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Super Basic Question for a noob

Started by megatrav, December 28, 2023, 03:02:36 PM

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Quote from: phatt on February 20, 2024, 08:59:41 PMhi Megatrav,

Wise not to focus on one aspect like Efficiency.
Heck, Valves waste a lot of energy as heat yet they are still considered the holy grail of tone for a lot of guitar players.
There are just so many rabbit holes in this field that are mostly a waste of time.
I have 3 Valve Amps but my main setup is a pedal board which delivers a great sound into an old 70's 80's era Keyboard Amp.

If you research how Valves actually work you will realise that a lot of the magic is due to a very poor Power supply.
Depending on the design With no signal the HT voltage might read 400VDC in a valve amp. Turn up the volume and hit a big power chord hard and that 400V will drop like a brick, You might see it drop by 100V or more, depends on The ability of the PSU design.
As that signal fades away that voltage rises back up.

This is effectively causing compression so the sound level actually drops and limits the absolute SPL and as the Voltage rises back up it gives the impression of more sustain.
But with SS amps the supply voltage is very stiff and hence no magic sustain.
A SS 40 volt supply might only sag 2 or 3 Volts and by then you get into hard clip which is ugly, so hence SS gear gets a bad reputation.

So to recreate that effect with SS gear you will need a compressor.
I do all of that with my pedal board and the Amp just makes it louder.
The Amp adds very little colour to the final sound although it does have a spring Reverb which adds a final touch. I use 3 OD dirt pedals into my Compressor.
the Gain of all 3 dirt pedals are set fairly low and as you turn each one on you get more drive. And the compressor does 2 jobs obviously it adds compression but it also keeps the absolute SPL in a set range so when I play leed parts nothing gets too loud.
I use an optical compressor as they tend to work very well for OD rock guitar sounds.

As for Class D stuff I've noticed that the freq response often goes down way too far and that can be a big problem if you are trying to reproduce the classic sounds.

Understanding and limiting the bandwidth of your gear will help refine your sound.
Too much Low and High freq will just frustrate you and drive you crazy.
There are many ways to great tone and even when you get there you will find that different venues and rooms can give different results. I have built many circuits and thought I had cracked the holy grail only to find that when I played live it sounded like crap.

If it interests you I posted a recording of my gear on here a while back.
This will give you some idea of what can be done with all SS gear.
Regards from an old bloke who has spent lots of time down these rabbit holes, Phil

I get what you are saying.  I definitely understand voltage sag being part of classic tube amps.  I don't think that is usually the case with more modern high gain tube amps.  It is also not the case with amps like HiWatt that had very well-designed power transformers and output transformers.

But yes, there is definitely something about the way an output transformer will affect frequency response and interact with the speaker. Solid State amps have to have that built in as emulation (compressor circuits and/or post preamp EQ) or sometimes additional voltage regulating circuits that work similar to tube amps but don't actually affect the power or output.

Efficiency is important if the end goal is smaller, lighter, and cooler (temperature).
As for Class D frequency response, I can't agree that this is the case 100% of the time.
2 real solid examples of great sounding Class D amps are Quilter and the Victory V4 amps which have tube preamps running at high voltage (I assume at least 250v) that go into a power amp emulation, then a Class D output stage.

If you listen to any clips of them, I don't think you can say they sound bad or have bad frequency response.

As for recording, I have no problem using plugins or my HX Stomp. They sound great to me.  I would really love to build my own hybrid amp with a tube preamp and solid state power amp for gigging.  Class D seems like the obvious choice given what I stated above.


Fair point if you want ultra light.
and yes I have no doubt if you have an understanding bank manager then quilter and like stuff might be fine.
I play live and hence plugins and software stuff are no use to me.
I've heard they are realistic for recording but a lot of fussin for a live gig.
I take Guitar Amp and Pedalboard,, plug in and play.
When I do on occasion record my rig it comes out pretty close to what it sounds like live.


megatrav: I would really love to build my own hybrid amp with a tube preamp and solid state power amp for gigging.

Have you considered building / getting a valve stompbox from Sushi Box ?
He has valve pre-amps in stompboxes, add a DI and you could go straight to FOH.
Get a class D pedal amp and a speaker cab and you are ready to rock.
There are no stupid questions.
There are only stupid mistakes.