Uncle GAS Needs You: Help Design an All Tube Amp!!!

[luknfur]

You're dead on! The Baxandall is really cool in that if you cut the Bass and Treble controls, you get a great Mid boost as pictured here.
Your thoughts?

FWIW:

interesting to see those graphs. The ear hears what it hears and I choose to be no more technically literate than required (I wouldn't use it enough to remember anyway) but it's cool to see something technical to support what my ear was telling me WAS going on.

Sound really is a complex phenomenon.

 

[jokerjkny]

Two channels it is. It seems the vast majority of players are wanting this. The poll seems to back this up.

coolio,

may i be the first in line for the "50 watt guitar edition"...

A couple of thoughts. It's your amp, Brad, and I think it is coming together really nicely. But, if I were to get my complete "wish list", I'd also love to see the EQ bypass switch (at least for the 6SL7 channel), (...)

+134,522

i need that bypass switch.

and holy crap, its really coming together... its really happening!

 

[JacksonAmpworks]

Guys I'm sorry, the tone stack bypass switch is on each channel as is the Ultra switches. Here is the revised spec sheet.

01.) 6SL7 front end Channel 1
Channel 1 Controls

Volume
Treble
Bass
Ultra-Lo and Ultra-Hi Switches
Tone Stack Bypass​

02.) 12AX7 front end Channel 2
Channel 2 Controls

Volume
Treble
Bass
Ultra-Lo and Ultra-Hi Switches
Tone Stack Bypass
Master​

03.) 6550/KT88 power tubes (6x @ 300W)
04.) Resonance and Presence controls (Global)
05.) Direct Out (XLR) - Selectable PREAMP (post FX Loop) or SPEAKER Tap
06.) Tube Buffered FX Loop
07.) Fixed Biased with Bias Meter
08.) 2-4-8 Ohm Selector Switch
09.) Speakon Connectors (1/4" and Speakon)
10.) 100W/200W/300W Switch
11.) Cathode Disconnect Standby (silent recording!)

 

[JacksonAmpworks]

A couple of thoughts. It's your amp, Brad, and I think it is coming together really nicely. But, if I were to get my complete "wish list", I'd also love to see the EQ bypass switch (at least for the 6SL7 channel), the ability to blend some clean low frequencies in with my overdriven tone, and a variable (at least two settings) damping factor control. Of course, I'd hate to end up being like Homer Simpson (D'oh!), so I throw these ideas out for you to use - or discard - at your discretion.

It was a mistake on my part. The EQ bypass exists on both channels. I'm not sure that we can "blend" the two channels easily. The reason being that I'm making every effort to completely isolate these two channels so that one channel does not effect the tonal integrity of the other channel.

You're going to love this! The Presence and Resonance are BOTH used to control damping factor! The Presence is used to adjust the high frequency dampening and the Resonance is used to control the low frequency dampening.

As for a Midrange control, I do like a tone that is balanced through the mids (I'm not a fan of either scooped mids or midrange "humps"), and I have found that if my cabs are fairly balanced through the mids, I don't need to mess with them. So while I have expressed some desire to see a midrange control with selectable frequencies for the "SVT side", my concern was just to be able to dial in/out mids to achieve a fairly balanced tone. If you can deliver that (with overdrive/distortion) from the 12AX7 channel without the need for a midrange control, then I'm cool with that.

Being flat is where the Baxandall tone stack really shines. When both the TREBLE and BASS controls are set at 12:00, the EQ is flat as a board! That's one of the reasons why I have always enjoyed working with this type of EQ. Add to this the incredible flexibility of the Baxandall tone stack and you can see why it is so highly regarded!

Great comments guys!

 

[JacksonAmpworks]

I thought the dampening was the resonance control? I have no idea what dampening does, so you'll have to excuse my mental handicap

That stuff is on my wishlist too, but if it can't be done or messes up the tone i'm totally cool with it.

You are right! The Resonance as well as the Presence control do control dampening for their respective frequencies. The Resonance has command of the low freq. and the Presence has command of the high freq.

It's on my wish list as well.

 

[JacksonAmpworks]

It may be. I have seen that same term - "resonance" - used for apparently different methods of altering the tone. If it is a damping factor control, then whoo hoo!

It certainly does effect the damping factor! Woo Hoo!!

 

[JacksonAmpworks]

I'd like to hear what a 'resonance' control does as well. If I had to hazard a guess I would say it was a notch filter in the neg feedback in the output stage, but that's only a guess.

Which other amps have 'resonance' controls? I've seen wah-wahs with that but that's just a band-pass filter where the control varies the Q (peakedness?) of the filter.

I've seen the Resonace control in the 5150 amps. Basically it is used to control the low end of the amp. This is really cool for bass amps because you can tailor the low end of the amp to work well with the resonant frequency of the speaker cabinet. "It's a good thing."

 

[JacksonAmpworks]

coolio,

may i be the first in line for the "50 watt guitar edition"...

I hadn't thought of making a 50 watt for guitar edition, but now that you got me thinking....

i need that bypass switch.

You got it!

and holy crap, its really coming together... its really happening!

Thanks to you guys it is!

 

[Fretless5verfan]

I've seen the Resonace control in the 5150 amps. Basically it is used to control the low end of the amp. This is really cool for bass amps because you can tailor the low end of the amp to work well with the resonant frequency of the speaker cabinet. "It's a good thing."

well THAT sounds promising!


