Bare Knuckle Pickups Forum
Forum Ringside => Guitars, Amps and Effects => Topic started by: Dmoney on September 22, 2013, 09:25:06 PM
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So a while ago this site was being mentioned by Toe-Knee (I believe)
http://www.jetcityamplificationstore.co.uk (http://www.jetcityamplificationstore.co.uk)
I've decided that once I've got my current project out of the way, I'd like to take a close look at a JCA.
I've gone and ordered the JCA22H. Hopefully service from the site will be decent and it'll get here soonish.
I'm going to see what the deal with it is, and then maybe try out some of the SLO mods in it. See how just how SLO it was get and maybe try a few more things along the way.
Anyone hear already have one? I haven't had a lower wattage amp like this kicking around for a bit. Tends to be 100watters in my front room more than anything else. I'm looking forward to it arriving.
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no but i've got the 50 watt head and from what i hear the preamps are the same...
hard to complain at the prices they go for there and on thomann... that's what swung the deal for me :lol:
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Just had a first look at that amp...man that seems interesting ,espcially at that price.
Really really interested on how it comes out with the mods.
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Interesting. Didn't realise they were so cheap. Now I'm very tempted to try the 22w one out! Thanks for the GAS :lol:
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I'm still very tempted to get one of these and make it more SLO like just so I have an amp that i dont care about getting damaged/lost/stolen that I can leave at the practice place.
not that anything like that has happened there as it's actually pretty secure but I would only really want to leave a cheap amp there.
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I found 20watts too quiet for even a practice for me. Should a bit neater at home though.
Hopefully it'll turn up. Not sure about how runs this online store. I have a lot of plans other than to SLOify it. I'm tempted to see if I can squeeze and extra tone stack in there and some other bits and bobs. I have a spare choke I can sling in it, and I can add bias test points. Those should be easy things to do first of all.
I'm still not keen on the aesthetics. I thing they could style them a bit better. The ultra low pricing probably puts people off. IF they are that cheap, they should just think about sticking better iron in it and going after some of Marshall's JCM900 or DSL market. A few upgrades couldn't make them MUCH more expensive?
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I found 20watts too quiet for even a practice for me. Should a bit neater at home though.
Hopefully it'll turn up. Not sure about how runs this online store. I have a lot of plans other than to SLOify it. I'm tempted to see if I can squeeze and extra tone stack in there and some other bits and bobs. I have a spare choke I can sling in it, and I can add bias test points. Those should be easy things to do first of all.
I'm still not keen on the aesthetics. I thing they could style them a bit better. The ultra low pricing probably puts people off. IF they are that cheap, they should just think about sticking better iron in it and going after some of Marshall's JCM900 or DSL market. A few upgrades couldn't make them MUCH more expensive?
The volume is the thing that puts me off. Especially with the other guitarist using a MKIV.
I'll be interested in seeing what you do. From the gutshots i've seen the pcb layout is pretty spacious so will accomodate all kinds of mods.
The ones i saw (22h gutshots) too were loaded with Illinois polys and nichicon electros so it's not exactly bargain basement unbranded rubbish like in the 100h & hdm
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The guts shots I've seen have those blue poly caps, and maybe some that look like Xicons. The filters looks like panasonic's especially the big on for the DC filaments.
I've been trying to think of some ideas. Dual EQ is high on the list if I can figure it out.
The volume would concern me. That old 20watt Avenger I built was fine at home, but in a practice it had to be cranked, so the power amp would be into saturation being driven by an already saturated preamp signal. It didn't sound good and it got really unstable.
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The guts shots I've seen have those blue poly caps, and maybe some that look like Xicons. The filters looks like panasonic's especially the big on for the DC filaments.
I've been trying to think of some ideas. Dual EQ is high on the list if I can figure it out.
The volume would concern me. That old 20watt Avenger I built was fine at home, but in a practice it had to be cranked, so the power amp would be into saturation being driven by an already saturated preamp signal. It didn't sound good and it got really unstable.
The dual tonestack should be pretty simple. In fact if the 22h uses LDRs for switching i have a small pcb layout for adding in a second tonestack unobtrusively.
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It's relays. I need to look into it. I'm not sure about the DC from the cathode follower being fed directly into the relay like those LDR's. Still, could always block the DC with a large cap. There are other options.
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So... it's here already!
