This may not be terribly helpful as I don't own one of their amps but I'm a more than pleased owner of the YDA-1 DAC a gorgeous and fantastic sounding piece of equipment. Regarding the amps sorry to hear that your inquiries were not answered but a few thoughts.
Of the 2 amps you mentioned the A-08S puts out 2 watts and the A-011 4 watts so regardless of what the intended impedance is you're pretty limited to high impedance high sensitivity speakers from the get go. The writeup for the specifically mentions Altecs and Lowthers.
I found an image of the manual for building the A-08S kit here:
That shows the schematic for the amp. All in all it's such a simple design I can't imagine needing much in the way of post sales service. Either way I hope it works out for you and eager to hear what you think of a Yammie amp if you do end up picking one up.
I owned the A-08s for about one year and paired it with 102db ZuAudio Definitions. At that time there was a US distributor (I forget the name), but the amplifier never needed service. Eventually and although I enjoyed it a lot, I decided that I wanted a bit more power. Srajan (6Moons) also owned an A-08s and wrote about it extensively I have always found Srajan responsive, and he might be a good place to start.
The 6moons review is here very extensive with great pics:
And the link I sent you earlier was from the German importers website which is quite good. The previous US importer was I believe Venus Hifi and I think they are now out of business.
And the 6moons link I gave you starts on the second page sorry here it is from the beginning.
The Current Yamamoto North American distrubitor is Ocellia Audio in Montreal Canada.
I'm intrigued by the lack of owners and threads about this brand. I was aware of Srajan's reviews and those also fueled my interest. The few things I came around sound appealing, but the fact they are so few are also making me pause.
Charles1dad, thanks for the name! I knew there was another rep back in 2005 when Srajan wrote his articles and knew they were out of biz, but didn't know there was a new one. I will get in touch.
I was hoping to be able to discuss with the manufacturer because my intended use is a bit different from mainstream (mainstream in the context of a niche like flea-powered SETs, that is). Will see what Ocellia has to say. Still, I can speak with Elina at Lamm, for example, when I have a question...I was hoping a similar situation when dealing with another niche manufacturer. Oh well.
FWIW, I'm building my own 4-way active speakers, and plan to use a pair of Yamamotos to drive the tweeters and midranges directly. Tweeters are 102dB/W and 5ohm flat impedance. The midranges are TBD, but a couple 100dB/W options and some are 8ohm and could do one at 16ohm. With only one pair of speaker outputs in the Yamamotos I'm not sure what impedance they are expected to be connected to. Hopefully the North American distributor will know.
I do not think the owner/designer of Yamamoto Japan speaks or writes much English ... that said the company SHOULD forward messages to a distributor or have someone at the main office who does speak English.
I had owned an A08s for a period but it really did not have enough power for my speakers at the time. BEAUTIFUL build and sound within its limits though. Would not be a difficult amp to repair by any competent repair shop specializing in tube gear ... simple and straightforward layout on all parts
One other suggestion. . . not specifically about the Yamamoto, but about your design plans in general. . . You could contact DejaVu Audio outside of Washington, DC. They make their own line of 45 and 2a3 SET amplifiers and are highly knowledgeable and willing to customize.
I would second the Deja Vu rec from Gsm18439, I live near Deja Vu and have an amp and preamp of theirs, sound quality and customer service are both tremendous. In addition to building great amps they build custom crossovers as well, which it sounds like you may need.
Thanks all for the input.
I contacted Ocellia and they are being responsive, which is great.
Jrinkerptdnet and Gsm18439 owned an A-08S but decided they neeeded more power. I realize power is THE challenge for the 45 tube, which is likely most noticeable in the bass.
How did you like the trebble and midrange the A-08S provided, compared to other SETs?
I was on DejaVu's website but didn't see a link to their own amps. Does anyone have a link?
Jond, since you have one of their amps and own the YDA-1...ever compared Yamamoto amps to DejaVu's?
Lewinskih01 I've never heard a Yamamoto amp sorry but I've heard many of Vu's amps, if you're looking for the 45 tube with more power I know that he makes a pushpull 45 amp, I had one on loaner a few months ago it was pretty amazing perhaps the most detail and transparency I've heard in my system. Their website does leave a lot to be desired sadly but give them a call (703) 734-9391 or email them firstname.lastname@example.org I'm sure they will give you any into that you need. And the combo of YDA-1 and Deja Vu amps to me is pretty spectacular at least in my system. Cheers!
Where does it indicate that DejaVU builds gear? Maybe I missed it on the site but see gear they sell from other companies? Thanks
Apparently they do not advertise their own gear on their site although I vaguely remember that they used to years back. I've been to the shop a couple times and they collect all kinds of vintage parts that they use in their gear builds. Assuming they still build gear, you will have to contact them to see what they have in rotation or if you want custom work done.
As others have noted, the DejaVu website leaves a lot to be desired. It does not come close to describing the range of gear that they have available - including their own equipment. Visit the shop or send an email or call them. Despite the absence of their own equipment on their website, they make a range of electronics including a full range of amplifier topologies - SET, PSET, and PP using 45, 2a3, 300b, et al - using vintage components. I had both a Yamamoto A-08s and a DejaVu 45/2a3 SET and liked them both. Simple circuitry. Very similar sounding.
They absolutely build their own gear take a look at my system here if you care to see their handiwork, and as I advised the OP just give them a call or drop them an email.
So this just popped up in the classifieds:
I have no affiliation with the seller but for $1600 that is a steal for a Deja Vu 45 amp, if you are still looking Lewinskih01.
Definitely a steal. There is also an ad for a pair of PP 45/2a3 monoblocks. Unlike Yamamoto gear, cosmetics are very utilitarian.
I own a very sweet sounding De Java pre amp and I know there amps a also great.
Thanks for the heads-up guys. It does look utilitarian indeed.
I just saw this thread. I have the A-011, from Brian at Venus Hi Fi. I've contacted Yamamoto directly several times. They have always been very responsive. I use this with Shindo preamp and Devore O/93. I think it's a nice combo. I'm planning to try a Shindo Cortese to see what type of improvement I get from a more expensive amp. I thought it comes 8 ohm standard, but their is a 16 ohm version...not sure