202 VDC is very very nice to hear. My new design goal, going forward, is 200 VDC plus or minus 5 VDC. No wonder you have been pleased. Happy listening !!
Finally my DIY tube amp project gets kick-started
- Thread starter Hari Iyer
- Start date
@Hari Iyer , could you please share the contact details of the Poshan OPT, and the price for a pair of POS-76UDCF?
I tried to contact them through their website but haven't heard back.
I have sent you a PM.
Hi Kartik,
The whatapp contact details of POSHAN are available in his website. Number +852 9883 1803.
The total cost paid inclusive of shipping via ups is Hkd3300/-. Custom duty paid is 12500/-. Total landed cost is approximately 46500/- for one pair. Hope this helps
Thanks Hari. It would also help if you can extensively listen to these new trafos, break these in and then let us know the key differences. A lot of times our mind does not let us draw unbiased comparisons for the new things that we buy and specially those which we expect to sound better. Live with it for a while and then, ideally if possible, go back to your Delta trafos, and you will know immediately, about the key differences and is it worth spending additional on these POSHANs? I'd be very keen to learn your observations, whenever in the future you'd have the time. Cheers.
Thanks Kartik, I have listened to the delta now for 400+ hrs past 3+ months which had undergone substantial break-in for 2+ years 5 years ago. I can say that Delta's are very refined Transformers and have a mellow sounding at the mids and highs with out announcing their presence but just making them felt. Those who are on the look out for airy highs and screeching vocals look elsewhere.
The POSHAN's have completed just around 25+ hrs past 10 days on average, so it's too early to judge them. Every day they tend to sound a little bit smoother and refined. These are more resolved and quite airy in comparison to the Delta's. Poor recordings and some MP3 may sound fatigued in this currently due to its resolution and detailing. I am expecting bass to further improve after 70+ hours.
Also I have noticed some differences in SQ with the two passive preamplifier that I have been using -
1) the one with Allo stepped attenuator which has a E251 0.1% MFR for its voltage attenuation sounds more airy, brighter and detailed.
2) the one that uses Alps carbon wiper control potentiometer is very very mellow and to my liking currently.
Those who believe that these things don't matter are either fooling themselves or living in a different bi-parallel world. Period.
I really don't know why, but again both do sound good and it's personal preference at the end of the day.
Some high end stuff use carbon composite resistors in the input stage. There may be some wisdom in that. I have also seen in my Marantz blueray player there are carbon film resistors in the final stage just before they are connected to the RCA jack, rest all is MFR. These carbon film tend to give soft, mellow and warmer sound compared to MFR - no matter what the specs say or the noise guru say.
Early last week replaced all internal wiring of pre-amplifier from mil spec silver plated copper to solid silver with Rodhium plating. Now my IC is also with this wire from source to preamp. As I was running short of wire from preamp to monoblocks am using 30awg enameled copper wire for IC
These wires are non- shielded but I am not picking any RF or EMI noise any where.
In the monoblocks the input wire is Solid silver with gold plating and the direct couple wire is Rodhium plated silver. With these modifications all activities related to pre-amplifier and monoblocks are fully completed.
Thanks for looking.
These wires are non- shielded but I am not picking any RF or EMI noise any where.
In the monoblocks the input wire is Solid silver with gold plating and the direct couple wire is Rodhium plated silver. With these modifications all activities related to pre-amplifier and monoblocks are fully completed.
Thanks for looking.
Hi Arjun,
I have tried various wires earlier - stranded copper, solid copper, tinned copper, silver plated copper and finally settled with Rodhium plated solid silver. I have found less glare in the mid bass and upper highs with Rodhium plated silver compared to other wires. The vocals are more focused with silver and with other wire it's some what bloated and unnatural IME.
I am not sure if the Rodhium is the cause for this balanced sound as Rodhim is just 38% conductivity compared to 106% of silver. So the HF which travels through the skin gets the Rodhium while mids and lows gets the solid silver. Also the awg is 22 awg so everything is forced to travel through the small wire giving it much balance.
Using Rodhium plating helps to reduce time smear between lows, mids and highs and the associated phase shift.
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Finally got settled with the new speaker cable gifted to me by my Audio Guru @drlowmu 2 weeks ago. It's made up of mil spec silver plated copper wire 12 + 12 +14 awg lightly twisted to make 8 awg overall. Termination is vampire copper spade with Gold plating. These are made to Fulton length 114.25" long. There are 4 such wires. The hot and cold polarity of the wires don't touch each other to eliminate all capacitance between them. These wires are floating suspended in air not touching the floor.
