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Not bad but not great that is pretty low volume, you're not moving the speaker/air at those levels, no matter the amp it'll never sound great on a / or multiple 12" speakers at 70/80dB, even if you drive the tubes with an attenuator. You've got to move a minimum amount of air. Somewhere around 90/95 already shows a massive improvement, and not really that loud, like a loud tv i'd say

Little late to the party but just picked up an original JCA100 that needed some work. Well all new tubes and replaced screen grid resistor and BAM up and running. I could hear the potential and reading thru lots of these threads and others decided to start replacing parts.

First up are all the coupling caps with Vishay Mkt368's. Yep instant upgrade, much clearer and open sounding. Has that Soldano bite now. Also changed output coupling caps to SLO spec .47's and now its moving some air. Next up all the ceramics as they are pretty cheap. Also changing out filter caps in the preamp with Panasonics and same values as SLO. This should loosen up the feel and improve the tone as well.

Honestly for $200 used plus some tubes and $20 in parts this is a mighty good sounding amp.

Well, I'm getting an Amelia this Friday so I thought I should bring this thread back. I'll be posting some clips and videos when I get it.

So I've had this amp for about a week now. My first impression was I really liked it. Then I had mixed feelings about it. I was concerned it wouldn't be punchy enough or loud enough. First practice with it, I struggled with it a bit, it was passable but not really good. Then I spent more time dialing it in for a few days and finally nailed it. Last night practice was awesome and the amp flat out kicked ass!!!

I am still undecided whether I will be using the Amelia or the 5153 for the King's X show next week. Right now I am leaning more towards the Amelia but the 5153 is a safer choice since I've already played several gigs with it. We'll see.


Anyway, a few things about this amp:

1-It's voiced very much like an old Marshall and it has to be dialed in like one. For example, the bass control needs to be kept in check or the amp gets flubbly. I use the same trick I've used with NMV Marshalls : set the Bass to zero, then turn it up while chugging the low E. As soon as there is some low end in the tone, stop. So I have the Bass set to 2-3 and it's great.
Also, the channel volume/master volume balance is key to get the best out of this amp. I started with the channel volume around noon and using the master to set the overall volume. That's how it was for my first practice with it. It's ok but not where the sweet spot is.
I then decided to set the master volume really high (around 7) and use the channel volume to set the overall volume instead. That woke the amp up. Huge difference in punch and tone. Problem is it gets SUPER loud fast. I'm talking old JMP loud. But the tone is incredible when dialed in this way. I also have the Master Volume 2 nearly maxed for my lead volume and it really feels like playing through a cranked NVM Marshall. Really good.

2- The effects loop in this amp it's an improvement over the Soldano loop but still very picky and hard to use. I first tried the Donner delay I was using with the 5153 and it's unusable with this amp, there's a huge volume jump when the effcet is engaged. Then I tried the DD3 and it was fine, but the repeats sounded a bit distorted. I finally tried the G3n and after struggling with it for a bit, I was able to set the level correctly in the Zoom unit to make it work with the effects loop. The effects sound great now but it took quite a bit of tweaking to get there. JCA is advertising this amp's loop as "pedal-friendly", but I disagree. I think it's still better suited to multi-effects/rack units where you can control to input/output level of the effects.

3- the stock pre amp tubes suck. They don't sound bad but 3 out of 4 were microphonic. JCA should definitely up their QC on tubes, I had the same issue with the 100H I bought in the past. I have enough experience with tube amps to know it's just a tube issue, but a lot of people don't know about these things and could simply write off the amp as defective - especially at this price point, since it would be a first tube amp for a lot of people.

4- that said, once everything is dialed in, it's seriously fucking good. It's most definitely not a plug-and-play or intuitive amp, but when you get it right, damn it's flat out killer.

I still need to make a demo of it, but it will be at the fest for sure.

Mochi wrote:I just come here to show off the mod i've done on my JCA50h, and I don't believe there's any talk of this on this topic.
I added a sweep pot (like on krank amps). It was a nice guy on the Official JC group facebook page that told me how to do it.
For the metal-heads like myself it tightens up the amp a fair bit, you can go from a boatload of mids to very scooped. Anyways I'm loving it, if anything i'd say it"s more important on the "to do" list than the depth mod, and equally as easy to do !
On a 50/100h you just have to replace the r24 resistor with a 100k linear pot, on a 22h it's r26 that needs to be replace with the pot and on a 20h it's r21.

