I share the surprise of learning of Chinese sourced components. I am gradually making sense of the history and can speak more readily after the Thiel bankruptcy closes.
I will say that Jim's decisions were careful and considered. I know that FST, the Chinese manufacturing source, was chosen for Thiel's Home Theater product components in the mid 90s and that Jim worked with them in his last years on the 3.7 drivers, which could not have been developed any other way.
So, even though I and many others judge Chinese components less worthy, the facts may not support that opinion. However, my own research and observations lead me to return to Thiel's traditional use of best-of-form sources which are generally European, Japanese and/or American. So much subtle sophistication goes into creating the very best of anything, that I don't trust even an ISO 9001 spec unless I verify the results for myself.
I have learned that the CYC caps in the 3.7 use a Chinese film claimed to be equivalent to the best. Solen and most other very sophisticated brands use it also. I believe from trustworthy input that that film underperforms the best-in-world Japanese and Danish film, from which Thiel's prior custom caps were wound. I am returning to known best of form suppliers even if the Chinese suppliers might be as good. I would have to prove it for myself.
In the case of wire, Beetlemania's 2.4 coils were from the Chinese source with same claims as above. I can't compare wire alloy or manufacture methods and specs, but I can say B's 2.4 coils were visibly inferior in wind quality. Thiel's known ERSE and Jantzen coils are my choice. And so forth and so on. We only know what we know. We don't know what rigor or trade-offs were applied to late Thiel products, especially after Jim's death, but even before that. I saw a photo of Jim showing off a CS3.7 crossover with all CYC caps.
For my part, I plan to create iterations that best serve the musical capabilities of the design intent.
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While a heavier gauge in a single conductor may allow a higher capacity, I am curious how signal response across the contemplated frequency range through such increased conductor cross section would be impacted. Perhaps a multiple optimum conductor scheme would be a more desirable arrangement under such circumstances, or over longer distances where such frequency distortions are compounded.
I think the trick is to design a cable that does not really favor any particular frequency. It is easy said than done though. You don't want to for example emphasize high frequency but not at low frequency - you then end up with a cable that sound bright and edgy. And you don't want a cable that has resonance issue at some specific frequencies either(I suspect some low end Monster cables suffer from this condition). As far as having gauge size of 18AWG as optimal, that's an interesting observation. 18AWG itself may be too small to drive a speaker as it may not be able to carry a lot of current without experiencing a lot of phase shift. One way is to bunch together a lot of 18AWG wire then run them on a dielectric substrate so you can have the best of both world - low distortion of 18AWG but able to carry a lot of current. A lot of cables use this strategy especially at the high end spectrum. I looked at StraightWire website and it seems like the as the cable cost gets higher, the construction becomes more complicated in term of number of wire strands and dielectric arrangement. It's interesting that high end cables is only a recent phenomenon. I was not around back then but in the 70's or 80's it was not an area where people were paying that much attention. Personally cables in my system have made the most prominent differences given their modest cost compared overall to my system. Anyway, cables is an interest area of mine but as I said I don't mean to discuss too much on cables as this is mainly a Thiel thread. |
@jafant
Yes, I have 163/164. What a memory!
Given that the SE was released before Jim T passed in 2009 and my pair was built in 2012 (as reported by the seller and confirmed per label on a woofer), I suspect SEs were built as orders trickled in. But it’s hard to imagine that your even newer pair does not also have FST sourced boards. Obviously, you are plenty happy with your sound, so all is good.
In my case, I was very happy with the OEM boards but heard a slight “glassy” quality in the midrange. Encouraged by Tom Thiel’s participation here, I upgraded the resistors which cleared that issue and provided other sonic benefits. And now I have made global changes and am discovering what the Thiel CS2.4s are capable of. Literally put a smile on my face. |
Andy - my first-choice idea for multiple runs is to twist the bunch (2 or 3) 18 ga varnished coil wires having essentially no dialectric. That wire-twine is insulated with a cotton sleeve (very low dielectric absorption) if physically necessary - and/or physically kept from contacting its opposite polarity mate or other conductor. Driver runs will require spacers so that the ± twine-pair can be twisted to reduce capacitance. I am looking at teflon donuts for that purpose.
