JET CITY 20 WATT COMBO (single channel)

[mwalluk]

I'm looking everywhere for a detailed version of what V spots, do what....

I know the V1 spot is the driver, the V5 spot is the PI, I believe both V4 and V5 also control reverb, but what does the V2 and V3 spot do? Which one is the tone stack?

Any info would be appreciated.


Also, tube rolling suggestions please....

Option 1: NOS EI, Genalex Gold Lion RI, Tungsol, Tungsol, JJ Ecc803?
Option 2: NOS EI, JJ ECC803, GENALEX Gold Lion RI, EHX, EHX?

RIght now my stable consists of:

NOS EI
Genalex Gold Lion RI
Tungsol (2)
EHX (2)
Ruby (3)
JJ ECC83 (5)
JJ ECC803
Sovtek WB

and maybe something else, don't remember off the top of my head.

ALL TUBES ARE 12AX7! Not planning on buying a different tube type, this is mainly a late night jam/teach my son how to play guitar/spare amp.

[zzmoore]

Re: JET CITY 20 WATT COMBO (single channel)

I would have to look at the shem, but an oversimplification would be.....
Preamp tubes are usually used as voltage amplifiers (gain), recovery for verb and tone stacks to make up for losses from those circuits, and drivers and splitters for phase inverters.
Your V1 is most likely just the first gain stage after the input jack. A lot of your guitar raw signal is amplified in that triode. One reason why so many people say that is the "most important" tube. It is no doubt the most sensitive.
Others will have better/more detailed info.
best

[misterwhizzy]

Re: JET CITY 20 WATT COMBO (single channel)

Which one is the tone stack?

What do you mean by this? I don't think your question makes sense.

In this amp, the tonestack is passive. And I may be speaking above my knowledge level here, so take it with a grain of salt. In the head, there are three voltage gain stages before the cathode follower, which takes that voltage and turns it into a lower voltage, higher current signal. This drives through the tonestack, which is a series of three filters, into the PI.

I remembered seeing the schematic for the combo at one point, and I think V3 and V4 were send and receive for the reverb, but now I can't remember, and I don't feel like trying to find the schematic again.

No tube IS the tone stack, which is why I don't understand your question.

[zzmoore]

Re: JET CITY 20 WATT COMBO (single channel)

I think he is asking which Tube/Triode the tone stack is connected to.
Probably wants to know which 2 triodes the stack is associated with.
Not sure about a schem for an amp like this that is currently in production, but that would sure help.
best

[Wattage]

Re: JET CITY 20 WATT COMBO (single channel)

Man the PT's make a huge difference in these. Check out the Tung-Sols and lost the weird edge-y sound they have out of the box.

[mwalluk]

Re: JET CITY 20 WATT COMBO (single channel)

I think he is asking which Tube/Triode the tone stack is connected to.
Probably wants to know which 2 triodes the stack is associated with.
Not sure about a schem for an amp like this that is currently in production, but that would sure help.
best

That's what I was referring to. For instance in my vht v1 and v2 are my main gain stages with v2 adding extra when more switch is engaged, v3 is gain and tone, v4 is pi

[ken361]

Re: JET CITY 20 WATT COMBO (single channel)

from jet city
V1 12AX7 - Input and 1st gain stage (closest to the input jack)
V2 12AX7 - 2nd gain stage/ 3rd amp stage (also provides drive to
reverb tube)
V3 12AX7 - Reverb wet and dry mix + drives tone control
V4 12AX7 - phase Inverter
V5 EL84 - Power Tube
V6 EL84 - Power Tube
V7 12AX7 – 12 AX7 drive and return

[mwalluk]

Re: JET CITY 20 WATT COMBO (single channel)

from jet city
V1 12AX7 - Input and 1st gain stage (closest to the input jack)
V2 12AX7 - 2nd gain stage/ 3rd amp stage (also provides drive to
reverb tube)
V3 12AX7 - Reverb wet and dry mix + drives tone control
V4 12AX7 - phase Inverter
V5 EL84 - Power Tube
V6 EL84 - Power Tube
V7 12AX7 – 12 AX7 drive and return

Hmmm. That's interesting layout. Thanks that's exactly what I was looking for.

I thought the PI was always the last tube.

Any special tubes should go in V7?

[ken361]

Re: JET CITY 20 WATT COMBO (single channel)

I would think that the 7 would be the PI makes more sense to me since its closer to the power tubes. He might have it wrong, that tube does get real hot real quick so it could be. You ask Doug at jet city, the guy I got this from was a rep.