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What's the big deal with little amps?


Special J

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I love the idea of small amps. It's the same idea that it's more fun to drive a slow car hard than a fast car gently. It seems like a perfect choice for those of us who are primarily home players.

Trouble is when it goes from idea to reality, something goes wrong. The small amps just seem to be harsh, limited, and generally disappointing. I've only tried the cheaper mini amps, not the expensive stuff, but my basic theory is that a mini-amp only makes any kind of sense when you simplify the circuit. If you go ahead and build a full featured proper pre-amp, you may as well bolt it to a real power amp with a matched pair of tubes. That puts your sweet spot in the 15-30W range. Once I stepped up from the toy tube amps to the current JCA22h, things finally started to sound decent. And the reason I stopped at that size was mostly about weight.

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Loudness is not measured by the number of watts a head produces or the speaker consumes. Loudness is a matter of decibels the combination of the two produces.

It comes down to this. For a small practice amp, really only need enough volume/dbl level and body to sound good jamming to a Hi Fi stereo to learn songs. A 5 watt amp with an efficient speaker can easily match the midrange guitar tones in a song playing back through a 10~50W HiFi System with decent sized speaker cabs. 

You only have to match the guitar part playing back in that system. If the amp is too loud or has too much body, it will mask the sound of the other instruments playing back through the HiFi speakers making it difficult to match the guitar parts in volume and tone. Most solid state practice amps with an 10" or smaller speaker and master volume are fine for practicing to a HiFi system with 12" woofers.  

When it comes to playing with a drummer its a whole different ball game. You have to match the drums in DB level to be heard with a balanced level. A 12" snare can easily generate levels of 120db or more. A right with a 12" speaker is a favorite for matching the drummers snare which is the loudest drum in the set. Bass can get away with a single 15" to match the larger kick drum.

For a lighter drummer, you can get by with a 30w tube or 50w SS amp with medium SPL speakers. For a hard rock drummer, you'd more likely need a 50w Tube or 100W solid state head just to match the drummers transients without being buried in the mix. Most 30W combos will give you just enough clean mids for matching a drummer. If you want full bodied sparkly cleans you probably have to have more power.   

Keep in mind, A 30W head with high SPL speaker of over 100db can easily sound as loud as a 50W amp with medium SPL speakers or 100W with low SPL ratings. One of the problems with small practice amps is when it comes to small 8" speakers, the variety of replacement speakers is low.

If the amp has a 10" or above there's a huge variety of speaker types and ratings to choose from. You can easily beef up a small amps volume and/or tone by using a different speaker.

The other factor is cab design. A small cab is pretty much going to sound small no matter how many DB's it produces. It can only move so much air or produce so much bass. Many combos use an open backed infinite baffle to increase the bass response but for a bigger sound, you just need a bigger cab to produce more body.

Then there's the other factor. Many small practice amps sound awful connected to a large cab. Two main reasons being, the head is not "voiced" for a large cab, and higher wattage speaker in the cab require a higher wattage to overcome the "minimum sensitivity" ratings of the speakers.

This leads to the big mistake many make in trying to beef up the sound of a small amp. They think by sticking a high wattage or multiple speakers on the head it will sound better. Well, multiple speakers consume more  power and you only multiply power loss in the form of heat.   If you go up in wattage and not is efficiency (SPL), nothing is gained and in fact, it can produce less power and good tone because the speaker needs a minimal wattage just to begin moving to produce sound.

You can usually get the best tone by matching the head and speakers Peak/RMS ratings. You can even go up on the speakers wattage rating of say double and still get pretty good sound. Any more than that you start fighting the speakers minimal wattage rating. The sweet spot is to drive a speaker at 50~70% of its Max rating and you'll get its best tone. That is with all other factors being equal. For example, High wattage, high SPL speakers can still sound good with a low wattage amp, but you aren't going to produce the optimum tone the speakers are capable of producing. 

There's other factors of course. Room acoustics and cab design. Main thing is if the small amp is good enough to play through and keep your fingers in shape, and you can tolerate its tone, that's about all you need. I have a small 15W Marshall I picked up at a pawn shop. I keep it on a table next to my easy chair in the living room for practicing my riffs and even doing some occasional recording. Its OK for what it is and no more. Its tone and drive is pretty much a one trick pony. If I use it for setting up a guitars action I can pretty much rely on the guitar sounding good through a bigger amp which is all that matters.

