hitsware said:
Don't know.
There may be some beeswax in it. My friend tells me it's a blend of waxes and has a very low dielectric constant. I could probably talk him into giving me his SSN, bank account, credit card and PIN numbers, but I haven't been able to get him to give me any more details on the wax.
He gave me a five pound block of it so I have plenty to play with for now.
se
john curl said:
I am with you on this one, John C.
Besides, I wouldnt even consider a coil in my pre amplifier signal chain.
A capacitior input/output is bad enough, isn't it?
I am now refering to a hifi state-of-art amplifier here. On Topic.
The Blowtorch no compromise design by john curl + his audio friends.
No offense, Steve Eddy.
I actually like you very much. As your 100% openess & honesty. More than you ever will know.
Probably I prefer your attitude before John's / PMA-s' at times ...
I have learned some very good things from reading your posts, man.
Keep your own topic going, professor John Curl.
I know you post with a smile on your old kind of lips.
Even when thrownig plenty of woods onto our Fire of controverse
Some are opportunists. Floats with the prevailing streams.
No names mentioned. Even though in my mind very present.
Other are challengers. Challenge our minds with controversial questions put.
Without any whatever compromising with their own long time earned knowledge.
Lineup, July 2008.
For some reason, the PASSIVE coil at the end of the amplifier makes a bigger difference that would be implied by static measurement, especially measurement with a resistive load. I have heard the difference, and so do at least 4 other internationally famous noted audio designers, some of whom are on this website with me.
Re: Re: Re: Re: Re: Re: Re: RFI
There is nothing sacred about 100 pF. However, as the first line of defense against VHF ingress, it is probably sufficient, while it is unlikely to cause any HF rolloff to even high-impedance sources.
Cheers,
Bob
myhrrhleine said:
Would there be a reason for 100p?
Why not 220p, 330p, or even 1000p while we're at it?
Thanks for the input (termination)
There is nothing sacred about 100 pF. However, as the first line of defense against VHF ingress, it is probably sufficient, while it is unlikely to cause any HF rolloff to even high-impedance sources.
Cheers,
Bob
john curl said:
John,
You would like us to think you did something very special in circuit design to wean yourself off of it, but so far as I can tell you have merely decided that the risk of not using any coil at all is acceptable.
If I am missing something circuit-wise that you have done that specifically allows you to not have the coil, please bring that to my attention and let us know what other compromises it may involve.
Cheers,
Bob
Bob, it would be pointless to add a coil, when the wiring itself adds enough inductance. I agree, and already stated ON THIS WEBSITE, that .5uH is probably OK, but I don't want to add anything that I don't need, and so far, I don't need it. Parasound, sometimes adds a coil to their cheaper, commercial products. IF the same manufacturer thought that a coil was necessary on my designs, they would insist on adding it. IF you can prove to me that adding a coil to a JC-1 would add a significant degree of protection, I would change the design, but I have made coils, have a drawer full of coils that I made for power amps, have calculated and measured the inductance of my coils, for decades. NOW, I don't need them anymore. What is the problem? We call it progress, where I come from.
What do people really want to talk about on this thread? Preamp theory, design, how to? They are really separate, and really require a different approach for each. Many here can build an 'acceptable' preamp or power amp. It, like a normal auto, will 'get you down the road'. Of course, it would be cheaper and easier just to buy something used, and fix it up a little, rather than make something from scratch.
It seems to me that you should want to make something extra special, that really is better than average or typical. That is the real problem. What is 'extra special'? Is it extra low distortion, extra wide bandwidth, what?
Some designers over the decades have consistently found that some factors make an amplifier or a preamplifier better than what you can buy at a reasonable price. We try to inform people here what these 'factors' are, just to pass along the information. I hope that you can understand how frustrating it can be to have people with less experience, rebuke you at almost every turn, when you are only trying to give some info away. This has certainly gotten me to contribute less, but if others have an equal or even a better input, I would like to hear about it.
It seems to me that you should want to make something extra special, that really is better than average or typical. That is the real problem. What is 'extra special'? Is it extra low distortion, extra wide bandwidth, what?
Some designers over the decades have consistently found that some factors make an amplifier or a preamplifier better than what you can buy at a reasonable price. We try to inform people here what these 'factors' are, just to pass along the information. I hope that you can understand how frustrating it can be to have people with less experience, rebuke you at almost every turn, when you are only trying to give some info away. This has certainly gotten me to contribute less, but if others have an equal or even a better input, I would like to hear about it.
It might be that with the newer, higher FT transistors you can get away with a bit more capacitance on the output. My reasoning is that if you set the amp GBW to a typical 2MHz, the output stage pole using these new devices is way beyond this - unlike the old days (eg 21193/5 vs 1302 and its complement which I jus t forgot).
Another trick is to 'slug' the amplifier which is to say run with a dominant pole at a very low frequency, like Doug Self's blamless. On top of this, we can reduce the overall loop gain at the expense of distortion.
However, I think the latter two approaches are somewhat of a compromise and really do not allow us to exploit the progress made by the semiconductor guys who have brought us these great new output devices. Thats real progress I would not want to miss out on.
I am sure a few uH on an output coil won't kill the sound - there are too many 'A' rated amps that still use them and no doubt their designers will continue to use them in the future.
Another trick is to 'slug' the amplifier which is to say run with a dominant pole at a very low frequency, like Doug Self's blamless. On top of this, we can reduce the overall loop gain at the expense of distortion.
However, I think the latter two approaches are somewhat of a compromise and really do not allow us to exploit the progress made by the semiconductor guys who have brought us these great new output devices. Thats real progress I would not want to miss out on.
I am sure a few uH on an output coil won't kill the sound - there are too many 'A' rated amps that still use them and no doubt their designers will continue to use them in the future.
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