Thiel Owners

@vair68robert Thanks for  your input. I am going to stick with the GIK panels for now because I am low on funds and also these panels made my room sound great with the KEF LS50s. Prior to the panels the sound was awful. I understand the CS3.7 is a different beast but I am getting close to the sound I want.

I am taking the the suggestion of unsound and moved my speaker back 1 foot from the back wall. This is the closet I have had any speaker in this room. Still trying to figure out if I like that positioning. Though with DRC it will not matter.

I am playing Santana's Caranvanserai SACD and it sounds pretty good. Thought last night when I played it on my headphones I was wowed and thought I need to hear this again on the CS3.7 in the morning. It is not as great on the speakers and I think it is not the room this time, Ii is the amp. This is an album where some power is required out of the amp. There is a lot of percussion on this album.

I got feedback from the DRC engineer this morning after I sent him my 2 preliminary measurement files. He plotted the measurement on a graph and the lines were very close from the 2 different days. The measurement with the desk in the room actually had a little better base. Though I liked the sound without the desk.  I will be sending more measurements today to get him going on the Convolution file generation for my room.

^ I would think that the very close (right up against the wall) would really only work with DSP. Without DSP I would think the opposite would be true, Though bass reinforcement  and less strain on the amp might be the case against the wall with or without DSP.

Keep the time domain in mind, especially for phase coherent speakers. On and off axis radiation patterns are different as the frequency rises. The speaker is balanced into an "average" environment with assumptions made as to where the front and side walls "might likely" be. Those assumptions never include placement near a wall. Perhaps you can unscramble the changes with DSP, but the differences with placement will be significant.

^I agree, when there is no DSP. But, that’s the beauty of DSP, it has the potential to remove those “assumptions” and replace them with real time and space measurements. Problems arise when the those measurements correct the relatively small in volume (not sound pressure) though more important primary direct sound as though they were the larger in volume (again not sound pressure) though less important reflected and distorted room sound, creating a weird primary direct sound. By placing the initial primary source of the sound close to the room boundaries they are more similar and there is less difference between the two. Flush mounting would be ideal. Due to the inherent bass reinforcement, it can also relieve the amplification of some burden, that might or might not be exacerbated by the DSP processing.

yyzsantabarbara

2nd- Santana 'Caravanserai' is an excellent SACD for testing one's system. There are 2 different releases on this title. I believe that I own the 1st pressing. MoFi is the re-issue.

Happy Listening!

Some important news was found out from my DRC measurement steps (first step actually).

I want to clarify a point about the slight harshness I was hearing on the CS3.7 top end. I was saying it was not as smooth as the KEF LS50.

The measurements showed that right speakers Coax driver is out of phase with the left speaker Coax (maybe one can say the opposite). There is some harshness on the frequency response due to this miss-wiring. I guess my hearing is good.

Prior to the sale I knew that the previous owner got a new Coax driver from Rob G and soldered the Coax wiring himself. He was a little worried about the wiring since there was a 2 week delay with shipping the driver to Rob and getting the new one. Anyways, the previous owner and I are working to get this fixed, should be an easy job. I will give Rob a call tomorrow to find out the specifics of the job.

So the DRC work is halted until this out of phase issue is resolved. I am going to find some electronics guy/gal to do the solder, since I am a newbie on that and I want it perfect.

BTW - the engineer up in Canada, Mitch Barnett, used to owned Thiel CS3.7 and he loved them.

@jafant My pressing of the SACD is from SME records. I now have my SACD player less than a foot from my seating position. Makes things easy. Getting real lazy with age.

SME is the 1st pressing (1999) 

Happy Listening!

I called Rob Gillum about the COAX installation know what needs to be done to resolve the out-of-phase issue. I have decided to use the services of a local audio store in Santa Barbara. They will send a repair tech to my home next Tuesday to do the soldering. Learning a lot of technical stuff with this hiccup.

