Guitar Gear Forum

As of right now this is the only pic I have. I also painted the back grill white and am waiting on white chickenhead knobs.
Ive been curious about the debate using KT66's, I'll have to read up a bit more.

GRIMESPACE wrote:The following list of effects found to be compatible with the JCA effects loop was compiled by GuitarBilly74. I'll continue to update / modify the list as needed.

Delay:
Hardwire Delay
TC Nova Delay
TC Nova Repeater Delay
TC Flashback
Boss DD-20
Tech 21 D.L.A/boost
Eventide Time Factor

So will any other delay have problems when run through the JCA effects loop? What about a JCA20HV head? I tried a Mooer Reecho through a JCA20HV and when the pedal was engaged, the overall volume dropped significantly. I believe it's a Mojo Tone F/X loop and can be modded by adding send/return level adjustments.

Hi Guys, FINALLY got my 100HDM yesterday after months of waiting impatiently, reading all the posts here only made the waiting worse !

HOWEVER ... When finally I plugged in and cranked it up I was not very impressed, actually very disappointed. It sounded nothing like the clips from Fast Red Pony Car and any other good clips I've heard, despite the same settings, even went as far as using the Hardwire CM-2 ( which did help a lot ). This was through a Marshall Vintage Modern 4 X 12 which is killer with my other amps.

On all 3 guitars I have, the HDM was just ok. It almost gave my humbuckers ( particularly my Bare Knuckles Steve Stevens ) sound like I had the neck single coil pickup on as well, very weird. Also whilst I'm not a huge gain head, my 100 HDM does not seem to have a lot of gain, even when maxed ( very little difference between 7 and maxed )

So maybe one or more of the preamp tubes aint doing its thing or something, or is this actually the way its meant to be ?

I bought a VHT Special 6 Ultra just for a laugh while I was waiting for the HDM to come back in to stock, and it pisses all over the HDM !! ... obviously not in volume but just tons of great tones, it even has more gain

Any ideas or have I got a dud ?

BlackCollarGuitar wrote:As of right now this is the only pic I have. I also painted the back grill white and am waiting on white chickenhead knobs.
Ive been curious about the debate using KT66's, I'll have to read up a bit more.

A lot of guys and gals use the JJ KT66s with no problems. I believe they have done so without internal modification. You MAY want to bump the screen grids up to 1k5 or so, but most people just seem to plug and play.

The Tung Sol KT66 also looks like it should work, as a lot of the electrical data shows they have a LOT in common with the standard 6L6, but with a beefier internal structure and larger glass envelope. The heaters draw that same amount of current as a 6L6, which I consider to be the most important factor to keep the amp itself happy. Like I stated above, you may want to bump the SGRs up a little to keep the screens on the KTs happier, but the Tung Sols look, on paper, like they are the most compatible drop-in.

murph100 wrote:Hi Guys, FINALLY got my 100HDM yesterday after months of waiting impatiently, reading all the posts here only made the waiting worse !

HOWEVER ... When finally I plugged in and cranked it up I was not very impressed, actually very disappointed. It sounded nothing like the clips from Fast Red Pony Car and any other good clips I've heard, despite the same settings, even went as far as using the Hardwire CM-2 ( which did help a lot ). This was through a Marshall Vintage Modern 4 X 12 which is killer with my other amps.

On all 3 guitars I have, the HDM was just ok. It almost gave my humbuckers ( particularly my Bare Knuckles Steve Stevens ) sound like I had the neck single coil pickup on as well, very weird. Also whilst I'm not a huge gain head, my 100 HDM does not seem to have a lot of gain, even when maxed ( very little difference between 7 and maxed )

So maybe one or more of the preamp tubes aint doing its thing or something, or is this actually the way its meant to be ?

I bought a VHT Special 6 Ultra just for a laugh while I was waiting for the HDM to come back in to stock, and it pisses all over the HDM !! ... obviously not in volume but just tons of great tones, it even has more gain

Any ideas or have I got a dud ?

What channel/settings are you using? What tubes are in your HDM. The stock tubes that Jet City uses are more of a cost-effective choice, not the best for tone. If you have some spare tubes, drop them in the HDM. I severely dislike the stock tubes. Also, they bias those amps very cold, so getting a proper setting even on the stock tubes helps them out a ton.

And FWIW, if you can max out the gain and you don't get a lot of annoying feedback, then there must be a bum tube or something wrong in there.

....and I'm very interested in how you like the Steve Stevens pickups. I have been looking at those myself.

Cheers Jay,


I've been using both channels, played around with it for about 3 hours, even duplicated some settings from the various YouTube clips just to make sure, but still pretty meh.

The preamp tubes are no name with 12AX7B China on them, and the power tubes are labeled 'Electron Tube' 6L6WGH Made in China.

