The secret is out, better grab your tin foil hat!
My take on all of this is that it is relatively disingenuous marketing claptrap. The guys who designed this were looking for clever and inexpensive ways to build a glamorous looking, but simple low cost design using mostly if not all locally available off the shelf inexpensive components. Who knows maybe they found a huge stash of GM70s cheap - even here they don't cost much.
Can't wait for American buyers to try and source replacement light bulbs for this amp - that should prove just a little entertaining as they are not available in that voltage rating at any home center here. In fact finding any 25W bulbs in most stores around here has become a minor challenge.
You can even see the lip on the end attached to the chassis panel. Sure looks like one to me
I think they have a name for this: "Adaptive Reuse" illustrating clearly that the designer of this amp does not suffer from "Functional Fixedness."
In the interest of honest disclosure I have a pair of Progresso soup cans awaiting a similar fate - they are just screaming for some ill-advised use such as this..
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Ugh, I had a huuuuge reply ready (involving Nelson Pass, none other) but I decided to scrap it. What bugs me about this topic is that it's the 2nd one about the same crappy company publishing same half-assed "designs" that make about as much sense left-handed shovel (we all know that people with two left hands cannot even hold this specially designed type of shovel ...).
Fine; if they manage to do their business I say power to them for finding gullible suckers but I'm certainly not going to help them by sugaring up the topics staretd by them on a puiblic forum. There are technical aspects that don't make sense as it is, let alone with their description of "qualities" supposedly associated with their "design". DF96 has quoted those, nothing to add. I mean, anybody who has finished elementary school (7th grade physics = Ohm's Law) should understand why the crap they posted doesn't make any sense, without even looking at the design (yes, primary-less transformer, I'm looking at you).
I hope this topic will achieve exactly the opposite result of what they were hoping to get - to expose the snake-oil peddlers for what they are. If they marketed their "design" as a horribly inefficient and rather heavily distorting parafeed SE amplifier (= "tube sound", the more, the merrier ?) without the crap about lower power, prolonging tube life etc., they'd be right up there with mr. Pass (heck, I couldn't help bringing him up once again), spelling it out as it is, making no pretense. If people like the results, great, they should enjoy their purchase. But with this kind of Shamwow advertising and attention-whoring they deserve to go down.
People here are knowlegeable enough to avoid such marketing traps but we should educate the random visitors that only come here for information when they are trying to decide what to buy.
Fine; if they manage to do their business I say power to them for finding gullible suckers but I'm certainly not going to help them by sugaring up the topics staretd by them on a puiblic forum. There are technical aspects that don't make sense as it is, let alone with their description of "qualities" supposedly associated with their "design". DF96 has quoted those, nothing to add. I mean, anybody who has finished elementary school (7th grade physics = Ohm's Law) should understand why the crap they posted doesn't make any sense, without even looking at the design (yes, primary-less transformer, I'm looking at you).
I hope this topic will achieve exactly the opposite result of what they were hoping to get - to expose the snake-oil peddlers for what they are. If they marketed their "design" as a horribly inefficient and rather heavily distorting parafeed SE amplifier (= "tube sound", the more, the merrier ?) without the crap about lower power, prolonging tube life etc., they'd be right up there with mr. Pass (heck, I couldn't help bringing him up once again), spelling it out as it is, making no pretense. If people like the results, great, they should enjoy their purchase. But with this kind of Shamwow advertising and attention-whoring they deserve to go down.
People here are knowlegeable enough to avoid such marketing traps but we should educate the random visitors that only come here for information when they are trying to decide what to buy.
Completely unrelated to subject at hand but you can look up "plasma tweeter" on youtube.com for visual examples and google it up for reference sircuits using tubes (this is a tube forum afterall
). in action it looks better than Bunsen burner Have we all missed the point here? We have been discussing this as though it is a real product that someone is trying to market. What if it is really a spoof, and we have all been suckered? After all, if you really wanted to sell something like that you wouldn't draw attention to it on a forum like this, would you? No, you would go for an AV forum or somewhere people don't actually understand audio electronics.
Or is it an elaborate double-bluff? We criticise it, which just goes to show we are jealous that we didn't think of such a brilliant idea ourselves.
Or is it an elaborate double-bluff? We criticise it, which just goes to show we are jealous that we didn't think of such a brilliant idea ourselves.
I have just noticed that on the other vetruvio thread someone has popped up to say that he has one of these, it is very good, and that the schematic on the website is not really accurate so it is pointless discussing it. A cynical person might regard this as a damage limitation exercise.
