Rocker30 preamp section scheme and tubes choice

[jerem37]

Hello everybody,

i have a RK30H with chinese 12AX7 preamp tubes (like a lot of RK30 owners).
I would like to change it for better ones to improve the tonal response of my amp (that is already good, but can be performed).
Does someone (users or Orange webmasters) have the scheme of the preamp tubes positions and its fonctions for each one? because it's not explain in the owner manal...
I really need that to understand how the preamp tubes works and then make the best choices.
Thanks a lot.

[a.hun]

Hi there.

See labelled pic and description here:
http://forum.orangeamps.com/viewtopic.p ... c&start=15





Andy.

[jerem37]

Hi Andy.
That was exactly what i searched.
Thank you very much

[jerem37]

The preamp valves are labelled V1, V2 and V3 in this pic:



(Apologies to notagain for borrowing the pic...) Smile

(Sorry also for going back to basics here if you know preamp valves 1.01 already. Some reading this may not though...)

Each preamp valve has two separate halves and is effectively two valves in one bottle. They are totally separate and can be working in totally different parts of an amps circuitry.

The 'Natural' channel just uses one half of the V1 valve for its gain stage.

The 'Dirty' channel uses the other half of V1 and both halves of V2 for its three gain stages.

V3 is called the 'phase inverter' (PI) valve. Technically it is really more part of the power amp than the preamp. Signals from both channels go via it to the power stage.

So changing V3 (the PI) will affect the sound of the whole amp. (Want the whole amp brighter for example? A brighter sounding valve there will do it.) Changing V2 will only affect the sound of the dirty channel. Changing V1 will affect both natural and dirty channels, but differently from V3 as V1 has gain stages.

Pull V2 and the 'Natural' channel still works fine but you'll get nothing through the dirty channel. Pull either V1 or V3 and (for different reasons) you'll get no signal through either channel.

Knowing that upinflames, if you are basically happy with the sound of the dirty channel you only want to swap out V1. (You're inevitably going to change the sound / feel of both channels, but thats life. If it changes the dirty channel tone / gain some you can alway reset the controls on that channel a bit to compensate.)

Hi Andy and everybody,

does it means that it's impossible to have more headroom and power/volume (by staying 100% clean) on the Natural (maybe by putting a 5751 in V1) without making the dirty gain starting "further" that it already does?
Because my problem is that my dirty sound is near at 1 o clock at the dirty gain knob (ACDC like sounding, under, it has not enough gain for me), and my Dirty master volume is at 9 or 10 o'clock (it sounding pretty LOUD!!!) and so if i need to switch on the Natural during a song, the Natural volume is weaker, and so the sound volume is not balanced during the song....(hope that u understand what i mean...poor French man that i am!!!)
Does some others Rocker30 owners have noticed that annoying fact?

2nd problem: i find the gain on the dirty really comes after noon position of the gain knob, what can i do to make it come earlier, without sacrifying to much the clean that is already lacking?

I precise that all my preamp tubes are still the shuguang 12AX7 that was in my head when i bought it.

Thank you really much for your help.

[a.hun]

Hi Andy and everybody,

does it means that it's impossible to have more headroom and power/volume (by staying 100% clean) on the Natural (maybe by putting a 5751 in V1) without making the dirty gain starting "further" that it already does?
Because my problem is that my dirty sound is near at 1 o clock at the dirty gain knob (ACDC like sounding, under, it has not enough gain for me), and my Dirty master volume is at 9 or 10 o'clock (it sounding pretty LOUD!!!) and so if i need to switch on the Natural during a song, the Natural volume is weaker, and so the sound volume is not balanced during the song....(hope that u understand what i mean...poor French man that i am!!!)
Does some others Rocker30 owners have noticed that annoying fact?

2nd problem: i find the gain on the dirty really comes after noon position of the gain knob, what can i do to make it come earlier, without sacrifying to much the clean that is already lacking?

I precise that all my preamp tubes are still the shuguang 12AX7 that was in my head when i bought it.

Thank you really much for your help.

I'm afraid I don't think you are going to be able to do a whole lot about it. Thing is that an amp running clean will just never sound as loud as the same amp cranked into distortion. Not only does the distorted signal sound louder, it really is louder because the clipped waveform has a higher average RMS power. (And the Natural channel is truly clean - it is so low gain that any distortion you'll get cranking it is from the poweramp section, not the preamp.)

In fact while the R.30 is pretty poky for a 30W amp, the Natural channel isn't particularly loud. It is more mellow than cutting tonally. You could certainly make it cut more by using an EQ in front but of course you'd be changing the tone. Basically if you want more clean headroom you'll need more power than 30 watts to get it.

The dirty channel seems to have an extra (3rd) gain stage which really cuts in above a certain gain setting. On my amp (and the others I've tried in shops) that is nearer 1:00 - 1:30 so if yours is doing it by 12:00 noon than that is probably already earlier than normal.

The amp does what it does, and while you can tweak things a little by preamp valve swaps that really isn't going to sort your problems IMO.


Andy.

[jerem37]

The dirty channel seems to have an extra (3rd) gain stage which really cuts in above a certain gain setting. On my amp (and the others I've tried in shops) that is nearer 1:00 - 1:30 so if yours is doing it by 12:00 noon than that is probably already earlier than normal.
Andy.

