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Hey speakerman57 ! After a month or two of listening stock and keeping my mitts off, I've come to the conclusion that the A08 is a hair dry and can be a bit harsh/hashy on treble transients. I had been eyeing the ASC film coupling caps for a couple weeks and finally gave in. The only PIO caps I had around at approx the right value were Jensens, so in went a pair of .33uf in place of the .22 stockers. My only once in a while reseervation disappeared. Transients are silky, but just as fast, the midrange is more mature, the whole enchilada more organic. ooooh baby. PLEASE NOTE: Screwing with parts tends to screw your warranty, so think twice. You've been warned. (Just thought I'd better say that before someone injures themselves or blows up their amp and wants Brian B to service the thing under warranty . . . . . ) I do believe I'll bring this little beauty along to RMAF to tickle the HiEff Audio Note E/LX Signatures, which is what it is doing in my living room. Hot doggies, better than ever.
What coupling caps where used in the stock amp?
Dave, Sorry to hear that your Yamamoto sounds dry. But of course I also tweak/voice my speakers to my liking. I am running JBL E130(frames) reconed with 2225 kits for a (approx) 99 db efficiency. I am using a 1.2 mh coil in series with the JBL bottom and running a Great Plains 902 on 650hz round wooden tractix Edgarhorn with oil/MPT/MPP (3 caps in parallel) for 14.5 ufd which is 1st order at around 1.3khz into a 8 ohm L-pad. Rounding out the bottom is a JBL 2242 18" sub with PE plate amp. I have the older A-08 Yamamoto with EML 45's (Great tubes) and I can only say if they are "dry" sounding, then that must be a sound voicing that works for me in my small listening area. Downstairs, I have Wellborne DRD 300B monoblocks/ASL wave preamp(single 12AU7) running 2 Pi Towers. I did a comparison between the 300B's and the Yamamoto 45 and found the 45 amp has more inner detail and a better soundstage and a deeper soundstage. If I never had the Yamamoto, I would say the 300B amps are great. Downfall for the 300B amps is EH 300B's and 6N1P vs the handpicked tubes for the Yamamoto which makes it a hands down winner. What speakers are you using on your Yamamoto? I have tried various speakers on mine and found the compatability factor is very critical for getting that "ultimate" sound that friends of mine have heard and puts them in a daze. They tell me that they have not heard such detail in such a little amp!!! Ron
The Yamamoto is an alternative to my Audio Note Conquest Silvers with a CDT2/II and DAC3.1x up front, followed by an M3 pre and AN E/LX Signatures batting clean-up. At 98dB with external crossovers (20+lbs of copper foil caps/channel, I can assure you they were not the source of the bit of edge. I finally decided that the ASC coupling caps might be the culprits and replaced them with Audio Note copper foils. Voila !! Smooooth, and some nice additional body as well. (Don't try this at home kids, unless you didn't want a warranty anyway!) I'm using the Emission Labs 45 meshplates. Yummy. Nice to see a meshplate that actually has MESH for a change, too.