There have been lots of discussions in this thread about exploring options to build a tube power amp for tube beginners in India, given our serious constraints about sourcing parts. We've actually located one veteran transformer manufacturing company which has designed and built their own range of audio OPS transformers for tube amps. There's at least one brand of high-end Indian tube amps which uses these transformers with excellent results. This encourages us to try a full amp.
There are of course a large number of other exotic components to source, and there's the tube-inexperience of most of us to also take into account.
Starting a new thread to take all this discussion forward. Looking for inputs/ideas from all over the world, of course, though some of the parts decisions may be taken based on sourcing constraints for us in our Glorious Motherland.
There are of course a large number of other exotic components to source, and there's the tube-inexperience of most of us to also take into account.
Starting a new thread to take all this discussion forward. Looking for inputs/ideas from all over the world, of course, though some of the parts decisions may be taken based on sourcing constraints for us in our Glorious Motherland.
Do you have problems with importing things from the postal service? I have heard there is a lot of corruption and theft of postal items in some countries. If it is OK, you may wish to source some of the capacitors and valves from the former Soviet states. I have not had a problem with shipping or bad goods from any of the ebay sellers of this stuff. Of particular interest might be the small signal valves such as 6N1P, 6N2P, 6N23P and output valves such as 6P3S (6L6) 6P14P (EL84) and 6P15P (EL83).
Good luck with the projects. If there are any good sources for gear in Mumbai, let us know, I get there once or twice a year.
Chris
Good luck with the projects. If there are any good sources for gear in Mumbai, let us know, I get there once or twice a year.
Chris
In India, the postal service is not bad at all. It is the customs duty etc which sometimes makes it too expensive to import. That has been the problem for Indian DIYers otherwise there is no problem for Indians to order from sites like ebay. The Indian ebay does not stock DIY audio stuff.
Vivek
Vivek
Great!! More than the economics of a group buy, im personally more interested in picking the brains of the more experienced builders in India and learning a lot more about audio electronics through this project. Another advantage would be that as a group buy, most of the purchases can be staggered over the period of the build : one year by some estimates, keeping things nice and happy at home Hope to see the more experienced posters from India piping in on this thread soon.
Hope to see the more experienced posters from India piping in on this thread soon.Hi,
Am member of this forum from very very long time but a passive one !!
Its nice to see that finally indian group buy taking place !
Tarun Rikhav has said soo much about you !
Vivek how are you buddy ?? long time no see !!
Will be watching very closely the developments of this thread !
Regards.
Am member of this forum from very very long time but a passive one !!
Its nice to see that finally indian group buy taking place !
Tarun Rikhav has said soo much about you !
Vivek how are you buddy ?? long time no see !!
Will be watching very closely the developments of this thread !
Regards.
Vivek said:
Isn't it duty-free to import upto 25,000 rupees of items at one-time, especially electronics? I think that even if the group buy orders exceed this amount, the fact that it is an import of components rather than fully-built up systems should qualify for lower duties. Will need to get more info more the DGFT website.
Tarun:
I am willing and able to share my experience to assist this project going forward..
AFAIK, the 25K exemption limit is for baggage when one comes in from abroad, and not for stuff that is sent through the postal dept.
Going out from my earlier post, one needs to define output. My guess is that the range of 30+ wpc is fine, and one can easily consider a Dynaco clone, without getting into scratch building. The transformer specs are available, and all it needs is reverse engineering of the transformers, without getting into any IP issues.
I have a pdf copy of the Dynaco assembly manual that can be sent to anyone interested. One needs to look at what the cost of the mains tranny and output tranny will be, to get some idea about costing. The chassis, valves, choke and hardware are other cost items, and most Dynaco clones have a driver board that is offered by various vendors.
At the upper price band look here:
http://www.avahifi.com/root/equipment/amplifier/ultimate70.htm
There is another from Curcio Audio( Dynaco-doctor), and Triode Electronics also offers these, as does Welborne Labs.
