Tube Knobs

[piebaldpython]

In researching tube amps, I see that most have one of two type knob configurations. One is Volume plus EQ (Blackheart Little Giant and the other is Master Volume, Gain, Level (Palomino or Peavey ValveKing). So, which is better to dial in distortion/breakup/clean sounds????

 

[tunghaichuan]

In researching tube amps, I see that most have one of two type knob configurations. One is Volume plus EQ (Blackheart Little Giant and the other is Master Volume, Gain, Level (Palomino or Peavey ValveKing). So, which is better to dial in distortion/breakup/clean sounds????

Most of these little amps do not have a lot of preamp gain on tap. In fact most of the distortion comes from a relatively clean preamp driving the crap out of the power tube. At 5W this is louder than hell in a small room, but usually not loud enough to gig with.

The Crate Palomino uses an op amp before the 12AX7 to drive it, almost like a clean booster. This will push the 12AX7 into OD. So there is more preamp distortion in this circuit.

The Peavey Valve King 8 and Valve Junior are very similar in topology, but the VK8 has a tone control.

The Blackheart adds a treble/middle/bass tone stack which eats up a lot of gain, which is needed with a very sensitive tube like the EL84. The VJ gets around this issue by having a voltage divider in the preamp to pad down the gain.

Generally in these amps the master volume is a variable grid load resistor for the power tube. This is only partially sucessful as if you dime the preamp, and use the MV to adjust the overall volume, it can get gritty sounding at low volumes. With the MV all the way up and the preamp down, you get a clean sound.

I don't have much experience in playing the Crate or Peavey, so my observations are from looking at the schematics.

I find that the stock Version 3 Valve Junior has low clean headroom, but very good OD. The Blackheart has better clean headroom, but not as much gain. I find the cranked OD sound kind of lacking in the stock Blackheart amp.

None of these amps have gobs of clean headroom; they all start breaking up fairly early. This is due to the nature of the EL84.

Tung

 

[duhvoodooman]

At 5W this is louder than hell in a small room....

Lordy, I can vouch for that!! I play my Valve Jr. in a small room (about 12'x12'), and I almost never run the volume knob above 9 o'clock, since bleeding from the ears has never been high on my bucket list. Mine has been modded for a fair bit more gain, but even before modding, I rarely got up as far as 11 o'clock before it got painful. If you play in a small room and want to overdrive that EL84 power tube, I suggest one of three things:

• Earplugs/isolation headphones
• A power attenuator, like a Weber MicroMass
• A bigger room!

 

[piebaldpython]

WOW, thanks for the info. What a learning experience this is. ahhaa Hey, I hear you guys talking about different versions of the Epi Valve Jr. Uh, how do you know which version you would be getting if you picked one up now brand new????

 

[mrmudcat]

The new ones are the newest versions of course and atleast on the combos better overall improvments were made on newer versions.Great amps by the way I love the head/ cab version.

 

[tunghaichuan]

WOW, thanks for the info. What a learning experience this is. ahhaa Hey, I hear you guys talking about different versions of the Epi Valve Jr. Uh, how do you know which version you would be getting if you picked one up now brand new????

The first version was a combo only. Duhvoodooman has one of these and details the mods he has done to it on his web page.

Version two offered a redesign of the PCB and added unregulated DC filament to get rid of the filament hum that plagued version 1. Version 2 was also offered as a head.

Version 3 sports a better quality black PCB. The PCB in version 2 was green and lower quality. The pads lifted off of those version 2 boards unless you were very careful.

Mrmudcat is correct: if you buy a brand new one now, you are getting version 3. You can tell for sure by looking at the on/off switch. Version 2 has an "I" & "0" marked on the lighted part of the switch. There are no markings on the version 3 switch. Also, version 3 will have a 12-digit serial number. Version 2 has only 6 digits.

I believe Epiphone started selling version 3 amps last summer, so all of the version 2 stock should be gone by now.

I just bought two Version 3 heads at GC about a month ago. If you're lucky you'll get an amp that has a JJ EL84 in it already. Mine had the less desireable Sovtek EL84s :thwap:

HTH,

tung

 

[duhvoodooman]

Yeah, Tung knows chapter and verse on this, but I think they're at v.3 now, with the new ones upgrading the transformers (the OT, in particular, needed this) and using better tubes, notably a JJ EL-84 power tube. It's taken 3 versions, but they have the VJr just about right now. There are still some fairly straightforward component changes that can be quite easily made on the PCB to help the tone & add gain, but it's pretty darned good right out of the box now. :AOK: :rockon:

EDIT: Oops, I see Tung already beat me to the punch with his post. Oh, well--at least we seem to agree.

Am I right about the better transformers in v.3, Tung?

 

[marnold]

Yeah, Tung knows chapter and verse on this, but I think they're at v.3 now, with the new ones upgrading the transformers (the OT, in particular, needed this) and using better tubes, notably a JJ EL-84 power tube. It's taken 3 versions, but they have the VJr just about right now. There are still some fairly straightforward component changes that can be quite easily made on the PCB to help the tone & add gain, but it's pretty darned good right out of the box now. :AOK: :rockon:

I saw one of those in the guitar shoppe the other day. I'm going to have to try one one of these days. How is the construction of the cab/combo?

 

[duhvoodooman]

I'd get the head. The combo's small cab and cheap speaker are definitely a tonal constraint. Even with an upgraded Jensen speaker in it, I play mine through one of my two cabs quite often, for a bigger, richer sound.

 

[tunghaichuan]

Yeah, Tung knows chapter and verse on this, but I think they're at v.3 now, with the new ones upgrading the transformers (the OT, in particular, needed this) and using better tubes, notably a JJ EL-84 power tube. It's taken 3 versions, but they have the VJr just about right now. There are still some fairly straightforward component changes that can be quite easily made on the PCB to help the tone & add gain, but it's pretty darned good right out of the box now. :AOK: :rockon:

EDIT: Oops, I see Tung already beat me to the punch with his post. Oh, well--at least we seem to agree.

Am I right about the better transformers in v.3, Tung?

Right on all accounts, Vood.

The stock version 3 VJ sounds very good. The output transformer is better suited to the circuit and sounds very good. I'm debating on whether or not to replace them in my amps. The 125ESE will give better bottom end and smoother sound. But the stock OTs will saturate easier. I think this might give a better sound for the Marshallized mods. We'll see.

There are still a couple of changes in the preamp that will make the amp sound better, and the bias needs a little cooling off to prolong the life of the power tube, but the amp is 95% of the way there, stock. That is literally a few bucks worth of caps and resistors.

tung

 

[tunghaichuan]

I'd get the head. The combo's small cab and cheap speaker are definitely a tonal constraint. Even with an upgraded Jensen speaker in it, I play mine through one of my two cabs quite often, for a bigger, richer sound.

+1

I've never heard an 8" speaker I liked. A VJ head through a 1x12" cab kills the combo and the 8" speaker. I'm looking into getting a 4X12" cab. :dude: I used to have one a long time ago and am now sorry I got rid of it. :thwap:

tung

 

[duhvoodooman]

There are still a couple of changes in the preamp that will make the amp sound better, and the bias needs a little cooling off to prolong the life of the power tube, but the amp is 95% of the way there, stock. That is literally a few bucks worth of caps and resistors.

Yeah, a far cry from my v.1 combo!! I'm still not done with that sucker....though it really sounds pretty damn fine right now, especially since the OT upgrade. But you know me--always another tweak to be done to make it a smidge better!

P.S. I'd love to have a 4x12 cab, but in the small room where I play, it would be just NUTS!!