• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

PCB or hardwire?

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Hi guys,

Do you have any experience to share about the pros and cons of PCB vs hard wire. For my previous projects ( mainly head phone amps with valves ) is used
Tag boards only. Now I have a hybrid head phone amp in mind ( as on the Headwize site ) which really asks for a PCB. But tube bases on PCBs? Any suggestions? :confused:

Thanks in advance.
 
Member
Joined 2009
Paid Member
You can get tube sockets for PCB mounting. I buy the ceramic ones on eBay.

For prototypes, I generally build point-to-point but my circuits usually end up being fairly complex so I've taken to label the prototypes DeathTraps. I much prefer a PCB layout. It makes it easy to build two identical channels or two identical amps. It also keeps the parasitics under control.

~Tom
 
For a single amplifier or any other device a PCB is expensive, needs to designed and manufactured. Usually the sensible minimum quantity to make PCB is some 5 pcs. Therefore a point to point is so popular in tube constructions. There is an other option. Use a vero-board or similar prototyping board which has 2,54 mm raster to accommodate op-amps and similar circuits. Then just make the wiring at the copper side of the board.
 
For a single amplifier or any other device a PCB is expensive, needs to designed and manufactured. Usually the sensible minimum quantity to make PCB is some 5 pcs. Therefore a point to point is so popular in tube constructions. There is an other option. Use a vero-board or similar prototyping board which has 2,54 mm raster to accommodate op-amps and similar circuits. Then just make the wiring at the copper side of the board.

Hi Artosolo,
That is actually a brilliant idea, but do the valves bases which tom mentioned fit on vero boards?

Regards,

Stef.
 
I have PCBs made for projects from time to time, typical cost is $150 for 100 copies.

Where on earth do you get PCB:s that cheap? I just ordered a couple of designs from iTeadStudio, and that set me back round 100USD. And that's China! And only 'round 20 boards alltogether.

PCB:s can be very expensive, if you order just a couple. Here in Finland a single board from a local shop is very expensive. The costs of making the films are around 50 euros a layer, so a single board will set you back anything in between 300 to 500 euros. Of course after that the boards themselves are much cheaper. I remember a production run of 250 boards being somewhere around 750 euros.

I have to say, that there are differences in quality between board manufacturers. I previously ordered a set of boards from a manufacturer in Bulgaria, and their quality does surpass the quality of the chinese boards from iTeadStudio. But there is a big penalty in price, also. For example, they use gold plating for pads in Bulgaria, whereas the pads on iTeadStudio boards are HASL plated. Gold does give better shelf life and better solderability. Also the silkscreens and solder masks are of better quality on the Bulgarian manufacture.

Regarding PCB vs point-to-point, I have no opinion on the sound. I've never compared if I could hear any difference in sound between the same amplifier as a hard wired and a PCB version. Mainly just because I'm lazy, and have no time to make two versions of the same amplifier. Some do appear to think that point-to-point wired amps are superior, but I have no idea whether or not there is any facts backing their claims. I'm open to changing my mind if proven wrong, but generally if the design is complex enough, or has to be replicated many times, PCB in my humble opinion does make too much sense. The layout is so much easier to design cleanly and everything is easier to mount with short signal paths. Granted, point to point wiring when implemented extremely carefully can yield even shorter paths. But more often than not the implementations are more reminiscent of a bowl of spaghetti than clean PCB layouts. And on top of that you can get reliability problems of failing solder joints if you haven't secured heavy components properly.

I do make amps both ways. A carefully designed board can save you a s---load of time when assembling the final product. But they give less possibilities of changing the design afterwards if you're just prototyping. When you're completely certain that your design works, maybe PCB would be the best way to go. At least it will make it easier to replicate your design when your friends want ones of their own. But if you're just prototyping a fairly simple design, I suggest a carefully implemented point to point construction. Since you probably have fudged up in the design process anyway, you can more easily change the design if necessary.
 
I do the same thing. I'll make building blocks - a PSU regulator, a CCS board, a tube socket board, LED array boards, etc. PCB runs of 10 are inexpensive (I use SeeedStudio for the PCBs and FreePCB for the design) if you can fit one or multiples in the prescribed size limits. Plus, one mistake won't require re-doing the entire design. PCBs are great for kits or production runs, but I can hardwire faster than designing and stuffing a PCB. Just don't stick you hand in it while running!
 
What PCB material have you used?

I normally use FR-4 (fiberglass).

For a single amplifier or any other device a PCB is expensive, needs to designed and manufactured.

Actually, Batch PCB will do single PCBs for rather reasonable prices.

Use a vero-board or similar prototyping board which has 2,54 mm raster to accommodate op-amps and similar circuits.

Yep. That's certainly a good option. If you use chassis mounted tube sockets, get a big enough piece of Vector/VERO board mounted below the sockets, and drill holes in the vector board to access the tube sockets, you can make a pretty rugged setup. I don't know if that sentence made any sense at all. I can see it clearly in my mind though... :) PCB mount sockets won't fit directly on the Vector board, but if you make some slots for the pins with a needle file you can make it work.

I make PCBs in my garage using a toner transfer process and an etchant made from household chemicals. Easy as pie. I've done that since I was in 5th grade (so some 25-ish years now)...

~Tom
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.