First a big thankyou to you for posting your build and also do. to all the peop that keeps diyaudio.com running.
If you have not bought your Beyerdynamic yet you should listen to the 990 before going for the 880.
I actually prefer the 990 overall than the 880 for casual listening (and I am not alone)+(I also have 3 Stax phones to give you an indication of the quality level I am going out from)
http://www.4sound.dk/shop/hovedtelefoner/beyerdynamic/dt-990-pro-250-ohm.html
And its more than 800 Danish Dollars cheaper than the 880 (approx 135 USD)
You can listen to it at Aage (4sound) store but bring your own music and equipment, cause aages is not the best.
If you are looking for a phone for Ipad/Iphone give the DT1380 ad listen too.
http://www.4sound.dk/shop/hovedtelefoner/beyerdynamic/dt-1350.html
Even if it is 80 Ohm it gives a good sound level cause of its high efficiency.
Maybe that comes from the powerfull magnets used ?
My son prefers the DT1350 to the 990 for use in his recording/mixing sessions, also why you can wear them for ours w/o problems, so if you are young and not like me only can hear max 14-15 kHz tops that can (may) be the phone for you.
Yes i notished that phone also, have to listen to it and bringing the 990 (250 ohm)with me so I can compare them, also trying to persuade Aage to take The Tesla T1 home so I could hear it.
But until now w/o luck.
Talking about headband, for me the 990 and the Stax SR-202 fits my head much better than the SR-507 so a fit test on top of the listening test is mandatory for me.
Btw have you considered to offer paired transistors together with the PCB cause hate to buy maybe 100pcs to get only the few needed for the Thor ?
Well, I do have some input JFET's left(bought 50 each of SK246/SJ103) but they aren't that closely matched, I could maybe match each pair within 1mA IDSS and each N and P channel pair within 1mA IDSS. Matching within 1mA IDSS should be more than close enough. But it is time consuming and I'm a little lazy
Would probably have to charge $20 USD for a complete set of matched JFET's for 2 Thor Amp Boards, not exactly cheap. Ebay is cheaper.
I also have more than enough of KSC3503 and KSA1381 BJT transistors left and they require no matching.
I don't have any 2SK1056/2SJ162 Lateral FET's left.
Well, I do have some input JFET's left(bought 50 each of SK246/SJ103) but they aren't that closely matched, I could maybe match each pair within 1mA IDSS and each N and P channel pair within 1mA IDSS. Matching within 1mA IDSS should be more than close enough. But it is time consuming and I'm a little lazy
Would probably have to charge $20 USD for a complete set of matched JFET's for 2 Thor Amp Boards, not exactly cheap. Ebay is cheaper.
I also have more than enough of KSC3503 and KSA1381 BJT transistors left and they require no matching.
I don't have any 2SK1056/2SJ162 Lateral FET's left.
I will try to pm you so we can talk
I have ordered MKII of my amp board PCB's and they are on their way to me. I have also ordered MKII of my No Thump PCB's, they should be shipped sometime this week or earlier next week.
I'm almost ready to buy a pair of Beyerdynamic DT 880 PRO 250 Ohm headphones, maybe I'll have them next weekend for testing on V1 of my amp. Should give a good idea of the performance on MKII, since the designs are almost 100% identical and with the same performance.
So besides upgrading all my boards to MKII I'm also changing the volume pot in my amp. I had a little bit of background noise(NOT 50 or 100 Hz from mains) when turning my 50K pot above 10 O'clock, going down to 10K would hopefully reduce that. Also, you still get all kinds of crappy sounds from your PC when connecting the amp directly to the PC. Getting a decent USB DAC(Cambridge Audio DacMagic 100 most likely) should also improve the noise levels.
I'm almost ready to buy a pair of Beyerdynamic DT 880 PRO 250 Ohm headphones, maybe I'll have them next weekend for testing on V1 of my amp. Should give a good idea of the performance on MKII, since the designs are almost 100% identical and with the same performance.
So besides upgrading all my boards to MKII I'm also changing the volume pot in my amp. I had a little bit of background noise(NOT 50 or 100 Hz from mains) when turning my 50K pot above 10 O'clock, going down to 10K would hopefully reduce that. Also, you still get all kinds of crappy sounds from your PC when connecting the amp directly to the PC. Getting a decent USB DAC(Cambridge Audio DacMagic 100 most likely) should also improve the noise levels.
This thread has been quiet for a while but expect to see a few updates this month.
I have been preparing for my exams the last 7 weeks so I haven't had much time for this project. However, this Wednesday I passed my exams with top marks, which means that I am now an Electronics Technician, Yay for me.
Anyway, since I now have Amp Board MKII and No Thump Board MKII PCB's in my hands I can move along with mounting and testing of those PCB's. I don't expect any issues since the MKII PCB's are basically the same designs with a few tweaks and fixes as well as small layout changes.
