Class A Amplifiers - who has one?

sunvalleylaw

Addicted Member
I am still kinda a newb and am getting my first components that are not a consumer grade receiver.

I ended up buying one and it is on the say. A Music Hall Mambo, solid state, Class A, 50 per side.

I don't know much about this type of amp, but it sounds good. Wanting to learn more, and see who else has Class A amps of various types, and also get any tips on care and feeding, etc. I do know to let it have lots of space to let the heat dissipate. But not sure how long to let it warm up, etc.
 
I am still kinda a newb and am getting my first components that are not a consumer grade receiver.

I ended up buying one and it is on the say. A Music Hall Mambo, solid state, Class A, 50 per side.

I don't know much about this type of amp, but it sounds good. Wanting to learn more, and see who else has Class A amps of various types, and also get any tips on care and feeding, etc. I do know to let it have lots of space to let the heat dissipate. But not sure how long to let it warm up, etc.

Here is a review of the amp by 6moons:

6moons.com/audioreviews/mambo2/mambo2_2.html


Myself, I built a 2A3 vacuum tube SET amp. 5wpc works well with a pair of Klipsch LaScala speakers.
 
Here is a review of the amp by 6moons:

6moons.com/audioreviews/mambo2/mambo2_2.html


Myself, I built a 2A3 vacuum tube SET amp. 5wpc works well with a pair of Klipsch LaScala speakers.
Yeah I saw that review. For my purposes, it will be a step up in power for my old Dahlquists.

Your little unit sounds very cool. I own two guitar tube amps, a 1961 Fender Concert, which has a Mercury Magnetics (not original) OT that looks very much like one that appears on the Dynaco ST-70, along with its 2 old Tungsol 6L6WGB tubes and 6 12ax7 preamp tubes (also tung sol, but one or two is getting microphonic so the set will probably get replaced). Not sure what the smaller, but sold little Peavey Classic 30 has in it off hand. I would like to have a tube amp up on my shelf in my office driving some speakers someday.

My new little solid state should do nicely in my TV/music room.

As I had really never considered amplifier class, or tube amps other than for guitar before, I was frankly unaware of class, particularly in stereo gear. Wanting to learn more now. Also, to learn more about my tube guitar amps that I have just had maintained, and played, up to now. I was aware I could mess with different tubes, but up til now when one of the pre-amp tubes in the Concert has started going microphonic, I had really no reason to change, as I was pleased with the sound and tone.
 
A class A amp keeps the transistors on or in the active range throughout the entire sine wave (or audio spectrum). That means they run hot and are less efficient than class B which uses one transistor to handle the lower part of a sine wave, and another to handle the upper part. In class B the transistors are "off" during half the cycle. Because class B switches transistors on and off they introduce a very small amount of distortion which is undetectable by any human being. Most amps are a mix of both technologies and are referred to as class AB.
 
A class A amp keeps the transistors on or in the active range throughout the entire sine wave (or audio spectrum). That means they run hot and are less efficient than class B which uses one transistor to handle the lower part of a sine wave, and another to handle the upper part. In class B the transistors are "off" during half the cycle. Because class B switches transistors on and off they introduce a very small amount of distortion which is undetectable by any human being. Most amps are a mix of both technologies and are referred to as class AB.
Yes, I have watched a lot on youtube and done other research and figured that part out. This guy's video seemed pretty good to me by way of a basic explanation. For now, I have already picked a solid state amp that will carry that inefficiency, and made my compromise.


Just interested in who hear uses Class A stuff, what they find is good to do in terms of care and upkeep, both tube style and solid state, etcv.
 
My Yamaha R-9 receiver has an Auto Class A mode that plays in class A for the first few watts then switches to AB when more power is required. I must confess that I don't hear a difference with class A on vs. off. I do notice the amount of heat coming off the unit though and I use Class A in the winter to help heat my listening room which can be a little chilly.
Class A really warms things up and can be hard on some of the chips in the unit. I have noticed drop outs in the turner section from time to time in that mode. You won't have this issue.
 
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British Fidelity A100 here.

Give it plenty of space, and clean it out frequently, as the high heat output creates a strong convection process, drawing dust into the case.

Mine sounds better after running for 20-30 minutes.
 
I built and use a 300B single ended tube amplifier I really like. A whopping 6wpc. I repaired a Technics "New Class A" amplifier I thought sounded very good. The topology is rather intetesting.
 
I have 4 Krell KMA 160 monoblocks that I use to drive my Kappa 9's. 160w each @ 8 ohms, and pure class A SS goodness--and they "double-down" to 1280w each @ 1 ohm. BUT they weigh just under 100 lbs each, draw 8A current each at idle and can heat a room pretty well. They sound their best after at least a half hour of "pre-heating" time at idle.
 
M22, I think (Series 20). Beautiful amp, altho I always thought that the front-mounted speaker terminals were a bit funky.

Very rare, very pricey, very cool.
 
My experience with Class A is limited to a Technics SA 510 receiver I bought new which became extremely hot at very low output or idle; cooler when playing at normal levels. I wasn't comfortable with the situation so I returned it for something else.
 
M22, I think (Series 20). Beautiful amp, altho I always thought that the front-mounted speaker terminals were a bit funky.

Very rare, very pricey, very cool.
I considered one, but they have a lot more 'stufff' in them then the Pass Labs diy projects.
 
I've a Chi-Fi JLH 1969 Hood amp.... Use it for my computer audio. Used to have a Chi-Fi Quad 405 copy through that has since been replaced by a Chi-Fi darTZeel NHB-108 copy.... My understanding is its class AB though it runs very hot also and heats up the entire room quite a bit. Pretty similar heat output to my class AB tube amp with a quad of KT120's installed.

Yeah, every single one of my amps a Chinese. That's about it though. Everything else in my various systems come from somewhere else. Except speakers. They make some great speakers.
 
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