Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: ratgon on April 08, 2016, 04:17:05 pm
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Hey all. How've ya been? I've been away for awhile but finally back home and stoked to be getting back into it. I was wondering about all of your different methods of prototyping amps. If you have any tips or systems you use and pics I'd love to hear/see them..
I'm really interested in how you handle transformers to allow for a variety of designs. Obviously some idea of what I want to build determines what trannies I'll use but maybe there are some assortment of trannies that will allow for a range of possible designs.
Anything you all use or do for prototyping would be of great interest to me.
Thanks!
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Search bar -> "breadboard" -> This board
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A bench PS like this one is very useful for breadboard prototyping.
Ones like this are hard to come by, and can be expensive.
But well worth the investment if you plan to do much prototyping.
You could build something similar from scratch, but it will still be expensive. :icon_biggrin:
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To create a breadboard that can handle "everything" from a Champ to an SVT with 4 fat output tubes is a large project. Some of the ones some forum members built were quite impressive, nice builds in and of themselves, though they would cost for all the nice new parts.
What do you wish to concentrate on? Preamps? Power supplies? Smaller amps with 2 push-pull tubes or monsters?
I have two elements for breadboarding. The 6G2 is not fully built, still in a larval stage.
1: is a CONN organ oscillator module (a lower end CONN organ will have 6 or 7 of these) that used to have 6 qty 9-pin tube sockets in it. Cut out a hole for a transformer and build a simple supply and this is good for preamps. The CONN had tons of terminals strips on it which I tried to leave behind. Threw a switch and a fuse in there. The tubes run upside down. The Tek scope transformer is massive overkill of course but I sometimes use this to power other junk. The diode bridge is set up to easily change the B+ level because it takes its AC from two of the 3 or 4 windings on the PT, in series. Those windings are 210 VAC and 137 VAC, something like that. Yes, I have a bench power supply with a big knob on the front but it's just one less piece of gear involved. Preamps use miniscule power.
2: will be a complete Princeton 6G2 on a plate of metal. Dummy tubes for pix purposes. This is to test out output transformers. I get a fair amount of salvage audio output trannies and this is for testing them out. It is built upon a piece of sheet aluminum hacked out of a scrapped Tektronix scope, that already had the punchouts for the tube sockets. Incidentally....from dead computers, you could get 4-wire MOLEX connectors for free and use them to rig up an output tranny and/or to swap others in. Plate-HV-plate-feedback connection. Could do the same with B+/gnd/heater/heater. Don't mix them up!
(http://i172.photobucket.com/albums/w32/ttm4/2004-12-31%2023.00.00-7_zpskzyzug5m.jpg) (http://s172.photobucket.com/user/ttm4/media/2004-12-31%2023.00.00-7_zpskzyzug5m.jpg.html)
(http://i172.photobucket.com/albums/w32/ttm4/2004-12-31%2023.00.00-8_zpsivbjuvnu.jpg) (http://s172.photobucket.com/user/ttm4/media/2004-12-31%2023.00.00-8_zpsivbjuvnu.jpg.html)
(http://i172.photobucket.com/albums/w32/ttm4/2004-12-31%2023.00.00-5_zps42bkgieo.jpg) (http://s172.photobucket.com/user/ttm4/media/2004-12-31%2023.00.00-5_zps42bkgieo.jpg.html)
(http://i172.photobucket.com/albums/w32/ttm4/2004-12-31%2023.00.00-6_zpsdpxfpdnw.jpg) (http://s172.photobucket.com/user/ttm4/media/2004-12-31%2023.00.00-6_zpsdpxfpdnw.jpg.html)
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You are my salvaged gear hero, eleventeen! :worthy1:
Ratgon, I think you are starting to see that there are many ways to skin this cat.
As eleventeen pointed out, it really depends on your application.
If you plan on focusing on lower voltage, low wattage, cathode biased circuits, you can build your own rather inexpensively. :icon_biggrin:
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I'm really interested in how you handle transformers to allow for a variety of designs. Obviously some idea of what I want to build determines what trannies I'll use but maybe there are some assortment of trannies that will allow for a range of possible designs
I prefer PT's with standup mounting rather then thru chassis mounting but have used both. I just like more room inside the chassis of my scratch builds.
I like 300-0-300 PT with 150ma ................ or 275-0-275 PT with 150ma (sometimes 100-120 ma is OK)
5Y3GT 300 x 1.1 = 330v EL84, 6V6, 5881/6L6
5V4 300 x 1.2 = 360v 6V6, 5881/6L6
GZ34 300 x 1.3 = 390v 6V6, 5881/6L6
solid state 300 X 1.4 = 420v 6V6, 5881/6L6
IF you had a 300-0-300 with 175-200ma then you could possibly include EL34 or KT66 tubes
5Y3GT 275 x 1.1 = around 300v EL84, 6AQ5, 6K6, 6BM8
** It is critical that you figure out the heater current of the PT's and the tubes you use also. Check out the Tube Data
Cheat Sheet attached.
Those PT's would cover any tube amp that I would build for myself except the ECL84 So-Low Watt which would need lower voltages on the plates.
With respect, Tubenit
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Thank you all for the help! It's appreciated! Lots of good ideas!
I'll keep ya posted as I put them to use
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Ratgon, did you do the search? There are some long threads on a couple very-complete breadboard setups. I ask because to find the thread to link, I'd have to go do the search myself (in fact, I did just to make sure it would return results for you).
Meanwhile, I have been visiting another forum where recently, members were agitated by someone finding a thread that is 7-9 years old and commenting on it as though the conversation were continuing now. Obviously, they had to go do a search just to find that thread, which provided info to answer their questions.
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Hey all...thanks again and sorry for getting back so late. i'm about to search and get some more ideas. I've put together a board that i've been using for some small mod circuits and it's constantly changing but the transformer choices are what I guess I need to nail down.
Thanks again.
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Looking great!