I found this project :
http://users.otenet.gr/~athsam/HAFLER_DH_200.htm
Wonder if the following can be used in replacement of the original
IRFP240+IRFP9240 2SK134+2SJ49
2N5416, 2N3439 2N5415, 2N3440
2N5551 2N5550
Tks
http://users.otenet.gr/~athsam/HAFLER_DH_200.htm
Wonder if the following can be used in replacement of the original
IRFP240+IRFP9240 2SK134+2SJ49
2N5416, 2N3439 2N5415, 2N3440
2N5551 2N5550
Tks
I found this project :
http://users.otenet.gr/~athsam/HAFLER_DH_200.htm
Wonder if the following can be used in replacement of the original
IRFP240+IRFP9240 ----- 2SK134+2SJ49
2N5416, 2N3439 ----- 2N5415, 2N3440
2N5551 ----- 2N5550
Tks
http://users.otenet.gr/~athsam/HAFLER_DH_200.htm
Wonder if the following can be used in replacement of the original
IRFP240+IRFP9240 ----- 2SK134+2SJ49
2N5416, 2N3439 ----- 2N5415, 2N3440
2N5551 ----- 2N5550
Tks
There is a difference between vertical and lateral MOSFETs.
The DH-200 and later Hafler amps used lateral MOSFETs from Hitachi. These MOSFETs were developed primarily for audio, not switching, applications. These MOSFETs are still available from Profusion (UK) under the brand name of Exicon, and are drop in replacements for original Hitachi devices. Heck, I even have a few Hitachi MOSFETs I can sell you.
Why try to re-engineer an amp when all its parts are still available?
http://www.profusionplc.com/hitachi.htm
Why don't you re-engineer the Hafler XL-280's differential input section to use FETs that are more available and maybe even use dual devices that contain matched pairs. There are XL-280 amps languishing because replacement FETs used in the input section are not easily available or their few sources charge a lot of $$$ for them. Just a thought.
You can find the schematic you referenced here, complete with the entire original user's assembly manual:
http://hafler.com/techsupport/pdf/DH-200_amp_man.pdf
Dick
The DH-200 and later Hafler amps used lateral MOSFETs from Hitachi. These MOSFETs were developed primarily for audio, not switching, applications. These MOSFETs are still available from Profusion (UK) under the brand name of Exicon, and are drop in replacements for original Hitachi devices. Heck, I even have a few Hitachi MOSFETs I can sell you.
Why try to re-engineer an amp when all its parts are still available?
http://www.profusionplc.com/hitachi.htm
Why don't you re-engineer the Hafler XL-280's differential input section to use FETs that are more available and maybe even use dual devices that contain matched pairs. There are XL-280 amps languishing because replacement FETs used in the input section are not easily available or their few sources charge a lot of $$$ for them. Just a thought.
You can find the schematic you referenced here, complete with the entire original user's assembly manual:
http://hafler.com/techsupport/pdf/DH-200_amp_man.pdf
Dick
xl-280 jfet inputs
Dick,
You can surely find other FETs for the input but the problem is to get the proper characteristics. For the same jfet part number the variation in IDss and Vp parameters is so wide that you need to select the proper IDss and also match the devices otherwise it could not even work at all! You can also try at some extent to replace the jfet source resistors and the resistor between the source resistors with potentiometers but even then a minimum of matching would be required. Thus, the main problem is the availability of the proper IDss and matched devices. Borbely www.borbelyaudio.com site sells matched devices if you are ready to pay the price! I suppose that Erno Borbely would be able to even suggest a fine replacement for the input jfets.
One other problem is the pin out (G-D-S) of the jfet that varies from one part number to the other (where bjt casing defines most of the time the B-C-E pin out).
Dick West said:There is a difference between vertical and lateral MOSFETs.
...Why don't you re-engineer the Hafler XL-280's differential input section to use FETs that are more available and maybe even use dual devices that contain matched pairs. There are XL-280 amps languishing because replacement FETs used in the input section are not easily available or their few sources charge a lot of $$$ for them. Just a thought.
...df[/url]
Dick
Dick,
You can surely find other FETs for the input but the problem is to get the proper characteristics. For the same jfet part number the variation in IDss and Vp parameters is so wide that you need to select the proper IDss and also match the devices otherwise it could not even work at all! You can also try at some extent to replace the jfet source resistors and the resistor between the source resistors with potentiometers but even then a minimum of matching would be required. Thus, the main problem is the availability of the proper IDss and matched devices. Borbely www.borbelyaudio.com site sells matched devices if you are ready to pay the price! I suppose that Erno Borbely would be able to even suggest a fine replacement for the input jfets.
One other problem is the pin out (G-D-S) of the jfet that varies from one part number to the other (where bjt casing defines most of the time the B-C-E pin out).
Safe_Cracker,
The "big deal" about these kit amps from the early 80s is that they were a very good product and very well priced -- at that time. All their parts are still available and the original manuals, schematics and parts lists are still available. Hence, a lot of us have used them almost exclusively since the early 80s. Plus many have found the sound of the original DH-200 can be easily improved by replacements of certain passive parts.
Does your estate sale amp work? I will give you $10 for it which represents a 100% profit on your investment.
The "big deal" about these kit amps from the early 80s is that they were a very good product and very well priced -- at that time. All their parts are still available and the original manuals, schematics and parts lists are still available. Hence, a lot of us have used them almost exclusively since the early 80s. Plus many have found the sound of the original DH-200 can be easily improved by replacements of certain passive parts.
Does your estate sale amp work? I will give you $10 for it which represents a 100% profit on your investment.
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