NAD! JCA50H content

[misterwhizzy]

Well, she's here! First things first. This amp is really fun to play. Sure, there are some things to be desired, but at $330 brand new, it's a deal that's nearly impossible to beat.

Out of the box,

it's too gainy and mushy.

I'm firmly convinced that's because of the cheap preamp tubes. All five appear to be bottom-of-the-barrel Chinese tubes, and it was pretty obvious they needed an upgrade. I put in a Mullard RI and a JJ ECC83s in V1 and V2, respectively. Still a little loose, so I swapped the PI with an EHX 12AU7, which cleared things up quite a bit. Seems to be very, very sturdy and well-made.

The clean channel can go from pretty chimey to a pretty thick crunch, and that's where the overdrive channel takes over. There's more gain there than I think anyone could possibly consider musical. Tons of sustain, harmonics leaping off the fretboard, very saturated. You know the drill. Like I said, a lot of fun to play.

So what's not to like about it? Two things, and one is strictly personal preference. I just don't really like the way 6L6s compress. I'm VERY strongly considering modding it to EL34s if I get confirmation the PT can handle it (and I think it can). I'm sure that's part of what keeps it tight, but my ears just love the EL34 sound. The second is kind of a serious flaw in the amp, and that's the loop. Engage anything, and the volume drops massively. I'm sure it's due to the expectation of a line-level signal, but I don't have any rack gear.

Here's the rig now, because I promised pics.

[devastone]

Re: NAD! JCA50H content

That is a great deal!

You can probably e-mail Jet City or Soldano and ask about the PT, don't see why they wouldn't tell you.

As far as the fx loop, IIRC it's the same circuit as the SLO, and relatively easy to mod to be instrument level. The other solution is to look into an Ebtech LLS-2 line level shifter.

[Nostalgic Distortion]

Re: NAD! JCA50H content

"The other solution is to look into an Ebtech LLS-2 line level shifter."

^^^LOL, that was exactly what I was going to suggest!!!^^^

My buddy bought one of these the other day & it just arrived yesterday. When I spoke with him last night he said that after trying the head out he basically said that the only complaint he had was the volume drop when the loop was engaged as well...

For that price I was tempted to grab one myself but I'm already on pretty thin ice with the wife because I just charged a $300 set of pickups & a new Wampler Plexidrive Deluxe right before Christmass so probably best to sit back licking my wounds for the time being...

[devastone]

Re: NAD! JCA50H content

The LLS works well, I had to use one with my Randall RM50 head that also had a really hot loop, and that was to use pedals that were supposed to be able to handle line levels (sounds like the same complaint about the Soldano/JCs).

[slaveunit]

Re: NAD! JCA50H content

I think that I read somewhere that they did not recommend using el34s due to transformer.

[Toe-Knee]

Re: NAD! JCA50H content

You can mod the loop to be ~0db but it does change the tone of the amp slightly but it is just a single resistor and cap.

With regards to the pt shoot me a pm

[Nightburst]

Re: NAD! JCA50H content

Congrats on the amp! Jet city makes amazing stuff for the money, perfect backup/ budget choices. I e-mailed Jet City a couple of times with questions and Doug himself always responded quickly and detailed, I can appreciate that!
I think the whole idea of the amps is to mod them to your wishes anyway. Before you go crazy on the PT and power tubes I suggest checking out what populair mods are readily available that will improve the clarity, feel, compression, tightness etc.
I have the JCA22H and a tung sol in V1 made a significant change for the better. For JJ's I like the gold pin pre amp tubes a lot, they are a little more expensive but less feedbacky and less mushy than the regular ones.

[misterwhizzy]

Re: NAD! JCA50H content

Yeah, I've dealt with Doug several times. Excellent customer service, quick response, etc. I had the power lamp go out on my JCA20H, and he emailed me a replacement free of charge.

I've done more tube rolling in the JCA20H, and I've done many mods, some good, some bad. I had the slope resistor on a switch before deciding I liked the stock value and just pulled the switch. I modded the power section to lower the bandwidth a bit to reduce the sharp highs of the EL84s, and I added a switchable bypass capacitor on the second gain stage to thicken up the lower mids. So I'm definitely familiar with Jet City and modding.

And that brings me to today's edition. I replaced the screen grid resistors in the 50-watter for 1k 5 watters, and swapped the power tubes for EL34s. Biasing with the stock trimpot sucks, but I got it done. It's a fire-breather now. The crunch channel is really bright, unfortunately, so balancing that and the overdrive with a shared EQ is a bit tough, but I'll figure that out. Likely, I'll just switch to the neck for cleans and use the overdrive channel for heavy rhythms and boost it for leads. The master volume seems to be very good, and it seems to take boosts and overdrives very well. If we're being totally honest, though, it's probably because I'm just not used to having headroom in my amps.

It wasn't all a bed of roses. After I finished biasing it, I got no sound at all out of the amp. Uh-oh. Turns out without the footswitch plugged in, you don't get any output. But I was sweating it for a bit.

It's not perfect yet, but it's getting pretty close. The shared EQ issue will never be solved, but I think some tube swaps could get things real, real close to completely awesome.

[Toe-Knee]

Re: NAD! JCA50H content

Yeah, I've dealt with Doug several times. Excellent customer service, quick response, etc. I had the power lamp go out on my JCA20H, and he emailed me a replacement free of charge.

I've done more tube rolling in the JCA20H, and I've done many mods, some good, some bad. I had the slope resistor on a switch before deciding I liked the stock value and just pulled the switch. I modded the power section to lower the bandwidth a bit to reduce the sharp highs of the EL84s, and I added a switchable bypass capacitor on the second gain stage to thicken up the lower mids. So I'm definitely familiar with Jet City and modding.

And that brings me to today's edition. I replaced the screen grid resistors in the 50-watter for 1k 5 watters, and swapped the power tubes for EL34s. Biasing with the stock trimpot sucks, but I got it done. It's a fire-breather now. The crunch channel is really bright, unfortunately, so balancing that and the overdrive with a shared EQ is a bit tough, but I'll figure that out. Likely, I'll just switch to the neck for cleans and use the overdrive channel for heavy rhythms and boost it for leads. The master volume seems to be very good, and it seems to take boosts and overdrives very well. If we're being totally honest, though, it's probably because I'm just not used to having headroom in my amps.

It wasn't all a bed of roses. After I finished biasing it, I got no sound at all out of the amp. Uh-oh. Turns out without the footswitch plugged in, you don't get any output. But I was sweating it for a bit.

It's not perfect yet, but it's getting pretty close. The shared EQ issue will never be solved, but I think some tube swaps could get things real, real close to completely awesome.

The best thing to do with the crunch channel imho is install the bright switch and the clean /crunch switch from the SLO.

It makes that channel a lot more usable. I pretty much use it exclusively clean these days as it balances perfectly with the lead then and it's a pretty good clean.

If you check out http://www.guitarampboard.com/forum/...pic.php?t=1615 there's plenty of mods that are well detailed.

[misterwhizzy]

Re: NAD! JCA50H content

One more note on today's tone shakeup. This head likes the Governor/Wizard combo much better than the Green Beret pair I had in there yesterday. Plus I have no worries about overpowering that speaker pair. But it's much tighter, almost to a Fryette level, and thick, glorious gain. Great amp at any price, but the sale MF had on made it completely irresistible. And the EL34s are a big improvement.

Anyone want to buy a pristine Blackstar HT-5 head? ;-)