NAD: Ceriatone Hot Rodded Plexi King Kong 50

Part 2 of 5

1/18/22:​

  • Ran shielded cables from channel 1, Gain control (input & wiper) for later connection of both to turret board.
  • Ran Shielded cables for Channel 1 Master Volume control (input & wiper) for later connection of both to turret board.
  • Connected PTFE wires to 12v relay board #1 for later connection to destination.
  • Mounted 7812, 12v voltage regulator on DC terminal strip.
  • Ran power supply wire (W1) from 12vdc terminal strip to Relay Board #1 input.
  • Connected Red Jumper wire from 12v relay board #1 to 12v relay board #2.
  • Connected remaining shielded cables to 12v relay board #2.
  • Connected remaining shielded cables to 12v relay board #1.
  • Ran W3 wire from Relay Board #1 to 5 pin footswitch jack.
  • Ran W2 wire from Relay Board #2 to ‘Channel’ mini-switch, then from ‘Channel’ mini-switch to 5 pin footswitch jack.
  • Installed & secured completed, wired 12v Relay boards 1 & 2 in chassis.
  • Connected Yellow 5vac supply wires from PT to voltage doubler board.
  • Connected short Red & Orange PTFE wires onto voltage doubler board for later connection.
  • Connected Black Ground PTFE wire onto voltage doubler board for later connection.
  • Connected long Red W5 & Orange W6 PTFE wires to Voltage doubler board for later connection.
  • Installed voltage doubler board on chassis wall nearest PT.
  • Connected Black ground PTFE wire from voltage doubler board to star ground.
  • Connected short Red & Orange PTFE wires from voltage doubler board to 12v DC terminal strip.
  • Connected long Red W5 & Orange W6 PTFE wires from voltage doubler board to 5 pin footswitch jack.
  • Install screen resistors 5w, 1K resistors at V4 & V5.

1/19/22:​

  • Filed turrets & cleaned Turret Board 1.
  • Wired buss wire & PTFE jumpers on turret board 1 (TB1).
  • Measured & soldered PTFE flying leads on underside of TB1.
  • Filed turrets & cleaned Turret Board 2.
  • Wired buss wire & PTFE jumpers on turret board 2 (TB2).

1/20/22:​

  • Measured & soldered PTFE flying leads on underside of TB2.
  • Positioned wires from chassis for connection on TB2.
  • Installed TB2 into chassis.
  • Connected Preamp Tube wiring.
  • Connected HT1 from HT Fuse to TB2 with OT CT & 2nd Choke connection to end of TB2.
  • Connected ‘Z’ to TB2.-Connected S5 wire from half power switch to TB2 (with 1st choke connection).
  • Positioned wires from chassis for connection to TB1.
  • Installed TB1 into Chassis.
  • Connected wiring between TB1 & TB2.
  • Connected S3 from standby switch to parallel pair diodes on TB1.
  • Connected ‘X’ to bias supply circuit on TB1.
  • Connected F1 & F2 to 4 x diodes square on TB1.
  • Connected F3 & F4 to end of TB1.
  • Connected HV supply to middle of parallel diode pair on TB1.

1/21/22:​

  • Terminated remaining grounds from TB2 to pot buss.
  • Terminated pot side PTFE wires at appropriate pot/switch.

1/22/22:​

  • Placed components in all turrets that will receive shielded cable.
  • Soldered remaining shielded cables with appropriate component to TB2.
  • Re-checked values of all electrical components.
  • Populated & soldered components onto turret board.
  • Cathode & Coupling Caps: Vishay MKT1813
  • Tone Stacks: Sozo Yellow
  • PI: TAD Mustard

1/23/22:​

  • Reviewed layout & checked continuity of all connections.
  • Tie wrapped wires as appropriate
  • Ran twisted pair from PI Grid leaks to 10K resistors on pin 5 of V4 & V5.
Click to expand...
 
Part 3 of 5

Final Checks​

1/24/22:​

  • Trimmed excess wire, etc. & inspect solder joints.
  • Blew out chassis with compressed air.
  • Checked all Ground connections.
  • Double checked layout, all grounds, all solder joints, & wire connections.
  • Installed Testing tubes for startup.