I expect to be finished with those 2 MKII boards before the end of this month with the Supply Board MKII finished sometime next month.
I have been preparing for my exams the last 7 weeks so I haven't had much time for this project. However, this Wednesday I passed my exams with top marks, which means that I am now an Electronics Technician, Yay for me.
Anyway, since I now have Amp Board MKII and No Thump Board MKII PCB's in my hands I can move along with mounting and testing of those PCB's. I don't expect any issues since the MKII PCB's are basically the same designs with a few tweaks and fixes as well as small layout changes.
I expect to be finished with those 2 MKII boards before the end of this month with the Supply Board MKII finished sometime next month.
This thread has been quiet for a while but expect to see a few updates this month.
I have been preparing for my exams the last 7 weeks so I haven't had much time for this project. However, this Wednesday I passed my exams with top marks, which means that I am now an Electronics Technician, Yay for me.
Anyway, since I now have Amp Board MKII and No Thump Board MKII PCB's in my hands I can move along with mounting and testing of those PCB's. I don't expect any issues since the MKII PCB's are basically the same designs with a few tweaks and fixes as well as small layout changes.
I expect to be finished with those 2 MKII boards before the end of this month with the Supply Board MKII finished sometime next month.
I have finally upgraded my Thor headamp with MKII Amplifier Boards and MKII No Thump Boards.
Increased supply rails to +/-15VDC, reduced bias to around 120 mA pr output FET.
My amp is now significantly cooler running than before, mostly because I'm using the same transformer as before so I only have to drop a few volts across the regulators instead of around 5 volts with +/-12 VDC supplies. Total quiescent current of the amp is also reduced from 200mA to 160mA and that also helps with the heat.
The sound? No difference at all compared to V1 which is what I expected.
Only things left somewhere in the future when I get around to it, is an upgrade of my Supply Board to MKII and substituting the 50K Alps RK27 volume pot with a 10K version of the same.
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What do you mean? I haven't raised the bias and no, there is no issue with raising the bias, it will just run hotter thats all. But remember to have enough cooling.
I mean that I want to do it
Since the output FET's are 7A/100W devices you could easily crank the bias up to 500-1000mA pr FET, however, doing so would require significantly more cooling than the SK129 heastsinks I'm using on my board.
But with enough cooling, no problem.
Also it puts pressure on the supply board, I really wouldn't have each supply board rail deliver more than 500-800 mA continously, which basically means that with 1 supply board you should not have each amp board using more than 250-400mA in total. However, you could go dual mono or make your own supply board to overcome those issues.
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This project is done.
Been an interesting experience, had a few issues that luckily got resolved and I learned a few things along the way.
In total Thor has been up and running for around 2.5 months without any issues and it has seen almost daily use.
Only got one thing left to do, making MKII of my supply boards. That will be done sometime next month, need to make a small change, adding a few more ground terminals for my high voltage, high impedance driving headamp Mjølner.
Which means that I will be able to use the same supply board for both headamps.
Been an interesting experience, had a few issues that luckily got resolved and I learned a few things along the way.
In total Thor has been up and running for around 2.5 months without any issues and it has seen almost daily use.
Only got one thing left to do, making MKII of my supply boards. That will be done sometime next month, need to make a small change, adding a few more ground terminals for my high voltage, high impedance driving headamp Mjølner.
Which means that I will be able to use the same supply board for both headamps.
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English :
I only sell PCB's so unless you know how to source the right components as well as matching the input JFET's and adjusting bias I would not recommend building it.
I'll happily sell people the bare PCB's but nothing else than that.
I only design stuff for myself and to satisfy my own curiosity.
Danish :
Jeg sælger kun PCB'er, så medmindre du selv vil finde og købe de rigtige komponenter, matche input JFET's og justere bias så vil jeg ikke anbefale at bygge det.
Jeg vil med glæde sælge PCB'er men ikke andet end det.
Jeg designer kun for mig selv og for at tilfredstille min egen nysgerrighed.
Been listening to Thor driving my brand new 250 Ohm Beyderdynamic DT 880 PRO headphones.
They are slightly too bright for my usual taste but nothing I cant get used to since the rest of the sound spectrum is almost perfect.
The way this headphone delivers details is insane, I'm hearing completely new details in music that I have been listening to for years.
First a good DIY headphone amp that took my setup to completely new levels and now a pair of high'endish headphones delivers even more sound quality. Now a good audiophile soundcard like Asus Xonar STX should complete the picture.
They are slightly too bright for my usual taste but nothing I cant get used to since the rest of the sound spectrum is almost perfect.
The way this headphone delivers details is insane, I'm hearing completely new details in music that I have been listening to for years.
First a good DIY headphone amp that took my setup to completely new levels and now a pair of high'endish headphones delivers even more sound quality. Now a good audiophile soundcard like Asus Xonar STX should complete the picture.
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