Anyways here's a quick video I did.

Boost : MXR M77 od in front.
Pickups : BKP WARPIG alnico V
Cab : jca24S+ with V30
Mic : Tbone MB75

[video]https://www.youtube.com/watch?v=10Q5F6f2xbQ[/video]

Slope resistor mod http://www.guitarampboard.com/forum/viewtopic.php?f=5&t=1615&start=50#p50598 in "sweeping" mode?

Correct, not limited to one value, that being said you can also put different values on a switch once you've found 2 - 3 sweet spots you like, or you can just mark them on the pot as well, pot is definitely more flexible, allows for a more accurate amp/cab tuning.
Another really easy mod to do as well (probably been pointed out here already) is a Hi/tone-cut ala vox, to take out some of the high end harshness (and also makes the presence more usable), a .0047uf cap on a 250kA pot between the 2 outputs of the PI, did miracles for me. I'm at the point now where I'm getting rid of my 5150II because the jca50h sounds infinitely better to my ears.

Mochi wrote:Correct, not limited to one value, that being said you can also put different values on a switch once you've found 2 - 3 sweet spots you like, or you can just mark them on the pot as well, pot is definitely more flexible, allows for a more accurate amp/cab tuning.

OK, so mid balance like stock position (r24) becomes one of spots on 100k linear pot?

Mochi wrote:Another really easy mod to do as well (probably been pointed out here already) is a Hi/tone-cut ala vox, to take out some of the high end harshness (and also makes the presence more usable), a .0047uf cap on a 250kA pot between the 2 outputs of the PI, did miracles for me. I'm at the point now where I'm getting rid of my 5150II because the jca50h sounds infinitely better to my ears.

phase cancellation circuit, what about volume drop? make another quick video

Lignjun wrote:

Mochi wrote:Correct, not limited to one value, that being said you can also put different values on a switch once you've found 2 - 3 sweet spots you like, or you can just mark them on the pot as well, pot is definitely more flexible, allows for a more accurate amp/cab tuning.

OK, so mid balance like stock position (r24) becomes one of spots on 100k linear pot?

Mochi wrote:Another really easy mod to do as well (probably been pointed out here already) is a Hi/tone-cut ala vox, to take out some of the high end harshness (and also makes the presence more usable), a .0047uf cap on a 250kA pot between the 2 outputs of the PI, did miracles for me. I'm at the point now where I'm getting rid of my 5150II because the jca50h sounds infinitely better to my ears.

phase cancellation circuit, what about volume drop? make another quick video

Yeah it basically changes the frequency on which the mid pot acts upon, mainly adding or removing low mids to my ears, sounds a bit like what that isf pot does on blackstar amps, one way more fenderish and the other way more marshallish.

The hi-cut does induce a loss of volume depending on where you set it, I mean you can still achieve ear blowing volumes, it makes the channel volume more progressive a lot less touchy, if you remove the cap and just leave the pot it would serve as a master volume, with the cap it doesn't act as a master volume but does still drop the volume, where I was on 2 I now go to 3 for example, but definitely makes the amp easier to play at lower volumes.
I will do a quick video, maybe today.

Here is a demo video, on high gain and "clean" (can make the clean really chimey as well, really nice hadn't even tried it on the crunch channel yet)

[video]https://youtu.be/OLJLxBoOyxo[/video]

Mochi wrote:Here is a demo video, on high gain and "clean" (can make the clean really chimey as well, really nice hadn't even tried it on the crunch channel yet)

Tnx. Hearing it this way, it seems there's a lot of the volume drop if you cut extremely, on the other hand, this thing can be much louder than needed these days with modern sound engineering and monitoring. Small stages, big stages, I've never had any chance to crank it.
Well, thanks to your first video I've decided to do sweep pot. What I don't like about stock h50 is mid balance and it seems this mod solves that very thing. Hi cut looks like nice upgrade after that.

