HXDA Schematics?

[John F]

I’m playing nearly the same amps. A limited edition 25th with a Panoramic Stereo for cleans.

Wonderfully versatile setup.

Yes, I agree!

 

[GGJJGG]

I think Les Lazio mentioned pushing the power tubes being the key to the fuller sound on the HXDA in another conversation hereabouts. I am still trying to figure that out, which perhaps why the Dumble preamp tube drive might not be for me? Any thoughts anyone?

 

[László]

I think Les Lazio mentioned pushing the power tubes being the key to the fuller sound on the HXDA in another conversation hereabouts. I am still trying to figure that out, which perhaps why the Dumble preamp tube drive might not be for me? Any thoughts anyone?

I didn't see this post before, sorry!

The thing to keep in mind is that preamp tube distortion sounds inherently different from power tube distortion. This is due to the different functions and power handling capability of preamp tubes vs power tubes.

Preamp tubes are meant to handle very low level signals, and they distort and compress very quickly when driven with higher level signals. The dirtier you run the preamp tubes, the more compressed the signal.

Crank the preamp gain, and the result is a certain type of distortion where you perceive less midrange, more bass, and different mid and high frequency harmonics (perceived sometimes as fizz) as the tube saturates. This can be good or bad, depending on one's taste in amp tone.

Power tubes have much more headroom than preamp tubes, they compress less, they compress differently, and they retain more fullness and less mush in the bass, and more detail in the mids when pushed to breakup.

Mids are where guitar tone lives, so the differences are very audible. Lots of players prefer the type of saturation that power tubes give them. The tradeoff is that pushing power tubes into distortion creates more volume.

Perhaps this explanation is why you have a preference for less preamp gain and more output tube gain.


A third option is to go the middle ground, run the gain on the preamp tubes lower, and turn the master volume up to involve the output tubes more.

On the HXDA I take the approach of running the master volume pretty high, about 3/4 of the way up, and the preamp tube gain pretty low. You get a big, full tone that is more balanced across the frequency spectrum.

I do the same with the DG30, and I even run my Mesas that way. This hybrid approach works fine for me.

 

[Alnus Rubra]

I didn't see this post before, sorry!

The thing to keep in mind is that preamp tube distortion sounds inherently different from power tube distortion. This is due to the different functions and power handling capability of preamp tubes vs power tubes.

Preamp tubes are meant to handle very low level signals, and they distort and compress very quickly when driven with higher level signals. The dirtier you run the preamp tubes, the more compressed the signal.

Crank the preamp gain, and the result is a certain type of distortion where you perceive less midrange, more bass, and different mid and high frequency harmonics (perceived sometimes as fizz) as the tube saturates. This can be good or bad, depending on one's taste in amp tone.

Power tubes have much more headroom than preamp tubes, they compress less, they compress differently, and they retain more fullness and less mush in the bass, and more detail in the mids when pushed to breakup.

Mids are where guitar tone lives, so the differences are very audible. Lots of players prefer the type of saturation that power tubes give them. The tradeoff is that pushing power tubes into distortion creates more volume.

Perhaps this explanation is why you have a preference for less preamp gain and more output tube gain.


A third option is to go the middle ground, run the gain on the preamp tubes lower, and turn the master volume up to involve the output tubes more.

On the HXDA I take the approach of running the master volume pretty high, about 3/4 of the way up, and the preamp tube gain pretty low. You get a big, full tone that is more balanced across the frequency spectrum.

I do the same with the DG30, and I even run my Mesas that way. This hybrid approach works fine for me.

Thanks Les, more knob turning for me (TWHS).

 

[László]

Thanks Les, more knob turning for me (TWHS).

Hah!

 

[GGJJGG]

I think this discussion has been great to focus me on the amps I like to play. I think I can see me rearranging the collection soon. In a good way.

 

[Alnus Rubra]

@László so the knob turning was a success thanks to you, pre-amp volumes adjusted down and master cranked up, nice tones!

