4-4-0 [2 NEW BUILDS WITH PICS; THE 2 WATT WRECK]

[GainMaster]

Ok, I got around to draw the rest in.
Not everything is drawn in a 100% correct (few missing wires in out jacks wiring), but the idea should be pretty clear.

I've made to versions, with the two different OT placements.
In the first, the OT secondaries are a bit parallel to the heater wires.
In the second, the OT is a bit closer than 2" to the PI....
Don't know which is the best, so I need an advice there...

The heater wires are going parallel to the 220V lines at the right edge of the chassis, but I plan on running the 220V lines at the bottom (open end) of the chassis, and the heaters on the top, so they'll be about 5cm apart (about 2 inches I think). Is this enough distance between them?

Lemme know what you think, and if you see anything that'll cause problems.

Change the 150k attenuation resistor between the second and third stage to 100k. Cliff and I both ended up with 100k there.

Don't run the heater wires to and from the back of the chassis. Just run them close to the tubes. No reason to have all that extra wire.

No need for 4 diodes for rectification unless you are going to bigger power later. 2 are fine. The diodes for rectification are backwards.

Several terminals need to be moved away from the ground buss.

Where are those red wires going to between the rectifier diodes? They don't terminate anywhere.

Why is the standby hooked to the + on a supply cap? Shouldn't it be grounded instead?

Neat way to redraw Cliff's circuit to raise the floor of the bias supply.

That is all I see for now.

Brian

[Edited for errors, mine not yours ]

[arjepsen]

Change the 150k attenuation resistor between the second and third stage to 100k. Cliff and I both ended up with 100k there.
Don't run the heater wires to and from the back of the chassis. Just run them close to the tubes. No reason to have all that extra wire.

done

No need for 4 diodes for rectification unless you are going to bigger power later. 2 are fine. The diodes for rectification are backwards.
Where are those red wires going to between the rectifier diodes? They don't terminate anywhere.

The two red wires are coming from the PT. Admittedly this could be a bit hard to see, so I've darkened the hole for the PT a bit. Both primary and secondary PT wires are going to this hole.
I'm using a toroidal PT that doesn't have any CT's, so I'm using the 4 diodes to make a bridge rectifier. Have I put it together wrong?

Several terminals need to be moved away from the ground buss.

I presume you mean up above the PA part of the board?
I've moved it in the updated layout. Is this what you mean?

Why is the standby hooked to the + on a supply cap? Shouldn't it be grounded instead?

Uhm... I thought the standby switch is usually between B+ and B+1.
It seems to be like that in the schematic. Isn't that usually how it's done??

Neat way to redraw Cliff's circuit to raise the floor of the bias supply.

I just realized I'd forgotten the wire from pin 4 of the PI to the 47k+10uF <-> 180k junction.
Since the PT doesn't have any CT's I put the two 100R resistors in there instead. But checking out on Valvewizard.co.uk it seems I should connect this wire to the mentioned junction instead of ground.
I can avoid the wire to the PI by doing it this way, right?
Or am I just messing up the best way to put things together?

I have to admit it can be a bit hard to see how the bias circuit is laid out. I've moved it around a bit, so it's a bit easier to see how things are connected. Zooming in, in the pdf, might also make it a bit easier to see it clearer.

Thanks a lot for the help so far.
Here's the updated layout. Lemme know if there's anything else bad.

[mss1]

Didnt Fernandes guitars market something like this called the Sustainiac or Sustainior? They had a line of guitars with a transducer built in to the guitar itself...

Cool! I was quite impressed with the clean Sustainiac sound in this "Open Mind" song: http://www.sustainiac.com/glenn_delaune.mp3

Check it out...

Mss1

[arjepsen]

Any comments on my questions?
Or on the last layout I posted above?

[GainMaster]

Any comments on my questions?
Or on the last layout I posted above?

Sorry I didn't get back sooner. I have a big project at work requiering a lot of overtime. I'll take a look this weekend.

Thanks
Brian

[GainMaster]

Any comments on my questions?
Or on the last layout I posted above?

