Compact ~20WPC Tube Amp

Hey guys, we all know that you both build great products. Deep respect for Atmasphere and Aric Audio

Agreed. No question there is more than one successful approach to building audio components. And the final product will speak for itself.

Charles

@aricaudio 

I much appreciate your informed reply. I continue to learn from forum knowledgeable participants such as you and Ralph (atmasphere).

Charles

@carlsbad 

The best amp I've ever heard uses 6sn7 to drive 6c33c.  

I believe you. The 6SN7 is a renowned tube. As with anything the key factor is application,design and implementation. I understand there are many roads that lead you to Rome.Inevitably different builders will use various approaches.

Charles

@atmasphere 

The funny thing is you could execute this with the same number of tube sections as used in a traditional SET right now (three total, including the power tube). The reason you don’t see this is the fact that you have to build a negative power supply. But if you did, you could build an SET that was inherently lower distortion which means it would be more transparent.

Interesting you say “more transparent “. ironic then, one of the first things I noticed when I heard my 300b SET mono blocks, superb transparency and startling nuance/inner detail. As if the speakers weren’t even in the room!

I do not possess the technical background or expertise  to explain why this is exactly  so. I can only rely on what I hear. That initial  listening encounter was striking!

Charles

@atmasphere 

I am not an electrical engineer. I do listen intently when people who are successful at what they do offer their perspective and experiences. Israel  Blume is very accomplished with what he does and so is Aric. They both share the same opinion with regard to appropriate driver tubes for DHT tubes (Specifically 300b).

Either of them (And other amplifier builders who have similar view) are far more qualified than me to debate this point with you. I can say that their comments make plenty of sense and are backed up by their SET amplifier performance results. I just listen and read in an attempt to learn.

Charles 

Definitely planning to contact Aric!

Good idea! 😊

Charles

@aricaudio 

With most SETs the driver is the amplifier’s downfall- not the power rating of the amp, or the 300B.

Aric this is precisely what the builder of my Coincident SET (And speakers) explained years ago. The main limitation with some SET amplifiers is the choice of weak/inadequate driver tube. Just as you say, this driver needs to be robust. The DHT output tube demands this. He chose the 6EM7 rather than the 6SN7 for that reason.

@atmasphere 

Good advice you gave to Israel Blume (Coincident). I’m happy that he took note of that wise counsel,😊

As you’ve pointed out before, higher speaker impedance means less amplifier stress/work and less distortion.

Charles

@atmasphere

Based on your comments your speakers are nowhere near efficient enough to work with your SET.

Which leads me to suspect that the 96 db sensitivity rating is exaggerated or (More possibly) the speaker’s impedance curve and load just isn’t suitable for an SET 300b.

My speakers are 94 db but a 14 ohm impedance with an appropriately designed/damped woofer to not require much amplifier DF (Damping Factor). They literally sing with my 300b SET mono blocks and replaced the previous 100 watt amplifier.

So, much depends upon speaker design and intended use.Push pull tube amplifiers will usually have lower output impedance and thus higher DF. Also generally they utilize some degree of NFB which increases DF.

Most SET amplifiers are zero NFB (Or very low) and will require different/compatible speaker loads. OP’s speakers just need a good quality push pull amplifier and they’ll do well.

Charles

@dhcod 

With your budget you leave yourself with good flexibility in choices. I agree that Quicksilver amplifiers merit attention. I’d give Aric Audio a call/email. I believe that he could build a really nice quality amplifier within your price range. You’re in a good position with new and certainly used possibilities.

Charles

@dhcod 

Do you have a price range limit ?

Charles