Switching things up.

[misterwhizzy]

Yes, it's the most misleading title of all time. So sue me.

A while back I installed a cathode bypass capacitor on the second gain stage of my Jet City to boost the gain on the higher frequencies a bit. I put it on a push pull pot that controlled the depth in the power section. Here it is before I started messing with it.

I ended up pushing or pulling the pot any time I went to switch from dirty to clean, and it was just a hassle trying to find it on the back of the amp and pull or push the pot straight out without turning it at all. It's a nice feature, and it does its job, but it's hard to access. So I decided to put a hole in the front of my amp. I've never done this before.

View attachment 31777

I set it up so I can add a second switch later, because I'm still thinking of one more thing I may want to add on the front panel before everything's said and done. I removed the depth pot, desoldered the cap and the wiring, ran new wiring around the board after I twisted it together, and soldered it to the new switch at the front of the amp.

View attachment 31779

Made sure everything was soldered properly, buttoned it up, and here we go.

View attachment 31780

I think it may have dropped the noise floor a little bit as well, but it may just be wishful thinking or the PI tube I swapped out last week, but it seems to work pretty well. I'm slightly disappointed in that the effect is not as drastic as I remember. Since it takes so little time to switch the setting now, I can hear the differences more quickly now and rely on my tone memory less. It definitely adds some hair and smooths out the highs, but it's not as dramatic as I remembered.

Anyways, I'm glad a forum member suggested this mod to me, and I won't out him in case he doesn't want to be named, but thanks, dude.

 

[glassman]

Re: Switching things up.

Nice work Will, that looks very professional!

 

[zzmoore]

Re: Switching things up.

Their PCB is much "better" than I imagined.
Guess the real estate is what I am looking at.
If that were a Boogie board, it would be 60% smaller.
Well Done

 

[Lazarus1140]

Re: Switching things up.

Looks great, Will!

 

[misterwhizzy]

Re: Switching things up.

Thanks, everyone. The important part is that it sounds good and that it's accessible. The fact that it doesn't look awful is just a bonus.

By the way, should I rotate the switch so that it's vertical?

 

[Soulcrusher_X]

Re: Switching things up.

Thanks, everyone. The important part is that it sounds good and that it's accessible. The fact that it doesn't look awful is just a bonus.

By the way, should I rotate the switch so that it's vertical?

While you're at it, install one of those red safety guards that you see on fighter jets and nitrous systems on race cars. ;-) You ready to add the FX loop and clean channel yet? lol

 

[Soulcrusher_X]

Re: Switching things up.

Did you switch the 803 out of the PI?

 

[misterwhizzy]

Re: Switching things up.

While you're at it, install one of those red safety guards that you see on fighter jets and nitrous systems on race cars. ;-) You ready to add the FX loop and clean channel yet? lol

Dude, Mojotone is backordered on those kits until late this month. At that point, though, yes. At least as far as the FX loop goes. I still don't have a plan on the clean channel.

And your post made me think of the clear plastic covers you see over the "Launch Nuclear Weapon" switches in cheesy movies. You know, the red one with the keyhole next to it?

Did you switch the 803 out of the PI?

I have to know how you knew that. This is the only way I can see that you would have known. If you were able to figure it out from the pictures, I'm amazed, because the PI tube is sitting right behind the big 333 logo.

The bottom line is that the 803 got a little mushy under high gain. The string separation on the chords really suffered as well. It's all detailed in the thread I linked to above, but it freaked me out, because I thought I was getting old and needed to turn down the gain. I just can't have that.

 

[Soulcrusher_X]

Re: Switching things up.

Haha. hadn't seen the thread yet. I actually haven't been reading the forum as of late. Been doing crazy duty with the kids, so my time has thinned out a bit.

I might have influenced you a tad to revisit the 803 a while back when we were having a tube rolling thread with mwalluk, so I just took a guess that the aforementioned PI being swapped out was the 803. *cough*cough* I mean, I saw it behind the 333 logo...yeah. lol

And turning down the gain? No way. Just add some mids. Always works for me.

 

[misterwhizzy]

Re: Switching things up.

Haha. hadn't seen the thread yet. I actually haven't been reading the forum as of late. Been doing crazy duty with the kids, so my time has thinned out a bit.

I'd say you had been sorely missed, but I'd be lying. I'm just glad someone cares enough to read my thread. Thanks for all your help with the ideas on this amp.

I might have influenced you a tad to revisit the 803 a while back when we were having a tube rolling thread with mwalluk, so I just took a guess that the aforementioned PI being swapped out was the 803. *cough*cough* I mean, I saw it behind the 333 logo...yeah. lol

Yeah, that long-plate JJ works pretty well, especially on cleans. But under the gain, it smushes together, and not in a good way. More like the South Park parody of Snooki way. Once you Google it, you'll find that hilarious. Anyways, once I put in my old Amperex 12AU7, it cleared things up quite a bit.

 

[Soulcrusher_X]

Re: Switching things up.

I'd say you had been sorely missed, but I'd be lying. I'm just glad someone cares enough to read my thread. Thanks for all your help with the ideas on this amp.

Glad I could help, bro. And admit it. You missed me. lol

Yeah, that long-plate JJ works pretty well, especially on cleans. But under the gain, it smushes together, and not in a good way. More like the South Park parody of Snooki way. Once you Google it, you'll find that hilarious. Anyways, once I put in my old Amperex 12AU7, it cleared things up quite a bit.

Just before selling the JSX, I tried the 803 in the PI and it wasn't quite as good in that amp, like your JCA. It worked great in my MKIII probably because that amp is tight and sometimes unforgiving, so adding a little "squish" made it easier to play. I could just be talking out of my hoohaa, but I'm sticking to it. lol

Good to hear the JCA is still rocking hard. I'm kinda tempted to pick one up and do some experimentation.