Tonal differences between different solid state POWER amps?

[JohnLawrence]

All else being equal (cab, speaker, etc), would plugging into the effect return of one SS amp be any different than any other? If I already have a cab and preamp, should I just get the cheapest, high wattage amp (with an effects loop) that I can find?

TIA

 

[redhouse_ca]

I don't know from recent experience, but it's a good question, tho. When I've played through solid state amps the sound quite different but i don't really use peddle. I would guess if a lot of your tone is related to the sound of the peddles/FX, the differences will matter a lot less.

It will be interesting to watch this thread.

 

[JustABluesGuy]

If using the same cab and preamp they should sound similar. As I understand it most SS amps get their distortion from the circuitry that precedes the power amp.

I haven’t done any side by side comparisons though so…

 

[redhouse_ca]

If using the same cab and preamp they should sound similar. As I understand it most SS amps get their distortion from the circuitry that precedes the power amp.

I haven’t done any side by side comparisons though so…

Great point on preamp.

 

[codamedia]

Older style power amps are full blown circuits and IME, the do add color the the tone. For example, an old school Peavey CS Power Amp sounds different from an old school Crown and reacts differently when pushed. I believe modern power amps (even guitar amps) will have more consistent "sounding" power amp sections.

would plugging into the effect return of one SS amp be any different than any other?

Maybe, but I don't think it will truly matter as long as you don't "underpower" your needs. Get more than enough power and let the pre-amps/effects do all the tone shaping.

 

[bottlenecker]

Some sound better than others. Don't know why.

 

[JohnLawrence]

Some sound better than others. Don't know why.

Plugging into the PA of my TM60 (chip amp, sounds quite passable), vs the PA of my old "solo series" Bandit (all discrete, dull and spikey sounding, immediate ear fatigue) seems to confirm this. Same speaker - EV Force 12, and similar cab dimensions.

 

[bowman]

I can’t really answer the question, but I like those little SS amps. I have a Crate Power Block that I bought back when they were all the rage for small, powerful backup amps. It was one of the first amps made for that purpose. I always liked the thing, but never used it for guitar - it’s a keyboard amp for me: keyboard >150 watt Crate>4x10 cab. It a great amp for that purpose - I even use guitar pedals with sometimes.

 

[TequilaCaster]

Solid State Power Amps are designed to be clean power amplification with as little crossover and harmonic distortion as possible. So the quality of your resultant tone will all depend on the kind and amount of distortion generated by you preamp as well as the combined EQ equaliztion of your pickups, preamp circuitry (fx pedals) and the particular speaker(s) you are using.

Electric guitar distortion can be that warm 3-D pleasant 2nd-harmonic kind you might get from a JFET preamp like a EP boost, or gnarly odd-harmonic overdrive-distortion-fuzz you might get from a RAT pedal.

The thing to watch for with SS power amps is their input sensitivity ... how much input signal is required to drive them to their full output. Generally amps with lower input levels work better with guitar pedals. 0.775 volts preferred over 1.4 volts input sensitivity. If you are just plugging into the effects loop of a SS guitar amp, you probably don't have to concern yourself with the input sensitivity level, as it's already been considered for you.

Many SS guitar amps power section have 'current feedback' incorporated to try to mimic the interaction that a tube amp's output transformer has with the attached speaker, which essentially results some amount of bass and treble boost, so that the speaker does not sound too dull or middy (not muddy).

 

[ficelles]

SS power amps are generally designed to do nothing more than amplify, i.e. not colour or distort the input signal, so should in theory all sound much the same.

Many modern Class D power amps use the same power modules, so that should apply even more so.

 

[printer2]

Class D are said to not clip well. Analog amps will mostly sound the same until you clip them, when they do they can sound vary depending how well they were designed to recover.

 

[ficelles]

Class D are said to not clip well.

Understatement, trust me. Particularly with bass amps, Class D clipping is horrible.

 

[Dacious]

The amps themselves should not vary in sound. What will vary is speakers if you're talking combo or frfr type plastic box amps. And many amp makers now include DSP processing post-eq and power protection modes which will colour sound by reducing rather than cutting sound like older systems. You'd have to understand the two particular amps and any circuitry implemented.

By and large speakers is the single biggest determinant of sound with solid state. Modern amps won't clip at all - it's instant destruction. The obnoxious tones you hear if you drive one to clip is the protection system cutting in and out. If you get one howling with feedback you'll cook a speaker.

I've had two modern class D PA amps bust drivers - a new speaker returned them to function. They don't even get hot run continuously in a club at 110°f heat. If they do go it's usually the power supply.

 

[redhouse_ca]

Solid State Power Amps are designed to be clean power amplification with as little crossover and harmonic distortion as possible. So the quality of your resultant tone will all depend on the kind and amount of distortion generated by you preamp as well as the combined EQ equaliztion of your pickups, preamp circuitry (fx pedals) and the particular speaker(s) you are using.

Electric guitar distortion can be that warm 3-D pleasant 2nd-harmonic kind you might get from a JFET preamp like a EP boost, or gnarly odd-harmonic overdrive-distortion-fuzz you might get from a RAT pedal.

The thing to watch for with SS power amps is their input sensitivity ... how much input signal is required to drive them to their full output. Generally amps with lower input levels work better with guitar pedals. 0.775 volts preferred over 1.4 volts input sensitivity. If you are just plugging into the effects loop of a SS guitar amp, you probably don't have to concern yourself with the input sensitivity level, as it's already been considered for you.

Many SS guitar amps power section have 'current feedback' incorporated to try to mimic the interaction that a tube amp's output transformer has with the attached speaker, which essentially results some amount of bass and treble boost, so that the speaker does not sound too dull or middy (not muddy).