Once you guys do some research and understand what are the various components, it gets a bit easier.
I am currently in the process of redoing a similar amp(Welborne Labs ST-70), and have done some research, so I can share some info with you. My amp was a kit from the US, using Magnequest output transformers, but I got it assembled many years ago by a friend who had very little experience in valve amps-though he was a PhD in physics and knew all about ss amps. The net result was that he made a hash of it.
I am now trying to salvage it, using an avahifi board that I have ordered, and hope it will come out right. In the meantime I have two other valve amps to play around with, so this is a low priority project for me at this time.
(As an aside: I have an unused, surplus board, with detailed assembly manual, with components, except tubes, mounting plate, chassis, hardware and trannies that I bought some years ago from Welborne Labs for a similar amp-for details see:
http://www.welbornelabs.com/st70.htm
The item I have is the ST 70A-if anyone wants it, after he has done all of the research, please let me know. I can offer it at cost. However, one needs to factor in all the rest of the stuff, to arrive at a more accurate costing of this amp as a project. Merely buying this will not be enough..)
I am willing and able to share my experience to assist this project going forward..
AFAIK, the 25K exemption limit is for baggage when one comes in from abroad, and not for stuff that is sent through the postal dept.
Going out from my earlier post, one needs to define output. My guess is that the range of 30+ wpc is fine, and one can easily consider a Dynaco clone, without getting into scratch building. The transformer specs are available, and all it needs is reverse engineering of the transformers, without getting into any IP issues.
I have a pdf copy of the Dynaco assembly manual that can be sent to anyone interested. One needs to look at what the cost of the mains tranny and output tranny will be, to get some idea about costing. The chassis, valves, choke and hardware are other cost items, and most Dynaco clones have a driver board that is offered by various vendors.
At the upper price band look here:
http://www.avahifi.com/root/equipment/amplifier/ultimate70.htm
There is another from Curcio Audio( Dynaco-doctor), and Triode Electronics also offers these, as does Welborne Labs.
Once you guys do some research and understand what are the various components, it gets a bit easier.
I am currently in the process of redoing a similar amp(Welborne Labs ST-70), and have done some research, so I can share some info with you. My amp was a kit from the US, using Magnequest output transformers, but I got it assembled many years ago by a friend who had very little experience in valve amps-though he was a PhD in physics and knew all about ss amps. The net result was that he made a hash of it.
I am now trying to salvage it, using an avahifi board that I have ordered, and hope it will come out right. In the meantime I have two other valve amps to play around with, so this is a low priority project for me at this time.
(As an aside: I have an unused, surplus board, with detailed assembly manual, with components, except tubes, mounting plate, chassis, hardware and trannies that I bought some years ago from Welborne Labs for a similar amp-for details see:
http://www.welbornelabs.com/st70.htm
The item I have is the ST 70A-if anyone wants it, after he has done all of the research, please let me know. I can offer it at cost. However, one needs to factor in all the rest of the stuff, to arrive at a more accurate costing of this amp as a project. Merely buying this will not be enough..)
Amp power -interesting read from Welborne, somewhere in the middle of the page.
http://www.welbornelabs.com/recomendspeaks.htm
http://www.welbornelabs.com/recomendspeaks.htm
gjo said:
Right you are. From what I can gather online, valves/tubes for amplifiers are charged at 12.5% specific duty per piece. Other components such as potentiometers, resistors, capacitors are duty-free. I think once there is some interest in the build and a consensus on the BOM, then looking into what needs to be imported and whats locally available would make sense.
