?

4. can i use any (like, ANY) 100w power amp? or do i need to change some stuff?

5. if any of you guys, have a 100w version of the MG series, can u check whats the voltage of yer preamp? (wanna know if the keep using 16v in the other models)

6. do ya have any info bout the speakers? i dont know 'bout using a 8-ohm cab or just one 8 ohm speaker. i mean, i need info of that (i dont know anything 'bout speakers)

7. if I trace the schematic of the preamp, poweramp and FDD (i wont trace the DFX or REverb thing) can i upload it here?

its nice to have a place like this (for SS amps) 'cos i personally think valves are overated and, since im kinda cheap and lazy, i dont wanna change valves every year, and i really love the MG sound (i've played a few SS amps and i hate 'em).

Thanx a lot, and excuse my bad english.