Luckily I'm off work so I was in to take it. The crunch channel is pretty crunchy. Maybe more so than my SLO. The Overdrive channel is pretty much what I expected. Doesn't have the most low end but I'm used to have a depth/resonance on my amps, so I just turned the bass up a bit. I did have the dial back the presence way more than I do playing at low volumes on the SLO. Granted this thing and the SLO are very different beasts.
It sounded really fizzy in the high end out of the box, but it is full of chinese valves. Also noticed that the power transformer was pretty warm after I got finished jamming on it. Looks ok inside.
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I swapped a JJ into V1, and it sorted the fizz on my JCA20H.
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I'll probably do that too. I have a few JJ's knocking about. I thought it would be the valves and not the circuit adding that fizz. I want to add a switch so I can change channels with the pedal. That seems like job number one.
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First mod is done. I got tired of needing to use the footswitch with the fixed cable to change channels. My SLO footswitch wouldn't work with it.
So I've installed a front panel channel select which is disabled when a footswitch is plugged in at the back and I put a jack socket on the footswitch and cut off the fixed cable, so now I can use any guitar lead between the footswitch and the head. Pretty easy going.
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Here we go!
I've been having some fun with this. It's more aggressive than a full blown 100watt head I think, but thats probably due to the nature of the EL84's I'm thinking. It is my first ever EL84 amp. It does do things a big amp won't do however, which is cool.
I did some mods! Looking at the big photo and going left to right...
Added the Depth/Resonance control and an extra orange drop as part of that circuit just at the top left of the PCB.
Added 10nf snubbing caps to the rectifier (4x little blue things) to share the rectification task equally between the diodes and reduce switching transients.
Added a Choke (its outside the chassis though).
Added some bias test resistors to easily measure cathode current draw.
Changed the jacks from PCB mounted plastic ones to the isolated switchcraft jacks (just because I had a bunch).
Rewired my front panel channel switch to the new jack.
Swapped the power supply caps for EE series Panasonics, just because I know they are awesome.
Added SLO100 style Clean/Crunch switch, a Bright/Normal switch and what is know as the 'SRV' mod (a mid scoop with a boost of the low and high end) to the "crunch" channel.
Added a bright cap switch to the "Overdrive" channel aka the Haynes mod.
Swapped a few gain pots and resistor values to SLO values.
It's sounding cool still!
Now that the Crunch channel can be knocked down the "Clean", the bleed from the Overdrive channel into that circuit is more noticeable. So I might do a bit of researching and see if i can locate a fix.
Pretty happy with my work on this. It's come out really well.
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^ nice :D
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Clips? :wink:
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I just tried to make a video using my macbook and the built in camera import thing in imovie. the audio however was terrible. All warbled and stuff. I'd like to make a video so people can see what switches do what. Just got to figure out a good way to do it that doesn't require me going out and buying stuff.
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This gives you a vague idea.
I managed to use a little usb audio in/out on my macbook to take the input from my hotplate and run it into garageband where I could apply a cab sim, then use the monitoring output to feed the built-in audio input so I could record the audio while filming in imovie. bit of pain. Also meant I couldn't hear what the recording was like while playing. So I'm just looking at the audio level in garageband to try and even out volume between changing channels.
Most mods effect the crunch channel. Switches left to right are...
Channel switch (under the jack)
Clean/Crunch switch
Bright switch for the Clean/Crunch channel. Switch in up position is Bright On.
SRV mod (mid scoop with boosted lows and highs). This switch pops when I turn it on but that is expected.
Bright cap switch for the Overdrive channel. Disconnects the bright cap when turned on.
The switches in the down position are considered in 'normal' mode. Up is 'On'.
It hasn't come out THAT well, but it gives you an indication of whats up. I noticed I forgot to turn down the depth control at one point. urgh. It isn't the best indication of my playing either! Honest!
http://www.youtube.com/watch?v=PGkOpR8AkCA (http://www.youtube.com/watch?v=PGkOpR8AkCA)
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The more I read about these the more I am tempted. Also seems like a great way to make the jump from pedal building to amp modding.
Please do tell more about how effective and easy the mods were. I assume the amp is damn good value for money even without mods. With them it is insane even or what?
I think I might save towards the 50W combo and try to mod the sh*te outa that one...
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This gives you a vague idea.