These are the best speaker wires I have ever used till date. No subjective comments or evaluation as these may become very speculative and personal. What is music for me would be colouration for you and vice-versa as we all listen so differently. What matters for me is that I have finally reached the end with that. A big Thanks to Jeff for the gift.
These are the best speaker wires I have ever used till date. No subjective comments or evaluation as these may become very speculative and personal. What is music for me would be colouration for you and vice-versa as we all listen so differently. What matters for me is that I have finally reached the end with that. A big Thanks to Jeff for the gift.
IndianEars
Well-Known Member
Would be lovely if you could post a picture of the cables.
Thanks
Thanks
Last month I had replaced the Poshan Double-C core OPT with the recommended Softone R-core OPTs. The Softone are a perfect match for my tube amplifier. They require around 400+ hrs of break-in and I have completed around 100+ hrs.
I have now used 4 different OPTs with my tube amplifier and here are my ratings on a scale of 10.
- Dared EI OPT rating 2
- Poshan Double-C core rating 4
- Delta EI core rating 6
- Softone R-core rating 9.5
The only reason I am not giving a perfect 10 to the Softone is because I have not listen to Tango or Audionote.
I have spent a fortune on the OPTs and finally am glad that it went perfect for me.
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I have now used 4 different OPTs with my tube amplifier and here are my ratings on a scale of 10.
- Dared EI OPT rating 2
- Poshan Double-C core rating 4
- Delta EI core rating 6
- Softone R-core rating 9.5
The only reason I am not giving a perfect 10 to the Softone is because I have not listen to Tango or Audionote.
I have spent a fortune on the OPTs and finally am glad that it went perfect for me.
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I can understand the cost of OPTs
This week I calculated the Miller capacitance of my input driver tubes and found that to be around 93 pF. My input grid resistance was around 430 k. This gave me a roll-off of around 4.1 KHz. I wondered if I could reduce the resistance to around 100k, the roll-off would be around 15.2khz. I. did this change yesterday with positive outcome and now have a wider bandwidth particularly at the top end. Looking at the improvement I may plan to reduce the input resistance to around 82k to get full 20 kHz bandwidth. Ironically there is no oscillation, buzz or RF noise with this change.
Thanks for looking.
Thanks for looking.
After one month of working with grid to ground resistance, I finally restored to the original value of 430k. Reduced resistance gave me the required bandwidth but they sound unnatural to my ears and I lost micro detail while ganing macro detail.
Original resistance was metal film type and gave me somewhat bright signature and a little compressed in high resolution recordings. I tried 500k carbon film and the HF dropped a lot not to my liking. Wanted to try carbon composite, and did a work around of using a 470k SATO preset (large - which usually are carbon composite) and adjusted that to 430k ohm. I have been listening this for 2 days and am liking what I have heard. Hope the resistance don't drift over time. Planning to buy a fixed carbon composite, but the shipping charges are killing.
Original resistance was metal film type and gave me somewhat bright signature and a little compressed in high resolution recordings. I tried 500k carbon film and the HF dropped a lot not to my liking. Wanted to try carbon composite, and did a work around of using a 470k SATO preset (large - which usually are carbon composite) and adjusted that to 430k ohm. I have been listening this for 2 days and am liking what I have heard. Hope the resistance don't drift over time. Planning to buy a fixed carbon composite, but the shipping charges are killing.
How do you " adjust" 470K to 430K Ohms?? That 430K value was determined by ear in the USA, before it was ever specified to you in 2020.
In transparent audio implementations, you can NOT add two unequal value resistances in parallel ...............and achieve OPTIMAL sonics. It produces a skew in such gear. Match paralleled Rs to 1% or better yet 0.1% if in a critical position.
My main thought Hari : How do we know that your resistor choices are being done to complement other , less than ideal implementations in your system, such as your source or your interconnect wires??? This causes concern to me. Time to telephone Montana, or, send a letter.
Have 35 minutes ??? See and hear this !!
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The 470k is an adjustable variable resistor ( preset) and was adjusted to the original value of 430kohms. I used this because it's a carbon composite type. The earlier MRA-3 sounded a bit brighter to my ears. The preset sound much mellow to me.
I am using Belden 32awg silver wire as interconnect cables and they match quite well to these modifications. The metal film though detailed had an artificial edge not to my liking. Changing the IC cable to commercial cable did not resolve this issue and hence went ahead to modify the resistor
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