Do we need Zobel with chip amps?

[Jamh]

Out of curiosity, does anyone know if the Zobel is there in the original 47 labs gaincard?

[netgeek]

I have to agree with Fred on this point... Having worked as an applications engineer (many years ago) I can't count the number of times that some customer ran into problems by failing to simply read the datasheet, tossing out critical components, or making certain "improvements" without understanding the core design. I tend to put alot of faith in the original designers and, therefore, the application notes they write. National - and the other major manufacturers - are not in the habit of hiring boobs and there's usually a great deal of thought, planning and effort that goes into the support materials provided.

If anything, if the choice of adding or subtracting a few components in a reference design comes down to a coin-toss - they WILL leave it out because it makes the product appear to be more streamlined, lower cost and easier to implement. So you can be fairly certain that if something found its way into the app-note schematics - there's a damned good reason for it. As Fred points out - it's easy enough to not populate a few components if you feel you don't need or want them - but it's a pain to start hacking and improvising if you find that you DO need them. It's a small amount of PCB area and a few more holes - so "why not"?

As for the argument that there are "hundreds" of DIY chip amps out there without problems - even a 'couple thousand would be statistically insignificant in the semiconductor world...

Bill

[leadbelly]

netgeek,

I think you hit the nail on the head. There's a big difference between saying "thou shalt build thy chipamp with a zobel" and recommending that pads be there on the PC board.

And although nothing to do with audio, I was an application engineer for many years and can never forget how many customer problems were things that were addressed in the spec but got ignored. I have been on both sides of the fence and also seen where manufacturers have intentionally put an ultra restrictive spec in place to thwart any warranty claims. But I don't think that the Zobel falls in the latter category.

[Philo]

Well, the designs in app notes are not neccessarily the best for every application. They're are configured to work in most applications dealing with many variables. These designs would have to be as stable as possible in order to promote a good product. That is the designs ultimate use... earn the company money and not neccessarily give the purchaser a marketable solution. Now, having said that, this line of chips was not designed to be an audiophile grade product. It was designed to put audio in TVs, powered speakers and compact components. Removing components, or even adding them for that matter, to many designs can improve the sound when used in a particular setup. Mr. Pass, a proponent of minimalistic designs, can attest to that statement. Which one is the correct method is entirely dependent on the builder's preferences. If he feels his design will sound acceptable and will sell it his choice alone to use(or not use) the components. A money making design with a suitable track record says alot for Peter's statements. His statement says he has yet to discover any malfuncation in his design warranting the addition of the Zobel. No one is disputing your expertise Fred, just your tact. "A well intoned whisper can make a point better than a shout".

[netgeek]

Originally posted by Philo
Well, the designs in app notes are not neccessarily the best for every application. They're are configured to work in most applications dealing with many variables. These designs would have to be as stable as possible in order to promote a good product...

A money making design with a suitable track record says alot for Peter's statements. His statement says he has yet to discover any malfuncation in his design warranting the addition of the Zobel. No one is disputing your expertise Fred, just your tact. "A well intoned whisper can make a point better than a shout".

You make some good points here. The app note designs are - in many cases - geared towards a particular customer or a particular market and may not address all of the applications for which the product may be used. But I can assure you that they are at least configured to provide some level of guaranteed and stable performance despite MANY variables. In other words, the intent is usually to showcase the benefits - and maximize the performance achievable - regardless of the application/customer. In simpler terms- the manufacturer wants to cast as wide a net as possible. For DIY - it needs to be bulletproof - so add the Zobel...

As for the money-making aspects- Delorean (for example) made money personally - but did his "customers" benefit? No. So the ability to suck in $$$ doesn't necessarily mean it's a great product or design (just look at Bose.. )...

Finally - as for Fred's tact- I'm not touching this! Folks on this forum will have to decide for themselves whether Fred's expertise (which appears to be considerable) will outweigh their inclination to turn him off because of personal bias or "chafing"...

Regards,

Bill

[Philo]

Bill,
I agree with your statements for the most part, but... most often not every benefit of a component will be realized in one single design. NS may have decided to "give up" some of their amp's acoustic performance for a design of greater stability. Remember what they were designing the chip for- IMO, good but affordable performance in a TV or compact stereo. My point being, Peter may decide to foresake the possible benefit of the Zobel's stability in order to realize the sound he is attempt to achieve from his design. Which way he decides to go is entirely up to him and ultimately his customers.

Oh yeah, I definitely agree with the Bose statement. Excellent example to your point.