Much of the insulation requirement for speaker cables and interconnects is due to handling, being stepped on and so forth. Inside a speaker cabinet is a safer, more predictable environment.
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Regarding the FST coils, I sent pics to Tom Thiel and he noted the apparent loose winding. When my new ERSE and Jantzen coils arrived, I was stunned at the difference in tightness of the windings. Given my global changes, I cannot say to what degree replacing the coils has improved SQ.
I was surprised at the CYC caps on my OEM boards and an Internet search revealed little about their quality or construction. But I was especially disappointed to discover that they are MKT (polyester) instead of MKP (polypropylene). As I suggested in my previous post, there is nothing “wrong” with their sound, but other caps have better SQ. Earlier 2.4s apparently have MKP caps.
I was unable to determine the manufacturer for the resistors but they superficially resemble those on Lexington boards I’ve seen on the ‘net. Nevertheless, replacing those with Mills MRA-12s was money well spent.
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beetlemaniaPutting a smile on our faces is what it is all about my friend.As soon as Tom and You have finished products, I want to visit and hear the outstanding improvements. No rush- enjoy this hobby and the Music!
Happy Listening!
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Hi beetlemania and Tom,
I am wondering if you could comment on the sound improvement of the CS2.4 given various xover upgrades? I think you have said there was improvement but could you elaborate a bit more? I understand it's hard to describe sound quality in verbal language but if you could give some impression on the improvement over the stock xovers?
Thanks. |
@andy2 Keep in mind that my SEs had FST boards. Compared to (most?) standard 2.4s, these have better coax feed caps but potentially worse caps and coils elsewhere. Here is what I wrote regarding the Mills resistors https://forum.audiogon.com/discussions/thiel-owners-2/post?highlight=Mills&postid=1555245#155524...Also https://forum.audiogon.com/discussions/thiel-owners-2/post?highlight=Mills&postid=1562426#156242...In hindsight, I would add that the Mills completely removed the “glassy” quality I was hearing and also made extended listening more relaxing. My more recent work has replaced the boards entirely, with the Mills kept. I’m not yet at a final configuration, auditioning another cap combo and still plan to replace input/output wiring plus terminal posts. That said, direct comparisons in mono revealed the new boards to have notably more resolution and transparency. The FST (with Mills resistors) was relatively veiled (yeah, I know) and muddied. The new boards have textures and microdynamics previously unnoticed. I hear an ease of presentation and more presence/immediacy. These improvements sound evident for all instruments and voices. Bypass caps make a more subtle improvement. Just a scotch more resolution with improved transients, “jump factor”. Listening in stereo with the new parts in both channels is when I smiled. For the last many months I’ve been hyping an opinion of what might be possible with better passive parts. I, um, wasn’t wrong . . . |
beetlemaniaThank You for your continued dedication, experimentation, research and testing to find the final configuration. I am excited, can hardly await to hear your improved XO. Happy Listening!
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Beetle - thanks also from me for your steady, careful implementation, especially when backing out of blind allies.
You all may be interested to know that the 03, 03a/b, CS3, CS3.5 and CS2 had styrene micro bypass caps (0.01 and 0.015uF), similar to (but not as good as) the RTX bypasses. They were dropped @ CS2.2 and CS3.6 and onward. Those earlier models also used the French polypropylene Solens @ 400 volt and German polystyrene x tin foil 1uF, both best in world at the time. Those companies ceased making film, and replacement caps gradually became more ordinary. I suspect that some of the love for the CS3.5 might be attributable to those pristine caps and double bypasses.
In this project we are using best of form caps that exceed anything Thiel had ever used, including those described above. Thanks again to Beetle for making various controlled comparisons. I will be making more.