If I want better tone from a small amp, I have an old silver faced Ampeg 10 watt amp. Its got a 10" speaker and a larger cab and really sounds good for clean guitar. It hasn't got any drive settings, just volume and treble and bass, but it sounds pretty good for an old solid state amp.      

 

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I've got a few decent amps in the 50W+ range, nice live amps that will work in most venues.  Then I have a couple of 100W all tube numbers to choose from if I need to be particularly loud and I suppose if I needed to be really crazy I could go with a multi-amp setup.  But that's all for live play and of little use to me at home.

At home I'm either playing casually for relaxation, practicing something or laying down some tracks.  I find a modeler works best for me in all of those scenarios.  I live in a sleepy surburban community and really don't want to subject my neighbors to an all out 100W Blackstar assault on the weekends.  Most of my neighbors don't even know i play guitar and I'm good with it staying that way.  Besides that my wife is usually watching TV or something and she's got just as much right to enjoy our home as I do.  OK, I may crank it up a little when she goes shopping.  Anyway...

The modeler is consistant. is not subject to room acoustics, doesn't care if the heater is running next to it in the winter while I'm recording, gives me many variants for different guitars, etc, etc, etc...

Bottomline, it just works better.

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I'm mostly a bedroom guy with the occasional going out to play with friends. I have an Epiphone Valve Jr combo which I think is a great amp and a Blackheart Little Giant that I run through a 12" Texas Heat Patriot speaker. I like both of these amps a lot and while I absolutely would like to have a nice Fender twin but it would be way more than I would ever use 99% of the time. I do understand the 4-12 attraction however I personally will never need a larger set up than I have. I enjoy exploring the low wattage market and the little gems that reside there.

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Promit wrote:

 

 

I love the
idea
of small amps. It's the same idea that it's more fun to drive a slow car hard than a fast car gently. It seems like a perfect choice for those of us who are primarily home players.

 

Trouble is when it goes from idea to reality, something goes wrong. The small amps just seem to be harsh, limited, and generally disappointing. I've only tried the cheaper mini amps, not the expensive stuff, but my basic theory is that a mini-amp only makes any kind of sense when you simplify the circuit. If you go ahead and build a full featured proper pre-amp, you may as well bolt it to a real power amp with a matched pair of tubes. That puts your sweet spot in the 15-30W range. Once I stepped up from the toy tube amps to the current JCA22h, things finally started to sound decent. And the reason I stopped at that size was mostly about weight.

 

But once you get to 15 watts and above, you've basically left the home player behind until you attach an attenuator.

 

My VHT Special 6 Ultra, with a 12-inch speaker, sounds pretty good at six watts.

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I don't know why we ever thought we needed such huge amps if we're not playing arenas.  And even THEN, they're not necessary at all.

 

I can do all kinds of daytime practice with my 30W Laney, and it sounds killer.  It's also got enough umph to play against drums. 

For any time that i want to play, I also have a Reverend Goblin that my (now ex) girlfriend bought me around 8 years ago.  5/15 switchable watts.  Anyone and everyone that's ever heard it or played through it has had nothing but great things to say about it.  No channel switching but easy enough to dial in, and it sounds great at speaking volume all the way up to full tilt.   I have to mic it to play with a drummer but it sounds great like that too.  Plus it is about 18 pounds and buckles in nicely in the front seat of my car.

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Danhedonia, my intention with the OP was to spark some conversation. It just stemmed from an observation I've made that whenever a new practice amp comes out that's got some marketing behind it, it launches multiple huge threads here. It's just never occurred to me to get excited over a $100 practice amp.

 

I'm quite aware of the physics behind the amps (I'm an audio engineer by trade) and I understand why they're used (I have a wife too). Just passin the time online. The responses have been great.

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Ok, and thanks for not getting up my nose about my genuine confusion.

 

I guess I sort of disagree.  I do agree that generally, the smaller and lower quality speakers in practice amps can be a real disappointment.  However, I think that many of those amps sound quite good when you route them through different speakers.

Which, to me, begs a question: why in hell don't manufacturers simply spend a little more to put nicer speakers into practice amps?

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steve\_man wrote:

I don't get it either.  I've tried and purchased a ton of small amps...only to either return them or sell them later.  Just can't get over the "toyish" tone that most of them put out.  I'll convince myself that the size/portability is worth the tradeoff, only to hate the tone later.  I have yet to find a small amp (speaker under 10") that sounds really good...

 These sound really good

champ

and you can turn them up for some really nice natural single-ended 6V6 compression

they sound even better with alnico speakers (8") in them

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