i actually did .... in many stress tests it looks like a very good quality device ...seems though that it has specs on its own and diferent from toshibas ( against the law i try to mix toshibas and faichild which ofcourse didnt work ) still the sound next to the original 2SA 1302 3281 combo is not5 that good
kind regards sakis
kind regards sakis
Then you simply don't have a P3a anymore.
Don't be surprised also that the combination with CFP output stage adds up to something awful.
I've built a couple of such simple amplifiers with MJ15003/4 transistors and that's how most people
judged the sound with standard low bias.
With high bias, like 300mA, most amplifiers sound good but not often as specially good sounding for the money as a well built P3a
thanks wahab for the input and the PM .. let's not mix up here is a discussion of a different story ...
Ian is right .... few of the builders keep the P3a in low bias most of them is working above 70ma .. still the bootstrap will be more musical than the CCS ...one may choose from that ..
As about the P3A i have no intention to change the basis ... will play around though ....
happy new year !!
Ian is right .... few of the builders keep the P3a in low bias most of them is working above 70ma .. still the bootstrap will be more musical than the CCS ...one may choose from that ..
As about the P3A i have no intention to change the basis ... will play around though ....
happy new year !!
all right then ....
its been bugging me for some time to play with a couple of things ... one to try a P3A modified for higher input impedance... aim was something like 100K but finally i started with 47K
Target was to make he amp more friendly to a preamplifier which i am very happy with the DOZ i am listening the past one year but if dynamics are better with the 47K at low levels i might as well go back to a passive thingy .
Then since the specific amp will work for my bench the load is Z=8 R and that will be a fact that will not change and also the actual required power will be less than 20W for every day casual listening i though about boosting the rails to 50+50 volts to gain room for dynamic peaks ...
first listening impressions are more or less spectacular sound is more analytic bass is very tight ( middle got a bit better than previous setups ) high is plenty and crisp while everything is crystal clear ....
with bias of 70 ma for starts all seem to be fine i might as well stay there but next week i am going to see what happens with higher ...
Other than that all the rest is pretty much standard ...here is a description of the setup
----2*35 volt trafo rated at 1kva
---120.000 mfd of total capacitance
---220mfd +2.2 mks decoupling on board
---MJE 150xx Vas with 100pf miller
---my favorite drivers Bd 829-830
--- Drivers on a common heat sink with the VBE attached to it
---closely matched LTP with thermal junction
---and of course legendary original 2SA1302 2SC 3281 pair for the output
enjoy some foto and i am willing to post also measured scope readings after playing with bias and miller caps
kind regards and a very happy new P3A to everyone..... oooops i mend new year !!!
its been bugging me for some time to play with a couple of things ... one to try a P3A modified for higher input impedance... aim was something like 100K but finally i started with 47K
Target was to make he amp more friendly to a preamplifier which i am very happy with the DOZ i am listening the past one year but if dynamics are better with the 47K at low levels i might as well go back to a passive thingy .
Then since the specific amp will work for my bench the load is Z=8 R and that will be a fact that will not change and also the actual required power will be less than 20W for every day casual listening i though about boosting the rails to 50+50 volts to gain room for dynamic peaks ...
first listening impressions are more or less spectacular sound is more analytic bass is very tight ( middle got a bit better than previous setups ) high is plenty and crisp while everything is crystal clear ....
with bias of 70 ma for starts all seem to be fine i might as well stay there but next week i am going to see what happens with higher ...
Other than that all the rest is pretty much standard ...here is a description of the setup
----2*35 volt trafo rated at 1kva
---120.000 mfd of total capacitance
---220mfd +2.2 mks decoupling on board
---MJE 150xx Vas with 100pf miller
---my favorite drivers Bd 829-830
--- Drivers on a common heat sink with the VBE attached to it
---closely matched LTP with thermal junction
---and of course legendary original 2SA1302 2SC 3281 pair for the output
enjoy some foto and i am willing to post also measured scope readings after playing with bias and miller caps
kind regards and a very happy new P3A to everyone..... oooops i mend new year !!!
oki doki
the wild P3a is up and running
as i said the sound is more or less the same like the old P3A only even more tight more analytic and there also a major improvement in the middle area
at 120ma amplifier runs very cool and one thing that made a very obvious difference was that in the old setup leaving class A was obvious and sound changed a lot i class AB ...( i am currently listening in low level power and with near field monitors so details like that are very obvious )
the specific set up seems that doesn't get that bad when leaving class A ...
enjoy my vbe multiplier and some pics of under construction
the wild P3a is up and running
as i said the sound is more or less the same like the old P3A only even more tight more analytic and there also a major improvement in the middle area
at 120ma amplifier runs very cool and one thing that made a very obvious difference was that in the old setup leaving class A was obvious and sound changed a lot i class AB ...( i am currently listening in low level power and with near field monitors so details like that are very obvious )
the specific set up seems that doesn't get that bad when leaving class A ...
enjoy my vbe multiplier and some pics of under construction
Hi Wahab,
Could you please show how to do this?
