catman Posted August 9, 2015 Share Posted August 9, 2015 (edited) G'day all, well it has been a somewhat interesting week and mostly because I completed successful construction of the Akitika phono stage, and whilst it is designed to be included into the larger Akitika PR-101 line preamplifier, I built the phono stage as a standalone stereo phono stage, powered by my existing DIY ESP P05B plus and minus 15 volt power supply. Interestingly enough at least according to the phono stage circuit diagram 12 volt rails are used however 15 volt rails cause no problem and actually improves signal headroom somewhat. Building this phono stage involved more assembly work than I had expected but was completed without any hassles....just a lot of soldering! Assembly aside, how does it sound? Very nice indeed. I actually did a little op amp rolling after completion and it is my feeling that whilst the supplied NE5532's work and sound fine, the substitution of these to OPA2134's results in a smoother and more musical sound without any noise penalty, (but don't ask me why....I don't know). I've actually done a head to head comparison against my DIY ESP P06 which reveals only a very subtle difference in sound quality and in fact in terms of treble 'openness' the P06 has the slight edge! However the Akitika phono stage is a lovely sounding, smooth and detailed phono stage with on board capacitance loading and useful adjustment provisions. Very neat! However the Akitika has one enormous 'plus' over the ESP P06, it is a very quiet phono stage, even at maximum gain (about the same level as the ESP P06). How I wish that my ESP P06 was as supremely quiet! The Akitika uses an interesting active Miller Loop circuit configuration to determine the (47 k) input impedance of the phono stage, suggesting a 13 db theoretical improvement in 'quietness', over the more commonly used 47 k 'termination resistor'. Whatever the reason, the Akitika phono stage is unbelievably quiet. Most impressive! The designer of this phono stage certainly knows his stuff! This is a superb DIY phono stage for moving magnet and high output moving coil phono cartridges. I love it! Regards, Felix. Edited August 9, 2015 by catman 1 Link to comment Share on other sites More sharing options...
Batty Posted August 9, 2015 Share Posted August 9, 2015 Do you have a link for the site? Link to comment Share on other sites More sharing options...
catman Posted August 9, 2015 Author Share Posted August 9, 2015 G'day mate, try here: http://www.akitika.com/PhonoPreamp.html Regards, Felix. Link to comment Share on other sites More sharing options...
Batty Posted August 9, 2015 Share Posted August 9, 2015 THanks Felix, I may give that a go. Link to comment Share on other sites More sharing options...
Batty Posted August 13, 2015 Share Posted August 13, 2015 Just ordered one. 1 Link to comment Share on other sites More sharing options...
Batty Posted October 21, 2016 Share Posted October 21, 2016 Finally got around to posting pics of the completed phono stage. 1 Link to comment Share on other sites More sharing options...
mloutfie Posted October 22, 2016 Share Posted October 22, 2016 Is 30db boost mode enough for low output MC? Link to comment Share on other sites More sharing options...
Zaphod Beeblebrox Posted October 22, 2016 Share Posted October 22, 2016 Hmmm. What regulators does it use? Here's what I suggest: * Dump the toroidal transformer and use an EI, C core or best of all, an R core transformer. *Use lots of capacitance after the rectifiers. *A capacitance multiplier after that. *Followed by LM317/337 regs. *Bypass caps at the supply pins of the OP amps. 1 Link to comment Share on other sites More sharing options...
Batty Posted October 22, 2016 Share Posted October 22, 2016 19 hours ago, mloutfie said: Is 30db boost mode enough for low output MC? Not in my system, this is a MM only stage, for MC I have a Boozehound Labs Pre pre. Link to comment Share on other sites More sharing options...
Batty Posted October 22, 2016 Share Posted October 22, 2016 15 hours ago, Zaphod Beeblebrox said: Hmmm. What regulators does it use? Here's what I suggest: * Dump the toroidal transformer and use an EI, C core or best of all, an R core transformer. *Use lots of capacitance after the rectifiers. *A capacitance multiplier after that. *Followed by LM317/337 regs. *Bypass caps at the supply pins of the OP amps. It uses 78xx and 79xx regulators, the supply is very basic to say the least, however when I built this cashflow was not very good. The supply is probably the best area to improve. Link to comment Share on other sites More sharing options...
