Thanks for the kind response Mr. Pass and others.
I hope you are all staying safe and isolated.
I see that there are folks in Japan still selling Tokin 2SK180 and 182 VFETs for about $100 each. Now sure how well these work. It looks like there is much input capacitance.
I think I saw a single ended Aleph circuit using the 2SK180 somewhere.
This may be a better way to go.
Are the death diodes gate protection zeners?
I hope you are all staying safe and isolated.
I see that there are folks in Japan still selling Tokin 2SK180 and 182 VFETs for about $100 each. Now sure how well these work. It looks like there is much input capacitance.
I think I saw a single ended Aleph circuit using the 2SK180 somewhere.
This may be a better way to go.
Are the death diodes gate protection zeners?
The 2SK77B's I have are comparable capacitance. They all need a fairly
low source impedance. Operated common drain, the bandwidth of the
2SK182 appears wider than the 2SK77B.
Thanks again for your kind response.
I've been a big fan since my GFA555.
I confess I'm quite timid about ordering expensive parts from overseas.
I just ordered a matched quad of 2SK180s.
I found a circuit from Soundhappy with parallel 2SK180s fed by a single IXTN46N50L Mosfet current source. This appears to be a variation of your 2SK77B mu-follower.
Should I wait for a bulletproof circuit that even I can't make oscillate?
I've been a big fan since my GFA555.
I confess I'm quite timid about ordering expensive parts from overseas.
I just ordered a matched quad of 2SK180s.
I found a circuit from Soundhappy with parallel 2SK180s fed by a single IXTN46N50L Mosfet current source. This appears to be a variation of your 2SK77B mu-follower.
Should I wait for a bulletproof circuit that even I can't make oscillate?
They must be rugged, my Yamaha looks like its been through a crusade. I've heard that guitarists have used them for music amplifiers.
Most of the Fets I've gotten on Ebay have lead very short lives. I hope these break that sad tradition.
Do you cut your own insulators out of blank material?
I almost got THS-51 units because the terminals poke out of the top of the case. It looks like very little work to make an insulator for them.
I have a friend with some junked lasers. The entire top is a 4'x6" heatsink 3 foot long. Hopefully those will have enough acreage for the 2SK180s.
Thanks again for the help.
Most of the Fets I've gotten on Ebay have lead very short lives. I hope these break that sad tradition.
Do you cut your own insulators out of blank material?
I almost got THS-51 units because the terminals poke out of the top of the case. It looks like very little work to make an insulator for them.
I have a friend with some junked lasers. The entire top is a 4'x6" heatsink 3 foot long. Hopefully those will have enough acreage for the 2SK180s.
Thanks again for the help.
Sorry for that response.
I totally misread what you were saying there.
I thought the output device drains were usually tied to the supply rails.
In Yamaha news, I replaced the bizarre speaker connectors on the back of the B2 with some for-real binding posts that will accept 10-12 ga. wire as well as banana plugs.
A Swiss company called Speaker-Terminals.com makes beautiful gold plated machined speaker jacks for a wide range of vintage Japanese receivers and amplifiers. The jacks are mounted on black anodized aluminum blocks that mount using the original mounting holes on the amplifier. Everything fit into the original space with a minimum of fuss.
I totally misread what you were saying there.
I thought the output device drains were usually tied to the supply rails.
In Yamaha news, I replaced the bizarre speaker connectors on the back of the B2 with some for-real binding posts that will accept 10-12 ga. wire as well as banana plugs.
A Swiss company called Speaker-Terminals.com makes beautiful gold plated machined speaker jacks for a wide range of vintage Japanese receivers and amplifiers. The jacks are mounted on black anodized aluminum blocks that mount using the original mounting holes on the amplifier. Everything fit into the original space with a minimum of fuss.
I hate acronyms, I was looking up if the parasound hca design was related to the Yamaha design and stumbled upon a book called Audio Power Amplifier Design I am sure this has been discussed many times but this sites search feature and my patience are of similar quality. I did remember this thread...
If my summations and the information in this book are correct, you are a very humble man Nelson Pass. Have a look at the non-switching amplifier section, I could be reading to much into this.
If my summations and the information in this book are correct, you are a very humble man Nelson Pass. Have a look at the non-switching amplifier section, I could be reading to much into this.
The Yamaha amp I brought up is more exotic and unique than 99.99% of any amp old or new. Starting from silicone devices made specifically for it (multiple types) and not used in any other amplifier, all the way to its circuit design.
The cost new back then was similar to that of a small car. If it were made today and the front plate would be 1in thick aluminum and not called Yamaha, (inflation adjustment aside) it would probably have the cost a luxury sedan.
You should listen to one....
your B-2 needs new bulk caps. I went through 40-50 original caps to find 4 that were still close enough to the original specs. After 40+ years, that is not a surprise.
Use quality audio caps as replacements otherwise the lows will sound boomi ..like dong.
I would also be interested in a front section alternative...
Experimenting with daughter cards such as those made by @Mark Johnson
A friend of my have the B1, B2 and C1 and tried them in his system. He did not use them in original states but have it fully restored.
quote from him : in their orginal states : the best solid states devices with the worst passive components. That's explain why they do not have the reputation they deserve. Need to be fully overhauled to unveal their potentials. But once you did that the PP VFET offer performance on par with the best PP tube amps. He prefer the B2 to the B1.
If you want to use them, pay them a full restauration.
quote from him : in their orginal states : the best solid states devices with the worst passive components. That's explain why they do not have the reputation they deserve. Need to be fully overhauled to unveal their potentials. But once you did that the PP VFET offer performance on par with the best PP tube amps. He prefer the B2 to the B1.
If you want to use them, pay them a full restauration.
My 40 year old, unmodified B2 sounds superb. I can imagine what a modernizing overhaul would do.
I will be selling it, however, because I am now swamped with various Nelson Pass creations and will be attempting to build the new Sony VFET single ended 10 watt model when the feeding frenzy is over and the store offers it (since I have a collection of Sony VFETs already).
This B2 would be a good starting point for a renovator since the VFETs are still in good operating condition and sound great in spite of age.
I will be selling it, however, because I am now swamped with various Nelson Pass creations and will be attempting to build the new Sony VFET single ended 10 watt model when the feeding frenzy is over and the store offers it (since I have a collection of Sony VFETs already).
This B2 would be a good starting point for a renovator since the VFETs are still in good operating condition and sound great in spite of age.
I'd be curious to hear what does @Nelson Pass think about the harmonic profile of the Yamaha B-1
Pete
Pete