I decided to move the Thiel CS3.7 to a new position. I now have them 2 feet from the front wall and about 2 feet from the side wall. The speakers are now closer together about 6 feet apart. The sound now is better than any other prior placement. Even with DRC I will keep this positioning, mainly because I have 3 out of 4 sources that will not use DRC. Only my digital streaming via ROON will use DRC (if I like it).

So next week is when the interesting stuff happens. Enjoying the out-of-phase tunes until then.

I also bought an CS3.7 Outrigger for the speaker feet. My 4 year old first words when he saw the CS3.7 in my office was "I want to climb it".

yyzsantabarbara

keep us posted on the Coax fix.

Happy Listening!

yysantabarbara

Nice catch or should I say good ears ,
but strange because the coax speakers polarity are clearly marked
with the red and black wires going from the solder pad to the speaker ,
and  if the crossover is like the 2.7 the negative / black wires from the tweeter and midrange  are soldered together .

I hope that wrong wiring is your problem .
Good luck and hope it's not to big of a repair bill .

Yyz - the definitive test is to make a momentary connection from a 6 volt lantern battery (or other 6 volt DC source) to the XO inputs. All drivers should move forward. You can readily see the woofer and midrange move, but may have to feel the tweeter. And Thiel uses silver solder which has a higher melt temp than utility solder. A 140 watt gun is just right.

Thanks everyone for the great info provided here. It has made this problem pretty easy and fast to resolve. I have a speaker repair tech from the local high end audio store coming to my home next Tuesday. The cost is not much for 1 hour work and the speaker seller has volunteered to cover the expense. The estimated cost is pretty low (so far) so not concerned. I will have everything ready to just unsolder and re-solder.

The speaker tech is aware of the battery test though the sound engineer in Canada told me to send him another set of measurements and he will tell me if it is setup correctly. I will see how experienced the repair guy is before I figure out which way to test it.

I received the following feedback from Rob Gillium today about the wiring.

The CS3.7 is a three way speaker, with a Passive Radiator. Each crossover section has a pair of output wires. There are three pairs. One pair to the woofer, one pair to the midrange (coax), and one pair to the tweeter (coax). The coaxial driver is a two driver combination, (midrange and tweeter). Each driver has a pair of wires. The white output wire is positive and should be connected to the red terminal of each driver. The black wire is connected to each unmarked. terminal of the drivers. These wires must be connected in this fashion, to be in phase with each other. If one of the drivers are connected out of phase (reverse polarity), then it will cancel the output from the other driver, thus rendering poor sonic quality. It is very important to connect the midrange pair to the midrange, and the tweeter pair to the tweeter. If these are connected wrong, then the tweeter will see the mid frequencies, and be destroyed in most cases.

I was also speaking with a CS3.7 owner in Brazil who is active on the ASR forum and he thought the Coda #8 V1 would be what he would select from the #8 options. However, he did mention that Purifi is going to come out with a new module that will have similar specs as the NC1200. He is waiting on that before any new amp purchase. He suggested I do the same.

I have a feeling the current Purifi module sounds very similar o the AHB2. A future module with the the same sound but NC1200 power specs would be great for the CS3.7.

I should say again how happy I am that I payed attention to TomThiel’s post about positioning. I was initially trying to get max space between the speakers with low side and later low front wall spacing. Now with the speakers around 2 feet from the front wall, 2 feet from the side, and only 6 feet in-between, the sound is really good, the best so far.

Yes, the side and front wall reflections are quite important. Your room is quite narrow, since the polar pattern of the CS3.7 is quite omnidirectional. Can you try putting them on the long wall?

I cannot play with the placement other than these minor movements. I bought the CS3.7 on the assumption that if it did not work in the office. I could eventually move them downstairs to the much larger living room. The living room is my sons play room at the moment.

However, the placement that I just did is great. Given the circumstances of this room I am extremely happy about the sound, except for that harshness. which will be resolved on Tuesday.

