Moderator’s Note: the use of the name diyAudio on any product is strictly prohibited without the written consent of the site’s owner, as a result, all references to such product real or imagined will be removed.Dear Friends,
Hi!
I have been following various threads at DIYAUDIO. I was very happy to find a keen group here making its presence felt worldwide.
I wanted a power amp, unfortunately Indian manufacturers are very few and the amps are available ex stock only at few places. Imported quality stuff was beyond my pocket, Chinese stuff I was not interested to put money in. Looking at various options I came across some excellent discussions on Diyaudio. It was noticed that we had limited options in case of drivers but when it came to amplifier, components and other hardware we were in much better position .
Tarun has already done most of the legwork in finding us a good source of cabinets, knobs and PCB. Net is full of excellent designs. We at DIY have one of the best brains available to discuss and seek guidance.
I feel a high end amp project will be of interest to most of us. A mention about the project on another popular thread has bought very enthusiastic response from many of my friends. A group project will be beneficial to all those involved mainly in sourcing of components, avoiding pitfalls and to sustain our interest to its end.
I have short listed my requirements and would be taking steps to fulfill them,
I seek your co-operation in creation of an equipment we all can be proud of having DIYed .
Thanks and regards
Rahul
Hi! Vivek
I have identified 3 broad categories that fullfill most of our demand:
1) High end :This broadly includes designs like Class A, excellent Pass lab schematics and tube amps. Outout power max 25W.
2) High power amp for our sub and other ocassions. Design like one from Aussie amp, Randy Salones designs and others in range of 200-250W.
3)Medium power designs of 60-80W, like the AKSA kit.
I suggest we pick one good design and move towards its completion.
I look forward to all your comments and possibly photocopy of documention of other good designs so that we may be able to get their boards made here in India.
Regards
Rahul.
I have identified 3 broad categories that fullfill most of our demand:
1) High end :This broadly includes designs like Class A, excellent Pass lab schematics and tube amps. Outout power max 25W.
2) High power amp for our sub and other ocassions. Design like one from Aussie amp, Randy Salones designs and others in range of 200-250W.
3)Medium power designs of 60-80W, like the AKSA kit.
I suggest we pick one good design and move towards its completion.
I look forward to all your comments and possibly photocopy of documention of other good designs so that we may be able to get their boards made here in India.
Regards
Rahul.
Hi,
The project sounds good. To begin how are we going to protect the IP of the designers. The AKSA design is not available as a pcb. The only other I know which is reasonably priced for us here, in India & still does not infringe on IP is the Rod Elliot design. He sells the design & the PCB. So why don't we look at options that allow us to do such a thing.
All the other parts can be sourced locally, including the tranistsors, from rsindia.
cheers,
sunil
The project sounds good. To begin how are we going to protect the IP of the designers. The AKSA design is not available as a pcb. The only other I know which is reasonably priced for us here, in India & still does not infringe on IP is the Rod Elliot design. He sells the design & the PCB. So why don't we look at options that allow us to do such a thing.
All the other parts can be sourced locally, including the tranistsors, from rsindia.
cheers,
sunil
Hi!
Good points Sunil.
As far as IP is concerned we need to take care while selection of the design. We go ahead only with those whose schematics are published and intended to be assembled by DIYers. This leaves us with few very good choices.
a) ESP and Nelson Pass.
b) Slone designs
c) Aussie amps
d) Elektor designs
e) JLH ckts.
Maybe few more. I seek more choices in this regard.
At present it is more important that we concentrate on one particular design. Important criteria while selection should also be the price to performance ratio as well as easy availability of components.
A single sided PCB. As it can be easily made in any city and I can always do the layout from schematics.
Least not we spend months collecting parts and project turn into 'Birbal ki Khichadi'.
My requiremnets have me leaning a bit towards Aussie amps N channel MOSFET Power amp design. Cause:
a)Simple single sided board
b)Good power, good references.
c)Cheap easily available MOSFET and rest of the components.
d)Guru Antony is there on Forum to help out. In fact he has lot of encouragement for people making their own layout of his designs.
Only thing lacking in this design is protection, an addon unit will be needed.
Himanshu you can always split the project into 2 parts
one make the amp and another do the SMPS. There are few designs of SMPS I would look for them. There are few sources of ferrites also.
It will be helpful if all my friends give their opinion on the subject so we can move ahead with the project.
Regards
Rahul
PS: Also checkout our thread:
http://www.diyaudio.com/forums/showthread.php?s=&postid=350124#post350124
For my post on MOSFET availibility.
Good points Sunil.
As far as IP is concerned we need to take care while selection of the design. We go ahead only with those whose schematics are published and intended to be assembled by DIYers. This leaves us with few very good choices.
a) ESP and Nelson Pass.
b) Slone designs
c) Aussie amps
d) Elektor designs
e) JLH ckts.
Maybe few more. I seek more choices in this regard.
At present it is more important that we concentrate on one particular design. Important criteria while selection should also be the price to performance ratio as well as easy availability of components.