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tomthielLooking forward in reading more about your observations as well as Beetle's configurations. Over the years, reading across multiple Audio forums, I have read about the right phase angles. In the models CS 2.4, 2.7 and 3.7, the first right phase angle occurs at 200 Hz. A second right phase angle occurs at 100 Hz. Have you guys (Andy, Beetle, Holco or Tom) found this problematic for your personal system power amps to drive? As I understand it, this is correlated in drops between 4 Ohms down to 2 Ohms across much of the speakers' frequencies. 3 Ohm nominal.
This is one indication as to the value of using a 2 Ohm stable power amp to (hopefully) prevent clipping and distortion within the mid-bass/mid-range regions. Thus, reducing damage to crossover and driver.
Happy Listening!
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@jafant
I have never noticed any stress from my Ayre AX-5 at any SPL in my 18x19 room (vaulted ceiling with large openings on rear wall). With my combo of amp and DAC, clipping sets in at an indicated “40” on the volume with a typical CD. Even for something like Zeppelin or The Who, “32” is plenty loud for me. I have plenty of headroom. |
Mr. Beetle - I have routinely used Mills wirewounds in my own crossover rebuilds and upgrades over the years. And they have routinely been an improvement in nearly every instance. I am glad that your experience has confirmed my own. They are quite good.
But I will add this. I have learned that materials and parts selection, and their implementation, is as much of as an art as a science. That process of ’voicing’ more approximates a very complex cooking recipe, where some ingredients balance and offset against others, and must be combined in a careful blend.
While normally the superior materials and parts prevail, some of the critical listening outcomes can be quite surprising, indeed.
As an example, I am always reminded of one of my favorite stories involving David Hafler, who many years ago was voicing one of his amplifier designs, and was working out the selection of one particular coupling capacitor. While the design team had access to every conceivable exotic capacitor design, including those with copper and silver leads, a very simple, very humble, and very inexpensive steel-leaded model always prevailed in every single listening test. The amp went to production with that inexpensive steel-leaded capacitor.
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sgmlaw - your Hafler story represents the approach of a wide range of designers, and practically the entire DIY community. I will offer a different perspective which included Nelson Pass, John Dunlavy, Benchmark's John Siau and Jim Thiel to name a few.
That Thiel approach says that in a situation where an inferior part creates a better sounding outcome - that is evidence of another problem. Something else is going on which has not yet been identified.
Your Hafler experience happened routinely in Thiel product development. As a matter of process, we took that outccome back to the lab to figure out what was happening. Usually that "fix" was masking something much like dither noise masks or randomizes artifacts of digitization. Our MO was that a solution had to both sound better and measure better or our work wasn't finished.
I recognize that I am speaking anathema to many or even most of you. But I offer it as a signpost along the Thiel road.
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beetlemaniaThank You for reporting on your Ayre AX-5. I poised the query to address integrated amps, as well as, separates. The notion was in the back of my mind last week during my time spent with the Pass Labs (very robust for a 150w into 8 Ohms) power amp. We all know that some manufacturers do not list 2 Ohm specs. Surely, those great designers behind Audio Research, Ayre, Conrad Johnson, Parasound and Pass Labs, test those loads on the bench.
Happy Listening!
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@sgmlaw
I agree there is a good amount of art to voicing a XO. But know that Tom T has put in a mountain of homework, drawing on his own experience and that of several industry professionals with decades of knowledge/experience. The idea for these kits was introduced about one year ago and here we are still in beta version for the first model tackled. Tom has been quite deliberate and considered in his approach and has been willing to change his plan as new information is encountered.
But even a full-time designer cannot listen to all the possible combinations. Let me just say that I lack sophisticated measuring tools but what I do have confirmed that the overall balance was not upset. And, to my ears, the end result is spectacular. |
profThank You for the PM. I enjoyed reading your speaker shoot-out from last year. You auditioned quite a number of different loudspeaker brands. Very informative, insightful. Happy Listening!
