Hi all,

After quite a long absence, I'm starting to get back into messing about
with hi-fi again. And, as I've now got a secure e-mail base from which
to risk posting messages to the USENET again, here I am!

Anyway, to cut a long story short, I've finished making myself a
listening room here in Heidelberg and have my normal amplifier (one of
the big "20/20"s) set up with a choice of either ESL-57s or Monitor
Gold 15s. And yes, pretty much everything else I've built or acquired
is racked nearby! However, my main source is still - alas - a Pioneer
PDS-901 cd player from my student days. In other words, it's high time
I got around to building a proper DAC.

Cirrus Logic seems to have some promising all-in-one chips on offer.
Right now, I'm quite taken with the CS43112 and CS4397 as they offer
24-bit resolution and differential outputs. This should let me
transformer-couple (Lundahl LL1527?) the outputs directly to grids of
the 6J5s in my existing amplifier.

So far so good. Cirrus Logic further offers the CS8420 which appears to
be a combined transceiver / upsampler, meaning that I could use it to
decode a standard S/PDIF input into the PCM output the DAC chip needs
*and* upsample any given input signal to 24-bit, 96KHz at the same time
- an ideal situation for running both chips off an external master
clock. Should it be necessary, the CS8420 can also run off a PCM signal
- such as that from a CS8416 receiver.

Please through some helpful comments or suggestions my way!

Best regards from Heidelberg,

Russ Sadd

"Russ Sadd" wrote in message
oups.com...
Hi all,

After quite a long absence, I'm starting to get back into messing about
with hi-fi again. And, as I've now got a secure e-mail base from which
to risk posting messages to the USENET again, here I am!

Hello Russ,

Nice to see you back on RAT:-))

Iain

Russ Sadd wrote:

Hi all,

After quite a long absence, I'm starting to get back into messing about
with hi-fi again. And, as I've now got a secure e-mail base from which
to risk posting messages to the USENET again, here I am!

Anyway, to cut a long story short, I've finished making myself a
listening room here in Heidelberg and have my normal amplifier (one of
the big "20/20"s) set up with a choice of either ESL-57s or Monitor
Gold 15s. And yes, pretty much everything else I've built or acquired
is racked nearby! However, my main source is still - alas - a Pioneer
PDS-901 cd player from my student days. In other words, it's high time
I got around to building a proper DAC.

Cirrus Logic seems to have some promising all-in-one chips on offer.
Right now, I'm quite taken with the CS43112 and CS4397 as they offer
24-bit resolution and differential outputs. This should let me
transformer-couple (Lundahl LL1527?) the outputs directly to grids of
the 6J5s in my existing amplifier.

So far so good. Cirrus Logic further offers the CS8420 which appears to
be a combined transceiver / upsampler, meaning that I could use it to
decode a standard S/PDIF input into the PCM output the DAC chip needs
*and* upsample any given input signal to 24-bit, 96KHz at the same time
- an ideal situation for running both chips off an external master
clock. Should it be necessary, the CS8420 can also run off a PCM signal
- such as that from a CS8416 receiver.

Please through some helpful comments or suggestions my way!

Best regards from Heidelberg,

Russ Sadd

Hi Russ,

welcome back.

I am no expert on matters digital, but
are not the analog differential outputs current source
rather than voltage source?

If so, one may think a pair of follower buffers be used
between the DA outputs and transformer you intend using
in order to keep the source impedance driving the tranny low, since that
favours
low distortion from the tranny.

I'd have to see a schemo to better understand...

Patrick Turner.

Patrick Turner schrieb:
I am no expert on matters digital, but
are not the analog differential outputs current source
rather than voltage source?

It's differential voltage output - and Cirrus has been good enough to
post a full set of documentation at
http://www.cirrus.com/en/products/pro/detail/P147.html .

Best regards,

Russ Sadd

Russ Sadd schreef:
Hi all,

After quite a long absence, I'm starting to get back into messing about
with hi-fi again. And, as I've now got a secure e-mail base from which
to risk posting messages to the USENET again, here I am!

Anyway, to cut a long story short, I've finished making myself a
listening room here in Heidelberg and have my normal amplifier (one of
the big "20/20"s) set up with a choice of either ESL-57s or Monitor
Gold 15s. And yes, pretty much everything else I've built or acquired
is racked nearby! However, my main source is still - alas - a Pioneer
PDS-901 cd player from my student days. In other words, it's high time
I got around to building a proper DAC.