A single sided PCB. As it can be easily made in any city and I can always do the layout from schematics.
Least not we spend months collecting parts and project turn into 'Birbal ki Khichadi'.
My requiremnets have me leaning a bit towards Aussie amps N channel MOSFET Power amp design. Cause:
a)Simple single sided board
b)Good power, good references.
c)Cheap easily available MOSFET and rest of the components.
d)Guru Antony is there on Forum to help out. In fact he has lot of encouragement for people making their own layout of his designs.
Only thing lacking in this design is protection, an addon unit will be needed.
Himanshu you can always split the project into 2 parts
one make the amp and another do the SMPS. There are few designs of SMPS I would look for them. There are few sources of ferrites also.
It will be helpful if all my friends give their opinion on the subject so we can move ahead with the project.
Regards
Rahul
PS: Also checkout our thread:
http://www.diyaudio.com/forums/showthread.php?s=&postid=350124#post350124
For my post on MOSFET availibility.
Hi Rahul,
1. Most Pass design will require a 'scope to setup. Something that I suspect many of us don't have.
2. What is this Aussie Amp? Can I see a schematic somewhere?
3. Have you investigated the Leach Low TIM Amp? Lots of nice power.
4. JLH is a simple shot at building a nice high-end amp. All parts are easily available
Finally, how are we going to collaborate on this? A collective searching/buying of parts is one aspect. PCB's, as you have said correctly, can be made in any city or homebrewed. But it will be helpful to have a group PCB order.
If its tubes then I can organise some components.
Lets do it !!
1. Most Pass design will require a 'scope to setup. Something that I suspect many of us don't have.
2. What is this Aussie Amp? Can I see a schematic somewhere?
3. Have you investigated the Leach Low TIM Amp? Lots of nice power.
4. JLH is a simple shot at building a nice high-end amp. All parts are easily available
Finally, how are we going to collaborate on this? A collective searching/buying of parts is one aspect. PCB's, as you have said correctly, can be made in any city or homebrewed. But it will be helpful to have a group PCB order.
If its tubes then I can organise some components.
Lets do it !!
Hi!
Ashok as I was saying the choice would depend upon our requirements. Many Pass designs and JLH are biased for class A. No doubt for high end applications we would be hard pressed for better ckt. I remember studying JLH PCB sometime back, it is very nice and compact But for high power and possibilty of doubling up as sub amp we have to look at other designs.
When we go for high power levels Leach is very good but I felt it would be bit difficult to source NPN and PNP matched pairs specially considering group project. It is pretty difficult to get anything apart from TV, Tape ,CD,VCD and Invertor components in mkt. Similar is the situation at Delhi the quantity should be bulk only then shopkeeper will take some interest but forget about matched transistors.
Herein lies the beauty of N channel Mosfet design there are vast number of devices available. One type of transistor makes sourcing and matching easy also it gets good discount.
The site for this amp is:
http://www.aussieamplifiers.com/n-channe.htm
It appears manual downloading is disabled hence I am attaching a zip of schematics from my archive. Ashok you will also notice bare minimum of test instruments required.
While on topic I also suggest having a look at :
http://www.diyaudio.com/forums/showthread.php?s=&threadid=19209&goto=nextoldest
The layout by Pelle is something I am thinking in terms of.
Designer Anthony Holton appears to have a very constructive attitude towards people using their PCB layout for his ckt designs.
Contd.....
Ashok as I was saying the choice would depend upon our requirements. Many Pass designs and JLH are biased for class A. No doubt for high end applications we would be hard pressed for better ckt. I remember studying JLH PCB sometime back, it is very nice and compact But for high power and possibilty of doubling up as sub amp we have to look at other designs.
When we go for high power levels Leach is very good but I felt it would be bit difficult to source NPN and PNP matched pairs specially considering group project. It is pretty difficult to get anything apart from TV, Tape ,CD,VCD and Invertor components in mkt. Similar is the situation at Delhi the quantity should be bulk only then shopkeeper will take some interest but forget about matched transistors.
Herein lies the beauty of N channel Mosfet design there are vast number of devices available. One type of transistor makes sourcing and matching easy also it gets good discount.
The site for this amp is:
http://www.aussieamplifiers.com/n-channe.htm
It appears manual downloading is disabled hence I am attaching a zip of schematics from my archive. Ashok you will also notice bare minimum of test instruments required.
While on topic I also suggest having a look at :
http://www.diyaudio.com/forums/showthread.php?s=&threadid=19209&goto=nextoldest
The layout by Pelle is something I am thinking in terms of.
Designer Anthony Holton appears to have a very constructive attitude towards people using their PCB layout for his ckt designs.
Contd.....
contd...
Ashok you have rightly pointed that PCB should be done at one place this we can decide upon it can be either Mumbai or here North. My personal observation is that work quality is better at Mumbai.
