In the proces of finishing my Brown Deluxe I have the parts of the circuitry waiting here to assembly them on some new fiberboard in the near future. But…as I look trough all the parts laying around here it turns out that I might as well build a 5e3 Tweed Deluxe from them. That would be a nice spring project, would it not? My main Tweed Deluxe shown in the gear page on this website is now back to stock and sounds fantastic. So this 2nd Tweed Deluxe could be cool to do modifications on. I used to have this 2nd Tweed Deluxe which I sacrificed for the parts anyway, so the cabinet is still there, the chassis is there, pots, switches, fuse holder, pilot light and some small hardware are all to be found in the parts-box. I have all the components for the circuitboard except for the 5K and 22K 2w resistors in the power supply. I might need a new Power Transformer as the other unfortunately blew during recording. I need a speaker, jack inputs, a nice set of tubes and some small hardware. But that’s it! Yeah…Let’s do it! I am going to try to write about the pleasant building-proces and hope to give an insight view on the construction…feel free to comment!
Step 1: After cleaning the board with some nail-polish I dry-fitted all the components of the circuitry.
The resistors are carbon composition ones.
The two 56k as shown on the picture are not, but will be later.
Signal capacitors are Mallory 150’s, electrolytic capacitors are TAD.
The use of carbon comp. resistors for the so-called special mojo could be true or myth. But I like to use them when building a vintage style amp due to the possible drifting in value when used and harmonics they would add to the signal. The downside is that they can cause some noise and are known to fail sooner than for instance carbon film resistors. Anyway, Here is a nice article about carbon comp resistors. According to the article, the use of carbon comp would be good at the plate resistors only. For now I will try go carbon comp all the way first and see how the amp behaves. After dry fitting and cut to size, everything is soldered down leaving some room at the connections as later in the proces some wires will have to fit in there too. More solder is fed when these connections are made.
Some work on the deluxe again! Let’s go! The necessary parts are fitted in the chassis and the preamp section of the circuit is now wired with full carbon comp resistors, ceramic tube sockets and a silver mica bright cap. All value’s are stock until the amp is finished and working. For possible modifications, I’m thinking about a switchable cathode bias-value (250 Ohm to a for example 400-ish range Ohm to improve dynamic response and more) and perhaps a switchable tone-cap value (0,0047 to 0,0005 to cut the brittle edge).
According to the original schematic, the grounding of components as inputs, bypass capacitors and the filter capacitors is done close to the location of the components. That will probably work but may cause issues. Like in most amp designs and to minimize (idle) hum I try to tightly lead them all to a central grounding point, to the power transformer, meeting up with the ground from the net wire. Testing will show if I need to lift the input jacks and pots from the chassis.
The choice of 20 AWG for the circuity wiring doesn’t turn out to be the easiest after all. After connecting one end, bending the wire to the correct shape has to be done with a lot of tenderness and listening to Chet Baker as the thick wires are stiff and tend to break.
Next up will be the wiring of the power amp section and jack inputs…
And it’s finished! The project was abandoned for a while but after digging in again for a couple of nights it’s done! It turned out a new power transformer was needed after all. I went for a Hammond 290AEX to do the job. The rest was more or less done with leftovers from the tiny-bits box and a small order to achieve completion at least.
A couple of details regarding the circuit: The values of the filter caps are: 30uf for the main filter cap, 22uf for the screen and the stock value of 16uf for the preamp. The cathode resistor value is 250Ohms, the stock value as well. The plate voltage is kept at a very descent low 330v thanks to the JJ 5y3 rectifier tube. V1 is a EH12AY7, V2 a JJECC83s and the speaker is a Jensen P12Q reissue.
I performed the fairly simple artificial center tap to the filament wiring to get rid of most of the 60hz idle hum. The instructions to this and many other useful modifications can be found here: https://robrobinette.com/5e3_Modifications.htm
The finished amp sounds very nice, has a pretty tight low end, yet has a open lively sound and the early breakup it’s well known for. Sound clips and/ or video’s will appear in the near future. Have a great weekend and till next time…
Check out my other projects: http://www.aldospadaro.com/projecten/