 

[László]

@László so the knob turning was a success thanks to you, pre-amp volumes adjusted down and master cranked up, nice tones!

Sweet! Glad it worked!

 

[DreamTheaterRules]

@László so the knob turning was a success thanks to you, pre-amp volumes adjusted down and master cranked up, nice tones!

Go for the gusto! Master up AND pre-amp up! THAT'S the cranked plexi tone.

I'm still interested in an HDRX20, but NOT just as a clean amp/pedal platform. I'd push the pre-amp stage to at least 5 or 6 and the power stage, and tame it with the power station. Then, add fuzz, or OD to push it further for Jimi or other tones that those amps were used for.

 

[GGJJGG]

Go for the gusto! Master up AND pre-amp up! THAT'S the cranked plexi tone.

I'm still interested in an HDRX20, but NOT just as a clean amp/pedal platform. I'd push the pre-amp stage to at least 5 or 6 and the power stage, and tame it with the power station. Then, add fuzz, or OD to push it further for Jimi or other tones that those amps were used for.

I think I am going to sell mine now that I have the hxda

 

[DISTORT6]

Go for the gusto! Master up AND pre-amp up! THAT'S the cranked plexi tone.

Now THAT’S the spirit!

 

[DreamTheaterRules]

I think I am going to sell mine now that I have the hxda

Yeah, I'd rather have an HX/DA as well but they are getting tough to find and prices are high. Where are you located?

 

[GGJJGG]

Yeah, I'd rather have an HX/DA as well but they are getting tough to find and prices are high. Where are you located?

Outside Detroit. I got a pretty decent deal on mine on reverb.

 

[GGJJGG]

Les. Do the NOS really make that much of a difference? Trying to find the vendors who S the NOS.

 

[DreamTheaterRules]

Outside Detroit. I got a pretty decent deal on mine on reverb.

Should we talk?

 

[GGJJGG]

Should we talk?

Sure. Shoot me a message.

 

[bodia]

Les. Do the NOS really make that much of a difference? Trying to find the vendors who S the NOS.

Check this place out. The website is pretty 1994, but the info is great. He's usually got a good variety of hard to find tubes.

BRENT JESSEE RECORDING HOMEPAGE

 

[GGJJGG]

Some of those ain’t cheap! It’s probably a lesson in marginal utility…

 

[László]

Les. Do the NOS really make that much of a difference? Trying to find the vendors who S the NOS.

Yes. But it's not a 'hit you over the head', 'OMG' difference. It's more subtle.

NOS makes the amp more satisfying to play in the long term; there isn't that annoying high frequency ringing and harshness that you often get with modern tubes (though JJs are actually pretty darn good tubes, and that's what I'd use if I didn't have NOS).

In other words, that thing that makes you get tired of/bored with an amp after a while is gone, and it becomes a keeper. I installed NOS in my other three amps as well, it's kind of my M.O. when I get an amp once I figure out what it needs.

In the HXDA I have NOS Mullard preamp tubes, and NOS Siemens EL-34 output tubes. Incidentally, the Siemens tubes were recommended by Doug Sewell, who designed the amp. Doug felt they were closest to the much more expensive and hard to find NOS Mullard output tubes.

I installed this set of tubes probably in 2015 or so after the 30th Anniversary Experience when I met Doug. They still sound great, including the output tubes.

 

[László]

Some of those ain’t cheap! It’s probably a lesson in marginal utility…

As always, marginal utility is a relative measure: It comes down to what's useful for the individual, and what's marginal in terms of cost.

For me, it isn't marginal utility. I make my living at this stuff. For others, it might be, though it depends how into the details of tone one is.

The biggest thing that affects tone in any amp like the HXDA is the V1 preamp tube that handles most of the signal boosting in the preamplifier, and then the output tubes.

So if you can swing an NOS Mullard for your V1, and a pair of Siemens output tubes, you'd be hard pressed to know that the other two preamp tubes are modern - I'd recommend JJs for those.