On sourcing part I suggest we make a list and check out best deals in our respective town for whole lot. We then collect all stuff at one central place. Here we do the sorting and kitting and dispatch the complete package to its location by Speed post. ( Inter state often there are excise hassels with private courier.)
This way we will save time and also will not have to run after loose ends.
We can also go in for partial kit having only the PCB and non electrolytes, resistors. ie need to purchase MOSFET and arrange caps from ones stock. If we take Auusie amp as example
Components:
I suggest Master electronics at LRM ( Lajpat Rai Mkt) shop 345 for 1% MFR resistor cost is Rs12/ per 100 minimum quantity is 200pcs. If we take 25kit trial run we have 9 value that comes to Rs216 for 25 kits , Rs 9 per kit with lot of spare left.
Similarly ceramic cased wirewound can be ordered fron Vellohm. They are very reasonable and perfrmance is also good. In past I have placed small quantity orders and recived them by mail. Service is good.
For capacitors we can shortlist BC components ex Philips or Keltron both I feel are good. At Pune Mr Vilas Rabde at BC component is a helpful person specially if its hobby. Dealers are also there in all major cities. Critical values I find 1000uF160V and the main Filter caps.
Blue box type AC caps by philips can be used in zobel network and Yellow CTR and similar cap at input.
This now leaves us with the main power transformer now this I feel one should arrange locally ie get it custom made on EI cores or look for a torroidal ones. Sending them by post does not appears to be practical.
MOSFET from IR (International Rectifier) are easily available.
Looking back now I find this project quite feasible as well as enjoyable. BTW I have done some kitting in past too.
I look forward to your suggestion and co operation to get the project going.
Regards
Rahul
Ashok you have rightly pointed that PCB should be done at one place this we can decide upon it can be either Mumbai or here North. My personal observation is that work quality is better at Mumbai.
On sourcing part I suggest we make a list and check out best deals in our respective town for whole lot. We then collect all stuff at one central place. Here we do the sorting and kitting and dispatch the complete package to its location by Speed post. ( Inter state often there are excise hassels with private courier.)
This way we will save time and also will not have to run after loose ends.
We can also go in for partial kit having only the PCB and non electrolytes, resistors. ie need to purchase MOSFET and arrange caps from ones stock. If we take Auusie amp as example
Components:
I suggest Master electronics at LRM ( Lajpat Rai Mkt) shop 345 for 1% MFR resistor cost is Rs12/ per 100 minimum quantity is 200pcs. If we take 25kit trial run we have 9 value that comes to Rs216 for 25 kits , Rs 9 per kit with lot of spare left.
Similarly ceramic cased wirewound can be ordered fron Vellohm. They are very reasonable and perfrmance is also good. In past I have placed small quantity orders and recived them by mail. Service is good.
For capacitors we can shortlist BC components ex Philips or Keltron both I feel are good. At Pune Mr Vilas Rabde at BC component is a helpful person specially if its hobby. Dealers are also there in all major cities. Critical values I find 1000uF160V and the main Filter caps.
Blue box type AC caps by philips can be used in zobel network and Yellow CTR and similar cap at input.
This now leaves us with the main power transformer now this I feel one should arrange locally ie get it custom made on EI cores or look for a torroidal ones. Sending them by post does not appears to be practical.
MOSFET from IR (International Rectifier) are easily available.
Looking back now I find this project quite feasible as well as enjoyable. BTW I have done some kitting in past too.
I look forward to your suggestion and co operation to get the project going.
Regards
Rahul
Hi Rahul,
Quite interesting.
Ok. Lets decide what goal we have.
I want to build at least 2 power amps. One to drive the upper band and the, more beefier amp, to drive the bass.
For the upper band I want a Class A. I'm looking at anything between 15 to 40 watts on this.
For the lower band a Class B or AB. I've built the Leach amp in the past and can vouch that its is simple enough design.
My past experiences with MOSFETS have not been very good. Both with commercial and homebrewed. The commercial was a Pioneer that I heard at my local high-end audio shop. The homebrewed was at guy's house whose skill I admire. But I've been reading on this forum that Pass MOSFET amps are really nice. Even Rod Elliot has given in to MOSFETS. So after all they are not a bad thing it seems.
Frankly, I was not giving much thought to MOSFET. But your views are changing that and if the group build veers to the Aussieamp then you may count me in too.
Parts:
While I agree that MOSFETS (BJT's) are available in plenty, I would be wary. I have been reading on net (Rod E has an excellent article) on the dubious nature of most of these devices. He points out China and India (naturally) as sources for these counterfeits. IR devices at Rs. 45 ring an alarm. But honestly I have no idea and things could be just fine. I will trust your views on these matters.
But MOSFET/BJT prices at RS India looks nice too. You need to order intelligently for this. Caps/Rectifiers etc are priced quite ok. All MFR that I've picked up in India have steel end caps. Throw them at a magnet and the stick. But the ones I rcvd from RS have no such issues. And they have clear leads to unlike the carbon coated one we get locally.