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JA - I suspect you haven't gotten satisfaction re your impedance / phase query. Technical study and understanding underlies amp loads. Here's a superficial sketch: Impedance (AC resistance) can be mechanical, electrical, inertial, etc. Voltage is the driving force. Current flows during motion / work. Phase shift occurs when current (work) lags or leads voltage (motive force). That situation exacerbates amplifier difficulties. Changing impedance and phase angles cause amp distress which is especially troublesome when reaching for max current delivery ie low impedance load.
You are correct that those top-tier, and probably all, designers know how their amp responds to 2 or 1 ohm loads under various phase angles. If that performance is exceptional or even good, they publish it. If not, they suggest its un-importance by their neglect.
Test specs can be misleading on many fronts. User success with a design proves its worth.
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Jafant,
My Audio-GD 40kg dual mono power-amp is super stable and drive's the CS-2.4 with verve, some specs, 2x 250W / 8ohm - 2x 500W / 4ohm - 2x 1000W / 2ohm and max 2x 1000W / 1ohm, higher loads than 1000W will tricker the protection, there was never a situation that I heard anything going wrong and I like playing loud some times, according to my wife most times ;) |
Have you guys (Andy, Beetle, Holco or Tom) found this problematic for your personal system power amps to drive? As I understand it, this is correlated in drops between 4 Ohms down to 2 Ohms across much of the speakers' frequencies. 3 Ohm nominal.
The impedance of a speaker can be a bit complicated (but it doesn't have to be). The other side is how the amp drives the speakers if the amp is a no-feedback or feedback design. In general, the higher the impedance is the better but that statement is a bit overly simplified since higher at some frequencies may not be good. In most speakers, the impedance is lowest at low freq. around 100 - 200 hz and rises toward the higher freq. The low freq is where most amp will have issue if it stays too low. I think the impedance of 3ohm or above is probably OK, but below 3ohm, some low power amp probably will have problem. At high frequencies, low impedance is usually not an issue since high frequencies do not demand as much current vs. low freq. As the freq. rises higher, you probably don't want impedance to get too high (due to inductance rising) which will result in treble harshness. In some speakers, there is an "impedance correction network" to reduce the rising impedance so that it won't be a problem for tube amplifiers. So this is where high impedance is not good either. As for impedance angle, it is mostly negative (capacitive) at low freq. and gets more positive (inductance) at higher frequencies. As long as there is not excessive swing from negative to positive, it should be fine. In general, you don't want the phase angle excessive negative at low frequencies and excessively positive at high frequencies. Too negative angle at low freq. will be hard to amp to drive. Too positive at high frequencies may result in treble harshness. In general, capacitive load demands more current and reduces dynamic, whereas inductive load causes high frequencies issue. The other side is the amp design. Some amp are design with no feedback and some with feedback. Most people agree that no feedback is better sounding vs. feedback. But amp with no feedback are more sensitive to speaker impedance swing so it is a trade off. Interestingly enough, most low cost amplifiers are designed with relatively high feedback because it costs a lot more to design a good amp with no feedback. Tube amps tend to be most sensitive to impedance since most of them are designed with very little feedback or no feedback at all and exacerbated because tubes usually don't have a lot of drive current. For those who are interested in feedback vs. no feedback argument, there is a good article from PASS lab that I included the link below: http://www.firstwatt.com/pdf/art_dist_fdbk.pdf |
tomthielThank You for addressing my query on right phase angles. I know that all of you guys are occupied with work and various other activities/interests.Looking forward to other contributors chiming in on their power amps outside of the Ayre, Classe', Krell, Mark Levinson and Pass Labs owners.Hope you are well today and enjoying your Hot Rod garage.
Happy Listening!
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holco,Thank You for citing the specs of your Audio GD power amp. Those ratings are incredible! With those figures, I have no doubt about under-driving your CS 2.4 loudspeakers. I have really enjoyed reading about your cross-over upgrade project as well. Glad you are a member of the Panel.
Happy Listening!
