Beyond the Ariel - Page 763 - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

Multi-Way Conventional loudspeakers with crossovers

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 23rd March 2012, 01:14 AM   #7621
diyAudio Member
 
Lynn Olson's Avatar
 
Join Date: Jul 2004
Location: Northern Colorado
Quote:
Originally Posted by IslandPink View Post
There are a few others Lynn, I had a long list of candidates once from James D who you may know and whose judgement I trust.
The others I can suggest are the SME 3012 II and the 3012 I ( heavier, better ) both a bit pricey on Ebay these days, but likely better than either of these is Thomas Schick's arm -

Schick tonearm

Which I have had rave reviews on, from another correspondent who has an all-valve system and used to use the Mk. 1 3012 . You may have seen his prototype at ETF in 2004 or 2005 . Ok, it's about E900 so not cheap ...
Well, PM me if you want to keep the long list of candidates off the forum, otherwise I think we'd all like to know. Tonearms are very subjective animals, with so many differences attributable to near-invisible differences in construction, and the arcane stick-slip behavior of bearings as the arm wobbles back and forth from small record warps.
  Reply With Quote
Old 23rd March 2012, 11:42 AM   #7622
diyAudio Member
 
Join Date: Oct 2005
Ha ha !
I'm not trying to keep it secret, just need to dig out the actual message from thousands I have from James. Unfortunately I've just finished work for about 10 days hol, and I think that message was on my work e-mail , ooops . I WILL get back to you on this, but bear in mind some of the ones he rated highest were well-known ( expensive) favourites like the 1st-model SME 3102 , and the Fidelty Research FR-64 . This info was applicable to all the low-compliance cartridges like 103,103R , SPU, EMT ( various) as I know James only rates these types. For the 103R ( not the SPU ) there is one unlikely winner which is the rather insubstantial-looking Mayware formula IV unipivot, which can be made to work very well if the headshell is loaded-up with 5-10g of lead ( shim ) . The midrange and treble are glorious , with that beautiful fluidity you get from unipivots.
Oh, yes, a longer , heavier unipivot would be the ultimate, and James's very favourite I believe is the top-model Morsiani arm from Italy .
  Reply With Quote
Old 23rd March 2012, 02:53 PM   #7623
diyAudio Member
 
slowmotion's Avatar
 
Join Date: Nov 2002
Location: Norge
I'm almost afraid to mention it, but apart from long(ish) conventional tonearms,
tangential tonearms work very well with the SPU and the Koetsu and so on.
A bit more fiddly to work with, tho.
  Reply With Quote
Old 23rd March 2012, 04:37 PM   #7624
soongsc is offline soongsc  Taiwan
diyAudio Member
 
soongsc's Avatar
 
Join Date: Mar 2005
Location: Taiwan
Click the image to open in full size.
Click the image to open in full size.
__________________
Hear the real thing!

Last edited by soongsc; 23rd March 2012 at 04:44 PM.
  Reply With Quote
Old 24th March 2012, 12:32 PM   #7625
AJMARS is offline AJMARS  France
diyAudio Member
 
Join Date: May 2010
Quote:
Originally Posted by IslandPink View Post
Ha ha !
I'm not trying to keep it secret, just need to dig out the actual message from thousands I have from James. Unfortunately I've just finished work for about 10 days hol, and I think that message was on my work e-mail , ooops . I WILL get back to you on this, but bear in mind some of the ones he rated highest were well-known ( expensive) favourites like the 1st-model SME 3102 , and the Fidelty Research FR-64 . This info was applicable to all the low-compliance cartridges like 103,103R , SPU, EMT ( various) as I know James only rates these types. For the 103R ( not the SPU ) there is one unlikely winner which is the rather insubstantial-looking Mayware formula IV unipivot, which can be made to work very well if the headshell is loaded-up with 5-10g of lead ( shim ) . The midrange and treble are glorious , with that beautiful fluidity you get from unipivots.
Oh, yes, a longer , heavier unipivot would be the ultimate, and James's very favourite I believe is the top-model Morsiani arm from Italy .
With this kind of cartridges (103, SPU, Koetsu, AT33, EMT), stiff ones (not reallt the EMT... but), the Fidelity Research FR66S will probably be a very good, stable and versatile choice... The problems are that you will need a large enough turntable to install it, the turntable has to be very heavy, you'll never be able to use a high compliance cartridge, and it is not cheap.... But if you use a stiff cartridge (and play a little bit with the headshell), what a pleasure (and easy to trim with the B60 base).