Sound like you know SS pretty well for guitar stuff (better than me, for sure). Kinda related but not exactly, do you think digitally modeled distortion sounds better than SS distortion? I realize they are both on solid state hardware at some level, and I have no opinion on this because 95% of what I know is tube or modeled, but I just thought about this with your comment (thanks). I'd love to get your opinion.

 

[Dacious]

Sound like you know SS pretty well for guitar stuff (better than me, for sure). Kinda related but not exactly, do you think digitally modeled distortion sounds better than SS distortion? I realize they are both on solid state hardware at some level, and I have no opinion on this because 95% of what I know is tube or modeled, but I just thought about this with your comment (thanks). I'd love to get your opinion.

Drive solid state into distortion, even driver chips for a phase inverter will cook if you put enough square wave through them. To a chip square wave looks like a dead short. That's what eventually killed many. Analogue solid state does not like square wave.

Modern solid state amps are kept as far from distortion as possible. All the tone generation/distortion is done in software. It's like playing metal through your car audio.

 

[redhouse_ca]

Drive solid state into distortion, even driver chips for a phase inverter will cook if you put enough square wave through them. To a chip square wave looks like a dead short. That's what eventually killed many. Analogue solid state does not like square wave.

Modern solid state amps are kept as far from distortion as possible. All the tone generation/distortion is done in software. It's like playing metal through your car audio.

Thanks. It shows how long ago it was that I plugged into a solid state amp. I was curious about the overdrive in solid state va modeled distortion (I should have been more clear). I have no idea what the overdrive cct looks like (I'm gonna look it up out of curiosity). from what you said, it sounds like that's not done in the op amp.

 

[ficelles]

Drive solid state into distortion, even driver chips for a phase inverter will cook if you put enough square wave through them. To a chip square wave looks like a dead short. That's what eventually killed many. Analogue solid state does not like square wave.

Any synth or fuzz pedal will put out a square wave - like any other type of wave it's just an AC signal. If square waves killed amps then keyboard players would be like the Vlad the Impaler of the amplification world. The idea that a square wave equals a short (or is DC) is a common misconception. However an SS amp that is pushed into hard clipping will put out way more than its stated power, and under those circumstances SS amps are great speaker destroyers.

 

[redhouse_ca]

Any synth or fuzz pedal will put out a square wave - like any other type of wave it's just an AC signal. If square waves killed amps then keyboard players would be like the Vlad the Impaler of the amplification world. The idea that a square wave equals a short (or is DC) is a common misconception. However an SS amp that is pushed into hard clipping will put out way more than its stated power, and under those circumstances SS amps are great speaker destroyers.

That is the best visual of a keyboard player I have ever imagined.

 

[mexicanyella]

I use either of two different rackmount solid state power amps in my bass rig. One is a early 1980s Peavey M-3000...essentially the power section of one of the Mark series bass heads, or a Combo 300 1 x 15 bass combo...in a shallow steel 3U rack box, without all the preamp jimjam up front.

It will deliver 130W into my 8 ohm Hartke 4 x 10 or 210W into my 4 ohm AudioKinesis 4 x 8”.

The other is a late 80s/early 90s Crown MicroTech 600, which will deliver 750 watts bridged into the 4 ohm cab or 655 watts into the 8 ohm cab.

I have compared the two at high volume and have found that they don’t shape the tone differently, but there are dynamic response differences for sure.

The Peavey has DDT speaker protection limiting built in, and that adds a compressed feel as you get the amp’s meter lit all the way up. Bass response and “slam” is softer, mushier, but that actually suits our music pretty well. Volume is adequate through the AK cab, which is more efficient. Through the Hartke it will get me By, but I’m getting into that DDT action and it’s getting compressed and kind of bloomy.

The Crown power amp, by comparison, is like a cinderblock to the face. It just takes whatever you give it and slams it into you. Transients from muted or ghosted notes are felt in the solar plexus. Zero squish or bloom, just slam. It’s kind of intoxicating, and will go much louder than the Peavey. Sometimes I perceive it as initially intoxicating but ultimately fatiguing.

A good argument could be made that there is a “turn it down” cue there that I am missing, but I have found that surprisingly hard to do. The slam is so cool...

So I don’t hear tonal differences or coloration, but there are pretty major response differences, partly due to available power and partly due to Peavey’s DDT limiter circuit kicking in.

One additional thought: I have a Peavey Special 150 guitar combo, and have used it to power my 4-ohm cabinet a few times as a backup bass amp. I have found its power section to be “spikier” than the M-3000, but not dull in any tonal coloration way. I attributed the difference to the lack of DDT limiting kicking in like the M-3000 has. I suppose I should disable the DDT sometime and compare...but I usually enjoy the slight squish it imparts when I drive it hard.

 

[TequilaCaster]

Sound like you know SS pretty well for guitar stuff (better than me, for sure). Kinda related but not exactly, do you think digitally modeled distortion sounds better than SS distortion? I realize they are both on solid state hardware at some level, and I have no opinion on this because 95% of what I know is tube or modeled, but I just thought about this with your comment (thanks). I'd love to get your opinion.

Yes it is good to distinguish Analog Solid State (ASS?) from digital solid state (DSP digital signal processing). No, I do NOT find digitally-modeled distortion to sound better than 'analog' SS distortion. But everybody likes what they like and that's OK with me. I do like some digital effects like delay and reverb, but I prefer the sound of analog SS distortions. OK... I admit... my rig's distortion sounds like ASS(!) ☺And I love class-d amps with a warm JFET preamp in front, much more than tube amps these days.