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andy2Thank You for providing your expertise as well. Agreed, amp design as it addresses feedback vs no-feedback is pivotal for our speakers. I try nt to get too tied up in the manufacturer specs as well. Reading across other Audio forum threads, other Thiel owners are enjoying some of the lesser known power amps and/or integrated amps with success. Along the lines of designers not citing 2 ohm power ratings, I also find, peak current delivery in amperes (A) not reported. John Atkinson of Stereophile fame and Paul Miller of HiFi News & Record Review fame do a pretty good job of reporting pertinent figures/ratings as discussed here.
Happy Listening!
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On another related thread, desmond888 , is working on a cross-over project upgrade as well. You guys check out his progress as your schedules allow. Very cool to have so many DIY guys making improvements and upgrades on an already Legendary design.
Happy Listening!
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JA - how do we access desmond's project. Or, can you get him to report here?
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@tomthiel This thread https://forum.audiogon.com/discussions/thiel-cs2-4-upgrade-to-cs-2-4-seDesmond put CSA 250V on the coax feeds (had to parallel 10+3.9 and 18+10 uF). He reported his perception of a change in balance and suboptimal neutrality and “clean”. Quite a different experience than what I’m hearing albeit his starting and ending points are very different. I wonder if his expereince is at least partly a function of burn in. Would be interesting to read an update. |
tomthiel
I did ask desmond888 to join us here once he has established a finished product. Beetle has posted the link to his particular thread as above. Thank You Beetle- I know that you guys have been talking back and forth. Exciting times indeed.
Happy Listening!
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@tomthiel This thread
https://forum.audiogon.com/discussions/thiel-cs2-4-upgrade-to-cs-2-4-se
Thanks beetlemania for the pic. Based on the pic, I drew up the schematic and I would like to make a few comments. Since this forum does not allow posting picture, I had to create a thread at DIYaudio.com so that I could post the schematic. Please see the link below. You could download the schematic in .png format. https://www.diyaudio.com/forums/multi-way/332679-thiel-cs2-4-xover-schematics.htmlHere are my comments on the xover upgrade: Mid+Tweeter xover: Since there are a lot of caps and resistors, it would cost a lot of money to upgrade them all. Here is the order in which I would prioritize: 1. Cap C1 & C2: these are the most significant since all the current will flow through these so I would upgrade these first. I would use some high end cap such as Mundorf supreme or Jantzen silver or equivalent. 2. Cap C8 has a 16ohm resistor in front of it, so the current through these will be very little so you probably won't need any expensive caps. I would use some basic audiophile grade quality cap such as Clarity. 3. Cap C6 & C7 may not be critical. They along with inductor L2 form a notch filter at around 2.5KHz and most of the time, there is no current through them. R4 is actuall more critical (see below) so again, use some basic audiophile grade cap such as Clarity. 4. Resistor R4 is next most critical since all the current will flow through these so I would use the best one you could afford. 5. Next up is resistor R1 and R2 which have relatively very large value, so they are not as critical as R4, but resistors are relatively inexpensive so I would replace them. 6. Cap C3, C4, inductor L1, and R3 are not very critical since they form a notch filter at around 150Hz, but since these electrolytic caps may be old so you may want to replace C3 and C4 due to age concern. These should be electrolytic since they are not very critical. Base xover: In general, at low frequency, the caps are not too critical, but since the CS2.4 crosses the bass and mid at relatively high freq. at around 1kHz, it may make a difference. Also, both caps C9 & C10 both are being formed with respective inductors so there is no point of buying expensive caps. I would keep the existing caps. But I would change the resistor R5 to something decent since there is still some current flowing through them. Although most of the current will flow through L3, it may be worth it to upgrade R5. |
I would like to make a correction from my post above.
3. Cap C6 & C7 may not be critical. They along with inductor L2 form a notch filter at around 2.5KHz and most of the time, there is no current through them. R4 is actuall more critical (see below) so again, use some basic audiophile grade cap such as Clarity. C6 & and C7 are critical so you should use high end cap such as Mundorf or Jatnzen silver or equivalent. |
@andy2
have you compared Clarity, Mundorf, and Jantzen (or others)? Which ones?
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have you compared Clarity, Mundorf, and Jantzen (or others)? Which ones?
