300w Pure class A Monoblock search!

[dlaloum]

Presumably, the factors would be quite dramatically different for an electrostatic speaker, or for ribbons, etc....

 

[Axo1989]

Stuff accumulates over time, what can I say?

Looks like we employ the same cleaner.

So those fabulous, clean impulse and envelope graphs from your MLs come from there ... truth is sure stranger than fiction.

 

[Axo1989]

Late to this thread, but one of my minor waking audiophile dreams is to get my hands on a pair of big Krell Evolution monoblocks and ditto of say March 501s along with that comparator box plus some mad giant passive speakers with subzero impedance in the bass and blind test the sh*t out of them. I should throw in some 'stats with tragic impedance in the treble for good measure. Donations accepted.

 

[RayDunzl]

Late to this thread, but one of my minor waking audiophile dreams is to get my hands on a pair of big Krell Evolution monoblocks

Some Krell 400e Monoblock build pictures

 

[Axo1989]

Some Krell 400e Monoblock build pictures

Great photo sequence.

I've heard and passed on a pair of 400 monos (not the e version) basically lacking the requisite AUD $25K in loose change. It's good to see your money's worth in sheer mass and very orderly complexity. Damn. I'll likely settle for a more affordable/practical 302e as there are a few floating around. They have a nice mechanical symmetry that the 402e lacks which somehow assuages my desire for monoblocks. Also tempted by a pair like yours that showed up in Melbourne recently for a similar price (to the 302, not the 400 pair). I'm keen on the e-series 2 watt standby though.

Edit: for the OP's purposes those late classic Krell stereo amps come up around USD$5K now so still over-budget, you have to go back to earlier versions to get closer.

 

[Ncesar]

Maybe this os an option?
https://www.audiophonics.fr/en/powe...-power-amplifier-stereo-class-a-2x300w-8-ohm-

 

[antcollinet]

Maybe this os an option?
https://www.audiophonics.fr/en/powe...-power-amplifier-stereo-class-a-2x300w-8-ohm-

Page not available

 

[dlaloum]

TONEWINNER AD-1PA Power Amplifier Class A Stereo 2x300W 8 Ohm - Audiophonics

Powerful Class A stereo power amplifier, the Tonewinner AD-1PA benefits from a high quality balanced architecture that allows it to develop significant power while ensuring a dynamic and precise sound reproduction.

www.audiophonics.fr

 

[Thorsten Loesch]

TONEWINNER AD-1PA Power Amplifier Class A Stereo 2x300W 8 Ohm - Audiophonics

Powerful Class A stereo power amplifier, the Tonewinner AD-1PA benefits from a high quality balanced architecture that allows it to develop significant power while ensuring a dynamic and precise sound reproduction.

www.audiophonics.fr

The page claims:

Pure class A output power

100W @ 8Ω

The circuit on the page shows 250mA quiescent current. This is not possible "per device", my calculations suggest 100mA per device.

But even if we accept 250mA per device, this is 1A quiescent current per block of 4 output transistors and hence 2A maximum output current before the Amplifier leaves Class A and becomes Class AB.

Now with 2A peak we get 1.414A RMS and with 8Ohm load 1.414A RMS current means the Amplifier will deliver 16W in Class into 8 Ohm, 8 Watt into 4 Ohm and 4 Watt into 2 Ohm.

Thus it is ABSOLUTELY NOT a 300W Class A Amplifier. Nor is it a 100W Class A Amplifier.

It is a 300W Class AB amplifier, with a greater amount of Class A power than an optimum bias Class AB Amplifier using the exact same parts (that would be 0.72W Class A into 8 Ohm).

Additionally the Amplifier uses the kind of output stage that is more or less the worst case for thermal bias modulation and thus thermal memory distortion. Extra Class A bias will mitigate that and overall the product is likely a decent enough amplifier.

But advertising it as 300W Class A Amplifier is plain and simple false advertising.

Thor

 

[pma]

Now with 2A peak we get 1.414A RMS and with 8Ohm load 1.414A RMS current means the Amplifier will deliver 16W in Class into 8 Ohm, 8 Watt into 4 Ohm and 4 Watt into 2 Ohm.

If it was push-pull class A with 2A idle current, it would give 64W/8ohm, or 32W/4ohm, or 16W/2ohm in pure class A.

 

[Thorsten Loesch]

If it was push-pull class A with 2A idle current, it would give 64W/8ohm, or 32W/4ohm, or 16W/2ohm in pure class A.

But it is push-pull with (according to notes on schematic) 1A idle current (4 X 250mA), hence 16W/8R and in my estimation the circuit cannot run at 250mA per transistor, only ~ 100mA per device.

Thor

 

[pma]

But it is push-pull with (according to notes on schematic) 1A idle current

OK. Then no objections

 

[pkane]

Only 200W of class A, not quite up to the OP specification, as well as breaks the budget (and is no longer made). But doubles as a very efficient room heater:

Pass Aleph 1.2 monoblock power amplifier

We all have biases. The trick is knowing your biases so they don't get in your way. Mine are pretty obvious. I don't like "fussy" gear that demands special care and feeding. I'm lazy—I want to just turn stuff on and begin listening. Perhaps that's why I have a positive bias toward Nelson Pass's...

www.stereophile.com

 

[Sokel]

Only 200W of class A, not quite up to the OP specification, as well as breaks the budget (and is no longer made). But doubles as a very efficient room heater:

Pass Aleph 1.2 monoblock power amplifier

We all have biases. The trick is knowing your biases so they don't get in your way. Mine are pretty obvious. I don't like "fussy" gear that demands special care and feeding. I'm lazy—I want to just turn stuff on and begin listening. Perhaps that's why I have a positive bias toward Nelson Pass's...

www.stereophile.com

^
Karita likes this

 

[pkane]

^
Karita likes this

When idling it feels hot enough to be uncomfortable to the touch. I suspect Karita may not like to be on top of one of these

 

[fpitas]

When idling it feels hot enough to be uncomfortable to the touch. I suspect Karita may not like to be on top of one of these

From what he has said, he plans for the heat sinks to run about 50C with only natural convection. I put some quiet fans on my J2.

 

[Sokel]

When idling it feels hot enough to be uncomfortable to the touch. I suspect Karita may not like to be on top of one of these

I'm not so sure about it,ishe was climbing my Audio Analog anniversary as a kitten (she was probably trying to forget the cold days as a stray kitten) and I'm sure she got sad when I sold it .

 

[pkane]

From what he has said, he plans for the heat sinks to run about 50C with only natural convection. I put some quiet fans on my J2.

Mine have been running au naturel. Back in the 90's I used to leave them running all the time as I didn't want to wait an hour or more for them to come to their nominal operating temperature. I'm sure that I'm responsible for most of the recent global warming -- sorry everyone!

 

[Sokel]

Mine have been running au naturel. Back in the 90's I used to leave them running all the time as I didn't want to wait an hour or more for them to come to their nominal operating temperature. I'm sure that I'm responsible for most of the recent global warming -- sorry everyone!

At least it was an amp,I helped with an electronic xover for some time.
Dual-mono with 2 15-0-15 "special" PSUs mounted on 30cm heatshinks.
Case was running 60° C at any given time as if I had some amp inside.
Good old days

 

[fpitas]

Mine have been running au naturel. Back in the 90's I used to leave them running all the time as I didn't want to wait an hour or more for them to come to their nominal operating temperature. I'm sure that I'm responsible for most of the recent global warming -- sorry everyone!

Did you hear a difference after them warming up? Maybe my ears aren't good enough, but with the J2 it sounds the same warm or cold.