Is this different than the Park 45/100? The B+ being on the 550V tap leads me to believe it's a 45/100 with an 4k OT spec'd for KT66 tubes. The high OT Z and the high plate V (which would also be too high for the screen grid if on the same rails) would explain the red plating. Changing to the 500V tap should be OK with JJ el34s, which have a rare 500V screen rating, but the OT Z might still be ~2.5x the recommended amount, and might still cause redplating. In that case, running it with just one el34 pair should alleviate the problem, and have more highs. If the owner insists on running el34 tubes with a 4k OT, he should also consider the simple raw bias tap to screen grid mod that self-regulates grid current, but running beam tetrodes would then not be posible.
I also wouldn't use a Carbon Comp resistor for the bias feed. CCR's can change value a lot with temperature, and it's not a signal path resistor. A metal film resistor there shouldn't affect the tone.
@@GCKelloch kt66 would be the "correct" tube here for sure, especially with the full b+. I'm not certain on the OT spec, but good shout to keep that in mind!
Sounds amazing! Back in the early 90s in the punk rock and skateboard days, we had Park heads show up here and there, and were always the "cheaper" Marshalls, so no one paid much attention to them even though they sounded great. Oh boy there was so much rad gear to be had at good prices back then. If we only were more aware.
wow look at the guts of this amp beautiful ,I love your knowlege and equipment you use ,I thought I subbed a few months ago but resubbed ,and I get to watch any videos that I missed which is a bonus for me !!!1
Wow that thing sounds fantastic.... clear, articulate, percussive and weighty all at the same time. I'll bet a light OD that cuts a little bit of low end would be crushing in front of that once cranked 👍
Oh yeah, I imagine it takes pedals extremely well. Plenty of room to cut low end on the EQ too, I'm very impressed with the circuit. I've been back and forth on what I want to do with my JMP, which started life as a Super Bass. If I was set up to rely more on pedals I think super bass is a great circuit.
Had a chance to buy a PARK in 1977 for peanuts and passed it up. One my my greatest regrets ! Those who knew, knew !! Massive clean power with beautiful power tube overdrive !!
Good work as always, for the size of the amp she can push some big sound waves , now to be honest I heard a park amp before but that was way back in the early 90s and there was a garage band but I don't think it sounded this good they more like a clash type band , anyway thanks for sharing it's always a treat watching your videos
Yeah there have been MANY incarnations of Park amps over the years. They range from incredible examples from the golden era of Marshall to solid state garbage practice amps and everything inbetween haha. In the early days, they were exactly the same minus the exterior aesthetics as their equivalent marshall counterparts.
It looks like it's been back and forth at least once before it came to me. I don't think an el34L would be enough, KT series would be the move at the full voltage setting and no variac.
500V+ plate voltage itself is not a problem for EL34 tubes because max plate to cathode voltage of them is much higher than 500 volts. In datasheets there are class B output stages using 700 volts and two EL34's gives around 80 watts output power. They were used as PA amplifiers etc. Idle bias current of those amps is of course very low.
@YeatzeeGuitar I understand. BTW in many high B+ voltage amps lowering screen voltages (even by adding a dedicated lower voltage node for them if necessary) takes care of too hot bias problem, tube failure (screen overheating) problem, and usually makes amp sound smoother as well.
@@YeatzeeGuitar Oh sweet man! That's awesome! Great vid dude, keep it up. I have a 69 JMP 50 1987T (with a tube rec), so a bit of an oddball, and my only vintage amp, but it needs a little love. It's working, and sounds pretty good, but I know it's not sounding it's best, and theres a few odd things going on in the circuit. Just having a hard time finding tech's I trust up here in old Canada hah. I might try take it on myself, but have a little more learning to do. I'm almost there though I feel like It's mostly learning how to take all the measurements at different points on the amp that I'm still trying to learn how to do properly, but I'm getting better at reading schematics, and that, and can solder just fine hah.
I'd recommend joining an amp tech FB group and/or EL34 forum. Lots of helpful people at either to help walk you through it. You'll get a wave of "DONT TOUCH IT TAKE IT TO A PROPER TECH" folks on FB inevitably, but you can just ignore them and keep on keeping on. Everyone has to start somewhere.
If you don't care about the tech-y stuff, and just want to hear the amp played jump to 23:13 🙂🤙
Is this different than the Park 45/100? The B+ being on the 550V tap leads me to believe it's a 45/100 with an 4k OT spec'd for KT66 tubes. The high OT Z and the high plate V (which would also be too high for the screen grid if on the same rails) would explain the red plating. Changing to the 500V tap should be OK with JJ el34s, which have a rare 500V screen rating, but the OT Z might still be ~2.5x the recommended amount, and might still cause redplating. In that case, running it with just one el34 pair should alleviate the problem, and have more highs.
If the owner insists on running el34 tubes with a 4k OT, he should also consider the simple raw bias tap to screen grid mod that self-regulates grid current, but running beam tetrodes would then not be posible.
I also wouldn't use a Carbon Comp resistor for the bias feed. CCR's can change value a lot with temperature, and it's not a signal path resistor. A metal film resistor there shouldn't affect the tone.
@GCKelloch we've got a line on a piher to replace it, just won't happen on video 🙂
@@GCKelloch kt66 would be the "correct" tube here for sure, especially with the full b+. I'm not certain on the OT spec, but good shout to keep that in mind!
The 1.75k Merren OT's have a 1.5" core stack. The stack in the OT in this amp looks thicker from the looks in the video. It might well be a 4k model.
I'm normally not a Marshall guy, but holy crap, that's a great sounding amp! Nice work!!
