Hey the DX original was my first DIY SS amp... The DX HDII board can be used to construct the orinal one too with a few minor part sustitutions/ommissions.
My previous experience was also chipamps...... worthy training ground. I won't claim to be on top of the DX amp seen from a macroscopic point of view, but through building it (and finding my errors and blown components), I learned enough to fix many old solidstate amps now, by focusing on it as little modules.
The silkscreen will at least make it less likely that you will make the same mistakes I did.
Plus the group of people that can pitch in with advice is steadily growing...... We try to keep things practical, and keep the scientists at a good distance...those guys who listen with scopes instead of ears...
The realy smart ones give us advice that anyone can understand...
My previous experience was also chipamps...... worthy training ground. I won't claim to be on top of the DX amp seen from a macroscopic point of view, but through building it (and finding my errors and blown components), I learned enough to fix many old solidstate amps now, by focusing on it as little modules.
The silkscreen will at least make it less likely that you will make the same mistakes I did.
Plus the group of people that can pitch in with advice is steadily growing...... We try to keep things practical, and keep the scientists at a good distance...those guys who listen with scopes instead of ears...
The realy smart ones give us advice that anyone can understand...
Sorry guys I will have to get back to you later with answers, hectic morning... yesterday was public holiday.....
Just received some new written quotes from the guys that quoted me last time... I asked for quotes on both 1 and 2 oz boards, based on our new numbers... looks like we can now get the 2oz boards for about the price I was qouted on 1oz originaly...
Waiting for written confirmation on the transactional cost part, hopefully will also receive this today. Then I can give you firmer prices. I think for the less than $4 per set diffirence it is well worth it.
Watch this spot.
Just received some new written quotes from the guys that quoted me last time... I asked for quotes on both 1 and 2 oz boards, based on our new numbers... looks like we can now get the 2oz boards for about the price I was qouted on 1oz originaly...
Waiting for written confirmation on the transactional cost part, hopefully will also receive this today. Then I can give you firmer prices. I think for the less than $4 per set diffirence it is well worth it.
Watch this spot.
Thank you folks....to all of you.... Dx Corporation thank you all by the nice
preference (Dx Corporation is only a game, kidding)....but we do not pay to dream.
I see that many folks are interested...i feel very good, you are filling my heart with a very nice feeling, the one we have when we contribute with others...the best feeling i think.
Ed de La Fontaine is an old and good friend...thank you...you are also in my heart...you are very positive and strongly appreciated.
Nordic...you are running very well this group buy....of course i have to thank you and will order a raise into your payment from the Corporation.
Thank you Nordic....excelent work.
I am sure you will appreciate the sonics folks...enjoy the nice sonics of this little amplifier that will provide you hours of joy and happyness.
regards
Carlos
.....................................................................................................
Rabbitz, Greg and other aussies
Were perceived into this group buy.... thank you very much...you know i love you all Aussie friends.
Nice people.... very nice people.
regards,
Carlos
preference (Dx Corporation is only a game, kidding)....but we do not pay to dream.
I see that many folks are interested...i feel very good, you are filling my heart with a very nice feeling, the one we have when we contribute with others...the best feeling i think.
Ed de La Fontaine is an old and good friend...thank you...you are also in my heart...you are very positive and strongly appreciated.
Nordic...you are running very well this group buy....of course i have to thank you and will order a raise into your payment from the Corporation.
Thank you Nordic....excelent work.
I am sure you will appreciate the sonics folks...enjoy the nice sonics of this little amplifier that will provide you hours of joy and happyness.
regards
Carlos
.....................................................................................................
Rabbitz, Greg and other aussies
Were perceived into this group buy.... thank you very much...you know i love you all Aussie friends.
Nice people.... very nice people.
regards,
Carlos
Attachments
Carlos- You much too modest
Carlos
Your design is very good. I have a niggling suspicion that when the amp is playing into a easy load it going to sound much better than 90% of my commercial amps. The only problem I have is that I suspect that my speakers occasionally drops to a very low impedance.
Despite my concern I am going to build your amp. I shudder what will happen if one uses very high-end parts. With so few parts it crazy not to use the very best parts you can find.
I hope that you can make some money out of your design for it is incredible jumpstart to high-end audio for any budding audiophile on a budget.
I wish you and Nordic well with your endevours.