Aur ek source "phokat ka namoona" hai. Agar mei english pe likhun to iss forum ke finangi kaafi hulla karenge. Off list discussions karte hain iss barre mei.
Now coming to Chassis. Tarun has located an excellent source for the same. But if we are going to build a JLH or Aussi am then I believe we have to build our own chassis. Quite a simple thing actually. If required I can build them for this group.
So lets start by deciding on the following important issues:
1. Which amp or amps
2. How many builder
3. What skill set each of us can bring to this group effort.
Regards
NB: I'm also requesting amp guru Anshu to have a look at this thread.
Quite interesting.
Ok. Lets decide what goal we have.
I want to build at least 2 power amps. One to drive the upper band and the, more beefier amp, to drive the bass.
For the upper band I want a Class A. I'm looking at anything between 15 to 40 watts on this.
For the lower band a Class B or AB. I've built the Leach amp in the past and can vouch that its is simple enough design.
My past experiences with MOSFETS have not been very good. Both with commercial and homebrewed. The commercial was a Pioneer that I heard at my local high-end audio shop. The homebrewed was at guy's house whose skill I admire. But I've been reading on this forum that Pass MOSFET amps are really nice. Even Rod Elliot has given in to MOSFETS. So after all they are not a bad thing it seems.
Frankly, I was not giving much thought to MOSFET. But your views are changing that and if the group build veers to the Aussieamp then you may count me in too.
Parts:
While I agree that MOSFETS (BJT's) are available in plenty, I would be wary. I have been reading on net (Rod E has an excellent article) on the dubious nature of most of these devices. He points out China and India (naturally) as sources for these counterfeits. IR devices at Rs. 45 ring an alarm. But honestly I have no idea and things could be just fine. I will trust your views on these matters.
But MOSFET/BJT prices at RS India looks nice too. You need to order intelligently for this. Caps/Rectifiers etc are priced quite ok. All MFR that I've picked up in India have steel end caps. Throw them at a magnet and the stick. But the ones I rcvd from RS have no such issues. And they have clear leads to unlike the carbon coated one we get locally.
Aur ek source "phokat ka namoona" hai. Agar mei english pe likhun to iss forum ke finangi kaafi hulla karenge. Off list discussions karte hain iss barre mei.
Now coming to Chassis. Tarun has located an excellent source for the same. But if we are going to build a JLH or Aussi am then I believe we have to build our own chassis. Quite a simple thing actually. If required I can build them for this group.
So lets start by deciding on the following important issues:
1. Which amp or amps
2. How many builder
3. What skill set each of us can bring to this group effort.
Regards
NB: I'm also requesting amp guru Anshu to have a look at this thread.
Re: help for car amplifier designing
You're in the wrong forum. Go through the car audio forums; there are many of them around, and they are very active. Car audio is a specialised art+science.himanshuraval said:i am also designing a car amplifier for my own car so if you any have a complate amplifier+smpsd designs with pcd design so please help me
Want to try Randy Slone's ultra-low-distortion amp?
I have been strongly influenced by Randy Slone's books and designs. And he has learned a lot from JLH and Doug Self. And I've been looking for a top-quality design which will have about as much power output as is needed for normal home audio, but no more. (If you go up the power curve, the absolute levels of distortion usually worsen. So an optimal power output figure is needed.)
I don't want to go for Class A, because I'm a beginner and I want to build an amp without messing around with all that heat dissipation. So my second amp will be the JLH 1996 (modified) design (with 2003 mods). But before that, I want to try my hands at a reasonable sized top-class amp design which even I can build. It is possible that many of you may have similar goals.
After going through all the sites that I've discovered or been referred to, I've finally come down to a BJT amp of modest power output (about 80W RMS), with ultra low distortion and output current limiting. The component count is low enough for me to hope that I'll be able to build it without too much trouble. The size of the PCB is about 6"x4" as given in Randy's book, and I'm quite sure we can even design our own PCB if we want to. It uses
)
Angshu has built the Doug Self Blameless amp, and it sounds outstanding. I dare say that these amps may be able to compete with Hugh's AKSA amp, sans the benefit of his fine tuning and premium grade components.
I'm totally in for this design. I want to make this one.... I've studied many, many alternatives, and for a variety of reasons, I feel that this is the one I want to try first, before I try anything else.
Those of you who want to build high-power systems may consider building a bi-amped or tri-amped system with this amp as a building block. For a high-power subwoofer, it may be necessary to use some other amp with 200W power output. Something like the Opti-MOS amp may be a better idea in that case. However, for the mids and highs, this BJT amp may give better performance than the Opti-MOS, in a multi-amped setup.
If you guys want to work on this amp, I can get the (single-sided) PCBs made here on 2-ounce FR4 board. Someone will have to design the PCB layout first, of course. And it may not be feasible to use the free version of Eagle that I have... it limits board size to 3.2"x4".
What do you think?
