Yes, I have also written a lot of emails to him but first time I meet him in person. And fun to meet in his private home to listen to his setup.
Very friendly and relaxed person.
Seems he was testing som drives that was not yet released.
I first bought his SBA NAC-61 small to-ways speakers before I built OBL-15.
Some of his construction require quite a lot of skills with saw and router and also the ability to glue the large wooden parts together with some precision
Think it was this one he mentioned was a little bit hard for some people to built (based on feedback) so will be released in a more "build-friendly" version.......but not 100% sure it was that speaker......but I think so.
http://www.troelsgravesen.dk/Revelator-851.htm
At least it takes more than a few hours to build.
Very friendly and relaxed person.
Seems he was testing som drives that was not yet released.
I first bought his SBA NAC-61 small to-ways speakers before I built OBL-15.
Some of his construction require quite a lot of skills with saw and router and also the ability to glue the large wooden parts together with some precision
Think it was this one he mentioned was a little bit hard for some people to built (based on feedback) so will be released in a more "build-friendly" version.......but not 100% sure it was that speaker......but I think so.
http://www.troelsgravesen.dk/Revelator-851.htm
At least it takes more than a few hours to build.
A friend had a P8 and did not like it. I heard it briefly but only with some records of questionable mastering. This friend previously had a P6 with a 2M Black for a long time and worked in the industry so I believe their ears. They regretted not going for a P10.
I like the way he used the shift registers to separate the channels. I thought that was clever but I guess that would be SOP when using mono DACs with a stereo stream.Dear Wayne a miniDac for da boyz ?
It may well be true, that an ultra high gain phonostage like Pearl 3 would greatly benefit from putting the transformer and AC-to-DC components, into a separate chassis with plenty of electrostatic and electromagnetic shielding. Then locate this separate PSU chassis a few meters away from the microvolt preamp (Pearl 3), with a shielded cable between.
It may be of additional benefit, to also choose a non-toroidal transformer for this application. Regrettably, toroids have quite high primary-to-secondary capacitive coupling, which squirts HF and RF noise from the mains into the secondary. John Curl has often recommended split bobbin transformers on this website, examples below, because split bobbin transformers have extremely low primary-to-secondary capacitance. After all the primary and secondary are wound upon, you guessed it, separate bobbins. Here is one of John's posts on the subject; you can also use the Forum Advanced Search to find quite a few more messages authored by member "john curl" which contain the word "bobbin". Take a look and decide whether you think he's onto something ... remembering that John's been doing world class phonostages for decades; he was awarded the very first US Patent on a Moving Coil pre-preamp (US 4,035,737 in July 1977).
Determined and ambitious hobbyists might choose to go still further, and fully enclose the split bobbin power transformer within a steel can, perhaps one of the round ones sold by Antek for their (not split bobbin!!) transformers, or perhaps a rectangular shielding box made out of mu-metal. The shield can/box prevents the transformer from radiating noise into the rest of the PSU chassis, and also prevents the rest of the PSU chassis wiring from radiating noise into the transformer.
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It may be of additional benefit, to also choose a non-toroidal transformer for this application. Regrettably, toroids have quite high primary-to-secondary capacitive coupling, which squirts HF and RF noise from the mains into the secondary. John Curl has often recommended split bobbin transformers on this website, examples below, because split bobbin transformers have extremely low primary-to-secondary capacitance. After all the primary and secondary are wound upon, you guessed it, separate bobbins. Here is one of John's posts on the subject; you can also use the Forum Advanced Search to find quite a few more messages authored by member "john curl" which contain the word "bobbin". Take a look and decide whether you think he's onto something ... remembering that John's been doing world class phonostages for decades; he was awarded the very first US Patent on a Moving Coil pre-preamp (US 4,035,737 in July 1977).
Determined and ambitious hobbyists might choose to go still further, and fully enclose the split bobbin power transformer within a steel can, perhaps one of the round ones sold by Antek for their (not split bobbin!!) transformers, or perhaps a rectangular shielding box made out of mu-metal. The shield can/box prevents the transformer from radiating noise into the rest of the PSU chassis, and also prevents the rest of the PSU chassis wiring from radiating noise into the transformer.
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Attachments
John does like the split bobbins or C core type. Toroidal types tend to have very wide bandwidth also.
They can couple noise in and out well. I still like a toroid sonically for some reason, maybe the wrong split bobbin types.
My Pearl 3 is in a single box and pretty quiet with an Avemco 25 VA toroid off on one side. This being diy I expect two transformers in a secondary box with high speed diodes and a couple of farads of polypropylene caps.