Hmmm, so where do we start? Listing out the speakers that need to be driven and the power output needed? In my case, I have a Bose Acoustimass 5 speaker system (circa 1990) and Polk Audio Monitor 30s. Efficiency is 89db for the Polks and as for the Bose, I don't think I'll ever find out In terms of future-proofing my system, I'm pretty sure I won't be getting into horns so Polk is it for now (Bose being used more for driving the DVD player output)
In terms of future-proofing my system, I'm pretty sure I won't be getting into horns so Polk is it for now (Bose being used more for driving the DVD player output)Parts in India
Some suggestions on the availability of parts in India:
Valves - lots of old stock of BEL (Bharat Electronics Limited) still available. Look up your local electronics "kabadiwalla"! And old movie projector parts suppliers.
Input/driver ECC82, ECC83
6SN7 Russian and US, army surplus
Output EL84, ECL86, ECL82 (sorry, only low power)
Rectifiers GZ34, EZ81, EZ80
So, these should be available for around Rs.100 each. You'll have to import only the bigger power valves. I recommend the JJ E34L -they are very robust, and great value.
Resistors and capacitors - lots of good quality parts available.
Resistors stay with 1watt carbon film Thakor, Thermax
cheaper, sound better.
metal film gives a brittle edge to the sound.
Capacitors film caps, 0.01 to 4.7uF/400V CTR
start out with these, then add your flavour with
imported caps.
Electrolytics 22 to 100uF/450V Samwa
Korean, cheap and good
easily available, thanks to the computer/inverter industry
Hookup wire teflon insulated single or multistrand copper
check with local suppliers.
Connectors RCA, binding posts MX
there has to be a stockist in your city.
Switches/electrical Elcom an industrial supply manufacturer.
Volume pots nothing really to recommend. use a Philips
carbon pot, till you get something better.
Chassis here you are really on your own.
use your ingenuity.
Transformers Power, chokes, output Delta, Delhi
on complexity, range from Rs.1000 to 3000.
Circuit board make your own from electrical insulating board.
mount valve sockets, then hard wire point-to-point.
Hope this gives you all a starting point.
Viren
Some suggestions on the availability of parts in India:
Valves - lots of old stock of BEL (Bharat Electronics Limited) still available. Look up your local electronics "kabadiwalla"! And old movie projector parts suppliers.
Input/driver ECC82, ECC83
6SN7 Russian and US, army surplus
Output EL84, ECL86, ECL82 (sorry, only low power)
Rectifiers GZ34, EZ81, EZ80
So, these should be available for around Rs.100 each. You'll have to import only the bigger power valves. I recommend the JJ E34L -they are very robust, and great value.
Resistors and capacitors - lots of good quality parts available.
Resistors stay with 1watt carbon film Thakor, Thermax
cheaper, sound better.
metal film gives a brittle edge to the sound.
Capacitors film caps, 0.01 to 4.7uF/400V CTR
start out with these, then add your flavour with
imported caps.
Electrolytics 22 to 100uF/450V Samwa
Korean, cheap and good
easily available, thanks to the computer/inverter industry
Hookup wire teflon insulated single or multistrand copper
check with local suppliers.
Connectors RCA, binding posts MX
there has to be a stockist in your city.
Switches/electrical Elcom an industrial supply manufacturer.
Volume pots nothing really to recommend. use a Philips
carbon pot, till you get something better.
Chassis here you are really on your own.
use your ingenuity.
Transformers Power, chokes, output Delta, Delhi
on complexity, range from Rs.1000 to 3000.
Circuit board make your own from electrical insulating board.
mount valve sockets, then hard wire point-to-point.
Hope this gives you all a starting point.
Viren
hey-Hey!!!,
Here is a schematic. I have built or helped build half a dozen to this circuit. Output finals have run from type 1619, 1624, EL34, KT88, 4E27 and 813. I prefer high plate loads, like 10k but it has also done well with 6k6 a-a and 6L6GC( it's also done well with 10k 6L6's).
It is a design without loop negative FB. It is not a 'no NFB' design, instead it is all on the front side of the output TX and only needs two stages.
cheers,
Douglas
Here is a schematic. I have built or helped build half a dozen to this circuit. Output finals have run from type 1619, 1624, EL34, KT88, 4E27 and 813. I prefer high plate loads, like 10k but it has also done well with 6k6 a-a and 6L6GC( it's also done well with 10k 6L6's).
