Thank you @seventenths! It's toner transfer. I still have a few sheets of inkjet photo paper stashed away and replaced that laser printer 10 years ago but it never made it to the recycling as I can't seem to let it go in case I ever do another pcb ...
16 years later ... it doesn't get as much play time as it used to but it's still part of the lineup. The heatsinks are on the small size but I found that even at 1.0A bias, the harmonic profile of the F5 doesn't change (ratio of H2/H3 ...), it probably just doesn't stay in class A as long but at least it's avoided being retired.
I rebuilt it a few years ago into this case and updated the PSU but bumped it down to 1.0A to keep the heat under control.
I rebuilt it a few years ago into this case and updated the PSU but bumped it down to 1.0A to keep the heat under control.
I've had perfectly usable results in the past with little effort but a couple of recent trials have been sub-standard. . I'm tempted to try actual iron-on-transfer paper but will make another effort or two first, including the Archival Print function (higher temp) but that may be a step in the wrong direction. No harm in trying.
Cheers
Hello,
I took a short break because I got sick.
I will probably recover by the weekend.
Thank you very much to everyone who helped during this time.
I liked it a long time ago from this forum. I printed it on A4 paper using toner transfer and ironing method. Then I have to thank you for this beautiful pcb.
note: p3 is already mounted on the card.
Hi guys!
I hope you can give me a sanity check
It's an F5, for headphones (planars like Susvara, so gain is pretty much the same) with ALFET lateral MOSFETs from the givaway.
I adjusted some things:
1. Lowered bias resistors R105/106 and trimmers to 1k to be more in the range of ALFETs cutoff voltage. They start between 0,5V - 1,5V I gave some headroom, this should give me a nice play around 2,5V
2. Lowered the current protection to trigger around 2,6A. Still way too much, might go even further by lowering the R115/116 to 1Ohm to be around 1,3A. Still kinda much though.
3. I want bias around 150mA giving me a clean 1W @ 64Ohms with a huge margin. And MOSFETs like to be run hot.
My questions are as follows:
1. Is this a right direction?
2. Did I forgot about something and it will blow up in my face?
3. How to handle gain switch? Relay connecting additional resistance across R109/110/111/112, thus lowering the gain?
Thanks!
I hope you can give me a sanity check
It's an F5, for headphones (planars like Susvara, so gain is pretty much the same) with ALFET lateral MOSFETs from the givaway.
I adjusted some things:
1. Lowered bias resistors R105/106 and trimmers to 1k to be more in the range of ALFETs cutoff voltage. They start between 0,5V - 1,5V I gave some headroom, this should give me a nice play around 2,5V
2. Lowered the current protection to trigger around 2,6A. Still way too much, might go even further by lowering the R115/116 to 1Ohm to be around 1,3A. Still kinda much though.
3. I want bias around 150mA giving me a clean 1W @ 64Ohms with a huge margin. And MOSFETs like to be run hot.
My questions are as follows:
1. Is this a right direction?
2. Did I forgot about something and it will blow up in my face?
3. How to handle gain switch? Relay connecting additional resistance across R109/110/111/112, thus lowering the gain?
Thanks!
Attachments
Short edit: to get 150mA of bias I would need around 0,7V of Vgs, so I guess we can make the resistances even lower.
I have matched quad of 2SK163/2J44 (IDSS : 7.x mA).
If I want to use that jfets to F5 which resistor values should I adjust? (I don't have much of knowledge on electronics)
And If there's some general rule is it applicable to F5m, F7, F4, M2X?
Byongho
Thanks.
My advise ?
Sell your quad to someone who knows how to use them properly.
Get yourself a kit at the DIYStore, like e.g. the F5m.
If you have problems, there are plenty of people at the thread to help.
Cheers,
Patrick
Patrick,
Thank you for quick reply.
It seems that it's not as simple as I think.
I will study the LT-SPICE simulation tool for the future project.
Byongho
Thank you for quick reply.
It seems that it's not as simple as I think.
I will study the LT-SPICE simulation tool for the future project.
Byongho
So a buddy of mine had this F5 kit from apparently a long time ago, I think it's a V2, but does anyone recognize this board set? I'm going to try to assemble it using the V2 schema. Anyone have knowledge of this version of board / kit?
I think that’s an @Peter Daniel board. It says audio sector on the power supply board.
I’m assuming you have another channel.
I’m assuming you have another channel.
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I do, yes, actually I have 3 more amp boards and another power supply board. I'm gonna try to put together a shopping list tomorrow and try to build these. I did check that website, but it doesn't seem like it's a product they offer anymore. The friend that left them with me also sent an e-mail to someone that he got them from.
I'm glad someone recognized them, though. Makes me feel better about building it, lol
Check this out:
ORIGINAL GROUP BUY
Man, it's good to see someone else has a board hoarding drawer...I don't even have boards of that vintage!
ORIGINAL GROUP BUY
Man, it's good to see someone else has a board hoarding drawer...I don't even have boards of that vintage!
You mean like perhaps the first build guide I did…?
https://www.diyaudio.com/community/threads/an-illustrated-guide-to-building-an-f5.188691/
That's a beauty all right! My favorite is the hole tapping photo...it's only missing the sound effect:
DSCF3584.jpg
3003.mp3
DSCF3584.jpg
3003.mp3
Anyone seriously interested in building the F5(T) with original MOSFETs (NNNN-PPPP matched) can drop me a PM.
EU preferred, due to postage costs and customs declaration.
Patrick
EU preferred, due to postage costs and customs declaration.
Patrick
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Thanks guys, I think I'm on the right track now. The parts that were with this amp included the toshiba fets for the outputs Q3 and Q4 (2sk1530/2sj201) and the inputs, (2sj74/2sc170) but not Q5 and Q6, ZTX450 and ZTX550 are specified, but are obsolete on Digikey.
Is there a good alternative that people have been using lately?
Is there a good alternative that people have been using lately?