Tweed Tremolux 5E9-Advice Sought

[sgelectric]

A friend brought me a Tremolux to check out for him.Amp has been recovered,has an 80w Fane ceramic in it but is otherwise pretty much stock.Tube chart specs it as a 5E9 FH sn 01075 and specs a 5U4GA.It dates to August 1956.
http://www.webphix.com/schematic%20h...5e9a_schem.pdf
This is the only schematic I have access to although I hear the differences between it and the 5E9 are minimal.

Questions:

The B+ is high, as expected, at 430vdc.Subbing a 5Y3 drops it to about 407.Would this be a good idea?

The first dropping resistor is a 4300 ohm rather than the 2500 in the schematic.Has anyone seen this in other stock amps?Good idea?

The previous owner has a 12AX7 rather than a 12AY7 in the first position.Is this simply a matter of taste?

There appears to be asbestos covering most of the back panel.How is this best dealt with?

The amp works fine but the main filters and output bypass cap date to 1974.AC ripple at first filter measures at 6vac. .Preamp/PI bypass caps are original.My intention is to replace all the electrolytics and any resistors that are way out of spec.I want avoid doing anything that would detract from the amp's value.

Any advice/comments/suggestions from those more familiar with these amps would be greatly appreciated.
Thanks, Steven

[Chuck H]

It's pretty well understood and expected from what I've seen in the vintage market lately that electrolytics and out of spec resistors must be replaced in these amps. Another thing that is not only expected but appreciated is changing to a properly grounded three prong AC cord. Do be careful with the old cord so that it can actually be put back in if an investor wants the amp that way. Don't worry about the caps since they're not original now. I think your out of the investor market with a re-cover anyway and anyone intending to use it will appreciate the amp being in playable condition rather than original.

Go ahead and use the 5Y3. No harm, no foul. Current production 6V6's can take the higher voltage anyway but dropping it with the 5y3 will sound more original.

Parts other than what you see in the schematic went into Fender amps all the time. Especially in the early years. A running gag among Fender employees was that the company tag phrase should be "We don't make 'em like we use to... And we never did." Don't worry about that 4300 ohm resistor (unless it has drifted or otherwise failed).

A 12ax7 is an easier tube to come by (though a 12ay7 isn't that hard to find) and a 12ax7 of course has higher gain. Looking at the schematic I can't see any reason not to put a 12ax7 in there if you like the sound of it.

[sgelectric]

Chuck, Thanks for your reply.
A three prong cord was already on the amp when I got it albeit with a switched hot and a fused neutral.I'll correct that.
I may just cover the asbestos with a thin sheet of aluminum.
I may have some rattling with the "floating" baffle.My understanding is that these were thinner than a "standard" baffle.I'll check it with another cab.It may be because the Fane is quite a bit heavier than the original Jensen.
I have some 12AY7s so I'll let the owner decide what he prefers.

Thanks for sharing your experience with these amps.

[Chuck H]

IIRC the one I worked on had a 5/8ths baffle. So that's pretty thin. But it seems to hold up on the tweed Bassman with 4x10's so... If it's not overly fatigued your fine just tightening screws. If you need a new baffle marine grade plywood in 1/2" (which actually measures 5/8ths) is a good quality sub. I'll bet the three prong cord was put in when the old filters were changed out. That would be pretty concientious for 1974.

Cheers

[Tom Phillips]

IIRC the one I worked on had a 5/8ths baffle. So that's pretty thin. But it seems to hold up on the tweed Bassman with 4x10's...

My notes from measuring original 5F6A baffle boards record that they are 9/32" thick. Or should I say 9/32" thin. The edge is twice as thick because of the added strips that space the grill cloth away from the baffle board.
Cheers,
Tom

[Rick Erickson]

The asbestos strip should be clear-coated with spray lacquer, enamel or varathane. Beware of the dust inside the chassis as it is probably loaded with Asbestos powder. If the amp has yellow Astron coupling caps, or wax-paper they are probably leaky and will affect biasing of subsequent stages. The blue axial coupling caps Fender used rarely fail and should be left alone unless proven bad. Orange drop caps should be illegal in Fender rebuilds, with few exceptions. Don't believe everything you read about "magic" resistors or capacitors. I recommend replacing ALL or the resistors and electrolytic caps. If the customer doesn't want to do that, then adjust down with the understanding between you and the customer that you can't guarantee the performance or reliability of said amp with the originals left in it. Of course you must do routine maintenance - cleaning and securing, soldering, remove death cap etc.. Do it right and both you and the customer will be very happy with the end result.

[EFK]

If orange drops are a no-no, what should one use to replace the blue molded caps? It's my understanding that they are polyester film, not metalized but polyester film and foil. Concrete info is tough to come by, but I thought the orange drop 225 and 6p series were poly film/foil as well. I know they sound good, at least I think they do, and they don't cost a fortune for a pretty label.

[sgelectric]

Thanks for the replies.
I just pulled the amp out of the case and discovered the OT is non-original.It's a Merit A2905 universal output.My research shows it to be rated at 24watts,70ma primary.Suggestions for a possible replacement?

Rick, The amp has the original yellow Astrons.I will check these.What would you recommend as replacements?The only non-original caps I see are a couple of silver micas in the oscillator circuit.
Thanks for the heads up on the dust inside the chassis.I will take your advice about sealing the asbestos.

Thanks again to all who have responded.

[EFK]

I think those yellow astrons are polyester as well, although I;d love to see some educated verification/contradiction of that.

[sgelectric]

Would it be a bad idea to boost the main filter cap to 40mf? Just checking..........