Just pushed the button on a B-2

stoutblock

"If it sounds good, it is good." Duke Ellington
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A local B-2 popped up on that auction site this morning with a very decent BIN so I pushed the button. Not sure yet if it is a fellow AK'er? Description seemed honest with several serious operating issues listed on the amp but no technical analysis. I guess he has owned it since 1990, has been in storage for several years and never been touched by anyone since he has owned it.

I know, it is a big risk, but you guys always talk about what a superb sounding amp this is and local pickup reduces the price quite a bit.

I am digesting information for the site

http://www.audiokarma.org/forums/showthread.php?t=439559
http://www.audiokarma.org/forums/showthread.php?t=234384are
http://www.audiokarma.org/forums/showthread.php?t=355245
http://www.audiokarma.org/forums/showthread.php?t=307226
http://www.audiokarma.org/forums/showthread.php?t=208759&page=2
http://www.audiokarma.org/forums/showthread.php?t=69809
http://audiokarma.org/forums/showthread.php?t=45419

there any more postings?
 
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Having never heard one, I looked at that one closely last night. Very interesting piece of gear. I thought the issues sounded like a fairly reasonable set to deal with. Good luck with it and hope to hear how much you're enjoying it soon.
 
Just drove 200 miles round trip to pick it up. Pretty cool old guy who owned it. He had a dozen electric guitars and a couple of Marshal amps and I guess he use to be in a band down in SF in his younger days.

Good news is I think I have a good one! I was expecting it not to work but he said it works fine but only on #2 input. #1 input has a broken RCA terminal.

Sure enough, he had it connected to a couple of speaker lab 7s and it sings just fine. Meter and lights too!

The volume knobs have no effect on speakers A, but the volume is full on? The switches are a little sticky but seem to work.

Once home, I was able to look it over closer and the outside only has a few small nicks. I looked inside and its quite clean. A little dust and some cat hair but not bad at all. No hot spots on the PCB and no leaking caps. Transistors are 2SK76A and 2SJ26A.

He bought it from the original owner back in 1990. He also gave me a great buy on a match C-2 that he bought from the same guy.

Anyone know where to find a service manual for the B-2?



IMG_6152yamahaB-2net.jpg


IMG_6149yamahaB-2net2.jpg


IMG_6153YamahaB-2modnet.jpg
 
Thanks Dave!

Well, this is too easy. Checked voltage, right on. Checked Bias and DC offset and they needed a little tweaking but settled in fine. I've had it on now for about an hour and seems to be fine.

Checked DC at the speaker terminals and A speakers are fine but B speakers are at about 60mv. Hmmm, that is strange. The driver board is at about 4mv.

Might be the switch or attenuator?

Should be fine now to hook up to some speakers and then I will try cleaning the switches and attenuators.

The input 1 RCA terminal appears to be an easy fix.

It looks like some of the caps are glued in. I thought these early amps did not have the glue problem?

Oh well, all the caps will get replaced in short order.
 
damn, should have pulled the trigger this morning!!!!

the older pale orange glue (late 70s, early 80s) seems to be OK still in every amp i've come across. it's the stuff they started using in the M-XX line that has been a real problem, it seems from reading threads. i just finished with your M-4 and the glue hasn't affect the PCB's at all. Brutal has probably been keeping the closest tabs on this issue and he may have something to add to that, though.
 
damn, should have pulled the trigger this morning!!!!

Sorry about that Chris (not)! I bought it around noon PST after I confirmed he would let me pick it up. It would have been another c note to have it shipped the 100 miles to my house (plus the risk of damage).

Always wanted to hear a healthy B-2. It should sound great with the C-2x!

Man these speaker terminals are not what this amp needs! They are way better than the spring clip POS from some amps of this era but not up to the task of connecting to modern cables.
 
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Hey stoutblock, congrats! Nice amp and have fun. Looks great with those big meters.
Happy listening:music:
John
 
Congrats, looks like it will clean up nicely. Hope its fully operational.

For a minute, from the title I thought you were dropping smart bombs or something...
 
Hey stoutblock, congrats! Nice amp and have fun. Looks great with those big meters.
Happy listening:music:
John

Yes this is fun and what fine meters they are to watch.

Congrats, looks like it will clean up nicely. Hope its fully operational.

For a minute, from the title I thought you were dropping smart bombs or something...

Just noticed that, LOL! Peace brother...

Spent several hours doing a deep clean, and replacing the RCA terminals with some quality ones from connexion. To do it right is a little harder than it looks but well worth it in my book. Once all the controls were cleaned the DC was less than 7mv on all outputs.

IMG_6157B-2net.jpg


Once I was sure it was healthy, I hooked it up to my Soliloquy 6.5s and to the C-2x. Then I spent several hours enjoying this amp. What a wonderful sounding amp! Everything works just fine.