She's a beast!
Sounds amazing! Back in the early 90s in the punk rock and skateboard days, we had Park heads show up here and there, and were always the "cheaper" Marshalls, so no one paid much attention to them even though they sounded great. Oh boy there was so much rad gear to be had at good prices back then. If we only were more aware.
They're such cool amps in retrospect!
Great job! Sounds killer! I could see Ty Tabor rocking this amp totally.
I love those pseudo-chicken head knobs. You sound killer through that amp! Thanks for sharing this. It’s gorgeous.
🙏
They are called "banana" knobs!
It is a beauty,very well build and great sound,I just love this stuff!
wow look at the guts of this amp beautiful ,I love your knowlege and equipment you use ,I thought I subbed a few months ago but resubbed ,and I get to watch any videos that I missed which is a bonus for me !!!1
Haha thank you sir!
Can hear the DNA with the Bassman. Great amp! Lot of amp, but it sounds BOSS!
💪
That looks like something a real amp nerd put together. Well done, Mitch.
Wow that thing sounds fantastic.... clear, articulate, percussive and weighty all at the same time. I'll bet a light OD that cuts a little bit of low end would be crushing in front of that once cranked 👍
Oh yeah, I imagine it takes pedals extremely well. Plenty of room to cut low end on the EQ too, I'm very impressed with the circuit. I've been back and forth on what I want to do with my JMP, which started life as a Super Bass. If I was set up to rely more on pedals I think super bass is a great circuit.
Sounds like a killer Hiwatt in a way but unique in itself! Beautiful amp!
Sounds great!
Had a chance to buy a PARK in 1977 for peanuts and passed it up. One my my greatest regrets ! Those who knew, knew !! Massive clean power with beautiful power tube overdrive !!
That sounds so good!!
Beautiful amp
Really is!
Sounds really good
Great video!
Thanks!
Good work as always, for the size of the amp she can push some big sound waves , now to be honest I heard a park amp before but that was way back in the early 90s and there was a garage band but I don't think it sounded this good they more like a clash type band , anyway thanks for sharing it's always a treat watching your videos
Yeah there have been MANY incarnations of Park amps over the years. They range from incredible examples from the golden era of Marshall to solid state garbage practice amps and everything inbetween haha. In the early days, they were exactly the same minus the exterior aesthetics as their equivalent marshall counterparts.
And thanks!
I just got a p45 like 5 days ago!
Epic!
On those Lar/Mar’s is it a good idea to put the resistors that normally would be on the board, on the pot, in case the pot or a side of the pot fails?
@@Skoora the lar/Mar adds safety resistors you'll see from the wiper to the bias feed connection on the pots to maintain some bias if it fails
Man, I didn’t even see them until I zoomed in. 👍
nope. luv the tech-y stuff. what is the value of the cbc & resistor @ v1? & is it electrolytic?
Just put JJ Kt77 in it or e34Ls to handle the extra voltage. Don’t change anything on that masterpiece!!
It looks like it's been back and forth at least once before it came to me. I don't think an el34L would be enough, KT series would be the move at the full voltage setting and no variac.
500V+ plate voltage itself is not a problem for EL34 tubes because max plate to cathode voltage of them is much higher than 500 volts. In datasheets there are class B output stages using 700 volts and two EL34's gives around 80 watts output power. They were used as PA amplifiers etc. Idle bias current of those amps is of course very low.
@@jutukka more concerned with the screens
@YeatzeeGuitar I understand. BTW in many high B+ voltage amps lowering screen voltages (even by adding a dedicated lower voltage node for them if necessary) takes care of too hot bias problem, tube failure (screen overheating) problem, and usually makes amp sound smoother as well.
Music Man amps run 700+vdc on EL-34s totally diff tube config tho, id encourage you to lookem up, .....
Are you in the US brother?
@@jamescassidy4045 yessir. SoCal
@@YeatzeeGuitar Oh sweet man! That's awesome! Great vid dude, keep it up. I have a 69 JMP 50 1987T (with a tube rec), so a bit of an oddball, and my only vintage amp, but it needs a little love. It's working, and sounds pretty good, but I know it's not sounding it's best, and theres a few odd things going on in the circuit. Just having a hard time finding tech's I trust up here in old Canada hah.
I might try take it on myself, but have a little more learning to do. I'm almost there though I feel like It's mostly learning how to take all the measurements at different points on the amp that I'm still trying to learn how to do properly, but I'm getting better at reading schematics, and that, and can solder just fine hah.
I'd recommend joining an amp tech FB group and/or EL34 forum. Lots of helpful people at either to help walk you through it. You'll get a wave of "DONT TOUCH IT TAKE IT TO A PROPER TECH" folks on FB inevitably, but you can just ignore them and keep on keeping on. Everyone has to start somewhere.
BULLSHIT!!! Its a Marshall copy and nothing more. My 1970 JMP will walk all over this hunk of over priced junk.
...?
Agreed
Haha !! Not if it's a vintage Park - If you know, you know !!
Sounds fat. Is there a schematic online?
It's meant to just be a clone of a ~67 super bass I believe. Difference being the PT with multiple winding taps to choose from
Thanks! Is PT beefier in specs I wonder. More electrolytic in filtering? Sounds fatter than normal Marshall would
That's the super bass circuit, much fatter than the super lead
Sorry. Not that great a sound. Not worth 3k$.
Totally! Get a marshall pedal and a fender and save $$$. Pretty much the same thing anyway
I think it sounds great! Seems you're in the minority based on the comments, but as always to each their own 🤙