Originally Posted by
montesquieu
Jez I have no desire to have a big public fight with you - I respect your work and enjoy your contributions here.
But - I told you I was looking to do something on the cheap to prove the idea. I had a bad feeling about spending £300 here, and if it turns out the bulk of the the £300 was in building a gainclone then I certainly made the right decision. Though to be fair, perhaps I should have contacted you to tell you what I was doing and why. I'm certainly sorry now I didn't
I went on to ebay immediately after that email on the 11th to look at boards and mains transformers - only to find I could thanks to the miracle of chifi I could get a fully built up device for not much more. (About $80, and customs only charged me £3 for some reason).
As I say I planned to come back to you about the autoformers (not really understanding what they would add in this scenario). I'm still up for that if it makes sense.
But your IP - buying a gainclone? Come on.
I have no particular desire for a "big public fight" with you either and also enjoy your contributions to AOS but felt that something had to be said here. I certainly would not have thought you the type to do as you have....
At least half of the fee would have been in designing, building and testing the custom made auto transformers. They would then have needed testing in conjunction with the gain clone and the tweeters and any snubber networks etc found necessary (to suppress likely ringing etc) would have to be experimentally arrived at and added. Like I said, it is less straightforward than it appears. The points made by Andrew above are also most pertinent to this...
"But your IP - buying a gainclone? Come on." You were planning on obtaining the batpures and just connecting them across the outputs of your Radford power amp, sans transformer... I came up with the whole idea of using a separate amplifier to prevent the capacitive, and probably very low impedance loading at HF, from spoiling the top end from your Radford, as heard through the Tannoys own tweeters. I pointed out that a step up transformer would almost certainly be required. I said that a volume control on the extra amp would allow the super tweeter level to be set appropriately to match the Tannoy's. I advised that no you couldn't use the class D amps you had already and advised a specific gain clone type amp which I considered most suitable for the task, even going to the lengths of providing a link to a suitable board on ebay... and then gave you the specs for a suitable transformer.
Other than the autotransformers, which no doubt are built in to the factory version you bought second-hand, you followed all my technical proposals in carrying out the job yourself. Yeah that "IP".
I'm not about to take this any further or to put you on my ignore list or anything of the sort but to say I'm disappointed is putting it mildly... I would certainly think twice before doing any work for you in the future, not without guarantees that you were not going to use my answers to the questions on the lines of "and how do you propose to overcome this or that issue Jez in building this "thing" for me?" and then using the advice to either do the work yourself or get a mate to put into action or buy similar from China....
To someone who can afford the sort of hi fi gear you own, not to mention vintage harpsichords etc, I guess £300 isn't really much... It's a lot to me and I now know how a hi fi dealer who has gone to the lengths of a home demo etc must feel when the "customer" then buys it secondhand or from Amazon etc...
There is a possible issue with the bought in version of the gain clone which may make it less proficient than you would have hoped for in its standard form and which I would have remedied in my application of it.... I think I'll keep the details to myself....
Edit for your edit....
"I genuinely though re-using casework would help, it's a small case with switches, RCAs etc in place- it appeared to me that to swap out a ready-populated chip amp board for another one and swap the transformer was a half hour job"
More like 4-6 hours+ in all including safely removing all the old gubbins for re-use, measuring up, marking out and drilling new mounting holes for the board and for mounting the chip packages to the heatsink with new insulating pads etc and then testing it etc... More if there were any problems and it went less than 100% smoothly.
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