Hoffman Amps Turret Lugs?

[Sherman]

Does anyone here have any experience building amps using Hoffman Amps turret lugs? Anything to watch out for?

I've been thinking of using them in my new project. It appears the neatness factor would increase by an order of magnitude over my p2p wiring.

I was thinking of running wires from the tube sockets to the lugs rather than soldering components directly to the sockets (except for the grid-leak resistor and possibly the coupling cap).

[Brian Beck]

These look pretty nice for a semi-production environment, but I use a similar, but, to me, easier approach. The problem with the Hoffman turrets for the DIYer is that tooling is required.

I bought hundreds of insulated stand-offs with turret tops and screw bases (either with a threaded hole or a projecting screw section). I just put them where I want them on a base board and screw them in. Just takes a few seconds. Want to modify the circuit later? No problem, just unscrew the stand-of and reuse it later. You can mount these on many kinds of bases: perforated plastic sheets, perforated metal sheets, perforated PC material. For prototyping, I use perforated Masonite like you’d use in your garage to hang tool hooks on. Not pretty but it works to prove the design. My stand-offs have Teflon insulation between the turret and the mounting base and come in many sizes. If you use only insulated base materials, you could use non-insulating stand-offs.

I prefer this kind of construction over PC traces because of the lower stray capacitance.

[Sherman]

Originally posted by Brian Beck
...I bought hundreds of insulated stand-offs with turret tops and screw bases (either with a threaded hole or a projecting screw section). I just put them where I want them on a base board and screw them in....

I prefer this kind of construction over PC traces because of the lower stray capacitance.

That sounds like a great idea. No need for specialized phenolic boards, no flaring tool etc.

I'll have a look around for the stand-offs.

[SY]

Brian, these sound great. What's your source?

[gingertube]

Sherman,
For the purposes of the newbies amongst us -

Did you really mean grid leak resistors or should that have read grid stopper resistors.
The grid stoppers are the ONLY things which NEED to be attached directly to the tube socket. In most cases all else can go on the turret lugs/standoffs.

Teflon insulation is the BEST - so the insulated standoffs would be great.

Brian,
I would also like to know where you got these things. prototyping would be so much easier with them.

Thanks,
Ian

[Brian Beck]

Guys, I wish I could give you a sure source of these things, but I bought them at a wonderful surplus electronics outfit in Orlando, Florida, many years ago. The place is called Skycraft, link below. If you're ever here in central Florida, drop the kids off at Disney World, and then drive yourself to Skycraft. You'll have more fun than they will. I don't know if they still have bins of these items (I bought hundreds of each of several different types).

I've seen these stand-offs in vintage military equipment gear, so there must be NOS inventories left, although many of them used phenolic insulation or at least something other than Teflon. Pete Millett described a similar approach in AudioXpress. Go to his site below, and download the PDF version of his AudioXpress preamp article. Look at photo 3 for examples of these terminals, and also look at the part sources listed at the end.

http://www.skycraftsurplus.com/index.asp

http://www.pmillett.com/lowmu_preamp.htm

[Sherman]

Originally posted by gingertube
Sherman,
For the purposes of the newbies amongst us -

Did you really mean grid leak resistors or should that have read grid stopper resistors.
...
Ian

You are right, I meant grid stopper. Sorry about that. I'm pretty much a noob myself so I may screw up terms from time to time.

As for the standoffs- I found some brass ones cheap but they will need an insulated board to mount them on, I'm going to try 1/8" Lexan. I also ordred a few zinc plated "cap screws" to go into the top of the standoffs and I'll try soldering directly to those. Should be interesting.

Another thought I've had is to just use 8 position terminal strips (the solder lug type not the screw "Euro" connector type). I just thought the lugs looked "cleaner".

[Audofile]

I've used many, but have been using turret lugs from www.turretlugs.co.uk for some time as they are so easy to rivet and are reliable.

[ArtG]

I just finished constructing a board using Keystone "Standardized Terminals" which are available from Mouser. Although Keystone offers many more terminals than Mouser lists, I dont see any screw type offered, only the flare type. I used #1509 which is a double turret with a hole through the center that I found to be very useful, since it allows a connection below the board and the ability to mount small parts or wires into the tops of the turret. All this allows parts to be mounted in sort of a 3D rather than 2D plane, resulting in a wider latitude of layout options and importantly, the ability to keep wiring runs shorter than can be achieved with either "tag boards" or conventional printed circuits. While the careful planning of the board layout is more work than simple point to point wiring, I feel the results are worth the effort.
I imagine that someone could find small sheet metal screws to attach these "through-hole" terminals to a board, although I had little difficulty attaching these flare type terminals, even on my first try. The flaring tool was about $11, as I recall, and using my small drill press as a punch press, I installed 30 turrets in about 30 minutes or less.

[jlsem]

http://www.diyaudio.com/forums/showt...211#post540211

In this picture I used three different types of turret terminals. In foreground are brown nylon versions of the Teflon types Brian is describing, in the center is a turret terminal strip, and on the ground buss are press-fit turrets for soldering to ground. I will post a similar picture of a pre-amp that uses the Teflon screw-in versions.

John