Voodoo Lab

Hi all.
I know this is WAY off topic but i'm desperate for some help cause i'm megggga confused by all the terminology and technical terms when it comes to electronics and stuff... If anyone has seen my most recent posts you'd have gathered i'm getting some pretty elaborate ideas for my rig... I'll try to boil it down to it's most simplest form for the sake of this post though...

Guitar -> FX pedals -> signal splitter into three amplifiers..
1) Marshall JMP-1 pre-amp (Not power amp, no power amp attached)
2) Krank Revolution Series 1 head (all tube preamp, poweramp, mono FX loop)
3) Roland JC-120H (SOLID STATE preamp, poweramp, no fx loop, line outs...)

Then all three amps are blended into my System Mix Plus, which has stereo cabtone circuitry built into it so i can just D.I. into recording desks and PA's at for gigs.

*Note i haven't actually purchased the JC-120H, i'm still organising it with a seller, but it's pretty much 99% definately in ---- i love that clean sound!!!!*

Anyway, i've read you ALWAYS need to keep the speaker attached to your head if you switch it on.

SO! i'll sum the Left and Right outputs from the System Mix Plus into a 2x mono to 1x mono Y cable and plug that into the Krank, so i use the Krank cab as a mono personal monitor..

The Marshall JMP-1 is just the preamp so no poweramp is necessary. Beautiful -- that means i don't have to worry about a cab!

This leaves the Roland JC-120H though. I really do not want to use any more cabinets. I don't want to damage the JC-120H though, but i don't want to take more cabs just to run it safely..
So i look at buying a load box, which i guess you could say it "tricks the head" into thinking there's a speaker there (makes it operate safely without a speaker)..

This is all okay, i'm happy to buy two load boxes (for the L+R of JC-120H) but i just read on THD's website to NEVER use a Load Box on a SOLID STATE amp!!!

So now i'm pretty stumped!
Can anyone help me out here, please! I'm confused by all this stuff.

I don't want to buy the load box/es unless i need them. if i need to buy them i don't want their cab simulator stuff, i'm totally wrapped in the System Mix Plus Cabtone circuitry, i just want to use the load boxes AS A LOAD BOX -- no D.I. stuff, it's not needed..

I know this post is a little long and i'm aware it's quite off topic than the usual posts on here, but as mentioned, i'm absolutely baffled and am desperate for someone to chime in with their knowledge to help me out :S

Any assistance would be greatly greatly greatly greatly appreciated guys!
If anyone can tell me why i should or shouldn't use a load box with a solid state amp, and what type of unit i should buy if i need to, that would be great. i just really want to understand what it is and how it all works together so my equipment can outlast me!!!! LOL!!

So yeah, i hope to hear from somebody soon -- looking forward to hearing your replies.
Cheers guys, take it easy..
Thanks again (in advance),
Dawesy.

I'm not quite sure what the best route to go for the JC-120 would be but I can say that your idea of summing the two outputs of the System Mix Plus with a Y cable is not right. A Y cable can be used to split a signal, but should never be used to sum two signals.
Are you running anything in stereo to begin with? Without knowing what else you are running into the System Mix Plus, I cannot say what a better option would be but it looks so far as if your "monitor" amp would only need a mono signal... wait a minute... I'm lost again... isn't the Krank that you want to use as a monitor amp part of the three amps that you are blending with the first stage of the System Mix Plus? I think you have some 'asplanin to do!

Hahah yes the Krank's PRE-amp section will be blended in the first stage of the System Mix Plus but the blended sound would (ideally) then be run back into the Krank's FX Loop return - the power amp, to use the Krank cabinet as my personal monitor (or just stage cab anyway..) also the Krank's FX Loop is completely in series.

The attached picture is (once again, for time and space sake, a simplified version of) what i'd like to do, but i'll definately be using more stereo fx, and as noted down the bottom of the pic, the JC-120H has no fx loop, or "return" jack. So i can't use it's power amp section for my personal monitors. (That's why i'm wanting to use the Krank's --mono-- power amp)

So any speakers attached to the JC-120H only carry it's sound and nothing from my mixer. Which means it's not worth plugging speakers into it considering my sound is 'better' through the System Mix Plus --- add to that the additional weight and real estate of two speaker cabinets, i'm pretty much dead set on going without! lol!

