Your Preferred Amplifier Topology

[egellings]

I'm a tuber; slap me. My preferred power amp topology happens to be the circlotron (bridge) connection, with the tubes biased into class AB. My homebrew monoblocs use four EL34, or KT88's in the larger version (2 paralleled pairs) with 2 floating plate supplies in a bridge arrangement. Two smaller floating screen supplies are also required & deployed. Basically all 4 tubes are in parallel across the transformer primary. That allows me to have a lower turns ratio which can result in a better-performing transformer, which uses a so-called multi-filar winding technique, in which a ribbon of a number of wires is wound onto the core, and some wires in the ribbon become primary, while others become secondary. The selection of which wires in the ribbon are in which winding is the subject of a patent on this transformer. The resulting amplifier has low distortion and does not goop the tube sound on everything. Negative and positive feedback are used. Positive feedback comes from bootstrapping the driver stage. They tickle my nun-handles just fine.

 

[Plcamp]

Currently I am a class ab non surface mount amp fan of old stuff like my Adcom 535II and Haflers because they sound great and are trivial to maintain myself. (And I can always get another one cheap).

That said, I admit being a bit frightened for my budget if I happen to listen to a class d purify or hypex, from what folks here have said.

 

[Jimbob54]

Hi TK750,

I don’t mind and realize my above statement sounds like I am exaggerating. I have a 9.2.6 Atmos/DTS:X/Auro setup. I alike multichannel music in the morning and most of the day. Followed by Movies/Tv in the evening. So from about 0800 thru 2200 hrs my system is on and something is playing. Damn near every day 24/7/365. I am retired so this may make more sense. I use the hell out of my kit and apparently (reading what I just typed) I don’t get out much. In bed at night I use IEM’s to sleep with.

Other than the occasional headphone use and the IEM’s in bed. The above is all in one room. I hope this helps further explain my sickness…….

I'm intrigued by this. I've never tried, nor do I have the kit to play, multi ch music. But what genres of music are produced in m ch frequently enough to get multiple days of listening from? Or is your kit turning stereo into multi ch?

 

[AdamG]

I'm intrigued by this. I've never tried, nor do I have the kit to play, multi ch music. But what genres of music are produced in m ch frequently enough to get multiple days of listening from? Or is your kit turning stereo into multi ch?

Hi Jimbob54,

Amazon and Tidal have a fairly large and growing number of multichannel/atmos/3d mastered and remixed music in many genres. In addition my AVR can upsample 2 channel into various multichannel formats I choose. My general favorite for up sampling 2 channel is Auro 2d. I have found I prefer different Codecs for different genres. Auro for Classical and Choral. DTS:X for Jazz and Blues and some Bluesy Rock. Old school Rock 60’s and early 70’s good old 2.2 channel or Dolby upmix with center spread engaged. Part of the fun is the journey of trying different upmixers. For Femal Voices I love the expansive wide stage presentation of Dolby up mixing using Wides and 4 heights. Church Choirs and harmony vocals are sublime with DTS up-mixed and 6 heights. I have curated some specific Playlists just for this purpose.

 

[AdamG]

Ah very interesting! Thanks for the response, it sounds like you are making the most of your retirement which can only be a good thing. I hope one day I will be able to report similar numbers!

Just don’t wish for that time to come sooner. It’s not all popcorn and candy canes.

 

[iMickey503]

I'm a tuber; slap me. My preferred power amp topology happens to be the circlotron (bridge) connection, with the tubes biased into class AB. My homebrew monoblocs use four EL34, or KT88's in the larger version (2 paralleled pairs) with 2 floating plate supplies in a bridge arrangement. Two smaller floating screen supplies are also required & deployed. Basically all 4 tubes are in parallel across the transformer primary. That allows me to have a lower turns ratio which can result in a better-performing transformer, which uses a so-called multi-filar winding technique, in which a ribbon of a number of wires is wound onto the core, and some wires in the ribbon become primary, while others become secondary. The selection of which wires in the ribbon are in which winding is the subject of a patent on this transformer. The resulting amplifier has low distortion and does not goop the tube sound on everything. Negative and positive feedback are used. Positive feedback comes from bootstrapping the driver stage. They tickle my nun-handles just fine.

DAMN!!

​

 

[TheBatsEar]

That sounds like assumptions from someone who's never actually repaired them, or has skill for one but not the other.

Yeah, can't deny it, maybe i'm talking a bit out of my butt when it comes to class D.
I yield to your experience of one repair.

 

[mhardy6647]

<Marky thrusts his hands deep into his pockets, looks down and shuffles his feet. Softly, he mumbles:>

"Class A"

Move along.
Nothing to see here.

 

[forss]

Seems that class A/B and D are very popular and enjoyed by many

 

[tomtoo]

Seems that class A/B and D are very popular and enjoyed by many

Class a/b was mature more than 40 years ago. Class D is not so long mature. But today it is.

 

[SIY]

Class A/AB/B/D/G/H are not topologies.

 

[egellings]

Class D amplifiers can work just fine, but they are very tricky to implement and this difficulty makes them pretty much off limits to the home constructor, beyond buying modules and mounting them in boxes with power supplies. I don't really call that building an amplifier from scratch. Class AB in tube or semiconductor is much more approachable by the homebrewer. Class A is wasteful of energy and is entirely unnecessary in an output stage.

 

[Nonick]

Class NoTweeterHiss.

 

[egellings]

Class A/AB/B/D/G/H are not topologies. Correct. They are biasing schemes.

 

[mhardy6647]

Class A/AB/B/D/G/H are not topologies.

derp. OK. point taken.

Let's review the design topology of this circuit. It is a 2-stage resistance coupled amplifier using a 6SL7 - a hi-gain [mu], lo-transconductance [gm] dual triode as the input/driver tube capacitor coupled to the grid of either a 45 or 2A3 power triode operated in cathode bias...

JE Labs Simple 45/2A3

jelabsarch.blogspot.com

 

[tomchris]

Besides Class A/B or D. I am looking forward to topology improvements using GaN (Gallium Nitride) power transistors.

 

[Holmz]

Without talking about speakers, it seems a bit one sided.

For instance I would likely consider using a different amp on a hard to drive low impedance speaker than I would on say a compression driver.

 

[forss]

Besides Class A/B or D. I am looking forward to topology improvements using GaN (Gallium Nitride) power transistors.

What would be the improvements with these transistors ? ( GaN (Gallium Nitride) power transistors.)

 

[egellings]

No need for them in class A or AB type designs. They shine in switchmode applications, though.

 

[tomchris]

What would be the improvements with these transistors ? ( GaN (Gallium Nitride) power transistors.)

Well, you have GaN transistors and SiC MOSFETs both promising higher efficiencies, faster switching speeds, less dead time, high breakdown field etc. - all in a smaller package. But frankly, if it takes 10 years for the market to mature, and we have to endure tasteless audiofool novelty jewellery, then forget it.

I just wish for a small and efficient solution around 100W with the ability to double down to 1 ohm