Members Motocooney Posted March 7, 2013 Members Share Posted March 7, 2013 Just realized u didn't ask about modding it lol. Sorry. Link to comment Share on other sites More sharing options...
Members Promit Posted March 7, 2013 Members Share Posted March 7, 2013 I do want to mod it, but the schematics on this thread seem to be for the 50. A nice roundup of what mods are available for the 22 and how to do them would be nice. Link to comment Share on other sites More sharing options...
Members Motocooney Posted March 7, 2013 Members Share Posted March 7, 2013 Yea forgot to mention like ^^^^^this guy said, rebiasing even the stock power tubes made a huge difference:)As far as mods, look at the first page of this thread. I would print the schematics for the 50 and the 22. If u look, you'll see that the layout between the 2 is basically the same. The component #s are different. Just figure it out. Or just read the last 10 of so pages of this thread lol. Link to comment Share on other sites More sharing options...
Members käsebrot Posted March 7, 2013 Members Share Posted March 7, 2013 The tube layout on 22H should be: V1: 1st gain stage c and o channelV2: 2nd and 3rd gain stage o channelV3: 2nd gain stage c and 4th gain stage o channelV4: EQ and loopV5: Phase inverter So as you see, V2 is only for the overdrive channel.An exchange of the power tubes to JJs makes a big difference, I highly recommend that. And bias it at 16 to 20mA (just do that by listening and take a control with the dmm).The circuit of the 22H is a little bit different from the 50H/100H, especially the overdrive section. If you like the sound overall, there is no need to do a lot of mods. What I would do, to tame the flubbyness and this wooly sound a little bit:- lower C2 to 4,7nF- swap out R9- swap out C10, if that's too fizzy, than try the stock 1nF in series with 220k up to 680k (lower R = less treble)- change the slope resistor R 26 to 39kAnd do the depth mod, if you need more bottom end. What also could help to get a better sound is to change all the non-electronic capacitators. I recommend Sozo for all values between 1nf and 1uF, for the 1uF I like the SCR Solen Fast very much and for the lower values up to 1nF I recommend high voltage ceramic caps. Therefore you could also use Silver Micas, but I wouldn't do that because they sound very shrill and have a "ringing treble", also it's possible that you will get problems with dc leakage. Hope that helps. Link to comment Share on other sites More sharing options...
Members Motocooney Posted March 10, 2013 Members Share Posted March 10, 2013 R24 is the slope on the 22h.Just get a simple single throw toggle and run a resistor of your choice parallel to the slope resistor. The values are up to you. If you run a 220k parallel to the stock 47k you will have 39k when you switch. Link to comment Share on other sites More sharing options...
Members käsebrot Posted March 10, 2013 Members Share Posted March 10, 2013 Motocooney wrote: R24 is the slope on the 22h. Just get a simple single throw toggle and run a resistor of your choice parallel to the slope resistor. The values are up to you. If you run a 220k parallel to the stock 47k you will have 39k when you switch. That's not right.The slope resistor on the 22H is R26.And I would use an on/on switch, a 33k on the on and a 47k on the other side. And just two wires to the lugs on the pcb. Very easy.But why switchable slope? The difference is not that much - as I said, I would use a 39k. Just this. But it's a matter of personal taste.If you want to make things switchable, try this with the nfb resistor. 8 or 10k more and you will get a much tighter sound. Link to comment Share on other sites More sharing options...
Members Borderline11 Posted March 14, 2013 Members Share Posted March 14, 2013 Wow! I have several pages of discussion to catch up on. How exciting! Here's what I've been up to.... Basic SLO mod - A video overview. And here are some sound bytes....Just some noodling to illustrate the amp sound... 3 rough covers to show the OD channel gain sounds at 2, 4, and 5.5 As you can tell, I'm as new to modding as I am playing guitar! Ha! How about you experienced players? Let's hear what sounds you are getting out of the JCAs! I'm just using a camcorder and windows live movie maker (freeware). Give a shout out with your own videos! Link to comment Share on other sites More sharing options...
Members Soulcrusher_X Posted March 14, 2013 Members Share Posted March 14, 2013 Were you using the V30 Tourmaster cab? Good tones man. Link to comment Share on other sites More sharing options...
Members Soulcrusher_X Posted March 14, 2013 Members Share Posted March 14, 2013 Actually, I want to hear what that Pearly Gates sounds like with the 22. Link to comment Share on other sites More sharing options...
