Home » Audio » Group Build » Low Cost Phono Preamp for MM and LOMC
Low Cost Phono Preamp for MM and LOMC [message #77471] Sat, 10 August 2013 22:26 Go to next message
gofar99 is currently offline  gofar99
Messages: 1443
Registered: May 2010
Location: Southern Arizona
Illuminati (3rd Degree)
Hi Everyone, To do some low noise testing I needed to build a solid state phono preamp. The results exceeded my expectations sufficiently that I wrote it up for diyers. So here it is....




Good Listening
Bruce
Re: Low Cost Phono Preamp for MM and LOMC [message #77472 is a reply to message #77471] Sun, 11 August 2013 10:25 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 17463
Registered: January 2001
Illuminati (33rd Degree)

Bruce, that's awesome. Thanks for posting the design here!

I really like that op amp, and I think I'll give this circuit a try.

Thanks again!

Re: Low Cost Phono Preamp for MM and LOMC [message #77473 is a reply to message #77472] Sun, 11 August 2013 11:25 Go to previous messageGo to next message
gofar99 is currently offline  gofar99
Messages: 1443
Registered: May 2010
Location: Southern Arizona
Illuminati (3rd Degree)
Hi Everyone, This is an easy build and very nice sounding. I listened to it again today and it is better than the SS one I use for comparison (a Simaudio Moon LP3). The sound is not as clinical as the Moon. It is warmer and smoother at least in my system. I believe the LP3 has an edge on S/N but then it is the quietest device I have ever run into with a S/N on MM of -106 dbv and -90 on LOMC. This one is the same for LOMC, but not that quiet for MM. As FYI, anything over about -80 dbv is so quiet in an audio system that the background noise in the listening room will be far higher. I design for a minimum of -90 in all my projects as that gives a really comfortable margin.

Good Listening
Bruce
Re: Low Cost Phono Preamp for MM and LOMC [message #78337 is a reply to message #77473] Sun, 10 November 2013 17:08 Go to previous messageGo to next message
gofar99 is currently offline  gofar99
Messages: 1443
Registered: May 2010
Location: Southern Arizona
Illuminati (3rd Degree)
Hi Everyone, an update. I attached a revised schematic. One small change for gain (300R vs 330R) but the thing can do NAB tape playback if you have a reel to reel player now as well.
index.php?t=getfile&id=1340&private=0


Good Listening
Bruce
Re: Low Cost Phono Preamp for MM and LOMC [message #78338 is a reply to message #78337] Mon, 11 November 2013 08:43 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 17463
Registered: January 2001
Illuminati (33rd Degree)

Oh, dude, that's awesome. Thanks!

Re: Low Cost Phono Preamp for MM and LOMC [message #78356 is a reply to message #78338] Tue, 12 November 2013 21:45 Go to previous messageGo to next message
gofar99 is currently offline  gofar99
Messages: 1443
Registered: May 2010
Location: Southern Arizona
Illuminati (3rd Degree)
Hi, As promised....it works great. Low noise, clean sound and sufficient gain. Either the high or low gain can be used and it seems to work best into the 47K load.

Good Listening
Bruce
Re: Low Cost Phono Preamp for MM and LOMC [message #78401 is a reply to message #77471] Mon, 18 November 2013 13:11 Go to previous messageGo to next message
Nico is currently offline  Nico
Messages: 15
Registered: November 2013
Chancellor
These look at interesting schematics. I've been looking for some ideas for my next project and it looks like I've found it. I'll let you know how it turns out.
Re: Low Cost Phono Preamp for MM and LOMC [message #78609 is a reply to message #78401] Tue, 10 December 2013 21:19 Go to previous messageGo to next message
gofar99 is currently offline  gofar99
Messages: 1443
Registered: May 2010
Location: Southern Arizona
Illuminati (3rd Degree)
Hi, I don't know if this should be here or in source with the reel to reel recorder....anyhow I rewired the tape recorder (yes I know it was really nice and new to me only about two weeks ago). The change was to make it possible to send the output from the tape play back heads to an external preamp...yup the one that was the subject of this thread. I can switch from internal preamps to external now.

This was a major improvement in an already good machine. The S/N is about 6 db better and the sound is every bit as good or perhaps even better than before. I used the high gain setting, NAB equalization and 47K input loading. Works great. A really worthy upgrade to most any recorder.



Good Listening
Bruce
Re: Low Cost Phono Preamp for MM and LOMC [message #78612 is a reply to message #78609] Wed, 11 December 2013 10:58 Go to previous message
Wayne Parham is currently offline  Wayne Parham
Messages: 17463
Registered: January 2001
Illuminati (33rd Degree)

I've been really busy this season, but as soon as the dust settles, I really want to build one up and try this out.

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