nicoch46 said:
Hi nicoch46
I am using an Ariston RD80 TT with a DIYGeddon PSU.... this PSU made quite a difference.
The speakers are very old and I will modd them after I finish the Riaa.
The power amp (103) is quite amazing... Almost as dynamic as my DENON POA6600 but in a smaller scale.
Ricardo
Good work vgeorge. This phono has all the potential for tuning it to your preference and system demands. It will not disappoint you in the long run. Regarding the toroid chokes you use, keep in mind that they lose most of their inductance at the constant currents employed in the particular shunts. They are working mostly as RC filters now. I would advise EI gaped chokes. Hammond has cheap and adequate. They must have 200mA nominal inductance spec. Don't worry if they are 1H or less. Non the less, the shunts alone are particularly silent for self noise, this is cross checked. What kind of system you got? TT etc.? What about your friend's system?
Shunt boost mod
I have already told you that I had a simple boost mod on test regarding the shunt. After much listening in the high MC version and cross check in the double PSU MC version in another system, I can recommend it as positive. It manifests itself more when the shunt is common between channels. I perceive a little smoother and wider low and high treble mainly and some better ''togetherness'' from bass up. Since the gain of the comparison loop between reference and regulation is gm(Q3)*R6, Janneman and syn08 (top professional engineers normally contributing in the solid state section) suggested to add just another CCS instead of the resistor for boosting that loop. Why not, since the parts count remains the same and nothing is fundamentally changing. It shows better in simulation too, as Ikoflexer simulated it.
The mod is so easy to do, that anybody that made the shunt can try it and give an opinion. Basically you take out R6 (the load resistor of Q3 BC550C Mosfet driver) and you put a 2SK170 in its place, with g, s, legs soldered together towards the BC550c's collector. The d leg goes up to the +Vout line. Use up to 7-8mA IDSS, because it boosts the working current of the BJT and its better to be wise with its long term reliability, especially in the over 30V Vout versions. Here is an example, for the 25V version.
I have already told you that I had a simple boost mod on test regarding the shunt. After much listening in the high MC version and cross check in the double PSU MC version in another system, I can recommend it as positive. It manifests itself more when the shunt is common between channels. I perceive a little smoother and wider low and high treble mainly and some better ''togetherness'' from bass up. Since the gain of the comparison loop between reference and regulation is gm(Q3)*R6, Janneman and syn08 (top professional engineers normally contributing in the solid state section) suggested to add just another CCS instead of the resistor for boosting that loop. Why not, since the parts count remains the same and nothing is fundamentally changing. It shows better in simulation too, as Ikoflexer simulated it.
The mod is so easy to do, that anybody that made the shunt can try it and give an opinion. Basically you take out R6 (the load resistor of Q3 BC550C Mosfet driver) and you put a 2SK170 in its place, with g, s, legs soldered together towards the BC550c's collector. The d leg goes up to the +Vout line. Use up to 7-8mA IDSS, because it boosts the working current of the BJT and its better to be wise with its long term reliability, especially in the over 30V Vout versions. Here is an example, for the 25V version.
Attachments
Also a practical example picture. You can see the JFET (the one with the g, s, legs together next to the shunt Mosfet on the left) in place of a previously 1k resistor that was sitting there. I just cut the resistor out, and soldered the 2SK170 on its remaining already soldered to perf board legs. Some early fears for oscillation dangers from the boost proved no real concern. It works fine in 4 shunts for a couple of days now already.
Attachments
Hi Salas,
thank you again for the informations. I am not the most experienced here! I will try and find these hammond chokes in the future. I used these because I had them, as the tansformer is from an old class a amp! I play now with an 560 resitor and sound is nice. I thinks it opens with every hour of play.
I have a VPI Aries first gen with a rega rb300 arm VDH rewired and Shelter 901. I also have a Denon DL 103 as backup.
Amps are an F5 for mid tweeter and a mc cormack dna-1 for the bass.
Speakers modified Basszillas, with bigger bass box and Lambda TD15X woofer.
For pre I use now either a 10k passive pot or jfet boz. My next plan is a very good pre, maybe a tube one, but for next winter maybe.
My frien is much older than me and very expirienced builder. He has the same cartridge as I do, an old but very good quality Luxman player and electronics of his made, not sure excactly.