I don't see any issue in IP infringement if we build our own amp with our own PCB, for our personal (i.e. non-commercial use) based on a schematic which has been published in a book or on the Internet.sunil said:
I have been strongly influenced by Randy Slone's books and designs. And he has learned a lot from JLH and Doug Self. And I've been looking for a top-quality design which will have about as much power output as is needed for normal home audio, but no more. (If you go up the power curve, the absolute levels of distortion usually worsen. So an optimal power output figure is needed.)
I don't want to go for Class A, because I'm a beginner and I want to build an amp without messing around with all that heat dissipation. So my second amp will be the JLH 1996 (modified) design (with 2003 mods). But before that, I want to try my hands at a reasonable sized top-class amp design which even I can build. It is possible that many of you may have similar goals.
After going through all the sites that I've discovered or been referred to, I've finally come down to a BJT amp of modest power output (about 80W RMS), with ultra low distortion and output current limiting. The component count is low enough for me to hope that I'll be able to build it without too much trouble. The size of the PCB is about 6"x4" as given in Randy's book, and I'm quite sure we can even design our own PCB if we want to. It uses
- 2N5551/5401 small-signal transistors
- 2SB669/2SD649 driver transistors (high-voltage, low-capacitance versions of the old familiar BD139/140 class of devices)
- 2SA1943/2SC5200 BJT flat-pack power transistors. Will work equally well with the Motorola MJ15003/15004 TO3 devices.
- supply rails of +/-42V
)Angshu has built the Doug Self Blameless amp, and it sounds outstanding. I dare say that these amps may be able to compete with Hugh's AKSA amp, sans the benefit of his fine tuning and premium grade components.
I'm totally in for this design. I want to make this one.... I've studied many, many alternatives, and for a variety of reasons, I feel that this is the one I want to try first, before I try anything else.
Those of you who want to build high-power systems may consider building a bi-amped or tri-amped system with this amp as a building block. For a high-power subwoofer, it may be necessary to use some other amp with 200W power output. Something like the Opti-MOS amp may be a better idea in that case. However, for the mids and highs, this BJT amp may give better performance than the Opti-MOS, in a multi-amped setup.
If you guys want to work on this amp, I can get the (single-sided) PCBs made here on 2-ounce FR4 board. Someone will have to design the PCB layout first, of course. And it may not be feasible to use the free version of Eagle that I have... it limits board size to 3.2"x4".
What do you think?
Fake MOSFETs and other stories
The price for this in USD 7.80/ea, in quantities of one hundred, from www.mouser.com. All other sources I checked have prices in this price range. It is totally unbelievable that any legal reseller of the genuine item will be able to import the device, pay Customs duty and shipping costs, and bring down the cost to USD 1.00/ea (i.e. Rahul's quoted price of about Rs.45/ea). I'm sure there can be differences of opinion on this, but when it comes to my personal choice, my mind is made up; I'll not trust these devices at these prices.
I have studied price variations and arbitrage opportunities in transistors and chips for almost the last two years as part of my hobby, just to see what's available where, how much volume discounts can one get if one has the budgets, etc. All my R&D tells me that a volume purchaser in India will be able to get the genuine items from overseas, cover his costs, and resell in India at about the same price as Digikey/Farnell/Mouser can sell in ones and two abroad. Any price advantage you get by ordering a thousand (no Indian reseller will order a million transistors) will be offset by the import duties and shipping costs. This is the rule of thumb I've arrived at after a lot of correlation of literally a hundred odd data points. Therefore, if US retailers sell this device in ones and two for USD 8.00, the Indian retailer will have to sell at about the same price or higher, even after accounting for large bulk orders.
This brings me back to a suspicion I've been having all along on this thread: we need to import the key components of our Indian group-build amp project. That's the only way to get genuine high-cost devices. If we can freeze on the amp, and the devices, soon, we can take advantage of some of our members' overseas trips.
BTW, the MJ15003/15004 devices, and the 2SA1943/2SC5200 devices are both widely used by a lot of high-end BJT amps. Even the AKSA uses the 2SA/2SC devices, I believe. And among MOSFETs, the 2SK1058/2SJ162 devices appear to be the consensus devices for high-quality amps. Rod Elliott and Randy Slone both use only these devices for all their MOSFET amps. So maybe we'll be safe if we stick to these devices... our investment will be protected, so to speak, whatever amp we build. We can even use these for the JLH Class A, or the Leach Low-TIM amp.
What do you say?
Ashok, I too had a lot of doubts about Rahul's pricing. So I did some R&D. You are welcome to go to www.findchips.com, type in "IRF250" and look for resellers who are selling it. The device is a 200V N-channel HEXFET device, which, in TO3 packaging, can deliver up to 30A. Rahul, please correct me if I'm wrong.corbato said:
The price for this in USD 7.80/ea, in quantities of one hundred, from www.mouser.com. All other sources I checked have prices in this price range. It is totally unbelievable that any legal reseller of the genuine item will be able to import the device, pay Customs duty and shipping costs, and bring down the cost to USD 1.00/ea (i.e. Rahul's quoted price of about Rs.45/ea). I'm sure there can be differences of opinion on this, but when it comes to my personal choice, my mind is made up; I'll not trust these devices at these prices.
