From 6L6 to EL84

egicar

New member
I’d like to swap the power tubes of my JCA5212r from 6L6 to EL84. I know there are some adapters on the market, but I’d like to do them myself. Any suggestion is greatly appreciated [emoji120]
 
Re: From 6L6 to EL84

To be honest, there's not much point in that. You'd be practically building a new amp when doing that.

There's so many great, budget-friendly options for el84 amps that there's no point in that in my opinion.

If you want less power, 6v6 would be easier and more sensible conversion.
 
Re: From 6L6 to EL84

To be honest, there's not much point in that. You'd be practically building a new amp when doing that.

There's so many great, budget-friendly options for el84 amps that there's no point in that in my opinion.

If you want less power, 6v6 would be easier and more sensible conversion.

Thanks a lot for your tip. I’m searching a class A “VOX” tone. I’ve seen some schematic about this thing: not complicate at all, but there are so few informations on the web.
 
Re: From 6L6 to EL84

I'm not 100% sure, but suspect that class A Vox circuit is way different from 6l6 Jet City.

Many cheap el84 amps out there do use very similar circuits though.

I couldn't find any of these amps on sale to compare prices. But NT series Voxes would be spot on what you're after for very affordable price.
 
Re: From 6L6 to EL84

I'm not 100% sure, but suspect that class A Vox circuit is way different from 6l6 Jet City.

Many cheap el84 amps out there do use very similar circuits though.

I couldn't find any of these amps on sale to compare prices. But NT series Voxes would be spot on what you're after for very affordable price.

Yes, it is different, but it is possible, without internal mod.
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Re: From 6L6 to EL84

If you want to make the change because you enjoy doing electronic mods, I'm of no help. But, if you want to get Vox AC30 tone without major expense ($200), THIS would get you very close. Assuming you can run the head through the speaker cab or have a high quality speaker cab, preferably 4 ohms.
 
Re: From 6L6 to EL84

A speaker swap makes a much bigger difference than a tube swap and is also a lot less invasive. Makes sense monetarily too. If you don't like it, you can sell it. Selling a heavily modified and possibly non functional amp is a losing game. Keep it stock. Modern amps are a massive pain to work on as well so it is a labour intensive job even if you pull it off. At the end all you will have in a best case scenario is an amp that may or may not get close to the sounds you are after, but will be worth next to nothing even though you have spent a lot of time and money on it.
If a speaker swap doesn't get you there, then it is time to sell up and buy a different amp.
What speaker(s) are you using now?
 
Re: From 6L6 to EL84

Used Vox AC15s are like $400. Get a Vox if you want Vox tone.

+1

A Jet City sounds nothing like a Vox; there's a lot more to it than power tubes. The Mesa Mini-Recto uses EL-84s as does my Jet City JCA22H, yet neither of them sound like a Vox. The Jet City amps are loosely based on a Soldano, which is itself based on a JCM800 with a few extra gain stages. The Vox preamp and tone stack are completely different.
 
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From 6L6 to EL84

A speaker swap makes a much bigger difference than a tube swap and is also a lot less invasive. Makes sense monetarily too. If you don't like it, you can sell it. Selling a heavily modified and possibly non functional amp is a losing game. Keep it stock. Modern amps are a massive pain to work on as well so it is a labour intensive job even if you pull it off. At the end all you will have in a best case scenario is an amp that may or may not get close to the sounds you are after, but will be worth next to nothing even though you have spent a lot of time and money on it.
If a speaker swap doesn't get you there, then it is time to sell up and buy a different amp.
What speaker(s) are you using now?

The JCA5212r is a combo, with 2x12 Eminence. I made a 2x10 Jensen p10r cab and I like it very much.
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Re: From 6L6 to EL84

You do understand that an EL84 has a completely different pin layout than a 6L6 and will require new sockets to be installed?

Assuming that the JCA has the sockets mounted direct to the PCB that’ll be some pretty invasive modifications.

I’d look at using an adaptor. Keeps the amp stock and is easier to reverse if you wind up not liking the results.
 
From 6L6 to EL84

You do understand that an EL84 has a completely different pin layout than a 6L6 and will require new sockets to be installed?

Assuming that the JCA has the sockets mounted direct to the PCB that’ll be some pretty invasive modifications.

I’d look at using an adaptor. Keeps the amp stock and is easier to reverse if you wind up not liking the results.

I’m working on an adaptor. I don’t want to mod the stock PCB. I’m near the solution [emoji4], but I’d like to consider others’ ideas about that.
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Re: From 6L6 to EL84

Ok, I know just a little more than enough to be dangerous but still not kill myself so take this for what it costs you. That's an awful lot of voltage to be dropping with Zener diodes. I've read of 20-30 volts being dropped (plate or rail) with higher power zeners that are heatsinked. But a quick look at a couple of the zeners you list and they appear to be 5 watt zeners. Also not sure how you are going to fit everything into a socket adapter, unless you plan on using some sort of external enclosure to house the components and them wire from that to the adapters. Then there is the OT impedance, but I suppose that can be compensated for, at least somewhat, by the amps impedance selector.

