DACing Off

[Icarium]

I thought all double crowns were S2, is this not so? Not a TDA1541 aficionado or anything.

I think that might not entirely be the case.. also there's some weird shit about where they are manufactured and stuff too. Well with the new pics I need to look at the chips I have and see how real they look ;p

[Dusty Chalk]

What in tarnation is a "double crown"? I thought that was a checkers move.

[cetoole]

Crowns are the symbol of higher grade parts, and double crown is the highest grade. Pretty rare.

[Pars]

What in tarnation is a "double crown"? I thought that was a checkers move.

They are just graded TDA1541a's. In other words, tested and verified to meet certain specs, and then sold at a premium (and now faked). Since they didn't test all of them produced (I presume), it is possible to get a TDA that performs as well as the single or double crowns, but just isn't marked (and can't be sold on fleabay for $200+).

[atothex]

Yeah, but how good are even top-notch TDA1541A? I assume good but not exactly great in the grand scheme of things?

[Pars]

They are still highly thought of in many circles. 16-bit R2R DAC. Thorsten Loech chose it for his commercial DAC (can't remember the name of the company) even though they have been out of production for a decade. Just because it is old doesn't mean it isn't good. The primary reason that R2R dacs (multibit) aren't done much anymore is cost as it is expensive to laser trim all the resistors on the die.

[diebenkorn]

Loesch's company is Abbingdon Music Research - Home Page

The zanden uses it as well.

[Currawong]

Doug: Sorry to hear about the R1. I feel your pain.

Are there any R2R DACs in production other than the PCM1704 currently?

[feckn_eejit]

what, no love for bass that's like a fat black woman shaking her booty?

no. i like it deep fast and tight. and you can read whatever you like into that. "PRaT" is king. (note to self: check out naim dac when it lands at local dealer...)

that's one reason I really really like the SFD2 mk2. the bass doesn't turn on a dime.

if you listen to stand-up bass in jazz tracks it sounds more real.

if you need fat bloaty bass in your playback to make instruments sound "moar real", then the recording isn't good enough IMO......

Most important 1st question: Is the Pass 230V switchable?

Would require a visit back to Pass to change a few components

I'm trying very hard not to get that Pass.

Stop that... it's on HF now but the Casino deal still applies........ i've been listening to this thing unbalanced at my desk two days now and am seriously enjoying it but it's nuts for me to have so much tied up in sources right now............

[Duggeh]

Esoteric D-07.

Please report back!

Don't tempt me with things that cannot be bought!

[dreamwhisper]

no. i like it deep fast and tight. and you can read whatever you like into that. "PRaT" is king.

interesting, we definitely have different taste

I go more for overall musicality, layering, detail, resolution, 'real' sounding (funny because other than jazz I listen to alot of electronc music)

these things create a lot of the effects of prat imo, for me its similar to suspending disbelief when watching a movie

the tubes in the output stage do distort the speed of the bass somewhat, but it's a colouratin I can live with

the bass imo isn't not tight, like it isn't loose or anything

and I imagine it just gets better with the mk3

I like it because it creates a solid structure on top of which the rest of the music resides, it's like structural integrity, a foundation.

it is also important to me that the bass sounds somewhat natural, not like the ad2000's bass which is whiplash fast and definitely turns on a dime

also the midbass doesn't infiltrate the midrange, but helps creating the foundation

if you need fat bloaty bass in your playback to make instruments sound "moar real", then the recording isn't good enough IMO......

not sure what you mean by playback, im thinking you mean source material.

don't get me wrong, the sfd2 mk2 is prbly the most transparent source I've ever heard.

i think it's bass 'colourations' just make it sound more evenly balanced

it's actually ironic, because it's the only source I've ever heard that has tubes.

(I always thought tubes = coloured)

I really should just keep the damn thing, considering I would only be selling it to buy your mk3 later on anyway

[dreamwhisper]

yeah the bass is interesting,

I can hear the origin of the note (the attack) and it as tight as the next high-end source

maybe even tighter than some, because it extends so deep it creates an illusion of greater speed

but the tube bloom distorts it in a weird way, so it isn't as tight as solid state

isn't as crispy

I'm only using the Mackie monitors and no sub tho

I'll report back when my Adam sub gets here

[Duggeh]

Anyone have any experience with the Chord DAC64?