I'll definitely order some decent tubes and try them out.

When the gain is maxed on the Lead Channel I dont get any feedback, in fact nothing much happens from 3 O'Clock to max, kind of like a gain stage aint kicking in. I'll take it to a local amp tech for a quick look.

RE the Steve Stevens pup, yeah really nice, very good string definition and not overly hot either, a lot of other guys swear by the Mule & Warpig so I might try those at some stage..

If you can max out the gain on the lead channel, then I bet one of the preamp tubes has gone bad, or maybe the amp isn't switching properly. Does the tone/gain change at all when switching from Crunch to OD? How loud are you playing?

You don't necessarily need to order a whole compliment of tubes just yet. While I do think the power tubes should be changed at some point soon because they don't seem to be matched well from the factory and I think there are better choices, let's figure out why the amp might not be behaving to your expectations.

If you have any spare 12AX7s, or if the VHT has any in it, try swapping out one tube at a time in the HDM with a known good tube so you can eliminate what might possibly be just a bad preamp tube.

The channels do change alright, I reckon its either probably a crappy 12AX7 ... now why didn't I think about swapping in the good ones from the VHT

As for volume, I've played it at every volume all the way to max ( paint is still just about on one wall ) and still no improvement.

Funny thing is though, the crunch channel aint bad, and when clean boosted with the CM2 its pretty neat ... but still not a patch on the cheap assed VHT

So next up is the tube swap, failing that its off to the Amp Tech, I'll keep you posted.

murph100 wrote:The channels do change alright, I reckon its either probably a crappy 12AX7 ... now why didn't I think about swapping in the good ones from the VHT

As for volume, I've played it at every volume all the way to max ( paint is still just about on one wall ) and still no improvement.

Funny thing is though, the crunch channel aint bad, and when clean boosted with the CM2 its pretty neat ... but still not a patch on the cheap assed VHT

So next up is the tube swap, failing that its off to the Amp Tech, I'll keep you posted.

I really like the Crunch channel boosted. On the stock 22H, I preferred the boosted crunch channel over the lead channel. Different story after I modded the lead channel, lol.

Anywho, try some preamp tubes and get a better bias setting on the power tubes and see how that works.

Just a quick update, I put in the 12AX7s from the VHT into HDM V1 & V2 ( V1 is over the input jack innit ? ) and things improved a lot ! Still not mega, and still no crazy feedback with the lead channel gain maxed but enough to convince me to order a set of 12AX7s. I was gonna get 4 Tung-Sol 12AX7s and 4 JJ 12AX7s so I could try out a few combinations and have some spares for both amps. Any opinions on these tubes ?

One other thing I noticed, which might be of interest to you Jay, is that the Bare Knuckles Steve Stevens sound sh1t through the HDM The Gibson pups and the PRS Chainsaw pups sound good but the Steve Stevens completely sucks ass on it, when it was incredible on the VHT. Might have something to do with the 500k vol pot I have in it, I'll experiment with it over the weekend and change the height and pot to see if that helps it.

Its times like this when I feel like shooting myself for selling my Boogie Studio Preamp way back in the day, best sound ever ! Sold it to upgrade to a Quad which was complete rubbish by comparison

I have actually found the Mullards and JJs so sound best in the JCAs. And I have been using some Gibson Burstbuckers for most of my demos, and the pow output PAF style pickups are really good!

lol regrets? I sold my MKIII a while back and am still kicking myself.

Cheers Jay, I'll add a couple of Mullards to the shopping list .

What mods have you done to your JCA ? I've been through all the pages here but it would be cool to know which ones made the most difference.

BTW nice move with the MKIII, glad I'm not alone in outstanding decisions

On my JCA20H I have done some tube rolling, changed/added an RC network and not much else yet. On a friends JCA50H, I added a new PT because the old one blew, the SLO mod and lowered the FX loop level.

On the same guy's JCA22H, I revamped a lot of the preamp to be more like a wickedly hotrodded Marshall. The 22H in stock for to be very wooly and too thick. After the mods, it's much tighter, brighter and meaner.

Looks like the jca2212 - the combo jca22 - is the musicians friend stupid deal of the day today for $300. That's a lot of amp for 300 bucks.

mjtripper wrote:Looks like the jca2212 - the combo jca22 - is the musicians friend stupid deal of the day today for $300. That's a lot of amp for 300 bucks.

NAD: Took delivery on this deal today. UPS actually delivered it in one piece. After 5min 'confirm it works' test: easy to bond with the crunch esp with treb & presence very low - not sure yet about the OD. Plan to spend some quality time with it this weekend.

edit: just saw new announced low price for the 50w Combo $399 - available at jet city website. good price there.

extollo wrote:

mjtripper wrote:Looks like the jca2212 - the combo jca22 - is the musicians friend stupid deal of the day today for $300. That's a lot of amp for 300 bucks.

