New guitar amp

Settled for Wontons & noodles afterwards. My buddy finished up a birthday-gift Champ for his brother, so we fired up the shop Strat through that and compared CCTs with NOS RCA... OMG, I still can't get over how different and better old tubes are compared to new cheapo stuff.

My 5E3's board is finished wiring, and some sundries such as caps on pots, grounding of pots, pre-amp tube sockets mounted... next up I'll try to get all the transformer wiring done.

Next time I'll order the pizza in advance and pick it up for self-delivery; Gotta practice for the job market in Canada...
 
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Well see there's lots of low end and then there's lots of tight low end... In stock form a 5E3 has so much low end it turns to mush because the weeny power transformer can't supply enough juice to reproduce those notes.
 
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I like a tight bottom, who doesn't?

HamishR, I defer to your wealth of experience!

I'm a bit of a blank slate (as many have said about me), I'm coming from a bass-sick background so it's good to learn more about guitars, amps, weeny power transformers and tight bottoms.

I'll be back at the 5E3 tomorrow night.
 
I would always check with the manufacturer or supplier of the power transformer as to whether it can support the power tubes you want to use. But I would say that if the PT can run EL34s it should be fine with KT66s.

My only reservation with building anything with KT66s is that good KT66s are difficult to come by. Jjjimi is spot-on though when he says that a JTM45 will have a BIG clean sound. And his recommendation of Valve Storm is spot-on as well. The chassis and hardware from Valve Storm are as good as it gets. You can use KT66s, EL34s or 6L6s in a JTM45 usually. I like KT77s which are like a really good EL34.

I've built the TMB MV 18W amp from Trinity and it's not bad but not as big a sound as the JTM45. As Jjjimi says though you can get it sounding good at potentially lower volumes. The other Marshall I would look at - and it is louder again than a JTM45 - would be the 1987. When built in a '67-68 spec it is one of my favourite amps. The low end is more solid than a JTM45s, which can get a bit flabby with extreme drive. It has beautiful cleans if you link the channels with a patch cord and when cranked there are few better sounds in rock'n'roll - and few places you can play that loud unfortunately. But it does take pedals well.

As a pedal platform, a great gigging amp, and something with exceptional clean tones I would recommend something like a Fender tweed Bassman built as a 2x10 or 1x12. You can buy kits for a 5F6-A Bassman and put the chassis in a range of cabinets - Mojotone could probably built you a cab with both a 2x10 baffle and a 1x12 baffle, for example. I have built a few 1x12 Bassmans with Mojo cabs and they sound awesome. After all, the JTM45 was heavily based on the 5F6-A Bassman. The Bassman sounds sweeter and the JTM45 a little more rock, but for the volumes we generally have to play these days the Bassman is possibly a better all-rounder.
What filtering do you like for mains, screens, PI and preamp in a 67 or '68 style 1987? And did that era 1987 have the 2.7k and .68 on v1b yet? Do you like the .022 or .0022 coupling cap on bright channel? Sorry for all the questions lol.

Btw I have something weird going on with one amp..maybe you would have an idea? Somehow I can manipulate or subtly seemingly shift the tone if i move any given knob on a pedal plugged into the amp while all pedals are off and true bypass as well (positive). If i strum my guitar and simultaneously move a pot on a pedal that is off I can hear my tone change. This is some marshall clone I bought a few years ago but it's always done this. The guy that I bought it from told me there was some circuitry built into the amp that drains the caps for him so he could mess with it I think...idk but I've never been able to figure it out but its definitely the amp
 
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EL84s like it's bigger brother the EL34 tend to break up relatively early because they are true pentodes and not beam power tubes, like the 6L6, KT66, 6V6, KT88, etc.
On similar sized tubes, a pentode will always break up earlier than a beam tube.
To the OP, It depends what you want. You want clean or breakup? You want to practice/gig with it or you want something that won't piss off the neighbors?
Best thing to do is try different amps to give you a general idea of what you're looking for...
To the JTM45 guys... If you're getting to this level of amplifier, spend a little extra and get/build a JTM45/100 type amp. It's one of the best sounding amps ever made... Really, and it's not just a double helping of the JTM45, it's so much more.
And NO master volumes!!! Sheesh...
 