Now let' s try your last mod!
thank you again for the informations. I am not the most experienced here! I will try and find these hammond chokes in the future. I used these because I had them, as the tansformer is from an old class a amp! I play now with an 560 resitor and sound is nice. I thinks it opens with every hour of play.
I have a VPI Aries first gen with a rega rb300 arm VDH rewired and Shelter 901. I also have a Denon DL 103 as backup.
Amps are an F5 for mid tweeter and a mc cormack dna-1 for the bass.
Speakers modified Basszillas, with bigger bass box and Lambda TD15X woofer.
For pre I use now either a 10k passive pot or jfet boz. My next plan is a very good pre, maybe a tube one, but for next winter maybe.
My frien is much older than me and very expirienced builder. He has the same cartridge as I do, an old but very good quality Luxman player and electronics of his made, not sure excactly.
Now let' s try your last mod!
You are welcome! I understood that you had the chokes already. I just wanted to inform you about their real behavior because I have tested them in various currents in the past. They are not in spec above 20mA, they lose inductance very soon. They are contributing their parasitic resistance for RC at 200mA mainly and a little inductance. Which is good enough when feeding 22mF. Your system is advanced DIY, and I like the TT and arm, cart. Lets see if you perceive the mod as much, bcs you already have double regs. The lowering of the reg's output impedance and regulation boost, helps single reg situations the most, naturally.
Rcruz,
I found some auricaps on a site on my work computer, I will tell you tomorow. I haven' t made an order yet. I am also thinking to buy Mundorf Silver. I haven' t decided yet. Any suggestion is welcome!
I just changed output caps with 2.2 SRC tin foil bypassed with .047 POI. Sound is much better. Thank you for your kind words.
Regards
George
I found some auricaps on a site on my work computer, I will tell you tomorow. I haven' t made an order yet. I am also thinking to buy Mundorf Silver. I haven' t decided yet. Any suggestion is welcome!
I just changed output caps with 2.2 SRC tin foil bypassed with .047 POI. Sound is much better. Thank you for your kind words.
Regards
George
Because he just calculates them at such nominal current based on wire diameter, and then uses a hand held LCR meter at 1kHz with rudimentary current if you ask him to check the inductance, does not mean that the non gaped 50VA-100VA toroidal cores are made for any other application than AC mains transformers. Toroidal cores are notorious for hating DC and go to saturation fast. Just look around in the web and try to find many offered PSU chokes in toroidal core in the 100's of mA... If it was a valid approach, it would have been everywhere. I checked them thoroughly because I had various of his toroid types in the past, and they never filtered ripple as expected above 20mA. Their nominal inductance is just wishful thinking at nominal current, the guy is decent, don't get me wrong. He maybe misses the part that a toroid core to be good for some DC needs specially distributed gap core with Mylar or Teflon separators between layers. Those cores are special, very expensive, not usually found off the self. To the contrary, you can ask him to make EI gaped chokes for your specs and they work as a charm. He does good work.
Something like a Hammond 158s is good for passively pre filtering my shunts at 200mA CCS IMHO, without losing much voltage. You would need 2 of them, or like them. And you must have enough voltage for accommodating the drop on their 60R series. How much series resistance your now chokes have?
Something like a Hammond 158s is good for passively pre filtering my shunts at 200mA CCS IMHO, without losing much voltage. You would need 2 of them, or like them. And you must have enough voltage for accommodating the drop on their 60R series. How much series resistance your now chokes have?
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vgeorge said:
Look online for the Hammonds, they aren't heavy so it may be best to get em off ebay or some EU online store. Ask for freight costs in advance.
Both are very good capacitors. I prefer Auricaps when there is hardness potential in the rest of the set up, especially in speakers. The Mundorf has some hyped up detail but in a liquid manner and I find it a bit skinny in the power range (200Hz-800Hz). Depends very much on your total TT tone and speaker - room interface.
Will do....salas said:Measurement wise, I could not see so much improvement as in the simulation, but it lowered the noise floor in the range between 5k to 20kHz. This ties with the added subjective smoothness I perceived in the highs. Waiting to know gang's opinions too.
Just a question.... As my shunt is 10cm away from the riaa, and as I know that we should place the regs as close as possible to the circuit to be powered, I was wondering if adding 2 caps (1 per channel) in the Riaa pcb decoupling the power line would produce some beneficial results ?
As my shunt has a 470u BG std in the output, i would like to place 2 x 680u BG Nx in the Riaa.
Ricardo