Self Built (Point to Point) Budget Doom Head for 400 bucks, Orange based circuit

[Hemisaurus]

I tried adding the kit, it's $495 or $500 in real terms, with free shipping in the US.

Correction please Mr. Moderator

[dunwichamps]

I tried adding the kit, it's $495 or $500 in real terms, with free shipping in the US.

Correction please Mr. Moderator

I get em for 400 at CE Dist, that why i brought it up, its now cheaper than a weber

http://ecx.images-amazon.com/images/I/61i9PGR4%2BfL.jpg

Not much front panel space makes me think that its not easily done to run the signal all the way to that end of the chassis

[Hemisaurus]

I wondered why the had the input jack all the way on the left by the power, that's the pilot light  

What's the back panel space like? Orange used to have the Presence back there on the 200's because they were based on the slave chassis, and the presence is part of the power section. Is that logo a badge or painted on? I'm thinking people might want to drill a couple of extra holes there. I love the Bax stack, as you'll notice from my other posts, but I don't know if it's flexible enough for guitarists, without a FAC, Boost or Presence.

I guess the options are, deal with it, add on a box, drill more holes, or use concentric pots for Bass/Treble and maybe Gain/Master I don't like concentric pots generally but they would save panel space.

I would avoid tag strips and go with a custom build Turret layout, its a lot easier to work it that way. I have done both and making ur own layout to avoid noise and optimize the grounding scheme for a sweet amp is better than following an old design.

[dunwichamps]

I wondered why the had the input jack all the way on the left by the power, that's the pilot light  

What's the back panel space like? Orange used to have the Presence back there on the 200's because they were based on the slave chassis, and the presence is part of the power section. Is that logo a badge or painted on? I'm thinking people might want to drill a couple of extra holes there. I love the Bax stack, as you'll notice from my other posts, but I don't know if it's flexible enough for guitarists, without a FAC, Boost or Presence.

I guess the options are, deal with it, add on a box, drill more holes, or use concentric pots for Bass/Treble and maybe Gain/Master I don't like concentric pots generally but they would save panel space.

Im trying to avoid too much extra drilling but yes you can do all of that

IMO Boost and Presence controls are okay but i dont think they are needed given the range a treble control on a bax has

[bitter]

What does the boost function do exactly? I've notice some of the OR80's have them and some don't.

[Hemisaurus]

As you turn it up, less bass is allowed through, as it's an adjustable cathode bypass.  Your basically monkeying with the frequency response of the driver circuit. So it's like a strangle control for bass.

Modified to remove drivel of crap

Here's a graphical explanation, this page used to exist on Geocities, and I retrieved it from the Internet Archive, but the pics were broken, so I copied it to my own server to fix the pics, it is not my work.

http://dub.greboguru.org/orange-stack.html

[Hemisaurus]

FAC and Drive control wiring from the Lead 200, taken from http://planetoftheamps.com

[bitter]

Right on, Hemi. Thanks for the clarification. 

[dunwichamps]

The boost only affects hi end, its a band pass based boost circuit with a 2mH choke and a 470nF cap, thats really focused on the upper end of the freq spectrum, plus it is part of the NFB loop. Estimated center frequency is ~5.2 kHz

Check the schematic for an early OR,



When its turned down, you have a balanced cathodyne driver response, but when its up you get a lot of high end gain. But mostly its adding a lot of noise 2 at that higher freq range so lead dress is critical to avoid any problems with NFB loop running back across the amp.

Now the Drive control used on some of the GT-120s controlled how much loading was on the first gain stage and the bright cap on the volume pot. When turn up, the loading is removed from the amp and the bright cap is applied for maximum signal to the volume pot.

Sorry if my correction seems dickish, just trying to make this clear. I think you can get rid of Presence and Boost and still be fine as long as u have some NFB installed in the amp to dampen the power amp. If possibly we may get a FAC control in here but its not so easy if that logo is fixed on their. Its possible on the back panel but the layout has to make sense since this control comes off the plate resistor and coupling cap.

[bitter]

No, it's good. I like that both you guys are sharing information. I'm pretty thickheaded with this electro-wizardry, so the more the merrier. Feel free to dumb it down some  .

So does the boost contribute much to tone shaping in the pre-amp or is it really mild/less than noticeable like some presence controls?

