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Finally my DIY tube amp project gets kick-started

Wharfedale Linton Heritage Speakers

sdk

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Was wondering if GOD does mundane boring things like sunrise and sunset with so much precision, then won't HE know how to make a power cable?
Tut, tut, tut

How do you know it's a HE? And not a SHE? :p

Not to forget the rainbow colours that are available too!
 

Hari Iyer

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Tut, tut, tut

How do you know it's a HE? And not a SHE? :p

Not to forget the rainbow colours that are available too!
It does not matter to me if it's a HE or SHE, what matter to me is wether HE or SHE knows to make a "Power Cable".
 
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Hari Iyer

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Well done Hari, looking forward to further impressions...
Thanks Susnick, the Hammonds 159z takes around 200hrs for break-in and the tubes around 70 hrs. Capacitors will take another 300hrs and around 50hrs to 60hrs for the wires and solders. Will post my listening impression post that. Also my stock OPT will need to be replaced by Softone after a while when they are available. Till then stay tuned.

Cheers,
 

Hari Iyer

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Last week and this made some interesting discoveries concerning power supply topology in tubes and how much they affect overall tone of an amplifier. It makes me wonder that how much we discuss about power cables and it's impact which could be either minute or huge without giving much thought about how good are the amplifie's power supply is actually designed. What I want to say is don't pour money changing power cables if your amplifier's and other components of your gear's power supply is just basic. Only if you have a well designed power stage in your amplifier will any change in cable will actually matter ( if at all).

In this DIT tuve amplifier I have used 2 chokes each in my power stage in an LCLC arrangement and they cost almost 10k for four numbers. But the correct tonality and dynamic range came from replacing the 2 chokes with an 200 watts incandescent lamp and I have now changed the confirmation to RCRCRC ( Where R is an incandescent lamp of 100, 200, 200 watts each). Total cost just 100/- for both channels . Almost 100 times lower than using chokes. I have now listened for a week and posting after that. I also did a simulation with PSUD2 why the lamps sound better than the chokes to my ears and discovered that there is a rectifier pulse noise using chokes which is not present in the bulbs. Also the current drawn by the load (amplifier) during the draw cycle is pulsed and noisy and also not in-phase with the voltage with chokes, but with bulbs it's clean DC draw not pulsed and in-phase with voltage. All this simulation made me wonder how much time and money we spend on power cables, where the solution could lie somewhere else which could be very cheaper and better.

Now with this topology I can't now say it's same as originally designed by Jeff, but a modified version of his design.

Thanks for looking.
 

Hari Iyer

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After countless discussion and testing I removed the bulbs and now they are back to original design. Have added an hash choke just after the transformer center tap which is under testing. May decide later if that need to be retained or go.

Yesterday added bypass capacitors (24 of them in both monoblock) and vacuumed the amplifier to remove all solder / plastic debris. Now only two final changes are pending - replace the top wooden plate to brass and change the OPT. Both these will have to wait couple of months. Till then just relax and enjoy the music

Thanks for looking.
 

sdk

Active Member
Joined
Sep 28, 2014
Messages
153
Points
28
Location
Mumbai
Last week and this made some interesting discoveries concerning power supply topology in tubes and how much they affect overall tone of an amplifier. It makes me wonder that how much we discuss about power cables and it's impact which could be either minute or huge without giving much thought about how good are the amplifie's power supply is actually designed. What I want to say is don't pour money changing power cables if your amplifier's and other components of your gear's power supply is just basic. Only if you have a well designed power stage in your amplifier will any change in cable will actually matter ( if at all).

