Yamaha B-1 owner roll-call (and info repository)

cdfac

AK Subscriber
Subscriber
I'm curious how many other guys out there own B-1's, what work you've had done to it (in particular if you have had some problems), whether or not it's your main amp, and anything else about your experience you'd like to share.

I'll start, short story long ;). I purchased my B-1 and UC-1 a few years ago from AKer Mark B, who has one of the best Yamaha collections around. At first, I didn't love the sound as much as I hoped I would. I thought it was a bit dry and dark/rolled off. The first minor improvement came when I replaced the original speaker relays, one or more of which was causing me some problems. That seemed to give the sound a bit more "life." Still, there were times when I preferred the sound of an M-4 in my setup.

Not too long afterward, I sent it off to Avionic for a recap and tune-up. This definitely made a sonic difference for the better, not to mention being mandatory from a reliability standpoint. The B-1 runs hot when dialed in, and you have to watch the capacitors which are near power resistors, particularly in the 250V supply section -- if one of those goes, your VFETs will likely go as well. I can tell you that the 10uF/250V capacitor at the top of that PCB gets almost too hot to touch, even after re-positioning the resistors that are helping to heat it up, so 105C ratings are a good idea in as many places as you can put them. But even then it seems that these amps are quite reliable, and I think I'm quoting this from somewhere, the most dangerous thing to a B-1 is probably the tech [or wannabe tech, like me!] working on it -- VFETs are safe to mess with only after all of the bigger caps have been completely discharged, as per the service manual. I'm luck to live near Avionic, who did a great job on mine, and I think that was his first VFET amp. I didn't mind being somewhat of a guinea pig, but if you take yours to a tech who has no VFET experience and whose work you are not familiar with, just be careful! Even EchoWars has expressed reluctance in working on B-1's, if I am allowed to loosely quote him on that.

At this point, I was enjoying the amp on various sets of big Infinities -- it wasn't as transparent as some other amps I'd had, including some of the later Yamahas, but it could fatten up the sound in a [good] way that my other amps could not. Still, I was in a continual debate with myself as to whether the amp sounded good enough to justify keeping, considering how much they can sell for.

Having gained some confidence with various recap and building projects, I decided to tackle my last real concern about the amp: the main filter caps, for which there are no drop-in replacements available. Now, I had no real reason to suspect that mine weren't still performing well, but my previous positive experiences with filter cap replacement pushed me convinced me that it was worth trying here. And at some point, this will be a concern with all B-1s. It wasn't an easy or fun project, and there are some things I'd do differently the next time around, but I'm currently enjoying the fruits of my labor and I think I made the right call. Several items in my system have changed since I had last run the amp before the new filter caps so all of the acclaim doesn't belong with the B-1, but as it stands right now I don't think I've ever heard my system sounding quite so complete, well-rounded, and downright musical. The B-1 is really capable of some incredible dynamics with the right speakers! The sound might still seem a bit rolled off to some listeners, but I think this is mostly due to the distortion characteristics of the VFETs compared to BJTs. Still, I can't deny that the B-1 doesn't have as much "air" as some newer high-end offerings -- for me, its magic lies more in the lower treble on downward.
 
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Hi cdfac.....just to chime in.....just recently replaced the main capacitors on my Yamaha M-40 power amp <part of a complete recap>. Since I could not find caps of the same rating (22000uf 69v), I ordered up some Nichicon Gold Tune 22000uf 80v from Michael Percy online. They are a bit wider in diameter and a bit taller, cap legs spaced a tad wider and are situated the opposite way, but I managed to modify the existing cap bracket and also the circuit board to fit.

So, what did I get???? Lets say, welcome back honey! Sonics, clarity, just all over audio bliss.

If she can make it to 2017, we will celebrate her 30th birthday, heheh.
 
I'm curious how many other guys out there own B-1's, what work you've had done to it (in particular if you have had some problems), whether or not it's your main amp, and anything else about your experience you'd like to share.

I have 3 B-1's but no real information to share. One is at Avionic's for him to work his magic and the other two will follow as he gets a chance to finish them up. I don't want to operate them until Avionic recaps them and gives me the green light to turn on the power switch for fear of frying VFET's.
 
It appears that B-1 owners are a rare and select few and far between. Sadly, the closest I've been to a B-1 is the sales brochure and the service manual. :D

Too bad it's so dangerous and expensive to ship these amps around or we could start some kind of an exchange program so we could all have the pleasure of trying out different gear without having to own it outright. I'd be happy to loan out my B-2 for a month in order to try a B-1 for the same amount of time. :thmbsp:
 
It appears that B-1 owners are a rare and select few and far between. Sadly, the closest I've been to a B-1 is the sales brochure and the service manual. :D

Too bad it's so dangerous and expensive to ship these amps around or we could start some kind of an exchange program so we could all have the pleasure of trying out different gear without having to own it outright. I'd be happy to loan out my B-2 for a month in order to try a B-1 for the same amount of time. :thmbsp:

Um, well, I've uploaded (*sportsbil*) a Service Manual & Owner's Manual for the B-1 ...

Oh wait, I haven't uploaded the Service Manual yet. But the Owner's manual is a hell of a read.
 
Yup, isn't that cool? The owner's manual was a "scroe".

attachment.php
 
I have 3 B-1's but no real information to share. One is at Avionic's for him to work his magic and the other two will follow as he gets a chance to finish them up. I don't want to operate them until Avionic recaps them and gives me the green light to turn on the power switch for fear of frying VFET's.

I wonder what size bribe Avionic will need to ship that to me? :D
 
I wonder what size bribe Avionic will need to ship that to me? :D

He won' t require a bribe as long as you don't make him pack them up. Just drive over to his place to pick them up. It's not far from Colorado:D:D
 
I'll be in Chicago early next week, maybe if I re-route my return Wed...

But HTF does one get to Ft Dodge, IA via air from anywhere else? :D
 
I'll be in Chicago early next week, maybe if I re-route my return Wed...

But HTF does one get to Ft Dodge, IA via air from anywhere else? :D

Doesn't Avionic have one of those Eagles parked in his back yard. Maybe he can fly over and pick you up!:yes::D
 
I'm the owner of a project..........or parts B-1. Depending on the test results for the vfets.
It's blown the 5A fuse that feeds to the left side of the amp. It's in need of a recap, but there's no obvious damage anywhere in the amp.
 
I'm the owner of a project..........or parts B-1. Depending on the test results for the vfets.
It's blown the 5A fuse that feeds to the left side of the amp. It's in need of a recap, but there's no obvious damage anywhere in the amp.

Compliments of EW I think.
 

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TO-3 on steroids

B-1 FET compared to a regular TO-3 transistor.
 

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