I would like to try using your ccs scheme
forum is about talking about opinions and ideas ..so here is mine about one subject
just listened for the first time an Aleph ... Point is that i consider my shelf as a very experienced listener ... I listen to most of he amplifiers i repair and come to think about it ia have been listening almost everything that is made with transistors
Procedure is to use always the same music always the same speakers may also use the same preamp generally the same set up so you go from step A to step B
For starts that was aleph 3 i think its very properly made and here is how it sounded to my ears
----power wise obviously there is no point of any comparison the P3A is by far more powerful ( even though that was never the question )
----The aleph has by far less lower end both in size and also in depth ... the remaining bass is clean, tight, not especially rich , not especially upfront but generally clean informative and clear
----As about the middle which was supposed to be the ultimate weapon of the Aleph actually is very clean quite transparent But obviously one step behind and with reduced stage presentation and information ( big surprise there )
--- Finally high was one of the best i have ever listen to, plenty informative ,crystal clear but seemed that this amount of high doesn't actually fit to the rest of the picture . Also generally even though high was more than plenty a small sense of compression or boost but only frequency wise ( frequency wise TRY TO EXPLAIN : think like you have a 32 band eq where everything ios flat except +5 db in 16KHZ and the will give the impression that the rest of the band is slightly compressed next to 16 khz ) .....seemed that this type of high was a part of another amplifier "added" to the aleph
the general impression left to me was that i am listening to a B1 buffer simply amplified a few times
thanks for listening
kind regards
sakis
just listened for the first time an Aleph ... Point is that i consider my shelf as a very experienced listener ... I listen to most of he amplifiers i repair and come to think about it ia have been listening almost everything that is made with transistors
Procedure is to use always the same music always the same speakers may also use the same preamp generally the same set up so you go from step A to step B
For starts that was aleph 3 i think its very properly made and here is how it sounded to my ears
----power wise obviously there is no point of any comparison the P3A is by far more powerful ( even though that was never the question )
----The aleph has by far less lower end both in size and also in depth ... the remaining bass is clean, tight, not especially rich , not especially upfront but generally clean informative and clear
----As about the middle which was supposed to be the ultimate weapon of the Aleph actually is very clean quite transparent But obviously one step behind and with reduced stage presentation and information ( big surprise there )
--- Finally high was one of the best i have ever listen to, plenty informative ,crystal clear but seemed that this amount of high doesn't actually fit to the rest of the picture . Also generally even though high was more than plenty a small sense of compression or boost but only frequency wise ( frequency wise TRY TO EXPLAIN : think like you have a 32 band eq where everything ios flat except +5 db in 16KHZ and the will give the impression that the rest of the band is slightly compressed next to 16 khz ) .....seemed that this type of high was a part of another amplifier "added" to the aleph
the general impression left to me was that i am listening to a B1 buffer simply amplified a few times
thanks for listening
kind regards
sakis
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In general I agree with Sakis' assessment of the Aleph3. But ime many things can change the sound when it is a DIY. I believe Sakis' amp is the commercial one (with matched output mosfets)?
In general it is hard to get the bass to an audiophile standard, but I experienced having special pairs that gave incredible bass performance. The mosfets were not even in the same class with the original Aleph.
In general it is hard to get the bass to an audiophile standard, but I experienced having special pairs that gave incredible bass performance. The mosfets were not even in the same class with the original Aleph.
Hey Sakis, just want you to know how much I enjoy your 'war stories' about the various amps you repair. I learn heaps by seeing how you fix and often improve on what lands on your workbench. Keep up the great work....I hope there are some more posts coming.
And how is the wild P3a coming along? Still keeping you happy and warm
And how is the wild P3a coming along? Still keeping you happy and warm
Hey Sakis, just want you to know how much I enjoy your 'war stories' about the various amps you repair. I learn heaps by seeing how you fix and often improve on what lands on your workbench. Keep up the great work....I hope there are some more posts coming.
And how is the wild P3a coming along? Still keeping you happy and warm
ha ha ha ...yeap P3A remains my favorite .. as we speak i produce a new pcb design every now and then and also try various combination of semis in search for the best possible .... I have fun though in between
just an update ...the wild version 50 volt rails and 47K input configuration offered nothing extreme after all may be a kick more as said in the middle and also proved some bias issues still it was just a bit better than the original if driven by a passive pot
Small marginal improvement was the use of BC 549 C i found with hfe of almost 600 .... but the rails are back to 40V at the max
Kind regards
sakis
That's the price for simplicity of a single ended design. It should be included in the design objectives (no trial and error). Lazy Cat's SSA is simple also, but it is not "straight forward" either.
I will be building an amp intended to beat the P3A. It is a fair contest because of the same parts, same number of stages. I copied the operating points of each transistors in the P3A. The simulation is clearly far more superior, don't know with the actual result. I think it will still like comparing apple to orange because unlike the P3A I used EF output (I think more people wil opt for EF in a blind test anyway).