I have used the Clarity CSA (the older version, not the latest one with their newer Copper Technology), Mundorf Supreme cap, and Jantzen Z-Silver. The CSA is OK I think but compared to the Mundorf supreme cap, it has a bit of a haze and the soundstage is a bit constricted and lacking three dimensionality. When I used the Mundorf Supreme, I was actually a bit surprised at the amount of improvement. There is additional soundstage bloom, more palpable, and a marked improvement in detail retrieval. For example, in Cowboy Junkies Trinity Session, the background noise of the recordings is quite a bit more apparent with the Mundorf vs. the Clarity. The Jantzen Supreme Z silver has everything of the Mundorf Supreme but adds a subtle layer of extra detail in the treble. It is very detail and may be just a bit too much detail on the treble but in a good way though. It also needs a longer break in time. If you have a high end setup, I would recommend the Jantzen over the Mundorf but both are very good and the difference is minimal. |
andy2
Great info!! Thanks :) |
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Hi andy2, what is your opinion on the 1uF foil caps (C2 and C7), why JT omitted it in the SE crossover? Before answering your question, let me just take a moment discussing the physics behind capacitor and inductor. Think of them as the ying and yang of circuit design. I am not sure if you're technically inclined but they act opposite of each other. The capacitor acts to slow down a current whereas the inductor acts as to speed up a current. Mathematically a capacitor is an integrator (a process of averaging) and an inductor is a differentiator (a process of diffrentiation which emphasizing the extreme). To make thing a bit more complicated, the larger the capacitor, it carries extra parasitic that is not part of the capacitor. The lower quality of the capacitor, the higher amount of parasitic. Therefore, there is a need to have a smaller capacitor in parallel for the higher frequency to get through bypassing all the parasitic of the large capacitor. If you have a really good capacitor, it would have less parasitic so it will not degrade the treble frequency so bypass capacitor may not be needed. So the purpose of C2 and C7 are meant to provide an extra path for the higher frequency signal therefore to improve the transient of the treble frequency. Now it's a matter of implementation. If you think your main capacitor is good enough, then C2 and C7 may not be needed. So it's your call. Although C2 and C7 improves the treble transient, the problem with running a large capacitor and a much smaller capacitor together is it may introduce jitter since the signal path is now unequal. Another way to implement it is to equally split the capacitance value in half. For example, if you want 14uf, it might be better to have two 7uf vs. one 13uf and one 1uf. Both implementation both adds up to 14uf, but the physics will be different hence the difference effect in treble. At the end, it'a a matter of fine tuning. For comparison purpose, most speakers have separate tweeter and midrange driver, therefor the tweeter xover on those speakers have very small capacitor in the signal path which is around 4.7uf to 6.8uf. For the CS2.4, if you count up all the cap in the signal path (14uf + 28uf = 42uf), that is quite a bit so the bypass cap is probably more important. Listening to the CS2.4 and my own design, I do feel my speakers have that extra treble details that is hard to describe but it's there. Some have mentioned that after the cap upgrade on the CS2.4, there is extra air and transparency so it may have something to do with that, |
"I have used the Clarity CSA (the older version, not the latest one with
their newer Copper Technology), Mundorf Supreme cap, and Jantzen
Z-Silver."
Andy - would you please clarify which ClarityCap you are referencing? The CSA has the copper ends.
Thanks, Tom
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Andy - would you please clarify which ClarityCap you are referencing? The CSA has the copper ends.
Hi Tom, Sorry, I got confused with all the acronym. The Clarity cap I used was "SA" and not "CSA". So I the Clarity cap that I used did not have the Copper Technology. Again, sorry for the confusion. |
Thanks for the reply, Andy. I’m pretty sure the C in CSA is for copper. Maybe your earlier experience was with Clarity SA? Tom Thiel suggested Mundorfs as a possibility for the coax feeds early last year and I considered those. From my reading, there is wide performance among Mundorfs, probably owning to their varied sources. Somewhat independently, each of us circled back to Clarity (in no small part after reading through a long capacitor thread on a’gon). The CMR range captured my imagination but Tom convinced me that CSA with a good bypass would have similar performance for less money (Thiel Audio’s MO). The Jantzens seem to be excellent and that is what @holco is using to great effect.
