BASS AMPS: Class D vs. transistor vs. tube

[Swiss Frank]

I play guitar with tube amps and have just played bass for years via a (big) home stereo.  I'm looking at getting my first bass amp.  Money's not really an object.  I don't gig but it'd be nice to be able to play a party in the park or a small bar if the chance came up.  I also would like the amp available for band practices at my place, so it needs to be be able to play in a room with acoustic drums.

I see a lot of class-D amps even by the big names.  Mesa seems to have discontinued its tube amps and now ONLY has class-D.  So:

Even if you have money for tube, even if you're not looking for 800W or what have you, is class-D good enough a lot of players are happy with that instead of the hassle with tube?

Or if some class-D amps are especially good while others are especially bad, any pointers of which ones to try and which ones to steer clear of?

Then more or less the same questions for transistor: do people who can easily afford a tube amp and for whom a tube amp would be loud enough still go for transistor anyway?  And if so any particular ones?

The most useful story I could hear is someone who literally sold their tube amp because their transistor or class-D sounded good enough...

(Genre could be reggae, power pop, funk.  probably not heavy metal.  Instruments include J, P, pre-EB SR, SR5HS, Ric, Alembic,  Peavey T-40)

[Grant Harding]

You say money is no object, in which case I'd get a powered (600w) Kemper and a nice cab. I realise that's probably way more than you want, but it's how I do bass. I use mostly Ampeg amp profiles and it sounds amazing always, plus I can add wah filter, chorus, compression, EQ, whatever I want per preset. The power amp is Class D, just neutral amplification, but the "amp character" comes from whatever amp was used to create the profile. 

In your case a good combo amp sounds like the right thing, but I'd go at least 200w if you're going to play with a drummer and not run the bass through a PA.

 

[isaac42]

I recently bought a class D amp. A Bugera Veyron 1000M. Plenty of power, small easily transported, sounds fine. I'm still dialing in the exact sound I want, but the fact that it doesn't have tubes doesn't seem to be a factor (there's also the 1000T, with a preamp tube, for people who insist on having a tube). I wouldn't say that it sounds better than my other gear, but different. The same is true of my all-tube heads as opposed to my tube preamp/class D power amp setup. There are good amps made in every configuration. What most appeals to me about the new amp is that I can put it, its power cord, a speaker cord and a guitar cord in a used laptop case and carry it in one hand or sling it over my shoulder, and it's at least as loud as any of my other amps.

[DeepEnd]

I have a conventional SS amp but if I were in the market for a new/used amp I'd take a hard look at Class D. As Isaac mentioned, the big advantage is weight. TC Electronic and others make Class D combo amps in the 250 Watt range that weigh less than 50 lbs. or so.

[daddymack]

I was very impressed with a couple of the MarkBass heads, the combos not as much...I really liked the Gallien-Krueger MB210, compact, lightweight, 500W/2x10"...punchy and deep.

Phil Jones makes some absolutely amazing lightweight amps that sound killer...pricey, but worth it. Eden [and stepchild Nemesis] make some outstanding bass rigs as well..

On the flip side...since you said price was no object, you can still get an Ampeg SVT Tube head, '300W 50th Anniversary Special Edition', 6550 output tubes [valves], XLR DI out, SpeakOn outputs and user biasing about US$2700.00 [€2433], plus a nice cab, like a Hartke HyDrive 1x12...around US$400.00 [€360].

[ThudMaker]

I'd go with class D in this day and age. The preamp makes all the difference in the world wrt bass tone from the different amp models.

[isaac42]

To the extent that power amps make a difference in tone, I prefer solid state over tubes. The low end sounds more solid to me. I think it may be the damping factor.

[jackcheez]

I’ve been using an EBS Reidmar 750 since July. It has a class D power amp and a solid state preamp. I would recommend these amps without hesitation.  Heaps of power and sounds very nice.  The TC Elextronic RS212 cab did not please my ear so it has been replaced with the 440 Live 2 x 12 pictured. I am a very happy player now. 

 

[Grant Harding]

That EBS looks really cool and the controls are seriously well thought out. Would love to try one. 

What bass do you play most through it?

[jackcheez]

1 hour ago, Grant Harding said:

That EDS looks really cool and the controls are seriously well thought out. Would love to try one. 

What bass do you play most through it?

