2w Sub Miniature Express

[soma_hero]

Doesn't the resistance of the pot replace the two resistor to ground?

[UR12]

Thanks Griz , I cant wait to get some better clips made.

I was having a PM conversation with Gary on the hum balance setup he has so that I can include those parts in the BOM....

I have to show my ignorance here.... but if you are using the Heyboer trannys with the CT, is a hum balance even needed???

Gary used a 594-63X201 trimmer pot (don't know the value) and 2 660-MOSX3CT631RR15J .1R 3W metal film resistors (both are Mouser part numbers). Normally, an artificial CT uses 100R, so what is it that I am missing here- these seem like really low value R resistors....

Again, my ignorance is showing..

The pot is a 200 ohm pot and it indeed does take the place of the two 100 ohm resistors. The .1 ohm resistors was installed to correct a problem with Gary's Hammond tranny that put out 7 VAC instead of 6.3. The .1's drop just enough voltage to get the 7 volts knocked down to 6.3. unless your tranny is running to much voltage on your heaters they won't be needed. Just the hum pot. I had the custom Heyboers made with a CT on the heater winding so the pot and resistors won't be needed.

My plan is to supply the Kits with all parts needed to build the amp (Less the cab). I won't be selling just the board sets so unless someone wants to build one from scratch with Hammond Trannys all of this should be a non issue if you buy the kit.

Hope that helps clear things up.

The new boards have shipped and will be here in a few days . All the parts are in stock or ordered so every thing should be ready to go by Mar 1st. Just keep checking Hallamplification.com for updates.

Sorry Gary we must have posted at the same time

[gahult]

Gary used a 594-63X201 trimmer pot (don't know the value) and 2 660-MOSX3CT631RR15J .1R 3W metal film resistors (both are Mouser part numbers).

The 594-63X201 trimmer pot is a 200 Ohm.

The 660-MOSX3CT631RR15J are .15 Ohm
660-MOSX3CT631RR10J is .10 Ohm if the .15 drops your filament voltage more than you want.

These are used with the Hammond transformer.

[UR12]

Yet another update. The new boards are in and I am just waiting on a couple more parts and I should have everything ready to go. I was able to source a 500k dual pot that is made by Alpha and it is the right size to fit the board instead of using the smaller 12mm pot and adapting it to fit. I worked through the calulations and with the lower B+ voltage (~170vdc), instead of the 500v spec the larger version is using on the bigger amps, and it will work just fine and is well above the required ratings for a amp with the 170v B+. The bad news is that I had to order it from a Hong Kong supplier and I think they put it on a slow boat from China. It should be here any day. I am also waiting on White Davies knobs to include with the kits. Those are the only two parts I am mising and I will be updating my web page this weekend with prices and shipping information. I will also post a link here in the for sale forum.

We should be doing some better clips this weekend. It seems like evertime I get a chance to get a guitar picker over to record we either get a snow/sleet/ice or monsoon storm. I am praying for better weather this weekend

I did get a few extra faceplates in for the kits and if any of you guys who bought the pre punched chassis want one just PM me for a price.

Here are a few pics of the amp built with all of the parts included in the kit (Wrong knobs of course).

[goldtech]

Hi,

Been searching this thread for soundclips. If there are any please link me.

Thank You!

[UR12]

Hi,

Been searching this thread for soundclips. If there are any please link me.

Thank You!

Page 4. I believe it is the 7th post down. Not the best quality. Thats why I hope to get new ones this weekend.

https://tubeamparchive.com/viewtopic.ph ... c&start=45

[Ron Worley]

Can any of you tell me the correct P/N for the in / out jacks? I ordered a Neutrik mono 1/4 switched jack with 4 pins, but it appears from the photos that Dana used a stereo jack with 6 pins (has 2 pins in the middle that are not on the one I bought).

Also (I may have missed this somewhere), can someone tell me the proper way to install the tubes, i.e. what leads to what pins in the dip sockets??

[grizz]

I like how you've got the OT wired directly into PCB and then it looks like you have the tubes soldered into IC sockets which fit into another socket on the board...I wouldn't have thought of that....Very cool.

Scott

[UR12]

I like how you've got the OT wired directly into PCB and then it looks like you have the tubes soldered into IC sockets which fit into another socket on the board...I wouldn't have thought of that....Very cool.

