50w highgain mod

[M Fowler]

gldtp99,

Sounds like some kool amps and circuits your working on and planing on.

I was wondering how the Marshall 2550 is? Looking at Ceriatone's layout and chassis photos it would be a fire breathing monster, which equals fun!

Mark

[gldtp99]

From re-tubing/servicing my friend's two Marshall Jub heads (2550's) recently--- i think that the Splawn-based circuit has easily more gain available. Especially in Gear 3 mode (good for a lead boost IMO--too much for chording----at least that's my feeling right now- )
I've also listened to all the hi-gain amps on James Lugo's shootout vid series and i wasn't impressed by the ones that use diode clipping (that i know of)--- the real Jose, the Friedman (Marsha)---i liked the Wizard and the Cameron CCV better--- i mean, ALL those amps sound good but some hit my ear better than others--- it might be different if i was able to play all these amps live, in person.
Maybe i just like the idea of using tubes to generate these tones instead of solid state devices---but on the other hand i'll grab my Keeley-modded Tubescreamer to see how well it might boost a hi-gain amp.
Do you have the Chupacabra schematic ? Or are you going to buy a kit from Nik? I read somewhere that this amp is supposed to be similar to the Friedman schematic floating around-----and that they're both based on an amp built by Jose long ago.
So right now i'm going with a plate-driven tonestack, etc (Splawn-type)--- it will save space when building the true dual channel switching amps i'm planning on---i've got most of the iron for four 100---150 watt heads now.
That's my thinking, at the moment--- but this is subject to change at any time--- .......................gldtp99

[M Fowler]

The chassis is available from Nik but no kit for the Chup.

I received a QR schematic email me for it. I did see it posted on a few sites.

I like what I hear in the Splawn Nitro and QR so I want to build the QR since I have that schematic. The Laney Ti-100 looks like it would be good Marshall variant as well. And without diode clipping.

[gldtp99]

I already have the QR schematic--- here's a pic of the 50 watt QR-based amp i built (lead channel only). This amp is just a circuit study---- i'll build a circuit to see if i like how it sounds, at the 50 watt level---i have a lot of suitable 50 watt iron laying around and i'll usually build with EL34 x 2 to see how the circuit sounds vs other amps around here. [IMG:800:600]http://i46.photobucket.com/albums/f112/ ... ead007.jpg[/img]

This circuit seems very suitable (also with a footswitchable boot) for a lead channel in a clean/dirty switcher amp @100 watts------ i'll build the 1st one with Sovtek 5881 x 4 because this is the best choice for the iron i currently have on hand---- i'll do later similar builds with KT88 x 4 (@150 watts) after i get some OT's i'm waiting on---i have some custom wound Heyboer PT's that will do the job without breaking a sweat...................gldtp99

[M Fowler]

Can't see the photo at work so will look at it tonight.

Are you going with relay switching as the I believe the schematic is showing vactrol switching.

Mark

[dcribbs1412]

Great info guys thanks
Started a 20 watt based on gldtp99 values/clips
it ended up morphed into a Chubra style build less the diode clipping
...love it thanks

[/url] https://tubeamparchive.com/viewtopic.php?t=14855[url]

now looking for that clean and mean build

This circuit seems very suitable (also with a footswitchable boot) for a lead channel in a clean/dirty switcher amp

any info that can be shared would be appreciated

thanks

Darin

[gldtp99]

Can't see the photo at work so will look at it tonight.

Are you going with relay switching as the I believe the schematic is showing vactrol switching.