(i see carrying two cabs for a clean amp as redunant when the clean sound is already elsewhere and i have more than just the clean sound to consider..)

Problem is i don't know if i can safely operate the JC-120H without a load on it -- BUT i don't know if i can use a load box on it, since it's completely solid state. Oh the confusion!!

One of my students is an electronics whizz and suggested just 'removing' the power amp section completely (not physically, just electronically!!) but, i'm sure you've gathered i don't know what'd be involved due to my lack of knowledge on these things. and i'm not to keen on doing any crazy modifications to such a beautiful -and rare --and discontinued!!--- classic amplifier!

Any ideas on what i should be doing ?

All the GCX loops should have the signal coming from the Send jacks rather than the Out jacks. Connecting it the way it is drawn will make the status LEDs be backwards where the LED will be off to indicate that the amp/effect is on... a little counter intuitive. I assume that the Amp Selector is used just for the three way split and that all its outputs are active at all times?

Where you have the outputs summed with a Y Cable should not be done... either feed just the Left MIX 2 Out signal to the Krank Effects Return or get a second power amp and cabinet if your monitor must be stereo.

I fairly sure that the JC-120 can just be run without any load because it is solid state... no internal mods needed.

John! Mate!!! You're a machine!!!

As always, you're right - the Amp Selector will stay out reach in the back of my rig, with all outputs active at all times. Cheers for the heads up with the LED's too, lol I wouldn't have even noticed this until tucking all my cables away and making it impossible to alter hahah!

I'll not use a Y-cable to SUM a signal, only ever to split it, though may I ask out of simple curiousity why it should never be done? Would it double the volume going into the Krank poweramp?

I'll run the Mix 2 Left Output into the Krank and the Mix 2 RIGHT Output into another guitarist's amplifier's Return jack... Either that or fire up the ol' 9200 and run its Left and Right outputs into two half stacks or something..I've never used two half stacks in place of a quad though, so I guess we'll have to play that one by ear (cue drum fill!)

To anyone else on the forum reading this, if you have any experience with VHT power amps, please share your stories!! I'm sure I've seen some in Vernon Reid's early-90's rig and his live tone is so clear (check out bonus tracks on their Time album just for starters!) plus from memory Nuno Bettencourt was championing VHT's for a while too -- does that sound right??
What do you guys reckon, what's everybody's favorite power amp?

Excellent news about the JC-120H not needing speakers John, thanks (again) for the help! I've asked quite a few people about this and they've all said the same thing - Solid state = No need for speakers. This means if I do go with the stereo power amp option I'll just need one loadbox for the Krank.

Also out of curiousity, what actually happens to a tubed amp if you use it without attaching a speaker to it?

Thanks again mate, can't thank you enough!!
Everyone else, GET INVOLVED!!! I really wanna hear all of your opinions and ideas!
You all rule!
Cheers - Dawesy.

Summing two outputs with a Y cable actually connects the two outputs together as if you had simply connected a patch cable from one to the other. Summing outputs should be done with a mixer, just as you are doing with your preamp outputs into MIX 1 of the System Mix Plus. This keeps each output from "seeing" the others and prevents any potential for damage to the electronics driving these outputs.

Running a tube amplifier's power amp section with no load will damage the output transformer... a costly repair. With a tube power amp it is better to run a dead short on the output than to run it open for any length of time.

And because I know you didn't mean to exclude us from your poll... we love our Fryette (formerly VHT) Two/Fifty/Two. It's loud as hell and clear as the midday sun!

Nice!! I just thought that sadly VHT had stopped making power amps didn't know about the name-change....COOL!!

I'd have never thought that sorta thing could happen with a Y-cable so cheers for setting me straight hahah

With a tube power amp it is better to run a dead short on the output than to run it open for any length of time.

Well... It's time for me to enrol in an electronics course!!!

What are the other favored amps and pedals and gear-in-general getting regular use in the Voodoo Lab cave John??

dawesy1986 wrote:What are the other favored amps and pedals and gear-in-general getting regular use in the Voodoo Lab cave John??

I'll get some pics put together and post in the Rigs section... stay tuned!

Check out the Man Cave gear over in the Rig pictures section.
http://www.voodoolab.com/forum/viewtopic.php?f=5&t=1387