Start Up​

1/25/22:​

  • With testing tubes in amp, Connected Current Limiter & went thru start up with amp thru 1x15, 8-ohm test cab.
  • Amp squealed. OT phase is reversed. Swapped Grid wires from PI. Amp passing signal and is quiet.
  • Formed Caps at prescribed voltage intervals.
  • Tested switching between solo & MV on Ch. 2. Works well.
  • Connected amp to 2x12 cab.
  • Tested to confirm all controls are functioning properly.
  • Replaced testing tubes with new tubes.
  • Biased amp.
  • All voltages stable.
  • Played amp briefly. Sounds great! See ‘Sound Test’ below.

Expected Amp Voltages:​

  • V1a: 120-150vdc (Drive gain stage)
  • V1b: 190-210vdc (Drive gain stage)
  • V2: CF stage (Drive gain stage/Tone stack)
  • V3a: 120-150vdc (Clean gain stage)
  • V3b: 150-180vdc (Clean gain stage - parallel with V3a)
  • V4: CF stage (Clean gain stage/Tone stack)
  • V5: 230-240vdc (Phase Inverter)
  • V6&V7: 470-490vdc (Output)
  • Plate Voltage: 483vdc
  • Screen Voltage: 479vdc
  • Bias (testing tubes): 33.9/35.5mV

Tubes:​

  • V1: NOS Mullard 12AX7
  • V2: NOS Raytheon 12AX7
  • V3: NOS RCA LP 12AX7
  • V4: NOS GE 12AX7
  • V5/PI: NOS Sylvania 12AX7
  • V6 & V7: Sino China - EL34A Matched Pair
  • Plate Voltage: 483vdc
  • Screen Voltage: 479vdc
  • Bias Voltage: 33.9/35.5mV

Test Speakers:​

2x12 with G12C-25 Greenbacks.

Transformers & Choke:​

  • PT: Ceriatone Plexi 100 (350/350v)
  • OT: Ceriatone Plexi 50
  • Choke: Ceriatone 5H - 50w

Internal Wiring:​

Board to Pots​

  • Shielded wire for sensitive areas, i.e., main input grids, gain pots & effects loop.
  • Purple to Presence pot.
  • Yellow for Resonance pot, NFB to impedance selector
  • Blue, Red & Shielded to Treble & Bass controls.
  • Yellow to Mid control.
  • Orange between Tone controls.
  • Purple (twisted) from PT to board Rectifier.
  • Blue & Red from board to Filter Caps & HT Fuse.
  • Yellow from Choke to board.
  • Green for Grounds.
  • White & Orange to pilot light.

Board to Tubes​

  • Red for Plates.
  • White for Grids.
  • Yellow for Cathodes.
  • Red/Blue for Heater Filaments.
  • White & Orange from Board to power tube grids
Click to expand...
 
Part 4 of 5

Sound Test - King Kong 50:​

1/25:​

Played the PRS CU22SH thru both channels. This amp sounds great! Very quiet too. Ch. 1 is very Plexi-like with a lot less gain than Ch. 2. It can get pretty crunchy, but even with the ERA switched to diode clipping, it’s not as nearly as saturated as Ch. 2. It has a very sweet clean channel, with maybe a hair too more bass than needed, but sweet mids & a nice chimey top end. It may be a bit too sweet. It’s all relative. The controls have a lot of range and it’s not harsh at all. I’m changing the slope resistor to knock a bit of bass out & eventually decide if not needs to be a bit hotter. Ch. 2 is a screamer! It’s super thick & can get super saturated like many ‘Jose’ style designs. It’s a flamethrower for sure! It’s voiced a lot like the Yeti, but it’s even a bit tighter & punchier. I can think of lots of ways to tweak this amp, but it really doesn’t need it. It’s an awesome amp as is. Still, I am going to play it for at least a few days before making any changes. However, I’m going to go ahead & try a couple other clipper pairs & change the Slope R on Ch. 1.

