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Old 23rd June 2008, 06:27 AM   #2101
reshippie is offline reshippie  United States
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Quote:
Originally posted by alexg
My new 12au7 cathode follower preamp. Tube rectified, tube regulated PSU, I use one 12au7 for the voltage amp for both channels and another 12au7 for the cathode follower stage, it gives me better tube rolling options!

Do you have a schematic available? I'm planning on starting a 12au7 preamp, or maybe something between that and 12ax7, soon but I haven't decided on a design. Will be my first tube project so I'd like to use a design that's already been vetted.
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Old 23rd June 2008, 10:42 PM   #2102
tomsyl is offline tomsyl  United States
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Default A (belated) reply to cycline3's post #2080

A wise man once said that you can either remain silent and risk people thinking you are ignorant, or open your mouth and prove it. You chose the latter with your post.

Instead of your strange, disjointed rant about me being a " n00b" who works in Wendy's, you might have just asked how the 6kOhm primary impedance of the OPTs was selected. I looked at a number of established 300B PP designs, of which two stood out. One was Lynn Olson's meticulously documented Aurora amps; he uses custom-wound 6.6kOhm OPTs. You know all about those amps, their evolution and Olson's reputation in general, right? I ask because I noticed that despite all the wind you generated, you never said what you believe is the correct OPT primary impedance for 300Bs operated in PP Class A. Could it be that you don't know?


Another highly regarded design is the one by Kevin Kennedy that was published in Vacuum Tube Valley; he used Citation II OPTs (4.4 K) and recommended Bertolucci 123s (4K) as alternatives. Other designs centered on 6kOhms primary impedance on the basis that is was twice what typically would be used with a single 300B operating in SE. I'm sure you know Kennedy's work thoroughly, and have carefully followed his reasoning w/r/t 300B PP output stages, correct? Good; then you can explain why an OPT with three times the impedance he used would be appropriate here.

You didn't bother asking anything about where the transformers were wound, either. Jack Elliano of ElectraPrint made the final choice on primary impedance before he wound the OPTs. A super-experienced tube whiz like you must know that company well; I am certain that Jack has forgotten more about tubes in general, and transformers in particular, than you likely will ever know.

The main purpose of my post was to ask for the reasoning behind selecting 12K as a primary impedance, something I've never seen before in any published schematic. You were too busy ridiculing me and my post to answer that question, most probably because you don't even know the answer.

This usually is a very congenial place, with content-free sniveling like yours a rarity. But your peculiar and condescending rant demanded an appropriate response.
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Old 25th June 2008, 09:44 PM   #2103
dubdub is offline dubdub  United Kingdom
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where are the pics of amps peeps have built????
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Old 29th June 2008, 03:56 AM   #2104
Davec113 is offline Davec113  United States
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A few pics of the SimpleSE I just finished. It uses a ccs-loaded ecc99 driver tube and is a straight power amp. I don't think the ecc99 needs the CCS, but it was part of the circuit with the 12at7 so I thought I'd give it a try with CCS. I increased the current that the ccs supplies to just over 20 mA to better suit the ecc99 and left out the volume pot, other than that its a regular SimpleSE. It also has switches for cfb and ul operation. Some of the parts I used are Tung Sol 6550 power tubes, James OPTs, Electraprint custom choke, Riken, Kiwame and AN resistors, Mundorf SOI coupling caps and Vampire connectors. I wired it with mil spec silver plated teflon wire and Jupiter silver wire for the inputs.

I'm very happy with it so far, its powering Omega XRS speakers (these are fantastic speakers!), an Anthem Pre1 Preamp and Audio Alchemy reclocker/dac combo are upstream. Its replacing a Trends T-amp and so far is a great improvement. There is a slight ground loop hum that I need to figure out how to get rid of....

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Old 29th June 2008, 06:13 AM   #2105
chrish is offline chrish  Australia
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Nice chassis work Davec. Any particular reason for using the ECC99 rather than the ECC81?

