Preamp PCBs arrived from JLCPCB. Thumbs up!

[BluegrassDan]

My first ever run of PCBs arrived from JLCPCB. Quality looks good. Everything works and sounds great. Shipping was very fast. They arrived several days early, maybe a week from upload to having them on my porch.

There is a tube preamp card and an input switch card for 48v, pad, polarity, and HPF. It is silkscreened on the front and back for reversibility and can be oriented all sorts of ways depending on the front panel design.

Still waiting on Cinemag to send over the input and output transformers, which are likely several weeks away. In the meantime, I have a couple wired up.

As always, I appreciate everyone's input on this forum along the way these past few years.

 

[Ricardus]

I love JLC. Killer service and pricing.

So tell us more about this preamp.

 

[BluegrassDan]

It's the latest (and probably final) iteration of what started about 5 years ago. It's a three-tube arrangement, two 6072 gain stages with cathode followers and a 12BH7 WCF output. I've gone on and on about it getting help from virtually everyone here on the forum. It's been good for my mental health (and probably bad for everyone else's)!

 

[ruffrecords]

Well done Dan. Good looking boards. I am curious about the PCB mounting tube sockets you use. The only ones I have found that take shields all have incredibly tight pins. So much so I find it extremely hard to get tunes in and out.

Cheers

Ian

 

[BluegrassDan]

Ian,

These first prototypes boards use a standard chassis mount Belton micalex socket with shield. The socket is hand wired to numbered hole-terminals on the board.

I have already made some minor edits to the board, and I plan next to try the Belton shielded sockets with PC pins, which require a 6.4mm standoff to mount them above the board. I'll report back once that happens, which will probably be a few weeks.

Having been repairing guitar amps for folks, I find the Belton sockets have a more consistent and easier tension than the ceramic Chinese sockets.

 

[ruffrecords]

I have quite a few of the Beltons. I find their sockets to be very very stiff. I don't use them any more. I am happy to send them to you FOC if you would like them.

Cheers

Ian

 

[Ricardus]

It's the latest (and probably final) iteration of what started about 5 years ago. It's a three-tube arrangement, two 6072 gain stages with cathode followers and a 12BH7 WCF output. I've gone on and on about it getting help from virtually everyone here on the forum. It's been good for my mental health (and probably bad for everyone else's)!

Will you be selling the boards down the road?

 

[Ricardus]

I have quite a few of the Beltons. I find their sockets to be very very stiff. I don't use them any more. I am happy to send them to you FOC if you would like them.

Cheers

Ian

What are you using instead of Belton?

I've used Belton and they do seem tight at first, but that micalex stuff is hard to beat.

 

[BluegrassDan]

Will you be selling the boards down the road?

Lord, I dunno. I move pretty slow! If anyone was interested in the little switch board I'd entertain it.

 

[Ricardus]

Lord, I dunno. I move pretty slow! If anyone was interested in the little switch board I'd entertain it.

I'm interested in the project!

 

[ruffrecords]

What are you using instead of Belton?

I've used Belton and they do seem tight at first, but that micalex stuff is hard to beat.

I have been using individual 1mm gold pin sockets in all my designs so far. These are fine for static operation but not for transport or mobile use. I wanted to create some robust tube mic pres for use on the road so they need slightly tighter sockets and provision for screening cans. I thought Beltons were the answer but they are unusable with current production tubes which seem to have slightly fatter pins than NOS.

Cheers

ian

 

[oscarhuang]

I am always with JLCPCB.

 

[Ricardus]

I have been using individual 1mm gold pin sockets in all my designs so far. These are fine for static operation but not for transport or mobile use. I wanted to create some robust tube mic pres for use on the road so they need slightly tighter sockets and provision for screening cans. I thought Beltons were the answer but they are unusable with current production tubes which seem to have slightly fatter pins than NOS.

Cheers

ian

I've only used the Belton, and they are super tight the first time, but after that insertion it seems fine.

 

[ruffrecords]

I've only used the Belton, and they are super tight the first time, but after that insertion it seems fine.

OK, I will give them another try.

Cheers

Ian

 

[Ricardus]

OK, I will give them another try.

Cheers

Ian

I did have to be super careful though. They were often mounted on 1.6mm PCBs, and in those cases I often put my hand behind the socket to reinforce for insertions. Always best to do multiple insertions with a spare tube before you mount them.

 

[BluegrassDan]

The Beltons are a bit tight at first, which is troublesome for the builder who is plugging and pulling. Once the thing is racked up and stays put for years, I think a little tight is better than a little loose.

 

[ruffrecords]

The Beltons are a bit tight at first, which is troublesome for the builder who is plugging and pulling. Once the thing is racked up and stays put for years, I think a little tight is better than a little loose.

Are you using current production or NOS tubes?

Cheers

Ian

 

[BluegrassDan]

Both. You're right that the current production tubes do take some extra effort to install.

 

[ruffrecords]

Both. You're right that the current production tubes do take some extra effort to install.

That's good to hear. I was beginning to think it was just me.

Cheers

Ian

 

[fazer]

I’m interested in the switch boards for 3 mic pres I have Could use 3 to 6. Thank you