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Yamaha B-1 Quickie

rottalpha said:
I will find out one of these days.


The B-2 sound so close to B-1, I wonder how I would ever hear something in-between


I you saw, it is not impossible, but it is very difficult due to size limitations. I strongly suggest you exhaust every possible option of obtaining a kit from Clinic or a boards from Vint Age, first, before you go to the full DIY route.


I was feeling guilty to keep hijacking your thread :D
Click to expand...
All good. Either way is helping :-)
Got the kit from clinic and set to start the work any day now.

I had 3 B-1's and unfortunately had to let go of 2. But I am set to restore this last one properly.

You are right about the B-2 and B-1. They do sound very close, it is only on most demanding pieces of music with a lot of information the B-2 starts to get a little --mushy--
and starts to loose definition.
 
vintagejapan said:
All good. Either way is helping :)
Got the kit from clinic and set to start the work any day now.

I had 3 B-1's and unfortunately had to let go of 2. But I am set to restore this last one properly.

You are right about the B-2 and B-1. They do sound very close, it is only on most demanding pieces of music with a lot of information the B-2 starts to get a little --mushy--
and starts to loose definition.
Click to expand...
I gess the beauty is in the ears of the beholder :)
To my tired ears, the B-2 never sounded mushy. I would call it more musical, but not mushy :)
BTW, I am assuming you compared restored unit, correct?

going through a few right now...
Here is some B-2 porn:
IMG_20180102_002655054_HDR.jpg

IMG_20170916_164445002.jpg

IMG_20170927_203446363.jpg
IMG_20170917_085324487.jpg
IMG_20170917_223807184.jpg

IMG_20171016_202154871.jpg
 
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rottalpha said:
I gess the beauty is in the ears of the beholder :)
To my tired ears, the B-2 never sounded mushy. I would call it more musical, but not mushy :)
BTW, I am assuming you compared restored unit, correct?

going through a few right now...
Here is some B-2 porn:
View attachment 1081634
View attachment 1081635
View attachment 1081644

View attachment 1081638
View attachment 1081641
View attachment 1081643

View attachment 1081639
Click to expand...
rottalpha said:
I gess the beauty is in the ears of the beholder :)
To my tired ears, the B-2 never sounded mushy. I would call it more musical, but not mushy :)
BTW, I am assuming you compared restored unit, correct?

going through a few right now...
Here is some B-2 porn:
View attachment 1081634
View attachment 1081635
View attachment 1081644

View attachment 1081638
View attachment 1081641
View attachment 1081643

View attachment 1081639
Click to expand...
Wow,

Yes, went through a few B-2's with a complete restoration. Maybe not as deep as resistors, but everything else done.
I have the NS-2000 which are a very good match for the B-1, on moderate volumes the B-2 is a ok, when you do put a little more demand on the power supply that is when things start to get a little out of hands..

This is from my listening sessions. My preamps are Luxman, solid state and tube.
I think there is a very nice synergy of the tube pre combo with the V-fet Yamaha's
 
vintagejapan said:
Yes, went through a few B-2's with a complete restoration. Maybe not as deep as resistors, but everything else done.
Click to expand...
I meant to say..it is not just the 1% low ppm metal film resistors that will hold those voltages strapped to where they are supposed to be when the upside down mounted PSU board acts as an oven lid ..that PSU is beefed up in all the right places...with subtil enhancement...Hint: none of those semis are the ill-fated originals and one would need to look a bit more through those black heatsinks or underneath the bank of power resistors :p
PSUs get tired because of heat...especially those full of carbon film resistors and semis operating at their spec limits.

IMG_20171013_101402218.jpg
 
I also need to mention is that most of my knowledge and work progress on these amps, I owe to a few, much smarter people on this forum.
There is a master restorer floating around this forum. He might one day decide to do a presentation of a full and proper rebuilt...miles above anything I do.
 
rottalpha said:
I meant to say..it is not just the 1% low ppm metal film resistors that will hold those voltages strapped to where they are supposed to be when the upside down mounted PSU board acts as an oven lid ..that PSU is beefed up in all the right places...with subtil enhancement...Hint: none of those semis are the ill-fated originals and one would need to look a bit more through those black heatsinks or underneath the bank of power resistors :p
PSUs get tired because of heat...especially those full of carbon film resistors and semis operating at their spec limits.

View attachment 1081666
Click to expand...
Agreed,

I have followed a few very valuable suggestions on this forum when started to restore this type of gear.


Here is one of the B-2's psu and driver board I did.

I admit the B-2 was my first love of the Yamaha V-fet sound. The sheer speed and transparency is very hard to find elsewhere.
 

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vintagejapan said:
Noticed you didn't replaced the Sanken switching transistors.
Click to expand...
No, I did not think I needed to
TR1, TR2 are 400v devices acting as voltage stabilizers for ~200v
TR3, 4, 5 and 6 are 120v devices acting as B-, B+ switches. They see ~93-96V (according to schematic)

The protection circuit works flawlessly. If these things would fail, they would fail because of other components and I believe I have addressed those already.
 
rottalpha said:
No, I did not think I needed to
TR1, TR2 are 400v devices acting as voltage stabilizers for ~200v
TR3, 4, 5 and 6 are 120v devices acting as B-, B+ switches. They see ~93-96V (according to schematic)

The protection circuit works flawlessly. If these things would fail, they would fail because of other components and I believe I have addressed those already.
Click to expand...
I think I will replace them just for piece of mind.

Here is the B-1, I will strip everything.
 

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