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Old 15th June 2011, 03:00 AM   #81
bst is offline bst  United States
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The idea of using junkbox parts, or parts already on hand, and then tallying the equivalent current purchase price, is an excellent suggestion. I didn't realize that there were many prospective builders who have a problem with slow parts deliveries.

Eliminating a completely enclosed metal chassis from the total price is also a reasonable idea. Builders who choose to assemble on a metal top plate (or other suitable material), and then enclose the completed amp in any enclosure which precludes shock hazard is fine. The object is to prevent animals and children (and impulsive adults) from getting a potentially fatal shock from exposed high-voltage circuitry. Obviously, one can never prevent all potential hazards. A toddler can still grab a hot tube, or drop the whole amp on his instep, requiring dried tears or even a trip to the doctor's office. But as long as there are no hot chassis, ungrounded line cords, or readily-accessible high-voltage points, you should be good to go. Prudence, but not paranoia, should dictate your final product.

Edited to add: tools and test equipment need not be included in the construction cost. If I included the cost of my Milwaukee metal chop-saw I'll use to cut off my cheapskate chassis material, I'd be way over over budget before I even started.

Last edited by bst; 15th June 2011 at 03:08 AM.
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Old 15th June 2011, 07:56 AM   #82
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Quote:
Originally Posted by Trout View Post
A couple things that really stick out in my mind on building guitar amps in general has to do with a aspects not included in the challenge.

The speaker.

For example,
take a common 5W SE Champ, or a 14W Tweed Deluxe or even a 100W Marshall, the end tone is greatly affected by speaker choice.

Often guys find that all of the design mods and tweaks possible will never compete with a speaker intended for a specific design & music genre.
Size, type of magnet, and so on.

How will the end design be judged? on a scope? dummy loaded? mathematical theory?

Recording;

If recorded clips are used, there can also be a 2 fold disadvantage.
Some guys can make darn near any amp sound fantastic, others like myself not so much.

Recorded clips can be improved through clever use of the various recording software's. For instance, the clips I posted above have a bit of reverb added post recorded.
It is fairly easy to doctor EQ's as well.

Just a bit of food for thought.
I don't understand how these two critical factors are to be normalized. If the results are to be judged by a sound clip, the winner will likely be the one using a 4x12 cab and a killer recording setup.
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Old 15th June 2011, 09:38 AM   #83
tubekit is offline tubekit  United States
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Default The challenge, if you choose to accept it, Mr. Phelps, is . . .

If this challenge were an attempt to better the belittled amp that started it, then it would be a challenge to see who could build the LOWEST COST MINIMALLY USEABLE TUBE GUITAR PRACTICE AMP. Since it is not, and since no one has simply pointed to some (other) obvious candidate for that distinction, I must continue to believe that the amp which started this thread, despite some of the rather caustic (yet unsupported) comments demeaning it, does, in fact, hold that distinction. Pending revision, I will hasten to humbly admit of course.

But if you do take up that challenge, you may wish to be prepared to discover that the task was not so easily accomplished as was once so spontaneously thought.

For my part, I am reciprocally willing to discover that my challenge is not so difficult as I now think it to be and to defer to your superior product . . . JUST AS SOON AS ONE OF YOU ABLE GENTS CREATES AN AMP THAT BETTERS IT AND MAKES IT AVAILABLE FOR SALE TO THE PUBLIC or, for that matter, points to ANY such real, existing item.

Keep in mind that after one has created it, one has to sell it. It isn't at all useful to the first-time tube experimenter and sometime guitar player if you simply tell him/her that you once made such a thing and show a photo of it gathering dust in your basement. This means that SOMEONE has to put the parts in a bag, count them, put the bag in a box, make the shipping labels, (pay ebay and paypal) and ship the things -- all for the quoted price, of course. (NOTE: If anyone tires of this after two weeks, it doesn't count. The customers can have no confidence in its value after such a betrayal.)

But we're here, now. Okay, I, too, will take YOUR challenge, THIS challenge, the simpler one that THIS thread is about -- the great-sounding guitar amp for less than $100 challenge -- PROVIDED THAT

--->>> all parts except the chassis, cabinet and speaker must be NEW or NOS parts readily available to everyone and priced at today's prices and the audio path must be ALL-TUBE. (nothing salvaged from an old TV is new) <<<---

(You want to use a 12AX7? At today's prices??? And what will you leave out in exchange for that luxury?)

Otherwise you're all just flattering yourselves. If you're not opening up an opportunity to another person, a person who, but for your efforts, would not be able to do what you can give him/her the tools and the knowledge to do, then you're just wasting your time. And if it isn't repeatable for X number of people, then it's just a one-hit wonder, a curiosity and nothing more.

You can't sell something NEW that you fished out of your basement. And you can't invite the world into your basement to fish around in your junk to duplicate what you did last summer. If you can't offer them over-the-counter parts and the complete how-to-do-it in a single package, then you're not doing much more for The-New-Guys than just showing them your awards. And that isn't going to be of much use to another human being 1000 miles away on a limited budget who simply wants to play a guitar through a TUBE AMP in his/her apartment and NEEDS A SUITABLE AMP.


