John Curl's Blowtorch preamplifier part II

[Nelson Pass]

Originally Posted by syn08

It is possible, by using an (e.g.) Clearaudio Statement Reference ($150,000), to get some significant results.

I would suggest the Basis "Work of Art" turntable, which will
leave you enough left over for a car.

[john curl]

Pretty difficult to believe.

[Joshua_G]

Originally Posted by syn08

However, nobody can persuade me to believe that such differences are audible in my system, where measurements are buried in random errors.

How about actual listening, instead of waiting for persuasion?

[anatech]

Hi Andre,

I believe most here will regard good cables as those that have the least influence on a signal. The problem is cables, or any equipment for that matter, can influence certain aspects in sound that are not easy or possible to measure.

Right there you have zeroed in on why many designers who have technical knowledge don't seem to hear a difference. They pre-qualify which cables to compare, since it doesn't make any sense at all to compare a cable ill-suited for the task. Not only that, but I'll bet they make their cables only as long as they need to be. You may require longer cables of a couple meters in order to show differences.

I like using Canare wire personally. It has the added advantage of being very flexible.

Do you have any suggestions which cables to use that doesn't "damage" the signal? I would be certainly be glad to finally find a perfect cable.

I'm sure you'll agree it is simply a matter of using a cable assembly that affects the signal the least - while keeping prices within the realm of reality.

-Chris

[syn08]

Originally Posted by Joshua_G

How about actual listening, instead of waiting for persuasion?

How about...

[syn08]

Originally Posted by SY

Hagerman Technology LLC: Cartridge Loading

syn: Interesting sims supporting what I've seen.

Thanks SY, I am aware of these resonances. They ocur mostly for MM and perhaps for high output MCs. The Benz Micro Wood SL that I am currently using has very high resonances (only a few uH inductance).

The problem was the inability to reproduce any frequency response within 0.1dB. Obviously, no resonances were encountered up to 100KHz.

[Curly Woods]

Originally Posted by syn08

Thanks SY, I am aware of these resonances. They ocur mostly for MM and perhaps for high output MCs. The Benz Micro Wood SL that I am currently using has very high resonances (only a few uH inductance).

The problem was the inability to reproduce any frequency response within 0.1dB. Obviously, no resonances were encountered up to 100KHz.

syn08,

So your position is that resistive loading of a MC is inaudible?

[anatech]

Hi Joshua,

Sometimes there are some correlation between how an amp is measured and how it sounds, but most of the time there isn't such a correlation, at least not a direct and obvious one.

This is going to depend a great deal as to the resources one can bring to bear on the test. As I recall, you had said that for most, if not all of your career, you had to get by with minimal equipment and supplies. Your ability to measure would therefore be considerably limited compared to most good audio service centers I have seen. That makes your comment true and accurate for your situation. Certainly, more well equipped technicians would have the ability to "see more". Moreover, some people can look at a schematic, see the construction and have a pretty good idea what an amp may sound like. Not every time, but certainly noticeable and better than guessing. Even I can do this occasionally. I'm sure that a person such as John (Curl) with his experience also has this skill. I'll extend that list of people to most who design amplifiers and post here.

One thing is that the human ear (actually, the ear-brain-mind mechanism) usually doesn't notice harmonic distortion of 0.5% or less in the second harmonic and 0.2% or less in the third harmonic, while it is more sensitive to the higher harmonics and extremely sensitive to the 7th harmonic.

That really depends on signals, coupled with the transducers used and how quiet the listening area is. Like everything, there is a fair range on these numbers.

While it is very true that the higher harmonics do seem to be picked up more easily than low order harmonics, singling out the 7th might be too optimistic. Yeah, I know John likes to look at this number, but you can't isolate one harmonic. You must look at all of them. You'll generally find that the absolute level of the 7th harmonic is related to all of them in the series. They all vary as each other in the higher harmonics. Looking at several spectrum "pictures", it can be seen that the 7th may be of a higher amplitude than it's neighbors, but you also have to look at the actually frequencies of these harmonics. For instance, if someone can hear to about 16 KHz, the 7th harmonic is only important to about 2.3 KHz for that person. For a claimed normal of 20 KHz in a younger child / teenager, you can move that up to about 2,860 Hz. The ability to hear problems diminishes rapidly after that, especially since these harmonics are very low in level.

Zeroing in on one specific factor (like the 7th harmonic) posses a very real risk of missing the more important measurements. You need to look at the entire picture in order to come to a valid answer. Note: John, I am in no way "attacking" your interest in the 7th harmonic. I am specifically answering Joshua's post. I am more than certain you know what and how to measure audio equipment.

So, when one amp measures 0.8% THD and another one measures 0.001% THD, by those numbers alone it's impossible to tell which one of them will sound better.