Jozua
Cape Town
South Africa
Carlos
Your design is very good. I have a niggling suspicion that when the amp is playing into a easy load it going to sound much better than 90% of my commercial amps. The only problem I have is that I suspect that my speakers occasionally drops to a very low impedance.
Despite my concern I am going to build your amp. I shudder what will happen if one uses very high-end parts. With so few parts it crazy not to use the very best parts you can find.
I hope that you can make some money out of your design for it is incredible jumpstart to high-end audio for any budding audiophile on a budget.
I wish you and Nordic well with your endevours.
Jozua
Cape Town
South Africa
Thanks for the kind words.....
I forgot to tell you, none of the components except the input pairs were matched.......
Instead of going for the huge $ components, another approach to improved performance, can be to buy larger volumes of transistors etc. and matching them as close as possible.
Like I said, just give me a shout, and I'll bring the amp over so you can test it with your own speakers, and in your own listeing room.
The group buy is, as far as am concerned, definately happening.
I will try to make a page in the site's wiki section today.
If there is a demand I can also produce PSU boards.
The schematic for the PSU will be posted on the new website, they are burried so deep in the DX thread it may take you a while to find it otherwise, in case you'd like to DIY them.
Alternatively I have another low cost PCB manufacturer useing CNC router that can make those for us at minimal extra cost....
The catch? No soldermask, no silkscreen.... but this part of the circuit don have any transistors that can be inverted, so it is not a dealbreaker... This guy is very cheap....... If we were to make the DX boards useing his product, the cost would have been about a 3rd of what it is. I'd rather you have proper 2oz boards with silkcreens than have to field faultraceing answers all day long due to a lack of silk screen, so, this option only applies to the PSU.
I know the DX thread is very long so guys may have missed the fact that the VBE multiplier (bias servo) is offboard, it is however so small and simple that I will provide you with prepared veroboard strips for simply soldering the resistor, trimpot and transistor on there.
I forgot to tell you, none of the components except the input pairs were matched.......
Instead of going for the huge $ components, another approach to improved performance, can be to buy larger volumes of transistors etc. and matching them as close as possible.
Like I said, just give me a shout, and I'll bring the amp over so you can test it with your own speakers, and in your own listeing room.
The group buy is, as far as am concerned, definately happening.
I will try to make a page in the site's wiki section today.
If there is a demand I can also produce PSU boards.
The schematic for the PSU will be posted on the new website, they are burried so deep in the DX thread it may take you a while to find it otherwise, in case you'd like to DIY them.
Alternatively I have another low cost PCB manufacturer useing CNC router that can make those for us at minimal extra cost....
The catch? No soldermask, no silkscreen.... but this part of the circuit don have any transistors that can be inverted, so it is not a dealbreaker... This guy is very cheap....... If we were to make the DX boards useing his product, the cost would have been about a 3rd of what it is. I'd rather you have proper 2oz boards with silkcreens than have to field faultraceing answers all day long due to a lack of silk screen, so, this option only applies to the PSU.
I know the DX thread is very long so guys may have missed the fact that the VBE multiplier (bias servo) is offboard, it is however so small and simple that I will provide you with prepared veroboard strips for simply soldering the resistor, trimpot and transistor on there.
Hi Jozua,
the component spacing is an issue in using "higher quality" components eg Vishay/Dale resistors etc as the PCB is small. They designed it for small tracks which is a good idea. However as mentioned before matching good transistors should be an improvement. As for the amp running into difficult loads I think it should be quiet capable but I did ask Carlos to help show us a design using 50Volts with two output pairs. Another alternative is to bi-amp which is what I am thinking of doing as the costs are very low.
Regards
Harry
PS I am glad you like the amp as I know you have a number of Krell amps to compare it to.
the component spacing is an issue in using "higher quality" components eg Vishay/Dale resistors etc as the PCB is small. They designed it for small tracks which is a good idea. However as mentioned before matching good transistors should be an improvement. As for the amp running into difficult loads I think it should be quiet capable but I did ask Carlos to help show us a design using 50Volts with two output pairs. Another alternative is to bi-amp which is what I am thinking of doing as the costs are very low.
Regards
Harry
PS I am glad you like the amp as I know you have a number of Krell amps to compare it to.
