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

SerpentRuss

Tele-Holic
Joined
Feb 17, 2021
Posts
578
Age
59
Location
North Carolina
I'm beginning to think the definitive, scalable tweed Bassman project might be to build a Bassman head with 6V6 output tubes using the original 2 ohm output transformer. Then put a switched 8 ohm power resistor on each of the four parallel speaker jacks. Pair that with a 4 speaker cabinet with four jacks and manage power by adding and subtracting speakers.
 

Bitsleftover

Tele-Holic
Joined
Oct 17, 2016
Posts
699
Location
The North of England
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.
I totally agree.
I had to build a John DH attenuator for my micro. And because of the non linearity of power / perceived volume we discuss at length, it takes almost as much attenuation to get my micro at a family friendly volume as it does a much larger amp. But I still feel a micro amp attenuated down to that level sounds better than a big amp attenuated down to that level. And better than any big amp with a Master Volume set to virtually nothing. But that’s just my humble opinion.
 

Back at it

Tele-Meister
Joined
Apr 10, 2021
Posts
367
Age
70
Location
Denver
It ain’t cheap but a Fryette power station fixes both too loud and not loud enough. It adds another box to your chain but also gives a very nice fx loop

with the impedance matching it pretty much works with any amp/ cab combination
 

ahiddentableau

Tele-Holic
Joined
Jul 8, 2018
Posts
865
Location
Middle of Nowhere
I mostly agree with you. My problem with the 2 watt amps is that they're still too loud to truly crank in my space. If I had a different living situation it would probably be different.

To be clear, my complaint isn't that low power amps aren't useful. It's that the micro amps aren't micro enough for my needs. I need one that is going to be another 10dB quieter, at least. Probably more.
 
Last edited:

Robnik33

TDPRI Member
Joined
Aug 21, 2021
Posts
49
Age
56
Location
NorCal
How about adding a master volume? I have a Wayde Audio 50W dual 6L6 with a very well executed master volume that I can play at any level with as much or little distortion as I want. I also built a Robinette Princeton Reverb delete 6V6GT and added a pre phase inverter master volume and midrange control. Same result, dial-a-distortion at any volume level. This one only weighs 27 pounds with a 12" speaker. Why would I need a micro amp?
 

cometazzi

Friend of Leo's
Silver Supporter
Joined
Dec 3, 2019
Posts
2,198
Location
Wisconsin, Das Land von Käse und Bier
Anecdotal experience here:

I've built two micro amps: a Heavy Watter, and something I call the Black & Tweed, which is a two-channel amp. The latter has a Tweed Princeton 5F2-A as one channel, and a Blackface Champ as the other.

I've also got an attenuator and I use it on such things as a Marshall 18W clone, a 50W JCM800, a Laney AOR 30 and Vox AC-15.

I live in an apartment, and it doesn't take much to register a noise complaint. Also, I like to play guitar at what I consider a 'reasonable volume', not one that is crushingly loud.

The 'real and more capable' amps without an attenuator are incredibly difficult to dial-in at a useable volume that is not too loud. Using an attenuator helps, but it also sucks the tone out of the amps and makes them 'dull and sterile' sounding.

By contrast, the micro amps are 'just right' when it comes to power. IME, halfway up on the volume is where I want to be, and at that level the tone is great. They're just the right amount of volume to fill the room, and jam and reasonable volumes electrically or with someone playing an acoustic guitar and singing. There's a whole lot of adjustment in the volume to get it just right within that range.

Even if I weren't in an apartment, I would want to play guitar at about this level. "Stupid Loud" which is capable with most of the amps I mentioned above (especially the JCM) just does not appeal to me. Meanwhile, every micro amp I build also has a post-OT line-out with a volume control. In theory I could send the signal to a bigger amp and have the micro sound at huge levels.

But for the most part, I'm very content at playing guitar in a 1W or 2.7W amp. I'll save the big stuff for the stage (if that ever happens again) but aside from a 5E3 clone, just about every amp I plan to build is likely going to be a micro version of something, or something I conjure up myself as a micro amp.

YMMV
 

NTC

Tele-Afflicted
Joined
Mar 17, 2003
Posts
1,303
I'm beginning to think the definitive, scalable tweed Bassman project might be to build a Bassman head with 6V6 output tubes using the original 2 ohm output transformer. Then put a switched 8 ohm power resistor on each of the four parallel speaker jacks. Pair that with a 4 speaker cabinet with four jacks and manage power by adding and subtracting speakers.