1/26/22:​

I made a couple small changes… I swapped out the clipper circuits with higher rated (1.3w) 20v zeners, new MPSA06’s and a 2N5401/2N5400 in series for Asymmetrical on the Solo switch so I can A/B the two via the footswitch. The OD channel is super tight & punchy. Sounds great! More to come…

1/29/22:​

This thing rips! Beautiful cleans & killer ‘Jose’ style lead channel with Solo MV… great layout for sure! Very versatile. I think the clean channel could use a bit more gain. Still, the channels complement each other very nicely as is. The Solo MV is a great touch to an already killer amp.

2/11/22:​

I think I’m going to see if I can give the clean channel a bit more gain & see how that does. It’s a really nice sounding channel, just maybe a bit more polite than I’d like. As for the lead channel, I’m going give it a bit more time.

2/18/22:​

I made a few changes to the clean channel. I took it to Cameron CCV specs. except for the clipping diodes in the modern mode. It’s not bad at all, but I think I’m going to change it more towards a Plexi style circuit.

2/19/22:​

Tested changes made to Clean Channel. I’m going to leave these changes, at least for a couple weeks as this could be the way she stays. I really like the couple minor changes I made on the clean channel. It has a very sweet, clean tone & can get a bit crunchy when pushed as well. It’s a very versatile amp overall for sure.

3/31/22:​

I’ve decided to parallel the currently unused ‘b’ half of V3, the input stage for the Clean channel. I expect this will give it bit more gain & thicken it up a bit. Also, I am going to exchange the transistor clippers for 12v/12v zener pairs. I like the 12v/12v pair a lot. Makes a great alternate to the 20v Zeners. There’s less volume drop too.

4/1/22:​

The few changes really made an already excellent amp. even better! Parallel triodes on the clean channel really do give it more character & body, as well as a bit more gain, and it still cleans up beautifully. I plan to wire the drive channel to Chupa Specs. at some point as I prefer the Chupa over the Yeti. This OD channel can be wired to either pretty easily. I may wait and leave the choice up to the buyer. Whichever they prefer. If I set it up as a Chupa, I’ll need to change the NFB a bit as well. It should be a bit looser, in keeping the Chupa vibe.

2/20/23:​

This amp sounds KILLER! I don’t think it needs any changes. I’m staying with the Yeti-like drive channel. I think the tightness is spot on for this amp.
Click to expand...
 
Part 5 or 5

Final Design Specs (King Kong 50)​

Channel 2 (Drive)​

  • DC Heater Filaments for V1 & V2: 6vdc
  • OD Channel Input Network: Gamma - 1M/0.1uf (Dale MF/Xicon)
  • V1a grid stopper: 56K (Dale MF)
  • V1a Cathode: 3K/1uf (carbon film/Vishay MKT1813, 250v)
  • V1a Plate: 330K (carbon film)
  • V1a Coupler: 0.0022uf (IC MWR)
  • Ch. 2, Gain 1: 1MA
  • Ch. 2, Gain 1 bright caps: 1000pf (Ceramic 2kV) & 2700pf (NOS Russian)
  • Feel Switch: 82K/10M (Carbon Film)
  • V1b grid stopper: 150K (Dale) 0.001uf (Sozo) to ground
  • V1b Cathode: 3K/1uf (carbon film/Vishay MKT1813, 250v)
  • V1b Plate: 100K (carbon comp)
  • V1b Coupler: 0.022uf (IC MPW)
  • Ch. 2, Gain 2: 1MA
  • Ch. 2, Gain 2 bright caps: 1000pf (NOS) & 2700pf (Ceramic)
  • Divider into V2a: 470K (carbon comp)/510pf (Silver Mica)
  • Rear Panel P. Trimmer: 1MA from V2a grid to ground
  • V2a Plate: 100K, 3w M.O.
  • V2a Cathode: 820R/1uf (carbon film/Vishay MKT1813, 250v)
  • Cathode Follower: 100K (PRP)
  • Ch. 2, Master Volume: 1MA
  • ’Jose’ MV Array: 10K (PRP)>0.33uf (Xicon)
  • MV ERA Switch Clippers:
  • 12v/12v, 1w Zener diodes (Modern)
  • 20v/20v, 1.3w Zener diodes (80’s)
  • Ch. 2, Solo Master Volume: 1MA
  • Solo ERA Switch Clippers:
  • 12v/12v, 1.3w/1w Zener diodes (Modern)
  • 20v/20v, 1.3w Zener diodes (80’s)
  • 8K2 (Carbon Comp) compliance resistor from diode pairs to ground (Squash)
  • Tone Slope: 39K (PRP)
  • Tone Stack: .022uf/.022uf/560pf (Sozo/silver mica)
  • Voltage Droppers: 10K, 3w (Metal Oxide)
  • Dual axial 50x50uf dual filter cap on turret board

