Tayda thumbs down!
Thats very cheap attitude on Tayda's part. I will skip on purchases of active devices from them. thanks for info.
Thats very cheap attitude on Tayda's part. I will skip on purchases of active devices from them. thanks for info.
Hi,
Ok,It was the name given to the Amp by Juan AX-14TP (whose Layout I have used ).
No comments on the other things wrt my last post ??
Now coming to the recent events, I finally bought the 1K multiturn pot and some other things.
Now one by one as the events unfolded.
1) I changed the 1K and replaced it with 2.2K as suggested earlier along with the 1K multiturn pot, I was able to set the bias now and started with 15mv(45ma) and went up till 45mv (137ma). The heatsink now started to show its true colours ! With 45mv it was getting too much for those puny heatsink and they almost ready to give up,So had to turn it back to 15mv.
2) One channel functioned without a hitch but the other channel gave me nightmares and 2 sleepless nights (literally with me breaking my head all through the day and going on till 4Am of the next morning), I checked and rechecked but to no avail,The positive half would not swing and I got Negative DC at the output. None of the output device and associated devices on the heatsink had failed or such. I have applied the yellow tape (thermal one which Terry uses,its called copper tape here locally) and on top of it have the good old mica too for additional safety,So there is no chance of outputs touching the heatsink,Also I currently have not grounded the heatsink.
I removed the whole set of transistors with the heatsink and put in the working channel to check but there to it gave the same results making me suspect either my meter has developed a fault ( as I check each and every transistor on the heatsink thrice or more number of times) or the devices although showing proper reading in the meter has developed god knows what issue !
After 2days I had given up and had just decided to junk the whole transistor set and replace it with the new one's,But before that I just wanted to try one more trick to see if that yielded any results. So I just removed one pair and try to run only one pair of output,Viola it sang !! Now why in the world it did that I have no idea,I now soldered the second pair and to my astonishment it worked too,Now the whole dead channel was working ! Am posting this cause,One I want to know why it did what it did and two to give people an answer if they ever encounter such problems.
3) I as suggested and as intended earlier thermal coupled all the small signal devices (A970 with BC547,547 with 557),Also got the 547 and 557 from the same make (Philips),Will 340 and 350 put on a same heatsink help ??
With the above I was able to bring down the DC Offset to -2 to -3mv.
Now that all the troubleshooting and tweaking was over,I sat and listened. with the 45mv setting the only thing I noticed was elevated bass levels,The robust bass just was terrific (although it was short lived as had to tone it down due to heatsink going crazy),but other then that nothing much changed.
With bias 15mv the sound seemed more or less the same albeit less bass (not totally absent or anything but less as compared to the other setting).
Went up gradually from there till 30mv to check the sound,at 30mv although sound was same but heatsink was running hot (not way too much to cause device failure but still much for them to hold for long duration listening). Also one more thing that I noticed was that even though I set it to 30ma the sound was still missing something,even devices were running bit hot the sound was not all that I can say exciting which I kinda did when it was cold and with zero bias (with 1K ),So I just reverted back to the 1k and now no more heat to worry and sound is almost to my liking,If someone care to explain why is this ?? Asking cause I have read in many places that devices running hot or little more bias will make it perform better (not in the exact terms I know,take it with a pinch of salt) or sound good,But it was hardly the case,so curious to know why.
I had so many things to write here but Am totally lost,Anyways Finally I just wanted to post the findings.
Regards.
Ok,It was the name given to the Amp by Juan AX-14TP (whose Layout I have used ).
No comments on the other things wrt my last post ??
Now coming to the recent events, I finally bought the 1K multiturn pot and some other things.
Now one by one as the events unfolded.
1) I changed the 1K and replaced it with 2.2K as suggested earlier along with the 1K multiturn pot, I was able to set the bias now and started with 15mv(45ma) and went up till 45mv (137ma). The heatsink now started to show its true colours ! With 45mv it was getting too much for those puny heatsink and they almost ready to give up,So had to turn it back to 15mv.
2) One channel functioned without a hitch but the other channel gave me nightmares and 2 sleepless nights (literally with me breaking my head all through the day and going on till 4Am of the next morning), I checked and rechecked but to no avail,The positive half would not swing and I got Negative DC at the output. None of the output device and associated devices on the heatsink had failed or such. I have applied the yellow tape (thermal one which Terry uses,its called copper tape here locally) and on top of it have the good old mica too for additional safety,So there is no chance of outputs touching the heatsink,Also I currently have not grounded the heatsink.
