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Old 1st January 2005, 10:35 PM   #101
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RDH4 was on Greg's (geek's) website somewhere. For some reason I can't find it now. When I do, I'll post the url.

EDIT: I feel like an idiot ... It was on the front page of his website. Here is a link

Thanks to Greg (Geek), Tim (Sch3mat1c) and Chocky (?) for making this happen

They need mirrors desperately to share the load around (the entire book is around 77MB), so anyone with spare webspace and bandwidth...
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Old 2nd January 2005, 07:42 AM   #102
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Default Re: EF86

Quote:
Originally posted by chrisb
Alex, I hope my last post didn't sound petulant - that was not my intention.


While I'm at it, I should mention that the next scheduled revision is to change the input tube to an EF86 (once again courtesy of my "mystery" benefactor) Since I've got another 3 day weekend, I'll probably implement that before your reply.

cheers y'all


Well Dave, even tho I got a late start this evening, I did manage to get the EF86's installed - may need to add a little attenuation - rather a lot of gain. Also eliminated the last RC filter stage per Eddie's suggestion, perhaps prematurely; along with the intense gain we got some Lou back. I'll report further after a few hours of music. so far sounds promising. maybe I should stop now

"what, you're 'sposed to listen to them? Then how can you tell how good they are, if you're not comparing notes with the other geeks?


good night all
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Old 2nd January 2005, 07:59 AM   #103
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Default Re: Re: EF86

Quote:
Originally posted by chrisb
along with the intense gain we got some Lou back.
:^(

dave
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Old 2nd January 2005, 08:14 AM   #104
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Hi,

Quote:
along with the intense gain we got some Lou back.
Reed?


Cheers,
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Old 2nd January 2005, 08:28 AM   #105
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Quote:
Originally posted by fdegrove
Reed?
No... an inside joke. The Professor has a bit much in the hubris department. His breadboard system with some 80 pieces of iron tends to HUM....

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Old 2nd January 2005, 08:35 AM   #106
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Hi,

Quote:
His breadboard system with some 80 pieces of iron tends to HUM....
LOL....Inductive coupling from BC to LOUisiana, he?

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Old 2nd January 2005, 08:39 AM   #107
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Quote:
Originally posted by fdegrove
LOL....Inductive coupling from BC to LOUisiana, he?
More like from BS...

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Old 5th January 2005, 10:36 AM   #108
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Default LOTS OF THINGS TO DO...

Hi to all,
I missed the forum the last couple of days -- I have not even had the chance to go online.

First of all, I would like to comment on the RDH4 -- when I read that "we'll end up with RH" I got very interested, since I've never heard of the RDH4, and never read it, of course. But, what I saw was but a general schematics -- now it remains to be read (when I find it online) whether there is some concrete explanation how to do it. But I fear not, since it will most probably just address the feedback to be applied between anodes etc. So, for as much as I'm concerned, that is just another interesting text from the times of old when tubes glowed bold.

Furthermore, the RH6550 is slowly making progress... now the rectifier is an AX50, giving it the best sound yet. But, it is not the mercury vapor rectifier that is blessed with good sound -- I recon that is more about the fact that 6550, KT88, KT90 (Ei) are "ugly brutes" that should not be treated kindly. Insertion of the AX50 has risen the B+ to a value where there is 400V across the output tube and some 110mA drawn by the cathode... consequently, the dissipation is now reaching max. values - and the sound is improving (mostly) because of that -- although the output transformer arrangement that it has (momentarily) to work with is to say the least "ridiculous". Great bass, too.

Well, the schematics for RH2G is more resemblant to the mentioned John Broskie article. But, with all due respect to Mr. Broskie, and all other people who have contributed to tube design in the previous century I feel the need to give myself a little credit -- I'm self taught, meaning that I have no formal electronics training (economist and scientifical-technical translator). Therefore, I had to learn all that I know by reading and thinking... without direct tutors or anything. Furthermore, when someone writes a teoretical article on his idea, or whatever (i.e. some notion from an old and forgotten textbook) -- that is one pair of shoes. Implementing it in practice, knowing what and why to do in order to find the right values -- that is a different pair of shoes. At least to me. And should deserve some credit.

