Experience with this DIY DAC ?

[Segran]

It just hit me that the lack of low pass filtering is (partly) solved by using a transformer, as transformers have limited frequency response. The Lundahl LL1690 goes to 100kHz within 1dB, they say nothing about how steep the drop is. It doesn't matter since we are limited to what our ears can hear anyway!

I too try to keep an open mind to all these, sometimes imaginative, claims of the sonic impact from various components, but burdened by being an engineer I prefer having facts to base my belief on. My lack of imagination may also be the result of experience (or old age if you like).

BTW, Lundahl is a swedish company so I have nothing bad to say about them and their products!

[legarem]

The transformers were placed on a dac that played since 3 months.
In this case, forget the theory of breaking in of the caps.

When I had the transformers one of my friends and I listened them and the sound didn't have bass, proeminent mids and it was harsh.

I sent an email to Kevin Carter K&K Audio who distributes Lundahl in North America and I gave him my impressions about the sound. He told me that Lundahls take a lot of time to play correctly. 100+ hours.

As they were unlistenable, I placed a pink noise cd and let it play for one week.

After this week, This was night and day. I called my friend who agreed with the new results and we ordered another pair for him. Since that time, I ordered 3 other pairs for dacs I sold to friends.

Engineers have to look at good numbers to believe something.

I'm a pratician and I do real testing. Forget numbers and heat your soldering irons to TRY instead of trying to explicate anything with theory.

[legarem]

Originally posted by Segran
Hi legarem,
in the "lampizator" web page you have written "OP AMP BIASED MORE IN CLASS A", I guess you are referring to the 14k7 resistor from +12VDC to the output, after the 1k resistor. Please explain how this added resistor affects the biasing of the op amp. In my view, it's merely compensating for the (in your case obviously negative) offset at the output of the opamp by adding a small positive voltage to the output after the 1k.


The resistors are only there to have 0 V at the output.


Well, this is what a few of us have done by re-designing the low pass filter, and IMHO with excellent results!



I have no reason to doubt your first statement about the lundahl transformer, but as an engineer I truly doubt that transformers need "breaking in"! Can you substantiate that claim with any scientific facts or theory?

See my last message. You probably doubt because you're an engineer. You have to see good numbers and long thories to believe something. Try and talk after experimenting.

I have read about the LM4562 so I decided to make an adapter so I could compare LM4562 in one channel and NE5532 in the other. I haven't got to actually do the comparison yet. I don't really want to debate about "breaking in" op-amps, as I haven't seen any scientific rationale for how this would or could change the sonic impression. I would be more than grateful if anyone can show som evidence for this.

Read about this topic in Head Fi and many other places

In what way does the Sumlink affect the sound?

The sound is mellower with an even better soundstage.


I have asked in an earlier post if anyone tried it, and I guess you have. Can you describe in what way the sound improves as a result of the lower kitter in DIR9001?

I will talk again with experience not theory.

The DIR9001 gives better soundstage and larger image than the CS8416 which appears lacking details. The DIR9001sometimes has incisive sound with some cds. I have to work more around the DIR9001 to tame whats disturb me about the sound.

[legarem]

Oups

I had some problems wit the quote lines

You have to read between lines

[Mush]

About 15 years ago I was buying a tube amplifier form a PhD candidate at our electrical engineering department. It was the weirdest transaction I have ever taken part in. As I was asking questions about the amp, the seller couldn't stop insulting me for liking "noise in the circuit" and believing all the esoteric hype about tube equipment. When I asked him if it was stupid to buy the amp, he answered in the affirmative. I can't forget just how rude he was, but he was convinced that he knew the truth.

Several years later I read an article in Glass Audio by the excellent (and former Tektronix engineer) Lynn Olson on why tubes sound so good when used correctly.

I have learned the hard way the numbers and simulations are often incomplete. If numbers could predict everything, you'd probably be able to prove Vishnu's existence on a chalk board and all of math professors of the world would be eating chapatis right now. (they probably are anyway)

My suggestion is to try it. It doesn't look like a huge amount pf work. Try the circuit and trust your ears. Let it "break in". (I can't explain why, but stuff takes time to sound better) Tell us what you think of what you hear, not the numbers, but what you really hear.

Life is hideously short. We only get to discover things about this universe for a very few years.

[legarem]

Originally posted by Segran
Hi legarem, you wrote in post #101:


I have simulated your proposal and agree that it doesn't roll off any highs, in fact it doesn't work as a filter at all. If anything, omitting C32/C33 makes it prone to oscillate at around 0,5 Mhz.

