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Old 18th April 2013, 07:17 PM   #1891
Siberia is offline Siberia  Lithuania
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Quote:
Originally Posted by Salas View Post
The 118 is notched for THD measurements and FFT analysis, 0.0015% 200Hz-10kHz. Sinewave output only probably. The Instek is to see wiggles and rise times and HF frequency limit. First is up to 200kHz only, the other one is 3MHZ. C1-93 that Stajo has and other stuff were done in Vilnius and Minsk back in the day so there may be interesting NOS around in your area. Soviet stuff used some weird BNC like but not exactly BNC fitting some times, so watch that also.
Thank you. I'm one step from Instek $.
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Old 18th April 2013, 09:12 PM   #1892
Salas is offline Salas  Greece
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Originally Posted by stajo View Post
I will take it in stages to see what I will find out. I worked on shielding today but I didnt get it to a listening ready state beforeI had to move over to a mandatory beershooting/pooldrinking activity with workbuddies. More story tomorrow maybe
OK but mine is the bootstrapped one with Teflon cap on input also keep in mind.
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Old 18th April 2013, 09:18 PM   #1893
Salas is offline Salas  Greece
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Originally Posted by Siberia View Post
Thank you. I'm one step from Instek $.
For general use function generator you seldom get less than -55dBc distortion. Those equipment are not specialized for THD measurements. They are to feed many waveform types over a large bandwidth so to monitor the time domain. Many budget to enough hundred $ DDS have jitter especially in the kHz. That Siglent double output with impressive features, color menu screen and extended bandwidth many got to regret for instance. The squares were dancing the lower they went in frequency. LeCroy sells it over 1000$ in base model black color with its badge on...That Instek is dependable and I say so bcs I had used it.
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Old 18th April 2013, 10:23 PM   #1894
stajo is offline stajo  Sweden
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We're only in it for the drugs, as a friend of mine put it while intervued by the press about latest album. The instruments, who cares. Im guilty I know.
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Old 18th April 2013, 10:30 PM   #1895
tinitus is offline tinitus  Europe
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Originally Posted by buzzforb View Post
For driving balanced amp.
how about using a simple split load phase splitter
(I have seen one converting SE signal to balanced with a jfet or BJT)
and its so simple you can mount it directly on the XLR plug
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Old 18th April 2013, 11:41 PM   #1896
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Gonna stick to Original Salas 6V6. Its worth it. I can either feed amp SE or build different pre. This one is a keeper and I will see it finished properly.
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Old 19th April 2013, 12:37 AM   #1897
6L6 is offline 6L6  United States
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Buzz - With or without shunt regs?
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Old 19th April 2013, 12:43 AM   #1898
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First one had dual SSHV(mine).New will have the same. Adding choke to psu. Mainly rebuilding because of PSU and to use official SsHV vs my homegrown boards. Itwas good enough that i dropped nice coon on NOS 6V6GTA .
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Old 19th April 2013, 03:47 PM   #1899
stajo is offline stajo  Sweden
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A chief developer and good friend of mine once told me "-A fool with a tool is just a bigger fool" when I installed some version of Visual Studio to play with. He was ofc right in that and it is definately an expression that describes me well atm.

A week or two ago and some 100ish posts away I was concerned with a "B+ ripple" that later showed to be unexisting. I had hum in the speakers, the DMM and my lousy scope pointed on that.

After using a proper scope I could conclude that its not in B+, its rather in filaments or in EMI. Trying an extremely overkilled LM350 reg on the filaments took hum down to listenable levels but not to a level that makes measurements justice.

I now used a passively filtered DC arrangement with uV ripple and hum went up again to audiable levels in the sofa. The cathode choked 6V6 starts to act like an extremely sensitive DHT with microphonics and I think I would need something like a Coleman reg to solve this, and I dont have any. I have a bunch of 3,5 kg 170ish mH 1,5 ohm chokes in the 3 amp region that might take care of that but I'm not in the mood to try that.

Well. Still confused but on a higher level and hungover too. Shall we try a choke loaded anode follower maybe? I think I can get some 280ish B+ in this config with SSHVs.

Last edited by stajo; 19th April 2013 at 03:52 PM.
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Old 19th April 2013, 04:37 PM   #1900
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I have a 6V6 pre running basic setup with just current regulated heaters and it works perfectly.

Indirekt heated tubes arenīt to fuzzy about the heating supply.

I usually split the contraption thatīs making my life miserable and put the individual PSUīs a bit apart and then start investigating whatīs the source of the problem.

Wound components has a bad habit of both sending and receiving a lot of unwanted stuff so just moving things around can sometimes solve it.
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