Channel 1 (Plexi):​

  • Clean Channel Input Network: 1M/0.1uf (Dale MF/Xicon)
  • V3a+b shared grid stopper: 56K (Dale MF)
  • V3a Cathode: 820R/0.68uf (carbon comp/MKT 1813, 250v)
  • V3b Cathode: 2K7/0.68uf (off board-carbon comp/MKT 1813)
  • V3a+b shared Plate: 55K actual-2w carbon comp)
  • V3a+b Coupler: 0.022uf (IC MPW)
  • Ch. 1, Gain: 1MA
  • Gain 1 bright caps: 1000pf & 4700pf (Ceramic)
  • Divider into V4a: 470K/510pf/470K to ground
  • V4a Plate: 100K, 3w M.O.
  • V4a Cathode: 820R/0.68uf (carbon comp/MKT 1813, 250v)
  • Cathode Follower: 100K (PRP)
  • Ch. 1 Master Volume: 1MA
  • ’Jose’ MV Array: 10K (PRP)>0.33uf (Xicon)
  • ERA Switch Clippers:
  • 12v/12v, 1w Zener diodes (Modern) -20v/20v, 1.3w Zener diodes (80’s)
  • 8K2 (Carbon Comp) compliance resistor from diode pairs to ground (Squash)
  • Tone Slope: 39K (PRP)
  • Tone Stack: .022uf/.022uf/560pf (Sozo, silver mica)
  • Voltage Droppers: 10K, 3w (metal oxide)
  • Dual axial 50x50uf dual filter cap on turret board

PI / Power Section:​

  • PI Input Caps: 0.022uf & 0.1uf (TAD Mustard)
  • PI Grid Leak: 1M & 1M (PRP)
  • PI Cathode: 470R ohms (PRP)
  • PI Tail: 10K ohms (PRP)
  • PI Caps: 0.1uf & 0.1uf (TAD Mustard)
  • PI Load resistors: 82K & 100K (Carbon Comp)
  • PI Snubber cap: 100pf, 1kV (ceramic)
  • Power tube grid leak resistors: 220K (PRP)
  • Presence cap: 0.1uf, 0.33uf, 1uf (Xicon) & 5K Pot.
  • NFB: 56K @ 8-ohm tap (PRP)
  • Resonance pot: 1MA with 4700pf, 2200pf, 470pf, 27K (ceramic/carbon film)
  • Screen Resistors: 1K, 5w (Vishay - wire wound)
  • Bias Caps: 2x 10uf (BC Components)
  • Bias Resistors: 47K, 15K & 27K (PRP)
  • Diodes: 1N4007 (x5)
  • Filtering: 50x50x50x50x50x50x50x50xx150x50x50x50x50uf
  • Main Droppers @ Filter cap cans: 4x 470K, 3w
  • Dropper on TB2: 12K (2w metal film)
  • DC Heater Supply: (on TB1): 4x 4700uf & 4x 1N4007 diodes
  • Power Tube Grid Stoppers: 10K (PRP)
Click to expand...
 
Any of you guys tried or heard the JoeJoe 50? Haven't looked for vids yet but sounds interesting.
 
Never heard of the JoeJoe50. What is it based on?

I usually check in on Ceriatone once or twice a year to torture myself while trying to avoid adding amps to the stable again.
 
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