Side Note: I found the peacemaker amp by complete serendipity. How odd is that? Mojave's really heavy distortion (peacemaker, scorpion) sounds freakin incredible, but i have to say, the more bluesy tones of thier heads seem like they get smoked by the Atlantic and the Union Jack big time I'm definately gonna have to grab one of those and a cab from ya for my studio pretty soon

 

[JacksonAmpworks]

well THAT sounds promising!


Side Note: I found the peacemaker amp by complete serendipity. How odd is that? Mojave's really heavy distortion (peacemaker, scorpion) sounds freakin incredible, but i have to say, the more bluesy tones of thier heads seem like they get smoked by the Atlantic and the Union Jack big time I'm definately gonna have to grab one of those and a cab from ya for my studio pretty soon

I have several in stock, so let me know and we'll get you set up in style.

 

[JacksonAmpworks]

Here is a copy of a post I made on the Poll post. It outlines the problems with the blend channel and how it will compromise the tone of each channel.

Seriously this is a REALLY cool idea, but it will compromise the tone of each channel. Also there would be phase issues to address that would require that I alter the gain structure of one of the channels.

It works like this:

The 6SL7 channels has two gain stages.
The 12AX7 has two gain stages.

If I mix these two channels together, they will cause phase problems with each other. The only way to avoid this is to add a gain stage to either the 6SL7 or the 12AX7 channel.

Think of it this way: The number of gain stages in the channels that are going to be blended cannot both be even or odd. For instance, a 2 gain stage channel cannot be blended with another 2 gain stage channel. One of the gain stage numbers has to be odd and then it can then be mixed with a channel that has an even number of gain stages.

Is that clear as mud?

The reason that I say that is to demonstate that having a blend control will necessitate the modification of one of the channels, which would unfortunately alter the original tone of each channel.

 

[tombowlus]

You're going to love this! The Presence and Resonance are BOTH used to control damping factor! The Presence is used to adjust the high frequency dampening and the Resonance is used to control the low frequency dampening.

Oh, man! I was hoping you were going to say that! Sa-weet!

 

[JacksonAmpworks]

I forgot to mention something guys. Actually this one just dawned on me while I was working on the schematic for the amp. We have been talking about adding a gain stage for a while and it just hit me.... THIS AMP ALREADY HAS A GAIN BOOST ADDED!!!

The FX loop is buffered with a tube and then sent to the FX send, the FX Return has a Tube Gain Stage that is meant to amplify the return signal back to line level. While thinking about it, I realized that all you have to do is put a patch cable between the FX SEND and RETURN and now when the FX Loop is enabled, all you have to do is adjust the send and return levels to adjust the ammount of gain boost that you want. This gain boost would apply to both channels and would make a great level boost or OD boost!!



Now we have it all! Independant channels + a gain boost!

 

[jondog]

Perfect!

 

[specplyrz]

I have a suggestion for a name for your amp.... "tonare".

Pronounced tone-are. Latin for "thunder".

Wadaya think?

 

[Biker4Him]

I forgot to mention something guys. Actually this one just dawned on me while I was working on the schematic for the amp. We have been talking about adding a gain stage for a while and it just hit me.... THIS AMP ALREADY HAS A GAIN BOOST ADDED!!!

The FX loop is buffered with a tube and then sent to the FX send, the FX Return has a Tube Gain Stage that is meant to amplify the return signal back to line level. While thinking about it, I realized that all you have to do is put a patch cable between the FX SEND and RETURN and now when the FX Loop is enabled, all you have to do is adjust the send and return levels to adjust the ammount of gain boost that you want. This gain boost would apply to both channels and would make a great level boost or OD boost!!



Now we have it all! Independant channels + a gain boost!

dude... that rocks!

 

[jokerjkny]

I forgot to mention something guys. Actually this one just dawned on me while I was working on the schematic for the amp. We have been talking about adding a gain stage for a while and it just hit me.... THIS AMP ALREADY HAS A GAIN BOOST ADDED!!!

The FX loop is buffered with a tube and then sent to the FX send, the FX Return has a Tube Gain Stage that is meant to amplify the return signal back to line level. While thinking about it, I realized that all you have to do is put a patch cable between the FX SEND and RETURN and now when the FX Loop is enabled, all you have to do is adjust the send and return levels to adjust the ammount of gain boost that you want. This gain boost would apply to both channels and would make a great level boost or OD boost!!



Now we have it all! Independant channels + a gain boost!

cool,

but i've been told by some guys who's amps have a similar setup NOT to do just that. i.e. my Fuchs, and my TR's.

what's the diff?

 

[JacksonAmpworks]

cool,

but i've been told by some guys who's amps have a similar setup NOT to do just that. i.e. my Fuchs, and my TR's.

what's the diff?

Man I can't imagine why not. You're just adding another gain stage.

 

[DEVILMAN]

...hmmm, I'd LOVE to try this with my Traces or Kern but have a bit of fear of the dreaded "fried & dead" aftermath from "good experience/bad mistake" experiments...

~S~

 

[jokerjkny]

Man I can't imagine why not. You're just adding another gain stage.

if i try this tonight, and all goes awry, may my ghost haunt your shop until i get a free jackson amp!