I will say to prospective CS3.7 buyers that the speaker will play in a acoustically treated room small room, see my Virtual System on A'gon. I understand that I am not getting the very best sound out of the CS3.7 but, what I am getting is very good. 

Reading everything on the web on this room size issue made me think it would not work. I am shocked actually that this is working so well and I am not getting overwhelmed with bass. I still have the DRC implementation that I can bring to the table to potentially make things even better.

unsound & thielrules - about individual amps. I’ve been comparing configurations these past few days and conclude that it’s very murky water. I have matched pairs of Adcom GFA-555 mkII, Classe DR9 and Benchmark AFB-2s. The power is similar, but the clipping characteristics are different. Even with using same source, preamp, cables and speakers, the amps’ characters change when stereo or bridged and how hard they are pushed. All things considered, it would be hard to make any ’best recommendation’. I agree with unsound’s thought about ’same amp’ for bass and treble. Gain matching is very important as well as overload characteristics.

At this point what I can say for sure is that among my amp stable, the AHB-2 is the cleanest, clearest, most harmonically convincing. To my previous comment about its possible bass ’deficiency’: I suspect it is outputting most accurately, even though other amps might be more appealing. After speaking with John Siau of Benchmark and poring over test results of all the amps, I’m convinced that the AHB-2 stays extremely clean (until it clips), whereas other amps delay bass frequencies which is experienced as hanging longer in time, and produce harmonic (distortion) addenda which is experienced as more amplitude. Combining time delay and more harmonics produce bigger bass. But, the AHB-2 bass is so clean and articulate with considerably more inner harmonic detail. The problem still remains that it admittedly produces "less" apparent bass than other amps, so the producers’ intent may have more bass than the listeners’ experience with the AHB-2.

My preferred setup is running a pair of AHB-2s in bridged mono, each driving a full-range speaker with 3 separate, identical cable runs (or two runs that combine midrange and tweeter feeds. I rigged some 6’ and 12’ runs and cutting the runs to half length increases damping factor by 2 and tightens up the bass that was loosened by bridging. If I could afford to splurge, I would use 4 AHB-2s, all bridged. One for each channel’s woofer and the other for the mid-tweeter. But, I don’t feel the need, a bridged pair doesn’t clip in my situation, and unlike normal amps, the AHB-2 distortion stays near zero into any drivable impedance until it clips. JS says that impedance limit is around 2 ohms, so some Thiel models are in jeopardy. But I haven’t experienced it with my 2.2 and 3.5 testing. I wish Jim had kept his loads above 4 ohms nominal, 3 ohms minimum to stay out of trouble.

 I have no doubt that identical individual amps for each driver would be ideal, especially when one considers the potential of DSP when so configured.  I would  have preferred 4 Ohm minimum loads. The difference is not as insignificant as might first appear, particularly for those that might prefer tube amplification (which doesn’t include myself). That would also allow consumers to use standard ratings and measurements without prevailing doubts.

Unsound - I agree to wanting 4 ohms minimum which would roughly double the impedance of many Thiel models, making them far easier loads to drive with lower amplifier distortion and fewer cable interactions. Jim committed to underhung voicecoils as a way to reduce motor distortion by an order of magnitude. Walter Kling developed the methods and machines to make those drivers. He shared that industry driver manufacturers considered them nearly impossible to make and therefore expensive and ill-advised. Jim and Walter took that as a challenge and took it on and never looked back. One of the downsides includes the coils being only a few winds long (short?) x 4 layers thick, which is precarious geometry indeed. More turns would raise impedance, but also add mass and mechanical reactance in a system short on gap flux due to the thick coil. The feasible balance point seems to have been where he landed. He wasn't really out to make our lives difficult driving them, it just worked out that way.

