Dual layer eyelet boards

[Sonny ReVerb]

What is the purpose of the dual layer eyelet boards? Is the bottom board a 'blank' that just holds the wires in place? Are they sandwiched together or is there some type of spacer between them?

I've searched a bit for any info without success.

Example from Rob Livesey's site (#124):

[img:648:486]http://personalpages.manchester.ac.uk/s ... 124103.jpg[/img]

[heisthl]

IFAIK its reliability - yes they are just stacked on top of each other with no spacers. It helps keep the top board from vibration flexing and reinforces the mechanical aspect of the solder joints. Also answers the question of build order (i.e. you have to make the board with flying leads).

[David Root]

So, if you used say 1/8" G-10 you don't need that extra board and mechanically it's the same as if it were a turretboard (not to say the different layout wouldn't affect the tone). Same for the PS caps board.

[Sonny ReVerb]

Interesting. I hadn't considered the build order aspect. I haven't used eyelets before, just turrets. I usually populate the board ,then mount it and wire it up in situ. Thanks for the insight Henry!

Does routing the wires through the hole in the upper board just keep the wire from wandering? I suppose it helps relieve stress on the solder joint, as well. I've seen some amps use a similar technique where they route a wire up through a hole to a turret, but that was a single board.

[hbamp]

I use the extra board with copperside down and conected to ground.
This works like a shield between the board and wiring. I realy think it works out good to reduce some noise and hum.

[collinsamps]

The bottom board is required when chassis mounting (vintage fender) for ground isolation and when using the old phenolic boards it helped prevent warping after moisture was accumulated over the years. On standoffs if your board material is up to the task you don't need the backer board when building the board with flying leads, however if you solder eyelets after the install it allows you to do that without making a huge mess, having the solder fall through the eyelets, or god forbid short out eyelets under the board.

For cost saving there is no need to use G10, electrical grade fiberglass or anything expensive for the backer board. I've used masonite, regular phenolic, the old fish paper, or even 1/8th wood.

[mlp-mx6]

I have to think the wood would be a poor choice due to the effects of humidity. If you were is a southern coastal town for any length of time the wood would absorb a LOT of water and likely be quite conductive. That just cannot be a good idea.

[collinsamps]

Ampeg used blocks of wood(literally) for 20 years with no problems, fender boards have absorbed moisture from the envorinment since day one and are still going strong. There's 50 years of data to support the choice and that's enough for me. Of course I don't pour water in my amps and the chassis isn't fab'd out of screen door material al'a the polish submarine joke. To each his own.

[M Fowler]

I got some counter top laminent from Benoit and used that for my board in an 18w Plexi worked just fine in an old Estey organ amp chassis. I didn't want to put some thing too fancy in there.

[talbany]

Very early I rebuilt an old 60's BF Bassman head...amp sounded amazing and played it out several weeks...Later found out the G-10 absorbed moisture sitting in my basement and was actually reading a hi meg short...In fear of frying something myself included I bought some new board and rebuilt the amp part for part.. Just the board.. Installed the new one and amp didn't sound the same..I much prefer d the conductive board.. Go figure...Not saying the conductive board made the amp sound better but it certainly didn't hurt the tone..Go Figure,,,


Tony

[mlp-mx6]

Ampeg used blocks of wood(literally) for 20 years with no problems, fender boards have absorbed moisture from the envorinment since day one and are still going strong. There's 50 years of data to support the choice and that's enough for me. Of course I don't pour water in my amps and the chassis isn't fab'd out of screen door material al'a the polish submarine joke. To each his own.

I can't possibly argue with you, but being originally from Charleston, SC, I guess I'll err on the side of caution and stay with regular circuit board material.

All the best!

[David Root]

Later found out the G-10 absorbed moisture sitting in my basement and was actually reading a hi meg short

Tony

How did you determine that G-10 absorbed moisture? Did you weigh it before and after drying it out in an oven?

[talbany]

Later found out the G-10 absorbed moisture sitting in my basement and was actually reading a hi meg short

Tony

How did you determine that G-10 absorbed moisture? Did you weigh it before and after drying it out in an oven?

Don't be ridiculous!!

The Full Story..
Let me clarify...I am not certain it was G-10..It was the old style type fibrous type brown board ...I was using mostly turrets at the time..I had built an amp that I kept getting DC (scratchy) on the pots and couldn't for the life of me figure out why..Put a meter on the board and kept getting a high meg reading..Cut a piece off the board scratched the board and had obviously became conductive..I don't remember the exact reading but was enough to give me DC on my pots... That amp was built a month after the Bassman although the Bassman didn't have DC bleed ...I certainly can't say for sure it was moisture although I did keep the board took it out of the basement and didn't use it for quite a while kind of wrote it off..About a year later I went back and checked it with my Fluke and it read a dead 0..so I can only assume it was moisture..

Tony

[collinsamps]

I would bet that the most porous material ever used for amp boards will outlive carbon comp resistors when it comes to the absorption of moisture and eventually causing the bacon frying sound when used for plate loads. So when the purist are looking for board material that will remain moisture free underwater for life and then load it with vitreous coated carbon comps, realize that you could have used balsa wood.

[talbany]

I would bet that the most porous material ever used for amp boards will outlive carbon comp resistors when it comes to the absorption of moisture and eventually causing the bacon frying sound when used for plate loads. So when the purist are looking for board material that will remain moisture free underwater for life and then load it with vitreous coated carbon comps, realize that you could have used balsa wood.

I agree...Conductive boards are a very rare occurrence..In my case a freakish event.. I was not trying make a point,,Just sharing a weird 1 time event...and the fact that although the Bassmans board was slightly conductive still sounded amazing....This has never been a problem since although I don't build amps in my basement anymore..Long time ago I grow Mushrooms there now!!...


Tony