Yep...now i have all the informations...so..not needed anymore to use AC128
this way may sound better.
Now i have all part numbers...thank you Jacco Vermeulen
regards,
Carlos
................................................................................
Fótios..it is all right... you have the rigth to publish or not...relax and be happy..receive the hug i am sending and let it be.
regards,
Carlos
this way may sound better.
Now i have all part numbers...thank you Jacco Vermeulen
regards,
Carlos
................................................................................
Fótios..it is all right... you have the rigth to publish or not...relax and be happy..receive the hug i am sending and let it be.
regards,
Carlos
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Thanks Jacco for explanation for Carlos...Only one little notice: BF469-472 are out of program, but they can be replaced by other similar ( video ) types...
These stated amps was designed in the year 96, so they are relatively old. Past good experiences with them ( mosfet ones ), next step was design of little bit more powerful model, called TYA I ( Ten Years After
Pavel,
I have no idea how your amplifier sounds, but the construction is nothing short of ART! Incredible quality throughout in the design and construction. Bravo!
Self-applause stink, you know, Spirtos..and I do not like descriptions of sound by words, because it can be very tendentious. Some people like sound of tubes, some bipolars, some mosfets... Sound of amp is result of many aspects, as you certainly know. I do not say, that my amps are the best, maybe your is better, I do not know.... But if you show me your schematic and results of measuring, I will tell you, how it will be sound ( of course with limits by words ), believe me or not...
Personally I prefer mosfet amps with error correction and think that Mr.Popa one is the best, what I saw to this time, again believe or not...
And do not think, that I am looking only to " eyes " or design, my demands to sound are very high...
Best regards to Athens,
Pavel
Personally I prefer mosfet amps with error correction and think that Mr.Popa one is the best, what I saw to this time, again believe or not...
And do not think, that I am looking only to " eyes " or design, my demands to sound are very high...
Best regards to Athens,
Pavel
I strongly believe that your realisations sound good Pavel. Besides I have studied a little your schematics like DPA386 (I have good experience with these fets). I only state a personal desire
. I have no attitude to dispute your design philosophy and knowledge I am sorry if there was any misconception.Imo there are good results with any component (tubes, fets, bipolar) however I prefer mostly fets and sometimes tubes
Indeed, a good engineer, with strong background and experience can understand a lot from schematics and measurements.
My honest regards to Praque too, I should travel there someday.
Spiros
This question is pointed to those who have designed something:
- How many times have you experienced failure when it comes to sound reproduction?
- How many times have you experienced top score when it comes to sound reproduction?
Answer q 2: Very often
Pavel,
After you had the finished schematic how long did it take to assemble these nice amplifiers. Just acquiring all of the parts would take a few months.
Are those boards etched or machine routed? To have a set of boards with those dimensions produced at a fab house would be quite expensive.
I hope you do not stay away so long next time. We diy types get a great deal of inspiration from seeing what our projects could turn out like if we get at it.
Thanks Tad
After you had the finished schematic how long did it take to assemble these nice amplifiers. Just acquiring all of the parts would take a few months.
Are those boards etched or machine routed? To have a set of boards with those dimensions produced at a fab house would be quite expensive.
I hope you do not stay away so long next time. We diy types get a great deal of inspiration from seeing what our projects could turn out like if we get at it.
Thanks Tad
It's funny, how many people have noticed "peasant" cable ties (on electrolytics) on this splendid "regal" design.
Looking at pic. in post 40, I see the transistors leads are bent very cose to their cases.
I hope that was done according to the manufacturer specifications/requirements (stress/integrity issue). Do you see any benefit in routing and soldering them under the board?
Altogether, it is very impressive design.
Looking at pic. in post 40, I see the transistors leads are bent very cose to their cases.
I hope that was done according to the manufacturer specifications/requirements (stress/integrity issue). Do you see any benefit in routing and soldering them under the board?
Altogether, it is very impressive design.