@yyzsantabarbara1  I bought 3.7s in 2012 and had kids in 2013 and 2014.  Audio dropped way down on my priority list and I had them in several far from ideal spots.  I had them right next to each other for a while and they sounded great.  You don't get much in the way of imaging but otherwise great.  I had them nearfield for a while on each side of my desk with my head a couple of feet in front of them but way off axis.  Still great.  I worked from home for a few years and I was always amazed at how good they sounded in this far from ideal situation.  I couldn't believe how well the image held together.  From a placement standpoint the coax is magic.

From a placement standpoint the coax is magic.

I agree. I have had a few speakers with the tweeter and mid on the same driver unit and it has always made placement much easier. I am slightly off center in my seating. With my KEF LS50's (also a similar type of driver) I had to make an adjustment on my preamp's balance to give the far speaker a bit more juice. With the CS3.7 I set the balance to 0 and it sounds great. The sweet spot is bigger than most speakers. The KEF Blade is also like that with a big sweet spot.

Sounds like you are a music fan. When my kid was under 2 years my office/audio room was in a laundry room. I would work and listen while a washer and or dryer was going full blast next to me usually washing kids stuff. Still enjoyed music.

Unsound and Tom. As you know the 3.5 individual drivers are all above the 5 ohm across the whole range and combined stay above 4 ohms. Makes it very suitable for tri amping or bi amping. I would guess that bi amping the bass and mid-tweeter with one amp would be better then using the amp in serial configuration for all drivers. Is that consistent with your experience? 

Happy Friday! All

Thielrules - it all depends. A very big deal is running out of power. The Adcom and Benchmark have overload LEDs. Listening at 95dB peaks at listening position, the Benchmark overloads consistently in stereo with one amp channel driving the woofer and the other the mid-tweeter. The bass amp can be bridged and its input sensitivity reduced to match the stereo upper amp. The upper stereo amp then becomes the overload limit, so it also must be used in bridged mono. Clipping is unacceptable. The Adcom at twice the power is better, but marginal on the mid-tweeter. It has no input sensitivity selector and therefore in stereo it cannot be easily gain-matched to the bridged woofer. So no go for tri-amping. Classe DR9 has similar power to AHB, so I assume it clips even though it doesn’t give LED proof. If you had 4 amps and could dedicate one to each woofer and one each to the two mid-tweeters, that is theoretically better than a single bridged amp to all three drivers, at twice the amp/cable expense. I am personally at peace with a Bridged Benchmark driving each channel with 3 separate cable runs or two runs: one to the woofer and another to the mid-tweeter.

To your question of best configuration - Because low impedance loads cause higher distortion in normal (non AHB) class A/B amps, I would prefer a stereo amp with one channel for the woofer and the other for the mid-tweeter. Those amps would need to be a few hundred watts minimum per channel into 4 ohms in order to stay clean. My amps in my space don’t deliver the goods satisfactorily in stereo mode.

Let’s do some history. As you know, the CS3 was set-up for bi-amping / bi-wiring. It separated the tweeter from the rest of the signal because the equalizer boosted the bass which included contribution from both the midrange and woofer, so they couldn’t be segregated to different amps. Audible improvement was gained by separating the tweeter. But the preponderance of users chose small SET or tube amps for the tweeter with no consistent way to gain-match the low frequency amp. Solving those variables would have required a different kind of dealer. Jim assessed that we didn’t have that expertise in the field to his satisfaction and removed the bi-amp /bi-wire option.

The scene is different today in that remaining Thiel users are likely to commit to getting it right or staying on the sidelines. It is tricky business, especially in the absence of clipping lights and with uncompressed and/or otherwise very dynamic music. Underpowering makes distortion and distortion fries drivers. Be careful.

tomthiel

Thank You for the history lesson. Keep up the excellent work via hot rod garage and studio. I can tell that you have made great strides while having fun.

Happy Listening!