I have studied price variations and arbitrage opportunities in transistors and chips for almost the last two years as part of my hobby, just to see what's available where, how much volume discounts can one get if one has the budgets, etc. All my R&D tells me that a volume purchaser in India will be able to get the genuine items from overseas, cover his costs, and resell in India at about the same price as Digikey/Farnell/Mouser can sell in ones and two abroad. Any price advantage you get by ordering a thousand (no Indian reseller will order a million transistors) will be offset by the import duties and shipping costs. This is the rule of thumb I've arrived at after a lot of correlation of literally a hundred odd data points. Therefore, if US retailers sell this device in ones and two for USD 8.00, the Indian retailer will have to sell at about the same price or higher, even after accounting for large bulk orders.
This brings me back to a suspicion I've been having all along on this thread: we need to import the key components of our Indian group-build amp project. That's the only way to get genuine high-cost devices. If we can freeze on the amp, and the devices, soon, we can take advantage of some of our members' overseas trips.
BTW, the MJ15003/15004 devices, and the 2SA1943/2SC5200 devices are both widely used by a lot of high-end BJT amps. Even the AKSA uses the 2SA/2SC devices, I believe. And among MOSFETs, the 2SK1058/2SJ162 devices appear to be the consensus devices for high-quality amps. Rod Elliott and Randy Slone both use only these devices for all their MOSFET amps. So maybe we'll be safe if we stick to these devices... our investment will be protected, so to speak, whatever amp we build. We can even use these for the JLH Class A, or the Leach Low-TIM amp.
What do you say?
Yes, that'd be great, if you can bribe him to participate. His current bribery rates are very high.
Hi Tarun,
A Single Stage, Single Ended MOSFET design would appear to be an ideal Class A project for the first timer. MOSFET's are transconductance devices and Class A is the way to go. I think 15 watts from a suitable, single MOSFET rated at approx 175 watts/15A is a realistic thing. I'm sure there would be schematics floating around in the net with these goals.
But as I posted earlier, my experience with MOSFET has not been outstanding. I somehow like the sound of BJT's and therefore my first choice will be the JLH.
D.Self Blameless Amp has its own followers. I saw one guy's website (quite a hi end freak) who had built tri-amped rig around D.Self. And Angshu swears by his BA. So its is worthwhile to consider that. Yes.
Bi-amping is the ultimate goal here. At least for me. My Valve amps are fine. But I need another setup.
What are we thinking in terms of:
1. Linestage
2. Active XO (If Bi-amping)
Being a tube guy my choice obviously is that way. I'm not too sure if others would be that enthusiastic. However, if at all you guy's want to investigate this route then let me assure you that Tubes aren’t that dangerous or difficult as it would seem.
A Single Stage, Single Ended MOSFET design would appear to be an ideal Class A project for the first timer. MOSFET's are transconductance devices and Class A is the way to go. I think 15 watts from a suitable, single MOSFET rated at approx 175 watts/15A is a realistic thing. I'm sure there would be schematics floating around in the net with these goals.
But as I posted earlier, my experience with MOSFET has not been outstanding. I somehow like the sound of BJT's and therefore my first choice will be the JLH.
D.Self Blameless Amp has its own followers. I saw one guy's website (quite a hi end freak) who had built tri-amped rig around D.Self. And Angshu swears by his BA. So its is worthwhile to consider that. Yes.
Bi-amping is the ultimate goal here. At least for me. My Valve amps are fine. But I need another setup.
What are we thinking in terms of:
1. Linestage
2. Active XO (If Bi-amping)
Being a tube guy my choice obviously is that way. I'm not too sure if others would be that enthusiastic. However, if at all you guy's want to investigate this route then let me assure you that Tubes aren’t that dangerous or difficult as it would seem.
Do you think there are Pass designs which fit this description?corbato said:
And Class A or no Class A, I'd be interested in a simple amp with really good sonics, as a first high-end project for myself. If Rod had generously given away the values of the components for his new MOSFET amp, I'd have been willing to try that one too. Even the P3A is a good amp, but if I go towards the P3A, I don't see why one shouldn't go a step more and do either the Blameless or Randy's ultra-low-distortion amp.
I would personally prefer this sort of power rating only for a tweeter in a 2-way or 3-way setup. I think the mid needs more power, specially if like me, you want to have one mid handling everything from about 150Hz to say, 3KHz. But then your intended use for the Class A is precisely the way I'd have done it... confine it to the higher reaches. Let the sheen of Asha's voice come out A-class.
(****! I think today is the Day of PJs for me. Sorry!)Yes, I think that this Slone BJT amp too can be an excellent building block. Even for woofers, if you build more than one woofer per speaker, you can drive each driver with a separate amp, and you'll have more than enough power that way.