Well, of course! Those numbers in isolation have reduced relevance. I will bet that the amp measuring 80 X less THD has had some care in it's design. That's assuming you don't do something silly like compare a tube amp to a solid state amp on THD specs alone. Now that is a pretty meaningless exercise if you ask me!

Another thing is that the measurements which are probably most correlated to the way an amp sounds, that is, TIM and its derivates, are seldom taken and almost never published.

Two reasons for that. You will only see things published that the marketing guys want you to see. Also, as you multiply the specs you want to publish, you become responsible for more acceptance testing in production. Plus, you also force all your service depots to both buy more test equipment (and more expensive types) and spend more time testing to verify service which will all be passed on to the end user. Always remember that the end user pays for everything - including losses. If they don't, the business in question is out of business.

All in all, there is no way to tell how any amp sounds by looking at its' published measurements alone. So, only listening tests can tell how any amp, or any other piece of audio gear, sounds.

Well, again it depends on the technology used in the amplifier, and what specifications you are looking at. However, some specs can give you an idea on sound quality, along with the brand name (that's part of the spec too). Specifications are not useless and are most often used to determine if the product is in fact operating within normal specifications. So these are highly beneficial to the end user in supporting any claims that the equipment is substandard. Most defects will affect the measured performance.

The impressions of various individuals of the same audio gear and their evaluations of it are varying to enormous degree. For some a certain audio set sounds great, while to others it sounds mediocre, or bad. If it weren’t like this, all would buy the same amps, speakers and other pieces of audio gear.

Exactly my point. How much has to do with the effects of advertising, brand expectations and price point? Add to this, possible interactions with the loudspeakers? Often, any amplifier that can drive the silliest speaker loads are well regarded, and for no other reason than that. Ohm speakers and several others come to mind that have very low impedances at some frequencies at least. Infinity produced some evil designs that became popular for this reason alone.

Therefore, when I consider purchasing any produced piece of gear for my audio set, whenever it's possible, I listen to it before purchasing, preferably on my own setup.

That's more than fair, and acceptable at the higher price points. Not doable for mass market types.

In such cases, I have to rely upon testimonies, or reports of others. Now comes a major question for me: which testimonies or report should I note and which ones should I ignore? As a rule, I don't read reports of audio magazines, whether published, or on-line, for I'm suspicious of possible commercial interests. So I'm left with testimonies and reports of fellow audiophiles. However, there is still the question: which testimonies or report should I note and which ones should I ignore? This question is so much relevant in the light of the enormous differences in appreciations of the same gear. From experience I know that my friends who hear differences between different well engineered cables and me have very similar appreciations of audio gear, while others who don't hear such differences between cables have markedly different appreciations.

Self fulfilling prophesy now.
In truth, you should listen to all well designed, well made equipment in your price range. For example, Nelson Pass has designed commercially successful equipment that are different in the most fundamental ways. To do anything else is simply to restrict your choices, but then that is your problem.
For example, I've had poor luck with every single Ford I have ever bought. I've had three now, and each was a disaster in it's own little way. All suffering from poor quality. However, I'll still at least look at them and test drive. You know what their slogan is? Have you driven a Ford, lately? They say this about every 8 years and haven't really changed.

Therefore, I'd not consider trying any non-produced design by a designer who confesses that he doesn't hear differences between cables. This is because it's an indication to me that probably his appreciation of the sound of audio gear and mine are most probably markedly different. Of course, not all who claim to hear differences between cables actually hear them. However, I do need a starting point.

Self fulfilling prophesy now.
See above.

I'm absolutely convinced that a designer should have refined listening in order to design and produce great sounding audio gear.

All he needs are good people on staff to listen. The designer could be deaf for all I care. It's a non-issue. Believe me when I say that if his stuff doesn't sound good, it doesn't sell. Change or die.

As for MC phone cartridges, many times their recommended load is published.

That whole idea is really odd coming from you. Start at the recommended loading and experiment from there. If you can't determine what the best load is, put it to the published "happy spot".

I use E.A.R. MC4 Step-Up transformer who has inputs which are marked as 3, 6, 12 and 40 Ohm.

You really have to know that transformers for this are going to be more than just a little problematic. Loads are reflected both ways with the transformer's character thrown in for good measure. You can't divorce the input circuit of the preamp from the transformer settings at all. Have fun with that! But I guess as long as you like the sound you're getting, mission accomplished.

-Chris

[john curl]

I was told of another definition of PhD, it is 'Piled higher and Deeper' ;-)

[Curly Woods]

Originally Posted by john curl

I was told of another definition of PhD, it is 'Piled higher and Deeper' ;-)

LOL!!! I owe you a beer John