With a 5F6A OT and 2 6V6's, the standard load should be 4 ohms - either 2x 8ohm speakers or 4x 16 ohm speakers.
 

joulupukki

Tele-Meister
Joined
Nov 26, 2020
Posts
432
Location
Utah
Very wise words @cometazzi. Thanks for sharing. I had a couple of players over tonight and the micro was definitely loud enough in that situation (all of us playing guitars).
 

owlexifry

Tele-Meister
Joined
Feb 10, 2021
Posts
354
Location
Adelaide, Australia
my 2c:
many people conflate amplifier output and speaker movement as the same issue.

i assume people say most amps sound best turned up to "stage volume", because:
- the power tubes are "going harder", approaching saturation, and possibly distortion.
- the phase inverter stage(s) - getting more saturated from a hotter input

obviously these factors affect non-MV amps a lot more than MV amps.

My experience with using a good attenuator/reactive load (fryette power station 100) has given me some insight into this issue (at least with MV amps)

It's not all about getting the power amp or the phase inverter cooking (perhaps for non-MV amps it is, i'm not sure, I haven't played one)
in my experience, it's more about getting the speakers moving air.

even with the one of the better reactive load box/attenuators on the market, you can crank the MV all day long, but if the overall output to the speakers allows them to run quieter, at 'bedroom practice' level, it is not going to sound anywhere near as good as the same speakers getting cranked to stage performance volume. (regardless of wherever the MV is set).

this is why i'm currently planning to build an oversized closed back 1x12 cabinet - so i don't have to use a 4x12 for bedroom use anymore...

my theory is (stop me if i'm wrong here):
- a 1x12" speaker cabinet, is going to run hotter, and hence 'sound better', than a 4x12" cabinet, given the same 'low output' signal from an amplifier/attenuator, for the purpose of low volume 'bedroom use'.
(because that single 12" speaker is going to get driven a lot harder than the same signal distributed over four 12" speakers.... is that right? or have i cooked the goose here?)
 

Lynxtrap

Tele-Afflicted
Joined
Feb 29, 2016
Posts
1,426
Location
EU
If you have a sound system when playing live you can always mic the little thing and put it through the main speakers and monitors.
 

telemnemonics

Telefied
Ad Free Member
Joined
Mar 2, 2010
Posts
34,484
Age
62
Location
Maine
my 2c:
many people conflate amplifier output and speaker movement as the same issue.

i assume people say most amps sound best turned up to "stage volume", because:
- the power tubes are "going harder", approaching saturation, and possibly distortion.
- the phase inverter stage(s) - getting more saturated from a hotter input

obviously these factors affect non-MV amps a lot more than MV amps.

My experience with using a good attenuator/reactive load (fryette power station 100) has given me some insight into this issue (at least with MV amps)

It's not all about getting the power amp or the phase inverter cooking (perhaps for non-MV amps it is, i'm not sure, I haven't played one)
in my experience, it's more about getting the speakers moving air.

even with the one of the better reactive load box/attenuators on the market, you can crank the MV all day long, but if the overall output to the speakers allows them to run quieter, at 'bedroom practice' level, it is not going to sound anywhere near as good as the same speakers getting cranked to stage performance volume. (regardless of wherever the MV is set).

this is why i'm currently planning to build an oversized closed back 1x12 cabinet - so i don't have to use a 4x12 for bedroom use anymore...

my theory is (stop me if i'm wrong here):
- a 1x12" speaker cabinet, is going to run hotter, and hence 'sound better', than a 4x12" cabinet, given the same 'low output' signal from an amplifier/attenuator, for the purpose of low volume 'bedroom use'.
(because that single 12" speaker is going to get driven a lot harder than the same signal distributed over four 12" speakers.... is that right? or have i cooked the goose here?)
Not sure how you mean not about getting the tubes cooking if you attenuate with the fryette so the amp runs loud but speakers get little of the power?

As for fewer speakers sounding better at low volume, I think yes if your sound is about old low wattage alnico mag small VC speakers falling apart ready to blow.
But modern higher power handling speakers shouldnt really deliver a different sound at low volume.
Of course four speakers is a little louder so one is a little lower volume at the same amp setting.

