Allnic OTL/OCL Phono vs Allnic DHT

Here are some additional resources that may be useful-

From the Allnic H-10,000 OTL/OCL manual:

“Some circuit experts might be concerned about DC potential in the music signal in an OTL/OCL design.  However, the chance of this problem occurring can be essentially and reliably 100% mitigated. To do this, Allnic uses a “floating power supply circuit”, a design that deals with the issue by not creating any DC potential in the first place, or such a small potential that it is harmless.”

My personal experience with these units:  the H-10,000 requires less user attention for tube maintenance, more stable circuit and more robust to different environments.  

For the more advanced Allnic circuits I recommend this read:

https://www.kevalinaudio.com/circuit-balance-review-recommendations

For Manuals:

https://www.kevalinaudio.com/copy-of-current-legacy-allnic-manuals

For Reviews:

https://www.kevalinaudio.com/allnicreviewcurrentlist

Ralph, As phono stages go, OCL is more unusual than OTL, of course. I thought that was salient to my point. As the owner of an MP1, I know about the OCL/OTL linestage section, but the built in phono is capacitor coupled to the linestage, at least in my unit.

$48K is a bargain compared to the SS  Vitus MP-P201@64K

AND you get the tube magic that SS SOTA cant replicate.  

https://jaguaraudio.com/product/mp-p201-mk-iii-phono-preamplifier-by-vitus-audio/

Might as well drop another couple grand for vintage Euro glass for the Allnic too, just cuz.

never heard the sound of OTL phono amps. 

@joeycastillo nearly all phono sections are OTL; OTL stands for 'Output TransformerLess'.

Since we have been making preamps with direct-coupled outputs (so OCL and OTL) for decades now, we had considered doing a phono stage as a stand-alone but kept running into the issue of doing the direct coupled output.

That requires an additional tube and a servo circuit. We patented a method of doing this balanced; when its done single-ended you usually have to have some kind of timer or protection circuit to be active until the output has warmed up and stabilized properly. David Berning made a very interesting preamp using this technique about 40 year ago called the TF-10. 

The tricky bit is making sure the servo does not affect the sound of the unit, for example if the opamp for the servo gets changed out for another. The design should be immune to that sort of thing.  

You can't have heard it before, because to my fairly extensive knowledge, this is the first such product (OTL/OCL phono stage).  However, OTL tube amplifiers have been around since the 1950s (Futterman) and have always been a minority species, my favorite for driving any high impedance speaker but particularly for ESLs.  In fact, I have been using OTL tube amps to drive ESLs since the mid1970s.  Tube OTL headphone amplifiers are also not new; the first one I heard was designed and marketed by Futterman in the 60s. This is easier to do because the typical headphone has a very high input impedance compared to any speaker.

It's a bit ironic to have a phono stage that uses SUTs to step up gain and then sports an OTL/OCL output as a major asset. But I like Allnic too.

I am interested too. never heard the sound of OTL phono amps. 

I've always wanted to try Allnic products based purely on aesthetics.   

If they sound nearly as good as they look... JACKPOT!! 

The idea of an OTL/OCL phono stage intrigued me, so I looked up this Allnic product.  At $45,000 retail, you are not apt to find too many, except dealers, who have compared it to their DHT phono stage, which also costs well into the 5-figure range.  Anyway, to do away with both a transformer and capacitor for coupling, the unit must use some sort of servo mechanism to cancel DC offset at its output.  This has been done before, a few times, with OTL tube amplifiers. The servo itself then can become an issue, either for coloring the sound or for developing faults in its operation.  However, I have faith that Mr Park can get around such problems.

No transformer ought to be better than even a very good transformer or a very good capacitor, so your observations don’t surprise me. I’d like to find out more about the OTL unit.