Hi Andy,

thanks a lot for your answer (that i was sadly guessing...)

In fact when i spoke about the real gain point on the Dirty gain knob, i wanted to talk about the point where it's really not clean, but just a very soft crunch. And for me this point is near noon.
But like you said, the real point where the sound start to be a bit agressive (to a classic rock sound, like ACDC i.e.) is with my Rocker 30 also between 1:00 -1:30. For me i thought it was the 2nd gain stage, not the 3rd (that i heard coming rather near 3:00 o clock..), but i might be wrong.
And it's this point that i would have like to move before, to have this sound but at noon...
Sorry for my bad explanation!!!

[jerem37]

Hi Andy and hi everybody,

even if, as Andy said, swapping preamp tubes can't bring the changes i expect, maybe it can help a little...
So i would like to have some advices about preamp tubes choice (type, brand etc) in the R30 (i precise i play it with a "fat" fender US stratocaster with Humbuckers that can split to single coils):

- in V1: a low microphonic tube that will bring more headroom, dynamic and punch to the Natural channel, well balanced in term of frequencies, with tighten bass, bit scooped mids and more sparkling highs than the actual chinese tube. It will have to be a "well-defined" tube as it is also the 1st gain stage of the dirty....
I thought about a 5751 (sovtek, or rather a GE/JAN...) but, as i would have more power/volume on the Clean and to have the "good gain" i spoke about before to come earlier on the Dirty, perhaps it won't be the best bet...

- in V2: a tube with a good amount of gain, without too much compression, well balanced (not too dark) with the great mids that makes Orange so famous and with good harmonics/highs (but also not too harsh!!!)
I have no idea for this position....

- in V3: a good PI tube (that will also bring if possible a bit more headroom on both channel) that will respect the tonal caracter of the two first tubes and more generally of the amp.
I thought to try a 5751 or a 12AT7 (for more headroom) but, as the tube normally installed is a 12AX7, i don't know if it's a good idea and if it's not dangerous for the amp...

I guess that what i ask is difficult, but if someone that knows tubes very well can help me, or if some R30 users thet have tried other preamp tubes can tell me about their choices, it will be very very kind and will help me a lot.
I previously really thank you for your answers and explanations.

[jerem37]

Hi,
nobody have ideas or some advices?

[MyAudioDNA]

I have an R30 and had the exact same problem as you did. I came up with a solution, and though it didn't entirely solve the problem it did help it some. Here is what my amp looks like right now:

v1: JJ 12AT7 - This is a lower gain tube which will give you some more headroom on the clean channel

v2: JJ ECC803s - This is a high gain 12ax7 that should keep midrange you are looking for

v3: JJ 12AT7 - This should do exactly what you mentioned, provide a bit more headroom

Though this combination won't completely solve the issue you described, it has helped me to get a more balanced sound between the clean and dirty channels and has overall increased my satisfaction with the amp.

[jerem37]

Hi,

and thank you very much.
The 12AT7 surprised me, especially in V1. You don't notice any volume loss on the natural? because it's a very low gain tube in comparison to 12AX7.
In fact, for a smaller gain difference, i thought about a 5751 in V1 (it's between the 12AX7 and the 12AT7...). Did you try it?
The 12AT7 instead of an AX7 in PI postion did'nt bring you loss of power, dynamics or reactivity? with it, is it possible to push the master volume of the dirty further than before with the 12AX7, at the same gain setting?

Nobody else with some ideas or advices for tubes choice?

[MyAudioDNA]

Hi,

I didn't notice any significant volume loss, no. Obviously there was a little bit, but imo not enough to really make a difference. I have not try a 5751 in that position.

I again didn't really notice a significant difference putting the AT7 in power, dynamics or reactivity. Replacing it gave me about one extra notch on the volume knob.

[BertusJ65]

as a.hun stated changing preamp tubes will not solve the volume issue between the 2 channels
His suggestion a an eq or maybe even a boost pedal for the clean channel would be more effective.
I find the clean channel to be a bit dull myself.
The amp in general is pretty mid range heavey.
I find it sounds best the louder you can play it
best of luck
respectfully Jon

[jerem37]

Hi,

Bertus, you're probably right (like Andy already told me)
I bought some 12AX7 just to try to improve the tonal caracter/response of my amp in comparison to the factory chinese preamp tubes.
For the clean, perhaps a good clean boost, i.e. a Xotic RC booster, would be the best bet.
Thanks for your answer.

[a.hun]

The 12AT7 surprised me, especially in V1. You don't notice any volume loss on the natural? because it's a very low gain tube in comparison to 12AX7.

You wouldn't notice a volume loss because although lower gain the actual output can be the same or even a little higher than a 12AX7. Gain is one thing, output level is another.

Thats useful info MyAudioDNA - thanks for that! Of course since the 12AT7 in V1 is also the first gain stage of the Dirty channel that alone would change its tone and gain some.

Likewise the 12AT7 in V3 (PI slot) will affect the overall tonality of both channels. That trick often works really well with Mesa amps.

You are probably finding the amp a bit less midrangy with more pronounced highs and lows, and enjoying the extra note definition that gives? Fair comment?


Andy.