[Fred Dieckmann]

"Removing components, or even adding them for that matter, to many designs can improve the sound when used in a particular setup. Mr. Pass, a proponent of minimalistic designs, can attest to that statement. Which one is the correct method is entirely dependent on the builder's preferences."

Interesting that you mention Mr. Pass...... The A40, A75, the Stasis2 .......... HAVE ZOBEL NETWORKS! I believe even Mr. Pass had to learn that the hard way when the Cobra cable (one of the first specialty speaker cables and very capacitive) came on the market and blew up quite a few amps including a few Thresholds.

Yes, it is the builder's preference to leave critical circuit components out of a design. Ignorance is bliss, and far be it from my to rob anybody of the bliss of an oscillating amplifier. It is quite interesting to me that the people so eager to leave the network out don't seem to have the slightest interest in what the thing actually does. It would take about 3 or 4 sentences to explain, but why bother when people have made up their minds without any interest in how an amplifier works. It's just a chip amp after all and doesn't require any knowledge of electronics to build, well it wouldn't if you actually followed the recommendations in the data sheet.

[Philo]

Fred,
I never said you were wrong about including the Zobel in the circuit if the amp oscillates, just overly indignant and somewhat hostile when someone doesn't agree with your points. And yes, Mr. Pass includes Zobels in his circuits that require them. But I believe he would tend to leave them out if he felt the sonic benefit from their ommission outweighed their usefulness in the circuit.
Alas, I am sorry to BrianGT, Peter and the other readers for dragging this thread off topic into the mud.

[Peter Daniel]

Originally posted by Fred Dieckmann
But your the amp designer..... I guess you know best as usual. What do I know I am just a lowly EE who actually listens,measures, and advocates consistent performance and reliability . And, BTW I have been building and designing audio for about 30 years and was using parts that you seem to think are new discoveries, ten years ago. But then again I am not part of the Chip amp cult were building a circuit from the ap notes (and not even doing that right sometimes) in the data sheet makes one an amp designer.

That is a typical comment from Fred.

Well, you may have been using the parts I've never heard of, 5 years ago. You may be building and designing audio for about 30 years and you may be a great EE. But so what?

Does this mean that I always have to stay in your shadow and listen to your words of wisdom? Did it ever occur to you that you may simply have nothing new to say? That you are always comming back with the same issues?

Did I ever presented myself as an amp designer? I don't remeber that moment. I rather envision myself as chassis designer, and that you shouldn't be questioning. While it happens that those chips are pretty handy with feeling empty spaces inside those chassis, you can't blame me either.

Does it really matter what parts you were using when I didn't even know what they were meant for? Does this mean you can built a better chip amp? Do you have to make fun of people building amps using those chips, calling it a cult and describing as building a circuit from the ap notes? If it works, what's wrong with it? Shouldn't those people be regarde as a lower grade of audio designers, because they don't show enough creativity with complicated circuits ?

If a customer whom I sold the amp replies that this amp is the best he had in his 25K system, do I have to look into dicreet designs? I've built quite a few class A discreet amps, but I don't even use them, as the chip amps sound better to me. I still have those big amps, but I don't remeber when was a last time they were on. Do you think that I'm in it only because they are easy to build?

I'm in it because I always wanted to be an amp designer. However my background wasn't in electronics. At certain point in life I made an improper decision and I went into mechanical field. After first year I already new that it was not what really interests me, but anyway I didn't change it. Eventually, it came to a point that I hated it so much that I decided to defect a ship in Germany ( as I was a ship mechanic apprentice at 4th year of my studies).

So I was there, on the streets of Keel, with a bag in my hand and brand new life ahead of me. I was 25 at that time. Well, the time I spent in Austria waiting for Canadian residence, was one of the best in my life, but everything that is good ends up quickly and I took up a job as an aircraft technician after arriving to Canada. Well, again not what I liked to do, but since it payed well, I couldn't complain. I was in and out of aircraft industry for years, majority of time not working at all, doing some odd jobs and even exporting cars to an Eastern block for a while, yet I was never happy with what I was doing.

Then I discovered this forum. Slowly, my early interest in electronics started to grow. I picked up an odd user name, as I was sort of afraid to make fun of myself. It was inspired by HarryHaller's name, as that guy seemed to be fun at that time.

But slowly, my confidence was growing. I noticed that I'm capable of doing certain things much better than others and I also noticed that my listening abilities were not that bad, and that what I was reading in Stereophile could actually be true. As everybody else, I was building Alephs, after all, it was the best thing around (to build). I came across a raving review of some strange looking amp called GC, but I didn't know what was inside and I didn't believe it could sound as good as they say. I even came across a thread selling toroids to Gainclone (I think it was Dave from whom I heard that name first). Later I notice Fedde's Gainclone page and slowly my interests grew. There were few guys, who built that amp and were showing the pictures on this forum, yet from their comments you couldn't figure out if this amp was really good. Well, I guess at that time the inside pics of GainCard appered somwhere and I also came across Thorsten schematic, and then I new I had to build that weired amp.