Just my weekend electronics hacker observations. But maybe you have it all figured out. Like I mentioned, I just know about enough to not kill myself.
 
Re: From 6L6 to EL84

IMO, amp design affects tone a lot more than power tube selection. If you want Vox tone, get a Vox. An EL84 Lonestar Special sounds nothing like a Vox, yet still uses EL84s.

If it’s just a project, then good luck and have fun! I assume you’ve got the power supply
mods to lower the voltage as well?
 
From 6L6 to EL84

So, thanks a lot to all for your considerations.
I started thinking about adapters like the https://www.yellowjacketstc.com/yellow-jacket/yjs, that they cost me as a used VOX Night Train 15W ...
Of course, I will put all in a box and connect it to the 6L6 sockets, cause it is impossible to me to put all the components in an adapter like Yellow Jacket does.
Considering the 68V zener, I can count on 70 mA of anodic current, that is enough for a 8W class A amplifier stadium.

EDIT: Planet Earth, we have a problem [emoji12]
I just ended to make two prototypes. They work!!! But ... I measured the current through the cathode resistor (360 Ohm) ... It is 270 mA [emoji30]. How to reduce it?

EDIT #2: It was my mistake: there are 27 mA [emoji23]
 
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Re: From 6L6 to EL84

It's still going to sound like a Jet City amplifier, man. And I don't mean that in a bad way. I love Jet City amps.

My Egnater Tweaker still sounds like itself with 6V6 or big ass 6CA7 power tubes. So I'm not really sure why you'd do this.

But I'll tell you this. My Tweaker sounded completely different with all the cabinet combinations I've had. My closed back 2x12 wants to do Marshall tones all day long, cleans are OK I guess. My open back 1x12 sounds tiny for high gain, but it loves overdriven chords and cleans sound BEAUTIFUL and three dimensional. Way more difference than changing the power tubes, man. I can certify that's gonna get you nowhere.

You want your tone to be a bit lighter, "vintage", more open and chimey? Get an open back cabinet with a good speaker for that purpose, and thank us later.
 
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Re: From 6L6 to EL84

It's still going to sound like a Jet City amplifier, man. And I don't mean that in a bad way. I love Jet City amps.

My Egnater Tweaker still sounds like itself with 6V6 or big ass 6CA7 power tubes. So I'm not really sure why you'd do this.

But I'll tell you this. My Tweaker sounded completely different with all the cabinet combinations I've had. My closed back 2x12 wants to do Marshall tones all day long, cleans are OK I guess. My open back 1x12 sounds tiny for high gain, but it loves overdriven chords and cleans sound BEAUTIFUL and three dimensional. Way more difference than changing the power tubes, man. I can certify that's gonna get you nowhere.

You want your tone to be a bit lighter, "vintage", more open and chimey? Get an open back cabinet with a good speaker for that purpose, and thank us later.

If the OP doens't want to get a Vox, a Tweaker on the "AC" tone stack with the right open back cabinet should be at least in the right zip code. I can't seem to get overdriven tones right, but mine will at least approximate a clean Vox tone when set up that way.
 
Re: From 6L6 to EL84

I have a VOX ac4TV, with a GT 12ay7 and a NOS Russian EL84 and I like it very much. I built an open back cab with a 16 Ohm Jensen Alnico p10r and it sounds just as my taste. Now, my 2 prototypes on my JCA work very well and I don’t hear the cross distorsion of a class AB amp. I’m very satisfied of this result [emoji4]
 
Re: From 6L6 to EL84

If you're searching for the class A vox tone even the night train is a bit of a side path. It has a lot of it's own bright, glassy, but kinda fizzy unrefined thing going on and I think most would prefer an ac15 in an A/B. Good cleans but raspy gain to my ears.
They're not that bad but just not that good. And thick mode is a bit of a one trick pony to me.

Your amp with yellow jackets could potentially sound better
 
Re: From 6L6 to EL84

If you're searching for the class A vox tone even the night train is a bit of a side path. It has a lot of it's own bright, glassy, but kinda fizzy unrefined thing going on and I think most would prefer an ac15 in an A/B. Good cleans but raspy gain to my ears.
They're not that bad but just not that good. And thick mode is a bit of a one trick pony to me.

Your amp with yellow jackets could potentially sound better

If AC15's are that cheap Empty Pockets said, then definitely they're better route.

Here used AC15 cost three times the price of NT...
 
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