Cirrus Logic seems to have some promising all-in-one chips on offer.
Right now, I'm quite taken with the CS43112 and CS4397 as they offer
24-bit resolution and differential outputs. This should let me
transformer-couple (Lundahl LL1527?) the outputs directly to grids of
the 6J5s in my existing amplifier.

So far so good. Cirrus Logic further offers the CS8420 which appears to
be a combined transceiver / upsampler, meaning that I could use it to
decode a standard S/PDIF input into the PCM output the DAC chip needs
*and* upsample any given input signal to 24-bit, 96KHz at the same time
- an ideal situation for running both chips off an external master
clock. Should it be necessary, the CS8420 can also run off a PCM signal
- such as that from a CS8416 receiver.

Please through some helpful comments or suggestions my way!

Best regards from Heidelberg,

Russ Sadd

Is this what I hope it is?

I have been wondering if it were possible to build a tube D class type
amplifier. If I have heard right you amplify the PCM stream first and
then convert to analog via a tranny? Supposed to be efficient.

I hope this thread gets good. I'm listening.

Wessel

"Wessel Dirksen" schreef in bericht
ups.com...

Is this what I hope it is?

See it as a PP outputstage with the DAC as phase splitter / driver ....

Ronald .

Russ Sadd wrote:

Patrick Turner schrieb:
I am no expert on matters digital, but
are not the analog differential outputs current source
rather than voltage source?

It's differential voltage output - and Cirrus has been good enough to
post a full set of documentation at
http://www.cirrus.com/en/products/pro/detail/P147.html .

It appears they have a pair of outputs, each has 2.5mA in the Cmos output
devices,
but arranged for class AB to cope with driving loads lower than 2k.
So I doubt you have to buffer; it already is buffered.

There is enough quiescent current in the output amps to keep
these working in class A into loads above 2k; 2.5v swing into 2k is only
1.25 mA I change.
So any high Z load won't load down the chip.

There isn't anything else at the above site which I can understand.
BTW, ppl rtrying to go to the above address may have a bother since there
is a
dot after ".html" in the above address which stops the
address working; leave out the dot and it works.

Patrick Turner.



Best regards,

Russ Sadd

Ronald wrote:

"Wessel Dirksen" schreef in bericht
ups.com...

Is this what I hope it is?

See it as a PP outputstage with the DAC as phase splitter / driver ....

He could have all balanced to the tube amp PP output stage.
But he'd have to use a gain control someplace.

That'd have to be balanced too, but that's no problem using a dual gang pot
for each channel,
or a DACT 4 gang attenuator for both channels.
Then he'd just need an LTP balanced input amp driver, and a PP output
stage.
If he wants FB there can be balanced FB from the OPT secondary to the
LTP cathodes.
The only reason why one would use a tranny after the DA converter would be
to have a floating
pair of balanced outputs or a floating SE output, which should reduce hum.
I'd be wary about stray back emfs from the tube circuits to the DA. I'd put
in some diode clamps.

Patrick Turner.




Ronald .

In article ,
wrote:

On 27 May 2005 05:19:27 -0700, "Wessel Dirksen" wrote:

I have been wondering if it were possible to build a tube D class type
amplifier. If I have heard right you amplify the PCM stream first and
then convert to analog via a tranny? Supposed to be efficient.

Wouldn't work. You'd have to convert PCM to PWM - Pulse Width Modulation,
then control the amp with this signal and pass it thru a low pass filter.
Tubes aren't really adapted to PWM amplification, Mos-Fets are *much*
better.

"Tubes aren't really adapted to PWM amplification"? What about the PWM
modulator tube in the Harris MW-50 AM broadcast transmitter, that manages
to put out a peak power somewhere on the order of 390 kW, not too shabby
for a PWM tube audio amplifier.


Regards,

John Byrns


Surf my web pages at, http://users.rcn.com/jbyrns/

"Russ Sadd" wrote
...
Cirrus Logic seems to have some promising all-in-one chips on
offer.
Right now, I'm quite taken with the CS43112 and CS4397 as they
offer
24-bit resolution and differential outputs. This should let me
transformer-couple (Lundahl LL1527?) the outputs directly to grids
of
the 6J5s in my existing amplifier.
...

Hello Russ. Have you de-mystified your web pages yet?

Why transformer coupled? What are the issues with this switched
capacitor output?