To be continued....

[Peter Daniel]

As you all probably know, it was a not another thread, that actually popularized GainClone amp on this forum. It wasn't me, it were people who made it the second largest thread, after Aleph X thread.

Well, to me, the GC amp didn't really seem to sound that good on a first day. I was toomuch conditioned by the sound of other amps. I used all the best components to build it, not because I new why to choose them. It was mainly because a friend of mine came back from HongKong and brought back a bunch of Rikens and Black Gates. At that time, I was at Holco stage and I was mostly using cheaper electrolytics, you know the stuff one buys at surpluss stores. I decided to use a similar chassis to what 47Labs were using. First, it seemed easy to build, secondly it looked cool. I took this amp to two of my audiophile friends, the guys who came across most upper end equipment and new the good sound. What encouraged me was that they didn't dismiss the amp ( as a side note one of them dismissed my Aleph5 right away, the other one wanted me to built an Aleph for him). I left the amp with one of those guys for few weeks and in a meantime got a proposition from a Swedish member to built an amp like that for him to. So I built it.

I got response from the first guy that was using my GC amp, and he commented that this is actually one of the best amps he heard. He was using Lumley monoblocks at the time (model 150). We met few times for listening sessions and indeed the amp sounded great. In the meantime I got rave response from a Swedish member, who was also very happy with my amp. So we started to build them and sell (we planned a CD player as a first product, yet it happened that it was to be an amp). We made our first appearance at Montreal Show, then we got review and the controversy started. At that time I was almost convinced that my amp was one of the best out there and that my design is much better than GainCard. It also showed in my posts on AA. As soon as controversy started it died as well. I made a friend, I think, with Yoshi and 47Labs didn't really blame me for what I did. Yet they incourged me to try different designs and to built someting that would be more original or even better than GC. I took that advice seriously and started thinking.

At that time we were also receiving some feedback from dealers that bought the amps. First thing that was coming up was lack of soundstage depth. The amps sounded OK, presented quite wide soundstage, but the depth was missing. Somebody suggested to use Cardas wire for umbilical, and that improved things a bit. I also wanted to try some other resistors. You know with chip there is not much to tweak, only thing left is swapping for different type of parts. Eventually, I tried Caddock in a feedback loop, and this fixed the lack of depth to a certain degree. The biggest disappointment came up when few people commented that our amp is not as good as 47labs Gaincard (some of them had a chance to try both in their systems). I didn't know what to think. Everything seemed in my design to be better that Gaincard, better chassis, better parts, more attention to detail, yet no desired sound quality.

I had no other choice but to try a non inverted configuration. It happened that at the same time Fedde also tried it, and we posted our results on a forum almost at the same time. Well, we both preferred non inverting amps. After my partner listened to the new amp just for a few minutes, he right away commented that it's better than our previous version, and that we finally achieved what we were always missing: proper soundstage and better dynamics. We started selling those new amps and we received much better feedback. People were actually commenting that they prefered AMP-1 to Gaincard and that it is indeed one of the best amps they have ever heard. The CES proved that too, and we had people coming back for repeated listening and some not believing the sound, those amps produced. We also received most of the orders right after CES ( the orders were not really triggered by both reviews at 6moons).

So this is my amp designer story. Am I amp designer? I don't feel like one. I don't design amps, I design concept, I design the box that plays music. There are many amps out there, but only few that play real music.

What the story comes to, is that I really enjoy what I'm doing now, and finally I found a way of self expression. It's not only the amp building, but also my activity on this forum. Both are a big part of my everyday life.

Up to date we sold approx 50 amps. I don't know if it's much or not, I wish it was more. But none of the amps created negative impression, and especially, after switching to NI config. people are rather enthusistic about them.

None of those amps had a Zobel installed. It is done for a reson, and the reason is that I prefer the sound of the amp without Zobel. Those are mine amps, and I think I should be able to decide about certain design prameters. If we had any complains and cases were amps were oscillating or not behaving properly, we would install Zobel. But we never encountered the need for that circuit.

The design engineers at National are probably not hard core audiophiles. They recommend some circuits just in case, for worst case scenario. But if the amp sounds better without Zobel, why would I like to install it? Is it just to let some guy from a forum to sleep better?