Dougs Stout beginnings

[lego4040]

So Id like to build my 3rd amp from this site and Its going to be Dougs Stout with the black board. I want to use my 5F2 chassis in my 12" combo cab. If I loose the tube rectifier I have the spot for the second EL84. I have three pots which will allow me to use the gain pot mod(which says master on this chassis. I have the DPDT bright switch which I can use for the gain switch mod or maybe some cap mod. This chassis is larger then Dougs will be and offer me some room. I already have the Allen TP25 PT in it and the small choke, I will need a new OT tho, the Allen OT11c will not work if Im correct. Here are some shots of what I have to work with and chassis I will gut for the most part

[lego4040]

Here is the circuit for this amp

[Willabe]

That cab is beautiful!!!!!

Did you make? What kind of wood is it?


             Brad        

[lego4040]

Believe it or not that's Poplar. John Lyons who is a master and a gentleman owns http://basicaudio.net. He makes wicked pedals from the ground up and he made my cab. I don't know if he still does since the last time I asked he was just to busy. When he picked this wood he explained that poplar is greenish but when left in the sun for long times it turns redish. So go get cheap priced poplar and let it tan in the sun for some amazing results

[tubenit]

That cab is beautiful!  It looks great!

If that is poplar, it sure looks different then the poplar in my area of North Carolina.  I've cut down some 90+ ft tall poplars out of my back yard.  The wood is very green and/or yellowish looking.

With respect, Tubenit

[lego4040]

Tubenit that's is exactly where John is from and the color it was when he got it. He let it suntan for probably two weeks or so

[lego4040]

So my first quest in using this chassis over is removing the tube rectifier and using it for the second EL84. I was thinking about going to solid state(?) and bolting the rectifier to side off chassis where that giant 25 watt power resistor is. The chassis can serve as a heatsink for the rectifier & its out of the way(Now I don't know if thats a good idea or not but I'm just thinking aloud).  Since I'm not using the 5v heater taps for tube heaters that will take some load off of PT. I just need to know If I need to change anything, add a cap or resistor for noise, etc. I was reading some of Merlin's work on that and looked in the library here but I couldn't find anything on changing tube to solid state.

[sluckey]

Have you considered just selling the 5F2 chassis on eBay and starting with a clean slate?

[lego4040]

Yes but shes my baby, first amp I built. The stout board will fit right in and once I pull chassis out I can really measure things out. I dont have a problem with not using the 5Y3 but I want to make sure I can do that and what I might need to do to it. Isnt that what you did with the Revibe

[lego4040]

I would just put the B+ from solid state to the choke

[lego4040]

Hmmm, ordering parts from Site now but the only .68uf cap here is 250V. BOM calls for a 400-600V. You have any laying around Doug that might not be on site   that I can buy from ya

[lego4040]

I see the other BOM has it at 250v, nevermind

[sluckey]

That's a cathode bypass cap in the preamp. Probably never gonna see more than two volts.

[lego4040]

 :thumbsup:thanks Steve, seems I've lost track of time nothing like hanging with the deep Europeans from The Czech Republic  and proving that New Yorkers aren't all DB'S

[Ed_Chambley]

Just not fond of the 5F2?  Sometimes just something different.

That is a great starting point with the 12" cab.  Looks like it is easy to handle.  I am going to try that with poplar.  I just laid out a 1 x 4.

[Ed_Chambley]

Here is the circuit for this amp

Image is too small, can't see the schematic.  Is is a 5F2 with a added master?

[lego4040]

Ed it has the added Master and a extra 12ax7 for some umph. This chassis has every thing if need once I rip out that board. I'll convert to a solid state and use that rectifier hole for second EL84. The bright switch will become either the switch for gain stage. The master volume will become the gain pot mod. I already got my shopping cart loaded here, just need some extra cash

[lego4040]

I ordered all my parts today. I got most parts coming from here but I did wind up going with the Classictone OT for this build. I had to hold off on ordering for a little since my wife got laid off last month, thankfully she just went back to work on Monday.

[lego4040]

Ok, I got my chassis gutted to were I need it today. Parts on the way and I'm ready to Rock. So I want to use my matched pair of 6V6's for this project, two reasons, I ave the sockets in chassis to begin with and my wife just got back to work so I gotta watch the $$. I see the grid resistors for the EL84's are 8.2k and the resistors to ground are 470k. On two 6v6 builds I looked at, like these two are less. Im no expert so I gotta ask what I should do. The trainwreck versions here are 5.6k on grid and 220k to bias and the other version has 1.5k on grid and 220k again to bias which would be ground for this build. 

