I didn't include the resistors on the board as my original plan was to have heyboer make a PT for this thing with a CT so the resistors wouldn't be needed.
Just a heads up!!!!
2w Sub Miniature Express
Moderators: pompeiisneaks, Colossal
Re: 2w Sub Miniature Express
John just PM'd me with a hum problem and I thought I would pass this on to the rest of you guys building these. The Hammond PT doesn't have a CT for the Heater winding and you will have to add a couple of 100 ohm 1/2 w resistors on the bottom of the board from where each heater wire from the tranny solders to the board to a ground spot close by on the ground plane on the bottom of the board. I will post some pics when I get home this evening.
I didn't include the resistors on the board as my original plan was to have heyboer make a PT for this thing with a CT so the resistors wouldn't be needed.
Just a heads up!!!!
I didn't include the resistors on the board as my original plan was to have heyboer make a PT for this thing with a CT so the resistors wouldn't be needed.
Just a heads up!!!!
Re: 2w Sub Miniature Express
Well, it's done.... kinda...
Very, very neat. And it'll surprise you with it's volume. Parts came in fits & starts & that held up the project. Most amount of effort... cutting out the chassis, aside from that you could build this amp in a long afternoon. I came up with a quick way to get the tubes in the DIP sockets, bend the leads out 90 degrees to the tube right at the base, hold the tube down on the edge of a piece of aluminum cut to .284 thick and bend the leads back parallel to the tube & cut this leg to 1/8". That'll push right in the DIP socket. Artificial CT a must, took care of 85% of the hum... thanks Dana! I've got 1/4 watt resistors in it right now, that's all I had, 1/2 watt 100 ohm will get ordered.
Heat sink for the VVR FET is in the works. BTW that's a NTE2946 (Mouser # 526-NTE2946) if you haven't already called Dana about it. I'm working on a bias setting now, with help of course. Can't wait to build the "production" version.
Thanks again Dana!
John
Very, very neat. And it'll surprise you with it's volume. Parts came in fits & starts & that held up the project. Most amount of effort... cutting out the chassis, aside from that you could build this amp in a long afternoon. I came up with a quick way to get the tubes in the DIP sockets, bend the leads out 90 degrees to the tube right at the base, hold the tube down on the edge of a piece of aluminum cut to .284 thick and bend the leads back parallel to the tube & cut this leg to 1/8". That'll push right in the DIP socket. Artificial CT a must, took care of 85% of the hum... thanks Dana! I've got 1/4 watt resistors in it right now, that's all I had, 1/2 watt 100 ohm will get ordered.
Heat sink for the VVR FET is in the works. BTW that's a NTE2946 (Mouser # 526-NTE2946) if you haven't already called Dana about it. I'm working on a bias setting now, with help of course. Can't wait to build the "production" version.
Thanks again Dana!
John
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Re: 2w Sub Miniature Express
Nice! 
I hope to get in on the next batch.
I hope to get in on the next batch.
Tom
Don't let that smoke out!
Don't let that smoke out!
Re: 2w Sub Miniature Express
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Last edited by UR12 on Wed Jan 07, 2009 3:23 am, edited 1 time in total.
Re: 2w Sub Miniature Express
John
That looks awesome! The two I have here are pretty quiet as far as hum is concerned. I wonder if you install a hum balance control like they use on the Fender amps if you could dial it all the way out. That would require a 200 ohm 1/2 watt trim pot with the wiper going to ground and each outer lug going to one side of the heater winding.
It is louder than you would think and that was my first impression also. I checked my bias and I am at -32v at pin 1 of each 5902. (You are very close at -35) I set mine using a scope but I bet we can use a couple of those 8 pin dip sockets and make a miniature version of a bias probe.
That looks awesome! The two I have here are pretty quiet as far as hum is concerned. I wonder if you install a hum balance control like they use on the Fender amps if you could dial it all the way out. That would require a 200 ohm 1/2 watt trim pot with the wiper going to ground and each outer lug going to one side of the heater winding.