JA - what a trip indeed. Circumstances have prevented progress in ways that many here assumed or wished for. I’m not yet discouraged; and I’m stirring the pot every day. My personal interest drives me to decipher some of the mysteries of Thiel and the idiosyncracies of its product performance. As you know, I have speculated that phase coherence allows the audio-brain to scrutinize sound differently than non phase coherent sound - as I formerly have written here. I beleve that, but many elements don’t neatly fit into that narrative, including the opinions of knowledgeable practitioners to the contrary. My search and questoning have taken unexpected turns.
An early assumption of low-hanging fruit was crossover component upgrade. Indeed good results were gotten there; similarly hookup wire and softening the wave launch surfaces on the baffle. But a derail occurred serendipitiously on a flight of fancy when I fantasized with an audio friend about some aha moments during early product development experiences in the 1970s. We identified the let-down when the ’hanging sculpture’ of the free-air crossover-in-development was nailed down and put in the cabinet. Magic went missing. Long story shortened, we re-created a bird’s nest crossover hanging in space. And, guess what - magic.

I have developed and tested some hypotheses and solutions and identified some obscure aspects of performance that migrate the musical experience from somewhat canned to substantially transparent. A relevant result is how ancillary equipment interacts with my speakers under test. Thiel fans have spent enormous time, effort and funds finding source equipment that works. And when it works, it works well. Shortened story: the outboard crossover has opened doors not only to better music, but to finding solutions to some pretty subtle problems, including broadening the range of acceptable drive components while increasing the level of detail, transparency and 'rightness'.

Anyhow, in moments of nostalgia for a company history that never was, I wonder about what we might have built if we had asked these questions and found these solutions in parallel with Jim’s relentless progress in the areas of his interest and expertise - where his innate comprehension of physics met his unique engineering ability to convert his best ideas into uniquely satisfying products. But, there is always more potential, isn’t there. What a trip finding some buried gems hiding in plain view within the platform he created.

@tomthiel, I wish I could share your faith in Thiel users getting amplification right. It seems that many seem to choose to ignore the basics. It’s not entirely their fault. I’ve seen different dealers offering what to me where incredulous demonstrations. Such as powering CS 3.6’s with 20  Watt intergrateds or CS 5’s with 50 Watt amps all the while resorting to their cheezy salesmanship gimmicks of grinning with crossed arms, nodding their heads up and down, tapping their foot,...all at barely audible listening levels. They were none too happy when I increased the volume to much, much less than typical listening levels. They would then lower the volume some and say that at these volumes the amps were sufficient, all the while the sound was of crunching distortion.
 Your points about radiation patterns and room placement were spot on. And let me clarify that even with DSP it would be preferable to work with a speaker that already was designed for a specific predictable placement rather than against it. Even if we’re not quite there yet, I firmly believe that DSP is the future. Though we may have to abandon previous notions to embrace the advantages of a new paradigm.
 The shared insights as to why the Thiel’s tend have low impedances was most interesting. In that there are still a few amplifiers to choose from that are up to the task justifies the gains in cohesion, ease of placement, and especially reducing lobbing effects.  I am continually impressed by the latest flat co-axils.
 Your comments about free standing cross-overs was most interesting. I seem to recall reading an article where Richard Vandersteen had the same “AhHa” moment with similar circumstances of free standing first order cross-overs. I never gave it much thought before. Perhaps vibrations, EMI, RFI, all, some combination, or none of the above? I’d be most interested in following your research on the matter. I’m still curious about your research on baffle reflections as well. Thanks so much for maintaining the research progress of our favored Thiel’s.
 

Unsound -
As you say, sufficient power is an absolute requirement. I may be naive, but I'm thinking that with good used equipment available at bargain prices, education would be fruitful because many folks could actually afford good to great solutions.
In addition to EMI and RFI from the interactions between the crossovers and the drivers, there is the proximity to metal driver frames and pressure fluxuations. A big deal is that cabinet vibrations necessitate every component being glued down to avoid microphonic and fatigue vibration. Plus the cabinet is a closed cavity, so heat generated by the crossover losses as well as the driver motors, wh heats up everything, changing the component values and circuit functions. It's not subtle. By outboarding I can dump crossover heat at the crossover and driver heat via heat sinks and thermal malpractice and compression are greatly reduced. each component can be mounted for maximum cooling.