Zaphod Beeblebrox Posted October 22, 2016 Share Posted October 22, 2016 43 minutes ago, Batty said: It uses 78xx and 79xx regulators, the supply is very basic to say the least, however when I built this cashflow was not very good. The supply is probably the best area to improve. Indeed. The M317/337 regs are a significant step up in quality. The transformer is one of the biggest problems I see. Toroidals have no place in phono preamps. 1 Link to comment Share on other sites More sharing options...
Sierra Posted October 23, 2016 Share Posted October 23, 2016 5 hours ago, Zaphod Beeblebrox said: ...... Toroidals have no place in phono preamps. Why is that Zaph? Aren't toroidal's meant to have the smallest magnetic field therefore less likely to induce 50hz hum into a delicate circuit close by? Link to comment Share on other sites More sharing options...
Zaphod Beeblebrox Posted October 23, 2016 Share Posted October 23, 2016 Just now, Sierra said: Why is that Zaph? Aren't toroidal's meant to have the smallest magnetic field therefore less likely to induce 50hz hum into a delicate circuit close by? Indeed, but they also couple VERY nicely to the mains. They have a very wide bandwidth and allow any mains bourne interference through. Obviously, the best option is an 'R' core transformer, mounted externally. Link to comment Share on other sites More sharing options...
Sierra Posted October 23, 2016 Share Posted October 23, 2016 Thanks for that explanation Zaph ... good to know ... cheers! Link to comment Share on other sites More sharing options...
PKay Posted March 17, 2017 Share Posted March 17, 2017 (edited) On 22/10/2016 at 10:45 AM, Batty said: Finally got around to posting pics of the completed phono stage. That looks like a huge amount of fiddly work. How long did it take? Edited March 17, 2017 by Nap250 Link to comment Share on other sites More sharing options...
Batty Posted March 19, 2017 Share Posted March 19, 2017 a weekend Link to comment Share on other sites More sharing options...
Ian McP Posted March 20, 2017 Share Posted March 20, 2017 Sulzer regulators and their variants are worth investigating https://tangentsoft.net/elec/opamp-linreg.html regards Ian Link to comment Share on other sites More sharing options...
Ian McP Posted March 20, 2017 Share Posted March 20, 2017 4 minutes ago, Ian McP said: Sulzer regulators and their variants are worth investigating https://tangentsoft.net/elec/opamp-linreg.html regards Ian https://linearaudio.nl/sites/linearaudio.net/files/superreg V2.3.pdf Link to comment Share on other sites More sharing options...
stevoz Posted May 18, 2017 Share Posted May 18, 2017 (edited) @catman Hi Felix....Did you realise your first post in this thread is being used on the Akitika link that you provided above as a 'stand alone' review of their product? Here's the line: A User Review of the Phono Preamp You can put this preamp into the PR-101, or you can make your own stand-alone arrangement. One customer did just that. Here's a link to his review Edited May 18, 2017 by stevoz 1 Link to comment Share on other sites More sharing options...
catman Posted May 18, 2017 Author Share Posted May 18, 2017 G'day mate, well I didn't expect that! Regards, Felix. Link to comment Share on other sites More sharing options...
koputai Posted July 9, 2019 Share Posted July 9, 2019 Could someone please tell me the dimensions of the Akitika phono PCB? I want to work out if I can fit it inside an existing pre. Thanks, Jason. Link to comment Share on other sites More sharing options...
Batty Posted July 9, 2019 Share Posted July 9, 2019 (edited) No dimensions on the web site, mine is in the middle of a stack of components that are in use. Edited July 9, 2019 by Batty Link to comment Share on other sites More sharing options...
DogBox Posted July 9, 2020 Share Posted July 9, 2020 Thanks for the links in this thread! Very interesting reading. Yes Catman, that's how 'I' got here! Glad you did such a great job!!! Steve Link to comment Share on other sites More sharing options...
Recommended Posts