I managed to use a little usb audio in/out on my macbook to take the input from my hotplate and run it into garageband where I could apply a cab sim, then use the monitoring output to feed the built-in audio input so I could record the audio while filming in imovie. bit of pain. Also meant I couldn't hear what the recording was like while playing. So I'm just looking at the audio level in garageband to try and even out volume between changing channels.
Most mods effect the crunch channel. Switches left to right are...
Channel switch (under the jack)
Clean/Crunch switch
Bright switch for the Clean/Crunch channel. Switch in up position is Bright On.
SRV mod (mid scoop with boosted lows and highs). This switch pops when I turn it on but that is expected.
Bright cap switch for the Overdrive channel. Disconnects the bright cap when turned on.
The switches in the down position are considered in 'normal' mode. Up is 'On'.
It hasn't come out THAT well, but it gives you an indication of whats up. I noticed I forgot to turn down the depth control at one point. urgh. It isn't the best indication of my playing either! Honest!
http://www.youtube.com/watch?v=PGkOpR8AkCA (http://www.youtube.com/watch?v=PGkOpR8AkCA)
It says the video is private!
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Ah!
what about now?
EDIT: listening to that video on my laptop the day after doing it is pretty embarrassing
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Those generally unbranded Chinese tubes are usually pretty terrible. Some of them have a lot of gain so some people like them for that reason, but the tone quality is still downright awful!
For new tubes that are pretty gainy and fat sounding and don't cost an arm and a leg, I like the Electro-Harmonix 12AX7s a lot. Much better than the JJs which are very thin. Of course now there's Gold Lions and Mullards and a lot of other stuff to choose from as well. I also have some German RFTs and Amperex that I like a lot.
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I that clip im using JJ ECC83S'.
I like them. I feel they offer a good compromise between being mechanically robust and sounding ok.
I have some RFT's, Tungsrams, EHs, Sovteks, a Brimar, a Mullard. A couple different 5751's (JJ, Philips, Sovtek).
I like a nice 5751.
I've kept the chinese valves to one side. In any case, this amp is still bright but not as fizzy up top as before. To be fair though I've made enough changes to the amp to make the original valves sound different again. So a straight valve swap as a test would need to be compared in the amp as it is now. I haven't done that.
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In my TT hardwired the stock valves were not too bad at all, but I still replaced them with a TAD STR set for the power section and a JJ in V1 + a Tung Sol in V2.
While that is always subject to change (I have not even tried Mullards yet in anything but my tube mic) this really appeals to me. I cannot see though how someone would find the JJs to be "thing". I found them to be quite thick, dark and roary, which I like in V1, but I need Tung Sol in V2 to get that something back in there.
I am currently fiddling again since I just got a boob tube also, but even with the TS and my Klone (yeah I freaking love Johnīs work) adding high end and overtones to the JJ I still sometimes feel that I need more openness. Might just be that I am living in student housing and canīt remotly crank it (and the Weber Mini Mass does only so much...it does change the tone after all)), but there is something missing.
Might get another TS or TAD or something for V1 or 2 and if I get lucky a set of Mullard power tubes some time.
Back from the tubes and on topic: I have read this into your posts so far, but do you actually think that the JCA is good value for money? How much does is improve with mods? How hard to do are the mods that make the difference?
Anyone know if the combos are good also? How is the cab and the speakers? Really looking at the 50 combo right now...
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I that clip im using JJ ECC83S'.
I like them. I feel they offer a good compromise between being mechanically robust and sounding ok.
I have some RFT's, Tungsrams, EHs, Sovteks, a Brimar, a Mullard. A couple different 5751's (JJ, Philips, Sovtek).
I like a nice 5751.
I've kept the chinese valves to one side. In any case, this amp is still bright but not as fizzy up top as before. To be fair though I've made enough changes to the amp to make the original valves sound different again. So a straight valve swap as a test would need to be compared in the amp as it is now. I haven't done that.
I've done several A/B tests myself...
I guess some JJ's are okay -- they usually don't go microphonic for a long time and have very low noise. I prefer them to Sovteks and Svetlanas (for preamp tubes) and Eis (because they're very bad for microphonics).
When I AB/D several JJs with a EH though, the difference in sound quality was pretty amazing! And when I compared the EH to the Amperex, the sound got even fatter much in the same effect.