The baffle stuff is quite intriguing - newly developed plate resonators to quiet and organize the launch waves. Coupling of driver motion to proper air waves is less than trivial as well is the chaos of early diffraction. Thiel paid lots of attention to that, but more attention is fruitful.

Here's an aside. I can play a woofer in a cabinet adjacent to its mate with the mid-tweeter. Same feed signal. Taking the woofer-induced vibrations out of the (upper) cabinet cleans up the high end considerably. Imagine that. I thought the CS2.2 cabinet was quite quiet, and it is by comparative standards. But better is better. I can remove the cabinet top and bottom to doctor the cabinet walls, newly accessible from taking the crossover outboard. Two versions under development. Underslung Crossover places the 3D network in a vibration-insulated and ventilated chamber under the cabinet while the Outboard Crossover version puts it in a free-standing enclosure about 3' behind and connected by an umbilical to the drivers.

To your point about the flat coaxes. Jim wanted coaxes from the very beginning for their solutions to placement and lobing problems. It took till the SCS in the late 80s to execute the coax and gradually get the outer cone more and more shallow to minimize the squak-effect. The flat-wave solves so many issues.

@tomthiel, Yes, you would think with quality that originally went into them, that some of the amplifiers on the used market would be especially appreciated at their now discounted prices.  Too many are caught up in marketing of the “latest and greatest” gear getting all the most recent attention. While there has been some improvement in some specific parts, these parts are not necessarily exponentially better, and many can be retrofitted to older gear. Some of the newer amps don’t actually perform as well as the older stuff with the speakers at hand. Interestingly, some of the more recent amps are actually based on even older circuit designs. Which in itself might or might not be a good thing. The perception of the suitability is sometimes different than the reality. The physics hasn’t changed. Not being mindful of the criterion used to make the lists, or how the maker of the lists keeps a revenue stream going; it’s as though if it’s not currently on a Class A rating list it can’t be any good.
I hope all your super good work(!) comes to fruition for us Thiel lovers soon!

I want update my journey with the Thiel CS3.7 now that some changes were made.

1) A speaker repair tech came to my house today and re-soldered the crossover wires to the tweeter and midrange of my right speaker. They were wired out-of-phase during a prior DIY OEM COAX replacement. The speaker seller has volunteered to pay for todays repair.

2) I discovered a damaged screw thread on the left speaker frame. Rob Gillum pointed me to a toolkit to repair that. It is being shipped to me now ($44). The original speaker dealer seems to have gone torque crazy with the driver screws.

3) I will sandpaper and lacquer the speaker because this speaker is never leaving. Rob Gillum gave me instructions on best approaches for that.

4) I ordered the outriggers from Rob G. for the day that my 4 year old son decides to climb the speaker.

After #1 was done today the speaker sound just opened up. The harshness is gone and the soundstage is huge the imaging is better. Just like I remembered 12 years ago at the store demo. I think it actually sounds better today on my all Benchmark stack than the all Classe gear of the demo.

Getting to that Benchmark stack. I have been disparaging the AHB2 Stereo amp with the CS3.7. Saying it sounds lean and not dynamic. I was thinking in my small room 194 watts at 4 Ohms should have worked. The amp also goes down to 2 Ohms but I do not remember the numbers for that. However, the sound was not that good wherever I positioned the speakers. I think I said on a scale of 100 it felt like a 75, even less on dynamic music. Today, after the out-of-phase fix the sound is powerful, dynamic and glorious. I would say a 95 out of 100 now. The room is still there so not a 100.

I am kind of curious still about the CODA #8 amp with the CS3.7 but I do know that the AHB2 will never leave this system. I caught a lucky break by not selling it a few days ago to fund the purchase of the #8.

