Fender 5E3 Deluxe Build

makepeace · 2010-08-23T19:51:36+00:00

Hi guys ? Within the next few months I'm going to be building a tube amp based on the 5E3 circuit and layout, with a couple of mods. The pre-amps, phase inverter and power stage will be stock (with a 12AY7 and a 12AX7 in the pre-amp unlike the two 12AX7 in fenders '57 reissue). My aim is to substitute the single control Fender tone-stack with a two control James stack, and to use a 5Z4 rectifier to start off with (its a cheaper 5Y3 workalike). Due to the James stack, it will probably have a single channel. James Stack: For the speaker I plan to use a Celestion G12-K80 (glowing reviews from Alan and Karel) to start off with, with the prospect of upgrading to a Greenback in the future when the budget is bigger ?. I will be getting the components and speaker from Karel, who has been excellent so far with helping me out (thanks Karel ?). The cabinet I will be building myself out of laminated meranti or pine plywood board with joists on the insides of the corners (can't be assed with finger jointing..). I'm thinking about a TV/Narrow Panel cross. It'll have the TV front, but with the Narrow Panel width and height and the angled front. Either that or it'll end up as a Narrow Panel. I quite like the aesthetic of the TV, but the functionality of the Narrow Panel (angled speaker does wonders for tone) is tops. I'm afraid that an angled TV might look funny ?. Also thought about a normal TV with an angled speaker board.. Opinions on TV vs Narrow Panel vs TV Panel vs TV angled speaker board? ? I'm still debating in my mind whether to cover it in Tweed or with one of these nice imitation leather fabrics: http://www.ugfabrics.co.za/swatchBooks/hides/Default.html. I quite like that white alligator pleather :-[. I would like your guys opinions regarding the traditional tweed vs pleather. I'm quite a purist, and would never.. retro-cover, if you will - an old amp, but seeing as this is my own build, I think it could be a cool touch ? Grill cloth will be either Mojotone's Gold Striped Oxblood: or the old brown cloth (used on the TV): This will depend on what looks good with the ultimatum of the covering material story. Ok, now for my first objective question ?. Does anybody happen to know, or would anyone be able to measure for me, the inclination of the front of a Fender combo? First prize would be the '57 Deluxe (but I'm sure any angled Fender combo will do). I'm just looking for a rough measurement so I can get designing the cabinet. Cheers, Jono

TomCat

The 50 uF Cap is the main storage cap before the choke. For an EZ-81 50uF is about as big as it can go before instability/oscillation occurs.
All other storage caps will be after the choke (usually 20uF)

EZ-81 is a great tube recto, but getting rather scarce (and therefore expensive). I have a Mullard EZ-81 in my 8w-SE and it works great.

makepeace

thanks tomcat. what effect does making it bigger have on tone? and what would be the biggest one could go with a 5Y3/5Z4?

TomCat

Not sure about tone and the first cap but I do know that my amp is really warm sounding. I have a 50uF into a 10H choke and then three 20uF after that. Very Fender but with a BIG choke.

I believe that the larger cap will improve bottom end in that more current can be delivered quickly when needed (usually at lower frequencies).

Unfortunately I don't know the other recto tubes so cannot comment much there.

In my amp I'm using:
V1 & V2 : JJ Ecc83
Recto: Mullard EZ-81
Power: Electro Harmonix 6CA7

Gearhead

The tone improvements one would expect from a big cap before a choke would be less noise from the net coming through. A choke resists changes in current so it does not make sense that a bigger cap in front of it will make it notably easier for the amp to deliver lagre amounts of current quickly; this would have to come out of the caps after the choke.
Making caps bigger will draw a higher peak current upon switching the amp on, so in recto tube data the maximum cap size is mentioned (your answer about the 5Y3 is in the datasheet). A choke will limit this initial current, so caps behind the choke can be relatively big without killing the recto. Since they also affect tone more than caps before the choke, I would recommend having similar capacity before and after the choke. One way to compare this so called 'pi-filter' with a cap-only in terms of startup peak is to simulate, so you know what you are doing to your poor little rectifier.

TomCat

Good point GH........Never thought of that.....But then with my current state of Bronchitis...(two weeks now)......I'm not thinking about much, or with much..... ??? ???. The first cap would primarily be a filter to smooth the Recto tube....

makepeace

thanks for the info gearhead and tc. the max cap size for the 5Z4 seems to be 32uF. So I'll have 16uf to play around with.

came up with this whilst messing around in corel.

still needs a little fine tuning.

makepeace

just ordered one of these https://taweber.powweb.com/weber/12a125a.htm in gold :dance:

Gearhead

makepeace wrote The max cap size for the 5Z4 seems to be 32uF. So I'll have 16uf to play around with.

I would then go for 25uF - 5mH - 25uF and see if it arcs upon switch-on. Don't be shy ?

makepeace

ok, expressing my total n00bness here. what is "arcing" in this context? as far as i know, arcing generally means bad :-[

MikeM

Can vouch for this making a big diff. Ok anyone know about effect on tone? Considering fiddling with a bfdr supply. Usually 32uf (OT) - 5h - 16uf (screen).

I want better filtering without tightening it up too much. Thinking of going, 18uf - 5h - 36uf (ot) - resistor - 12uf (screen)

Think that'll still get me some nice sag with better filtering..

Gearhead

@makepeace: if the cap is too big the current inrush into the cap will ask too much from the recto tube. It is supposed to conduct through electrons emitted from the cathode, but if those are not enough it will just create a nice lightning effect inside the recto. I used to call my hifi amp sparky for this very reason, the old recto tube in that thing always made switching on into a purple experience.
@Mike: unconventional but might be a good idea. Would like to know what the guru thinks of that?

makepeace

hopefully the guru will stick his head in on this one ?

ok i get that gearhead. thanks. is it an entirely bad thing if it sparks? or just not ideal?

Gearhead

The arc is bad for the cathode coating apparently... No tube lives forever though. AC30s eat output tubes like there's no tomorrow because of very hot bias and still everyone loves it. You might think that a good sounding design is not necessarily a sound design...

makepeace

Gearhead wroteYou might think that a good sounding design is not necessarily a sound design...

Insightful.

Sweet thanks for the replies. I'm going to go with the standard power filtering first, and fiddle once everything is running soundly.

The action will be starting soon, as I wrote my last exam yesterday. Already done some stuff for the cab of which I'll post pics just now.

makepeace

Knocked up these this evening:

1st year Engineering helping me along my way ?

makepeace

Created these this evening.. not a lot of fun, especially when the only tools i had at my disposal were a radial arm saw and chisels :-\

rikus

The fun has started!!

Really nice work so far! I'm looking forward to seeing it progress!

Good luck, have fun and don't rush it! ?

makepeace

Thanks ?

Just finished putting the cab together:

Things are going rather smoother than I thought 8)

TomCat

When you prepare well and have the right tools...it usually does.. ?

makepeace

TomCat wrote When you prepare well and have the right tools...it usually does.. ?

Too true.. I was very nervous about the box jointing. Its not something I've ever attempted, and I don't have a dado stack and a table saw with a big enough arbor. So I'm glad it worked out with the chisels ?

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