Schematic of my lil rock amp

[Colas LeGrippa]

Here s the schem. of my lil' rock amp that I play in the sound clips section of this forum.  ( see smoke on the water, allright now, black magic woman )I designed it over the years  with your help. I couldn t do more with only two volumes and a switch. The speaker is a Jensen alnico 8 in, coupling capacitors Jensen paper in oil and orange drops polypropylen. The trannies were found in a box in my garage....

[Colas LeGrippa]

VOLTAGES


V1 1  :  204 V
V1 6 :  310 V


V2 1: 220 V
V2  6: 370V


V3 3 :  415V
V3 4 : 412 V
V3 8 : 28 V


Power: 


382 ohm :   75mA @ 380 V = 28.5 W
483 ohm:    62 mA @ 388V = 24 W

[Colas LeGrippa]

The K switch is always to the hot side , 28.5W, which is too hot for a 6CA7 but better tone.


Colas

[Colas LeGrippa]

There is a 1 OHM 5W iresistor in series with the power tube K resistors . I forgot to draw it.
The power tranny no. is: NSC125P1B.
The OT brand is unknown. It measures 4k primary.
The choke is 3.5 H.

[SILVERGUN]

Here s the schem.

No wonder why that thing sings.
Very nice drawing. I might just have to build one for myself. We need a name. Maybe "The LeGrippa Ripper"?
Nice work and thanks for sharing!

-You've got a 1K (in series with the other 1K ) to the left of the 50uf cap that feeds the screen. Did you mean to have it on the right side?
-The bottom 100uf cap says polarity next to it and seems to be drawn with the + and - signs reversed.

[Colas LeGrippa]

Thanks for nice comments.The two 100uF in series are connected + - - +.
The drawing is bad cause the curved line of the second one should be on the other side.


The 50uF is hooked up the way it is drawn thougjh it could be placed between the two 1K.
The second 1 k was to lower the screen B+ supply under the plate voltage.


A name ?   Gee I ll have to think about it.


One thing: the OT supply is meant to be connected AFTER the choke. My experience in building SE amps showed me that they are a bit touchy with oscillation and to avoid issues of that type, we must insert the Pi filter before everything.

[Colas LeGrippa]

For more tone control, a tone pot can be connected to the master volume pot. I keep the hi/lo switch to lo!, since the humbuckers on my 61 Jaguar ( some people think it s a sin ....)
are too much powerful. As a matter of fact I would have hooked up a tone pot ,  with more room inside the chassis.
The reverb you can hear in the clips come from an outside reverb unit connected to the 16R tap and amplified wirh a second high gain amp. Thanks to Sluckey for that trick.

[Colas LeGrippa]

LINDA my naked neighbour is haunting me.
The only way I can forget her is play my guitar.
Good night.

[SILVERGUN]

I think you just came up with the name. There was a famous American amp builder who used to name his amps after women.
We need to know more about LINDA:
-Is she a bit of a trainwreck?
-Does she sing?
-Is she bi-polar? (like that cap configuration you got there +--+)    I have never seen that and it very well might be a ticking time bomb
-Does she practice black magic?
-Has she ever smoked on the water?
-Is she all right now?
 

[Colas LeGrippa]

Ticking time bomb ?? No.
It is how we turn polarized caps into non polarized. Mojo trick. ( but dont tell nobody ).


Note there is no bleeding resistor. If you build one, remember to bleed the caps. More than one time I got "shocked"  by this particular amp.


Forget about Linda. I suggest Lil' Gripper.

[sluckey]

I thought this was settled long ago. ICATT

[SILVERGUN]

Ticking time bomb ?? No.
It is how we turn polarized caps into non polarized. Mojo trick. ( but dont tell nobody ).

Thanks for the explanation, that's a new one for me. Still not sure how that is useful, but it sounds good so it must be good.

Well, I found a good donor in an unfinished EL34 SE amp I "designed" that didn't turn out well, so this might happen sooner than later. I've already got 410VDC plates, so I'm halfway home.

I'll go with the Lil' Gripper + TMB with the ICATT, No Mojo Mod, with Bleeder Resistor or just the LG+TMBICATTNMMBR, so as not to marginalize anyone's feelings.

[Colas LeGrippa]

ICATT understand  your  letters game.


No, Sluckey, it s not over. I have been traumatized when hit in my face by a pair of 45's.


Silvergun, you seem to be scared by the reversed polarity This is where all the "magic" of the lil' gripper stays.
I needed all the power available from the PT. That is why I did not put any bleedimg resistor, though 1 meg  wouldn't suck that much power.

[kagliostro]

It seems your schematic deserves to be seen at the  best



Ciao

Franco

[SILVERGUN]

It seems your schematic deserves to be seen at the  best

Gracias, Franco!...It is a nice little work of art

Silvergun, you seem to be scared by the reversed polarity This is where all the "magic" of the lil' gripper stays.

Not scared. I just don't believe in magic  .
I did find this thread that I'll read through later to try to grasp the concept of how/why this might be useful.
Can you make a non-polar electrolytic capacitor out of two regular electrolytic capacitors? - Electrical Engineering Stack Exchange

[sluckey]

It is how we turn polarized caps into non polarized. Mojo trick. ( but dont tell nobody ).

Lot's of us know how to make a non-polarized cap from polarized caps. Why do you believe there is any benefit in doing this for a B+ filter cap?

[Colas LeGrippa]

I  know it is not a secret señor Sluckey.
It is everywhere on the net. Only Silvergun didn't know that


I had once built a very nice sounding amp with all non polarized caps, I just wanted to try it once again in this amp but I didn't have in stock all the caps needed to do the reservoir, screen and preamp.
Any benefit ?  I would have to perform more tests , with a scope to certify it. One thing is sure: it works as well !!!!


Silvergun, you should believe in magic , there lays all the happiness (  a warm gun....heyhey )

[SILVERGUN]

For more tone control, a tone pot can be connected to the master volume pot. I keep the hi/lo switch to lo!, since the humbuckers on my 61 Jaguar ( some people think it s a sin ....)
are too much powerful. As a matter of fact I would have hooked up a tone pot ,  with more room inside the chassis.
The reverb you can hear in the clips come from an outside reverb unit connected to the 16R tap and amplified wirh a second high gain amp. Thanks to Sluckey for that trick.

Don't think I missed this. I will be including the 2:1 V divider on my input. And a tone control.

I'm also thinking about splitting the output so that one speaker out goes direct to a speaker cab to have some control over the reverb mix.
Do you disconnect your 8" speaker when you hook up the reverb tank?

[Colas LeGrippa]

I leave the speaker connected. This is my dry signal.
I connect the input of the reverb tank to one of the remaining speaker out of the main amp ( lil gripper , hey hey I like that name ) and the output of the reverb goes into another amplifier. But read your reverb tank specs, you ll have to put a resistor in series with the tip of the input in order to protect the reverb input coil.

[Colas LeGrippa]

....so the dry and wet signals come fron two separate speaker cabs, which gives the tone a dimension much more interesting than if both signals would come out from the same amp (or a unique speaker cab ).

[DummyLoad]

lil gripper , hey hey I like that name

a masturbating midget or an amp?

--pete

[Colas LeGrippa]

Masturbating ??????


It ain't no push pull but SE