Andre
Attached Images
File Type: jpg FR66S....jpg (112.3 KB, 693 views)

Last edited by AJMARS; 24th March 2012 at 12:37 PM.
  Reply With Quote
Old 24th March 2012, 11:20 PM   #7626
kevinh is offline kevinh  United States
diyAudio Member
 
Join Date: May 2007
The Well Tempered is very good at a sane price, well thought if a bit out of the box.

Well Tempered Lab - Amadeus
  Reply With Quote
Old 26th March 2012, 06:21 AM   #7627
diyAudio Member
 
Lynn Olson's Avatar
 
Join Date: Jul 2004
Location: Northern Colorado
Thanks, Island Pink, for the Shick link. The bearing discussion is very interesting - I feel the bearings are at the heart of what a tonearm does, since they are the most uncertain element of the mechanical linkage between the turntable structure and assorted mechanical noises created by the cartridge (what is sometimes called "needle talk").

Since the cartridge noises are highly resonant in character, the effect they have on the bearing is very important. One school of arm design uses a lossy (typically wood) arm shaft, while the more common approach uses metal cylinders (which are very efficient at transmitting cartridge noises into the bearing assembly).

This is akin to the mechanical path between the driver frame and where the floor meets the loudspeaker enclosure. There's one school that believes in decoupled driver frames (flexible mounts, etc.), and the other, a rigid path from frame to floor. The Ariel is example of the second school, with the rigid front panel coupled to the floor, and internal elements in the enclosure that go from front panel to floor.

Perhaps a more useful model is the mechanical impedance (versus frequency) that the cartridge (or speaker driver) sees looking into the headshell or armtube. Resonances in the armtube (or speaker enclosure) represent narrowband shifts in this impedance, and mechanical coupling elements that generate noise (like bearings) are a secondary distortion and noise source.

Although a lossy bearing (like a wire under tension) is intellectually appealing (low bearing noise), the string goes into its own set of harmonics, and represents a dead-end for the mechanical energy coupled into the armwand. It's a good question what happens with a unipivot - lower bearing noise, of course, but the mechanical path to ground is questionable, as well as uncertain azimuth as record warps are traversed. (Record warps on even the smoothest discs is always far larger than groove modulations.) Another question is how lateral (center image) energy is handled differently than vertical (out-of-phase) energy; the differences in mechanical impedance (as seen from the cartridge) will affect the spatial properties of the soundfield.

There are similar and interesting challenges for loudspeaker design. Aside from the desired conversion of current into mechanical back-and-forth motion in the voice coil and former, there is magnetic flux variation that is reflected into the ceramic, Alnico, neodymium, or field-coil magnet (which have some degree of compliance and acts as a nonlinear load), and the mechanical reaction forces that appear on the driver frame. Neither is that easy to measure, but are quite real and affect the sound. Even the simple strategy of trying different flat platforms under a loudspeaker (made from metal, wood, MDF, glass, marble, slate, etc.) reveals surprisingly large subjective differences. Small changes to the magnetic structure of a loudspeaker are also quite audible, although not immediately obvious on THD curves.

The fact that any difference is audible reveals just how significant these stray mechanical energies are. The same applies to the digital domain; that any difference is audible between various jitter-reduction schemes (cables, asynchronous reclocking, FIFO buffers, low phase-noise clocks, etc.) indicates that a seemingly minor parameter is actually quite important in subjective terms.

These weird little "problems" - from the viewpoint of mainstream designers - are a powerful insight into secondary "side-effects" where the physical device departs from the standard textbook model, and are quite illuminating in pointing the way forward for more research. If a seemingly small change, that does not seem to affect the standard model, yet results in a large subjective change, that's a good direction to look for improving the measurement system so it better matches what is heard.

