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In Reply to: RE: Poor Design for a Preamp posted by mwhouston on February 26, 2025 at 17:55:07:
"Tre made the suggestion to use 68k+22k resistors to give me a dropping output level but not to limit upper frequency."
Actually, I was the one who suggested using the combination of 68k in series and 22k to ground and said it should improve the -3db point of the upper frequencies.
My earlier post: "OK, so in the case of this 01A preamp, he could use a voltage divider with 68k in series and 22k to ground. This would reduce the voltage about the same as the 330k/100k combo he's using and it would present a load of 90k to the tube and be no problem.
The value of 68k || 22k is 16.62k. If we plug that into the low pass calculator then the -3db point would be 54.75k. That should also not be an issue, right?"
Tre quoted me and commented about the corresponding -1db point, which he said would be 27.375kHz. He suggested that, from a technical standpoint, this would still not be enough to "get the filter completely out of the audio band".
I'm glad to hear that, from a practical standpoint, it seems like it improved things subjectively. I try to understand the technical end of things - hence my questions in this thread - but I'm not convinced that striving for technical perfection is always audible beyond a certain point. Sometimes "better than it was" is good enough and going to more extreme lengths is just a waste of time and money if it doesn't yield audible improvement. IMO, but that's just me.
I guess for an engineer technical perfection IS the goal so it's a valid pursuit regardless of whether it's audible or not.
I understand how it's easy to get confused though. AA's software is ridiculously out of date and totally lame. Unlike other sites like DIY Audio, Audio Karma, and others AA doesn't allow you to easily quote a previous post without rewriting it and adding quotation marks. As I have done above.
Unless someone makes the effort and adds a quote manually it's often impossible to tell which previous post someone is responding to.
I suspect that AA will never modernize their software. I don't know about the site as a whole but the forums I used to visit regularly years ago are pretty much dead in the water now. Some of them now go weeks without a post where, in the past, there were a large number of new posts and threads every day. Sad.
I still find some useful and interesting posts on AA but I rarely post here anymore because of the lack of activity. Fortunately, the search function yields a wealth of information from the time when AA was a vibrant forum.
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Follow Ups
- Confusion - FlaCharlie 09:50:01 02/27/25 (1)
- RE: Confusion - mwhouston 14:08:29 02/27/25 (0)
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