john curl said:
This is the dual mono channels appproach.
And serves as a pseudo 'balance control' as the potentiometers are working independant.
As most CD-players have Digital DAC based Volume attenuator these days,
we can use those two precision dual mono attenuators
to adjust to a suitable output level (max output wanted) & eventual wanted balance correction.
This is the way I would go if designing one preamplifier today.
With modern sound sources, read digital media stored audio,
and todays hi-fi speakers, the balance control, loudness filter + treble and bass has lost much of their job.
We see most true hi-fi amplifiers have no such feature add-ons or have one signal direct switch = tone bypass.
This is good for short and direct audio systems signal paths
with as little impact as possible to The Music.
The music we like so much 😎
Lineup
1audio
I am using fixed bias on all tubes with cathodes earthed and this makes the situation worse. Also some of my cartridges seem imbalanced to me, but as you say there could be other imbalances apart from just gain. Next step for me will be a SS unit with nfb, these op-amp thingys can't be all that bad. 😀
I am using fixed bias on all tubes with cathodes earthed and this makes the situation worse. Also some of my cartridges seem imbalanced to me, but as you say there could be other imbalances apart from just gain. Next step for me will be a SS unit with nfb, these op-amp thingys can't be all that bad. 😀
fredex said:
Cartridges almost always have significant channel imbalance, and some geometric alignment issues as well. You will find that the L/R axises are not at a perfect 90 degrees either. Doug Sax made a test record for checking and optimizing that alignment many years ago. A small missalignment can cause a channel imbalance.
/OT on
Demian, have you considered attending the Burning Amplifier Festival in SF in October? I'm sure many here, including myself, would love to meet you in the flesh. I'm also pretty sure you would enjoy yourself, getting a chance to chat with Nelson Pass and Siegfried Linkwitz?
/OT off
Jan Didden
Demian, have you considered attending the Burning Amplifier Festival in SF in October? I'm sure many here, including myself, would love to meet you in the flesh. I'm also pretty sure you would enjoy yourself, getting a chance to chat with Nelson Pass and Siegfried Linkwitz?
/OT off
Jan Didden
john curl said:Bobken and Hermanv, where have you been hiding? Your solution is, of course, the answer. Now how do we 'remote control' a Shallco switch?
John,
Sorry for the late reply. But your question is ridiculously late. The Ayre K-1 had remote controlled Shallco switches over 12 years ago. (It's still in production.) Our new KX-R has the same basic arrangement. It's done with stepper motors.
Well Charles, I hope you will publish in detail what you did 12 years ago. After all, it is obsolete now, isn't it? Help us all! 
The larger Shallco switch has a detent from hell. I loosened the spring on mine to make it possible to change volume without a pair of vice grips.
With a stepper motor the mechanical detent is redundant, it's quite easy to remove. I didn't try this but I'd guess at significant torque relief. Many steppers are designed to "remember" the last setting after the power is removed. Many steppers have no iron cores.
With a stepper motor the mechanical detent is redundant, it's quite easy to remove. I didn't try this but I'd guess at significant torque relief. Many steppers are designed to "remember" the last setting after the power is removed. Many steppers have no iron cores.
john curl said:Well Charles, I hope you will publish in detail what you did 12 years ago. After all, it is obsolete now, isn't it? Help us all!
John without casting any aspersions or kicking up dust, I just want to point out that you have been less revealing of your circuit details than would be desirable to help all DIYers. However, I fail to understand on what grounds you ask a fellow designer to publish the details of his design?
If only you could appreciate others' requests of you in the same spirit!!
On the contrary, although John hasn't documented things in the manner of an AudioXpress article or a diy construction project, anyone of intermediate skill who followed this and related threads has been given enough info to build a pretty good version of a JC2 or a Blowtorch, if they're willing to put in the effort and money.
Sy; I agree completely, all the relevant core information is provided both in John's posts and his way of replying to others who asked him to comment on their proposed designs.SY said:
I find it somewhat annoying when various people chide others for straying off topic. John has made it fairly clear that he won't publish a detailed schematic or step by step process. It's by asking him questions about minutia that we learn things about the Blowtorch not published directly.
I'm just joking with Charles by putting him in my normal position on this thread. My 'demand' does seem excessive, doesn't it? Well, that is how I feel when I am criticized for pointing out the direction, but not giving exact instructions. Charles and I are colleagues.
PMA said:
Upupa Epops said:
first, PMA,
lower rate college students, those i know,
can not answer you, PMA, about phase response
so, unless those lower rate students are better, you make very wise to do as you intend:
ask the expertise (john curl) on this whatever you want to know
Upupa Epops, pavel dear,
.................................. shame on you 😉
You should always, like us at Lineup Audio Labs,
have a good steady supply of silver teflon caps at home.
I suggest one 100 or 200 pieces buy, right away,
to reduce price/unit to a more normal small business budget level.
*** Please, don't buy from some low quality manufacturer of them caps. We have had serious problems with one package of Silver Teflon Caps.
We had to give them away to some lower rate www.diyaudio.com members. Those that can do with most anything looking like a capacitor.
Seems like they never learn, do they 😀
Mr. Lineup 🙂 Regards & Greetings
Managing Director of Lineup Audio Labs, Inc., Worldwide
Let's be realistic about caps. Caps have both linear and non-linear distortion. Some popular types are actually VERY BAD, yet for years were used without any knowledge or understanding of the mechanisms.
The actual mechanisms were very important in the 1950's and early '60's by analog computer designers. They even found a polystyrene cap a potential problem, and often pushed toward Teflon, when they could. This can be shown in early research papers on DA.
Today, even with polystyrene, polypropylene or Teflon caps, mechanical resonances seem to be very apparent, and 2 papers were presented at the LAST AES on this.
This should all be obvious, but many do not appear to understand or appreciate these defects in performance in what looks to be good quality caps.
Of course, tantalum and most ceramic caps have significant non-linear distortion, as well as DA in the several percent. These should be avoided, if possible. I first published this in an IEEE paper, 30 years ago.
The actual mechanisms were very important in the 1950's and early '60's by analog computer designers. They even found a polystyrene cap a potential problem, and often pushed toward Teflon, when they could. This can be shown in early research papers on DA.
Today, even with polystyrene, polypropylene or Teflon caps, mechanical resonances seem to be very apparent, and 2 papers were presented at the LAST AES on this.
This should all be obvious, but many do not appear to understand or appreciate these defects in performance in what looks to be good quality caps.
Of course, tantalum and most ceramic caps have significant non-linear distortion, as well as DA in the several percent. These should be avoided, if possible. I first published this in an IEEE paper, 30 years ago.
I simply disagree with the view that decomposing a capacitor into ideal linear components to model frequency response abberations (for instance) is a measure of its distortion.
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