Cheers,

Chris
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Old 29th June 2008, 07:19 AM   #2106
Davec113 is offline Davec113  United States
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Quote:
Originally posted by chrish
Nice chassis work Davec. Any particular reason for using the ECC99 rather than the ECC81?

Cheers,

Chris

Thanks, the ecc99 has lower mu than the ecc81, and my preamp has quite a bit of gain. Another guy living near me has a SimpleSE with the ecc81 driver and most of the same parts I used, so I should get a chance to compare them. Also, the ecc99 looked like it would be more linear than the eccec81, which is why i think ccs loading might not be needed (and also since I don't need more gain).

Also, I got rid of the ground loop hum by connecting the chassis of the preamp to the amp with a 12g wire... I'm guessing this is ok?
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Old 29th June 2008, 07:33 AM   #2107
alexg is offline alexg  Philippines
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Default Re: A (belated) reply to cycline3's post #2080

Quote:
Originally posted by tomsyl
A wise man once said that you can either remain silent and risk people thinking you are ignorant, or open your mouth and prove it. You chose the latter with your post.

Instead of your strange, disjointed rant about me being a " n00b" who works in Wendy's, you might have just asked how the 6kOhm primary impedance of the OPTs was selected. I looked at a number of established 300B PP designs, of which two stood out. One was Lynn Olson's meticulously documented Aurora amps; he uses custom-wound 6.6kOhm OPTs. You know all about those amps, their evolution and Olson's reputation in general, right? I ask because I noticed that despite all the wind you generated, you never said what you believe is the correct OPT primary impedance for 300Bs operated in PP Class A. Could it be that you don't know?


Another highly regarded design is the one by Kevin Kennedy that was published in Vacuum Tube Valley; he used Citation II OPTs (4.4 K) and recommended Bertolucci 123s (4K) as alternatives. Other designs centered on 6kOhms primary impedance on the basis that is was twice what typically would be used with a single 300B operating in SE. I'm sure you know Kennedy's work thoroughly, and have carefully followed his reasoning w/r/t 300B PP output stages, correct? Good; then you can explain why an OPT with three times the impedance he used would be appropriate here.

You didn't bother asking anything about where the transformers were wound, either. Jack Elliano of ElectraPrint made the final choice on primary impedance before he wound the OPTs. A super-experienced tube whiz like you must know that company well; I am certain that Jack has forgotten more about tubes in general, and transformers in particular, than you likely will ever know.

The main purpose of my post was to ask for the reasoning behind selecting 12K as a primary impedance, something I've never seen before in any published schematic. You were too busy ridiculing me and my post to answer that question, most probably because you don't even know the answer.

This usually is a very congenial place, with content-free sniveling like yours a rarity. But your peculiar and condescending rant demanded an appropriate response.
I full agree with you.

Am a "nOOb", I ask newbie questions, but I don't work for Wendy's!

I am in this forum to learn and contribute what I learned.
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Old 29th June 2008, 08:24 PM   #2108
resr is offline resr  Estonia
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my unfinished project:
http://nagi.ee/photos/ResR/6385159/
Tubes have connected only heating elements with scrapped tube-tv transformerĀLs 6,3V secondary. Except the scrapped 6E1ĄP, it has a anode voltage directly from 230V through recitifier, what consist two scrapped 6X1ĄP and old capacitors. One 6E1ĄP donĀLt work well and i donĀLt have enough money to buy new ones.
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Old 29th June 2008, 08:34 PM   #2109
Milen is offline Milen  Bulgaria
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resr, nice work! Is the big tube in the mid GP-5 ?
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Old 29th June 2008, 09:18 PM   #2110
SpreadSpectrum is offline SpreadSpectrum  United States
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Quote:
..but I don't work for Wendy's
Even if you did, that wouldn't be an excuse for the rudeness.
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