They can couple noise in and out well. I still like a toroid sonically for some reason, maybe the wrong split bobbin types.
My Pearl 3 is in a single box and pretty quiet with an Avemco 25 VA toroid off on one side. This being diy I expect two transformers in a secondary box with high speed diodes and a couple of farads of polypropylene caps.
@rhthatcher Has made a great little PCB with CRCRC filtering for the raw supply. Ive got a few to try, as well as some other solutions… this is going to be fun!
Here's a subversive idea: as Wayne suggested, two transformers in a separate box . . . BUT, connected in series. The first one is a 1-to-1-ratio isolation transformer (230V --> 230V or 115V --> 115V) and the second one is a conventional 2x22VAC R-core or C-core split bobbin transformer.
The isolation transformer attenuates common mode noise AND HF-RF grunge, by the ratio C-winding-trafo1 to C-external-bigazz .
The isolation transformer attenuates common mode noise AND HF-RF grunge, by the ratio C-winding-trafo1 to C-external-bigazz .
The Optimal RIAA PSU?
A Large cluster of lead acid batterys with a new old stock WW2 era submarine diesel driving the, sun following, gigantic solar panel array. Guided by a mechanical watch and with 300B tube based linear DC regulation.
The Diesel Engine rotating the sun following solar panel array:
A Large cluster of lead acid batterys with a new old stock WW2 era submarine diesel driving the, sun following, gigantic solar panel array. Guided by a mechanical watch and with 300B tube based linear DC regulation.
The Diesel Engine rotating the sun following solar panel array:
Very nice!! It includes a common mode choke, EMI filtering, mains fuse, and front panel pilot light too. Great find. (link to model BP-1000 datasheet)
They will probably not do what I ask for......but maybe I get an answer......if not Wayne already has asked........
I live relative close to them so I could "pick up" one
I got an answer to the question about a cartridge with centertap. I wrote in Danish and the answer was in English. I think he understood the question?
I blinded out his name just to be "GDPR-safe".
It seems they look into it.
******************************************
Hello ,
Thanks for your inquiry.
We currently do not manufacture anything with a discrete ground pin, but we are investigating the possibility of doing so.
Best regards
xxx yyy
Product Specialist
Stavangervej 9
DK- 4900 Nakskov
E-mail: support@ortofon.dk
Website: www.ortofon.com
********************************************
It seems the name of the person that answered my mail is already out various places. E.g. in this article in line 3:
https://6moons.com/audioreviews/thorens2/550_2.html
Seems he is a known person in the turntable "niche" community?
https://6moons.com/audioreviews/thorens2/550_2.html
Seems he is a known person in the turntable "niche" community?
While all are anxiety prone over split bobbin trafo etc. consider this -- mentioned in another thread -- you can get a Murata DC-DC converter and use a pair of the Analog Devices ultra low noise LDO's to obviate the problem (now that the rail voltage is a mere +/-15VDC). As I have mentioned previously, these have excellent PSRR, very low Z-out and ultra low noise.
Hello,
This is all over the deep end.
For $200 you can purchase a Cambridge Audio RIAA Preamp.
As with most of these DIY projects the power supply will be the challenge and cost more than the amplifier.
Then after all that the Cambridge Audio RIAA Preamp will test / perform better.
It is for entertainment I guess, not emergency backup for FedEx or Visa computers.
Thanks DT
This is all over the deep end.
For $200 you can purchase a Cambridge Audio RIAA Preamp.
As with most of these DIY projects the power supply will be the challenge and cost more than the amplifier.
Then after all that the Cambridge Audio RIAA Preamp will test / perform better.
It is for entertainment I guess, not emergency backup for FedEx or Visa computers.
Thanks DT
The Toroidy transformers many used for building Iron Pre (incl. myself) turned out to be very quiet (with both magnetic / electrostatic shield). But such a sensitive phono preamp calls for the transformer it its own chassis (at least one also did that for IronPre)?
The Gemini-part of the ironPre boards could be used for this project (instead of the 7815/7915?). I assume such a complicated shunt regulator should be just a little more silent than standard voltage regulators? .....assuming that the P3 power consumption does not exceed that of the ZM Gemini......
The Gemini-part of the ironPre boards could be used for this project (instead of the 7815/7915?). I assume such a complicated shunt regulator should be just a little more silent than standard voltage regulators? .....assuming that the P3 power consumption does not exceed that of the ZM Gemini......