Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: EKDENTON on June 26, 2016, 10:49:12 pm
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I am starting a scratch build and want to document progress along the way here. I could not find a layout online that looked like a working layout. The folks at the Orange amp forum say a layout is a "trade secret". The store bought Tiny Terror is a PCB/tube amp that is manufactured in in various countries. I have been listening to many different sound clips and the amp does have a nice sound to it, its small and very portable, simple only three pots (gain, tone, volume). Orange does make a point to point hand wired version that is very expensive. So I decided to try to build one by the schematic.
After ordering the transformers from Mercury Magnetics (which was the only place I could find a PT with the secondary taps for the 7/14 watt switch) the "Kit" arrived. It is an "upgrade kit" that converts a Tiny Terror to a Holy Terror. I tried to incorporate these upgrades to my layout but one of the upgrades (a voltage divider) would change one half of the dual gain pot to a tone control that would change the tone anytime you changed the volume. After confirming with MM that their schematic was correct, and with the advise of some of the more experienced amp builders here I decided to just do the stock build. Then I can always make adjustments once I get the amp working if adjustments are needed.
Even though it may be a bit like building a ship in a bottle I am trying to stay with the same size chassis as the store bought amp. Rather than I complete four sided cover for the tubes I have just bent a 3/16 thick aluminum cover to protect the tubes. The chassis is painted and drying (not the same color as Orange amps LOL). This week I am going to work on the turret board. I have always used resistors rated higher than needed but this time I need the space so the board resistors will be the 1/2watt carbon comp.
Once I get the amp to work I will post the layout photo, the turret board layout, and the BOM if anyone else is interested in making one.
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I'm in for the ride. Personally don't think the secrete layout will make much difference as long as what you come up with follows basic rules of engagement.
silverfox.
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Very nice
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WOW !
that is a very sturdy chassis :thumbsup:
Franco
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EKDENTON I am interested in this amp. Would very much like to see the photos completed and turret board layout. What kind of metal brake did you use to bend the chassis?
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I own a metal shop and mostly sell steel but I have access to aluminum. I have a 10ft Durma shear that has a capacity of 1/4" steel and a 10' Whitney Roper leaf brake, and also a 42" Grizzly box pan brake. I have a little stomp notching shear to cut the corners out before folding. So the chassis part of amps are easy for me it's all the other parts and circuits of an amp I am still trying to learn. I should have some parts in today to continue the turret board so I will post progress photos soon. Should be a fun project.
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I give a look to your shop :thumbsup:
Franco
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I'm wiring the transformers now and I was looking at the drawing and the filament wiring on the plan looks different from what I am used to. The last few that I have done that did not have a center tap on the filament winding, I used Doug's drawings for the artificial center tap. I attached both. The bottom is from Doug's library.
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Do it like the bottom pic.
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Very good work !! Looks beautiful !!
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Okay will do it like the bottom picture. That's how I did the last amp.
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I finished this amp. Worked first try with no troubleshooting needed. Here are some photos, and links to the tube voltages in the 7 and 14 watt modes. Also i listed the power supply voltages on the notes.
http://el34world.com/charts/valve/ValveData.php?e=view&f=19482 (http://el34world.com/charts/valve/ValveData.php?e=view&f=19482)
http://el34world.com/charts/valve/ValveData.php?e=view&f=19481 (http://el34world.com/charts/valve/ValveData.php?e=view&f=19481)
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Very nice job!
1 of your turrets looks like it might not have gotten soldered.
The one where the 2 resistors come together on 1 turret.
It looks fantastic otherwise. :icon_biggrin:
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It wasn't quite finished yet, I was waiting for the tone cap to arrive 😊 in the next to last photo I was waiting for screen, and grid resistors. I will get an updated photo of the inside tonight.
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Very nice! Looks just like your layout drawing. Now when people come to you and say where did you get that layout, you can tell them it's a big secret! :laugh:
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I removed the .22 cap between the input jack and the 68k resistor at V1 pin2. It is not necessary. I also moved everything over to allow more room for the bias resistor so it is not directly against the capacitors on either side of the bias resistor. The original schematic has a 5K but I changed that to a 10k.
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:thumbsup: :thumbsup:
Solid
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Can you post a higher res photo of the layout? You can't really see what the parts are, thanks.
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I don't know where I got the attached layouts but how do they it compare to yours circuit wise?
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I removed the .22 cap between the input jack and the 68k resistor at V1 pin2. It is not necessary. I also moved everything over to allow more room for the bias resistor so it is not directly against the capacitors on either side of the bias resistor. The original schematic has a 5K but I changed that to a 10k.
Hello!
I now this topic is a bit old, but, anyone have this layout image in a better quality?
Really liked this design.
Cheers
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At the time I saved the Layouts on this thread but, unluckily the Layout that is of your interest was never posted in high resolution
Franco
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https://www.tdpri.com/threads/tagboard-terror.1093062/
This is what I used along with the above thread to stutter through my completed build.
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At the time I saved the Layouts on this thread but, unluckily the Layout that is of your interest was never posted in high resolution
Franco
Oh man
Thanks anyway
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https://www.tdpri.com/threads/tagboard-terror.1093062/
This is what I used along with the above thread to stutter through my completed build.
Amazing layout too.
Thanks for sharing!
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After some research, i've decided to give a crack at this layout:
Here it how looks now:
(https://i.imgur.com/kz3iayU.png)
Now it looks a bit messy, still trying to improve.
I've used 4 caps, 'cos here where i live couldn't find the multi-cap.
All caps are rated for 450 or 630V.
My big question here is the heaters, are they wired correcty? really don't understand the original schematic with the two 100R resistors in the 6.3V rail...
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My big question here is the heaters, are they wired correcty? really don't understand the original schematic with the two 100R resistors in the 6.3V rail...
There must be a jumper between pins 4 and 5 for both 12AX7 tubes. The two 100Ω resistors make an artificial center tap and provide a ground reference for the filaments. The purpose is to reduce heater hum. It's a good thing.
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In my archive I've find this
(https://i.imgur.com/mohv5Kj.jpg)
(https://i.imgur.com/ySnynra.jpg)
The Layout seems draw by our friend Tubenit
Franco