https://www.stereophile.com/content/thiel-cs37-loudspeaker-specifications https://www.stereophile.com/content/thiel-cs37-loudspeaker-measurements Note that the sensitivity is spec'd as: 90 dB / 2.83 V/m (not 1 Watt) the sensitivity is measured as: 90.7 dB 2.83 V/m (not 1 watt) Note that the minimum impedance is spec'd as: 2.8 Ohms the minimum impedance is measured as: 2.4 Ohms This means that the equivalent "efficiency" as when using 1 Watt will probably closer to <86 dB. Note that the only times the impedance rises above 4 Ohms (and then only in the deep bass region) it's met with rather challenging phase angles. Note that through much of the bass and lower midrange that the impedance is below 3 Ohms. Note that between 60 Hz through 20 KHz the impedance is always below 4 Ohms. Note that Thiel recommended between 100 and 600 Watts per channel. That recommendation is based upon the standard 8 Ohm amplifier rating, with the understanding that the amp would double down as needed. If one wanted to do this comfortably without amplifier strain, being able to double down to 2 Ohms would mean between 400 and 2400 Watts into 2 Ohms. Why do you think Jim Thiel used 600 Watt Krell's with the 3.7's? See Pages 16 &17 in the link below: http://www.krellonline.com/assets/support/FPB_ORIGINAL_SERIES_MANUAL_V982.pdf The more recent Thiel's are a bear to drive, limiting appropriate amplification to those well engineered products that are up to the task. The job of the amplifier is to power the speakers. Limit the search to those amplifiers that are capable of the work required, and then choose your preferred sonic signature. Anything less is compromising the work that went into developing these speakers, and the potential to fully deliver what they're capable of. Something else to consider; underpowering speakers, and especially those with 1st order cross-overs might lead to damage.
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^BTW, Class A is not a guarantee of high current. Consider SET's. And the Krell 600 Watter can deliver it in Class A. Well, it can deliver as much as the wall outlet gives it to work with. |
Thieliste, No, what’s important is that the amp is capable of delivering the power into the actual impedance load. Note how some amps will blow a fuse with just 1 channel running into such a load, never mind both. Or that sometimes an amp is not even tested into 2 Ohms. Guess why?
Some so called Class A amps decrease the percentage of Class A bias output as the power increases into lower impedances.
With most typical speakers (like the 3.7’s), as the impedance drops so does the sensitivity.
400 Watts into 2 Ohms might seem excessive, but consider that is comperable to 100 Watts into 8 Ohms.
I’m not suggesting that you need a 600 Watt high current amp (advantages aside); your room and desired listening levels will determine that. Just that Thiel’s minimum recommendation calls for close to 400 Watts into close to 2 (!) Ohms. I recommend getting an amp that is not regularly on the verge of it’s limits.
Given that an amp is capable delivering it’s power into a given impedance, it depends on the circumstances as to whether or not more power or more refinement is better. A more refined amp regularly driven into clipping would sound less
desirable and potentially be more likely to damage a speaker than a smooth running less refined higher powered amp. While unto itself Class A can be desirable, it’s just one consideration amongst many in determining the the overall quality of an amp. I’ve heard Class AB amps that sounded preferable to some Class A amps regardless of power output. And visa versa..
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Tomthiel, does the 3.5's eq do anything besides bass boost? |
Beetlemania, true but the auditory value of extended bass garners greater perceived value. Of course, if one's room can't accommodate those waves things can go south.
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Tomthiel, thankyou for your prompt and illuminating response. Were the 3.5's eq's developed and/or built in house or contracted out? Your recollections and future considerations of the CS 5's is most interesting. Perhaps my favorite Thiel model. If it weren't for the associated amplifier demands, I'd probably own a pair. I've wondered why Jim used three 8" drivers rather than say a some combination of progressively larger bass drivers, and why he chose such a low impedance? |
Thiel rebuilt both of my 3.5's midranges in the fairly recent past. |
thielrules, No, I’ve always preferred the 3.5’s. You might be thinking of “oblgny”.
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Thielrules, the drivers were damaged, so yes.
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What is the value sweet spot generation for used THIEL SCS’s?
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^I wouldn’t consider anything that drops below 4 Ohms as easy to drive. They’re not especially sensitive either. |
@tomthiel, Thanks! Looking to help a dear friend set up a system in a rather problematic room.
