Interesting 'LP Audio' 20w single ended Class A amp from Valab
I referenced this in a wanted thread recently but it's since arrived and it deserves its own space I think.
Quite a few people here have dealt with Kevin at Valab over the years, most of them latterly I think as a source of quality parts and DIY components, but he's come up with some pretty good kit over the years, I'm not sure the extent to which he is directly involved in manufacture but I do believe he is engaged in design, and many of the internal parts are quality bits sourced within his native Taiwan rather than the Chinese mainland.
I've had a few bits over the years probably going back more than 10 years to an early non-oversampling DAC that was quite popular among forum-goers, a later USB version, and most recently a directly heated triode preamp which I had quite a bit of fun with and reviewed here as well.
So an attempt to satisfy a curiosity about Pass Aleph-derived single ended power amps out there led me to this LP Audio Spirit 0-L1 - https://www.ebay.co.uk/itm/LP-Audio-.../222735396465? (no listings current at the moment but I'm sure it will be listed again). I've had to wait a few weeks for it, first of all because Kevin removed the 220v mains transformers and went to his supplier (in Taiwan thankfully) to get some 240v ones made - he's just been through the same procedure for another regular customer in Australia. (It then got held up for 2 weeks in UK customs over the holiday but that's another tale). Kevin had done this previously for me for the DHT preamp and Valvebloke at the time when I got him to check it over confirmed 240v operation and remarked on how well it had been done (not with a different mains transformer - this was till 220v, but with other circuity which I didn't quite follow but which I was assured was effective).
Something I didn't give much thought to was the IPR of this, it seems to be based around the principles of the Pass Aleph-Mini, a cut down single gain device version of the Pass Aleph J circuit that's popular on DIY audio. But it doesn't use any of the 'approved' DIY boards (which it shouldn't have anyway as this is a commercial venture) and I'm not sure if it will have paid any royalty to Nelson Pass. Anyway it's not Pass branded in any way so perhaps it flies under the wire as 'inspired by' - it can hardly be said to be a novel concept these days, and the execution is everything.
On the topic of execution, it seems to be very well constructed, and is extremely heavy for the size of it. It was well packed and arrived in spotless condition. On first impression the thing you see are the fins that cover it - which turn out to be necessary as it gets very hot indeed. It seems to be made up entirely of mains transformers (two of them, for double mono), fins, and those gain devices. It has lights inside which are a bit cheesey but at least you won't forget to turn it off.
The sound? Well out of the box I wasn't sure, I plugged it into my study system (for where it's destined) and it immediately underwhelmed. A bit harsh was the judgment, though there seemed to be plenty of bass, plenty of output, and plenty of detail. Hmmm. I thought I'd pull the Pass DCB1 buffer preamp (no gain) out of the setup and try again - and immediately it improved a lot. This is actually the first time the Pass had failed me. I believe the 20w amp has a 20kohm pot on the front of it (not sure why) but I suspect this is not ideal. Anyway putting either my Trichord Research Genesis III transport/player or the Schiit Modi Multibit DAC directly into it vastly improved the sound.
As it warmed up and played in it made a super job of driving my little Tannoy DC6 speakers in the study (couldn't try with vinyl as my Garrard 401 is doing duty in the main system while my TD124 plinth is being modified back at Russ Collinson). Great bass, lovely bloom in presentation - proper single ended glow, but apparently no down side in woolly bass, indeed bass comparable to the 200w Class D amp I've been using in there - which BTW works beautifully with the Pass, as indeed a Leak Stereo 20 did before it, both of them being high sensitivity power amps. I would say the little LP Audio isn't nearly so sensitive - indeed I would say unless you are driving with a single source, a pre with gain is a pre-requisite. (I have a valve one coming from Alan/Firebottle so I suspect that will be a nice combination - stay tuned).
In the main system, driven by the 14db gain EAR 912, the LP Audio upped its game again. I wouldn't say it matched the STA25 in smoothness or authority, but it did that lovely single ended thing of being very up front/3D, layered and atmospheric, while making a decent fist of the bass, better than I expected (the 12in HPDs being tough to manage in the bass frequencies) - I think due to what I read from research on the Aleph Mini, if such is what it is, a damping factor of 150, far better than any single ended valve amp out there. It's an exiting listen though I wouldn't swap it out for the Radford on Tannoys. On easier to drive speakers, I'd be prepared to bet it would come into its own in delicious fashion.
Anyway, pretty pleased with this, will report more as time progresses.
https://i.imgur.com/HM7Sqo2.jpg
