Amp Build: Brown Note 18Watt Lite IIB

[tunghaichuan***]

Update:

Got the face plates ordered yesterday. I made a few changes to them to make the labels easier to align. Both plates cost me $33.75 shipped. Jeanne at BNP Lasers said that they'd be on their way by next week.

When I get the plates I can finish the chassis and then move on to the wiring.

EDIT: Got an email yesterday (9/27/08) from Jeanne at BNP Lasers, the face plates have been shipped out USPS Priority Mail. I'm hoping to get them by Weds. maybe sooner.

tung

[tunghaichuan***]

Finishing the Chassis, Part 2

Pix here:

http://www.diycustomamps.com/images/...e/chassis_pt2/

The face plates arrived Monday night, a couple of days before they were expected. My first thought was that they looked great. BNP Lasers does a good job. My second thought was: damnit! I made the holes for the volume and tone pots a little too big. The Alpha pots I'm using are 5/16" diameter and I specified 3/8". Slightly too big. One function of the face plate is to center the components. The holes in the chassis can be a little bit bigger than the component and having a face plate fixes this. So I had to measure very carefully to get the holes for the two pots in the chassis concentric with the holes in the face plate.

Tuesday morning I spent about two hours finishing the chassis. First, I fitted the front face plate. It was just a matter of taping the face plate onto the front of the chassis, tracing the holes with a fine-point Sharpie, running a center line down the front of the chassis, measuring and marking the locations of the holes with a tape measure and locating the center with a square. One I got the hole locations marked I used a center punch to mark the hole and drilled a pilot hole with a 1/16" bit. Then I drilled out the hole to the correct diameter with a stepped bit. The volume and tone pot holes came out great. The pilot light hole had to be drilled out a bit bigger to get the pilot lamp assembly to sit in the face plate hole correctly.

Once I got the front face plate done, I moved onto the back face plate. The back face plate has a rectangular hole for the IEC inlet. This is the first time I've used one and it looks much neater than drilling a hole, using a grommet and knotting the cord inside the chassis. I made a template out of 3/4" MDF using the hole in the back face plate as a guide. I roughed out the hole using the template taped to the chassis with double-sided carpet tape. I removed most of the material in the hole with a drill bit and further cleaned it up with a jig saw. I then used my laminate trimmer with a top mounted bearing on a flush cutting bit to cut the hole to size. Finally I used a file to clean up the corners. The hole in the chassis is kind of rough, but that is okay as the IEC inlet and back face plate cover it up. It came out great for a first effort: centered and aligned.

The other two holes were drilled out in the sam manner as the front plate: marked, located with a center punch, and drilled out.

Next I finished drilling the holes in the chassis to mount the chassis mount capacitor can and the tube sockets. With these it is a matter of using the socket it self to locate the holes, marking them with a Sharpie, locating the center with a center punch, drilling a pilot hole, and drilling them to size with the correct size drill bit.

The last step was attaching all the components to the chassis: the transformers, the front and back components, the tube sockets and the cap can.

The next step will be to start wiring. First I will need to attach the leads to the output transformer as it has quick disconnect terminals instead of flying leads. Once this is done, I can install the eyelet board and begin wiring the circuit.

Stay tuned.

tung

[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

[duhvoodooman***]

Looking good, Tung! : Getting close now....

[M29]

Sweet Tung, well underway! I notice you have the rectum fryer upside down. Just kidding, awesome work indeed

[luvmyshiner]

It's been awhile since I caught up on this thread. WOW! I can't believe how great it's looking Tung. Can't wait to see the finished product.

[tunghaichuan***]

Guys,

Did some more minor wiring this morning. Got a few things corrected that needed to be and started the filament wiring. Filament wiring is my least favorite part of amp building.

Thanks for the kind words, but it is starting to look like a rat's nest in there. It's not the cleanest build I've ever done.

This one is:

http://www.diycustomamps.com/images/...prin7_guts.jpg

That was built for a friend of mine and had to be absolutely perfect.

I hope to get some more wiring done this evening.

tung

[M29]

Tung,

Just curious on your friends build. Did you need to put shielded wire on the inputs or just did it in case of squeal? I had to use them on one amp but later on I took them off and it worked fine, can't figure that one out. This has been a touchy area on some of my builds.

Beautiful job:

M

[tunghaichuan***]

Tung,

Just curious on your friends build. Did you need to put shielded wire on the inputs or just did it in case of squeal? I had to use them on one amp but later on I took them off and it worked fine, can't figure that one out. This has been a touchy area on some of my builds.

Beautiful job:

M

Again, thanks for the kind words.

I built the amp with shielded wire just to make sure that it was dead silent. I wasn't taking any chances with that one. I also used a 330uF/450V cap in parallel with the first 47uF cap on the board. It is the blue chassis mounted cap in this photo:

http://www.diycustomamps.com/images/...rin7_front.jpg

I was afraid that it would make the amp to stiff sounding, but my friend loves the amp. And the amp is dead quiet which surprised me as most SE amp usually have some hum in them.

tung

[F_BSurfer]

Real nice tung been away for awhile trying to get caught up here have been working on a 18w trem trying to find time to get it done........Not doing scratch build bought chassis, board,& parts from ceriatone pick a some gds transformer up off ebay....I'm just a rookie at this might have some ?'s if you don't mind....

[tunghaichuan***]

Real nice tung been away for awhile trying to get caught up here have been working on a 18w tmb trying to find time to get it done........Not doing scratch build bought chassis, board,& parts from ceriatone pick a some gds transformer up off ebay....I'm just a rookie at this might have some ?'s if you don't mind....

Sure, I'd be happy to help (if I can). You can PM here, or send an email to steve[at]diycustomamps.com

tung

[tunghaichuan***]

Okay, I spent about two hours today finishing up the wiring. I'd been kinda stalled as I was facing wiring the filaments, and I hate wiring filaments. But a little poke from Duhvoodooman got me going again :

Pix here.

I started off by finishing up the filament wiring. It went okay, but it takes a while and is painstaking work. Did I mention I hate wiring filaments?

Next I finished up the power tube socket and preamp tube socket connections. I like these new ceramic sockets, they take solder very well. I got good consistent, clean joints using them. We'll see how well they hold up, I think they are Chinese-made.

Next I wired the input sockets. This amp has the feature of having a single triode input and two triodes in parallel. Kind of like jumpering an old plexi, but the amp is pre-jumpered. One input is the single triode, the other is both in parallel. Two triodes in parallel give a slightly more complex tone due to the differences in the triodes and a little bit more gain.

Then I wired the volume and tone control. The tone control is a lot like the Tweed Princeton control, it is a low loss type that subtracts treble so you get a brighter sound and a less bright sound as you turn the control down. It uses different values for the pot and cap as the 18W is a brighter amp.

Finally, I wired the grounds. I used star grounding in this amp; every grounding node has its own return to the star ground. This is done to prevent ground loops, which introduce noise into the amp. This amp had the most individual grounds I've done: seven total.

This last pic shows the finished wiring.

I'm going to let this sit over night before I give it one finally inspection to make sure all the wiring is correct. Then I'll install the tubes and fire it up. With any luck, it will work the first time and then I can check the bias and basic tone.

Stay tuned.

tung

[duhvoodooman***]

: : OK, now we're talkin'! Looking forward to the report after you flip the switch!