Two channels ba1 working
Yesterday evening finished the second channel powerstage of ba 1.
A very little hum (in spite of more than 369.000uf in the powersupply).
1000va transformers
input signals are taken from gridpin of second tubesocket of Beard p100mkII.
One thing is for sure this is a complete different sounding amp than the Beard p100 that I have been used to for the last years.
I wil keep comparison reports for later.
The amount off subjective available power (3x 0.6 Amp) does certainly not disapoint! Especially not after everything I read here about needed power.
But it needs more for my old b w 801 s with only 86 db sensitivity
As it is hardwired I left space to put two extra mosfets in.
In two more weeks or so i will finish another two channels and make this a balanced amp. Which will give me 8x0.6amps
AND HERE IS A QUESTION since heatsinks are probably larger than in the original it is not running very hot. So can someone advise me whats the best and simpel way to raise bias a little.
And what will be the maximum current per device and by which it´s lifespan won´t be significantly shorted. (providing I stick to the 5 seconds putting hand on heatsink test)
All in all adding mosfets, making it balanced, raising bias, and later on doubling the efficiency as Nelson spoke about
will make this also for my low sensitivity speaks a VERY NICE amp.
Yesterday evening finished the second channel powerstage of ba 1.
A very little hum (in spite of more than 369.000uf in the powersupply).
1000va transformers
input signals are taken from gridpin of second tubesocket of Beard p100mkII.
One thing is for sure this is a complete different sounding amp than the Beard p100 that I have been used to for the last years.
I wil keep comparison reports for later.
The amount off subjective available power (3x 0.6 Amp) does certainly not disapoint! Especially not after everything I read here about needed power.
But it needs more for my old b w 801 s with only 86 db sensitivity
As it is hardwired I left space to put two extra mosfets in.
In two more weeks or so i will finish another two channels and make this a balanced amp. Which will give me 8x0.6amps
AND HERE IS A QUESTION since heatsinks are probably larger than in the original it is not running very hot. So can someone advise me whats the best and simpel way to raise bias a little.
And what will be the maximum current per device and by which it´s lifespan won´t be significantly shorted. (providing I stick to the 5 seconds putting hand on heatsink test)
All in all adding mosfets, making it balanced, raising bias, and later on doubling the efficiency as Nelson spoke about
will make this also for my low sensitivity speaks a VERY NICE amp.http://www.diyaudio.com/forums/pass-labs/142055-burning-amplifier-ba-1-a-28.html#post3324219
So my heatsinks are to small, i knew i was playing with fire using 6 pairs! Still 65 c even with lower bias. ZM, putting the amp on end did help to cool it, but I am going back to the drawing board. I have an under biased f5 c. That will go in this chassis.
Alettagla, you can parallel another source resistor, maybe 10R.
So my heatsinks are to small, i knew i was playing with fire using 6 pairs! Still 65 c even with lower bias. ZM, putting the amp on end did help to cool it, but I am going back to the drawing board. I have an under biased f5 c. That will go in this chassis.
Alettagla, you can parallel another source resistor, maybe 10R.
Thank you coils was hoping for another solution since it took me quit some trouble matching al the source resistors.
When I know what is the maximum bias per mosfet withoud shortening its lifespan to much just changing source resistors should even for me be a simple calculation.
Anyway in your case why not lower bias even more Im right now lisstening with a total of 1,8 amp bias and its stil playing very nice. Allthough it´s running out off breath with more serious listening levels but when you have about 6db more sensitive speaks al might be well.
And then when Nelson tells us the secret of how efficiency can be doubled ..... All mightbe fine
At least you have heard some single ended class A
When I know what is the maximum bias per mosfet withoud shortening its lifespan to much just changing source resistors should even for me be a simple calculation.
Anyway in your case why not lower bias even more Im right now lisstening with a total of 1,8 amp bias and its stil playing very nice. Allthough it´s running out off breath with more serious listening levels but when you have about 6db more sensitive speaks al might be well.