It’s been a couple of years since I’ve heard a top-$helf system but my upgrade captures what I recall of its SQ. Of course, the CS2.4 comes up short in low bass and a XO upgrade can’t help that but my upgrade has resolution, immediacy and transparency on par with the best I’ve heard. Musical immersion. The only criticism I can muster is that image density doesn’t match the best I’ve heard. Not sure whether it’s something with my set-up or room or the speakers. But I otherwise now have my own top-shelf system. |
Andy - thanks for the clarification. The C is for Copper in CSA and the CSA is reported to be a big step better than the SA. One day I will directly compare the SAs from the 2.4SE with the new CSAs.
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Got all the parts for the final upgrade, next thing is designing the layout on the new PCB's |
Andy - thanks for the clarification. The C is for Copper in CSA and the CSA is reported to be a big step better than the SA. One day I will directly compare the SAs from the 2.4SE with the new CSAs. Hi Tom, It will be interesting as what is the difference between the "SA" and "CSA". I personally am a bit doubtful as to how much the difference between the copper technology vs. the older "SA". Sometimes I think the marketing is getting ahead of the technology itself. I think for the most part, it’s the dielectric material of the capacitor that determines the quality of the capacitor and not the "copper contact". Without knowing more, I still would prefer capacitor that has the reputation such as the Mundorf Supreme or various Jantzen capacitors. |
@holco Take a look at this if you’re not already aware http://www.troelsgravesen.dk/coils.htmAlso, I previously suggested mounting resistors on aluminum to help with cooling when you had them buried under caps. Yeah, um, do *not* do that. It appears you will have more room on your new boards to fit everything and give the resistors some breathing room. |
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beetlemania,
I'm aware of the do's and don'ts placing coil's, how to placing coil's near capacitors is new info for me, thanks for the link :)
But like you said, there will be more space on the bigger PCB's, and if Jim Thiel didn't calculate the specific distances between the coil's I see no problem but rather an improvement.
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Through all of Jim's final listening / troubleshooting / optimizing phases, the parts were mounted on the actual crossover boards with all input and output leads attached to real drivers in their real cabinets. Therefore any leakage, environmental changes, etc. would be accounted for in the final as-built design. Our changes affect his outcomes and we will be reassessing actual measured performance and tweaking values as necessary.
I expect our expanded layouts to exhibit less crosstalk as well as greater thermal stability. But our target slopes and voicing will be the same as Jim's
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Measured the received Jantzen Cross coil’s, the two 0.15mH measure both 0.152 but the two 0.72mH Jantzen wax coil’s measure 0.749mH and 0.750mH :(
This will lower the crossover for the woofer about 30hz (880hz vs 850hz), my first thought is to send them back and wait another month for new one’s but maybe one of you guys have other thoughts about this?
There is also the option that I unwind them to get 0.72mH, did that before in the past but never on a foil wax coil. |
holco - unwinding is very common practice. I've never done a foil wax, but it sounds easier than a bonded coil.
I'm not following your math. 30 Hz seems like a big change. The complex effective resistance will be different with foil vs round. Can you measure the actual crosspoint change?
We always wound oversized and unwound to taste in R&D.
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tomthiel,
The coil's are completely waxed, don't know how hard the layers stick to each other, if I demolish them I lose the guarantee to get new one's.
I suspect that the woofer is 4ohm, with a 6db crossover a 0.72mH coil cross at 880Hz, 0.75mH will cross at of 850Hz, so the loss will be about 30Hz.
Yes iff I want I can measure it with REW, but I don't want to complete the crossovers with the 0.75mH coil's. |
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Holco - the woofer is 4 ohm, then incorporate any zobel network values for actual woofer impedance.
Perhaps talk to Jantzen about unwinding.
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