You reminded me of my transition product the AD524 started out old school but we transitioned to the Applicon system (take a lunch break to redraw the layout). One of the principles in Applicon was two doors down in my dorm, made everyone listen to No Fun back in the day.
Sorry Hans, but my speaker cones flap in and out at about 0.5Hz. I can see it.
Wow, you were advanced, we used to draw layouts by the mask, using pen on mylar, then a tech was manually digitizing the mylar in a Varian 620L 16bit computer with 32kb of ferrite core memory. After correcting the digitizing usual crap result on a B/W graphics 14" terminal, a paper color plot followed, visual peer verified, then a mag tape was generated and off to the ruby plotter/cutter. When a VAX-11/780 was installed, (with 300Mb hard drives, and interactive graphics), that was heaven. Nevertheless, the first designs on the new system were a disaster 😀.
The Fall was the official band at the time, a Mark Smith photo was glued on my terminal 😀. He passed last year way, way too early...
P.S. New Pere Ubu double CD is out, got it last week, David Thomas is very much alive and kicking ***, the live half @Montreuil is amazing 😀.
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Sorry didn't realise that it was a competition to get maximum attenuation for minimum BOM cost. My miniDSP can do 8th order roll off if I just want to hammer LF. But I don't. I'm interested in if there is a better way. There may be, there may not but it's worth investigating as I can prototype filters on the laptop quickly. But the ins and outs are for another thread.
This is exactly what I would expect.
One rev at 33 1/3 rpm is exactly 1.8 seconds. This is 0,555 Hz. This happens if the vinyl has one warp - if it has more
I have a large collection of old vinyl and only a very few have warps that are bad. The majority is still flat after 40 years or have only mild warps than can easily be flattened out by a simple record clamp on the TT.
Furthermore, spending significant money and effort for a decent TT, a precious MC cart ... who is then only playing bad records??
"The Fall was the official band at the time, a Mark Smith photo was glued on my terminal . He passed last year way, way too early... "
Founding member (1976-1977) Tony Friel worked in my team at Philips as an engineer in the late 1990's early 2000's. Nice guy. When I told my 15 year old at the time he couldn't believe it.
Here's a link to his web page:- atomicsoup.co.uk - web site of Tony Friel
Check his CV out - mentions the Philips connection.
Founding member (1976-1977) Tony Friel worked in my team at Philips as an engineer in the late 1990's early 2000's. Nice guy. When I told my 15 year old at the time he couldn't believe it.
Here's a link to his web page:- atomicsoup.co.uk - web site of Tony Friel
Check his CV out - mentions the Philips connection.
Actually it took me only 1 op amp to implement a 3rd order, 60dB/decade, high pass filter with negligible (0.1dB) impact at 20Hz. More steeper than that, and mr. Tomlison my kick you in the butt for exceeding his group delay limit (one of those FUD limits, fun to follow).
This is exactly what I would expect.
One rev at 33 1/3 rpm is exactly 1.8 seconds. This is 0,555 Hz. This happens if the vinyl has one warp - if it has moreit must have undergone a serious mistreatment.
I have a large collection of old vinyl and only a very few have warps that are bad. The majority is still flat after 40 years or have only mild warps than can easily be flattened out by a simple record clamp on the TT.
Furthermore, spending significant money and effort for a decent TT, a precious MC cart ... who is then only playing bad records??
Most of my records are ok - but I have a few that flap the cones a bit unfortunately 🙂
I think TH shows a graphic in one of his papers on the detectable limits of GD from a DIN standard- the graph axis is mislabelled as 25 seconds - I presume they meant 25ms. But some of the filters I've simmed are at 5ms at LF (IIRC) - unlikely that it will be audible.
Call me a wierdo, but I still want an elliptic eq for LF. The LP is blended to mono anyway so any vertical signal below 150Hz is likely to be artifact.
Given the current limitations in my listening space a little bit of group delay is the very least of my worries 🙂
What you just described could best be characterised as a learning curve, where everybody has the right to learn from his faults.
Instead of frequently chopping heads and getting sick, a bit of politeness makes a discussion a lot less aggressive. 😀
Hans
Problem is, some never realize they are on a learning curve, and end up forever in the simulation realm.
As of chopping heads and discussion tone, that's in the eye of the beholder. You are, as far as I can tell, a mostly simulation only expert, irritated by anything that goes beyond your LTSpice computer screen, and using your simulator for clubbing everything. That, without any further attempt to interpret the simulation results and understand the underlying causalities, while "this is what simulation says" and "why don't you simulate it" are the absolute arguments. You are not the only one here, the Homo Simulantis species is spreading like a disease. There, you asked for it 😀.
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AFAIK, Mr. Tomlinson didn't publish any data to support his 20mS group delay claim. No data is FUD in my book.
The 3rd order Salen-Key infrasonic filter I did covers very well the cone flapping due to warpage. Actually, the reason for building such an infrasonic filter was not so much warpage, but the very low frequency (<0.1Hz) popcorn like noise in single ended very high gain (75-80dB) DC coupled amplifiers. These fluctuation (of likely thermal origin) don't get to the speaker, but can saturate any (near) DC coupled stages, before the power amp.
For the Homo Simulantis around, try to simulate these thermal fluctuations. Wait, they must not exist 😀.
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Perhaps if you engage your brain and not your mouth for a second and dial the never ending stream of tiresome invective and self-promotion down a notch or two, you may find the time look at figure 7 in the link attachment.
http://hifisonix.com/wordpress/wp-c...phic_Preamplifiers_Holman_Audio_July_1977.pdf
Yes, self promoting. Unlike yours, my sales are slumping and I need a boost 😀.
Thanks. No data (or justification) on the 20mS group delay audibility threshold, the standards are hugely over this value, even at 50Hz. Next simulation, please 😀.
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I can send you some HPS versions for free (I have them all since 1.0), but you are not going to like the shipping fees. About the common base boards in this thread, give me a couple of weeks and I'll send you a couple (for stereo) of the new fully assembled boards for free, i'm afraid I already butchered the old version boards. They'd fit in a padded envelope, no problem with shipping.
T. Holman didn't actually compulse about the variance of group delays with frequency; instead, he simply showed that the sum of a properly placed resonance and a third order (IIRC he used a Butterworth for both the Advent receiver and the Apt preamp) filter was somewhere sufficiently less than contemporary standards.
All good fortune,
Chris
All good fortune,
Chris