Carlos may or may not release a new version a little later on... if I can float the boat till then, I will gladly see if I can assist again.
Sadly in those thousands of posts, Carlos gave many people advice on how to build higher power versions. Doing calculations prototypes etc... yet only 2 people went as far as constructing it.
I have increased the package sizes for the matched resistors around the input pair, to accommodate other types... and will see what I can do to the ones on the feedback path before sending the boards in.
P.S. Welcome, Gert. Nice to have another South African here.
Sadly in those thousands of posts, Carlos gave many people advice on how to build higher power versions. Doing calculations prototypes etc... yet only 2 people went as far as constructing it.
I have increased the package sizes for the matched resistors around the input pair, to accommodate other types... and will see what I can do to the ones on the feedback path before sending the boards in.
P.S. Welcome, Gert. Nice to have another South African here.
Current ability
Harry
I have a 200 watt amp that has a Led display indicating the wattage output. Dont be fooled that low listening levels always means a low wattage output. On occasion I easily get 100-150 watts peaks on speakers that are claimed to be easily driven.
I suspect that the only edge the 50. clones have is their ability to stay in control with low impedance speakers -meaning that the sound remains coherent and dynamic and you get a sense of absolute control. BUT I have a niggling suspicion that i.t.o. musicality the DX is at the forefront.
After the Krell clones- I am finished with big audio projects. From then on it's low cost minimalist projects only.
My thinking now is also to build a 4 channel version that I can use for experimental work.
Nordic
Please explore the PSU board option. The neater the better.
I have a DIY Nelson Pass "Bride of Zen" pre-amp which I suspect will work very well with the DX as it is also a very simple one stage design.
Jozua
Harry
I have a 200 watt amp that has a Led display indicating the wattage output. Dont be fooled that low listening levels always means a low wattage output. On occasion I easily get 100-150 watts peaks on speakers that are claimed to be easily driven.
I suspect that the only edge the 50. clones have is their ability to stay in control with low impedance speakers -meaning that the sound remains coherent and dynamic and you get a sense of absolute control. BUT I have a niggling suspicion that i.t.o. musicality the DX is at the forefront.
After the Krell clones- I am finished with big audio projects. From then on it's low cost minimalist projects only.
My thinking now is also to build a 4 channel version that I can use for experimental work.
Nordic
Please explore the PSU board option. The neater the better.
I have a DIY Nelson Pass "Bride of Zen" pre-amp which I suspect will work very well with the DX as it is also a very simple one stage design.
Jozua
To increase your power you will need some small modifications
There's a resistance to feed the zenner.... it is 2K2... and this one will need increase if you double the supply voltage, you must double this resistance...so...there's a ratio... easy to calculate.
Using 55 volts, a good idea is to place, at least, 3 pairs in the output...better to go to 4 pairs if you will use 4 ohms loads.
All your transistors will need a check up if they can hold the rail to rail voltage.... plus 55 volts and minus 55 volts can produce 100 volts of swing (some losses into transistors)...so... every transistor must be checked for that.
The current we have into the VAS is already enougth...do not need to change the bootstrapp resistances.... they are fine.
You will have more power, even in the stand by mode, because the increase of voltage...so...even the VAS transistors will need heatsink.... also you can use two BD139 as VAS
Each output transistor will need it's own emitter resistances, and those one can be 0.47 ohms if you will use 4 output pair, 0.22 ohms if you will use 3 output pairs.
Each output transistor will need Its own base resistance... 2,2 ohms to 4.7 ohms will be fine.
Your fuses will need to be re-calculated
And all your condenser will need increasing in insulation voltages.
The off set will work fine, also the bias adjustment.
The difference is that you may check the current you have into output units...at least 5 miliamps to each transistor....measure over the emitter resistances.
Good luck!
regards,
Carlos
There's a resistance to feed the zenner.... it is 2K2... and this one will need increase if you double the supply voltage, you must double this resistance...so...there's a ratio... easy to calculate.
Using 55 volts, a good idea is to place, at least, 3 pairs in the output...better to go to 4 pairs if you will use 4 ohms loads.
All your transistors will need a check up if they can hold the rail to rail voltage.... plus 55 volts and minus 55 volts can produce 100 volts of swing (some losses into transistors)...so... every transistor must be checked for that.
The current we have into the VAS is already enougth...do not need to change the bootstrapp resistances.... they are fine.
