OLD DACs

[FallenAngel]

Hey guys,

So I've been playing with older DACs that I've snatched off eBay/AudioGon and I've got to say, these older units that sell for a tiny fraction of their original price are damn fine sounding units!

The one I'm currently listening to is the Aragon D2A. It is based on the PCM58 DAC running in dual-mono and has a discrete I/V and discrete output stage. Of course I didn't have a PSU for it but an hour of work and I now have a 2x LM317-based PSU outputting 2x24V to it. I haven't played inside it too much, just replaced the wiring with 75R coax and swapped one of the RCA inputs to BNC.

Considering I got this unit for barely $150 and tossed in a $75 PSU, I'd say it's a killer DAC at the price. The stock Zhaolu D2.5A has nothing on it! Modded, it might try to compare, but that's another story. Listening to it now, it definitely doesn't match up in terms of detail/resolution to the NorthStar m192 MK1 fed through I2S, but it certainly has a nice sound signature.

Now to try to describe what I hear (I always hate this part as it's completely personal and only relative to what I hear in other equipment and how I hear things in general).

Highs : Nice, nothing to write home about but certainly nice compared to a unit almost 10x it's price.

Mids : Oooh, can I have that again?

Sweet, so sexy sweet! Lush and beautiful, just beautiful!

Bass : Somewhat lacking in quantity and therefore not really able to judge full detail. I will say this though; I can still tell the difference between a synthesized bass note, a real bass guitar and a real bass. If you don't know what I'm talking about, you listen to too much "modern music" and just think this thing has little "bass".

I'll write another entry once I have spent more time with it and I'll write another about the Forte F-50a unit I grabbed off eBay ($225 shipped, but upgraded with 4x OPA627 - balanced DAC).

Just trying to stir up some nostalgic love for some "older but still kick-ass" DACs out there. I don't listen to "high-def" content nor do I see myself doing so anytime soon so why not buy wonderful $1000+ DACs at $200 prices!

Share your experiences and thoughts. Knowing this is the DIY forum (which is basically the only place I really hang around, post any mods you made to them).

 

[sachu]

very cool fallenangel...
am currently in the process of modding my DAC which is based on the PCM1704.

THe signal chain in the DAC is CS8414->DF1704->PCM1704->OPA627BP(I/V) -> OPA627BP(filter).

I am going to be replacing the I/V and filter with just an I/V stage and a class A output stage. It is going to be a Pass Labs D1 I/V stage clone.

Total cost is going to be about 90$ including separate PSU + transformer for the I/V.

Next would be to change the regulator for the receiver and interpolation filter with a discrete shunt regulator. Finally, change the reciever board out for the one sold by twisted pear audio which has 50ps jitter compared to 200ps on the current one.

Do post pics of your mods.

 

[MASantos]

Why are you using the bp version of the 627's? They only have better DC specs, audio is AC. You can save yourself some $ right there.

 

[sachu]

Quote:

Originally Posted by MASantos /img/forum/go_quote.gif Why are you using the bp version of the 627's? They only have better DC specs, audio is AC. You can save yourself some $ right there.

oh..i just had them lying around when i built this DAC over 3 years ago...they will go up on sale soon

 

[apatN]

Glad you like it. I see them pop up sometimes but I was a bit hesitant as I do know that technology has took a huge leap forward since those DACs were first introduced.

 

[fzman]

i think fallenangel is on to something here, and well worthy of comment.

seems like some people get caught up in looking at only one area of the design or a component, or just look at some simple numerical assessments of the behavior of a component and over-generalize, or make assumptions about why a specific piece of gear sounds good or bad. i've seen reviews on the web of sound cards that simply take that rightmark software as if it tells the entire story about whether a sound card sounds good or not.

people often get hung up about upsampliing, oversampling, 24 bit vs 32 bit, etc..... (or wther it's 7.1 8.1 0r 9.1 in the surround sound world) and infer that newer is better simply because it's the latest greatest chip set.

d-to-a converters are tricky business, because they require both analog and digital expertise, and overall design talent to get them right. lots of audiophile companies are good at analog, but not digital, and lots of digital engineers know squat about good sounding analog design.

all of this, i think, adds up to the fact that there are some "bit-challenged" dacs out there that sound great, and much better than the spate of recent asian budget gear. you've probably figured out by now that i am primarily a subjective audiophile, but do not dismiss engineering talent as vital to the design and manufacturing of great sounding gear, whether analog or digital...

this is all a long-winded way of recommending that people look at the total design before judging the merit of a (digital) component.

 

[Nemo de Monet]

I have to suspect that we're either at, or just past, the "quality peak" for DACs; from here on out; true quality - by any realistic measuring stick - isn't going to improve in any really meaningful way. Instead, DACs are going to become (more) commodified, so to speak - "built down" to an attractive price point, or made physically smaller, or built with on-paper specs, rather than real-world performance, in mind, or burdened with all kinds of wacky features that don't really belong in a DAC in the first place... much like what has happened with cellphones.

So, no, it doesn't really surprise me that there are some truly awesome bits of equipment out there, available cheap from people who've (foolishly) "upgraded" to newer models with, say, an industry-leading twelve blinky blue LEDs on the front panel and a fully-discrete Class-Double-Zed-Point-One output stage. Or whatever.

 

[nikongod]

Quote:

Originally Posted by Nemo de Monet /img/forum/go_quote.gif I have to suspect that we're either at, or just past, the "quality peak" for DACs; from here on out; true quality - by any realistic measuring stick - isn't going to improve in any really meaningful way. Instead, DACs are going to become (more) commodified, so to speak - "built down" to an attractive price point, or made physically smaller, or built with on-paper specs, rather than real-world performance, in mind, or burdened with all kinds of wacky features that don't really belong in a DAC in the first place... much like what has happened with cellphones.

I think we are well beyond that point.

During the race to *improve* DAC quality from "questionably adequate" to "good" there were some VERY nice sounding chips produced. Now that everyone can say they are at least good on paper the war for quality is over, the war for price is on!

I agree that a large part of the price war is how much stuff you can get 1 chip to do. When you look at compromises necessary to get EVERYTHING into 1 chip, as opposed to several components optimized to do their own thing the situation looks bleak.

The reason this trickles back to us is simple: nobody is building the old chips or anything like it anymore. The whole DAC chip building world is in a race of how much stuff can you get in a small package to save board space and external component costs. HI-FI audio has long been at the mercy of what is available mass-market style. You can get around some issues with some of the chips, sure, but it is horrifically difficult to build a dac for a small company or DIY'er. People have done it, but not ecconomically. They buy the mass-market parts and do the best they can or they just don't do digital.

 

[bhjazz]

I'd still like to get my hands on a Moth U-Dac. mmm.

 

[Duggeh]

My DAC is at least 20 years old and its bloody marvelous.

 

[TimmyMac]

Yeah, those old PCM chips are pretty popular still... people are putting together PCM63 DACs pushing 4-digits...

 

[FallenAngel]

After spending some more time with the Aragon D2A, I must say it's a really good sounding unit. My first test was unfortunately botched a bit by the wiring (both DACs outputting to the same amp splitter). I still think the clarity of the NorthStar is superior, but the bass is now no longer lacking in the Aragon and the mids are still very beautiful.