I had my Silvaweld OTLs on my Acoustat 1+1 and it sounded heavenly...but hotter than hell!
OTL amp owners
- Thread starter bonzo75
- Start date
I had my Silvaweld OTLs on my Acoustat 1+1 and it sounded heavenly...but hotter than hell!
Although not fully class A - no true tube OTL of significant power can be class A when using your speakers - the MA-2 is biased at 1.2A - much more than common class A/B tube or SS amplifier. It is what was called a very enriched class A/B amplifier, most of time working in class A.
Why going for an expensive and hard to get tube (the 6C33) when you can use the well sounding, cheap, reliable and safe 6AS7?
6C33Cs are cheap and plentiful in fact.
You mean 6AS7 I think Ron. 6SN7 is a small signal tube (input and driver). Atmasphere uses the 6AS7. Einstein and Graaf also used 6C33C and are not lush sounding...
Yes, but unfortunately very unreliable, particularly for OTL's that ask for high peak currents. Graaf users (as me), know well about it.
I talked with Ralph today, and he was very patient and informative and very helpful. Ralph thinks that the sound of the Novacron and the sound of the M-60 are very similar. If anything, he said, the M-60 might be slightly sweeter on the top end.
He fully rejected my theory of any consistent sonic difference between 6C33C output tubes and 6AS7 output tubes.
I suggested to him that, since virtually everybody loves the crystalline transparency of OTL, there are only three possible reasons why not every tube-preferring audiophile in the world uses his amplifiers: 1) cost, 2) speaker incompatibility or 3) preference for the rounded, more bloomy sound of output transformer-coupled tube amplifiers, over the neutrality of Ralph's OTL amplifiers.
Ralph pretty much agreed with this and added that he simply has no interest in the warmer colouration imparted by output transformers.
He fully rejected my theory of any consistent sonic difference between 6C33C output tubes and 6AS7 output tubes.
I suggested to him that, since virtually everybody loves the crystalline transparency of OTL, there are only three possible reasons why not every tube-preferring audiophile in the world uses his amplifiers: 1) cost, 2) speaker incompatibility or 3) preference for the rounded, more bloomy sound of output transformer-coupled tube amplifiers, over the neutrality of Ralph's OTL amplifiers.
Ralph pretty much agreed with this and added that he simply has no interest in the warmer colouration imparted by output transformers.
Thanks Ron
Great feedback and summary
Maybe add, and heat is another issue, especially a lot of 6c33, and warm climates like Australia , having said that I am in Canberra where the heat is often welcome
......”
I talked with Ralph today, and he was very patient and informative and very helpful. Ralph thinks that the sound of the Novacron and the sound of the M-60 are very similar. If anything, he said, the M-60 might be slightly sweeter on the top end.
He fully rejected my theory of any consistent sonic difference between 6C33C output tubes and 6AS7 output tubes.
I suggested to him that, since virtually everybody loves the crystalline transparency of OTL, there are only three possible reasons why not every tube-preferring audiophile in the world uses his amplifiers: 1) cost, 2) speaker incompatibility or 3) preference for the rounded, more bloomy sound of output transformer-coupled tube amplifiers, over the neutrality of Ralph's OTL amplifiers.
Ralph pretty much agreed with this and added that he simply has no interest in the warmer colouration imparted by output transformers.”
Great feedback and summary
Maybe add, and heat is another issue, especially a lot of 6c33, and warm climates like Australia , having said that I am in Canberra where the heat is often welcome
......”
I talked with Ralph today, and he was very patient and informative and very helpful. Ralph thinks that the sound of the Novacron and the sound of the M-60 are very similar. If anything, he said, the M-60 might be slightly sweeter on the top end.
He fully rejected my theory of any consistent sonic difference between 6C33C output tubes and 6AS7 output tubes.
I suggested to him that, since virtually everybody loves the crystalline transparency of OTL, there are only three possible reasons why not every tube-preferring audiophile in the world uses his amplifiers: 1) cost, 2) speaker incompatibility or 3) preference for the rounded, more bloomy sound of output transformer-coupled tube amplifiers, over the neutrality of Ralph's OTL amplifiers.
Ralph pretty much agreed with this and added that he simply has no interest in the warmer colouration imparted by output transformers.”
This is incomplete imo as OTLs have other idiosyncrasies. See the common recommendation of Speltz autoformers in order to increase speaker impedance (which can't be 100% transparent of course). OTLs are often lacking in bass too. So is this complete neutrality? Not so sure.
Ralph's amps are third harmonic (as he will tell you) which is more "neutrality" to some. To those who prefer second harmonic it sounds lean. I don't think it's the OPT. Plenty of really good iron out there too.
I think needing to increase speaker impedance would be covered by 2) speaker incompatibility.
I was not aware OTLs are often lacking in bass. I certainly did not have that feeling with Danny's Einsteins driving Alexxes.
The third harmonic point is an excellent one and, in fact, Ralph said this himself. But no OPT tube amplifier I have ever heard approaches the clarity of the OTL I have heard. Why do you think it is not the OPT? Maybe it is the OPT supplemented by the second harmonic distortion of the SET?
If not the OPT to what do you attribute that incredible crystalline transparency of the OTL?
no transformer in the signal path = more transparency. but also = impending explosive tendencies and challenges in authoritative grip. so the better sounding (most refined) OTL's require speaker to match amp. not fit amp to preferred (already purchased) speaker. relatively authoritative OTL's exist......but are maybe not the most magically sounding ones.
so Ron, you need to fall in love with an amp and buy it, then find a speaker to match......not the other way around. unless you go with very easily driven speaker choices.
An OTL will not need bass in your system and a flat impedance ribbon will make an OTL relatively unstressed...same for a SET.
While it is true that SOME transformer coupled amps have sufficient iron, I would argue that most do not in order to be truly transparent. Once you clean that up a good SET sounds closer to a good OTL than to a "normal" SET or push/pull tube amp.
The best SET amps don't have this coloration that Ralph is averse to. You have to have seriously over specified iron to avoid saturation that leads to tubey colorations. Once you have done that they basically evaporate.
We must consider that OTLs have high output impedance and some speakers have very severe dips in the impedance in the bass frequencies - this can create dips in bass response. Some speakers are adequate for OTLs, some are not. XLF's are good candidates ...
As your speakers were designed by a SS amplifier designer that praises high current and low output impedance in his amplifiers I would not assume that they are OTL friendly. But they are specified at 6 ohms - a good thing considering all else in the brand are 4 ohm. It takes two minutes to carry the measurement of impedance using REW or Spectraplus...
I think the Einstein OTL amps sounds relatively normal with my brief exposure to them with their own speakers at Munich.
I have only ever heard Atma-Sphere amps once driving horns at Munich. I was freaked out it sounded so weird. The sound floated out with consummate ease and no bite whatsoever. Huge 3D soundstage type of presentation. Obviously seriously coloured.
I posted a video on YouTube of the Atma-Sphere set up a while back. Might post it later.
I have only ever heard Atma-Sphere amps once driving horns at Munich. I was freaked out it sounded so weird. The sound floated out with consummate ease and no bite whatsoever. Huge 3D soundstage type of presentation. Obviously seriously coloured.
I posted a video on YouTube of the Atma-Sphere set up a while back. Might post it later.
Similar threads