And then when Nelson tells us the secret of how efficiency can be doubled ..... All mightbe fine
At least you have heard some single ended class A
I hope that you had some proper clearance between heatsink bottom end and surface
say that 50mm is sufficient ; fact that you're not seeing that on commercial amps is simple - who would ship and sell amps with 50mm tall legs
two of your heatsinks would normally be used for a standard F5 stereo amp
or might do a balanced stereo
but you have 2 channels of BA-1 on one heatsink
I suspect to make a balanced stereo amp
well, two heatsinks ought to work for a stereo amp, or one balanced mono amp
btw, if yours is a copy of Nelson original layout with 6 pairs, I suppose it was still meant to be mounted on two heatsink
meaning, a normal stereo chassis with two heatsinks would do one mono amp
but not very convenient for balanced, which I guess is one reason for the 3-pair option
ZM, I agree on the clearance.
two of your heatsinks would normally be used for a standard F5 stereo amp
but you have 2 channels of BA-1 on one heatsink
I suspect to make a balanced stereo amp
well, two heatsinks ought to work for a stereo amp, or one balanced mono amp
This amp is not balanced, just 6 pairs deep, I'm the irrational one spoken of elsewhere. This chassis is now home to an f5 c. The BA is getting a bigger chassis. *
two of your heatsinks would normally be used for a standard F5 stereo amp
but you have 2 channels of BA-1 on one heatsink
I suspect to make a balanced stereo amp
well, two heatsinks ought to work for a stereo amp, or one balanced mono amp
This amp is not balanced, just 6 pairs deep, I'm the irrational one spoken of elsewhere. This chassis is now home to an f5 c. The BA is getting a bigger chassis. *
adding an aleph current source
Here´s a question,
I have two powerstages/bufferstages of ba 1 working. Two are being soldered together to make it a balanced version. Even then I´m affraid I won´t have enough power.
Well then I have been reading the zen 2 paper and here is my (novice) question.
Could I add pair of resistors,a cap and in this way add an Aleph current source. (details have to be worked out)
What are pro´s and con´s of using Cheff de Gaars UGS module as frontend.
(I have boards and 2sj109BL in the drawer)And how wil it compared to bba3
(by the way wouldn´t a set up with the aleph current source and UGS module bring me close to the more commercial passlabs models...?)
Your advice is most welcom
Here´s a question,
I have two powerstages/bufferstages of ba 1 working. Two are being soldered together to make it a balanced version. Even then I´m affraid I won´t have enough power.
Well then I have been reading the zen 2 paper and here is my (novice) question.
Could I add pair of resistors,a cap and in this way add an Aleph current source. (details have to be worked out)
What are pro´s and con´s of using Cheff de Gaars UGS module as frontend.
(I have boards and 2sj109BL in the drawer)And how wil it compared to bba3
(by the way wouldn´t a set up with the aleph current source and UGS module bring me close to the more commercial passlabs models...?)
Your advice is most welcom
making my BA/1 more efficient
Hmm I have been patiently waiting for a response to the above question but since were no replies I started experimenting.
I tried to add an Aleph current source as it is implemented and explained in one of the ZEN papers.
(or at least what I understood from it)
That means from the output with a capacitor and resistor back to the base of the ztx450 biasing transistor. This resulted in a very unpleasant screaming occilation which, despite of several attemts I couldn´t stop.
Never mind we learn best from our mistakes. But right now Im stuck.
Nelson Pass explained to us in the beginning of this thread that in a later version he would explain to us a (novelty) way of how to double the efficiency of the BA1
Could someone please explain why adding an aleph current source doesn´t work or what I might have done wrong?
Or could perhaps Nelson himself already reveal how to double the efficiency of this amp?
Any ideas are most welcom
Hmm I have been patiently waiting for a response to the above question but since were no replies I started experimenting.