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@tomthiel, speakers must be placed on built in shelf.
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I would have thought the extra compensation networks needed for the older drivers would have driven the impedance down, yet the older models had easier impedances.
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^Proper driver integration and time synchronization for most Thiel’s works best at least 8’ away for a listener at typical seating height.
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Dunlavy, Duntech, Green Moutain, Meadowlark, Quad 63’s +>, jump to mind.
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AudioMachina and the original Ohm's with genuine Walsh drivers might be added to the above list of time coherent designs. |
The Thiel CS 2's grills are an extension of the baffles. |
Well, it is an older rather unique design.:-) |
tomthiel, thanks for the grill history! I'm particularly curious about the implementation of the wave guides. What were the goals for their implementation, and to that end how successful where they?
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tomthiel, did these waveguides mitigate lobing issues?
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Deciding between more smaller subs and less larger subs might best be decided by ones room. |
Jafant, erik_squires has gone on record here at Audiogon of not being a fan of Thiel’s. |
So some of those “poor man drivers” might not measure as well in isolation, but actually measure better in application
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As Oblgny has already suggested the 3.5’s work best with the 12 dB boost compensating for the natural (and superior) sealed box roll off. Allowing the speakers bass extension that only much bigger and more expensive speakers are capable of. Though perhaps without the ultimate loudness those bigger, more expensive speakers can provide. Yes, the 3.5’s don’t dig below 4 Ohms, and the impedance actually rises at the lower frequency range, which should offset to some degree that rather large 12dB drain on the amplification. Still 12 dB is considerable draw. With their shallow cross-overs, under powering this range can suck power further up into the critical mid range and even beyond. Enough power is required not only for ultimate loudness but for overall linearity and coherence.
I wonder if anyone has tried the eq options on the full core Roon platform? This might be a modern inexpensive (free?) option/upgrade to the OEM eq? It would at the very least now offer balanced connection options. Furthermore, the full core Roon platform also offers room correction, which might alllow the bass boost to be customized to one’s room rather than to a theortical anechoic model. Such room correction could even offer consideration of different room placement. As in the customary positionig the room correction could negatively effect the all important direct sound to correct the reflected sound. But....if the speakers were placed directly against the back wall, the correction would be more uniform, and proved natural bass boost requiring less amplification demands.
Of course for the pure analog crowd this might be an anathema. I am still wondering how viable it would be to convert 2 single ended stereo OEM eq’s to mono balanced units particularly for those with digital phobias.
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Small rooms can only handle so much volume before becoming overloaded, but 88 dB doesn’t really come that close to presenting the dynamic range of so much music. With appropriate amplification the 3.5’s are capable of presenting a much better presentation of this musical characteristic.
Thiel’s sensitivity ratings as presented, and as independently measured are accurate, but perhaps misleading/confusing. If one takes the actual impedance into consideration, the sensitivity decreases about 3 dB with each halving of impedance below 8 Ohms.
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If the amp could double down into 2 Ohms they would probably be braggging about. Unless it can be absolutely confirmed, I’d assume it can’t. There just aren’t that many amps that can sustain double down to 2 Ohm performance.
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@erik_squires, I am truly trying not to be petty, but, though the thread was about specific models, you posted. “Thiel’s”, not CS2’s, and you also posted “anytime”. It’s not the only time you’ve posted a less than favorable perspective on Thiel’s, As far as I’m concerned that’s fine; your entitled to your opinion. I tend to remember the opinions of those I’ve come to respect. Peace. |
As I’ve alluded to previously the sensitivity ratings can be confusing. In practice they’re really not as sensitive as they might appear at first glance.
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@tomthiel, Would you please offerer your considered opinion on my 09-17-2018 musings?
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@tomthiel, thank you for the valuable link.
Um, what I was really inquiring about was your thoughts on my 09-17-2018 post. |
I am of the thought that only infinite baffles (sealed boxes) and true transmission lines (which for full range speakers would be ginormous!) can be truly time coherent. |
Phase coherence does not guarantee time coherence.
Time coherence does guarantee phase coherence.
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Step response and square wave response are good indications of time accuracy. |
@tomthiel, wouldn’t an outboard cross-over be a simpler way to achieve the same results and reduce vibration issues at the same time?
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Tight connections are a must, but be careful, I’ve seen Thiel’s with stripped driver screw mountings due to over tightening.
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Though not currently on the market:
Dunlavy Audio Labs..