Last edited by Lynn Olson; 26th March 2012 at 06:51 AM.
  Reply With Quote
Old 28th March 2012, 05:04 AM   #7628
system7 is offline system7  United Kingdom
diyAudio Member
 
system7's Avatar
 
Join Date: Aug 2008
I'll just throw in what I thought was one of the neatest solutions to isolating a turntable plinth I ever saw, can't remember who made it...

The SME arm and Garrard 401 turntable was mounted on a solid wooden plinth, but the whole thing was suspended on two straps of elasticated furniture webbing within a rectangular wooden frame. You had to see this thing rocking gently backward and forward while tracking securely to believe. Best mounted on a solid wall of course. Looked a bit like the old SME plinth, but NO SPRINGS.

The acoustic isolation from vibration was quite superb. Your engineering problem reduces to simply the plinth, turntable and arm mounting as a closed system.
Attached Images
File Type: jpg Garrard_401_SME_Plinth.JPG (55.8 KB, 523 views)
File Type: png Floating_plinth_Garrard_401_SME_webbing.png (11.6 KB, 434 views)
__________________
Well, there it is! Best regards from Steve in Portsmouth, UK.
  Reply With Quote
Old 29th March 2012, 06:25 PM   #7629
system7 is offline system7  United Kingdom
diyAudio Member
 
system7's Avatar
 
Join Date: Aug 2008
The decoupled/damped versus rigid/undamped debate is an interesting one whether in loudspeakers or record players.

I think the verdict is you go for rigid construction as a first design goal to get resolution, and then apply a path to dissipate energy in the right place. SME are willing to discuss their turnaround on fostering light floppy construction for high-compliance magnetic cartridges in the seventies, back to the sort of heavier arms with tensioned bearings suitable for better low-compliance moving-coil cartridges.
SME - Series V

You don't have to read it all, but they wanted to get plinth support resonances around 2 Hz and arm resonances nicely separated around 8 Hz, with signal above 20 Hz. Damping is then lastly applied to an optimum undamped solution. Makes sense.

I have previously mentioned how useless most magnetic cartridges are. The high inductance Shure designs ended up with a second-order high frequency LC response that had the stylus moving at 180 degrees to the groove as in the Rod Elliott plot at high Q. It wouldn't matter with a microphone, but for a cartridge that means mistracking.
Magnetic Phono Pickup Cartridges

By contrast, designs like the Grado and venerable 1960's Decca London worked at first-order high frequency, so were much sweeter sounding, albeit they need a heavier tonearm to avoid overexciting arm resonance.

That's a long post by my standards, sorry. Seems to me you get it all rigid, but then think about how to dissipate the energy with one fell swoop. Maybe sandwich construction is a viable solution. Glue a piece of granite to a piece of wood in your plinth, and the energy can dissipate. Many ways to skin a cat. It's all physics in the end.
Attached Images
File Type: jpg Rod_Elliott_magnetic_cartridge_frequency_response.JPG (50.8 KB, 114 views)
File Type: jpg Record_playing_cartridges.jpg (96.0 KB, 76 views)
__________________
Well, there it is! Best regards from Steve in Portsmouth, UK.
  Reply With Quote
Old 1st April 2012, 10:10 PM   #7630
diyAudio Member
 
Lynn Olson's Avatar
 
Join Date: Jul 2004
Location: Northern Colorado
Now that I've been looking more deeply into the speed-stability issue, there are some very strange problems with suspended TT's with a motor rigidly attached to the non-moving base/plinth.

Most TT suspensions have a very high Q - in other words, they take a long time to settle from an initial shock, like a car with worn-out shock absorbers (dampers). Anyone that's ridden in a car like this will quickly feel seasick from the constant wallowing motion, since road shocks continually re-excite the high-Q 2nd-order lowpass filter (springs and mass of car). One little trick that car manufacturers learned in the early Sixties were staggered spring rates for front and back, with about a 15% difference in spring rates, so the system as a whole would settle more quickly, and not be as prone to go into nauseating front-to-back rocking motions. Cars made in the 1950's with American-soft suspension were notorious for sickening the passengers - I remember this all too well from my own youth. I still prefer firm suspensions, partly for that reason.