Strangely, I too have reached a point where I want to build active xo instead of passive. (It's all Angshu's fault, really.) Hence the need for really high-quality but simple to build amps, which I can build half a dozen at a time.
I guess some will want the minimalist volume-pot-only approach, and others will want a conventional preamp (I'm in the latter camp, with bypassable tone controls). If others want to go my way, my PCB design can be replicated rapidly. Roadkill of B'lore has a preamp based on the LM1036, I think, which he can probably make avaiable for another approach to linestaging.
Want to do do LR4 based on dual-opamp chips? (This is a question to non-tubers, not to you.
) (Hey! This is a good term for you. "Tuber."!! ) I think LR4 is about the most mainstream and reliable approach to active xo, specially for first-timers like me.My answer for now is very clear... I don't want to try them for my first couple of projects. Let me get a few reliable, inexpensive amps completed first.
Hi!
Tarun I would like to point to a slight error on my part the MOSFET i was telling are IRFP250 these are Plastic packaged probably package is called TO247.
I confirmed again in mkt and one the reputed shop has quoted at Rs45/, IRFP460 Rs100/ and IRF540 Rs18/ all in genuine IR packing. You are right about IRF250 it is indeed TO3 metal pack and more expensive. The IRFP variant is very popular with UPS manufacturers. I suggest just giving a call to any local shop there and we all can have confirmed price of these MOSFET at Mumbai.I am sure they would be near about my quoted price.
Self and JLH are world class designers, the THD figures are realy a proof of their mastery of the art. I doubt that we require such figures for a raw power amp.
Tarun I would look for the numbers you have mentioned for outputs I have not used them before, I am not very confident about availibility of matched complimentry pairs BJTs for output. You will notice this was one of the reason I have even avoided complimentry MOSFET design.
Using IRFP250 appeared practical hence I suggested the same. I have now noticed that Aussie design has already been made by our another friend here:
http://www.diyaudio.com/forums/showthread.php?threadid=3533
Ashok you are right a single ended MOSFET design from PASS can be considered very good as a beginer project. I have made many SE amplifier using mosfet for RF and feel they work very well and can be aasembled very easily. Heatsink sourcing I feel would not be as difficult as sourcing exotic output devices.
As you have rightly pointed we all would need two type of amps. I fully agree to go with either a JLH or SE type from Pass for the highs and a hefty one for low I am keeping all options open but for now Auusie amp still appears attractive to me considering all factors for the beefy amp.
Tarun for PCB I can do unlimited size here on EasyPC an award winning software, many friends also use ORCAD can request them for layout.
Ah yes abt the phukat method a group of us are known over the radio as Bravo , Oscar , Lima (BOL) Beggars- on -line. We got good samples for very high end projects even a DDS (Direct digital synthesis) chips.
I request first we shortlist class and amp power before we proceed.
Regards
Rahul
PS: here I have scope and other instruments for testing etc.
Tarun I would like to point to a slight error on my part the MOSFET i was telling are IRFP250 these are Plastic packaged probably package is called TO247.
I confirmed again in mkt and one the reputed shop has quoted at Rs45/, IRFP460 Rs100/ and IRF540 Rs18/ all in genuine IR packing. You are right about IRF250 it is indeed TO3 metal pack and more expensive. The IRFP variant is very popular with UPS manufacturers. I suggest just giving a call to any local shop there and we all can have confirmed price of these MOSFET at Mumbai.I am sure they would be near about my quoted price.
Self and JLH are world class designers, the THD figures are realy a proof of their mastery of the art. I doubt that we require such figures for a raw power amp.
Tarun I would look for the numbers you have mentioned for outputs I have not used them before, I am not very confident about availibility of matched complimentry pairs BJTs for output. You will notice this was one of the reason I have even avoided complimentry MOSFET design.
Using IRFP250 appeared practical hence I suggested the same. I have now noticed that Aussie design has already been made by our another friend here:
http://www.diyaudio.com/forums/showthread.php?threadid=3533
Ashok you are right a single ended MOSFET design from PASS can be considered very good as a beginer project. I have made many SE amplifier using mosfet for RF and feel they work very well and can be aasembled very easily. Heatsink sourcing I feel would not be as difficult as sourcing exotic output devices.
As you have rightly pointed we all would need two type of amps. I fully agree to go with either a JLH or SE type from Pass for the highs and a hefty one for low I am keeping all options open but for now Auusie amp still appears attractive to me considering all factors for the beefy amp.
Tarun for PCB I can do unlimited size here on EasyPC an award winning software, many friends also use ORCAD can request them for layout.
Ah yes abt the phukat method a group of us are known over the radio as Bravo , Oscar , Lima (BOL) Beggars- on -line. We got good samples for very high end projects even a DDS (Direct digital synthesis) chips.
I request first we shortlist class and amp power before we proceed.
Regards
Rahul
PS: here I have scope and other instruments for testing etc.