Interestingly, he does say something about the amp containing soup - so it is not tuna in the tins!
Interestingly, he does say something about the amp containing soup - so it is not tuna in the tins!
This. Plus it is always a gamble as crowd might just be gullible enough to fall for a silly idea and staunchly support it without any scientific reason behind it (I hate to bring up mr. Pass and his one transistor series of exercises once again ...). Dictionary says "staunchly" is a real word, much to my surprise.
The amplifier is sold on eBay and the guy who opened this thread is a forum member who was curious about the merit/lack thereof of such a design.
I have heard very similar amplifiers, as I indicated in an earlier post there was a time when this was a bit of a cheapskate fad around here, and believe it or not they do work, and they don't sound terrible either - however and this is the point, these were hobbyists experimenting just for fun, were well aware of the serious performance limitations of the approach and admitted such.
I'm not sure anyone should be selling such a design to the public, however a truthful disclosure of the technical limitations of this design, and an honest statement of the power output capability would be a good place to start. They could bill it as an experimenters amplifier and explain how it might be an economical starting point for someone wanting a GM70 amplifier.. They could even sell the "upgrade kits" to take it to a more conventional design.
In terms of tube life, the cathode current is pretty high regardless of the actual plate dissipation so I would not expect this design to have significantly better tube life than mine which will run at twice the dissipation and roughly the same current. I doubt tube life of much more than 1K hours is even likely with this tube, but until I run through a set or two in my own yet to be completed amps I don't really know. CCS heating of the filaments is unlikely and I expect filament failure kills a lot of these tubes if not a serious drop in emission. (They run really HOT)
Unfortunately these guys have probably figured out that spelling it out as it is does not result in many sales particularly on eBay.
I find it hard to believe that the published design differs significantly from what they are or have been building.. Sadly a simple plate choke would eliminate most objections to this design, and result in a significantly better performing amp even with the apparently undersized toroid they use as the OPT..
I have heard very similar amplifiers, as I indicated in an earlier post there was a time when this was a bit of a cheapskate fad around here, and believe it or not they do work, and they don't sound terrible either - however and this is the point, these were hobbyists experimenting just for fun, were well aware of the serious performance limitations of the approach and admitted such.
I'm not sure anyone should be selling such a design to the public, however a truthful disclosure of the technical limitations of this design, and an honest statement of the power output capability would be a good place to start. They could bill it as an experimenters amplifier and explain how it might be an economical starting point for someone wanting a GM70 amplifier.. They could even sell the "upgrade kits" to take it to a more conventional design.
In terms of tube life, the cathode current is pretty high regardless of the actual plate dissipation so I would not expect this design to have significantly better tube life than mine which will run at twice the dissipation and roughly the same current. I doubt tube life of much more than 1K hours is even likely with this tube, but until I run through a set or two in my own yet to be completed amps I don't really know. CCS heating of the filaments is unlikely and I expect filament failure kills a lot of these tubes if not a serious drop in emission. (They run really HOT)
Unfortunately these guys have probably figured out that spelling it out as it is does not result in many sales particularly on eBay.
I find it hard to believe that the published design differs significantly from what they are or have been building.. Sadly a simple plate choke would eliminate most objections to this design, and result in a significantly better performing amp even with the apparently undersized toroid they use as the OPT..
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I started another thread about this company before this one went up (although it hasn't seen any action because everyone is commenting on this thread) because just like Kevinkr mentioned, I was curious as to the technical merits of the design. I appreciate the comments that have reflected people's opinions on that matter.
Not all DIYers are skilled enough to jump right in to a scratch build and design something from the ground up; for us, some of these products offered from the far east and eastern Europe offer a nice alternative for a fun project. You get something that already works and you can enjoy it out of the box and then you can pick people's brains in a place like this to figure out ways to make it better. It's almost like a prebuilt kit that provides a fertile platform for experimentation. Even better, you can usually do it for cheap.
Anyway, I've enjoyed reading the comments and I do have to say, at least fit and finish wise I think my very limited funds will probably still find their way to the Chinese but I still like seeing offerings like this from other places. More options are always better for everyone but it still takes the wisdom of some of the more senior folks here to not truly waste your money. For example, I never thought to think that those light bulbs are not going to be easy to find outside of the country of origin... Good point!
