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Old 11th December 2018, 04:39 AM   #21
sumotan is offline sumotan  Indonesia
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Isn’t it like food Anetech everyones got different taste buds. You may be able to pic the best caps with your Lcr meter but that does not mean that it will sound gd to another persons ears. If the circuit is design from ground up, what you say holds true to a certain extend & even if it is very very well design it does not mean that one cannot improve sound further by careful selection & placement of passive components.
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Old 11th December 2018, 05:09 AM   #22
anatech is offline anatech  Canada
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Hi sumotan,
Quote:
Isnít it like food Anetech everyones got different taste buds.
Well, over 30 years experience and my customers would strongly disagree with you and the voodoo you seem to be pushing.

In long experience, the lower distortion results were always prefered by customers. I guess if the equipment you are working on isn't very good, then adding a flavour to the sound quality might be an amusing distraction. But in no way is that good audio at all.

Case in point. I just rebuilt a Marantz 7 (a real one). Starting out the distortion measured over 1% at 2 volts out. After the rebuild replacing both resistors and capacitors, the distortion measured 0.0055%. A massive improvement. The customer called tonight actually, and he was annoyed that music from crappy sources sounded worse, but when pressed he admitted that good music sources and masters sounded a lot better. So when I asked him what he wanted done, he said he'll try to make up his mind. Previously the preamp hid all the defects because it really manged the sound going through it hiding the poor quality. However with the highs restored , the older music (1950's through mid 70's) couldn't hide behind equipment any more.

So, the rebuilt preamplifier now shows the truth instead of glossing over the bad bits. He listens to good quality music normally. I'm pretty confident he will choose the cleaner version of that preamp.

So you see, introducing distortion and noise might satisfy someone short term, or until they hear something really good compared to their current stuff. But reducing distortion and noise floor is always the right direction. The better capacitors do not have a sound (or minimal at best).

One further comment folks. Capacitor ESR is not the parameter that matters in the audio path. It is entirely pointless to make decisions on ESR except in maybe filter capacitors. What the most important thing to look for is called dielectric absorption. What that is is energy lost in the dielectric of the capacitor (= distortion, or having a voice for example). Unfortunately, good meters that do an accurate job of measuring dielectric absorption (or DA) are more expensive than the cheap meters that measure series resistance. So there is a cost to admission to that party. But wouldn't you rather be right than being hit and miss by chance?

Also, if someone is charging me to work on my equipment, I expect them to have the proper instruments to support what they are charging me for. Guesswork doesn't cut it these days. The better the equipment sounds, the more people will make the choice to listen to it. When you are dealing with cheap, "junky" electronics (example NAD 3020), all bets are off. But it would seem to be intelligent to take the path of improved performance (lower distortion and noise) than trying to colour the sound, maybe to hide the problems?

Here is the tests for the right channel of that preamp I was talking about. Tell me which one you would rather hear your music through!
Attached Images
File Type: jpg R THD as found 2Vrms.jpg (142.9 KB, 168 views)
File Type: jpg R THD after upgrade 2Vrms.jpg (142.4 KB, 119 views)
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Old 11th December 2018, 05:18 AM   #23
sumotan is offline sumotan  Indonesia
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Hey Anatech
I thought you mention to keep an open mind. I don’t practice or try to push Voodoo ya
Im just sharing my findings & I don’t charge anyone for my services. So pls let’s not argue due to difference of opinion. It’s just too bad that we’re too far apart for not I’ll invite you over to have a listen on my set up & you be the judge.

Cheers
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Old 11th December 2018, 05:41 AM   #24
anatech is offline anatech  Canada
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Hi sumotan,
Quote:
I thought you mention to keep an open mind.
I completely agree with keeping an open mind - except when there is overwhelming proof that shows something is true. Can you imagine science, or even a court of law if they ignored certain proof and entertained any and all theories? What a mess! When there is proof, and instead of providing just my word, I attached proof as well.

Human beings are not test instruments and are not calibrated at all. Our references drift, so you can't trust your opinion on how something sounds (within reason). With informed training assisted with test equipment you can settle in on a reference that you can compare to. Humans are reasonably good at comparing things, but they still need some training to recognise accurate sound reproduction. A really good reference system really helps as well. You will find that really good sounding systems also measure well. When the quality isn't high, you can get away with murder!

Everyone here is trying to put in the best effort they can. So pointing people in the right direction is important. Charging for your opinion or not isn't important here. What is important is to be correct, because there are hundreds of people who will read what is offered up as information. Most people reading this never post, but "you" have na effect on them just the same. "you" means everyone who posts in any thread. Isn't that a sobering thought?

Many service people read what is on the internet and simply implement what they read and pass that off as their knowledge. I've seen several pieces of equipment serviced exactly as some article or report spells out. People are being charged for the information given from every corner of the internet. Paint by numbers with no understanding of what they are doing. At least help them get it right.

-Chris
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Old 11th December 2018, 06:52 AM   #25
johnego is offline johnego  Indonesia
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Quote:
Originally Posted by anatech View Post
Here is the tests for the right channel of that preamp I was talking about. Tell me which one you would rather hear your music through!
May be the one on the left? On the left the distortion is very high but low order. On the right the distortion is much lower. I'm not saying that I like low order harmonics, I prefer lower distortion, but the two charts cannot tell the quality of the amp. Often, the lower distortion one sounds wrong, not because it is low distortion but because the designer tried too hard to lower the distortion, thinking that it is all that matter.