Scott

Yes, I have heard comments regarding the subminis and some people don't like the idea of not being able to change a tube without getting out a soldering iron and solder sucker. These tubes are very long life and are subjected to some of the toughest military specs in the industry, (like good to 20,000 Gs ). There were sockets for the subminis but they are pretty much extinct and I devised this way to do it using economical and easy to get 8 pin DIP sockets. You can buy extra tubes and solder them onto a socket and have them ready to go at a moments notice if you are so inclined.

Check out this link to the history of the sub miniature tube
http://techtv.mit.edu/tags/760-raytheon ... technology

Can any of you tell me the correct P/N for the in / out jacks? I ordered a Neutrik mono 1/4 switched jack with 4 pins, but it appears from the photos that Dana used a stereo jack with 6 pins (has 2 pins in the middle that are not on the one I bought).

Also (I may have missed this somewhere), can someone tell me the proper way to install the tubes, i.e. what leads to what pins in the dip sockets??

I'll have to look when I get home . At first I had stereo cliff jacks laying around so I decided to make the boards to fit either the stereo or the mono shorting jacks. So to answer your question you can use either one. I ordered a bunch of jacks that stand up off the board about 1/8" for the speaker jacks. Unfortunatly, this was also from a supplier in Hong Kong and I have no idea who makes them or what the part number is. These will be supplied in the kit so that you can use a right angle "Fender Style" speaker plug. The other for the input jack has to sit close to the board for the holes in the chassis and front panel to line up. So there will be two different style jacks used on the Kits and production amps.

I also have a diagram that I have at home showing how to connect the tubes to the board . If you look on the board you will see a rectangle around each tube with a notch on one side. If you align the notch to the left and look down from the top of the board pin one is on the bottom left.

maybe this will make more since.

[davent]

Hello,
These guys have sub-minature tube sockets listed but they do cost an arm and a leg.

http://members.shaw.ca/pacifictv/socket.htm#submin

dave

[grizz]

I thought sub miniatures have wires instead of pins? How would tube sockets work?

[UR12]

I thought sub miniatures have wires instead of pins? How would tube sockets work?

You have to cut the wires off short to about 1/4 " (Kind of like a socket for small transistors) The sub mini sockets are available but hard to find sometimes and expensive compared to the DIP which works just fine. I would also need the PCB mount sockets instead of the solder lug which makes it even harder to find.

[JAKE]

Dana
Don't know if you found a source for the 8-pin dip sockets yet, but have you looked at the NTE423 or the NTE436W8? I think Mouser has that line as well as most electronic suppliers in the replacement biz. Love the project good read.

[UR12]

Dana
Don't know if you found a source for the 8-pin dip sockets yet, but have you looked at the NTE423 or the NTE436W8? I think Mouser has that line as well as most electronic suppliers in the replacement biz. Love the project good read.

Thanks Jake and welcome to the forum!

I am using the machined contact 8 pin DIP Socket from Mouser. Although either will work, they seem to hold the tubes better than the spring type contact. I have used both and even though the machined sockets are a little more expensive I like them better.

[Ron Worley]

I'll have to look when I get home . At first I had stereo cliff jacks laying around so I decided to make the boards to fit either the stereo or the mono shorting jacks. So to answer your question you can use either one. I ordered a bunch of jacks that stand up off the board about 1/8" for the speaker jacks. Unfortunatly, this was also from a supplier in Hong Kong and I have no idea who makes them or what the part number is. These will be supplied in the kit so that you can use a right angle "Fender Style" speaker plug. The other for the input jack has to sit close to the board for the holes in the chassis and front panel to line up. So there will be two different style jacks used on the Kits and production amps.

I also have a diagram that I have at home showing how to connect the tubes to the board . If you look on the board you will see a rectangle around each tube with a notch on one side. If you align the notch to the left and look down from the top of the board pin one is on the bottom left.

maybe this will make more since.

I see the notch on the socket- I guess it would be easier to see where the tube's "notch" (free area between pins 1 and 8 ) goes relative to the DIP socket's notch... If that makes any sense either....

I think that using the stereo jacks makes sense because it provides 6 mounting pins versus 4, giving it probably better mechanical stability and reliability over time...