Mostly a 2011 60th anniversary American P-Bass because it was the only one that sounded good with that TC Elec cab. Now that I have a better bottom I look forward to trying some others. 

The EBS is a little bigger and heavier than the other class D amps because of the solid state preamp. It’s still very portable and convenient. I carry it around in a padded laptop computer bag. 

[WRGKMC]

I've been playing since the mid 60's and both played bass myself and played guitar with really good bass players.

Over that time I've heard many bass amps. Some kicked ass and some sounded like total garbage.  By the time I was playing in rock bands, 50W tube guitar heads and 100W or more bass heads were pretty much the standard. 

Typically you could match a drummers kick running half volume using a 100W Tube or a 200W SS Amp.  You never want to run a bass amp maxed because it typically distorts transients/peaks.  Amp manufacturers rate RMS as clean watts so running a tube head at maybe 50/75% gives you the maximum clean RMS volume.  Rarely do you want distortion on bass so you simply wouldn't normally push them beyond that level. 

The reason I say a 200W solid state amp matches a 100W tube head is based on how they rate the SS Heads RMS volume. They used a test tone at 1K and crank it till it distorts. Thing is as the low bass frequencies are turned up they are going to going to distort speakers and transistors etc  long before it ever matches that 1K  RMS level.  SS is typically clean on those amps at 1K at max volume. Running an actual bass?  You're lucky to get half the clean wattage out of them which is why I typically say you want a minimum of 100W Tube or 200W SS to match a 50W guitar head. 

You can also add to that  the "Fleischer Munson" effect of how your ears hear frequencies vs loudness.  This is something very important every musician should realize.

In a nut shell, our ears are most sensitive at 1/2Khz and least sensitive below 100 or above 10Khz.  Given the fact guitar frequencies are also in those same midrange frequencies, they don't need to be nearly as loud as bass in order to sound equally loud to the ears.  In short, the first 50W of bass is usually just enough to get a heavy duty speaker working.  You usually need an extra 150W to pump air like a kick drum does. 

As far as Class D goes, I've heard several different types and I bought myself a 300W Ampeg Portaflex. I thought it might replace the 200W Crate head I had been using.

Actual usable volume ranges seem to be even less then the older style transistor amps. (at least the ones well built having large power capacitor reserves) Small Class D heads means small power supplies and physically small capacitors. Granted, they've come a log way at improving caps but the laws of physics haven't changed at all.

Power supply caps physical size has similarities to batteries.  SS Heads with large power supplies are going to recover quickly when you punch the bass hard. It can even have the sage of tubes with a properly designed circuit.  A Class D amp barely has enough reserve DC current to survive a heavy transient.  They may not distort, but they sure as heck don't give you the same kick ratio of a good tube amp either. They don't have the same touch sensitivity either.  This is mainly the result of how class D actually works.  In a regular SS amp, you have a direct relation between dynamics vs current flow.  You get a fairly linear increase in power between the input and output. If you hit a bass string harder, the amp output is higher up until you reach maximum saturation and flattens out. (distorts) 

Class D is a switching amp which means it doesn't idle like other analog amps.  It saves power and therefore the physical size can be small when the amp at rest condition consumes much less power. When working it converts the input sine wave to a digital frequency (Pulse width modulation) which is a representation of the signal and no longer a sine wave.  This PWM signal then triggers the power amp to reproduce a sine wave at a larger amplitude. 

There is no 1:1 connection or increase in gain like you have in a class A or A/B amp.  The process the signal undergoes is closer to how a radio wave is modulated then most other circuits amplify a signal. Its not quite a digital representation but its not that far off either given the fact ythe amp switches on and off instead of working in between those  two conditions like most analog amps.  Anyone lacking the experience working with standard amps are unlikely to notice any difference at all playing through one, but its quite obvious to me when O play through one.  Its more feel then sound too.   

For me, I haven't quite warmed up to using Class D.  If I had grown up using them maybe that opinion would be different.   I run that Class D amp in parallel with two other amps so I get to gear how the sound and react side by side.  To me the difference between them is pretty obvious. 

First impression playing through Class D,  I wouldn't try to run them above half power.  The sweet spot seems to be 50% or less.   Given how easy they are to overheat (and difficult to repair) I wouldn't press my luck pushing them hard either. Most electronic failures in class D amps are catastrophic and too expensive to repair when comparing the cost of a new one.  