Great layout drawing so far. I have no idea how to do this myself. Looked it over and here is what I see.

Need to finish hooking up the output jacks.

The impedance switch would present better layed on its side as you have 5 wires comming off the OT going to it and two comming off it. If you need the color codes I can post them.

Finish connecting the .68u presence cap to pins 2 and 3 of the pot. I couldn't see the connections.

I still don't understand the extra two diodes connected to the junction of C6 C7 and C8. Does this simulate a ground?

I would move the OT a little to the left and move the bias pots out from under the turret board. A bad solder joint or something there would be very difficult to troubleshoot.

Anyway, great work and sorry I didn't get back sooner. When are you starting the build?

Brian

[arjepsen]

Thankyou soooo much for your help so far. I really appreciate that you take the time, even though you're busy.
I pretty much have everything, but I want to be certain about the layout, before I start drilling

I'm doing the layout in openoffice-draw.
This time, I'll post the draw-file itself, so you can mess around with it if you want. It's very nice to play around with a layout in.

In the updated layout, I've hooked up the out-jacks, and impedance switch. (the coloring might not be exactly right, since I haven't figured out how to make white wires yet).
I don't actually have the impedance swithc yet. For starters, I'm just gonna hook it up for an 8 ohm speaker. And then install the switch later. But the wires should show how I'd lay it out.

The .68uF was connected, but I had made the wires grey, wich could be very hard to see. They're black now.
Actually, I just printed it out (in black/white), and I can see, that some stuff doesn't really show up very well. Make sure to check the pdf-file. There you should be able to see everything.

About the diodes, again, the PT does not have a Center Tap.
So I tried to make a bridge rectifier like described here:
http://www.freewebs.com/valvewizard/bridge.html
The extra two diodes goes to ground. (the closest ground "star" is the junction you mentioned).
Hope this clarifies what I'm trying to do.
Any problems with it?

Also, in the schematic, the heaters are referenced to the C6-R6 junction.
For a PT without a CT for the heaters, the website mentioned above suggests two 100R resistors going to ground from the heaters.
I've tried to implement that, but I wonder which way is better. The way described in the schematic, or the way described on valvewizard?

I'm a little worried about moving the OT left, since it is already very close to the Powertube, and moving it left would bring it closer to the PI.
Also, I wonder if there would be problems with moving the bias-pots too close to the 220V wires/jack.
I've attached a few pics to show how close these things are to each other.
Check 'em out, and let me know what you think.

[arjepsen]

Thankyou soooo much for your help so far. I really appreciate that you take the time, even though you're busy.
I pretty much have everything, but I want to be certain about the layout, before I start drilling

I'm doing the layout in openoffice-draw.
This time, I'll post the draw-file itself, so you can mess around with it if you want. It's very nice to play around with a layout in.

In the updated layout, I've hooked up the out-jacks, and impedance switch. (the coloring might not be exactly right, since I haven't figured out how to make white wires yet).
I don't actually have the impedance swithc yet. For starters, I'm just gonna hook it up for an 8 ohm speaker. And then install the switch later. But the wires should show how I'd lay it out.

The .68uF was connected, but I had made the wires grey, wich could be very hard to see. They're black now.
Actually, I just printed it out (in black/white), and I can see, that some stuff doesn't really show up very well. Make sure to check the pdf-file. There you should be able to see everything.

About the diodes, again, the PT does not have a Center Tap.
So I tried to make a bridge rectifier like described here:
http://www.freewebs.com/valvewizard/bridge.html
The extra two diodes goes to ground. (the closest ground "star" is the junction you mentioned).
Hope this clarifies what I'm trying to do.
Any problems with it?

Also, in the schematic, the heaters are referenced to the C6-R6 junction.
For a PT without a CT for the heaters, the website mentioned above suggests two 100R resistors going to ground from the heaters.
I've tried to implement that, but I wonder which way is better. The way described in the schematic, or the way described on valvewizard?

I'm a little worried about moving the OT left, since it is already very close to the Powertube, and moving it left would bring it closer to the PI.
Also, I wonder if there would be problems with moving the bias-pots too close to the 220V wires/jack.
I've attached a few pics to show how close these things are to each other.
Check 'em out, and let me know what you think.

