Actually, MarianB's design is fine and still common as the basis of many others here. Samuel is right pointing out a VAS improvement but the output stage transistors are really a bigger problem for overall linearity.
It's O/T but I've tried to get TIP33-36 to sound good a few times and had to give up because there are now several much better audio parts commonly available for about the same money; 2SC5200/A1493 for example, will make quite an audible difference. You can then use the BD139/40 probably better as drivers and something faster for the VAS pair - as already discussed.
The topology is capable of quite good hi-fi and you certainly don't need deep pockets for hi-fi amplifiers, just appropriate choices and now those parts don't cost much more than bog-standard power transistors. I imagine that is the case in Romania too.
It's O/T but I've tried to get TIP33-36 to sound good a few times and had to give up because there are now several much better audio parts commonly available for about the same money; 2SC5200/A1493 for example, will make quite an audible difference. You can then use the BD139/40 probably better as drivers and something faster for the VAS pair - as already discussed.
The topology is capable of quite good hi-fi and you certainly don't need deep pockets for hi-fi amplifiers, just appropriate choices and now those parts don't cost much more than bog-standard power transistors. I imagine that is the case in Romania too.
Basic Lin topology like this one rely heavily on good quality components ,
it s just that its simplicity make it far more sensitive to initial conditions ,
read linearity of the components.
Just look at the THD ratios of such early designs and their siblings
using fast components in the mid/late 70s in japânese amps.
it s just that its simplicity make it far more sensitive to initial conditions ,
read linearity of the components.
Just look at the THD ratios of such early designs and their siblings
using fast components in the mid/late 70s in japânese amps.
Think "now" as 30 years ago.
A designer here used TIP35/36 in his first power amp model development, kept blowing the output devices, untill he could get his hands on Japanese ring-emitters.
That was the early 1980s, told me the story face to face a couple of years later.
Not meaning to belittle MarianB, but such a 5-minute design is either an exercise or building something with stuff from the parts bin.
Pragmatic is plucking such a copy & paste design from the web.
(either one, a single pair TIP35/TIP36 output stage on 40V rails isn't smart)
All of you shouldn't be so quick to pass judgement on something without actually knowing nothing about it, it did not posted that desighn here to debate it ( Now i regret doing so ), nor did i even explained it, not even in big details, you have no ideea why i desighned something like that and still you do not hesitate to accuse me of plagiarism, of copying someone else, and i'm reffering here to @jacco vermeulen who i assure i've copyed nowone, all the calculations needed, all the circuits are done by me, granted i too like many others have got my general inspiration on books, but as they say, books are writen from other books and some personal imput. Everyone has theyr knowlege especially from books and maybe some personal experiments for those that actually afford the expense of fancy equipment, so i cannot be accused by something that most do on regular bases-taking my ideeas, my knowlege from books, as far as i know, nowone has reinvented the wheel.
So even thow i would have wanted to set something straight so you would know why i desighned it, and you would have understud that it was needed but now i'm not so sure it is a good ideea, like anywhere else there are still people that like to pass wrong judgement quiqly without knowing the facts, i do not presume to wonder why, i just state the fact as it is.
Good day to all of you so called experts
So even thow i would have wanted to set something straight so you would know why i desighned it, and you would have understud that it was needed but now i'm not so sure it is a good ideea, like anywhere else there are still people that like to pass wrong judgement quiqly without knowing the facts, i do not presume to wonder why, i just state the fact as it is.
Good day to all of you so called experts
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You should read a TIP35/36 datasheet.
I've got loads and loads of such parts, only good for building regulated power supplies and flea amps.
Total cost of building a power amp does not justify using such devices, totally unpragmatic, regardless what it is intended for.
An A1943/C5200 pair does as little as $5 or less, even if the TIP35/36 were free of charge, they're not worth the saving.
Same story for the Vas devices, unless you have Philips BD139/140 by the pound as me.
The design is 101 grade, from the input cap to the standard Zobel, nothing to do with accusations.
"without actually knowing nothing about it" means one actually does know a thing or two.
I've got loads and loads of such parts, only good for building regulated power supplies and flea amps.
Total cost of building a power amp does not justify using such devices, totally unpragmatic, regardless what it is intended for.
An A1943/C5200 pair does as little as $5 or less, even if the TIP35/36 were free of charge, they're not worth the saving.
Same story for the Vas devices, unless you have Philips BD139/140 by the pound as me.
The design is 101 grade, from the input cap to the standard Zobel, nothing to do with accusations.
"without actually knowing nothing about it" means one actually does know a thing or two.
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I repeat, you know nothing so please avoid making assumptions or passing judgment, i do not have the time nor the will to debate with you on this topik, not when your that biased, i would only waste both of our time so i would ask a MOD please delete all my postings on this topik, or at least my pic with my desighn.
Of course, you are right about the time scale, jacco. TBH I don't know what availability and local buying prices of components has been in eastern Europe but I think financial constraints slow the acceptance of technology advances more than the availability of high quality components and new ideas that go with them, so I opt to give the benefit of the doubt with design choices, whatever I may expect of other members' DIY standards.
BTW, I didn't buy TIPs for amplifiers, I used the little Sankens at the time.
I think I have a good hint for people looking for BF871 BF872 replacement. Fairchild has some nice transistors, with an ft of about 150MHz, much like the BF-types from Philips. It is the KSC3503 and KSA1381. They come in different Hfe flavors, check the data sheet here.
Navelpluis says cheerio to you all ;-)
Navelpluis says cheerio to you all ;-)
Hi,
2SC3902/A1507 in TO126 package, 2SC3649/A1419 in TO243 package and 2SC4027/A1552 in TO251 package are available from ON semi, since ON semiconductors acquired Sanyo semiconductors. the above mentioned color TV audio drivers would serve excellent VAS devices. Check their datasheets, they have impressive specs.
Also, i have used Fairchild MJE340/350 for VAS in my designs, to me they serve good and are very robust devices and are easily available. they show < 0.005% THD20 performance at VAS positions, in simulation atleast.
Regards,
Aniket
2SC3902/A1507 in TO126 package, 2SC3649/A1419 in TO243 package and 2SC4027/A1552 in TO251 package are available from ON semi, since ON semiconductors acquired Sanyo semiconductors. the above mentioned color TV audio drivers would serve excellent VAS devices. Check their datasheets, they have impressive specs.
Also, i have used Fairchild MJE340/350 for VAS in my designs, to me they serve good and are very robust devices and are easily available. they show < 0.005% THD20 performance at VAS positions, in simulation atleast.
Regards,
Aniket
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Those devices definitely have good specs, and they are mentioned in many discussions on the DIY Audio Forums. The problem is that the KSC3503 seems to available only in the "D" grade (nominal Hfe of 100) while the KSA1381 is only available in the "E" grade (nominal Hfe of 150) - hence, they are not very well matched as complements. In an emitter follower that's probably of no consequence, but becomes problematical in a voltage gain stage aiming for lowest distortion.
Dale
Yes, they are readily available in complementary grades. The data sheet specs look decent. The collector capacitance isn't as good as the KSC3503/KSA1381 but the current ratings are higher so they are more attractive as line- or output stage-drivers.
A quick scan of the Data Sheets suggests that these may be the same die chips in different packages. That suggests they may be good choices for a published DIY project that will have both a thru-hole and an SMT version, without significant differences in measured performance. However, some of the devices don't seem to be readily available to hobbyists and other mere mortals who don't order parts by the reel. The collector capacitance is just a little better than KSA1220A/KSC2690A, even though the Ft isn't as good.
dale
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