Finally, about the EF86 implementation: well, I have previously mentioned that instead of the ECC81 driver ECC83 could be directly substituted, with the previously mentioned consequences etc. BUT, substituting one tube for another is not necessarily leading to better results, no matter what the teory might imply. Unless these results are "above the theoretical plane" meaning that i.e. using a pentode (higher output impedance) current "source" might lead to better sound or something. Furthermore, just substituting anything for whatever, without further substitution of circuit parts is not necessarily a good option.

That's it for now... Actually, posting on the forum regularly is a bit difficult for me, because unlike most of you (I presume) I do not have ADSL or whatever 24hrs online access, but a mere dial-up, further worsened by years of monopoly in the state where I live (meaning that both telecommunications provider and internet provider are far from being good... and face no real competition, either because of signed agreements with the government (!) or because they where there first and now there is noone with enough starting capital to be able to surpass them on a massive scale...) -- therefore writing posts regularly is to say the least "challenging". So, feel free to contact me via e-mail.

Regards,
Aleksandar
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Old 5th January 2005, 11:22 AM   #109
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Default Re: LOTS OF THINGS TO DO...

Quote:
Originally posted by Alex Kitic
Hi to all,
I missed the forum the last couple of days -- I have not even had the chance to go online.
The forum went offline till a few hours ago, so you didn't miss anything

Quote:
Originally posted by Alex Kitic
So, for as much as I'm concerned, that is just another interesting text from the times of old when tubes glowed bold.
The RDH4 was, and still is the most respected text for general information about valves and valve circuits. It is well worth a read.

I also read somewhere that this sort of plate-to-plate feedback was popular in the output stages of antique radios.

Quote:
Originally posted by Alex Kitic
I feel the need to give myself a little credit -- I'm self taught, meaning that I have no formal electronics training (economist and scientifical-technical translator). Therefore, I had to learn all that I know by reading and thinking... without direct tutors or anything.
Same here. Completely self-taught..... So I come up with ideas which I think are original, only to find someone else beat me to it fifty years ago. Such is life. But it doesn't matter if it's been thought of before, it was an original idea to you and that is what matters (along with good music )

Quote:
Originally posted by Alex Kitic
Actually, posting on the forum regularly is a bit difficult for me, because unlike most of you (I presume) I do not have ADSL or whatever 24hrs online access, but a mere dial-up, further worsened by years of monopoly in the state where I live (meaning that both telecommunications provider and internet provider are far from being good... and face no real competition, either because of signed agreements with the government (!) or because they where there first and now there is noone with enough starting capital to be able to surpass them on a massive scale...) -- therefore writing posts regularly is to say the least "challenging". So, feel free to contact me via e-mail.
Alex, you're not alone. I am on dial-up too.... the 'horse and cart' version of the internet - or maybe I should say the valve version? (well they're both obsolete technologies). It took me about ten hours to download the RDH4.
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Old 5th January 2005, 02:18 PM   #110
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Default Re: LOTS OF THINGS TO DO...

Quote:
Originally posted by Alex Kitic
Hi to all,
I missed the forum the last couple of days -- I have not even had the chance to go online.

First of all, I would like to comment on the RDH4 -- when I read that "we'll end up with RH" I got very interested, since I've never heard of the RDH4, and never read it, of course. But, what I saw was but a general schematics -- now it remains to be read (when I find it online) whether there is some concrete explanation how to do it. But I fear not, since it will most probably just address the feedback to be applied between anodes etc. So, for as much as I'm concerned, that is just another interesting text from the times of old when tubes glowed bold.



Regards,
Aleksandar

send me a mail to my private addy (you know it) and I'll send ya RDH4 on CD
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