[lego4040]

Done some research and I will build amp with Doug's specs and just change tubes to 6v6's(of coarse w correct pin outs

[lego4040]

  Doug's board and parts came today and now I have something to keep me occupied. I wired the heaters and lamp today, I also tidied up the PT wires. I also realized after I wired up the 8 pins for the 6v6's I had not just one set of matched EL84's but two sets from JJ   I have the 9 pin sockets for them but if I want to change them I need those socket adapters ASAP. If I can find some decent metal stock I'll shape two out and change sockets before I go further. I did some reading on 6v6 vs EL84's, the best way for me to describe what I read is what we all know already. Cranked American Blues amps vs Cranked British Rock n Roll
Till tomorrow

[EL34]

Looks like you are on your way

[lego4040]

I'm aiming to get the board populated today and maybe put into chassis. In the chassis pic there I put foil tape and heat shrink around heater wires. They pass over output jacks and I wanted to try and keep noise out. I did get radio stations with the circuit that was in here from time to time and now understand why grid res are used. I'm still using the 6v6's although I did find two matched pairs of JJ 84's. Maybe next build will be all four I read an article yesterday on how some amp builders use both the 6v6 pair and EL84 ish pair set up so they can get both the Fender low and fatness along with the British attack.  has or can you use one EL84 and one 6v6????? I'd be the test pig and do it on this build

[MakerDP]

Believe it or not that's Poplar. John Lyons who is a master and a gentleman owns http://basicaudio.net. He makes wicked pedals from the ground up and he made my cab. I don't know if he still does since the last time I asked he was just to busy. When he picked this wood he explained that poplar is greenish but when left in the sun for long times it turns redish. So go get cheap priced poplar and let it tan in the sun for some amazing results

I recently finished a closed-back 1x12 speaker cab that I made out of poplar... the stuff you can buy at Home Depot or Lowe's. I stained it "gunstock" and it turned out beautiful as well. The banding effect from the different edge-joined planks adds an interesting dimension to it. I found the poplar cheap and easy to work and most importantly the cabinet sounds great! I'm going to build a head cabinet for my new 18-watt build to match it this week, hopefully starting tomorrow.

I didn't know about the "suntan trick" I'll have to try that on my next build.

[lego4040]

I need to get some poplar, I've been putting my wood tools together too. Here's my stout as of tonight
 And I've made the cap look vintage. I peeled plastic off, rolled brown paper and schellac.

[MakerDP]

Ok, I got my chassis gutted to were I need it today. Parts on the way and I'm ready to Rock. So I want to use my matched pair of 6V6's for this project, two reasons, I ave the sockets in chassis to begin with and my wife just got back to work so I gotta watch the $$. I see the grid resistors for the EL84's are 8.2k and the resistors to ground are 470k. On two 6v6 builds I looked at, like these two are less. Im no expert so I gotta ask what I should do. The trainwreck versions here are 5.6k on grid and 220k to bias and the other version has 1.5k on grid and 220k again to bias which would be ground for this build. 

I did a 6V6 build a few months ago and used 100k to bias and 5k6 grids. It's basically a Fender Deluxe clone.

[lego4040]

If a 350-0-350 is to high could I drop it by changing the 130ohm 10 watt to say 330ohm 25watt. This was in my amp that was using this PT. Here is power resistor and the board in chassis so I can look at where main cap will go. Looks like main cap is going on top outside chassis

[sluckey]

If a 350-0-350 is to high could I drop it by changing the 130ohm 10 watt to say 330ohm 25watt.

No. That 130Ω resistor is the cathode resistor for the EL84s. If you will be using 6V6s that will need to be 250Ω or higher. That resistor is not used to drop B+. It is used to bias the output tubes.

That 350-0-350 PT will put out 495vdc unloaded. Since you will be using a SS rectifier you can expect that to be pretty high even when loaded. How high? Can't say. That depends a lot on the internal resistance of your PT. You would normally put a dropping resistor between the rectifier and first filter cap to drop B+. My preferred method to drop B+ is to use the correct PT to begin with.

Give us all the info on that PT. Is it an Allen? If so, which one? Was it used in your 5F2? If so, what was the loaded B+ in that amp?

Edit... I see from your original post that you have the Allen TP25 PT. According to Allen's website, the TP25 is rated for 310-0-310 @ 150mA. That PT will be fine for a cathode biased 6V6 PP amp. Still need to use a 250Ω 10W cathode resistor rather than 130Ω 10W.

So, where did this 350-0-350 come from?

[lego4040]

It's the Allen TP25: Upgrade Power Transformer for BF/SF Champ™, VibroChamp™, Bronco™, and Princeton™. 310V-0-310V @ 150ma, 6.3V at 4.5A, 5V at 2A. 50V bias tap, center-tapped heater winding and internal hum shield brought out to a lead for grounding. 2" by 2-1/2" mounting centers, 5.1lbs. Unit is approximately 1" taller than a stock transformer. Supports the use of both 6L6 and EL34 power tubes (with proper socket wiring). Now featuring M-6 grain oriented lamination steel for cooler operation. I got 350-0-350 when I plugged in the tranny not hooked up to anything by chassis. So I will need to step up that bias to 250ohm. I new it was for Biasing but wondered if that would work

[lego4040]

The schem I have for the Allen amp I built doesn't give any voltage readings either.

[sluckey]

The schem I have for the Allen amp I built doesn't give any voltage readings either.

And you didn't record any voltage readings when you built it, right? Or just before you scrapped it for the stout build either?

[lego4040]

I didn't take any readings back then, first amp I ever built and wasn't poking around in there. I was going to before I took it apart but was to anxious to start new project

[sluckey]

I think you'll be OK with that PT. Looks like you have a STBY switch? If you need to drop B+ some maybe you could do my 'Standby Plus' mod like on the AC15. Otherwise, reserve a place to put a big dropping resistor just in case.

[lego4040]

Will do and look for your drop down link

[lego4040]

Found it, what about the Zener diode trick off the center tap to ground for a few volt dropage

[sluckey]

That'll work too, although it's not my preferred method. Just put all the voltage dropping options on the back burner until you build the amp. You may not need them at all.

[lego4040]

OT came today I waited outside for the mailman to come so I wouldn't miss him
Also some more parts from Doug coming soon

[lego4040]

So I got some work done and once my last of parts come in I can finish up. The OT is in the holes that was in chassis(factory) but it's same way as PT, will I have issues?  Not sure were cap is gonna go, I can squeeze it between chassis and PT underneath and actually fit cap next to it. It will keep wires short as possible too. Now I have the DPDT switch doing nothing maybe some cap mod possible? I am adding the gain pot also

[EL34]

Holy smokes, what kind of power tranny is that and why is it 3 times taller than a normal PT?

[lego4040]

That's the AllenAmp PT and I believe Heyboer is making all their trannies. It's a beast isn't it. It's what came with the amp kit when I first built his AllenAmp. It's the TP25, his specs show 320-0-320. I have 350-0-350 but no load on it. Your parts came in today so I'll wire up the rectifier and see what I get on the DC. I also realized I didn't order a 6v6 from you the other day. I need the one I put in the revibe( it's from a matched GE NOS set) that I will stuff in this build

[sluckey]

It's Allen Amps TP25 power transformer. Website says it rated for 310-0-310 @ 150mA. I have one in my Harvard 5F10. It is thick isn't it? Here's mine and the PT it replaced. Thankfully it was a drop in replacement.

[lego4040]

So I hooked up my SS rectifier and I got 630VDC, to much?

[sluckey]

So I hooked up my SS rectifier and I got 630VDC, to much?

The only way to get 630vdc out of that 310-0-310 PT is to use a bridge rectifier (or some doubler). Don't do that! You'll kill your filter caps before you even put a tube in it.

[lego4040]

  

[sluckey]

The only way to get 630vdc out of that 310-0-310 PT is to use a bridge rectifier (or some doubler). Don't do that!

Let me be more specific with that statement. What I should have said is you cannot use a full wave bridge CIRCUIT. But you can use a bridge rectifier block as a conventional full wave rectifier simply by not connecting the negative terminal to anything. Connect the other three terminals as usual and connect the HT CT to ground just as it was when you were feeding a tube rectifier.

Those little 1" square blocks usually mount with a single screw and provide a neat convenient way to connect wires, without needing additional terminal strips or standoffs.

[lego4040]

 :huh:I just pulled it out too which will take two seconds to put back. So I wouldn't hook up the negative on the DC side of rectifier your saying? I was reading Merlin's stuff on full and half wave rectifiers, will have to go back. I hooked up the Tube rectifier on a temp rig and this is the DC I got from it. I'll read up on the differences so you won't have to explain. If I go to tube I got to put it next to OT on top, then I have a heat issue since this cab isn't vented on top

[sluckey]

I was reading Merlin's stuff on full and half wave rectifiers, will have to go back.

Both rectifiers we are discussing are FULL WAVE rectifiers. The typical single diode bias rectifier that we are so familiar with is an example of a HALF WAVE rectifier.

Rather than punch a hole for a rectifier tube, I'd just go ahead and use the bridge block without connecting the negative terminal. It's not gonna make much difference in a cathode biased amp.

[lego4040]

 

[lego4040]

Back in, negative DC on the SS CAPPED and not connected to anything. Next is the multiple cap

[sluckey]

I can't see anything in the tiny pics you are posting in this thread. Doug's requested size limit is...

Please reduce your images to a max of 1024 pixels wide and 800kb or smaller

So, take the size on up to say 1024 x 768. And shine a light on the chassis! Then we will be able to enjoy your build much more. And no one will be mad at you for pic size.