NAD: Took delivery on this deal today. UPS actually delivered it in one piece. After 5min 'confirm it works' test: easy to bond with the crunch esp with treb & presence very low - not sure yet about the OD. Plan to spend some quality time with it this weekend.

edit: just saw new announced low price for the 50w Combo $399 - available at jet city website. good price there.

Congrats & welcome to the club. Pretty killer deal you got there.

Tubes, Bias, and Depth control make a huge difference.

What speakers are you running?

You know, honestly, I don't think I'm going to install the depth mod on my 20H. With the right tube combination, good settings and my beefy Les Paul, it packs plenty of punch. I'll probably just mod the NFB network to loosen things up a bit, but no drilling for this one. Mullard preamps make a big difference. DEFINITELY fill out the sound.

Might have to give the Mullard a try on the next go-round. Planning to put in 6L6WXT+ in the power section, too.

Jay - have you tried a 5751 in V1 or PI yet? I really want to bring the gain down, and am wondering if that'd be better than doing any more mods.

BlackCollarGuitar wrote:As of right now this is the only pic I have. I also painted the back grill white and am waiting on white chickenhead knobs.
Ive been curious about the debate using KT66's, I'll have to read up a bit more.

BlackCollarGuitar wrote:Hey guys, another new member here. Been searching around for mod ideas on the Jet City amps. If anyone has any suggestions on what to try next that would be awesome

I got a JCA 50H, I have done some custom cosmetic work myself. I run the head through two peavey 212 cabs with Celestion EK-85's, which ive read are very similar to V30's but more bass?
On order I have four JJ 12AX7's, not sure yet to order a fifth, use the chinese 12ax7 somewhere or another brand.
Also waiting on Genelax Gold Lion KT66's for the power section.

If anyones interested I can post a comparison video of stock vs. these tubes once I receive them!

Looks really good! I have the same cab. Are they 212 MC or 212 MS? If they are MC, the speakers are K-85's also known as K100's. NOTHING like V30. Much higher power handling and generally heavier sounding. However, I keep hearing great things about JCA and V30 so i am dying to try some.

OK finally got a chance to let rip with full set of new tubes ... WOW ! What a difference !! Much more gain, but also way more dynamic, cleans up better using vol and that singing lead tone is there in bucket loads, LOVE IT !!

I retubed with JJ 6L6, Tungsol 12AX7 & JJ 12 AX7, all from Karl at www.karltone.co.uk who was really helpful and very efficient . He had no Mullards in stock so I'll get that at a later stage.

So now I'm really digging the amp, especially the Crunch channel with a clean boost, absolute killer tone ! I now see why most guys here and elsewhere tend to use the Crunch for everything, so what makes the Crunch channel so much better than the OD channel, and what are the best mods to make the lead channel better ?

GRIMESPACE wrote:Tubes, Bias, and Depth control make a huge difference.
What speakers are you running?

stock emi that came with the combo. not seeing a need to change it in the near term. i'll likely do the depth mod & tube swaps though. i was going to do the clean/crunch switch, but after spending some time with the amp i dont see a value in doing that unless it is accompanied with some voicing changes as well. not a priority.

murph100 wrote: I now see why most guys here and elsewhere tend to use the Crunch for everything, so what makes the Crunch channel so much better than the OD channel, and what are the best mods to make the lead channel better ?

I'm hearing an odd mid overtone in the OD channel - honky sounding like an overdriven 6" speaker. maybe better tubes will clear that up.

I'm feeling the same way about the channels - i'll be using crunch & will be looking tinker with the OD channel.

extollo wrote:

GRIMESPACE wrote:Tubes, Bias, and Depth control make a huge difference.
What speakers are you running?

stock emi that came with the combo. not seeing a need to change it in the near term. i'll likely do the depth mod & tube swaps though. i was going to do the clean/crunch switch, but after spending some time with the amp i dont see a value in doing that unless it is accompanied with some voicing changes as well. not a priority.

Didn't realize you got the combo - that was $300?!?!? Great score! I have heard that the Eminence speaker is a great match with the JCA stuff - I believe Soldano uses them in his SLO cabinet as well, so that's gotta count for something, right?

I personally wouldn't kill myself over the clean/crunch switch, especially if you're able to get what you need out of the stock channels. While I've been happy with the clean switch on mine, it's not very versatile - it's not footswitchable (can't use it like a 3-channel amp during performance), there's a HUGE volume jump when turning it off / on, and it sounds HORRIBLE (imho, of course ) when trying to gain it back up with a boost, OD, or dist. I think, for me, I need to learn to use the volume control on my guitar as the 3rd channel if I want to do clean / crunch / burn when performing with this amp.