It is a design without loop negative FB. It is not a 'no NFB' design, instead it is all on the front side of the output TX and only needs two stages.
cheers,
Douglas
>Chassis here you are really on your own.
>use your ingenuity.
I second that suggestion. I have used both MS and wood-yes you can make a nice wooden chassis, through a halfway decent carpenter, with metal plates on top and bottom at a pretty low price.
I assumed that people were looking only at a power amp- I assumed by mistake that most people already had a preamp. Viren's point is good-you can just add on a pot. I find that my preamps give me a bit more flexibility- one of mine has a head phone amp, but having a pot is a cost effective way to start up.
Viren's other ideas are from someone who has more familiarity with such things than anyone else on this thread, and well worth keeping in mind.I know that BEL valves are available here in Bangalore, having got 5AR4 rectifier tube, and I suspect others will also be available, but quality could be suspect. I have always got my other valves from the US because I go there every year, and my sons also keep coming to India.
>use your ingenuity.
I second that suggestion. I have used both MS and wood-yes you can make a nice wooden chassis, through a halfway decent carpenter, with metal plates on top and bottom at a pretty low price.
I assumed that people were looking only at a power amp- I assumed by mistake that most people already had a preamp. Viren's point is good-you can just add on a pot. I find that my preamps give me a bit more flexibility- one of mine has a head phone amp, but having a pot is a cost effective way to start up.
Viren's other ideas are from someone who has more familiarity with such things than anyone else on this thread, and well worth keeping in mind.I know that BEL valves are available here in Bangalore, having got 5AR4 rectifier tube, and I suspect others will also be available, but quality could be suspect. I have always got my other valves from the US because I go there every year, and my sons also keep coming to India.
Re ballpark costing, there are some things that EVERYONE has to buy irrespective of when and how it gets completed.
Valves, valve holders
Transformers
Jacks/binding posts
wire
Caps/resistors
People may save some money on chassis, depending on ingenuity. I wouldn't advise any one to try breadboarding this-the voltages are way to high.
Since we dont know what the transformers will cost, I am willing to spend some time researching this a bit,when I am in Delhi next week and will discuss this with JP Singh of Delta and report back after I return home next Sunday. I am also scheduled to meet Viren Bakshi and will discuss all the possible options available to us.
We are looking at the appx bidget for the stuff excluding the chassis, and there is also the logistics of figuring out how to import the valves( EL 34s will cost about $60 for a matched quad). Once we know what is the appx price for the mains and output trannies, nailing down the rest of the costs may not be all that hard-again, it only will be appx budget
Valves, valve holders
Transformers
Jacks/binding posts
wire
Caps/resistors
People may save some money on chassis, depending on ingenuity. I wouldn't advise any one to try breadboarding this-the voltages are way to high.
Since we dont know what the transformers will cost, I am willing to spend some time researching this a bit,when I am in Delhi next week and will discuss this with JP Singh of Delta and report back after I return home next Sunday. I am also scheduled to meet Viren Bakshi and will discuss all the possible options available to us.
We are looking at the appx bidget for the stuff excluding the chassis, and there is also the logistics of figuring out how to import the valves( EL 34s will cost about $60 for a matched quad). Once we know what is the appx price for the mains and output trannies, nailing down the rest of the costs may not be all that hard-again, it only will be appx budget
A moral boost for my DIY tube Indian friends. Actually this was not made by me. This was partially made by my friend’s father in 1960’s. He never completed it. Preamp section was using EF86 and the power amp ECL86. I slightly re-engineered by changing the preamp to ECC83 tubes, which I bought from e-bay. I don’t think so it is a very high end configuration. But I liked very much. I definitely liked the sound. Indeed the sound is different from solid state devices. I am very happy with the sound.
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