I still put my money to the filter designed by Crystal and discussed in a few of the previous posts by me and Kevin, it does exactly what it is supposed to.

1.87K with 1n cap gives 85.1 khz at -3 db

Oscillating op amps is often due to poor power supply layout

0.01 to 0.1 caps placed between V+ and gnd and V- and gnd
NEAR the op amp often cure this problem

[legarem]

Originally posted by Mush
About 15 years ago I was buying a tube amplifier form a PhD candidate at our electrical engineering department. It was the weirdest transaction I have ever taken part in. As I was asking questions about the amp, the seller couldn't stop insulting me for liking "noise in the circuit" and believing all the esoteric hype about tube equipment. When I asked him if it was stupid to buy the amp, he answered in the affirmative. I can't forget just how rude he was, but he was convinced that he knew the truth.

Several years later I read an article in Glass Audio by the excellent (and former Tektronix engineer) Lynn Olson on why tubes sound so good when used correctly.

I have learned the hard way the numbers and simulations are often incomplete. If numbers could predict everything, you'd probably be able to prove Vishnu's existence on a chalk board and all of math professors of the world would be eating chapatis right now. (they probably are anyway)

My suggestion is to try it. It doesn't look like a huge amount pf work. Try the circuit and trust your ears. Let it "break in". (I can't explain why, but stuff takes time to sound better) Tell us what you think of what you hear, not the numbers, but what you really hear.

Life is hideously short. We only get to discover things about this universe for a very few years.

You're damn right with this message.

Being a tube lover since over 30 years, many peoples laughed when they saw these obsolete bottles in my basement.

Those who took the time to listen changed their minds.

Like many, I hated transformers but one night after trying old line transformers for fun with this dac I HEARD something that was right.
I forgotted my vision about transformers. Who cares ? the sound was the best I heard !

In this hobby we have to keep open minds if we want to do better and better things.

Many peoples are reading and listen others. There is also those who try by themselves instead of taking everything like cash.

[Segran]

This discussion is a no-win situation for everyone involved, since it is about believes and opinions. Subjective listening tests, and to make it worse done in intervals of hundreds of hours doesn't account for anything else than just opinons. It might even be changes in the barometric pressure that's affecting one's hearing or speaker response as far as I'm concerned. To do a comparison that's worth the effort you have to listen to both "new" and "burned in" at the same time and do ABX switching. So I'll bugger the ****out from that discussion after this reply.angel:

Thanks legarem for you reply on DIR9001. It sounds (!) like it's worth a try.

I actually am a "practician" and spend more time with my soldering iron than doing computer simulations. However, simulations are extremely helpful when "trying" different ideas so you know if you are going in the right direction or not. The first solution offered on Lampizator is, what I would say, - not.

As for your filter design, you have to consider the whole circiut and not only the 1k87/1nF. The frequency response of the WHOLE circuit is attached below. Note the phaseshift in the mid range. THAT is more than likely to be audible.:

I'm sorry if I have in anyway offended you, legarem. We simply are of different religions and opinions about some things. I was only asking for some insight knowledge to the burn-in question.

And Mush, I also believe that different designs sound different. I have proven that to myself by designing and building power amps using both BTJ and MOSFET outputs just to learn if they sound different. They did. I like MOSFET, but others like BTJ. That's just a matter of opinion and preferred taste!

And that as my 2 cent's worth.

[legarem]

Originally posted by Segran

I'm sorry if I have in anyway offended you, legarem. We simply are of different religions and opinions about some things. I was only asking for some insight knowledge to the burn-in question.

No problems at least you're open to try

[ah-luo-ko-ko]

All .. suggest stick to the DAC mod for this thread .. let try different things, document the mods for those who are not as handy ..

Listening is somewhat "subjective" -- eye of the beholder ;-)

I have buddies who are into the very high-end stuff. But whenever after having listened to their systems, I always like my system 'better' which are made up of mostly modified/DIY components. In fact, a buddy who owns a system based on B&W 801 driven by Bryton mono amps system is somewhat surprised (presently) when he listens to my system.

My wife and I visited a high-end store just two weeks ago and listened to a system using the limited edition Dynaudio 30th anniversary speaker (retailed for 20+K just for the loudspeaker). When we walked out of the store, both my wife and I think that that 'system' is 'thin sounding' and 'artificial' :-))))

The fun with DIY is the mod challenge, try to get the 'best' by building from scratch or mod a low price kit, share the experience and have fun ..

Let's continue trying the different mods and share your experience.javascript:smilie('')

Cheers.