In this DIT tuve amplifier I have used 2 chokes each in my power stage in an LCLC arrangement and they cost almost 10k for four numbers. But the correct tonality and dynamic range came from replacing the 2 chokes with an 200 watts incandescent lamp and I have now changed the confirmation to RCRCRC ( Where R is an incandescent lamp of 100, 200, 200 watts each). Total cost just 100/- for both channels . Almost 100 times lower than using chokes. I have now listened for a week and posting after that. I also did a simulation with PSUD2 why the lamps sound better than the chokes to my ears and discovered that there is a rectifier pulse noise using chokes which is not present in the bulbs. Also the current drawn by the load (amplifier) during the draw cycle is pulsed and noisy and also not in-phase with the voltage with chokes, but with bulbs it's clean DC draw not pulsed and in-phase with voltage. All this simulation made me wonder how much time and money we spend on power cables, where the solution could lie somewhere else which could be very cheaper and better.

Now with this topology I can't now say it's same as originally designed by Jeff, but a modified version of his design.

Thanks for looking.
Where did you manage to buy incandescent bulbs? Please could you share the source?
 

IndianEars

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Great to know that you have removed the incandescent bulbs. They are extremely non linear and yield very very poor Power Supply regulation. They probably introduced huge distortion as the volume is cranked up or with dynamic music.

Series bulbs are great as a Self Protection circuit, when testing an amplifier for first switch on, or during repairing.

If used as a permanent circuit element, they will create a non linear "lamplifier".

Incandesent bulbs have been used as series elements in Public Address speakers to prevent them from damage. Bise used them in their pro audio (not domestic audio) speakers.

Several decades ago, BEVOX (Bajaj Electronics) used them as emitter resistors in their solid state amps, creating their 'lamplifier'.

Almost never used today except during testing.
 

Hari Iyer

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Thanks @IndianEars for your perspective. I agree the incandescent is non-linear and a peak current limiter. They helped me to realise few things about my amplifier. How much DCR is affecting dynamics, how good an RC filter helps to filter ripple and how they can Rob music of its transients. I won't put this as a futile exercise in my learnings. I believe DIY is all about discovering the magic sound that you have dreamt about. If I can't try various combinations and permutations of component choice and various design ideas then there is no point in going DIY and just building as per original design which most of DIYers do. Imo, each one of us hears differently and if you cannot tailor the sound to your taste then DIY is waste. For that you need a good understanding of what you are looking for and what tweaks work or don't work for you. It's better to have a design that's scalable over time.

Now the amplifier is back to the original design and have completed around 250+ hours of break-in and they sound quite refined after the burn-in without harshness or over energitic. Did some modifications on the preamplifier internal wiring which had an influence on the overall sound presentation. I am not planning any more mods to this amplifier other than replacing the OPT and the top cover and I am done.
 

Hari Iyer

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Next week I shall be trying some bare solid silver wire 97% purity with pin hole gold plating for my preamplifier internal wiring (thanks to FM @yogibear for sending this wire to me). My current 26 awg X 2 silver plated copper wire is already very mellow and neutral. Let me check if the solid silver wire can better them.

I have tried various internal wiring wires like solid copper, stranded copper, solid silver plated copper, tin plated copper and none of them could match with my monoblocks for transparency and neutrality.
 

Hari Iyer

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It seems the Softone OPT is not going to be available for a long time due to supply chain disruption aftermath of Covid 19. I have been searching for other options agressively and may mostly settle with a orient super HiB double c core type OPT. They are a bit more expensive than Softone and Hoshimoto but again I don't have an option as of now. I have waited for this for over 4 months now, but I am unable to see light at the end of the tunnel. Imo, EMS India is using Covid 19 as a business strategy and are avoiding any imports. Almost 90% of countries have resumed EMS airfreight other than few like India and US.
 

Hari Iyer

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Hari,

Does any friend on this Forum know of people who travel back and forth, India to Japan and back, so they can personally help to get you a pair of Softone RW-20s???
Good suggestion Jeff, but most corporate offices have not resumed international travel ( including mine) and that will continue for atleast 6 more months if my guess is correct. If anyone traveling to Japan and back read this post - please contact me.
Thanks,
 
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