That’s a great quote. So it’s not an ultra-linear design? I really wouldn’t know if the circuit is unusual or not. I’ve just been learning about how certain aspects of design affect the sound. I’ve never built an amp, but am considering it at some point if I can justify getting something I can’t get with modelers. I’m pretty happy with the sounds I can get so far, so it would just be for fun. Digital “fizz” has been addressed with newer oversampling and bit width methods. I consider the last frontier in digital modeling to be realistic amp/OT/speaker cab interaction. The IK Multimedia cab volume feature doesn’t do that. S-Gear has the impedance interaction integrated into the amp models with a two band IR “overlay” EQ in the IR loader. Roland devised a new approach in the GT-1000 they call “AIRD”. Others will surely follow. Resonance dynamics is pretty complicated, but I’m sure it can be mimicked well enough to be convincing. I still like the idea of all analog, and solid state has come a long way. Not sure tubes are necessary anymore, but guitar players will keep them alive for a while.
OT is a Hammond 125ESE. Not even full spectrum, but it works pretty good!
Solid state has come a very long way! Price and complexity. I did amp repair in my home town for a few years, but most solid state stuff is use it till it dies and replace it with the next big thing. Too complex to trace down problems and the “next best thing” cost less than the repair.
Modeling has really come a long way and sounds great! I just still like the warmth of a tube amp. The little HB actually heats my music room when it’s on! 
If you build one, do for yourself. Don’t chase a sound, do it just because you want to and tweak as you go for understanding. Tubes are fun and pretty easy to understand. You’re knowledge is already there.
Hello,
I have some questions pertaining to speaker choice for a similar Jet City amp, the difference being this one is the two channel version of the one in the original post that started this thread. This one is a JCA2212C model with no reverb and a second channel that is higher gain than the first channel – I’m told the first channel is the same circuit as the only channel on the 2112 (a nice name for an album maybe?). I do use verb in the loop sometimes – an Eventide H9 in the loop, a wah, deja vibe, OCD in front of the amp.
The amp had Sovtek power tubes when I bought it, and that’s what is still in it now. I’m an old EL34 guy and never was a fan of the EL84’s, but I have come close to what my ears like to hear with this amp through the right cab – specifically a 4X12 Marshall cab with Celestion greenbacks in it, the next best it ever sounded to my ears was through a 2X12 that has some one off Celestion Relic 30 speakers that they did a production run on for Guitar Center over a decade ago and GC blew them out the door on the cheap, guys either loved them or hated them, I think they sound good with a JCM2000 DSL 50, and they sound good with this Jet City, information on exactly what these things are is scarce to non-existent today – I can say they are not cheap Vintage 30’s because I know a vintage 30 the minute I hear it – like fingernails on a chalk board, again, one of those love them or hate them things, and my guess is when GC was blowing these things out the door the folks who loved them were probably not fans of real Vintage 30’s, and guys who hated them probably like that spikey in your face and cut through the mix thing that the Vintage 30’s do. I’m a fan of the old greenbacks, and the old G12H30’s (that I thought the vintage 30 was supposed to sound like but handle more power – they don’t sound anything alike to my ears at all).
The original speaker in this amp was an Eminence, and it sounds pretty much like it must be a copy of a Celestion Vintage 30 – all mids. Originally I wanted this amp as a head and not a combo, but this one became available on the cheap so I snagged it. After playing it through cabs I almost wish I’d have waited and bought it as just a head. I changed the stock speaker and replaced it with an ET65, and now it seems too scooped. I have an al-cheapo 2X12 Behringer/Bugera cab with some cheesy Jensen copy’s in it, and if this ET65 were 8 ohms I’d put it in this cab paired with something else, but it’s 16 ohm so it will sit on the shelf, get used in something else, or get sold. Just need to know what to try next in the combo amp itself?
Is it possible to get anything in this combo to sound similar (tone wise) to the 4X12 greenback sound using only one 12" speaker mounted in the amp itself? Or should I just take the amp out of the cabinet, build a head cab, and throw the rest in the garbage? I might add here, a friend who has an old JCM800 2X12 combo with original 65 watt Celestions let me play this JCA amp through his speakers/cab and I wasn’t impressed with this either.
Pre amp tubes were some Chinese cheapo’s in v1 and v2 that I changed to Tung Sol’s. V3-5 sockets all have Sovtek 12AX7LPS tubes in them – as it was when I got it. I don’t have a big assortment of tubes to try tube rolling with, but since I have got sound I like through a cab, I’m not sure tube rolling is going to get me where I want to go. I’ve been playing the hell out of this thing as I can’t really use a cranked 50 or 100 watt Marshall 90% of the time I play (nor do I want to haul 4X12 cabs around all the time). I would like to keep using it if I can get it right. I will use a 2X12 cab with it when I can, but that’s not always, so hope to get it to sound good with 1X12 mounted in the stock combo cab the amp is mounted in.
It was asked earlier what kind of music one is playing, so I guess I should throw that in here.
Trower
Jimi
Trower
Zep/Page
Trower
Floyd/Gilmour
Trower
Heart/Nancy, Roger, Howard
Trower
Early ZZ Top/Rev Willie G
Trower
Allman Bros/Duane & Dickie
Trower
AC/DC/Angus
Trower
JP/KK Downing, Glen Tipton
Trower
Alex Lifeson
Trower
Tom Scholz
Trower
Michael Schenker
Perhaps a little more Trower – I can’t seem to leave that $%^& vibe turned off for long! It’s addictive!
I guess this would be considered blues, or classic rock (or both).
How much different is the Retro 30 compared to the ET 65? And more important, how much different is it from a Celestion Vintage 30 – of which I am not a fan at all?
Got any speaker suggestions for this old dude that’s still stuck in 1978?
Thank You 
I’d think the closest thing to a 4x12 cab with early 70’s “Pre Rola” GB’s in a 1x12 cab would be an Invader 50. Closest to a 4x12 with the same era G12H30’s would be a Reaper HP. I just heard this great Reaper HP demo today: https://www.youtube.com/watch?v=tC4GHf2L8K0
My guess is the invader 50 might sound a bit dull in the JCA2212C, but I dunno. I guess you could crank the Presence. My take is although the the Invader 50 is darker, it sounds a bit more metallic. Both have great 4kHz+ chime and are less piercing than a V30.