I tried to add an Aleph current source as it is implemented and explained in one of the ZEN papers.
(or at least what I understood from it)
That means from the output with a capacitor and resistor back to the base of the ztx450 biasing transistor. This resulted in a very unpleasant screaming occilation which, despite of several attemts I couldn´t stop.
Never mind we learn best from our mistakes. But right now Im stuck.
Nelson Pass explained to us in the beginning of this thread that in a later version he would explain to us a (novelty) way of how to double the efficiency of the BA1
Could someone please explain why adding an aleph current source doesn´t work or what I might have done wrong?
Or could perhaps Nelson himself already reveal how to double the efficiency of this amp?
Any ideas are most welcom
well - that's sometimes happening - ppl are either not seeing someone's question , or they just don't have enough time to invest , to reply properly
in this moment I don't have enough headtime - to find BA-1 sch , blast it on secondary display and read what you asked
maybe tomorrow , if nobody else jump in
in this moment I don't have enough headtime - to find BA-1 sch , blast it on secondary display and read what you asked
maybe tomorrow , if nobody else jump in
Can you post a schematic of your modification and some photos of the boards.
Running the FE balanced and addint to output bias will give you more power. Increasing bias, improves linearity and gives more current for low ohm loads. In order to get more more power into higher ohmic load, you need to increase rail voltage or use balanced FE. This turns output stage into a bridged topology, effectively doubling the current into the double the load....assuming you have the current to support that load. In other words, an amp capable of 50W into 4 ohms will do 100W into 8 ohms, as balanced/bridged amp. BA3B FE has BIG potential.
Hi Buzzforb,
Thanks for your help.
I know that increasing bias will give more power and this will indeed become a balanced version. I also think that together with BBA3 and doubbling the efficiency this this can become a monster amp.
But the first two actions do not improve efficiency.
Nelson hinted that he will double the efficiency in a later version. (withoud turning it into an aleph)
Since this is DIY and because I want to get better understanding of these circuits I also like to experiment and find out things for myself by trial and error .
So my ( for the experienced probably simpel) question of why my Aleph current source experiment didn´t work remains.
And heh wouldn´t it be nice If someone could come up wth a nice sollution to improve efficiency before Nelson does...
Alltough I would very much appreciate it if he jumped in
Thanks for your help.
I know that increasing bias will give more power and this will indeed become a balanced version. I also think that together with BBA3 and doubbling the efficiency this this can become a monster amp.
But the first two actions do not improve efficiency.
Nelson hinted that he will double the efficiency in a later version. (withoud turning it into an aleph)
Since this is DIY and because I want to get better understanding of these circuits I also like to experiment and find out things for myself by trial and error .
So my ( for the experienced probably simpel) question of why my Aleph current source experiment didn´t work remains.
And heh wouldn´t it be nice If someone could come up wth a nice sollution to improve efficiency before Nelson does...
Alltough I would very much appreciate it if he jumped in
Last edited:
I know teh general inefficiency of single ended amps. But in balanced configuration and double the efficiency this will be a killer amp
But can anyone help me out on the original questions
=why adding an aleph current source to just the buffer stage doesn´t work and results in an occilation?
=Which other options there are for increasing efficiency?
If Nelson knows how to do it there surely must be a way to do it
By the way here the quote from Nelson.
Later on Nelson said that turning it into an aleph would lack Novelty. ......
But can anyone help me out on the original questions
=why adding an aleph current source to just the buffer stage doesn´t work and results in an occilation?
=Which other options there are for increasing efficiency?
If Nelson knows how to do it there surely must be a way to do it
By the way here the quote from Nelson.
They are pure heat. This is a Burning Amp.
You will get a lot more efficiency out of BA#2, which is push-pull
instead of single-ended/constant current source.
If you want more efficiency out of the all-N channel output stages,
we will expect to be doubling the efficiency in a later version.
Later on Nelson said that turning it into an aleph would lack Novelty. ......
Last edited: