NAD! Jet City JCA22H

[Nightburst]

Hello good people of the forum. It's been too long since I posted anything here!

Today I scored a nice little amp: the Jet City JCA22H and I'm trying to get familiar with it. So far I really like how it sounds, what else can I say? I'm pretty sure many of you have tried this amp or even own it.
I got the older version with the 333 logo. I'd love to hear your findings/experiences on this little beast!

What I like about it: for a 20W amp its very loud, has a lot of gain on board and has a nice dark British voicing that has tons of potential.
What I don't like about it: it does not do cleans very well on the crunch channel. On the lead channel I think the notes can use a little more 'clarity' as they can tend to sound a bit mushed together. I guess one can say it simply lacks headroom on both channels.

Any ideas on tubes and mods I can do to get the most out of this amp would be greatly appreciated. So far I read that a set of TAD EL84 can make a big difference in headroom and bass response. But there are many different types so I'm open to any suggestions. As far as mods go, I'm not sure yet what would make a difference. Maybe a transformer swap in the future but that's way too early to decide since its a costly procedure.

[devastone]

Re: NAD! Jet City JCA22H

Even on the crunch channel, I don't think you can get to the point where headroom is an issue, it just has a lot of gain. I had the 50W version and did some mods to the crunch channel so I could switch between the normal gain and a "real" clean mode. They are great amps, especially for the $, and those mods are easy.

[Nightburst]

Re: NAD! Jet City JCA22H

Yeah, just watched a video of Mike Soldano doing a Choke,Depth and vintage mod. Are those the mods you did/refer to? Remember what tubes you liked in yours?

[devastone]

Re: NAD! Jet City JCA22H

No the mods I did were to reduce the gain in the crunch channel. I put a toggle on the front panel so it was switchable between stock and clean when on the crunch channel.

[dystrust]

Re: NAD! Jet City JCA22H

I'm guessing that devastone is talking about a clean / crunch switch which is copied from a Soldano SLO.

To answer the OP's other question, different preamp tubes really help the congestion. I replaced the stock mystery 12AX7s in my JCA with EH 12AX7s and the gain didn't change much, but clarity was greatly improved. I've been thinking about installing a clean / crunch switch as well since I can't really get clean tones with the gain on the crunch channel higher than about 1.

[Nightburst]

Re: NAD! Jet City JCA22H

Yes, tubes will be the first thing I'll change. Would love to hear any other combinations that have worked for you guys.

[devastone]

Re: NAD! Jet City JCA22H

I'm guessing that devastone is talking about a clean / crunch switch which is copied from a Soldano SLO.

Yes, similar to the SLO circuit, I don't remember it exactly off the top of my head though, you should be able to find it with a little googling.

[Nightburst]

Re: NAD! Jet City JCA22H

I was thinking about tubes today and I came up with this list:

P1 JJ EL84
P2 JJ EL84
V1 ?
V2 Sovtek LPS
V3 ?
V4 Loop? Stock.
V5 Something Balanced

What do you guys think? The internet is loaded with so much different info, I rather trust the ears of the duncan forumees! I'm worried that all JJ's will make this amp too dark but I do not want other tubes make it too bright either.
I'm aiming for a cleaner crunch channel and an american soundig lead channel. I will be playing through V30 speakers so I'm not worried I will be short on mids or highs.
From what I undestand is that V1 is both channels shared, V2 is the lead channel, V3 is shared/cathode follower (not sure what it means), V4 the fx loop and V5 the Phase Inverter. Is this correct info?

[Hank-]

Re: NAD! Jet City JCA22H

I would get a TAD ECC803 for the loop & cathode follower spot. Reliable & balanced sounding. For PI either Sovtek LPS, JJECC803S, EHX 12AX7 or Mullard RI(long plate). I would recommend TAD EL84s, they sound balanced to me, neither too bright or dark.

V1, V2 & V3 are upto you, depending on how you want it to sound. Some good options are Ruby, tungsol ri & newer short plate mullard ri, jj ecc83s as well if you like it. Meh, you are gonna want to try rolling different ones in there any way down the road, so just go with the the ones that get good reviews for now.

[Nightburst]

Re: NAD! Jet City JCA22H

Thanks Hank. Why the LPS for PI? I thought that its a super high gain tube.

[misterwhizzy]

Re: NAD! Jet City JCA22H

You want headroom? Put a 12AU7 in the PI slot. Really in this amp, I think you're hearing that tube compressing more so than the power tubes. I've tried an Amperex, a JJ, and a Chinese 12AU7, and they all sounded about the same as each other, but really increased the headroom a lot.

[Hank-]

Re: NAD! Jet City JCA22H

Thanks Hank. Why the LPS for PI? I thought that its a super high gain tube.

They are generally well recommended for the PI since their triodes come closely matched by default. They may squeal a bit in v2 spot with high gain & decent volume.. There aren't any rules though, if you have that tube with ya then try it in the last spot and see if yu like the feel/sound of the amp change for good or worse.

[Nightburst]

Re: NAD! Jet City JCA22H

Thanks guys, I just got back from band practise and the amp sounded really good at those volumes too. I talked to a local tech also and he gave me some tips for mods and tubes that will work well.
I'll post my stuff once I am done modding, together with soundclips and more pictures.

[Nightburst]

Re: NAD! Jet City JCA22H

First impressions on the choke I installed:

I did not expect it to make such a noticeable difference, I hoped it would but it's quite significant. It really does take the 'sag' out and tightens things up but more important, it adds a nice low end thump! I didn't even have to turn the amp up loud to notice the difference right away.
If you own this amp, I'd recommend this mod. (Warning: Do not mess inside a tube amp if you don't know what you are doing!!!)

No sound clips yet, I'm sorry.