• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Townsend Isolda cable

Status
Not open for further replies.

jsrtheta

Addicted to Fun and Learning
Joined
May 20, 2018
Messages
936
Likes
991
Location
Colorado
Well, here you go gentlemen, I dug out the images from 2016.

View attachment 24200

The purple and red is before I tweaked the balance control to balance the channels. The green and white is a best case 'flat' frequency response of the integrated amplifier at (1W/1KHz/8ohm (2.83V) preset before sweep). Eeek! -13.5dB at 20Hz and -3dB @20KHz It was so bad I ran a loop-back to make sure my gear wasn't broken.

Was it the preamplifier or the power amplifier or both? I investigated this further by feeding direct into the power stage internally and got this (1W/1KHz/8ohm (2.83V) preset before sweep):

View attachment 24203

Around -3.5dB @20Hz and -0.7dB @20KHz- slightly better. So, it was a combination of the preamp stage and power amp stage. Basically it tested and sounded like a PA amplifier (Murray also made PA amplifiers under the Auditec brand). It does have a 'softness' control which when activated gave the response below, not unlike a typical loudness, except it is not linked to volume position. It does however, make the amplifier partially listenable.

View attachment 24205

These are screenshots from my trusty old AudioLab hardware.

Murray's basic construction and component quality was excellent for the mid 70s era. A few glaring mistakes in design, but I didn't reverse-engineer the unit to work out where all the issues lay as it was bought just a curiosity and designed by a 'legendary' Australian. Judicious use of the tone controls could partially flatten the response, but the extreme adjustments required to do so were ridiculous. I was tempted to unscrew the knob screws and re-position the zero point, but just left it, as it really wasn't flat in any case.

Man, them are butt ugly!
 

pozz

Слава Україні
Forum Donor
Editor
Joined
May 21, 2019
Messages
4,036
Likes
6,827
At the risk of embarrassing myself to the world, I have used Max's Isolda speaker cables for some years. I've compared them to various other speaker cables of conventional construction. I prefer these cables. To me there is an audible benefit from cables of this flat construction (I've used three different such designs over the years but I prefer these). The difference of the construction is mainly heard in lock of the sound stage - Max's add apparent extension at both ends- including tightness in the bass that helps things lock together. I doubt the virtues would be noticeable without nearfield listening and a low output impedance (SS) amp or suitable speakers (low extension). Sort of "lowish" impedance amps don't do it for me (eg d'Agostino, very doubtful about any valve amp). Over many years I've often wondered what the cause is but, whatever, I like them. I'm not closed about this and have listened to many speaker cables at all price ranges. Sorry to all the nay sayers here - you do need to listen too - not just assume. So please measure, but please listen too.

My background btw is 38 years in power electronics design. Sometimes I think "suspension of disbelief" needs to relate more to my technical views rather than the musical event portrayed.

Presently enjoying Nord n-cores driving B&W 800D3 from DEQX /Roon.

M
Would you mind sending your Isolda cables to @amirm for testing?
 

restorer-john

Grand Contributor
Joined
Mar 1, 2018
Messages
12,586
Likes
38,285
Location
Gold Coast, Queensland, Australia
what I really want to know is: what is the actual Dutch saying?

1605829441632.png


1605829548803.png
 

StefaanE

Addicted to Fun and Learning
Forum Donor
Joined
May 12, 2020
Messages
528
Likes
929
Location
Harlange, Luxembourg
A fascinating thread. Yet given everything I've read what I really want to know is: what is the actual Dutch saying?
Fascinating indeed, and sorely lacking an ending. Anyway, the Dutch version is "maak dat de kat wijs", and it's used to indicate something is utterly unbelievable. One can have great fun (provided one knows both languages) substituting similarly sounding English words in Dutch sayings.
 

restorer-john

Grand Contributor
Joined
Mar 1, 2018
Messages
12,586
Likes
38,285
Location
Gold Coast, Queensland, Australia

BDWoody

Chief Cat Herder
Moderator
Forum Donor
Joined
Jan 9, 2019
Messages
6,949
Likes
22,627
Location
Mid-Atlantic, USA. (Maryland)
Hi Folks, Just wanted to revisit this thread with my latest findings: "The Sound Of Music and Errors in Speaker Cables"

https://mcusercontent.com/37242be22...Music_and_Error_in_Your_Speaker_Cables_1_.pdf

Do you have any controlled listening test results that can demonstrate this is an issue that anyone on this planet needs to be concerned with?

I am not interested in being told to try it myself, read the reviews, talk to others, or anything else. I would like to see that you believe in this product enough to do what is required to provide that information.

Should be easy based on your claims.

