Amp Build: Brown Note 18Watt Lite IIB

[duhvoodooman***]

Coming along nicely, Tung! Looks like you should be ready to apply the electrons shortly. Wait a minute, I shouldn't use a word with "short" in it....

[tunghaichuan***]

Coming along nicely, Tung! Looks like you should be ready to apply the electrons shortly. Wait a minute, I shouldn't use a word with "short" in it....

So far this has been a fun project. The only downside is that I haven't had a chance to work on the Triboost pedal.

Duhvoodooman finished the enclosure for my Triboost pedal and it looks fantastic :

tung

[tunghaichuan***]

Wiring, Part 1: Preliminary Stuff

Pix here:

http://www.diycustomamps.com/images/...te/wiring_pt1/

This morning I did some preliminary work on the chassis to get it ready so that I can wire the circuit.

The Edcor output transformer has quick-disconnect tabs rather than flying leads so the first order of business was to make and attach flying leads to the OT. I found some quick disconnect connectors at McMaster-Carr when I was investigating using Edcor's transformers. I also bought some 600v, 20 ga. stranded wire in three colors: blue, brown and red. These are "standard" colors for plate and center tap leads on push pull transformers. The black and yellow wire is 300v, 18 ga. for the speaker leads. The quick disconnects use a dual crimping connection to hold the wire onto the lead.

The Edcor OT is slightly underrated for this application at 15w. The circuit puts out 18 watts, as indicated by the name of the circuit. Another thing I don't like about the Edcor OT is the lack of insulated flying leads. Using quick disconnects is inherently unsafe as there at least 300v on the plate and center tap leads. In one of the photos you'll notice that there is some red heat shrink covering two of the unused tabs. These tabs are ultralinear connections which are usually used in hifi amps. However, a few guitar amps have used UL taps most notably some Fender amps from the early 70s and some modern Dr. Z amps. There is also high voltage on these leads as well hence the heat shrink.

Once the leads are connected to the OT, it is a matter of twisting the black and yellow speaker jack leads and threading them through the grommet in the chassis. Then braiding the blue and brown plate and red center tap leads and threading them through the chassis. The wires are put into their proper places on the inside of the chassis as they they will be covered by the eyelet board and will be hard to get to.

The next step is to install the eyelet board. First I put the threaded hex standoffs in the chassis with lock washers to keep the board from vibrating loose. Next the board is put onto the standoffs and bolted down with machine screws and lock washers. I keep most of the machine screws loose until I line up the board to make sure it is positioned correctly.

Now that the board is installed, I can proceed to soldering all the flying leads into the circuit to finish up the amp. At this point I would estimate that the amp is about 50% done.

Stay tuned for more wiring.

tung

[duhvoodooman***]

Tung, any further progress on this amp build?? Dying to hear a clip from the finished product. C'mon, man--your adoring public awaits!! :

[tunghaichuan***]

Tung, any further progress on this amp build?? Dying to hear a clip from the finished product. C'mon, man--your adoring public awaits!! :

I really need to start the wiring. I was going to start last week, but I wanted to build the Tribooster. Which reminds me, I need to post a pic of the guts.

Tomorrow is my day off, so I'm going to try to get some work done then. :

tung

[Ch0jin]

Well, I started out with the best intentions... Just have a quick scan over the new threads over a coffee... Then I start reading this thread. Close the office door and don't move till I got to here haha.

Love the amp/fx build threads!!!!

Cant wait to see and hear more about this one as I've been psyched to build my own lower power tube amp for ages now. I'm even considering an 18W from ceriatone.

[tunghaichuan***]

Had a chance to start on the wiring this afternoon.

Some pix here:

http://www.diycustomamps.com/images/...te/wiring_pt2/

I started with wiring the power supply. First I wired the rectifier tube socket. I decided to use a 5V rectifier to take advantage of the 5V winding on the power transformer. Normally, an English circuit like the 18W would use a 6V rectifier such as the EZ81/EZ80/6CA4.

Next was the standby switch. This is merely a switch to interrupt the B+ from the rectifier to the first filter cap in the power supply.

After I got the can capacitor wired. This is kind of a PITA, as the solder lugs had several leads stuffed in them. This layout is a bit different that what I'm used to. Normally, all the filter caps are on the eyelet board. In this case, two of them are mounted on the chassi in the capacitor can. The other two are on the board. A nice feature of this design is the 200K ohm resistor to ground, which bleeds off the B+ when the amp is turned off. Caps can and do store a charge, so this makes working on the amp safer.

Finally, I got the IEC inlet, on/off switch and screen resistor wired into the circuit.

It looks very messy now inside as I have not cut any of the power transformer's wires to length. I like to leave them their original length until I finish and test the amp and get it working right. Then I will clean up the wiring and try to resolve noise issues, if any.

Wiring can be very tedious so I like to do it in small chunks. I got through today's wiring with a minimum of cursing and swearing

The next stage of the wiring will be wiring the filaments. I hate wiring the filaments It is my least favorite part of amp building, although this probably won't be too bad.

After that, the power amp, preamp input and output jacks, volume an tone controls, and then the gounds. Once I finish the grounds, the amp will essentially be done. The only thing left to do is fire it up and make sure it works right.

Stay tuned...

tung