Why build a micro amp and not something a bit more capable?

joulupukki

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After building a flavor of @robrob 's Bassman Micro (here's my build thread: https://www.tdpri.com/threads/journey-of-my-bassman-micro-build.1100749/) I'm realizing how much I really like the features, versatility, and sound of this amp. At the same time, I'm wondering why didn't I just build this as a higher-wattage amp with a built-in attenuator (or maybe just a Type II MV control) so that it could be *the* amp I could use for gigging and at home practicing? Nothing crazy loud, but something between 15 - 25 watts.

The amp uses higher voltages on the pre-amp tubes like bigger amps. I'm simplifying, but would it just be a matter of increasing the power & output transformers (I guess probably the choke too ... and maybe the filter capacitors)?

I can't remember which one of the good amp techs on YouTube it was (watched his video a while ago) but he was basically trying to tell people not to spend $ on a micro amp and just play the amp you gig with at lower volume levels. At the time I questioned that, but now am coming around to that idea. Granted, a number of the micro amps available on the retail scene truly don't sound that great in comparison to Rob's great schematics.

Here's my herd of self-built hand-wired amps so far (Bassman/JTM45 Micro on the top of the stack):

IMG_1416.jpeg
 

jtcnj

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The ability to crank the power section at reasonable / household volumes is the main attraction, to me at least. My EF80 JCM800 micro still pretty darn loud.
15 - 25 watts is crazy loud in my house.

My @5w 5F1 champ, especially when pushed with a boost or OD is pretty darn louder.
I'm only a home / hobby player so the gigging option isn't an issue for me.
 

King Fan

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Exactly. We can’t fall into the 'all-purpose amp' trap. You can’t ask your Vespa — or your 125cc Husqvarna — to make the Sturgis run. Micro by definition is for less power, distortion without earmuffs. Of course Rob has a nice video of a Micro Bassman gigging, but I bet a mic and PA were involved.

The guy who said ‘don’t build a micro, just turn down’ may not have been into distorted tone. Attenuators?? From nice distorted tone to household? I haven’t tried the >$1,000 kind, but I'm not sure putting a governor on your Hawg will make it groovy for runs down to Bleecker St. :)
 

joulupukki

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Ok, even a 5 - 10 watt would be great. I'm just saying this little guy has so much good tone it's a shame it's not capable of being just a bit louder and gig worthy. True, it could be mic'd up, but could you hear yourself over the rest of the band? I dunno. Just an interesting thought experiment going on here.
 

JohnnyCrash

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I’ve got a half a dozen 50 watt amps I built, but I’ve also got a half a dozen 5 watt amps too.

There are a few reasons for smaller amps:

For playing at home with a cranked amp sound that won’t make your ears bleed.

For recording. It’s nice to have different amps for different textures.

For fun. Small amps can be a great way to learn to build amps and don’t take up as much room as a full size amp.

Attenuators and master volume controls can squish the sound (not necessarily in a bad way), so sometimes a small non-MV amp provides a different dynamic touch.
 

JohnnyCrash

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Ok, even a 5 - 10 watt would be great. I'm just saying this little guy has so much good tone it's a shame it's not capable of being just a bit louder and gig worthy. True, it could be mic'd up, but could you hear yourself over the rest of the band? I dunno. Just an interesting thought experiment going on here.


Build its big brother version. One for home, one for the band/gig!

More amps is my motto :D
 

King Fan

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The wheels are spinning, for sure. Now that I have the proper PT in my 18w, I’m trying to plan what build to use the toroid PT I was using. Maybe the bigger brother to this one but still in a smallish head cab.

Have you looked at Rob's 6V6 5F6a notes? Even more output tube overdrive? Maybe a somewhat smaller PT, OT, rectifier? :)

And my brothers, though you may think we're stating the obvious (lol Andy), I hope this thread will be useful to builders early in their journey. You live in an apartment? have a baby? want some MV tone? Micro. Home recording studio in the spare room? Micro. Built a bunch of 5-20W tweed and BF amps (me), want an MV or two in the house? Micro. Have a bad back, good mic and decent PA? Micro. But if you just think a Micro is a cheaper or easier way to get you a 5F1 or 5E3 or 5F6a, read this...
 