You will have more power, even in the stand by mode, because the increase of voltage...so...even the VAS transistors will need heatsink.... also you can use two BD139 as VAS
Each output transistor will need it's own emitter resistances, and those one can be 0.47 ohms if you will use 4 output pair, 0.22 ohms if you will use 3 output pairs.
Each output transistor will need Its own base resistance... 2,2 ohms to 4.7 ohms will be fine.
Your fuses will need to be re-calculated
And all your condenser will need increasing in insulation voltages.
The off set will work fine, also the bias adjustment.
The difference is that you may check the current you have into output units...at least 5 miliamps to each transistor....measure over the emitter resistances.
Good luck!
regards,
Carlos
Turn-on
Guys, I really look forward to building and listening to this amp!
After full-range testing I plan to use it in an active speaker setup,
where it shall drive a tweeter directly without a DC-blocking cap.
Do you think, turn-on clicks or pops could be an issue?
Somewhere down the thread I read that output DC should be quite low, so this one should be okay, right?
Would you recommend a turn-on protection with a relay?
Thanks for your help!
----------
konkret
Guys, I really look forward to building and listening to this amp!
After full-range testing I plan to use it in an active speaker setup,
where it shall drive a tweeter directly without a DC-blocking cap.
Do you think, turn-on clicks or pops could be an issue?
Somewhere down the thread I read that output DC should be quite low, so this one should be okay, right?
Would you recommend a turn-on protection with a relay?
Thanks for your help!
----------
konkret
Bob, although your parts list will certainly work, I have a few changes mostly related to the power rail capacitors... buy 8 of those 3300uf caps and use them all around, I however use 4700u + 10000u on my boards, also the zeners for the VBE will vary on your rail voltages...
I have rather low rails at 35V and use 2 16V zeners in series, in stead of the 33V ones you listed, those will be fine for slightly higher supplies, also your part numbers matches Greg's schematic, and differs from mine, so thismay give builders a little hard time figureing out what goes where when they get their boards.
Feel free to get the components but wait for the official BOM before you get carried away, all resistors and small caps look right on your BOM, as well as transistors (once again some part numbering differs)
I don't feel it right for me to just copy Greg's work, therefore there will be some slight diffirences between our work, I am busy building the website that goes with the boards.
Thank you for your enthusiasm.
There is no turn on click with my unit and it plays long until draining the caps at which point it just softly fades away and it sounds like it exhales softly, nothing nasty.
Of coarse if you use large toroidals you will need to take the measures needed for softstart etc. just as for anything you would build for them... but this is not due to the amp part.
Yes, as long as your input transistors and their resistors are reasonably well mathced, the amp will take care of offset automaticaly.
I have rather low rails at 35V and use 2 16V zeners in series, in stead of the 33V ones you listed, those will be fine for slightly higher supplies, also your part numbers matches Greg's schematic, and differs from mine, so thismay give builders a little hard time figureing out what goes where when they get their boards.
Feel free to get the components but wait for the official BOM before you get carried away, all resistors and small caps look right on your BOM, as well as transistors (once again some part numbering differs)
I don't feel it right for me to just copy Greg's work, therefore there will be some slight diffirences between our work, I am busy building the website that goes with the boards.
Thank you for your enthusiasm.
There is no turn on click with my unit and it plays long until draining the caps at which point it just softly fades away and it sounds like it exhales softly, nothing nasty.
Of coarse if you use large toroidals you will need to take the measures needed for softstart etc. just as for anything you would build for them... but this is not due to the amp part.
Yes, as long as your input transistors and their resistors are reasonably well mathced, the amp will take care of offset automaticaly.
Hi guys sorry the Wiki is not up yet... been trying to get one up, but it seems I'm getting old.. will look at the instructions again today.
Sam, the maximum size you can "make fit" is 30mm on the front ones (I did), requires removal of spades... I don't see how you can go bigger than that... design is for 18 to 25mm type.
You could probably mount them offboard with little wires... like I did in the original DX.. Or keep em for the PSU...
Sam, the maximum size you can "make fit" is 30mm on the front ones (I did), requires removal of spades... I don't see how you can go bigger than that... design is for 18 to 25mm type.
You could probably mount them offboard with little wires... like I did in the original DX.. Or keep em for the PSU...
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