Even though you can make the amp louder fidelity doesn't improve or remain flat when pushed hard.  When you crank a Tube amps you "Feel" the punch of the bass get stronger as the notes get louder.  Class D gets Choppier and lacks the same dynamic kick of a tube amp.  I think its because a standard amp is always running and "Above" zero when you hit a note so the transient hits its peak faster.  Class D is normally off. When you it a note it has to Turn on and get to its peak which takes longer. Class A or A/B are always part way there so they have a head start on where the peaks need to be.  Its like taking a car from 0 to 60 vs a car driving 20 and going to 60.  The one already moving will get there much faster. 

That's the best I can explain it because it involves more then just the way things sound, its also about the touch which is equally important.  The class D does well for me between 1/3 and 1/2 power but above that It doesn't trip my trigger.  You therefore probably want double the power of a standard SS or 4X the power of a Tube head to maintain the kind of touch response you'd normally have.  I can easily see a 100~300W for a practice amp,  400/600W Class D head for rehearsal and 800~1000W head for clubbing.  Of course different manufacturers may use different parts and rate the amps differently too but my recommendations here seem to be pretty normal based on the opinions or the bass players I know.   

[Phil O'Keefe]

On 8/26/2019 at 4:24 PM, daddymack said:

I was very impressed with a couple of the MarkBass heads

 

I reviewed the Little Mark Vintage recently, and it's a really impressive little head. Very light weight and compact, plenty (500W) of power. Class D power amp, tube preamp. 

 

 

[daddymack]

Just saw that one in an email...where is one I could try...? GC didn't have it yet, neither did SA...my bassist is looking for a hybrid bass amp, and I told him about this one...500W Class D is more than adequate for small room gigs.

[Verne Andru]

Tubes distort. That's why guitar players like them. Leo Fender spent his career trying to make his tube amps so they wouldn't distort as did Ampeg. If you're doing Motorhead, they're great but if you want a clean bass tone there are better options.

I really really liked my old-school Yamaha. It was transistor based but was still big and tough to hall around.

The Fender Rumble 40 is top of my list these days. 40 watt class D into a 10" speaker housed in a light plywood cabinet. Great for working on chops and rehearsing. For gigs take the XLR out into the front-of-house and use the cabinet for a floor monitor. Load-in and out all of a sudden doesn't appear so painful.

Class D is the way to go.

[isaac42]

All amplifying devices distort. The questions are how they distort, and how much. Tubes do more than just distort. Or, rather, they distort in more ways than we think of when we use that word.

Before they distort in the way we think of, that is, before they start to clip, they start to compress. They do this in a different way than a typical compressor, and this is, in my opinion, largely responsible for what people call the tube sound. Both the compression and the subsequent clipping tend to be asymmetrical, which preferentially adds even harmonics over odd, and evens are more musical, at least to most people.

I, like a lot of bass players, prefer a clean sound. If I want obvious distortion I can use an effect. I like the sound of tubes in a preamp, but I have found that I prefer a powerful solid state power amp. I have found that my inexpensive class D amp suits my needs, at least for now.

[WRGKMC]

Many of the popular Tube bass  heads do something very cool when pushed up to the limit before actually pushing them into distortion.  They can compress the notes and give you a very light touch on the bass strings, and the overtones are strong and harmonically in tune with the notes.

Transistor amps attempt to get something similar by adding either a Compressor or limiter to add sustain. Without it you have to work much harder trying to maintain even note dynamics.  I.ve used SS bass amps long enough to get those even dynamics but it does take a toll on my fingers these days. I'd gladly trade all of my bass heads in for a decent Ampeg V4B head. That head was ideal for rehearsal and gigs.  You think you'd need more then 100W for bass, but when it comes to clean bass tone that's not the case.  With the right cab and speakers, it can kick most SS heads below 500W into the gutter. 

There is something which occurs live which is very unique to the bass. The low frequencies can excite the entire room full and make it resonate. Its similar to how a speaker box multiplies the low frequencies, a  good room that's treated for sound or a properly built stage can make even a low wattage bass amp sound much bigger then it actually is.  I always used to have people telling me my 100W Ampeg amp was too loud and I never ran it above 1/2 power.  The rest of the band miced their 100W guitar amps just to balance things. Drummer was super loud in that band too, he was one of the harder hitting drummers I knew and he used oversized drums which produced allot of sound.