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andrewRneumann

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Have you looked at Rob's 6V6 5F6a?

And my brothers, though you may think we're stating the obvious (lol Andy), I hope this thread will be useful to builders early in their journey. You live in an apartment? have a baby? want some MV tone? Micro. Home recording studio in the spare room? Micro. Built a bunch of 5-20W tweed and BF amps (me), want an MV or two in the house? Micro. Have a bad back, good mic and decent PA? Micro. Etc...

I read your post in the style of a speed rapper and it really cracked me up. Micro.

Seriously though, a thread filled with opinions about the virtues & faults of small amps is about the most common thread on TDPRI is it not?





…micro. 😜
 

King Fan

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I'm glad my micro contribution is getting some micro appreciation. :)

FWIW I'd suggest it may be neck and neck here between "my amp's too small" and "my amp's too big" -- but as you noted, Andy, Father Time and Lady Fashion have both been eroding the "big amp" shoreline for years. "Too small" is the new "just right."
 

2L man

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I have very long "todo" list but there is a micro amp or bigger bottle amp which also has one ELL80 noval double pentode and suitaple OT for it which use everything else what the other amp use.
 

Snfoilhat

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In the constant churn of content, a youtuber may eventually take every side in an argument to stay in the good graces of the algorithm. If the audience is full of people with the knowledge and means to build micro amps themselves, what exactly is this creator adding? Fatherly advice? Spend your money wisely? Turn that amplifier down!
Take it all w/ a grain of salt :)
 

Kev-wilson

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On the RobRob Deluxe micro there's a pre amp out mod, could similar be adapted for the Bassman too?

As a beginner I haven't a clue :p but love my micro amp :)
 

Lowerleftcoast

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Seriously though, a thread filled with opinions about the virtues & faults of small amps is about the most common thread on TDPRI is it not?

How do we reconcile the sound of a micro vs an attenuated macro? Neither at low dB sounds like the macro at stage volume. Which is better? Who's to say.

For me, the push pull pentode micros have an appeal but... I reason they will be too loud and still need attenuation for bedroom use. I would need to build a micro attenuator.

A @King Fan *micro* conundrum. hah.
 

King Fan

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For me, the push pull pentode micros have an appeal but... I reason they will be too loud and still need attenuation for bedroom use. I would need to build a micro attenuator.

Are there smaller power pentodes than EF80s? In my EF80 version, the Lar-Mar MV can take a *reasonable* amount of distortion down quite a few dB. Of course 'bedroom' depends a lot on your bedroom (and partner) acoustics, but I can easily play the Bassman Micro in my music room at comfortable listening levels. Baby sleeping levels, not so much. :)
 

joulupukki

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Have you looked at Rob's 6V6 5F6a notes? Even more output tube overdrive? Maybe a somewhat smaller PT, OT, rectifier? :)
Ah, I hadn't read through that. Thanks for pointing me there. Obviously I'm on the search for the target of a new build. More powerful 5F6a/JTM45, some sort of AB763 with 6V6 tubes, something else? Gonna keep letting it churn for a while.
 

RetiredUnit1

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"Why build a micro amp and not something a bit more capable?"

So if I understand the question correctly, you're feeling you should have built a larger amp first?

I think the best explanation is the way our brains work. When I looked at my first 5e3 I thought 'holy $#!+ that's a LOT of connections'. Now I look at it as "that's cute"

Lately, because I'm retired and don't have anything better to do, I've been drawing amps in visio. It's like building an amp but without all the soldering.

This is a bassman I drew with a couple of robrobs mods, and I rearranged things to suit my whims.... I am getting ready to cut the circuit board and swag the turrets, got the iron and chassis purchased....

5F6A 59 Bassman v08.2022.jpg
 




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