I removed the whole set of transistors with the heatsink and put in the working channel to check but there to it gave the same results making me suspect either my meter has developed a fault ( as I check each and every transistor on the heatsink thrice or more number of times) or the devices although showing proper reading in the meter has developed god knows what issue !
After 2days I had given up and had just decided to junk the whole transistor set and replace it with the new one's,But before that I just wanted to try one more trick to see if that yielded any results. So I just removed one pair and try to run only one pair of output,Viola it sang !! Now why in the world it did that I have no idea,I now soldered the second pair and to my astonishment it worked too,Now the whole dead channel was working ! Am posting this cause,One I want to know why it did what it did and two to give people an answer if they ever encounter such problems.
3) I as suggested and as intended earlier thermal coupled all the small signal devices (A970 with BC547,547 with 557),Also got the 547 and 557 from the same make (Philips),Will 340 and 350 put on a same heatsink help ??
With the above I was able to bring down the DC Offset to -2 to -3mv.
Now that all the troubleshooting and tweaking was over,I sat and listened. with the 45mv setting the only thing I noticed was elevated bass levels,The robust bass just was terrific (although it was short lived as had to tone it down due to heatsink going crazy),but other then that nothing much changed.
With bias 15mv the sound seemed more or less the same albeit less bass (not totally absent or anything but less as compared to the other setting).
Went up gradually from there till 30mv to check the sound,at 30mv although sound was same but heatsink was running hot (not way too much to cause device failure but still much for them to hold for long duration listening). Also one more thing that I noticed was that even though I set it to 30ma the sound was still missing something,even devices were running bit hot the sound was not all that I can say exciting which I kinda did when it was cold and with zero bias (with 1K ),So I just reverted back to the 1k and now no more heat to worry and sound is almost to my liking,If someone care to explain why is this ?? Asking cause I have read in many places that devices running hot or little more bias will make it perform better (not in the exact terms I know,take it with a pinch of salt) or sound good,But it was hardly the case,so curious to know why.
I had so many things to write here but Am totally lost,Anyways Finally I just wanted to post the findings.
Regards.
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I buy from Tayda often. I have probably bought and installed 50 pair of 2SK1058/2sj162 from them and never had an issue. I have received other parts that were faulty but they were always good about issuing a credit once they verified there was a problem. The Renasas devices are good or I wouldn't have suggested them. I is OK if you chose not to believe me. I am only trying to help.
Blessings, Terry
Blessings, Terry
Hi Terry,
That many numbers of laterals might be sufficient for a life long stock for me.
prasi
Hi Terry,
That many numbers of laterals might be sufficient for a life long stock for me.
prasi
I have built several amps that use them. Slewmaster mini, VSSA, Peeceebee, TuBuSuMo just to name a few. Now these cool little amps Mile has designed. I like them a lot for their power handling ability, thermal stability and sound. Great devices in my book.
How about connecting the NFB to ''dirty'' GND as it is and just lifting the inGND pin with 10R resistor. I am lifting GND this way in my CFA amps, I do not know if it is correct or not but amp works and measures fine.
Regards Peter
they sure are in my book too (last three out of four amps I built have laterals)....thats why people prefer them for music reproduction.... I want to try Nico Ras amplifier someday.
reg
prasi
I believe you if you say they're the real deal. Like I stated before, I was referring to op-amps being counterfeit.
The only transistors I purchased from Tayda that were counterfeit were some BC550 or 560 "B" grades. They were supposed to be Fairchilds, but it was obvious the "F" and numbering on them looked suspicious.
Five dollars each isn't a bad price on the latfets from Tayda. Plus their shipping charge is very reasonable.
I purchased mine from Jack at Tech-DIY:
Tech DIY Company Store
FX9 pcb PDF files with recommended correction from Mr. Miles.
Attachments
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OK, I found the "correction". The NFB ground is connected directly to power ground. SGND is still lifted. I tried it both ways and I don't see or hear any difference. The FX9 has crisper square waves in the upper frequencies but is a little less stable in offset. Not enough to affect the sound at all. You can see the servo working all the time. Tomorrow I will hook both the FX8 and FX9 to my A/B setup and see if there is any audible difference.