ATC and tube amps

[yogibear]

Well the tube world is simple in construction as you have to deal with a grid or two, a cathode and an anode. Heaters could be indirect or direct (a sign of potential troubles ), however these very tubes are fantastic creatures. They can be strapped in N number of ways and actually take you on long and wide “roller coaster” rides. To understand them well for audio applications, there are no shortcuts and hands on experience makes you start understanding them and still the whole picture isn’t as rosy as it seems but it’s very rewarding once you start getting a hang on them.

However biasing of tubes itself doesn’t make them sing linear but it’s the team work of tube biasing plus your output iron which makes the whole difference. Specs of output must be clearly spelled to help you bias your tubes ideally, provided your power supply is ready with all the juice needed.

I like to operate tubes at 70%-80% of the maximal operating voltages and 50% of maximal current, for long tube lives and optimal sonics.

The impedance of your speakers and the right output tap it’s connected to your amp is vital but don’t shy to experiment. Mostly it’s a vacillation between the 4 and 8 ohms. It’s quite wise to take DCR reading of your speakers including the whole speaker cable length as that’s the actual impedance the tube amp sees. However the loophole is, how much DCR your multimeter reads when the leads are shorted. There you need to do the math and get a fair idea. And it’s just a DCR as a starting point and not a reflection of your speaker impedance dips but it still helps.

Distortion and hum are two big enemies of tube amplifiers and must be taken care of. In music, there is no place for them.

Just sharing a bit of my experience and journey…

 

[Yogesh]

They things we endure, the lengths we go in pursuit of spectacular sound is amazing and probably ridiculous to those immune to such temptations.

They are the cursed ones who are the blessed ones!

 

[reignofchaos]

They are the cursed ones who are the blessed ones!

Those who are far far away from this wallet crushing hobby haha.

 

[AP@1992]

Audio Space uses ATC speakers in their factory to test their amps. They are very popular in Japanese audiophile community. I like everything about this amp. Such a neat and powerful sound. My Tannoys however do better with drier sounding tubes like KT88 and DHTs. Else I would have been all set for good 5 years. I only wonder how special it will sound with a set of NOS Mullard EL34s

after living with the NOS Mullards (specially the XF2), I can say it sounds magical but it won't serve every genre of music. It's wonderful at everything except where bass definition and bass articulation is not the main requirement. For everything else it is unrivalled and shall remain so.

The US made 6CA7 NOS, will retains some of the this magic character with livelier sound and better base, but that big FAT larger than life sound of Mullards XF2 is unrivalled in my opinion.

 

[AP@1992]

Happy to read your findings

I would encourage to under bias the amp by atleast 20%. In my case, the recommended bias for EL34's is 380 mv. And I keep them at 320 mv or round abouts. I find that it makes the sound more richer / lusher, even with negative feedback set at zero.

And pay no attention to folks who point out the distortion. The best speaker's bass drivers distort upto 3%, not to mention the mundane ones. So even a 1% distortion at the amps is less than the speakers .

For most real world speakers, not to mention very high efficiency ones, EL34 is probably the closest we can get to the elusive 300B seduction. Happy to know you discovered the magic. Enjoy

Edit : I have'nt tried many tubes. Probably only Electro harmonix and JJ. And I find the JJ to be richer and fatter in the mid range, though EH sounded a bit more extended in the treble I think. Of course the input tube matters too. I moved from EH to Gold lion, it improved the clarity a bit I think. The shift was a few years back, so not really sure about my findings now.

With great respect, I find that EL34 and 300b, are actually very different sounding. Exceptions are there.

EL 34 has great texture, smooth midrange and a very coloured thick sound. This is a common feature of all most all EL 34 tubes however some does it better than other.

Except for a very few 300b tube (Genelex comes to my mind), the general character I found is a clean, distortion and grainless sound which is mellow and has a better sense of air and dimension. It's smooth, but cleaner.

 

[reignofchaos]

So the GE 5751 tubes were absolutely new. They have now settled down. While these have slightly lower gain than the 12ax7 tubes used by default, now they are sounding totally fantastic. So much micro details and inner texture compared to the stock tubes. I am loving it. The tone is much much more natural than the active SCM 100 with ATC's own amp packs that I tried at my place. Dynamics of course are a different kettle of fish - the 100 was absolutely bombastic in comparison. However the 19 is absolutely no slouch.

 

[Yogesh]

They things we endure, the lengths we go in pursuit of spectacular sound is amazing and probably ridiculous to those immune to such temptations.

https://www.howtogeek.com/being-an-audiophile-is-a-curse-not-a-blessing/

 

[sajeet]

On the heat issue: I gave up on the Lampizator (Tube DAC) after several months of enduring the heat. The SQ was lovely but the physical discomfort was too much after half an hour of listening. AC was not an option in that room for some reasons. Reluctantly moved on.

Sir, in Chennai, heat emitted from Big7 Dac iwith 300Bs is not causing discomfort, may I know the model, of course, I do agree that proper ventilation is mandatory