[GainMaster]

Thankyou soooo much for your help so far. I really appreciate that you take the time, even though you're busy.
I pretty much have everything, but I want to be certain about the layout, before I start drilling

I'm doing the layout in openoffice-draw.
This time, I'll post the draw-file itself, so you can mess around with it if you want. It's very nice to play around with a layout in.

In the updated layout, I've hooked up the out-jacks, and impedance switch. (the coloring might not be exactly right, since I haven't figured out how to make white wires yet).
I don't actually have the impedance swithc yet. For starters, I'm just gonna hook it up for an 8 ohm speaker. And then install the switch later. But the wires should show how I'd lay it out.

The .68uF was connected, but I had made the wires grey, wich could be very hard to see. They're black now.
Actually, I just printed it out (in black/white), and I can see, that some stuff doesn't really show up very well. Make sure to check the pdf-file. There you should be able to see everything.

About the diodes, again, the PT does not have a Center Tap.
So I tried to make a bridge rectifier like described here:
http://www.freewebs.com/valvewizard/bridge.html
The extra two diodes goes to ground. (the closest ground "star" is the junction you mentioned).
Hope this clarifies what I'm trying to do.
Any problems with it?


Man, that is one wicked looking PT. I see what you are up against now. Too bad you can't just pick up a 369JX, much smaller. Since I'm not an enginer type, I really can't say if you will have problems with the extra diodes.

Also, in the schematic, the heaters are referenced to the C6-R6 junction.
For a PT without a CT for the heaters, the website mentioned above suggests two 100R resistors going to ground from the heaters.
I've tried to implement that, but I wonder which way is better. The way described in the schematic, or the way described on valvewizard?

The 100rs aren't needed. The AX84 guys did that for a number of years but have found them unnecessary. Cliff's method raises the 6v floor for the heaters quite nicely.

I'm a little worried about moving the OT left, since it is already very close to the Powertube, and moving it left would bring it closer to the PI.
Also, I wonder if there would be problems with moving the bias-pots too close to the 220V wires/jack.

I would keep things as you have them then if you are going to stick with that PT.

I've attached a few pics to show how close these things are to each other.
Check 'em out, and let me know what you think.

[GainMaster]

Thankyou soooo much for your help so far. I really appreciate that you take the time, even though you're busy.
I pretty much have everything, but I want to be certain about the layout, before I start drilling

I'm doing the layout in openoffice-draw.
This time, I'll post the draw-file itself, so you can mess around with it if you want. It's very nice to play around with a layout in.

In the updated layout, I've hooked up the out-jacks, and impedance switch. (the coloring might not be exactly right, since I haven't figured out how to make white wires yet).
I don't actually have the impedance swithc yet. For starters, I'm just gonna hook it up for an 8 ohm speaker. And then install the switch later. But the wires should show how I'd lay it out.

The .68uF was connected, but I had made the wires grey, wich could be very hard to see. They're black now.
Actually, I just printed it out (in black/white), and I can see, that some stuff doesn't really show up very well. Make sure to check the pdf-file. There you should be able to see everything.

About the diodes, again, the PT does not have a Center Tap.
So I tried to make a bridge rectifier like described here:
http://www.freewebs.com/valvewizard/bridge.html
The extra two diodes goes to ground. (the closest ground "star" is the junction you mentioned).
Hope this clarifies what I'm trying to do.
Any problems with it?

I can't say as I am not an engineer type.

Also, in the schematic, the heaters are referenced to the C6-R6 junction.
For a PT without a CT for the heaters, the website mentioned above suggests two 100R resistors going to ground from the heaters.
I've tried to implement that, but I wonder which way is better. The way described in the schematic, or the way described on valvewizard?

The 100rs are not needed. The guys at AX84 did that for a number of years but have learned they are unnecessary. Cliff's way raises the 6v floor much higher and protects the preamp tubes better.

I'm a little worried about moving the OT left, since it is already very close to the Powertube, and moving it left would bring it closer to the PI.
Also, I wonder if there would be problems with moving the bias-pots too close to the 220V wires/jack.

