John,
In your circumstances I can see you end up with 1k, and that's totally reasonable in that context. You probably wouldn't want to go (much) lower for reasons of class A dissipation in that stage. In my error correction amp I use 5k in a similar stage, that swings 40V peak. But then I add a follower stage to isolate it from the (non-linear) input impedance of the output stage.
I'm still intrigued about the customer demanding you leave out the buffer stage. Is that the end-customer and/or the people that commision your preamp? What's their reasoning? Do they like the 'raw' amp better in their particular system?
BTW Leaving for France for the European Triode Festival in a few hours. Meeting SY, Pete Millett, Guido Tent, Menno vanderVeen etc. We'll be knee-deep in 300B amps this weekend. How's that for a SS afectionado?
My mind is so open, my brain (as much of it as is left) almost falls out jd
Regarding output impedance, it is quite easy to make a serious, rigorous listening test. 50, 100, 300, 1000 ohm output resistors switchable by relays. Then one can make his own decision if there is a difference, and if 1k is fine for him.
Someone mentioned here 1k + 8nF = -3dB/20kHz. Well, this is very soft requirement, probably not based much on experience with real audio.
Someone mentioned here 1k + 8nF = -3dB/20kHz. Well, this is very soft requirement, probably not based much on experience with real audio.
LOL!
Since it obviously needs to be spelled out for you, I was only pointing out just how much capacitance is needed to start rolling off the frequency response in the audio band with a 1k output resistance; not proposing a frequency response "requirement".
Anyone here with some basic understanding of cables would know that a typical interconnect with have nowhere near the 8nF of capacitance required to produce a pole frequency of 20kHz, with any likely HF attenuation being easilly an order of magnitude higher.
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You're welcome. And here is an English lesson for you:
spell out - Idioms - by the Free Dictionary, Thesaurus and Encyclopedia.
Thanks for 'spelling it out' GK. Before we get into some semantics war, this is an 'idiom' meaning: 'make it perfectly clear'. GK is right, it is almost impossible to get SIGNIFICANT frequency rolloff from a 1K source with REASONABLE shielded wire. I'm talking about Radio Shack, Monster, to VDH cable. With the CHEAPER cables I get about 100pf/meter. With the better cables, like one sample of VDH that I like, about 50pf per meter. How long is the connecting cable from your preamp to your amp?
PMA, people should not be EXPECTED to completely understand EVERY word, expression, or idiom, that is not part of their native tongue.
For example, 33 years ago, I gave a lecture to an assembled group at Radio Finland, in Helsinki. I had been living in Europe for 2 1/2 years and had learned speak, what I thought, was a simplified form of English, so that non-native speakers would understand me easily and clearly. After all, my techs, were: Iranian, Swiss and German for at least 2 years.
After my talk, a 'critique' of my lecture was given to me, orally by the gourp. They said I used too many 'idioms' or 'slang' in my presentation. Today, if I had to do the same presentation, I would be even LESS prepared. We native speakers of English see many potential misunderstandings with non-native English speakers, but we try to overlook it, or rephrase it. Sometimes, I even get insulted, and then realize it is just the FORM of the expression, that appeared 'insulting'. Please don't make the same mistake.
For example, 33 years ago, I gave a lecture to an assembled group at Radio Finland, in Helsinki. I had been living in Europe for 2 1/2 years and had learned speak, what I thought, was a simplified form of English, so that non-native speakers would understand me easily and clearly. After all, my techs, were: Iranian, Swiss and German for at least 2 years.
After my talk, a 'critique' of my lecture was given to me, orally by the gourp. They said I used too many 'idioms' or 'slang' in my presentation. Today, if I had to do the same presentation, I would be even LESS prepared. We native speakers of English see many potential misunderstandings with non-native English speakers, but we try to overlook it, or rephrase it. Sometimes, I even get insulted, and then realize it is just the FORM of the expression, that appeared 'insulting'. Please don't make the same mistake.
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(and on BMW's engineering requiring super fuel)
My BMW wants Diesel and it ran 255 Km/h IAS last week on an empty Autobahn.
It's supposed to limit electronically at true 250 Km/h, but I didn't dare to try
even faster. And usually, I'm below 8 liters/100 km (not in town).
On low octane fuel, you get worse results than on high octane, the Carnot
process requires this, and contemporary engines adjust for the fuel quality anyway.
More compression is more efficiency and with high octane you can get more, but Diesel wins here.
To be not too far off topic, Meat Loaf's "Bat Out Of Hell" sounded nicely to
this, even from a MP3 CD. OK. I might replace some audio cables.
Gerhard
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Getting rid of components is something that I can understand, there is real beauty in simple solutions.
Unfair?
Maybe other amps go into the same category?
If the KX-R by CH was a DIY thing would it be mentioned at all in magazines?
Cheers
What is your point Stinius? The REASON for me saying anything about magazine ratings is that all 'A' products have to be reviewed by the magazine. The CTC does NOT qualify to be reviewed, so it was never 'rated' by 'Stereophile'. Now, if in the opinion of the designers and other owners of BOTH the CTC BLOWTORCH and the Parasound JC-2 preamp (which has an 'A' rating), that the CTC is a BETTER sounding preamp, would that make the 1K output resistance less of a potential problem than has been worried about on this thread?
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