If you could do it, you'd get a ton of buyers.

Course, I'd bet you can't.

I can see that you are not prepared to believe there can be such an audible difference.


Is belief required? That certainly explains a lot. How about evidence?
 
Last edited:

Geert

Major Contributor
Joined
Mar 20, 2020
Messages
1,938
Likes
3,526
Hi Folks, Just wanted to revisit this thread with my latest findings: "The Sound Of Music and Errors in Speaker Cables"

https://mcusercontent.com/37242be22...Music_and_Error_in_Your_Speaker_Cables_1_.pdf
Some questions and observations:
  1. On page 5 and 6 you compare the performance of your Isolda cable to an artificially constructed cable consisting of "cable strips separated by about 300 mm to 500 mm, in two entirely separate bundles". I guess this test is intended to proof a certain point, but as the electrical properties of the artificial cable don't correspond to those of a typical speaker cable the test says nothing about the audibility of the demonstrated effect in normal conditions. I think it would be fair to include a comparison with a typical speaker cable in the demo (video).
  2. In paragraph 3 you reference a book to proof the existence of reflections in transmission lines. To be complete it's worth mentioning this book also mentions "When an electrical source is connected to a load via a “short” transmission line, the loads impedance dominates the circuit. This is to say, when the line is short, its own characteristic impedance is of little consequence to the circuit’s behavior" and "A rule-of-thumb for transmission line “shortness” is that the line must be at least 1/4 wavelength before it is considered long". What this rule of thumb means is that in practice for short lines the effect of reflections is neglectable. If you don't agree it would be nice to clarify this with some calculations (applicable to audio frequencies and typical equipment)
  3. In paragraph 5 you show how a mis-matched load causes ringing. From a simulation you did in Spice earlier in this topic we know the frequency of the ringing is about 3Mhz. That's clearly inaudible. There's also a simulation done by DoneH56 (https://www.audiosciencereview.com/...-analysis-of-speaker-cables-reflections.7154/) that demonstrates the effect does not exist when using a bandwidth limited input signal. Although your second test is also artificial and the observed ringing effect is not proven to be audible you apply the results directly to practical situations, which looks to me like your jumping to conclusions.
  4. At the end of section 5 you conclude "The results of these measurements, both by scientific measurement and by listening tests, would appear to demonstrate conclusively why the various designs of speaker cables sound different from each other". For the measurements to be scientific it would help if they would mention or show signal levels, periods or frequency where applicable. For the listening tests we miss a controlled double blindtest between a typical speaker cable and an impedance matched cable.
  5. It's difficult to agree with the final conclusions in section 6 given the remarks listed above. You might be on to something, but critical readers will still have a lot of questions.
Looking forward to your feedback as I'm interested to learn.
 

Max Townshend

Active Member
Audio Company
Joined
Mar 22, 2019
Messages
129
Likes
30
Hi Geert,

Thanks for commenting.

1. I have done this experiment many times and have found that widely spaced conductors have low capacitance and high inductance. When I said "bundles" it was, for the video, bundled together in two lots 300 to 500mm apart. It was interesting to separate the bundles/coils/tidy up and move the conductors around, getting closer (higher C, lower L) etc, the error voltage changed, as expected, on the error graph.

2. When employing "long" lines as in radio transmitters, it is vital to get Zo correct, or you get a brown smell.

practice for short lines the effect of reflections is neglectable. It's fine for ordinary signal transmission, but in the case of high fidelity, the minuscule must not be neglected. There is debate about the sound of capacitors, resistors, connectors, contacts, cable risers and more. Few of these things can be measured, but here is an experiment which anyone can do and you can see it and hear it.

3. Yes, we have jumped to the conclusion; With a matched cable and load, the signal is completely absorbed by the load with no reflections. With a mis-matched load, there are continuous, multiple reflections triggered by every change in the music, and it takes time for each transient to be completely absorbed.

see Deletraz. Fig 10. and Black. Please read carefully.

4. White noise is used, as it is frequency independent and level independent. The results are the same whatever level you use (no brown smells please).

5. Great to see an open mind and thanks.

I will answer any question and am thinking of doing a Zoom session with the tester live and showing the results real-time, and discussing. Is anyone interested?
 

win

Senior Member
Joined
Jun 17, 2020
Messages
430
Likes
432
Location
Irvine CA
I will answer any question and am thinking of doing a Zoom session with the tester live and showing the results real-time, and discussing. Is anyone interested?

TIME AND PLACE
 

scott wurcer

Major Contributor
Audio Luminary
Technical Expert
Joined
Apr 24, 2019
Messages
1,501
Likes
2,821
Hi Geert,

Thanks for commenting.