It is louder than you would think and that was my first impression also. I checked my bias and I am at -32v at pin 1 of each 5902. (You are very close at -35) I set mine using a scope but I bet we can use a couple of those 8 pin dip sockets and make a miniature version of a bias probe.
Re: 2w Sub Miniature Express
Thanks Dana, this is a really cool amp. I love it. Played it for a couple of hours last night, it's a mean little mutha!
The odd thing, at least to me, is that the remaining hum is worse between 1/2 & 3/4-7/8 volume, cranked it drops. It's actually acceptable, but as I said not quite as quiet as my LP clone.
I'll try the hum balance pot.
Gary, I haven't got a heat-sink on the FET yet, I've got one drawn up but we're too busy to make it.
My heaters are running at 6.9 volts, isn't that a little stout?
The odd thing, at least to me, is that the remaining hum is worse between 1/2 & 3/4-7/8 volume, cranked it drops. It's actually acceptable, but as I said not quite as quiet as my LP clone.
I'll try the hum balance pot.
Gary, I haven't got a heat-sink on the FET yet, I've got one drawn up but we're too busy to make it.
My heaters are running at 6.9 volts, isn't that a little stout?
Re: 2w Sub Miniature Express
No guaranty that this is perfect, measure your parts & confirm that the hole diameters match your components. Some holes may need file work to get the board to slide in. I've moved the board forward from my installation so spacers behind the pots should not be required. Dana suggested not soldering the pots to the board before everything was mounted in the chassis and adjusted to fit, I think that's a good idea. I mounted my output jack in the chassis, that hole is not shown. I enlarged the main opening as well so all the extra cut-outs should not be required. There should be 4 drawing sheets in the pdf.
John
John
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Re: 2w Sub Miniature Express
John,
Great work.
Regarding the filament voltage. Not sure if anyone has seen the spec sheet on the 5902's but its 6.3 +/- 5% so I think it is a little "stout".
Might be worth looking at inline resistors to drop the filaments down a little.
Great work.
Regarding the filament voltage. Not sure if anyone has seen the spec sheet on the 5902's but its 6.3 +/- 5% so I think it is a little "stout".
Might be worth looking at inline resistors to drop the filaments down a little.
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Re: 2w Sub Miniature Express
John
I echo Fishy's sentiments exactly, Great work on the chassis layout and the amp!
I am building another one of these from the ground up and photographing all the steps to build the amp. When I get it finished I should be able to put together a build manual. I have the schematic almost finished along with just a few more parts to look up on the BOM and it will be complete. Jeanne from BnP lasers shipped out a couple of front panels yesterday and I should have those today or tomorrow. I built a small head cab for the amp last weekend that measured 13.5" Wide x 6" Tall and 7 inches deep. I did it in red tolex for the top, bottom and sides and the valence over the front panel is in black tolex with silver piping. Black metal corners and handle finished it off. ( I'll post a pic as soon as the front panels arrive) The front panels I have coming in are satin black (semi gloss) with white letters. I am going with white knobs for now but may change those to red later on.
Basically, I am trying to get a lot of stuff ready for the Columbus, OH guitar show this weekend. I will have the Lil Devil at the show and if anyone from the forum is going to be there, please stop by and say hello and give it a test run. I will also have the 6V6 Express combo and a few other amps there along with VVRs and channel switching kits.
I have rescheduled my appointment with the CNC guy for next Monday and hopefully I will be able to offer a pre punched chassis with the future kits. Considering that this amp was just an idea 4 months ago it has come a long way in a short period of time and I really appreciate everyones input and help.
I echo Fishy's sentiments exactly, Great work on the chassis layout and the amp!
