splatt Posted July 27, 2020 Posted July 27, 2020 Hi all, As I have my small amp up and running quite well and some have asked as to the next project, a pre amp for a turntable is now on the list. There are a few kits and straight up, thanks but no, not for me. If someone has a schematic of an amp they are happy with and ok to share, pass it on. My skills are limited to the next bit of special smoke escaping so I am not afraid to go hard. Maybe an area for the tube lovers to teach me on the why fors and also where to get the bits. Or do I design my own with my limited memory and reply back in 18 months...
Batty Posted July 27, 2020 Posted July 27, 2020 Have a look at this, see if it suits you. https://www.passdiy.com/project/preamplifiers/pearl-2 Thinking about it myself actually. 2
Volunteer sir sanders zingmore Posted July 27, 2020 Volunteer Posted July 27, 2020 I think @catman and @andyr are the resident experts on building phono stages (apologies to anyone else I've left out) BTW @splatt, you should probably change your thread title to make it clear you are talking specifically about phono stages as opposed to pre amps in general- you'll get more relevant views that way 3
andyr Posted July 28, 2020 Posted July 28, 2020 2 hours ago, sir sanders zingmore said: BTW @splatt, you should probably change your thread title to make it clear you are talking specifically about phono stages as opposed to pre amps in general- you'll get more relevant views that way As Trevor says, @splatt. A 'preamp' is a device which sits in front of (ie. "pre") the power amp. It's purpose is to provide source switching and volume control ... and it generally offers some gain as well. A preamp may or may not include a phono stage section - which has 2 functions: provide RIAA correction to the music signal coming from the grooves, and provide heaps of gain to boost the cart's output up to 'line levels'. From your statement "a pre amp for a turntable ", you seem to want to build a phono stage? @catman undoubtedly has a lot of experience building different phono stage kits - so you need to wait for his input. From my PoV, I would say the Rod Elliott P06 (with matching PS) would be a good thing for you to try. Andy 3
mbz Posted July 28, 2020 Posted July 28, 2020 (edited) The Nak CA-7A(?) from vintage is well regarded. Schematic available on hfe. Considered it myself, the front end fets would pose a challenge however there are a few candidates... Edited July 28, 2020 by mbz spell 1
audiofeline Posted July 28, 2020 Posted July 28, 2020 Someone on VinylEngine was very complimentary about the JFET design riaa phono preamp, one implementation is in the Boozhound (kit). Google will show there are lots of threads on it, and other similar designs (eg. LePacific). https://boozhoundlabs.com/products/bhl-audio-jfet-phono-preamplifier-kit-2sk170-riaa Here is a valve phono project fyi (don't know if it's any good or not) http://www.audiodesignguide.com/Phono/phono.pdf 2
splatt Posted July 29, 2020 Author Posted July 29, 2020 On 28/07/2020 at 7:41 AM, sir sanders zingmore said: I think @catman and @andyr are the resident experts on building phono stages (apologies to anyone else I've left out) BTW @splatt, you should probably change your thread title to make it clear you are talking specifically about phono stages as opposed to pre amps in general- you'll get more relevant views that way Yes, thanks for the feedback. What I think and what I say and or type may confuse some along with myself. Chris 1
splatt Posted July 29, 2020 Author Posted July 29, 2020 On 28/07/2020 at 10:40 AM, andyr said: As Trevor says, @splatt. A 'preamp' is a device which sits in front of (ie. "pre") the power amp. It's purpose is to provide source switching and volume control ... and it generally offers some gain as well. A preamp may or may not include a phono stage section - which has 2 functions: provide RIAA correction to the music signal coming from the grooves, and provide heaps of gain to boost the cart's output up to 'line levels'. From your statement "a pre amp for a turntable ", you seem to want to build a phono stage? @catman undoubtedly has a lot of experience building different phono stage kits - so you need to wait for his input. From my PoV, I would say the Rod Elliott P06 (with matching PS) would be a good thing for you to try. Andy Thanks Andy. A phono stage is what I was wanting to do. I will look up the design you provided. Thanks again for your feedback. Cheers Chris
splatt Posted July 29, 2020 Author Posted July 29, 2020 On 28/07/2020 at 2:16 PM, audiofeline said: Someone on VinylEngine was very complimentary about the JFET design riaa phono preamp, one implementation is in the Boozhound (kit). Google will show there are lots of threads on it, and other similar designs (eg. LePacific). https://boozhoundlabs.com/products/bhl-audio-jfet-phono-preamplifier-kit-2sk170-riaa Here is a valve phono project fyi (don't know if it's any good or not) http://www.audiodesignguide.com/Phono/phono.pdf Certainly some great feedback on this design. Simple, effective. Thanks Chris 1
splatt Posted July 29, 2020 Author Posted July 29, 2020 On 28/07/2020 at 7:15 AM, Batty said: Have a look at this, see if it suits you. https://www.passdiy.com/project/preamplifiers/pearl-2 Thinking about it myself actually. Thanks. This also looks a great place to start. Looks like I may try a couple of designs over time. Cheers Chris
splatt Posted July 29, 2020 Author Posted July 29, 2020 On 28/07/2020 at 10:52 AM, mbz said: The Nak CA-7A(?) from vintage is well regarded. Schematic available on hfe. Considered it myself, the front end fets would pose a challenge however there are a few candidates... Hi mbz, I am not sure what hfe is to find the schematic. Thanks Chris
audiofeline Posted July 29, 2020 Posted July 29, 2020 4 hours ago, splatt said: Hi mbz, I am not sure what hfe is to find the schematic. Thanks Chris "hfe" = "Hi-Fi Engine", a website with free download (with registration) of hifi manuals, service manuals, etc. The accompanying site is Vinyl Engine, which has downloads for turntables and related (eg, carts, etc.) plus an active discussion forum.
Monkey_Relish Posted July 29, 2020 Posted July 29, 2020 (edited) I have just finished building this one :- CNC Phono Preamp (MM) This is a two stage op-amp MM preamp, with passive RIAA equalisation between the two stages. The thread is over 150 pages, a lot to read. PM sachu888 on there for PS and Phono boards. Muffsy also does a slightly modified version as well, and sells PS and Phono boards It’s a very quiet phono noise wise (I’m using a wall wart to an internal PS), very detailed and nice bass. I have a couple of recommended op-amps coming in to try, to see what difference they make. @catman has made one as well I believe. Mr Relish Edited July 29, 2020 by Monkey_Relish More info
muon* Posted July 29, 2020 Posted July 29, 2020 7 hours ago, splatt said: Certainly some great feedback on this design. Simple, effective. Thanks Chris I had one of the Boozhound kits but replaced parts with premium ones and it really lifted it to excellent sounding, Silmic ll's for power decoupling and and quality caps in the RIAA and good resistors, some were Shinkoh, I paid special attention to using the best output caps I could. Moved to a decent tube stage also with good parts and went sideways in quality rather than up.
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