Lignjun wrote:

Mochi wrote:Here is a demo video, on high gain and "clean" (can make the clean really chimey as well, really nice hadn't even tried it on the crunch channel yet)

Tnx. Hearing it this way, it seems there's a lot of the volume drop if you cut extremely, on the other hand, this thing can be much louder than needed these days with modern sound engineering and monitoring. Small stages, big stages, I've never had any chance to crank it.
Well, thanks to your first video I've decided to do sweep pot. What I don't like about stock h50 is mid balance and it seems this mod solves that very thing. Hi cut looks like nice upgrade after that.

You're welcome !

Yep there's a fair amount of volume drop when you go extreme (adds a fair amount of volume as well when you go to the other extreme) but I don't think you'll go into any of those two extremes really , neither one sounds particularly pleasent TBH, one is way to bright and the other is way too dull.
And then yeah as you say they can dish out plenty of volume anyways so even with a decent amount of cut there's still enough power, I haven't had any volume problems, still gets painfully loud
Without the tone cut you can still roll off the treble to reduce the bite, but there's something I like when combining the tone cut set pretty low and the presence cranked way up there's a kind of really nice (to my ears) frequency shift when you go past 8 on the presence (you can hear it really quick at 2min02 in the video).

The downside to all this is that it's adding two major tweak knobs that have a lot of effect on the overall tone, so it makes the amp way less plug & play

I'm really happy with the stock 50H I have... The only thing I want to do is reduce the noise on the drive channel. I know there's a simple mod for that, but I can't seen to find it anywhere.

GuitarBilly wrote:I'm really happy with the stock 50H I have... The only thing I want to do is reduce the noise on the drive channel. I know there's a simple mod for that, but I can't seen to find it anywhere.

What kind of noise? If it’s him then the heater mod will help.

GuitarBilly wrote:I'm really happy with the stock 50H I have... The only thing I want to do is reduce the noise on the drive channel. I know there's a simple mod for that, but I can't seen to find it anywhere.

If you want to buy the mod it’s probably listed here:
https://www.epic-tone.com

Hi guys,

I just joinded the Forums because i received my Jet City Amplification JCA50H today and would like to change the Pretube amps, but i cant seem to get the chassis open ^^. Can somebody help me?

Oh and which position would be V1?

Thanks in advance!

Benjamin

Folks, been looking for a little bit. Bought JCA custom 22 head with 2x12 earlier in the year. Nice amp, very simple, rock n roll. Glad to be here.

Benjamincf wrote:Hi guys,

I just joinded the Forums because i received my Jet City Amplification JCA50H today and would like to change the Pretube amps, but i cant seem to get the chassis open ^^. Can somebody help me?

Oh and which position would be V1?

Thanks in advance!

Benjamin

V1 is by the input jack. You don't have to remove the chassis. Just take off the back panel.

I'm getting my new 100 LTD today. Can't wait. It's out for delivery now.

Double posting like a noob.

GuitarBilly wrote:I'm getting my new 100 LTD today. Can't wait. It's out for delivery now.

What's the verdict?

18% off at ampfactory.com this week.

Ippon wrote:

GuitarBilly wrote:I'm getting my new 100 LTD today. Can't wait. It's out for delivery now.

What's the verdict?

It's a great amp. Quite a different tone and feel from my 50w with the 6L6s.

The crunch channel with the EL34s is a dead-on 2203 clone. Much more so than the DSL green channel. Anyone looking for an 800 on a budget should look into this amp.

The drive channel is exactly what it claims to be, a cross between a Marshall and a Soldano. It does lack a bit of the thump of the 6L6 version. I think this amp is a great candidate for the depth mod. But on the other hand, the lead tone is creamier and more fluid.

Before using JCAs again, I was playing Marshall DSLs for a long time and I think this amp does the modern Marshall thing just as well, if not better.

I will probably build a simple rig with pedals around this amp and just use it as a single channel on crunch, it is really amazing how close to a 2203 it is, but with a better master volume and a loop. It's a real sleeper for sure, JCA should push this amp more based on the crunch tones alone.

The SLO-100 Overdrive and Decatone Crunch are my top 2 guitar tones. I've always dreamed of having them both in the same [cheap] amp.

Can any amp gurus look over this Decatone schematic and offer any feedback on whether it's possible to modify a 100H for Decatone Crunch and SLO Overdrive?

Thanks!!!!

The SLO mod can be done for sure...

The Decatone can be done too... but that amp has a slightly different tone stack than the SLO and since the 100H only has one tone stack, it would be hard to do both. So it would be either one or the other...