Based on my own experience, one suggestion for a future project/layout:
Extending the PCB over the heatsink mounted devices as shown in this post http://www.diyaudio.com/forums/showthread.php?p=1940001 is not the best practice. Due to the high dissipation in the power devices, the PCB (in particular if it has a ground plane) will get pretty hot and, sooner or later, all kind of very hard to debug issues may occur (starting with drying out electrolytics, in particular 85 degs types, and ending with soldering cracks because of the high thermal stress). As much as possible, the PCB should stay off from the top of the power devices like here http://www.diyaudio.com/forums/showthread.php?p=1883792 or, even better, here: http://www.diyaudio.com/forums/showthread.php?p=1866841 , this may provide (according to my measurements) 5-10 degs less at the board level , which could make a significant difference in time.
Extending the PCB over the heatsink mounted devices as shown in this post http://www.diyaudio.com/forums/showthread.php?p=1940001 is not the best practice. Due to the high dissipation in the power devices, the PCB (in particular if it has a ground plane) will get pretty hot and, sooner or later, all kind of very hard to debug issues may occur (starting with drying out electrolytics, in particular 85 degs types, and ending with soldering cracks because of the high thermal stress). As much as possible, the PCB should stay off from the top of the power devices like here http://www.diyaudio.com/forums/showthread.php?p=1883792 or, even better, here: http://www.diyaudio.com/forums/showthread.php?p=1866841 , this may provide (according to my measurements) 5-10 degs less at the board level , which could make a significant difference in time.
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You are right if the amp would do heavy duty service but at home I think this is a rather good solution and since I have worked with industrial power electronics I don't fear high temperatures any more. 60-70 deg C is nothing
and this is regarded as really hot if you are an amateur.syn08, I think your complaints are based on theory and not real life. Electronics feel better if they run cool but how good is the lifetime for Pavel's amps? Pretty good I think.
Scuse me for bugging in, but Pavels use of stand-0ff blocks for the power devices enables him to mount the boards at a larger distance to the heatsinks.
Airflow between PCB and heatsink should ample protect the components against overheating, especially if the chimney has such a width.
Looks see for yourself : http://www.diyaudio.com/forums/attachment.php?attachmentid=142569&d=1254426778
Airflow between PCB and heatsink should ample protect the components against overheating, especially if the chimney has such a width.
Looks see for yourself : http://www.diyaudio.com/forums/attachment.php?attachmentid=142569&d=1254426778
I don't fear high temperatures any more. 60-70 deg C is nothing
syn08, I think your complaints are based on theory and not real life. Electronics feel better if they run cool but how good is the lifetime for Pavel's amps? Pretty good I think.
Jeezzz... guys, you are so sensitive to any suggestion
You make me believe there's a little more at stake here than a simple DIY project Assuming a 60-70 deg C in the proximity of the case of the power devices is totally unrealistic. I have measured these temperatures, and your assumption means that the heatsink itself would stay at max. 50-60 deg. C.
A class AB amp of 100W/8ohm would have a maximum dissipation (worst case, at 64% output swing) of about 82W. This is really a theoretical value, because it does not take into consideration the supply voltage overhead and the bias power (and you like it hot, isn't it
) In the real life this is never under, say, 100W.Now, assume the best plastic case power devices; they have a Rth of 0.54 deg/W Also assuming the heatsink has 0.5 deg/W (optimistic, what's in the pictures looks more like 0.8 deg/W) and 0.5 deg/W for the mounting (again optimistic) gives a total Rth between the junction and the HS of 1.54 deg/W./ Now, assume you are using 2 pairs of power devices (common for 100W) a quick calculation gives the HS at 50 deg over ambient, the device case at 62.5 over ambient and the device junction at 75 deg over ambient. Take the ambient temperature as 25 deg and do the math. The HS is at 75 deg, the case is at 82.5 deg and the board will be at minimum 75 deg.
This is for only 100W/8ohm, without even considering real load impedances! I'll let other decide if this is acceptable for them, I would personally not even think about running a la longue 85 deg electrolytics at 75 degs, without any margin (in particular about the ambient temperature value). In this particular case, I would either consider a 10% safety margin or, as I am currently doing, provide temperature triggered forced cooling. I set my sensors at 85 degrees for the HS temperature and a microcontroller is taking care of the rest.
If anybody is interested, I can upload a YouTube movie about my latest microcontroller supervisor (power supply, temperature, offset, overload), built around an Atmega1280 chip. Will be public and free (hardware schematics and software source code) when it's up running in the YAP 2.1 amp, by the year end.
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