Mark

Yes, just a single relay to switch out the 47k ground dump resistor (OD1/OD2) and to switch in the 1uF cathode cap (Gear2/Gear3).
As i said, this build is just a circuit study to see if i like the sound of this circuit (i do)--- to be used as the Lead channel in later 100-150 watt channel switcher heads.
The different AFD/Slash-type circuits, SLO-based lead circuit,etc, etc all sound good but i seem to like this one better---- I picked two possibilities that i liked and will put them on a relay for two different sounds. I'm not worried about relay vs vactrol switching right now--- my version of the rest of the circuit isn't 100% the same as the schematics i have anyway.
i do like the tones/gain levels available and the fact that it needs only three tubes (including PI) to do this preamp. This makes it easier to save space when building a larger, channel switching amp.
The full sized amps will have the Solo boost, too---another relay, for now...................experiments continue- ................gldtp99

[Fischerman]

Have you tried the Bogner Ecstasy circuit? It's very Marshally and the 'rhythm' channel is basically the JCM800 circuit, the lead channel is 5 stages with the last three being the typical 10K cathode stage followed by direct-coupled gain stage/cathode follower pair then tone stack.

I built a simple 2-channel version, clean and lead and stuck a Dumbleator effects loop in it. Actually groovtubin started it and I modded it to hell and back. Looks terrible but sounds pretty good.

I also built a SLO that looks good but doesn't really suit me.

[IMG:800:600]http://i108.photobucket.com/albums/n4/m ... pFront.jpg[/img]

[IMG:800:600]http://i108.photobucket.com/albums/n4/m ... loGutL.jpg[/img]

I should mod this to where I like it and get a cab for it.

[dcribbs1412]

Very nice Fischerman
any footswitches or relay type switching going on

Darin

[M Fowler]

Very nice guys.

Bogner type, the JCM800 channel plus gain channels that sounds like what I would really like to play through. I would love to see the schematic and any data on that if I could.

Mark

[Tone Lover]

I built the quickrod both lead and clean channel I toned it down just a bit with 150k plate instead of a 220k in V1a , there is something very funny I found out about mine. If you have a tube thats microphonic or noisy at all it shows up real bad in the V1 position I actually use it to test all my tubes in for those 2 things (LOL). I have a bad habit of not being able to lay of the bid button at fleabay. Bill

[Fischerman]

Very nice Fischerman
any footswitches or relay type switching going on

Darin

Thanks. Both my Bogner-ish thing and the SLO use Vactrols. There is only one footswitch to switch channels on both amps. There is another toggle switch on the front that switches the gainy channel from rhythm to lead but no footswitch for that. My Bogner-ish amp has the 'circuit' of the Bogner but the architecture of the switching is more like the SLO.

Bogner type, the JCM800 channel plus gain channels that sounds like what I would really like to play through. I would love to see the schematic and any data on that if I could.

Here's all I have. It's not the best and there are some things you have to sort of figure out. I don't have every 470p bypass cap in mine, removing the 'later' ones reduces the brightness without affecting the OD as much, removing the early ones affects the OD more without affecting the brightness as much. Why it uses 499k resistors instead of 470k is a mystery to me. As you can see, it's basically a Fender BF clean channel and a very Marshally channel 2 and 3.

Power supply
[IMG:800:480]http://i108.photobucket.com/albums/n4/m ... XTCPSU.jpg[/img]

PI
[IMG:800:444]http://i108.photobucket.com/albums/n4/m ... rXTCPI.jpg[/img]

FX loop
[IMG:799:310]http://i108.photobucket.com/albums/n4/m ... rXTCFX.jpg[/img]

Channels 2 and 3
[IMG:799:574]http://i108.photobucket.com/albums/n4/m ... TCch23.jpg[/img]

Clean channel
[IMG:797:246]http://i108.photobucket.com/albums/n4/m ... Cclean.jpg[/img]

[Fischerman]

And FWIW, here's a Bogner Fish (preamp) schemo I have:

[IMG:799:521]http://i108.photobucket.com/albums/n4/m ... /Bfish.jpg[/img]

[dcribbs1412]

Thanks Fischerman
really appreciate all this great info
I was interested in the QR also
any info on that one?

Thanks

Darin

[Colossal]

Hi guys,

I've got a Chupa-style hot-rodded Marshall build on the bench right now. Will post when it's done. It's got a ridiculous amount of knobs/features on it and relay switching. Good to see the interest in high gain!