Forums
New posts
Search forums
What's new
New posts
Latest activity
Members
Registered members
Current visitors
Log in
Register
What's new
Search
Search
Search titles only
By:
New posts
Search forums
Menu
Log in
Register
Install the app
Install
Audio and Video Talk
Valves / Vacuum Tubes
Ideas for MM valve phonostage
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Reply to thread
Help Support AVForums:
This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Message
<blockquote data-quote="Ampdog" data-source="post: 955370" data-attributes="member: 144"><p>Night thoughts at this time:</p><p></p><p> </p><p></p><p>Missing something here. . .</p><p></p><p>"Berclowe 3" ? Is one of the circuits shown here that of the Berclowe 3? (er - not noticed in the middle of night -) You mean?</p><p></p><p>As to valves: I would look at ECC88s or equivalents. ECC81 is also suitable, but being mainly intended for r.f., they can be microphonic. (Again, valve ? also features in the cathode follower output impedance, and the 12AX7 simply does not cut it. Funny: While the 12AX7 is a low-noise triode(s) particularly intended for audio, I hardly ever find it the most suitable for any audio application. But that's just me . . .) </p><p></p><p>Then in certain quarters there also seems to be a preference for EF86 triode-connected. Not in this household I fear; not compared to the previously mentioned low noise 6GK5/6FQ5A (? = 78; gm = a whopping 15K ?mhos, albeit at a high Ia.) And it is a frame-grid valve - to be preferred for mechanical stability.) </p><p></p><p>Another point raised earlier by someone: No, no difference in separating the two parts of an RIAA filter; the h.f. part can simply come in parallel with R7-R8. Different values obviously. </p><p></p><p>Caveat: I have not at this time looked at the neatly columned component values given. Further explanations next time.</p></blockquote><p></p>
[QUOTE="Ampdog, post: 955370, member: 144"] Night thoughts at this time: Missing something here. . . "Berclowe 3" ? Is one of the circuits shown here that of the Berclowe 3? (er - not noticed in the middle of night -) You mean? As to valves: I would look at ECC88s or equivalents. ECC81 is also suitable, but being mainly intended for r.f., they can be microphonic. (Again, valve ? also features in the cathode follower output impedance, and the 12AX7 simply does not cut it. Funny: While the 12AX7 is a low-noise triode(s) particularly intended for audio, I hardly ever find it the most suitable for any audio application. But that's just me . . .) Then in certain quarters there also seems to be a preference for EF86 triode-connected. Not in this household I fear; not compared to the previously mentioned low noise 6GK5/6FQ5A (? = 78; gm = a whopping 15K ?mhos, albeit at a high Ia.) And it is a frame-grid valve - to be preferred for mechanical stability.) Another point raised earlier by someone: No, no difference in separating the two parts of an RIAA filter; the h.f. part can simply come in parallel with R7-R8. Different values obviously. Caveat: I have not at this time looked at the neatly columned component values given. Further explanations next time. [/QUOTE]
Insert quotes…
Verification
Post reply
Audio and Video Talk
Valves / Vacuum Tubes
Ideas for MM valve phonostage
Top