Not all DIYers are skilled enough to jump right in to a scratch build and design something from the ground up; for us, some of these products offered from the far east and eastern Europe offer a nice alternative for a fun project. You get something that already works and you can enjoy it out of the box and then you can pick people's brains in a place like this to figure out ways to make it better. It's almost like a prebuilt kit that provides a fertile platform for experimentation. Even better, you can usually do it for cheap.
Anyway, I've enjoyed reading the comments and I do have to say, at least fit and finish wise I think my very limited funds will probably still find their way to the Chinese but I still like seeing offerings like this from other places. More options are always better for everyone but it still takes the wisdom of some of the more senior folks here to not truly waste your money. For example, I never thought to think that those light bulbs are not going to be easy to find outside of the country of origin... Good point!
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OK...we've all picked apart this amp for what it is and what it is not. The manufacturers have gone to the extreme to market this abomination with any and all "parts" to make this thing function. "I need two hundred tuna cans, right now....empty!" Someone went thru the available parts in-house & this is what they came up with. It really can't be used as a base for a DIYer for mods as the chassis is unusably small.....the "OPTs" have to be dumped...the MOST expensive part.
It all boils down to how cheap can you make it & how much can you sell it for.
Throw in some choice ** text praising your own creation & hope your prospective customer has just enough but not too much knowledge about tube amps.
____________________________________________________Rick...........
It all boils down to how cheap can you make it & how much can you sell it for.
Throw in some choice ** text praising your own creation & hope your prospective customer has just enough but not too much knowledge about tube amps.
____________________________________________________Rick...........
The funny thing about this story is that an average DIYer could design something better than this. It is always good to remember that the only difference between an amateur and a professional is money, not competence.
Some people do seem to have made good amps by buying Chinese dross off ebay then rebuilding them. The curious thing is that in many cases the correct design would not have been much more expensive to sell than the rubbish. This could mean that the original sellers weren't being dishonest, but merely stupid.
It does make life hard for the normal consumer. How can he tell which shiny amp has good design and safe construction? One thing to remember is that every dollar spent on appearance is a dollar not spent on sound or safety!
Some people do seem to have made good amps by buying Chinese dross off ebay then rebuilding them. The curious thing is that in many cases the correct design would not have been much more expensive to sell than the rubbish. This could mean that the original sellers weren't being dishonest, but merely stupid.
It does make life hard for the normal consumer. How can he tell which shiny amp has good design and safe construction? One thing to remember is that every dollar spent on appearance is a dollar not spent on sound or safety!
I sorry about this above. I opened a discussion on another site but got no tech response, so I had to post the same thread here to get some expert help.
Regards, Gustavo
P.S.: I want to thank all the posters for their valuable help in this thread. Thumbs-up.
Hi, there.
I am "Mr Vetruvio" or, if you prefere, Ciro Cravetto from Italy. The disigner of this amp.
1) There is written nowhere that the schematic visible on my site is the same there is inside the amp.
2)Here you can find the very basic schematic of the amp actually for sale. The amp is a circlotron in S.E.: the bulb on the other side works as a constant current generator and allows to achieve a perfect output offset without any continuous current in the primary winding of the the output transformer. It means that there's no need of any output capacitor.
3) Yes, it true: this design allows to save some money
4) No chinese is doing something like this.
5) The output power is 29 Watts RMS!!!
6) The boxes where I placed the output transformers are not for tuna, but for meat and they are perfect for to resin inside the trasformers. Any way they are painted.
7) Output transformers are toroid and they are made by me as well as the power ones and as well as the case.
8) This forum is a "scientific society", so I am sure that you will be able to find out a driver of this output stage. I did not published because probably you will do a better job.
Good luck, Ciro Cravetto
I am "Mr Vetruvio" or, if you prefere, Ciro Cravetto from Italy. The disigner of this amp.
1) There is written nowhere that the schematic visible on my site is the same there is inside the amp.
2)Here you can find the very basic schematic of the amp actually for sale. The amp is a circlotron in S.E.: the bulb on the other side works as a constant current generator and allows to achieve a perfect output offset without any continuous current in the primary winding of the the output transformer. It means that there's no need of any output capacitor.
3) Yes, it true: this design allows to save some money
4) No chinese is doing something like this.
5) The output power is 29 Watts RMS!!!
6) The boxes where I placed the output transformers are not for tuna, but for meat and they are perfect for to resin inside the trasformers. Any way they are painted.
7) Output transformers are toroid and they are made by me as well as the power ones and as well as the case.
8) This forum is a "scientific society", so I am sure that you will be able to find out a driver of this output stage. I did not published because probably you will do a better job.
Good luck, Ciro Cravetto
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