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tomthiel, see my post on 8/15/18 on page 74 of this thread. It would appear that the Bryston’s might have been better equipped to deal with the earlier Thiel’s better than the more recent ones.
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Used Krell FPB’s often times recapped, can be regularly found at near bargain prices. IMHO, great sounding amps that are truly up to the task of powering many of the Thiel’s. https://www.hifishark.com/search?q=krell+fpb I worry that we sometimes over generalize amps/speakers compatibility. Thiel CS 2’s: https://www.stereophile.com/content/thiel-cs2-loudspeaker-measurements quite a bit different than Thiel CS 5’s: https://www.stereophile.com/content/thiel-cs5-loudspeaker-measurements-0 Krell FPB 600: https://www.stereophile.com/content/krell-full-power-balanced-600-power-amplifier-measurements quite a bit different than Krell KAV 300i: https://www.stereophile.com/content/krell-kav-300i-integrated-amplifier-measurements Don’t get caught up in the hype of the gurus. Check the specs, and better yet check the independent measurements. Doing this will save a lot of wasted time and money, making one’s short list much more manageable. Then sonic preferences will be the final arbitrar. Power amps capable of driving many Thiel’s are often big and heavy. Shipping and set up can get expensive and inconvenient. True doubling down is really just theoretical. In actuality amps that tout this typically understate the power into higher impedances. In effect there is a window of operation into various loads that will determine appropriate application. Still with that said, I suspect that an amp with less high impedance power that can come closer to doubling down and down again (if necessary for the application) might have some advantages over a high powered amp that still outputs the comparable power into lower impedances, After all the extra power into higher impedances might be wasted. Of course as long as the amp is up to the job, the sonic qualities that are unmeasurable might sway one differently. Another concern I have is when some say that Jim might have recommended a particular brand of amp at a time when the Thiel products had different amplification requirements than later models. What was recommended then was for then. What came later might get very different recommendations. I strongly believe that the best course of action is to lean on the side of caution. Check the impedance of a particular Theil model and then double that down to the round impedance divisible for that particular speaker model (e.g. 2.4 Ohms to 2 Ohms) then multiply the minimum recommended power for that particular Thiel model down to that impedance (e.g. 100-400 Watts to 400-1200 Watts). This will be especially true with tube amplification. Of course different rooms and volume expectations will vary power requirements. Personally I think the old audiophile rule of thumb to double the minimum recommended power, though not hard and fast, has proven to be well time tested. As has been pointed out being stable into short term peaks is not really good enough for many Thiel models.
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^Enough power for the load at hand. |
FWIW, I preferred the sealed box CS 5’s to the 7’s.
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tomthiel, I have an updated Threshold S 500 Series II. It might be able to run CS 5’s, but I think there might be better options.
The amplifier requirements might be the only thing that’s scared me off owning the CS 5i’s.
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Sterophile never really measured any of the speakers claiming to be time coherent at the appropriate listening distances for proper driver intergration. So measurements were compromised.
I suspect some manufacturers models might have been more effected by these measurement gaffs more so than others (Green Mountain?).
Though I’ve wanted to for some time, I’ve never had a chance to hear their stuff. Roy of Green Moutain has contributed much on one of the best threads ever on Audiogon. It is very much worth seeking out. Be warned, he’s a bit critical of the Thiel coincidental drivers. Still a great read.
With that said, the Meadowlarks claimed that there “simpler” 1st order cross-overs sucked less energy from the output. IMHO, in using such simpler 1st order cross-overs they glossed over the corrections needed to correct for driver irregularities, box and baffle considerations to make for a fully true time coherent speaker system. Some of their more expensive offerings used what are now pretty much irreplaceable drivers. Some of their more moderately priced models offered some time coherence on a small footprint, furthermore some of these models were pretty easy to drive. Some even with tubes.
Some of these models offered pretty good value for those with more modest budgets. Unfortunately they disappeared with rumors of creditors chasing them. There has been some recent chatter that the brand name might be resurrected. |
As I've recently posted on another similar thread, I have my doubts about a 65 Watt Single Ended Triode being able to properly handle the 3.7's 2.5 Ohm impedance and it's accompanying phase angle. They might be better suited to their own 101dB horns (horns are not my cup of tea). At $35,000 the pair, or about three times the price of a pair of the more expensive Thiel's, I suspect they will have limited appeal to Thiel owners.
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