The Amperex could be super compressed in higher gain amps where I thought the EH is pretty safe for any application. RFTs are also a safe bet with any amp too, especially the German ones.
I don't have the knowledge to do my own mods or anything, but I'm the sort of hands on person who's always curious about the differences between every little thing... I found myself buying preamp tubes because those are easy to swap out just to test them out for differences in tone.
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My original point is that the Chinese preamp tubes really are generally pretty terrible. I don't think it's ever worth the extra gain...
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I might try one of the chinese valves in my SLO. They are the first Chinese tubes I've had, although they do look very similar to some Ruby 12AX7's I have. I've never read much good about them.
The long plate JJ ECC803S (I think it's the 803S?) sounds pretty good. I didn't like the RFT so much in my SLO V1 but it wasn't bad, I just prefered the Tungsram. The Ei's I had sucked too. The Mullard I have sounds rubbish in everything. Just goes to show you what a name alone is worth.
Sometimes I swap em around and find a new combo I like. I keep meaning to try the Tung Sol Reissue.
The JCA is very good value for money. My JCA22H could do clean unmodded if you cranked the Crunch master up and used the preamp gain knob as a volume. I really like the depth mod. The SRV style mod I did is really cool if you like cleans. It fills out the low and and adds some sparkle. It's decent. That said, I wouldn't say they need to be modded. The lead circuit in there is very very similar to the SLO, which really set the benchmark for high gain tones. There are loads of mods out there. I could add a voicing switch to the tone stack to change the mid character. That is popular. I also would like to try adding a tone stack and cutting down the channel bleed. Channel bleed seems to be a feature of some soldano designs. The parts in them seem good and the PCB's look to be very similar in layout to what you get in a USA made Soldano
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Ruby tubes are generally branded tubes, they can be anything. I have some Rubys that are Sovtek 12AX7LPS, a JJ ECC83S and a JJ ECC803S and while I was in the store I saw other tubes branded as Ruby too.
I'm really not familiar with Jet City Amplification to be honest but they seem like they're definitely a great buy for the buck, if nothing else.
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Ah! I never spotted that, I do tend to ignore Ruby though. The times when I've ONLY been able to buy Ruby valves in a shop, I generally avoided it because it's been expensive. Like when people try and sell you Mesa 6L6's for stupid money. The ones I have are definitely closest to these chinese jobs. Very similar.
The Jet City stuff is generally licensed Soldano designs though the Picovalve was a THD Univalve affair. The Retro Tubes come from another guy, Doug Roberts. They make a bunch of gadgets but the main amps that have lasted have been the JCA20 (Soldano Atomic 16 kind of thing) and the JCA50/100 (Like a Soldano Hot Rod). The JCA22H is a bit different in that it has the Hot Rod style preamp but the power stage is EL84. It has has a post master loop which im not sure the others do. Soldano currently makes a Hot Rod 25, which i think is the Hot Rod 50 on a lower B+. I think, it even uses the 50watt transformers to a degree and has a choke as standard. It also runs 5881's and not EL84's.
A Soldano Hot Rod+ 100 is probably around the Ģ2K mark now. The JCA stuff is built in the far east with different parts, but I don't think the parts are bad. The resistors are pretty beefy, probably 1watt at least. The filter caps are 105degree rated in place so should probably have a long life. Build quality isn't as high as the US Soldano stuff and the circuits differ slightly, but a few resistor changes can sort you out if you want to be anal. The design quality is better than Bugera and better than a lot of amps up the Ģ900 mark I'd say. I'd rather take one of these over a DSL.
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nice clip :)
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Some MP3's that are a slightly better representation than that video.
For cleans the controls were set...
Clean/Crunch Gain 6
Bass 5.5
Mids 3.5
Treble 5.5
Clean/Crunch Master 2.5
Pres 6
Depth 4
The Bright Switch was switched in and out on the records that used the scoop mod and on the crunch recording.
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Here is a low gain Overdrive Channel recording with the Bright switch for that channel taken in and out, and a straight higher gain recording of that channel (on a guitar tuned to D)
I didn't have the gain over 3 and the master was around 1 for that channel.
Still from the lineout in my hotplate directly into my macbook via the built in audio in, and recorded in Garageband with only LA Convolver and some speaker sims. Greenbacks I think. No other processing. I'm not really into home recording.
But yeah... sounds better through a real cab but these clips are better than the video.