30VAC
I've personally tested the P3A with 2SA1943/2SC5200 on 42VDC rails and I don't recommend it. MJL4302 is more suitable.
50% level means that at 50+50 volts the P3A is expected to produce about 120W at 8R load and 50% means that you play with about 50-60w power on real speakers of 8R constantly all day and leave the rest of the 60W for dynamic peaks to spread easily...
Drive the amp in 120W for a period of 15-20 minutes no matter how good is your heatsink and you will loose it pretty quickly ...
As about 1943 5200 here we have plenty of options starting from 0.75 euro a piece obviously very fake , we also have variations in the region of 1.5, 2, 2.5 and so on but i always used Toshiba that cost almost 5 euro each to be on the safe side .
Extensive tests also in quite high rail voltage proved that Fairchild clones of 1943 5200 are far more rugged than the Toshiba and stand a lot more abuse before blow ....Point is that for some reason these doesn't sound the same good as the Toshiba Don ask me why ... I don't have an idea
Kind regards
Sakis
Drive the amp in 120W for a period of 15-20 minutes no matter how good is your heatsink and you will loose it pretty quickly ...
As about 1943 5200 here we have plenty of options starting from 0.75 euro a piece obviously very fake , we also have variations in the region of 1.5, 2, 2.5 and so on but i always used Toshiba that cost almost 5 euro each to be on the safe side .
Extensive tests also in quite high rail voltage proved that Fairchild clones of 1943 5200 are far more rugged than the Toshiba and stand a lot more abuse before blow ....Point is that for some reason these doesn't sound the same good as the Toshiba Don ask me why ... I don't have an idea
Kind regards
Sakis
There is no reason to use those expensive, high voltage versions of On-Semi parts when your rail voltages are only ~40V. Use the cheapest available T0264 types (MJL3281/1302) which are under $5 US in 1-off qty. from Mouser or Digi-key. The difference between MJL0281,3281,4281 etc and their complements is only in their Vceo,cbo. - just like the difference between TIP31A,B,C or TIP41A,B,C etc.
There is no secret sauce in HV transistors that leads to audio Nirvana. They are specifically designed for current sharing in big, high rail voltage arrays of perhaps 8-20 pairs in PA amps or such. In Rod's comments, I recall him saying he had to keep changing the On-semi types to avoid fakes and poor results reflecting badly on his design. If you are using genuine parts from authorized suppliers, there is no need to play this cat-and-mouse game with the fake suppliers that make life difficult for many of ESP's customers who live in countries where private foreign purchases are extremely difficult and local sources just sell whatever comes cheap.
There is no secret sauce in HV transistors that leads to audio Nirvana. They are specifically designed for current sharing in big, high rail voltage arrays of perhaps 8-20 pairs in PA amps or such. In Rod's comments, I recall him saying he had to keep changing the On-semi types to avoid fakes and poor results reflecting badly on his design. If you are using genuine parts from authorized suppliers, there is no need to play this cat-and-mouse game with the fake suppliers that make life difficult for many of ESP's customers who live in countries where private foreign purchases are extremely difficult and local sources just sell whatever comes cheap.
No why ...as said are pretty rugged but sound kinda harsh I could say more suitable to rock heavy metal sounds and so on if you are into juzzy things vocals and strings go for Toshiba
BD139 well don't use them any more but you may go with Philips usually grey color are fine but buy a few measure them see how it works cause there is plenty of variations out there ..ST is also fine may as well ON SEMI
Though as said MJE150xx series are in the hard rock family where ever you put those the sound is harder and metallic avoid them ( not only in the P3A in general repairs used the result was the same especially if those where replacing Japanese types )
My favorites is BD 829-830 dirt cheap expect them easy to find and sound the best to my ears extremely warm sound ...If stamped made in Hong kong trust them are fine ...get also a few see hfe readings , observe stamping, target is to get transistors of the same type family batch and era if matched between them will play better.
Kind regards
sakis
BD139 well don't use them any more but you may go with Philips usually grey color are fine but buy a few measure them see how it works cause there is plenty of variations out there ..ST is also fine may as well ON SEMI
Though as said MJE150xx series are in the hard rock family where ever you put those the sound is harder and metallic avoid them ( not only in the P3A in general repairs used the result was the same especially if those where replacing Japanese types )
My favorites is BD 829-830 dirt cheap expect them easy to find and sound the best to my ears extremely warm sound ...If stamped made in Hong kong trust them are fine ...get also a few see hfe readings , observe stamping, target is to get transistors of the same type family batch and era if matched between them will play better.
Kind regards
sakis
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You only need to avoid fake products by buying from authorized sellers/agents - not Ebay or other online traders with only their website/marketing organization membership to say who they are but no mention of their sources.
Actually, cloned products are not necessarily bad but it is annoying to see deceptive offers like:
"Quantity 100 ea. Toshiba 2SC1815 ---- $5.00."
But what you get is:
Quantity 100 ea. Wing Shing 2SC1815 ----$5.00
I have received product from European suppliers under these pretences too. A certain German Ebay seller offered Sanken transistors as Japan source but eventually they arrived as Chinese Inchange Semi parts - nothing like any Japanese, exclusively Sanken branded LAPT power transistor,
It comes down to your supplier's integrity
Thank you.