IMG_6162M-2net.jpg


I'm thinking about upgrading the speaker terminals, add an IEC power connection (wimpy power cords just bug me!), and then do a complete cap R&R. Right now, I think I will just enjoy the music!
 
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Congrats on the very sweet B-2 deal! You don't see those come up that often anymore and especially at that price. Looks like it's gone to someone that'll give it the attention it deserves too. :thmbsp:

Hope you enjoy it as much as I do mine and I for one would be interested in hearing your comments on how it compares to the M-2. :D
 
Congrats on the very sweet B-2 deal! You don't see those come up that often anymore and especially at that price. Looks like it's gone to someone that'll give it the attention it deserves too. :thmbsp:

Hope you enjoy it as much as I do mine and I for one would be interested in hearing your comments on how it compares to the M-2. :D

I need to spend more time with it, but right off I can tell you it sounds like no amp I have heard in my system before. The Soliloquy's are quite revealing and easily expose signature of anything connected to them. They are about 92db sensitivity so I don't think they miss the extra punch of the M-2 but the wife was sleeping last night so did not really test it (tonight!).

I did listen to Blind Faith (FLAC > Audio-gd Ref 5.2 > C-2x) which is not the best recording IMHO but through the C-2x/B-2 combo it seemed very detailed with deeper and wider sound space. I need to listen to it again with the M-2 but I don't think I have heard this album sound this good before. I don't think I have heard the instrument placing on this album before last night.

I was expecting it to be more "tube like" but although it has some warm tone, HF and LF seem extended, and the bass has more punch than most tube amps I play with. Although it does not sound overly bright, some of the HF notes coming out of the tweeter can almost be startling. Musical but startling. The mid range seems totally neutral (not forward or aft of the HF/LF). Overall it sounds well balanced and very musical. It does not sound artificial yet it seems to make even poor tracks sound really good.

I have some Bill Evans 24/192 tracks and the piano tone is very impressive. Not what I remember with my Primaluna tube amps but then I did not have the C-2x then. Tonight I'm going to listen to some Jim Hall and Wes Montgomery for Jazz guitar tone.

So far I have found the listening sessions to be even more entertaining than the M-2 and I have a very high regard for the M-2.
 
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Tonight I'm going to listen to some Jim Hall and Wes Montgomery for Jazz guitar tone.

So far I have found the listening sessions to be even more entertaining than the M-2 and I have a very high regard for the M-2.

I'm thinking the B-2 will continue to impress since it does jazz very well.

Enjoy!
 
I'm thinking the B-2 will continue to impress since it does jazz very well.

Enjoy!

Yes, that it does!

My listening room likes a little compensation to sound right and the M-2 sounded best with the bass tone control up a couple of clicks on the C-2x. Even though the B-2 has less power, it actually likes the C-2x set flat (tone bypass) to sound right. At the M-2 setting, the bass sounds a little muddy with the B-2.

However, listening to hard rock the M-2 can really make the Soliloquy's pound out some solid and loud bass. The B-2 has impressive bass ability but struggles just a little with these speakers when really high db bass is expected. Not bad, but the M-2 does this quite well.

My M-2 is very healthy with all new caps with upgraded IEC, power chord, and better RCA/speaker terminals. I think the B-2 also needs to be at the same health level before I can fairly judge this M-2 B-2 comparison.

As is, the B-2 clearly has some acoustic quality that I am quickly getting very fond of!
 
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As is, the B-2 clearly has some acoustic quality that I am quickly getting very fond of!

Thanks for the comparison! I've never heard an M-2 but I've always wanted to ever since I heard how nice the M-4 sounds. The M-2 looks like a very fine piece of work and IMHO those Toshiba outputs are some of the best BJT's ever made for audio use. Having said that what I'm getting from your comparison is as I suspected; the M-2 will win out as far as brute force total SPL is concerned but when it come to the overall sonics, the B-2 has it going on and since my heavy on the bass head banging days are pretty much behind me now and my listening space is somewhat small, I'm thinking I won't be trading my B-2 for an M-2 any time soon. :no: :D

Also, if it were mine, I would add replacing the protection relays to your B-2 reconditioning list. :thmbsp:
 
Congrats stoutblock,
that is the very same (pre/power) combo I am running into KEF Concertos.
I am VERY happy with them,
I don't imagine you will ever want to look for another amp.
Cheers, Timo.
 
Congrats and welcome to the wonderful sound of vfet power.

While I'm sure you are jacked about the amp, I'm gonna say that the real steal was finding a C-2x for a nice price. It's a fantastic preamp with the best on-board phono stage I've ever heard.

Now that you've done the RCA jacks, look into 5 way binding posts for the speaker terminals....

Hang on to both forever.....
 
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