If you are goint to stick with that PT I would leave it alone. Man that's one big bugger. Hammond makes a 369JX that would work.

I've attached a few pics to show how close these things are to each other.
Check 'em out, and let me know what you think.

Thanks
Brian

[arjepsen]

Ok, one last question though
Ditching the two 100R's, I'm looking at the schematic, and see that the heaters are referenced to the C6-R6 junction from the PI.
Is there any particular reason for tapping it from PI tube?
Layout wise, it would be much easier to just tap it to one of the connections the the 100R's had.

[Colossal]

I've been following this thread with great interest. Nice work Cliff and Gainmaster.

<b>arjepsen</b>: Your layout is looking very nice. I noticed however that you have the 82k/100k (R22 & R23) plate resistors on the PI labeled as 82k/82k, so one of them should be changed to 100k.

<b>Cliff/Gainmaster</b>: The negative feedback resistor on the 4-4-0 schematic is labeled as 5k6. Should this be 56k? If so, then arjepsen's layout also shows 5k6 and should be corrected. *edit* I also noticed that B+1 on the 4-4-0 PS drawing does not lead anywhere. B+2 is going to the OT instead of B+1. Or is this a temporary thing using B+2 to get the plate voltage down to around 340V on the 6SN7?

[GainMaster]

I've been following this thread with great interest. Nice work Cliff and Gainmaster.

<b>arjepsen</b>: Your layout is looking very nice. I noticed however that you have the 82k/100k (R22 & R23) plate resistors on the PI labeled as 82k/82k, so one of them should be changed to 100k.

<b>Cliff/Gainmaster</b>: The negative feedback resistor on the 4-4-0 schematic is labeled as 5k6. Should this be 56k? If so, then arjepsen's layout also shows 5k6 and should be corrected.

Thanks for the encouragement.

The schematic shows 5K6. Personally, I like it higher than that as I put a NFB pot on mine. Anything from 5K6 to 25k works fine.

Brian

[Colossal]

The schematic shows 5K6. Personally, I like it higher than that as I put a NFB pot on mine. Anything from 5K6 to 25k works fine.

Brian

Ok thanks for clarifying that! So that is actually meant to be 5k6. Sorry, didn't know if that was a typo or the legit value!

One other question: You mentioned before that you felt that the 6SN7 did a better job of "big amp feel". Do you feel that if you were using the 2W at full throttle, it could keep up with a drummer in a small room and in a practice environment (not live). I'm wondering about the viability of the Wreckless as a good tool for this...I would be using a 2x12 with Greenbacks. For comparison, I'm using a 6V6 Plexi dimed but with a VVR at about 40% power. This seems to be the sweet spot for tone and volume with that amp and is enough to keep up with a drummer at a comfortable level. Just trying to get a feel for what 2w cranked feels like

[UR12]

The schematic shows 5K6. Personally, I like it higher than that as I put a NFB pot on mine. Anything from 5K6 to 25k works fine.

Brian

Ok thanks for clarifying that! So that is actually meant to be 5k6. Sorry, didn't know if that was a typo or the legit value!

One other question: You mentioned before that you felt that the 6SN7 did a better job of "big amp feel". Do you feel that if you were using the 2W at full throttle, it could keep up with a drummer in a small room and in a practice environment (not live). I'm wondering about the viability of the Wreckless as a good tool for this...I would be using a 2x12 with Greenbacks. For comparison, I'm using a 6V6 Plexi dimed but with a VVR at about 40% power. This seems to be the sweet spot for tone and volume with that amp and is enough to keep up with a drummer at a comfortable level. Just trying to get a feel for what 2w cranked feels like

Just as a rule of thumb the Plexi should be putting out about 20w and a 2w amp will sound 1/2 as loud as a 20 watt amp. At 40% reduction in B+ voltage doesn't corelate to a 40% reduction in power, but if it did you would still be playing with an amp that was putting out about 8 - 10 watts. When you start playing with amps that are below 5 watts the choice speaker's efficency can make a huge difference in total loudness.