Class A SS JLH/PLH

[TubeHiFiNut]

Just checking in on my progress.

Work has been all consuming this week so I have not had the time or opportunity to switch amps around.

We have my high school reunion on Friday night, Computers for Kids, our Lions Club Annual BBQ and my Bride's high school reunion on Saturday.

Still have to drive up North to pick the Quicksilver Monoblocks (now running KT90s, thank you Golden Gate ER ).

Might be next week before I get the Nobsound swapped out?

I'll keep you posted.

 

[TubeHiFiNut]

Got home before my Bride this evening and had a sliver of time so.......I got the Luxman back into the LR system.

There is absolutely no doubt that the Luxman is a much better match for the B&Ws. Wow.....

This is not to, in any way, denigrate the Nobsound. It's just not the amp to use with these speakers.

I'll definitely be setting it up with speakers that will be a much better match - like the University 6201 12" coaxials (AlNiCo magnets) in JELabs OB enclosures.

More to follow.

 

[Opa1]

The efficiency of the 6201's should be a better match.

 

[TubeHiFiNut]

The efficiency of the 6201's should be a better match.

I believe that they will be.

 

[ColinWonfor]

So which transistor is supposed to be "better"?

Please note 2N3055/2N2955 are made by many companies do not by a duff set avoid China, and far East devices, try and get the original from RCA or Harris.
Do not buy ever STC labelled devices, in the orignal device the Si was about 4mm Square and could easily run in the SOA (Safe Operating Area) at well over 100W, but the Si die in others are only 1mm Square, so smoke will happen.

Now also look out for 2N3772-3 in TO-3 this transistor make the the 2N3055 look like a toy.

Oh the RCA and Harris devices will manage 1MHz BW with ease the crap stuff maybe 100KHz

The reason I wrote this when I designed large linear PSU at 55V 100,000Amps we used 1000,s of power transistor and the new buyer trying to save money bought 100K of the crap transistor to save just a few old pennies.

 

[ColinWonfor]

Here's the PLH version. http://www.6moons.com/industryfeatures/zen/plh.pdf . The final version of the schematic is at the end of the article. It appears to be very similar. I'll have to print out the schematics so I can compare them.

It is still only a push pull design, SECA designs I think sound better, the Mullard CCT before JLH used a choke as constant current much like a modern design from Greece or Italy, but this are low power and the choke is huge and heavy.
Wireless World circa 1974 also did a design and our Noel Keywood also had a great bash at it.
Getting the PSU to be a very low impedance is the trick to the good sound and 50W-70W SECA I made sound better than some of the 300W I made.

 

[TubeHiFiNut]

Thank you, ColinWonfor

Appreciate the insight regarding the correct transistors to get.

 

[TubeHiFiNut]

Update on the "Nobsound Saga".

Something in the right channel definitely went bad. Sound out of that channel is badly distorted.

Douk has a replacement board on the way from China. I'll report back when we get the new board installed.

More to follow.

 

[TubeHiFiNut]

@Golden Gate ER was kind enough to desolder the bad board and solder in the new one - I told you how much I hate to solder.

I'll hook the Nobsound up when I get some time and report back.

 

[Opa1]

Good deal! Did he also adjust everything too?

 

[TubeHiFiNut]

Good deal! Did he also adjust everything too?

Don't believe so. We were both "on the run".

He did fire it up and nothing smoked.

Needless to say, I will be testing on some very inexpensive JBL 2045 bookshelf speakers.