I won't tire you further by repeating what I recently posted in the thread that started this, but I will mention it. For those of you who wish to add some relevant background to all the excitement going on here, I refer you to posts #34, 35, and 36 in the original thread from which this one sprung.



To the challenge! A great-sounding 2- to 5-Watt tube amp for guitar practice for less than $100 in new parts!

May the most deserving entry win.
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Old 15th June 2011, 09:50 AM   #84
tubekit is offline tubekit  United States
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Default Which junkyard parts? Buyable ones or obsolete ones?

Quote:
Originally Posted by bst View Post
The idea of using junkbox parts, or parts already on hand, and then tallying the equivalent current purchase price, is an excellent suggestion. I didn't realize that there were many prospective builders who have a problem with slow parts deliveries.

Eliminating a completely enclosed metal chassis from the total price is also a reasonable idea. Builders who choose to assemble on a metal top plate (or other suitable material), and then enclose the completed amp in any enclosure which precludes shock hazard is fine. The object is to prevent animals and children (and impulsive adults) from getting a potentially fatal shock from exposed high-voltage circuitry. Obviously, one can never prevent all potential hazards. A toddler can still grab a hot tube, or drop the whole amp on his instep, requiring dried tears or even a trip to the doctor's office. But as long as there are no hot chassis, ungrounded line cords, or readily-accessible high-voltage points, you should be good to go. Prudence, but not paranoia, should dictate your final product.

Edited to add: tools and test equipment need not be included in the construction cost. If I included the cost of my Milwaukee metal chop-saw I'll use to cut off my cheapskate chassis material, I'd be way over over budget before I even started.

Keep in mind that there are no "equivalent current purchase price(s)" for parts that can no longer be obtained. If the part is not currently available, then the amp cannot be duplicated by another except by the remotest chance, is therefore of very limited use, and should not be an eligible contender.

I've said it before, but it's worth repeating: if this is nothing more than a quest to find out what some old-timers can build from the parts they have in their basements, then it is completely useless to a new generation of tube amp aficionados, and veers wildly off tangent from the boast and counter-boast which started it. Under such conditions, this challenge is utterly pointless. Who cares if you can build an amp for nothing? The question is, how can Young Everyman build your sure-fire amp from your design?

Substitute the output transformer you pulled from a TV for one Everyman buys online and the sound is different and the whole thing is a waste of time.
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Old 15th June 2011, 10:07 AM   #85
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Quote:
Originally Posted by tubekit View Post
If you can't offer them over-the-counter parts and the complete how-to-do-it in a single package, then you're not doing much more for The-New-Guys than just showing them your awards.
Nonsense , I don't think I've ever bought a kit, even when I was a very raw newbie.



At the moment, you're just shilling for business, and that's not how we do things here. Show us some schematics, give some helpful circuit design tips or buy a thread in the Vendors Forum. Your call, but whilst you keep spamming you'll stay under moderation.
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Old 15th June 2011, 11:07 AM   #86
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Originally Posted by tubekit View Post
I won't tire you further by repeating what I recently posted in the thread that started this, but I will mention it.
I will say I won't do it, and then say I will do it in the same sentence? Not really wanting to say you are sounding real whinny, but...

Quote:
To the challenge! A great-sounding 2- to 5-Watt tube amp for guitar practice for less than $100 in new parts!

May the most deserving entry win.
Given the constraints some of us have I do not see why we can not use a 30VA transformer or tube sockets that we have and use a comparable value for that item as being sold now.
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Old 15th June 2011, 11:31 AM   #87
SY is offline SY  United States
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I think he has a point. Your surplus transformer would have to have the same DCR and saturation characteristics as well as the same power/current rating as a new unit. Otherwise, the amps could sound quite different. These are designs meant for other people to duplicate, not one-offs. My view, anyway.
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Old 15th June 2011, 01:28 PM   #88
TheGimp is offline TheGimp  United States
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Even the power transformer can make a difference if there is B+ sag at full output.

If the power transformer is over-rated and B+ does not sag much it may not matter.

OPTs definatly matter.
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Old 15th June 2011, 01:48 PM   #89
Cassiel is offline Cassiel  Libya
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I think he wrote a good post but that won't stop me from using junk parts from my basement. I don't think a cheapo OPT the size of a thumbnail is going to sound better than new Edcor's or Hammond's but it is true it will sound different. Still, I am a DIYer at heart and I do things my own way. My project not eligible to win? It's OK to me, I wasn't going to win anyway.
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Old 15th June 2011, 01:59 PM   #90
SY is offline SY  United States
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That's it exactly- if one of the design goals is that it's only for one's own use, all sorts of interesting oddballs can result (most of us old timers have some pretty unusual parts in our junkboxes). If it were just for me, I'd rewire my guitar for balanced out and have the amp be balanced in. But that will have an audience which could be counted on the fingers of Harold Russell's hands.

If the design goal is to create the Everyman Amp, the constraints have to be different.
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