I run my 4x12 these days with a replaced back thats about half open (rectangular hole in the middle of a full size back, not just half a back) and only use one of the four speakers at a time.
If the back is closed, the other three become passive radiators!
For bedroom Id just run one speaker in the 4x12, not sure another cab will help much for the effort, unless you need it for other reasons too. And really no need for it to be big or to be closed back.
A Princeton size open back sounds great with a 12 or a 10 and makes sense if you need a smaller cab.
 

D'tar

Friend of Leo's
Joined
Jan 11, 2013
Posts
3,812
Location
WNY
To be clear, my complaint isn't that low power amps aren't useful. It's that the micro amps aren't micro enough for my needs. I need one that is going to be another 10dB quieter, at least. Probably more.

Mies van der Rohe: "Less is more."
Enter the Nano Amp!

1660834709544.png
 

SerpentRuss

Tele-Holic
Joined
Feb 17, 2021
Posts
578
Age
59
Location
North Carolina
With a 5F6A OT and 2 6V6's, the standard load should be 4 ohms - either 2x 8ohm speakers or 4x 16 ohm speakers.
You're right, you would need a different 2-ohm transformer. 6V6s into the original bassman OT with 4.1K primary and driving a 2 ohm total load would only give you about 2 watts. It might be a really interesting 2 watts, but you'd have to spend quite a bit to find out. I also like the 16 ohm option to keep four.

I still like the idea of a 2-ohm OT secondary and the possibility of switching in and out up to 4 speakers. Or maybe a 2.6 ohm OT driving up to three 8-ohm speakers. The bigger Hammond universal would work, but there may be better options. The highlighted yellow connection would work for four 8-ohms in parallel, perhaps one of the circled connections might work for three.

Four or Three Parallel 8-ohm Tranny.JPG
 

robrob

Poster Extraordinaire
Ad Free Member
Joined
Dec 29, 2012
Posts
8,633
Location
United States
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.
Coming soon! The RobRob Micro Attenuator! Is your micro amp too loud? Are you tired of your significant other yelling, "TURN THAT SH*T DOWN!" Then the RobRob Micro Attenuator is for you. It slices, it dices, it crawls on its belly like a reptile! You'll love the RobRob Micro Attenuator. Get yours before they're all gone!
Postage and handling not included. May cause scabies, hair loss and on rare occasions cause death and dismemberment. Do not taunt the RobRob Micro Attenuator. Your mileage may vary. Additional warnings and information at www.noonecares.com.
 

2L man

Tele-Afflicted
Joined
Nov 23, 2020
Posts
1,594
Age
62
Location
Finland
I still like the idea of a 2-ohm OT secondary and the possibility of switching in and out up to 4 speakers.
if you are willing to use resistors to dissipate most of the power you can first connect four 8 ohms speakers two parellel and then series for 8 ohms and they get 1/4 the power. Then all four speakers series to 32 ohms and loudspeaker power drop to 1/16.

I have run 16 ohm speaker on 4 ohm output and have 20 ohm resistor on 16 ohm output and sound is better than what L-pad attenuator use produce. I think its because loudspeakeaker still act some kind of "reactance" although 20 ohm resistance does not and will dampen spesker effect because it is in same secondary coil.
 
Last edited:

Lowerleftcoast

Poster Extraordinaire
Joined
Dec 30, 2019
Posts
5,744
Location
california
Coming soon! The RobRob Micro Attenuator! Is your micro amp too loud? Are you tired of your significant other yelling, "TURN THAT SH*T DOWN!" Then the RobRob Micro Attenuator is for you. It slices, it dices, it crawls on its belly like a reptile! You'll love the RobRob Micro Attenuator. Get yours before they're all gone!
Great! I'll get the handy two pack with the complementary travel size mini-micro Attenuator in Popeil blue.
 

joulupukki

Tele-Meister
Joined
Nov 26, 2020
Posts
432
Location
Utah
@robrob Out of curiosity, you've had experience with both the 12AU7 and EF80 versions of the Bassman Micro. Do you notice either one being louder overall volume dimed vs. the other? More clean headroom in one vs. the other? Curious minds (ok, maybe just me) want to know. I should have had us do that comparison when @King Fan and I had our two amps together.
 




Top