Besides the depth mod, I get the most use out of the voicing switch (go back a few pages for LOTS of discussion on that), and I highly recommend checking into that. It makes a huge difference in the amount of 'give' that the amp has - loosens it up and sounds killer for lead stuff. I've got my on a panel switch that lets me go back to stock (much tighter, especially when doing heavier palm-muting stuff). If I had my way, I'd have a foot-switchable lead boost that'd let me punch the volume up and kick that voicing switch on, but I'll probably never get around to that. For now, I generally just leave that switch on.

murph100 wrote:OK finally got a chance to let rip with full set of new tubes ... WOW ! What a difference !! Much more gain, but also way more dynamic, cleans up better using vol and that singing lead tone is there in bucket loads, LOVE IT !!

I retubed with JJ 6L6, Tungsol 12AX7 & JJ 12 AX7, all from Karl at http://www.karltone.co.uk who was really helpful and very efficient . He had no Mullards in stock so I'll get that at a later stage.

So now I'm really digging the amp, especially the Crunch channel with a clean boost, absolute killer tone ! I now see why most guys here and elsewhere tend to use the Crunch for everything, so what makes the Crunch channel so much better than the OD channel, and what are the best mods to make the lead channel better ?

Tubes really do make a huge difference. I actually think it's a good thing that JCA ships with cheaper tubes. It seems like so many new amp buyers start changing tubes right off the bat anyways - why pay extra $$$ for a specific tube when they're gonna get changed out anyways? Glad to hear it worked out for you.

A lot of people have been talking very positively about the SLO mod, which (I think) affects both channels. I'm sure Jay or one of the others more experienced will chime in on this to give you some direction - what are you looking for?

Can't wait to spend time in my new studio with the OD channel and my boost / OD pedals to see what everyone keeps talking about...

GRIMESPACE wrote:Might have to give the Mullard a try on the next go-round. Planning to put in 6L6WXT+ in the power section, too.

Jay - have you tried a 5751 in V1 or PI yet? I really want to bring the gain down, and am wondering if that'd be better than doing any more mods.

6L6WXT+ in my opinion (take it for what it is, an OPINION) is terrible. I have not liked those in any amp I have used them in. I would honestly stick with JJs or Rubys, or try out some of the KT66s. The Tung Sol seems like a pretty simple drop-in. The heaters are the same as a 6L6, which is what I look for most when checking compatibility. The SGRs may want to be changed at some point, but they should be fine with the stockers for a while.

I got to try a few tubes from the Tube Rolling thread I had started a while back, and the GE 5751 was one of them. I tried it in the PI of my bud's 22H and and I REALLY liked the result. Mullard or Voskhod in V1, JJs in V2-V4, 5751 in PI. I know JJ and Sovtek make 5751s, but I hear NOS is the way to go. The JJ 803s is another of my favorites in the PI and the 12AU7/ECC82s is really nice. Another tube to use to bring the gain down would be the JJ 12DW7 in V2. If you feel adventurous, you could change the second voltage divider from 470k/1M (some amps have 220/470k) to 470k/220k to lower the gain going into the 3rd stage.

extollo wrote:

GRIMESPACE wrote:Tubes, Bias, and Depth control make a huge difference.
What speakers are you running?

stock emi that came with the combo. not seeing a need to change it in the near term. i'll likely do the depth mod & tube swaps though. i was going to do the clean/crunch switch, but after spending some time with the amp i dont see a value in doing that unless it is accompanied with some voicing changes as well. not a priority.

murph100 wrote: I now see why most guys here and elsewhere tend to use the Crunch for everything, so what makes the Crunch channel so much better than the OD channel, and what are the best mods to make the lead channel better ?

I'm hearing an odd mid overtone in the OD channel - honky sounding like an overdriven 6" speaker. maybe better tubes will clear that up.

I'm feeling the same way about the channels - i'll be using crunch & will be looking tinker with the OD channel.

Tubes will help some of the honk. The SLO mod will clear things up quite a bit, but bump up the gain. Lowering the value of some of the coupling caps and slightly increasing the peakers will add clarity, or if you want to get nuts, I'll go over a huge (but easy) mod to really add some scream. Think very hotrodded Marshall. Otherwise, a lot of dudes (myself included) find the 22H to be a bit too wooly in stock form.

Jay wrote:
Tubes will help some of the honk. The SLO mod will clear things up quite a bit, but bump up the gain. Lowering the value of some of the coupling caps and slightly increasing the peakers will add clarity, or if you want to get nuts, I'll go over a huge (but easy) mod to really add some scream. Think very hotrodded Marshall. Otherwise, a lot of dudes (myself included) find the 22H to be a bit too wooly in stock form.

i assume you're talking about the mods discussed starting http://www.guitarampboard.com/forum/viewtopic.php?f=5&t=1615&start=500#p118460