Dear Mr Sakis and all of you,
I just want to say thanks to you all for this help and advice given so far, I really appreciate it and I think this is a fantastic and friendly thread.
I'm expecting my boards any day now and thanks to you I'm busy compiling my components list for ordering.
Any words of advice regarding the caps?
Kind Regards
Roy.
Dear Mr Sakis and all of you,
I just want to say thanks to you all for this help and advice given so far, I really appreciate it and I think this is a fantastic and friendly thread.
I'm expecting my boards any day now and thanks to you I'm busy compiling my components list for ordering.
Any words of advice regarding the caps?
Kind Regards
Roy.
caution in miller caps ., two of them one in the VAs stage Q4 and one in the lower driver Q6 my choice there is silver mica 500V rated and in no case what you put there can be ceramic of 63V .
Input capacitor will make a difference value of 4.7 u is more than plenty choose a component that is rated as low voltage possible and as less physical size ...after that any you try will play some role but difference will be hardly traceable still though existing .
my choice is wima MKS2.2uf rated at 63 V pitch 5mm and i use two of them back to back parallel to my ears sounded the best and cheap to my pocket ...
Finally input filter C2 220pf i use styroflex but expect this to add nothing to the quality of sound ( i got them available and also the use of styroflex in filters is short of a fetich )
Kind regards
Sakis
Input capacitor will make a difference value of 4.7 u is more than plenty choose a component that is rated as low voltage possible and as less physical size ...after that any you try will play some role but difference will be hardly traceable still though existing .
my choice is wima MKS2.2uf rated at 63 V pitch 5mm and i use two of them back to back parallel to my ears sounded the best and cheap to my pocket ...
Finally input filter C2 220pf i use styroflex but expect this to add nothing to the quality of sound ( i got them available and also the use of styroflex in filters is short of a fetich )
Kind regards
Sakis
Member
Joined 2009
Paid Member
call me 'cloth ears' but I've found multilayer np0 ceramic caps to work very nicely, they are not the same thing as the cheap ceramics used for power rail decoupling at all. I have used Silver Mica too, but never compared them side by side wiyh ceramic in the same amp. In my latest amp (upgraded P3a) I use ceramic and it sounds very good. Of course I don't have the same experience as Sakis and the Silver Mica might be best. If you have time and energy to compare, please let me know what you find.
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Testing was done it is also mentioned in some of my posts in the past where a P3A board was made with ""anything available ) parts no matched transistors carbon resistors and what ever capacitors
This was done in order to evaluate the role of the quality of parts in an amplifier construction .
Further more the initial board had classic ceramic capacitors for miller caps rated at 63 V which is something that has to do with safety ( miller caps should be rated in as higher voltage possible since often these have to face rail to rail voltage and some other nasty things ) .
The result was pretty bad amplifier measured and sounded far far worst than a properly made one .
Going from classic brownish capacitors to the blue ones improved by far both measuring and sound but still the leader is mica caps .
In between a test was made with yellowish multilayer ceramics that actually sounded pretty fine while the voltage ratings was still an issue .
From a repair aspect in many amplifiers we repair and in some cases compensation is to be altered or upgraded use of mica also proved to be an upgrade and have been verified by costumers through the years .
From stability aspects you can actually get away with a few PF less in critical points like the Vas that will set the amp even more free as long as you use a good quality part such a mica 2% . ( and you are able to verify that )
The only test that hasn't been done was the use of styroflex as miller caps since those have been used by a few manufacturers in this application but since i have seen them failing there in Rotel equipment i decided not to use the or put them in extensive tests since the sound of them is really superb .
I like the amps i make to last 100 domestic years so yeap styroflex can only be used as input filter .
Kind regards
Sakis
This was done in order to evaluate the role of the quality of parts in an amplifier construction .
Further more the initial board had classic ceramic capacitors for miller caps rated at 63 V which is something that has to do with safety ( miller caps should be rated in as higher voltage possible since often these have to face rail to rail voltage and some other nasty things ) .
The result was pretty bad amplifier measured and sounded far far worst than a properly made one .
Going from classic brownish capacitors to the blue ones improved by far both measuring and sound but still the leader is mica caps .
In between a test was made with yellowish multilayer ceramics that actually sounded pretty fine while the voltage ratings was still an issue .
From a repair aspect in many amplifiers we repair and in some cases compensation is to be altered or upgraded use of mica also proved to be an upgrade and have been verified by costumers through the years .
From stability aspects you can actually get away with a few PF less in critical points like the Vas that will set the amp even more free as long as you use a good quality part such a mica 2% . ( and you are able to verify that )
The only test that hasn't been done was the use of styroflex as miller caps since those have been used by a few manufacturers in this application but since i have seen them failing there in Rotel equipment i decided not to use the or put them in extensive tests since the sound of them is really superb .
I like the amps i make to last 100 domestic years so yeap styroflex can only be used as input filter .
Kind regards
Sakis
Well, your own local sellers of silicon antiquities, Dalbani, sell them on Ebay UK and if you like paying even more, Little Diode will get them for you.
BD829 BD830 Transistor TO 202 Pair | eBay