I had a Marantz 7. With the original design, at least it is euphonic. With whatever modification, I have no idea why the amp could sound good?
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Old 11th December 2018, 07:15 AM   #26
anatech is offline anatech  Canada
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Hi John,
Sure, here is the left channel. I have IMD as well, they tell a similar story.

The rebuild included new tubes (Electroharmonix 12AX7EH) and replacement of the resistors and capacitors. The selenium rectifiers were replaced with silicon types. The main filter capacitors were surprisingly in good condition. I check the waveform across them under load with an oscilloscope. No leading edge "pips".

There was no change in schematic. It's a classic preamplifier that was well designed. I'm not going to second guess those excellent engineers. Therefore, if the same work was done to your 7, it would turn out the same way. It sounds much better now, but not as euphonic. That character is due to the carbon composition resistors. Terrible things.

I used to repair equipment with carbon composition because that was all that was available. 5% was considered high precision. 2% was just silly and we didn't ever see 1% resistors. We used to match resistors by cutting a notch into the side of the low value one and cut until the resistances were equal. Then seal it with a lacquer. Pretty barbaric, but that was what we were taught.
Attached Images
File Type: jpg L THD as found 2Vrms.jpg (145.3 KB, 181 views)
File Type: jpg L THD after upgrade 2Vrms.jpg (146.0 KB, 177 views)
File Type: jpg L IMD as found 2Vrms.jpg (146.8 KB, 169 views)
File Type: jpg L IMD after upgrade 2Vrms.jpg (145.9 KB, 167 views)
File Type: jpg R IMD as found 2Vrms.jpg (147.3 KB, 166 views)
File Type: jpg R IMD after upgrade 2Vrms.jpg (144.3 KB, 20 views)
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Old 11th December 2018, 07:22 AM   #27
anatech is offline anatech  Canada
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Hi John,
Any good designer knows you can only optimize one trait at the expense of others in the design phase. When I design something audio, I listen and measure. Things have to pass both tests and good designs generally converge together. I have never met a good designer who doesn't listen to their work , and measure it.

It's a myth that designers design only with measurements. Actually, the reverse is more common where you have someone with some knowledge that "designs by ear". They typically don't have test equipment, or it's really old and next to useless. My own experience has shown that products designed by ear typically don't sound as good as they could, and have redesigned many pieces where the sound quality and performance was greatly enhanced. A good example of this would be Counterpoint equipment.

-Chris
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Old 11th December 2018, 07:43 AM   #28
sumotan is offline sumotan  Indonesia
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Well Anatech the way that youíve put it is like Im misguiding Pashka.
If you read again I actually advice him to just change the internal speaker wires to test.
We all have different opinions or methods to achieve objectives. Me Im just sharing what Iíve learn & discovered. Like most of us here, itís up to the individual to test, learn & judge from their findings as well. We should leave our differences in opinion as is. The beauty of diy in itself is a journey of discovery be it done technically correct or not , success or failure one still learns from it.
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Old 11th December 2018, 08:00 AM   #29
johnego is offline johnego  Indonesia
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Quote:
Originally Posted by anatech View Post
The rebuild included new tubes (Electroharmonix 12AX7EH) and replacement of the resistors and capacitors. The selenium rectifiers were replaced with silicon types. The main filter capacitors were surprisingly in good condition. I check the waveform across them under load with an oscilloscope. No leading edge "pips".

There was no change in schematic. It's a classic preamplifier that was well designed. I'm not going to second guess those excellent engineers. Therefore, if the same work was done to your 7, it would turn out the same way. It sounds much better now, but not as euphonic. That character is due to the carbon composition resistors. Terrible things.
Hi Chris,

Mine was using GE tubes. Resistors are carbon but the old Riken (gold plated one). I still have the complete module (along with the R-core transformer) but I have a prejudice of what it possibly can deliver, so I'm not motivated, or may be when I have to sell the stuff (no schematic modif, you said?). Apple to an apple (and low distortion too), how do you compare it with the octal Aikido? I have a feeling that you're not a tube guy so I think it is not up to your standard. May be you are an opamp guy? I have some AD797BRZ which should be able to deliver better measurement than any 12AX7!
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Old 11th December 2018, 10:36 AM   #30
carlmart is offline carlmart  Brazil
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Why would a 20000uF power supply capacitor kill the sound when it's used just for the LF stage? It certainly will not.

But now I had another look at your schematic, and it's a single supply design, with an electrolytic capacitor at the output. Is that the one you want to change to 22000uF?

It's different then.

Another thing it's using separate transformers and supplies for HF-MF-LF. Are the transformers voltages different?

I completely agree with Anatech on his comments.

To start with you have to have extremely good speakers to spot differences when you change such things as internal/external cabling, as long as all are good quality.

It's also true that sometimes you can't measure things you repeatedly hear. But that happens less and less nowadays. Good instruments are very expensive too.

If you really want to play with things, first of all you should train your ear and your listening. I have been a professional location and studio film/TV recordist for many many years, and I did have to train my ear. This is very important, and ANYONE can do. Focusing is the key to this.

You need to find non-electronic music, usually classical and with few instruments. Then you can focus and identify each instrument, paying attention to how it separates or integrates with the other instruments. Do that with every instrument, and then to the whole.

With time you will forget about that, but your ear will separate things automatically.

With parts changes, the key thing is not to "expect" a change. This is a very common mistake, IMHO, simple as it seems. Because then your mind may "imagine" there is a change. This is probably the hardest thing to do. But anyone can do it.

This is just an advice, not a teaching.
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