1. I have done this experiment many times and have found that widely spaced conductors have low capacitance and high inductance. When I said "bundles" it was, for the video, bundled together in two lots 300 to 500mm apart. It was interesting to separate the bundles/coils/tidy up and move the conductors around, getting closer (higher C, lower L) etc, the error voltage changed, as expected, on the error graph.

You're stating the painfully obvious here, how could you increase the space between two conductors and have anything else happen?

Speakers in general are far from resistive loads (and rarely the rated 8 Ohms) except at a few frequencies, you even show that.
 

Speedskater

Major Contributor
Joined
Mar 5, 2016
Messages
1,610
Likes
1,333
Location
Cleveland, Ohio USA
2. When employing "long" lines as in radio transmitters, it is vital to get Zo correct, or you get a brown smell.

practice for short lines the effect of reflections is neglectable. It's fine for ordinary signal transmission, but in the case of high fidelity, the minuscule must not be neglected.
While I'm not sure what a long or short line might be. But a wavelength at 1 megahertz is 320 meters. So a wavelength at 1 kilohertz is 320000 meters
 

scott wurcer

Major Contributor
Audio Luminary
Technical Expert
Joined
Apr 24, 2019
Messages
1,501
Likes
2,821
While I'm not sure what a long or short line might be. But a wavelength at 1 megahertz is 320 meters. So a wavelength at 1 kilohertz is 320000 meters

You are looking at this the wrong way, you can put a speaker cable into an RF test fixture and observe the transmission line behavior (as long as the cable does not have excessive dispersion) this is the snake oil pitch. The fact is that this behavior is far beyond audio frequencies and no music signal could ever even remotely excite any of this. Beyond that a speaker is a horrible termination in the RF sense, simulations with ideal loads are meaningless.
 

mansr

Major Contributor
Joined
Oct 5, 2018
Messages
4,685
Likes
10,700
Location
Hampshire
While I'm not sure what a long or short line might be. But a wavelength at 1 megahertz is 320 meters. So a wavelength at 1 kilohertz is 320000 meters
The speed of light must be higher than usual where you are. As for what's long or short, there is no strict cutoff. Commonly used values are in the range of 1/10 to 1/4 of a wavelength. Regardless, for the upper end of the audio spectrum, we're looking at a kilometre or more.

The justification for these silly cables is so riddled with flaws that I see no point in discussing it further.
 

Speedskater

Major Contributor
Joined
Mar 5, 2016
Messages
1,610
Likes
1,333
Location
Cleveland, Ohio USA
You are looking at this the wrong way, you can put a speaker cable into an RF test fixture and observe the transmission line behavior
Both Cyril Bateman and Bob Cordell have written about speaker cables at radio frequencies. But that's a different (very technical) discussion.
 

Max Townshend

Active Member
Audio Company
Joined
Mar 22, 2019
Messages
129
Likes
30
The spikes are showing some minor roll-off (around -0.6dB) from 50kHz. This is linear 'distortion' and while he claims it shows 'distortion' in audio frequencies a slight roll-off at 45kHz can hardly be called "visible distortion in the audible band".

The 'better' cables do extend a bit further in frequency range but will that really be audible ?

A High capacitance cable might not be the best idea for some amplifiers.
This might make some amps unstable and may ring/oscillate at very high frequencies with some speakers.

I also see this table of measurements:

View attachment 23965
You then say:

How did you get to 8 ohms? I don't know which one of the above is yours but taking the highest one at 88 milliohms/meter, 10 meter length would be 20 meters roundtrip = 0.088 * 20 = 1.76 ohms, not 8 ohms. How did you get to 8 ohms for DC?
You are confusing resistance and impedance. see attached and
 

Attachments

  • Characteristic impedance at DC.pdf
    158 KB · Views: 159

Max Townshend

Active Member
Audio Company
Joined
Mar 22, 2019
Messages
129
Likes
30
The speed of light must be higher than usual where you are. As for what's long or short, there is no strict cutoff. Commonly used values are in the range of 1/10 to 1/4 of a wavelength. Regardless, for the upper end of the audio spectrum, we're looking at a kilometre or more.

The justification for these silly cables is so riddled with flaws that I see no point in discussing it further.

How come there is a difference in the sound on the video and a difference in responses in fig 3?
 

SIY

Grand Contributor
Technical Expert
Joined
Apr 6, 2018
Messages
10,386
Likes
24,752
Location
Alfred, NY
How come there is a difference in the sound on the video and a difference in responses in fig 3?

How come lumped parameters give correct answers?

The unlabeled y-axis is a nice touch.
 
Status
Not open for further replies.
Top Bottom