What scares me is the layout and practical implementation, arranging
for proper isolation of digital and audio. The "simple" evaluation
board, with the two chips, power conditioning and analogue
filtering, has four layers. Then there's the control interface to
consider. You must be very brave or very clever.

Welcome back.

cheers, Ian

On 27 May 2005 01:52:29 -0700, "Russ Sadd" wrote:

Hi all,

Dude, where'ya been?

In other words, it's high time
I got around to building a proper DAC.

Cirrus Logic seems to have some promising all-in-one chips on offer.
Right now, I'm quite taken with the CS43112 and CS4397 as they offer
24-bit resolution and differential outputs. This should let me
transformer-couple (Lundahl LL1527?) the outputs directly to grids of
the 6J5s in my existing amplifier.

Please through some helpful comments or suggestions my way!

The pin 19/20 and 23/24 appear to be the DAC raw current outputs.
For a serious effort, this is where you'll want to start looking.

Remembering that current sources are only linear into virtual shorts,
you'll want to load these summing junctions with a very low impedance
at *all* frequencies, even those *way* above the sample rate. This
issue is the downfall of lots of inexpensive commercial stuff.

Two popular approaches have emerged: brute-force, shorting the DAC
output with a small resistor and amplifying;

And, B, some variation on the "grounded-grid" amplifier topo from
RF use. Perhaps surprisingly, these are identical from a noise
standpoint. Transformers, however, have no practical use here.
(Way! too big)

Good fortune,


Chris Hornbeck
"I didn't think this would happen again,
with or without my best intentions" -Liz Phair,
"**** and Run" from _Exile in Guyville_
Mean blues; not for the faint of heart.

Welcome home, Russ. We missed you.

Russ Sadd wrote:
Hi all,

After quite a long absence, I'm starting to get back into messing about
with hi-fi again. And, as I've now got a secure e-mail base from which
to risk posting messages to the USENET again, here I am!

When I returned, the first impulse of some parties on RAT of whom I had
never heard, and who had never once met me, was to say in public that
the first business of RAT was to find out my ISP so they could harass
it into throwing me off. Some of that gang are still here. I welcomed
the Net when it arrived as giving Everyman a voice...

I found using an anonymous remailer very tiresome. But Frank B, an
American motor engineer working in Germany, showed me how to use
proxies and recommended an automatic proxyfinder and this works
smoothly (at least on a Mac).

Anyway, to cut a long story short, I've finished making myself a
listening room here in Heidelberg and have my normal amplifier (one of
the big "20/20"s) set up with a choice of either ESL-57s or Monitor
Gold 15s. And yes, pretty much everything else I've built or acquired
is racked nearby! However, my main source is still - alas - a Pioneer
PDS-901 cd player from my student days. In other words, it's high time
I got around to building a proper DAC.

My own experiences are at:
http://members.lycos.co.uk/fiultra/DACjute.htm
You can ignore the text as irrelevant to someone who has ESL; it says
mainly that DAC work needs a high resolution chain, which you have, and
that I found DAC improvements of marginal utility to my pleasure from
music, which you are qualified to regard as matter of opinion upon
which you could possibly improve; in addition, suitable input and
output transformers, which were a pain when I did this a few years ago,
are now generally available. For your purposes the important bits are
the block diagrams, one of which lists the best components and the
other showing that I came to the same conclusion as you, that the
Cirrus Logic chips are the best bet. I liked the PCM63 too but they
were even further removed from value for money.

Andre Jute

Cirrus Logic seems to have some promising all-in-one chips on offer.
Right now, I'm quite taken with the CS43112 and CS4397 as they offer
24-bit resolution and differential outputs. This should let me
transformer-couple (Lundahl LL1527?) the outputs directly to grids of
the 6J5s in my existing amplifier.

So far so good. Cirrus Logic further offers the CS8420 which appears to
be a combined transceiver / upsampler, meaning that I could use it to
decode a standard S/PDIF input into the PCM output the DAC chip needs
*and* upsample any given input signal to 24-bit, 96KHz at the same time
- an ideal situation for running both chips off an external master
clock. Should it be necessary, the CS8420 can also run off a PCM signal
- such as that from a CS8416 receiver.

Please through some helpful comments or suggestions my way!

Best regards from Heidelberg,

Russ Sadd

Please through some helpful comments or suggestions my way!

I did some work with transformers driven by DAC chips he
http://pw2.netcom.com/~wa2ise/radios...c.htm#transdac