Members Meelocheck Posted March 20, 2013 Members Share Posted March 20, 2013 Hey guys, first post - happy to be here. I have been lurking since I bought my first JCA22H a few weeks ago. It showed up damaged and never even powered on properly so it went back. I ordered a new one which arrived today and all I can say is this thing is a small beast. Going to take a little getting used to - I came from an Ibanez Toneblaster 100H to this and it is my first ever tube amp. But, I agree with most of the guys here who say it can get a little fizzy and the lower end can get a little muddy - that is pretty spot on. I am fairly confident in my soldering ability and in doing some of the mods mentioned here. I already grabbed the components to do the depth mod so that will be the first thing I do. My only question on that is this: I found a knob that is identical to the ones already on the amp except that it is roughly 1/2 the size. It would fit perfectly between the stand by switch and the presence knob. Is there a problem with making that wire longer so I can mount the pot in the front of the chassis? I don't get much, if any, static or buzz, or humming out of the amp now and I certainly don't want to create any. Just curious... Now, to bias or not to bias. I have a decent meter and know how to use it, for the most part. Biasing the amp seems pretty straight forward, fairly easy and cheap! I am not in a band and I only play for my own amusement and enjoyment so making this amp sound better for as little investment as possible is my goal. It seems like people go both ways on the topic of biasing - I am still up in the air on that one myself since I have never done it and don't know if it will improve it for sure. I know a bunch of guys are swapping out tubes and that is something I don't want to get into - mainly because of the extra money involved. The depth mod is cheap - the components cost me 8$ while swapping tubes can run into the 100+$ range...Yea, no thanks, it just doesn't mean that much ot me...yet! If I can get a little more oomph out of this thing by biasing what I have I may give it a go. Thoughts? Anywho, I'd like to thank you guys for the work all of you have done in this thread. It makes modding for guys like me a lot easier and I appreciate it. I only hope that I can learn a thing or two and then have something of my own to add to this thread - this place is a wealth of knowledge and I am glad to be a part of it. Peace. Link to comment Share on other sites More sharing options...
Members Jase01 Posted March 21, 2013 Members Share Posted March 21, 2013 Hey guys, would this work as a slope mod extension type of thing. So you could have 3 or 4 different choices?? Link to comment Share on other sites More sharing options...
Members Motocooney Posted March 26, 2013 Members Share Posted March 26, 2013 Hey guyshow can i add more low end to my 100?does the value of the depth pot affect how much low end i get from the resonance control?What components affect bass responseMy 100h just seems a little thin to meCathode bypass caps? Link to comment Share on other sites More sharing options...
Members ewizard Posted March 26, 2013 Members Share Posted March 26, 2013 After utilizing the depth mod in standard form, I found that I have more bass than is needed now. I used a 1 meg as suggested, but it's been said a 250K will really make the MOJO happen quicker. But I stress that I have more than I need even with the standard circuit. I'm looking to find a way to get less highs, not more lows. The high end sizzle is what bothers me. I think I will be adding some small PF rated caps to the plate resistors? The current sizzle cap ( C12 ) is notr doing the job. Link to comment Share on other sites More sharing options...
Members Motocooney Posted March 26, 2013 Members Share Posted March 26, 2013 Hmmm I'm using a 250k pot and I want more low end. Maybe I should try a 1 meg? Lol.I found messing with the treble cap( lowering it) got rid of the piercing highs. Link to comment Share on other sites More sharing options...
Members Soulcrusher_X Posted March 26, 2013 Members Share Posted March 26, 2013 To increase some low end, you could bump the coupling caps for the power tubes up to 47n like on the SLO. Also, try increasing R5 from 10k to 15k or 22k. You should get a bump in the low end. To get rid of the fizzies, some small pF caps on the anodes of the PI will work. Even increasing the screen resistors on the power tubes from 470r to 1k will help with some fizz. Link to comment Share on other sites More sharing options...
Members Motocooney Posted March 27, 2013 Members Share Posted March 27, 2013 I increased the depth pot cap to 5,6nf and moved the nfb wire to the 8 ohm tap. Seems just right. For some reason, the depth control is much more effective on my 22h than the 100h. Link to comment Share on other sites More sharing options...
Members sevenmusic Posted March 27, 2013 Members Share Posted March 27, 2013 For me, the depth mod is more effective on my JCA100H than on my 5212RC.JCA 100H: NFB wire to the 4 ohm tapJCA 5212RC: NFB wire to the 8 ohm tapIs this perhaps the reason?... Link to comment Share on other sites More sharing options...
Members Motocooney Posted March 28, 2013 Members Share Posted March 28, 2013 For the cap on the Phase inverter, do I put it across pins 1 and 6. Or 3 and 8? Link to comment Share on other sites More sharing options...
Members ewizard Posted March 28, 2013 Members Share Posted March 28, 2013 No, you put it over the top of the plate resistor. It is parallel to the resistor. It is weird how it works, but signal flows from the cathode to the anode. The anode is the plate. The high voltage is supplied to the plate, but the current from the cathode is what drives the signal out the plate. This is why plate driven stages are usually high impedance and cathode driven stages are low impedance. The classic cathode follower, or cathode followed tone stacks are what is popular for many amps. The cathode has a large current flow and can push through a tone stack with little loss, where as a plate driven tone stack has a significant insertion loss. The use of inter stage attenuation allows for a lot of tweaking before a tone stack and then of souse the tone stack can do it's job at the end. Conversely a plate driven stack is done early in the signal to reduce insertion loss and shape the sound early, but still allow for tone shaping in the other stages. The insertion loss is what defines how well a tone stack will effect the tone. The plate driven TS ( tone stack ) will have more effect over the frequencies it can control, but it will have lower level over all. The cathode driven tone stake has less effect over the control frequencies, but will push through harder ( more volume ) to the next stage.This is why you find most cathode driven tone stacks towards the end of the drive stages. It shapes the sound towards the end of the flow and allows enough push to drive the PI ( phase inverter ) and ouput tubes into distortion as well. You will almost always find a make up stage after a plate driven tone stack to make up for the lost level. Back on point, the cap that goes over the plate resistor actually shunts high frequencies out of the signal path. It basically treats the positive voltage supply as a ground. It seems opposite, but makes sense once you see how the amp really works. This link: http://www.ampbooks.com/home/amplifier-calculators/plate-bypass-capacitor/ actually explains it better and uses an SLO as an example. Link to comment Share on other sites More sharing options...
Members Motocooney Posted March 28, 2013 Members Share Posted March 28, 2013 Okay thanks man!This is the plate resistor on v5 right?The phase inverter tube....In that link they are using a cap on on the plate resistor of the 3rd gain stage.Confused. Link to comment Share on other sites More sharing options...
Members Soulcrusher_X Posted March 28, 2013 Members Share Posted March 28, 2013 If you are talking about the fizz cap, it's pins 1 and 6. Link to comment Share on other sites More sharing options...
Members bfguitarist1 Posted April 3, 2013 Members Share Posted April 3, 2013 I need some help I have the Jca100h. I bought it used played it with no issues for about a month. Tonight at rehersal I fired everything up asusual and after playing for a minute I lost all sound. I came back only to cut out again and then a few more time until it quit completly. If i turn the volume up I have noise coming through the speakers but nothing from my guitar...There is no burnt electronic smell at all....Any ideas what this could be? ThanksSteve Link to comment Share on other sites More sharing options...
Members käsebrot Posted April 3, 2013 Members Share Posted April 3, 2013 @ bfguitarist1: It's not possible to say exactly what's the matter. Could be the tubes. If you have a chance to replace them, check this out. If it's only one bad preamp tube, so you could try playing in crunch mode and changing positions. If the sound comes alive - the bad tube would be in V2 (because V2 is only for overdrive).You could also change the positions of the Power Tubes. Just try it with the two inner tubes - if they work, you will have half power (this should work on the 100H as I think). If you have mismatched the impedances of the amp and the cab, maybe you damaged the output transformer. I don't know. Check the tubes - and if there's nothing wrong, you have to bring the amp to an amp tech. Link to comment Share on other sites More sharing options...
Members ewizard Posted April 3, 2013 Members Share Posted April 3, 2013 could be a bad tube, or perhaps a bad socket connection at the tube. swap out the preamp tubes with a known good one. And while your in there look at the tube sockets for a burnt look. They could be arcing. If that isn't it, you should be able to see if a resistor has been burned? Link to comment Share on other sites More sharing options...
Members kaoslord Posted April 3, 2013 Members Share Posted April 3, 2013 are there any 7-string players ?just wanted to know how your JetCity sounds with a 7th.I own a JCA100 and I find that the beast has too much "ompf" and low end in the OD channel (clean channel is just perfect). No matter which tube you put in, (even tried a 12ay7 in V1: gorgeous cleans and sweet crunchs), but when the OD is engaged, power chords and palm mutes just don't sound OK... the distortion is brutal but It lacks presence and tightness.Looking for an easy mod to cure the muddy beast.Thanks, Link to comment Share on other sites More sharing options...
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