[Hopstretch]

I think Elephas had one and sold it.

Please take one for the 'Case and get the Naim DAC!

Edited October 3, 2009 by Hopstretch

[dreamwhisper]

two posts today about nothing... I'm an idiot, thinking I know anything about the bass on the sfd2mk2 without hearing it with a sub...

interesting, we definitely have different taste

lol, just realised that we may be talking from two different approaches

I use my sfd2mk2 with my speaker rig, where I think it is exceptional

with headphones, I agree, PRaT reigns supreme, and the sfd2mk2 didn't impress me that much. In fact, I prefer the Parasound's solid state PRaT with headphones.

[feckn_eejit]

Yup... like I said I prefer the SF to the D1 on speakers, and the D1 to the SF on headphones...

[Duggeh]

The modded DAS-R1 now turns on. I discovered this as I flicked the power button a couple of times in esasperation as I was going to box it up.

There is no possible explanation for this magic cure. I've done nothing to it since it first failed to turn on.

*Twilight Zone Theme*

[swt61]

Well you're not that far from Ireland, a stray leprechaun perhaps?

[dBel84]

Finally modded the I/V for my transdac

home jigged smd adapter for the THS4031 and NOS siemens bypass caps

sounding good , but then I really liked it stock so will need moar time to tell. The Leak 3000 seem to have more punch in the bass and soundstage but I haven't used them for a bit and they may sound this way all the time

..dB

[cetoole]

Don, definitely a good idea to get that on an oscilloscope, those THS4031 love to oscillate. I currently see like 5mV at 5MHz on the output of mine, and more on the output of the AD797 stage.

[dBel84]

thanks , will haul it all out and test when I get some time..dB

[some1x]

Doug: Sorry to hear about the R1. I feel your pain.

Are there any R2R DACs in production other than the PCM1704 currently?

MSB Platinum DAC, MSB Power DAC, and Lavry DA924 come to mind. They use discrete R2R DACs.

[deepak]

What's inside the DA924 (or DA2002)?

[some1x]

I believe it is a custom R2R DAC. One of Lavry's cool features is that it uses "oven" to calibrate the resistors. If I understand it correctly, the Lavry will dynamically adjust the resistors on startup.

From the manual:

A sequence where each resistor is tapped (one at a time) for voltage comparison against a

reference level tells the processor the required adjustments. The voltage difference between any

given network node and the reference is greatly amplified and then fed to a strobing comparator

(see multiplexers for calibration and error amplifier and comparator gain blocks in the simplified

diagram). The processor strobes the comparator and reads its output. The strobing is repeated

4000 times for the sake of averaging out any error due to amplifier noise. At the end of a

comparator strobing cycle, the processor decides whether to increase or decrease the specific

voltage of the measured node. This is done via the calibration 14 bit DACs (see diagram). Each

calibration DAC is used as a 13 bit device to ensure monotonic performance. Each DAC is fed to

its corresponding node through a large value resistor, thus a full 10V swing on the calibration

DAC can only pull a given node by +/-4mV, providing an effective adjustment of a part in 5

million per calibration DAC step.

DA924 Operations Manual

10

The calibration process takes a long time because the node adjustment is interactive (adjusting a

node causes some misadjustment at all the other nodes). A single calibration cycle consists of

reading and adjusting of all the nodes. The processor repeats the calibration cycle numerous

times until all the nodes are set properly. Though nodes interaction exist during the adjustment

process, the overall network is guaranteed to converge on a solution by design. Calibrating a

DA924 for the first time (at the factory) often exceeds 25 minutes. Once calibrated, the settings

are stored in non volatile ram for future startup point of reference, thus all future adjustments are

initialized to the last settings. Therefore the initial tolerance of the components is pre calibrated

already, and each new calibration needs to deal only with component drift under the same given

temperature conditions (ovenized components). The remaining calibration at each subsequent

power on takes less then 2 minutes typically.

[Currawong]