5E8A build

[David Root]

With a Goldtop with old HBs in it ('65), what would your speaker choice in a combo be?

I'm looking at doing a head right now, to use with my Altec 417s, but just in case I weaken and go for the TOTAL TWEED experience.....

Old original cone P12Ns? Ditto but C12Ns? One of each? Put the Altecs in the combo?

I have heard that Keef uses Celestions of some kind in his 5F8s, but that's a bit different amp. Is a Celestion suitable for this amp and if so which one(s). Maybe G12-65s? The only Celestions I have are G12 Blues and black backs, and they're happy where they are currently.

[David Root]

Looking over the original 5E8A schematic and layout from Schematic Heaven, I noticed that the layout shows a 47pF ceramic brite cap across the treble pot, but the schematic shows nothing there. Like the Cheshire Cat, it's there and not there.

Which is right?

I've never seen an original amp close up, and the only pic I have is too low definition to be sure, but it looks like there is a ceramic cap on the treble pot.

Also, anyone have a good pic showing the rubber grommet mounting on the sockets?

While I'm at it, the layout seems to indicate that the 250pF treble tone cap is a domino type, which sounds right for the period. Is it?

[Cliff Schecht]

I put in the treble cap. I use your standard silver mica cap because I don't like or even own that many ceramics. I'm surprised I didn't use polystyrene there but neither will have a great "tonal" contribution (i.e. coloring the sound).

A quick googling shows that Fender did use domino caps in some places but IME these don't sound any different than your newer manufacture parts. The charm is in the age and maybe something does change over time but the difference between and old and new mica cap isn't vast, the newer stuff is somewhat sturdier maybe. The only reason I would use dominos is because I have some high value ones that could be used as coupling caps, but I haven't tried this yet.

I honestly didn't even know Fender used rubber mounted sockets until I was corrected on another forum. There is a guy on TDPRI named "Inventour" that has a superb collection of vintage Fender amps in *perfect* condition (many with the hang tags, factory cover and original e-caps). He has a high powered tweed Twin that he has posted some detailed gut shots of (cleek here!) and might have a 5E8A that he can show off (although I don't think I've seen it). Pretty sure the dual rectifier Twin is one of the rarer tweed amps.

[David Root]

Thanx a lot Cliff, that really helps. I think I have a 250pF domino somewhere, I just hope it's the right voltage.

[Cliff Schecht]

If not I can dig one or two up for you.

[David Root]

Thanx Cliff, I found three of them, 300V, orange dot on lower row left, so I'm good!

I've been digging a bit deeper into this amp and I have another question.

Did Leo change his wiring gauges between the tweeds and the blackface amps? Reason I ask is I have a bunch of the cloth covered wire from a '67 AB165 that I deconstructed to build my '70s ODS and my Bluesmaster. The heater wire is 20 ga and all else is 22 ga, both solid of course. I would like to use that in my 5E8a build because it "fits" better and looks cooler than new wire. But if it's not the tweed correct gauges I might not use it.

[Cliff Schecht]

Now there's one I'm not sure about. I honestly didn't know whether Leo used solid or stranded until you mentioned it. I've never worked on a real tweed, brown or blackface Fender so I can't comment with experience but from what I can tell in pics the wire does get smaller in blackface amps. Did he switch to stranded during the brown era or blackface era?

[David Root]

The wire I got out of the AB165 Bassman is solid. That is a late blackface amp, so I doubt any BF amps used stranded wire. I would bet the early SF amps would be the same.

I have a brown Deluxe and reverb unit. I'll take a look at the reverb unit, it's easier to move around than the Deluxe.

[Gibsonman63]

My BF Fenders have solid core wire.

[David Root]

Checked my '62 6G15, same wire as the AB165, solid 20 ga heaters (.032 dia.), solid 22 ga. otherwise (.025 dia.). So brownface and blackface are the same.

[David Root]

Got these off EBay today. Guy wants $9K for it! As you can see all of the electrolytics have been replaced at one time or another, no surprise there.

But a 500uF cap on the bias supply????.

Note also the 470R 1W screen resistors, can't tell if they are original or not, they are not in the Fender schematic or layout. I'm going to put those in mine.

As I thought from the layout dwg., the 250pF treble cap is a domino silver mica type. The 47 pF ceramic cap in the layout is clearly visible too here.

But what is that connected between the plate and cathode of the PI stage?? Looks like it might be two tiny domino caps in parallel. I know Fender used a 47pF cap across the plates of an LTP PI to kill parasitics, would this be the same deal here, even though this is a simple split load PI?

[diagrammatiks]

that's a cathodyne right?

if so you can snub them between the plate and cathode.

[David Root]

That's right, cathodyne. Not a factory mod, I would assume, as there is no evidence of it on either the schematic or layout I have.

Still trying to see those tube socket anti-vibration rubber O-rings people said are on the tweeds, but can't make 'em out, even though these are the best gutshots of a real 5E8A chassis I've seen so far. I bought some little O-rings that fit nicely over a #6 bolt.

[diagrammatiks]

last time i was looking angela had most of those parts.

a bit pricey but its all there in one place.

did they use the wavy sockets at that point?

[David Root]

Can't tell about wavy sockets from these pics but I know what you mean.

BTW I did decide to do the 5E8A as the combo. Having an antique pine cab made now, from wood used to build a grain elevator in Wisconsin in 1883. Not cheap but I bet those old P12Ns I got will ring like bells in it!