Hi, Rahul.Rahul said:
Now that you've made things clearer, I was expecting less confusion. But in fact, I'm even more confused by what I just saw. I found that IRFP250 is a device described by different manufacturers as being different devices. For instance, some claim it's a MOSFET, some claim it's a HEXFET. Some say it has 30A current rating, and others say 20A. I'm simply not comfortable dealing with any device till I clearly understand what people mean when they use this part number. If you want to see what I mean, just go to www.findchips.com, type in "IRFP250", and see what comes up. Digikey has three devices with this part number, one made by STMicroelectronics ($2.81), and two made by Int'l Rectifier (prices: $5.90 and $3.33). All have the TO247 packaging. Going down the page and looking at the other quotes from other sellers, I see prices ranging from $1.57 (if you buy in hundreds) to $7.57. And they are made by at least three manufacturers: STM, Fairchild, and IRF. Which one would you choose? Me beginner... I'll just stick to BJT.
I'm quite sure you've asked a reputed vendor, but you will have to read (or perhaps re-read) Rod Elliott's article about counterfeit semiconductors to really understand that there's no such thing as "reputed" or "reliable" in this business. And this is not a comment on India alone; it's a worldwide racket. It needs sophisticated clean-room labs and fab houses to create the fakes.
Therefore, there's nothing to be gained by my checking Mumbai prices. It doesn't matter what the Mumbai prices are.... if they are as inexpensive as what you'd said, they're guaranteed to be fakes. If they are expensive, then there's no assurance that they're genuine, but at least one can try. If you ask me, I'd simply not buy even a single piece from any Indian shop.... I'd try to order either direct from the manufacturer (IRF sells directly to individuals) or from a big int'l reseller like Allied Electronics or Digikey. Rod Elliott tells you about fakes sold by Digikey Canada, incidentally.
I'm now no more sure what you mean by "raw power amp." Can you please explain? Are there different kinds of power amps?
This matching of OPS devices is a bit of a controversial topic, somewhat like going for expensive Hovland Musicaps for a "cleaner sound." Randy Slone categorically says he's never matched OPS devices for his amps, and all his super-low THD measurements have been made without any such matched pairs. He says that matched pairs are only needed when you make long-tailed pairs for input stages. His opinion is that any high-GNFB power amp will be able to totally override any differences in hfe of OPS devices because of the GNFB. So, if you're building a zero-feedback power amp, maybe you'll need to match the OPS devices.
Hence, don't worry about that, would be my suggestion.
Can you please give me a URL to schematics and other info? I've briefly looked though www.passdiy.com but have not found any specific details. And if we are talking simple amps, what about the DoZ (Death of Zen) amp from Rod Elliott?
I fully agree on heatsinks... they're available in L.Road here. But even OPS devices can be easily brought in by any one of us who goes abroad. You can even directly order them from, say OnSemi (you'll get MJ15003/4 from there), ask them for courier delivery to India, and pay Customs. One of my friends got 25 each of these devices this way. And since this was OnSemi's sample program, he paid only for the shipping, not the devices.
The best thing about a group-build is that we can source the components through a group-buy and pool together our resources. Let's not be held to ransom by the L.Road class of resellers... let's do something better. (Better does not mean more costly.)
Sigh.... I wanted to get Vutrax up and running (Vutrax and Eagle are the only two good eCAD packages on the OS we use here). Vutrax' free version has no limit on board size, so it would be ideal even for large power amps like the OptiMOS. But there's some system mismatch, and I'll have to upgrade my laptop OS first before Vutrax works on it.
Till then, I'm jealous of you. Hello,
I like Tarun's idea of going active X/O. I'm not very technical & can't understand the lingo you speak. I do know what class A sounds like.
I have put together a 3-way active X/O & am currently looking at a tweeter amp. I'm looking at the Aksa or a Rod Elliot design. If we are looking at a group thing why don't we all go active, low power, multi-amp & gently nudge the neighbours.
cheers,
sunil
I like Tarun's idea of going active X/O. I'm not very technical & can't understand the lingo you speak. I do know what class A sounds like.
I have put together a 3-way active X/O & am currently looking at a tweeter amp. I'm looking at the Aksa or a Rod Elliot design. If we are looking at a group thing why don't we all go active, low power, multi-amp & gently nudge the neighbours.
cheers,
sunil
Has anyone considered the Crescendo or the mini Crescendo? This is however not as simple as Holton's N channel amp or the P3A.
One more thing all of us need to look into carefully is the speaker DC protection. We in India always have a doubt about the quality of the o/p devices. If they fail, your speakers are history. This should be looked into also.
But again, as I understand it, adding a relay-based protection circuit poses its own problems. We need a good relay in the first place and are protection circuits not known to introduce distortion.
Vivek
One more thing all of us need to look into carefully is the speaker DC protection. We in India always have a doubt about the quality of the o/p devices. If they fail, your speakers are history. This should be looked into also.
But again, as I understand it, adding a relay-based protection circuit poses its own problems. We need a good relay in the first place and are protection circuits not known to introduce distortion.
Vivek
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