JC Fardo said:
In original BOZ, Mr Pass used ( even if only last '0' is visible in schema)
10 uF into 5 kohm.
This gives, 10x5 = 50kuF.
To keep same frequency roll-off as Nelson Pass (and if it is good enough for him ... )
we keep kOhm x uF = 50
Now using a 10 k potentiometer, we get the cap would be:
50 / 10 = 5uF ... which is one 4.7uF
10k x 4.7uF = 47kuF
which is practically equal to 50. (A few % + or - is NOTHING in these matters)
-------------------------
In other words,
if we double the pot value, we can half the cap value
and the frequency roll-off stay exactly the same.
And if we use a 47 or 50 kOhm pot instead of 5 kOhm
we can make cap 10 times lower = 1uF
And
50 kOhm x 1 uF = 50
just as
5 kOhm x 10 uF = 50
lineup - plain simple math
Tyimo said:Hi JC!
I think Mads and Lineup wrote everything what you need to know!
I have to say thanks for Them too!
Tyimo
Absolutely! Ultimate thanks to all. I´m just not confortable to get on in this SEWA thread, but T-BOZ is way from the first version as mine. The BOM is getting large as far as I read the posts and schematics.
Is there any starting T-BOZ article from you or Mads or Lineup somewhere? I´ll post a new thread if more questions come up.
JC
Re: Power DAC for SEWA Dreams
There are plenty non oversampling DAC projects, both here in forum and in web.
I have come across quite a few, when surfing.
But I have never heard of a DAC with such high voltage output.
But sure would be possible to build such.
It would have some I/V, current to voltage amplifier
that has more voltage gain than normally.
In the Digital Forum
they surely should know this better.
Power DAC is this a new Tyimo invented word for such a converter.
Or is this an already known word for these ???
lineup
Tyimo said:
Would it be possible to design a Power DAC for the SEWA?????
I mean a non oversampling DAC that has enough power to direct drive the SEWA.
No preamp just a buffered (maybe tube....) DAC with 11V RMS output and the SEWA!
That would be
There are plenty non oversampling DAC projects, both here in forum and in web.
I have come across quite a few, when surfing.
But I have never heard of a DAC with such high voltage output.
But sure would be possible to build such.
It would have some I/V, current to voltage amplifier
that has more voltage gain than normally.
In the Digital Forum
they surely should know this better.
Power DAC
is this a new Tyimo invented word for such a converter.Or is this an already known word for these ???
lineup
Re: Re: Re: Power DAC for SEWA Dreams
Maybe it would be a perfect tube job.
for those who master tube circuits.
But also good OP-Amp possibly with a couple of transistors for increased output capacity.
But I really, on second thought, question the benefit of this idea.
So where to put volume control?
If you have 10 V RMS output from DAC.
Would you put a pot at DAC output,
and attenuate the voltage level you just have amplified ...
This is never a good idea.
First to amplify, with the distortion that always more or less comes with voltage amplification.
Then to take this signal back to low level.
We should only amplify voltage when we really need it.
The only way around this,
is to make the DAC circuit have a variable gain option,
between 1-10 for example.
The good thing with CD-players DAC output is at 'line-level', max 2.0 V RMS
is that devices, like often headphones, or passive pre amplifiers,
can use this signal directly
without any amplification and further distortion.
lineup
planet10 said:
Maybe it would be a perfect tube job.
for those who master tube circuits.
But also good OP-Amp possibly with a couple of transistors for increased output capacity.
But I really, on second thought, question the benefit of this idea.
So where to put volume control?
If you have 10 V RMS output from DAC.
Would you put a pot at DAC output,
and attenuate the voltage level you just have amplified ...
This is never a good idea.
First to amplify, with the distortion that always more or less comes with voltage amplification.
Then to take this signal back to low level.
We should only amplify voltage when we really need it.
The only way around this,
is to make the DAC circuit have a variable gain option,
between 1-10 for example.
The good thing with CD-players DAC output is at 'line-level', max 2.0 V RMS
is that devices, like often headphones, or passive pre amplifiers,
can use this signal directly
without any amplification and further distortion.
lineup
Yes, the resistor at the bottom of the cathode follower should really be a CCS or choke... this dramatically improves the CF (i've updated the drawing). You could also -- to good effect -- add a CCS to the anode of the CC stage.
Also since it is only 2 stages you could leave out the last RC decoupling stage in the supply rail.
dave
Also since it is only 2 stages you could leave out the last RC decoupling stage in the supply rail.
dave
Hi JC!
You need for start only Mads BOZ schematic (post 573) and PCB plan(post574-575) and BOM(some earlier post). Nothing more.
Use 2SK216 instead of IRF610. Note the different pins of the 2SK's :GSD.
Use the different setup or bias like me and as I wrote already.
Hope this helps.
Greets:
Tyimo
You need for start only Mads BOZ schematic (post 573) and PCB plan(post574-575) and BOM(some earlier post
). Nothing more. Use 2SK216 instead of IRF610. Note the different pins of the 2SK's :GSD.
Use the different setup or bias like me and as I wrote already.
Hope this helps.
Greets:
Tyimo
I was perhaps a bit sarcastic, but it wasn´t meant as a joke.
A 50W SoZ consumes 1200W per channel, just for reference.
With some kind of forced cooling (water or fans) it wouldn´t be too hard to manage. Reliability would be an issue though, if the fans or the waterpump breaks you will face meltdown within minutes or even seconds.
Not that I can see any point in such a project, if I felt that I needed 250W I´d change the speakers to something more sensitive instead.
A 20-25W SE follower OTOH would be a fully realistic project, the 100-150W of losses per channel wouldn´t be a problem for a pair of good heatsinks. Spreading the heat by using multiple Mosfets would probably be a great idea, same thing with putting a lot of effort into mounting them correctly on the heatsinks.
40V and 3A should be enough for just over 20W into 8 ohms.
Since I´m more interested in current capability than max power into a resistive 8 ohms load I´ll go for 32V rails and still pull 3A through the mosfets.
Another possible explanation to my choice of voltage and current might be that I have some 24VAC transformers and a couple of 3A chokes in the junkbox
A 50W SoZ consumes 1200W per channel, just for reference.
With some kind of forced cooling (water or fans) it wouldn´t be too hard to manage. Reliability would be an issue though, if the fans or the waterpump breaks you will face meltdown within minutes or even seconds.
Not that I can see any point in such a project, if I felt that I needed 250W I´d change the speakers to something more sensitive instead.
A 20-25W SE follower OTOH would be a fully realistic project, the 100-150W of losses per channel wouldn´t be a problem for a pair of good heatsinks. Spreading the heat by using multiple Mosfets would probably be a great idea, same thing with putting a lot of effort into mounting them correctly on the heatsinks.
40V and 3A should be enough for just over 20W into 8 ohms.
Since I´m more interested in current capability than max power into a resistive 8 ohms load I´ll go for 32V rails and still pull 3A through the mosfets.
Another possible explanation to my choice of voltage and current might be that I have some 24VAC transformers and a couple of 3A chokes in the junkbox
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