[Hemisaurus]

It's amazing the little differences between amps



that was what I was talking about, they didn't bother with inductors on all of the models, a lot of them were just a simple (read cheaper perhaps) cathode bypass cap.

It was one of those controls that depended how hard you were pushing the amp. It seemed to have more effect when the amp was pushed hard, it's been 15 years or more since I had an Orange on the bench though, so you're pushing my memory here. I was driving on the left, eating chips and Pot Noodles, and living the bachelor life

Found a cleaner schematic

[Hemisaurus]

Dug this up, hopefully it displays OK.




Is this what they mean when they say someone has taken you back to school? Haven't thought about this stuff in years

[Hemisaurus]

Now the Drive control used on some of the GT-120s controlled how much loading was on the first gain stage and the bright cap on the volume pot. When turn up, the loading is removed from the amp and the bright cap is applied for maximum signal to the volume pot.

Now worries, I only included the Drive control because it was there. I don't think an attenuator or a bright cap is necessary, and it always seemed dumb to have a 4 position rotary switch instead of a couple of toggles, maybe it was for aesthetics. I think they used to be called Stage Normal / Stage Bright / Studio Normal / Studio Bright, but of course padding it down in the first stage affected the tone throughout the rest of the circuit, it didn't just make it quieter.

[Hemisaurus]

I've searched every site I could think of, that makes sense (Mouser never makes sense), for 1M concentric pots with no luck, 500K log seems to be the highest, unless you start trolling eBay for surplus. I can spitball the following ideas.

1. Redesign the tone stack for 500K pots. Put FAC in spare space.
2. Replace the volume with a concentric pot, use the other element for a small coupling cap, and a larger cap with the pot element, this would be FAC-ish.
3. Looks like there's enough room beside the input jack for 3 mini toggle switches, fit 4 caps on there default, small switch, medium switch and large switch you have 9 or 10 options with between OFF/OFF/OFF (just default) and ON/ON/ON (default+small+medium+large)
4. Rube Goldberg time, you can make 1M concentric pots by butchering some regular 1M pots and a similar sized concentric pot, just exchange elements.
5. External FAC box
6. Back panel FAC
7. No FAC

[dunwichamps]

the OR 200s a tad different of an amp, Orange is fond of changing schematics in the 70s.

IMO you can do a simple DPDT on off on switch and you would get 3 mods of operation, just // some caps after the 2nd gain stage to get a FAC esque control. In the off mod you could have the least bassy setup with say a 10nF cap, then one way you add 22nF while the other way you could add 47nF. fine tune this shit as you see fit.

i dont think a concentric pot is worth the cost, its a bitch to put all the components on it where as I can mount all of the bax stack components on the 2 pots easily for the best layout possible.

[Hemisaurus]

It's quite do-able.



but that was only one idea.

Yeah, it's weird, it looks like all the post 72 amps didn't have the inductor (that second schematic is not from a 200), but then the 200 itself is a Mat design which puts it pre 72. So perhaps the idea was adopted from the 200 and applied to the rest of the models? Perhaps it was the great inductor famine

Academic as you don't have panel space for it anyways. Do you include an inductive boost on some of your own models?

[dunwichamps]

It's quite do-able.



but that was only one idea.

Yeah, it's weird, it looks like all the post 72 amps didn't have the inductor (that second schematic is not from a 200), but then the 200 itself is a Mat design which puts it pre 72. So perhaps the idea was adopted from the 200 and applied to the rest of the models? Perhaps it was the great inductor famine

Academic as you don't have panel space for it anyways. Do you include an inductive boost on some of your own models?

That picture is a little far from the reality persay, it doesnt take into account the size of the components. Its doable dont get me wrong but its not the easiest. You can run a bax on 500k log no problem. The thing is that concentric pots are going to cost you extra for the pot and knob so thats something to consider.

Heres a gut shot of the metro which has a bax

http://img3.imageshack.us/img3/7845/gut5.jpg

Its hi res so zoom in and you can see how I laid it out on 2 pots (plus shift control)

I assume they dropped inductors because they are expensive.

[Hemisaurus]

Concentric pots were only one idea, and like you say it's do-able, those don't look like fullsize pots in the Metro, you could fit those caps you've used, and it would be $23, $11 for the pot $12 for a knob set.

Yeah, I can't recall ever having worked on an Orange with that inductor, it must have been shortlived.

Anyway, please don't bust a gut trying to fix it unless other people wanted a FAC. I'm only talking hypothetically, I wouldn't be buying one.

[dunwichamps]

Concentric pots were only one idea, and like you say it's do-able, those don't look like fullsize pots in the Metro, you could fit those caps you've used, and it would be $23, $11 for the pot $12 for a knob set.

Yeah, I can't recall ever having worked on an Orange with that inductor, it must have been shortlived.

Anyway, please don't bust a gut trying to fix it unless other people wanted a FAC. I'm only talking hypothetically, I wouldn't be buying one.

Pots in Metro are PEC 2W milspec 24mm full size I believe. Only early 70s ORs had those inductors which give the Boost a little different behavior.

My idea with this MOD kit is that we on StonerRock could develop a nice little 50W OR type build that would be great for users who are looking for a vintage amp which they could rip on for a reasonable price. As long as users can build it. I think its a worthy investment, as you do not need me to build you something. I believe anyone on here could learn to build a nice amp

[Hemisaurus]

Yeah, I think I said I only saw it in schematics for some pre '72 Oranges. I wouldn't have seen any of the recent post 90's Orange's, I was married and emigrated by then. I think Orange were gone, or very quiet for the 80's and 90's. I don't recall any new stock around. I imagine I was working mostly on the mid 70's gear. I should also have noted that in the OR200 the 'boost' is called presence and mounted on the back panel, and there's a different control for 'boost' which is on the cathode of the second triode instead.

I guess I don't get the idea in that, are we ordering the kits from you, where you get the original kit, and add / subtract whatever is needed for your particular design, and then ship it to us. Or are we ordering the kit through you, to be drop shipped to us, and then we all generate a list of any extra parts we need?

It's a nice kit in that it has Hammond xfmrs, and good caps and all, but the lack of front panel space makes it kind of limiting hence me trying to come up with a way we could at least get a little more tonal variation. It's more of a tube tweaker or circuit tweakers kit, than a players kit.

As an aside, and I mentioned something like this in another thread, have you thought of generating MOD boards yourself for peoples current amps? You could have a stock of semi-built turret boards and people could retrofit their current amps, or buy a beater amp and turn it into something nicer? You could either add the necessary tweaks yourself on demand (to handle the differences in tube driving) or just supply instructions?

Just a thought, I think I said I should start a service doing the mods myself for cost of parts plus a flat fee, but this would be more DIY for people and might be a revenue stream for you?

[dunwichamps]

Yeah, I think I said I only saw it in schematics for some pre '72 Oranges. I wouldn't have seen any of the recent post 90's Orange's, I was married and emigrated by then. I think Orange were gone, or very quiet for the 80's and 90's. I don't recall any new stock around. I imagine I was working mostly on the mid 70's gear.

I guess I don't get the idea in that, are we ordering the kits from you, where you get the original kit, and add / subtract whatever is needed for your particular design, and then ship it to us. Or are we ordering the kit through you, to be drop shipped to us, and then we all generate a list of any extra parts we need?

It's a nice kit in that it has Hammond xfmrs, and good caps and all, but the lack of front panel space makes it kind of limiting hence me trying to come up with a way we could at least get a little more tonal variation. It's more of a tube tweaker or circuit tweakers kit, than a players kit.

As an aside, and I mentioned something like this in another thread, have you thought of generating MOD boards yourself for peoples current amps? You could have a stock of semi-built turret boards and people could retrofit their current amps, or buy a beater amp and turn it into something nicer? You could either add the necessary tweaks yourself on demand (to handle the differences in tube driving) or just supply instructions?

Just a thought, I think I said I should start a service doing the mods myself for cost of parts plus a flat fee, but this would be more DIY for people and might be a revenue stream for you?

My idea is to provide information, design, and access to CE prices. I do not plan on making money from this. If forum members want to make it work all I will be is a middle man who orders and drop ships the shit to your door.

The lack of front panel room is part of the compromise we have in using a 400 dollar kit. You could upgrade to a 600 dollar Weber setup and get a fullz size amp with more flexibility but you wont get as nice tubes and trannies so there is more money needed say for all JJ tubes and nice Hammond trannies. I think this amp could b good for a grip and rip kind of approach. Get yourself a fuzz pedal, dial in the amp, and rip.

I have never thought of suppling Turret boards with prelayed out preamp circuits. I guess if someone asked I would do it. Given the custom work I do I am always coming up with new stuff, new layouts. If people wanted a board for the MOD kit I could supply that.

Mods for what? other amps?

[Hemisaurus]

No I meant a board for any amp, not necessarily a MOD amp.

I mean you already have a preamp there, and I imagine you have other designs that have more knobs, have your 'orange-esque' design or your 'sunn-ish' design or your 'dunwich homegrown' design, you can build the preamp, attach pots and valve sockets even, and offer that as a 'kit' for people to replace their own preamp with, and offer instructions on how to deal with the power supply, maybe even throw in a couple of strips and the parts for the PSU, caps or whatever. It was, like I say, just a thought to utilize what people have, whilst getting a better sounding amp. Sort of like Ceriatone where they offer a complete board, for other models.

That way people can take their beater Peavey, Crate, Bugera, B52, Sovtek or whatever and replace the preamp as a single board, and then add the power supply stuff.

That was what I had mentioned in the other thread the 'send me your amp and for $N of parts and a flat fee, I will turn it into a Sunn/Orange/Plexi' service I should, and maybe will, offer.

I think a lot of this stems from working mainly on British gear, where there are the pots, the tubes and a turret board or small PCB, wired to all of it. Rather than everything on a PCB as is the modern way. You think of all amps in that sense, throw away the PCB, put in proper valve sockets and pots, and hardwire it all together. You'd be supplying the PCB / turret board in the middle, the heart of it.

[dunwichamps]

No I meant a board for any amp, not necessarily a MOD amp.

I mean you already have a preamp there, and I imagine you have other designs that have more knobs, have your 'orange-esque' design or your 'sunn-ish' design or your 'dunwich homegrown' design, you can build the preamp, attach pots and valve sockets even, and offer that as a 'kit' for people to replace their own preamp with, and offer instructions on how to deal with the power supply, maybe even throw in a couple of strips and the parts for the PSU, caps or whatever. It was, like I say, just a thought to utilize what people have, whilst getting a better sounding amp. Sort of like Ceriatone where they offer a complete board, for other models.

That way people can take their beater Peavey, Crate, Bugera, B52, Sovtek or whatever and replace the preamp as a single board, and then add the power supply stuff.

That was what I had mentioned in the other thread the 'send me your amp and for $N of parts and a flat fee, I will turn it into a Sunn/Orange/Plexi' service I should, and maybe will, offer.

I think a lot of this stems from working mainly on British gear, where there are the pots, the tubes and a turret board or small PCB, wired to all of it. Rather than everything on a PCB as is the modern way. You think of all amps in that sense, throw away the PCB, put in proper valve sockets and pots, and hardwire it all together. You'd be supplying the PCB / turret board in the middle, the heart of it.

that would be pretty kool but i do not know how much time I would have to actually build boards as I have builds for a while (next month maybe till May) but if you want some designs to use I dont mind supplying some stuff.

[Hemisaurus]

I think a good thing to have would be a layout, rather than a schematic then, of whatever design you care to throw at people. A layout and a parts list, and most builders are set.

Then again, absolutely no-one else has chimed in here, so maybe everyone is happy with the MOD kit, or nobody is wanting to build their own amp.

[dunwichamps]

I think a good thing to have would be a layout, rather than a schematic then, of whatever design you care to throw at people. A layout and a parts list, and most builders are set.

Then again, absolutely no-one else has chimed in here, so maybe everyone is happy with the MOD kit, or nobody is wanting to build their own amp.

I can work with a general layout, with 2 pretubes you need atleast 1 for a phase inverter. So 2 gain stages + an LTPI or 2 gain stages into an AC coupled Cathodyne. a Bax stack is the best 2 knob tone stack but an FMV would work with fixed mids controls (barring the use a concentric pot). The cleanest build would be a single common cathode stage coupled to a DC follower into the tone stack into an LTPI while the Orange would have a lot of gain