Hey Mrvibes85: It depends on the sound you're shooting for, but the last 1987 I built had two 50/50 can caps on the chassis and a 32/32 on the board and it sounds incredible! The filters will alter the feel more than the sound. If you use all 50/50s it can get very hard rock, but the differences aren't night and day.

I started off with the old shared cathodes on V1 - 330µF with an 820 resistor - but in the end I wanted more variation so went with the .68µF/2K7 on the bright channel and a 250µF/1K5 for the normal channel. Historically the normal channel had the 330µF/820R combo but that means the triode is biased quite cold, so I used the 1K5 to give it a bit more pep. You could even use just a 25µF cap there too - it won't really make much tonal difference and might tighten things up a bit. I rarely use a bright cap on the volume pots but did use an 100pF on the bright channel this time and a 470pF cap on the mixers - the 470K resistors linking the channels.

I haven't tried a .0022 on the bright channel as a coupling cap but can see why folks do. I usually play these amps through one or two 12" speakers in an open back cab so like the extra beef of the .022. And I have kept the .1µF PI coupling caps. If I used a quad box I'd probably use .022s there but with open-back smaller cabs I like the extra low end punch.

FWIW I have used 6V6s in plexis before and they work very well to bring the volume down a bit, but they can still be quite loud! They lack the brutal punch of an EL34 but still sound like a Marshall.
 
Hey Mrvibes85: It depends on the sound you're shooting for, but the last 1987 I built had two 50/50 can caps on the chassis and a 32/32 on the board and it sounds incredible! The filters will alter the feel more than the sound. If you use all 50/50s it can get very hard rock, but the differences aren't night and day.

I started off with the old shared cathodes on V1 - 330µF with an 820 resistor - but in the end I wanted more variation so went with the .68µF/2K7 on the bright channel and a 250µF/1K5 for the normal channel. Historically the normal channel had the 330µF/820R combo but that means the triode is biased quite cold, so I used the 1K5 to give it a bit more pep. You could even use just a 25µF cap there too - it won't really make much tonal difference and might tighten things up a bit. I rarely use a bright cap on the volume pots but did use an 100pF on the bright channel this time and a 470pF cap on the mixers - the 470K resistors linking the channels.

I haven't tried a .0022 on the bright channel as a coupling cap but can see why folks do. I usually play these amps through one or two 12" speakers in an open back cab so like the extra beef of the .022. And I have kept the .1µF PI coupling caps. If I used a quad box I'd probably use .022s there but with open-back smaller cabs I like the extra low end punch.

FWIW I have used 6V6s in plexis before and they work very well to bring the volume down a bit, but they can still be quite loud! They lack the brutal punch of an EL34 but still sound like a Marshall.
Right on, I like the .0022 better for lead playing and the .022 for rhythm but the .0022 as well as the .1 or .047 PI coupling caps give me a nice medium. I think the .0022 allows for a better cranked tone like that IMO with either bucket or singles. I also have never been crazy about volume bright caps unless I'm using a lower value bright mixer cap across the mixing resistors but I think that's because I was always trying to build an amp that teeters on bass and lead specs for the best of both worlds but after having a jtm45 and jtm50 I put together I've learned to embrace the 4700 or 5000pF cap on the volume on lead circuits.

Yeah, I was curious about the filtering because I find conflicting schematics for those years. I like 100 and sometimes 64 for mains on lead models and either 50/50 on PI and screens or 32/32 and I've actually never used anything in the preamp besides a 32/32 in any amp. Depending on the rest of the circuit I find that going from 64 mains to 100 yields a less forgiving tone/feel that sometimes works and sometimes doesnt IME.

I wish I could figure out this old plexi clone, I'm gonna take it apart piece by piece and see if I can hunt down what's going on. To me, the problem seems like a power issue, maybe the PT or whatever "circuitry" the guy had installed to drain the caps. It's the weirdest problem though. Get this, if I am plugged directly into that amp with no pedals in chain but I have a pedal power supply and a few pedals plugged into the same outlet or power conditioner as the amp then I can actually hear the tone change when I turn on the pedals that arent even in the chain! Its not the pedals effect that I'm hearing but theres a small tonal shift and I can even change the sound by turning the pedals controls that arent in the chain. Wild lol.

Edit: I found the problem. It was a tiny string of solder that had dripped from the tab of volume pot touching the rest of the pot.
 
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