I am building another one of these from the ground up and photographing all the steps to build the amp. When I get it finished I should be able to put together a build manual. I have the schematic almost finished along with just a few more parts to look up on the BOM and it will be complete. Jeanne from BnP lasers shipped out a couple of front panels yesterday and I should have those today or tomorrow. I built a small head cab for the amp last weekend that measured 13.5" Wide x 6" Tall and 7 inches deep. I did it in red tolex for the top, bottom and sides and the valence over the front panel is in black tolex with silver piping. Black metal corners and handle finished it off. ( I'll post a pic as soon as the front panels arrive) The front panels I have coming in are satin black (semi gloss) with white letters. I am going with white knobs for now but may change those to red later on.
Basically, I am trying to get a lot of stuff ready for the Columbus, OH guitar show this weekend. I will have the Lil Devil at the show and if anyone from the forum is going to be there, please stop by and say hello and give it a test run. I will also have the 6V6 Express combo and a few other amps there along with VVRs and channel switching kits.
I have rescheduled my appointment with the CNC guy for next Monday and hopefully I will be able to offer a pre punched chassis with the future kits. Considering that this amp was just an idea 4 months ago it has come a long way in a short period of time and I really appreciate everyones input and help.
Re: 2w Sub Miniature Express
Good luck at the show!
Re: 2w Sub Miniature Express
This is where I am fer now.
[IMG:640:480]http://i405.photobucket.com/albums/pp13 ... C01618.jpg[/img]
[IMG:640:480]http://i405.photobucket.com/albums/pp13 ... C01619.jpg[/img]
[IMG:640:480]http://i405.photobucket.com/albums/pp13 ... C01620.jpg[/img]
[IMG:640:480]http://i405.photobucket.com/albums/pp13 ... C01621.jpg[/img]
Thanks for the help Dana and John and whom ever my drugs and alzheimers is making me forget to thank.
And damned if the bench ain't dirty.
Gary
[IMG:640:480]http://i405.photobucket.com/albums/pp13 ... C01618.jpg[/img]
[IMG:640:480]http://i405.photobucket.com/albums/pp13 ... C01619.jpg[/img]
[IMG:640:480]http://i405.photobucket.com/albums/pp13 ... C01620.jpg[/img]
[IMG:640:480]http://i405.photobucket.com/albums/pp13 ... C01621.jpg[/img]
Thanks for the help Dana and John and whom ever my drugs and alzheimers is making me forget to thank.
And damned if the bench ain't dirty.
Gary
In the 60's people took acid to make the world weird. Now the world is weird , and they take Prozac to make it normal.
Re: 2w Sub Miniature Express
Gary
That is looking great!! Did you install the input jack on top of the board instead of the bottom of the board for any particular reason?
That is looking great!! Did you install the input jack on top of the board instead of the bottom of the board for any particular reason?
Re: 2w Sub Miniature Express
Ah, Sh*t
Duh
Got me again.
Pooper. Damn drugs.
Gary
Duh
Got me again.
Pooper. Damn drugs.
Gary
In the 60's people took acid to make the world weird. Now the world is weird , and they take Prozac to make it normal.
Re: 2w Sub Miniature Express
Gary,gahult wrote: ... Damn drugs...
As your consulting physician, I must recommend that you not work on this amp. You're in no shape to do that at this time.
Send it all to me and continue your recuperation unimpeded
Tim
In case the NSA is listening, KMA!
In case the NSA is listening, KMA!
Re: 2w Sub Miniature Express
HA HA doc 
Any thing to keep the designer happy.
[IMG:640:480]http://i405.photobucket.com/albums/pp13 ... C01622.jpg[/img]
Sure as hell ain't gonna plug it into the wall for a while.
Gary
Any thing to keep the designer happy.
[IMG:640:480]http://i405.photobucket.com/albums/pp13 ... C01622.jpg[/img]
Sure as hell ain't gonna plug it into the wall for a while.
Gary
In the 60's people took acid to make the world weird. Now the world is weird , and they take Prozac to make it normal.