I've noticed that suspended TT's with either 3 or 4 springs can take an amazingly long time to settle from a single shock - sometimes as long as a minute, which implies a very high Q in the range of 20 to 100. This is just poor design; in real-world environments, the TT will always be in motion, unsettling the tracking force on the tonearm and having a very complex effect on the gyroscopic momentum of the platter. Give the system a good shove while the platter is turning, and watch the initial lateral motion turn into high-order rocking modes, as momentum is transferred from one spring to another. (Asymmetric distribution of mass will result in simple lateral shocks gradually growing into much more complex rocking and rotary motions - they'll get smaller, but there are many more of them, moving in more dimensions.) When the TT finally settles, you'll notice the final motions have no relationship at all to the original shock.

It gets much worse if the motor is stationary while the platter moves around; that changes belt tension (never a good thing), as well as the effective location of the motor (relative to the platter). In other words, the power fed into the belt will shift as the platter moves around, and the power surges stored in the compliance of the belt will then independently excite the spring suspension and keep them in motion.

A motor that is not part of floating suspension is going to have a very poorly defined lowpass filter between the motor and platter. If the platter is free to move laterally - and with springs, it will be - it will surge back and forth if environmental shocks get the springs moving, which leads to uneven power delivery, as well as a high-Q lowpass filter that actually stores energy, instead of filtering it out.

High-order (2nd-order and above) filters that have dynamic elements introduce a lot of problems. One example are MM cartridges where the cartridge inductance and phono-cable capacitance form a 2nd-order lowpass filter in the 14 to 22 kHz range. This seems innocent enough until you realize that both the inductance and cable capacitance are low-quality LC elements, nothing like the sort of thing you'd use in the RIAA section of a phono preamp, so the lowpass filter is not well defined under dynamic conditions, and introduces significant time-domain distortions of its own.

If you must use a high-inductance cartridge (typically these require a stated cable capacitance to measure flat), better to use as little capacitance as possible, and HF equalize in the preamp at a location that is electrically isolated from the input circuit. That way, you can hear the cartridge by itself, instead of a resonant 2nd-order lowpass filter with a bad capacitor (even astronomically expensive cables make pretty bad capacitors).

In loudspeakers, most of the reason I use Zobel inductance-cancelling RC networks is to isolate the low-quality VC inductance from the crossover network. I go to a lot of trouble to build the crossover from the highest-quality parts I can find, and I don't want them dancing a tango (forming a filter function) with the really low-quality VC inductance, which is a dynamic, program-controlled inductance with high-order nonlinearities (compared to an air-core inductor).

To return to the original premise, one of the things to avoid in audio design is transforming a simple problem into a more complex high-order one (that might measure better but not sound better). In amplifiers, if the loop feedback or power-supply regulation is disturbed by transient current surges, the performance of the amplifier can greatly degrade while the loop is stabilizing itself. In extreme cases, if the loop cannot return to stability, the amplifier will be destroyed, and possibly take out the speaker as well. In milder cases, the loop might take a long time to settle, and go through chaotic modes as it does so (chaotic modes are fairly common in complex feedback circuits, especially those with nonlinear elements).

Loudspeakers typically have lower-order behavior than amplifiers (lacking a power source, they can't oscillate), but high-order modes in the cabinets need to be chased out, and crossover networks need to be examined to see if they behave differently with different amplifier source impedances and also examined to see if nonlinear terms in the driver are interacting with the network.

It's not immediately obvious, but if you suspended a direct-drive TT, the feedback correction loop might take longer to settle, which is not a good thing. This is easy enough to examine by giving the TT a good shove and seeing how long it takes the servo-correction error signal to settle to zero.

Last edited by Lynn Olson; 1st April 2012 at 10:39 PM.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



New To Site? Need Help?

All times are GMT. The time now is 04:09 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2