So in a small room, see my Virtual Systems, the Thiel CS3.7 + an all Benchmark stack (with a single AHB stereo amp) sounds amazing.

I will explore the DRC implementation tomorrow now that the drivers are working right.

BTW - I was just thinking that reason that the it was easy for me to hear the out-of-phase problem was because of the revealing nature of the Benchmark gear.

I also now feel that for my room the Luxman m900u and the CODA #16 would also be viable alternative amps. I do not need the massive amounts of power at 2 Ohms for this room.

@jafant I ordered the Mofi version of Santana’s Caravanserai. My current SME version now sounds better on the CS3.7 than on my Meze Empy headphones. It sounded better on the headphones prior to my speaker repair today.

Looking forward to the MoFi version since you say it is the better version.

yyzsantabarbara

Thank You for the update. After a few listens to the MoFi- let me know how the 2 discs compare in sound quality.

Happy Listening!

@xyzsantabarbara, Yes, for a small room you can get away with less power. But, it’s at 2 Ohms where you need it. The 3.7’s don’t just visit that impedance, that’s where they live. What you don’t need is massive amounts of power at 8 Ohms; they don’t go there. Keep in mind that 2 Ohms loads are about 1/4 as sensitive as 8 Ohm loads. It’s all about what the amp can do in the actual working conditions at hand, all else is moot.

@unsound I hear you. I have very good sound now, I cannot stop listening. However, I think there is still another level I can get with more power. I sent Rory Rail at Benchmark an email asking about a second AHB2. I know 2 AHB2 and the CS3.7 has been discounted on this thread but I wanted to get confirmation from Benchmark before I close the door on that.

I forgot how fast the C3.7 sounds. Just an incredible speaker. I am incredibly happy I went with the CS3.7 over the newer speakers I had demoed and liked a lot. I love the CS3.7 sound, it just feels correct.

I did some online research and I found out that 1 AHB2 in stereo puts out 259 watts into 2 Ohms.  That is not too bad.

https://benchmarkmedia.com/blogs/application_notes/speaker-efficiency-and-amplifier-power

Near the bottom in the section titled, " AHB2 OUTPUT VOLTAGE AND OUTPUT POWER"

They do not list any specs for mono mode at 2 Ohms.

I was not specifically pointing at the Benchmark. The Benchmark's are a somewhat unique, but perhaps not enough to be a clear exception. Most amps when bridged into mono don't like working into lower impedances. Benchmark does sort of dance around a 4 Ohm nominal recommendation when used in mono configuration. The 3.7's despite claims to the contrary are really below a 4 Ohm nominal load.  When taking the reduced sensitivity of 2 Ohms into consideration, it's 259 Watts 2 Ohm rating would comparable to about 65 Watts of power into 8 Ohms. That might be enough in a small room, but if you push it, it might lead to driver damaging clipping. Those 2 Ohm power ratings can often misleadingly appear to be providing tremendous power, but when one considers the reduced sensitivity it's really not all that much to work with.

Great info thanks. 

I will likely hear back from Benchmark that mono is not doable with the CS3.7. Your comments give even better reason to look at other options.

@yyzsantabarbara , see tomthiel's recent comments on this very subject.

@unsound Yes, I am paraphrasing his comments in my email with Benchmark. I am just crossing my T's and dotting my I's before I close the door on the mono AHB2.

I have been looking around the net for alternative amps, if 2 x AHB2 is a non-starter, I keep coming back to the CODA #8.

I am trying to figure out why people have recommended me to get more Class A first watts instead of more Class AB watts at 2 Ohms with regards to the CODA #8. I guess I can always circle back and discuss again with these folks.

@yyzsantabarbara  IMO in your small room even a used Gryphon Diablo 120 would be a significant upgrade over your AHB2.In terms of musicality Gryphon is in another league IMO.Just my 2 cents.I myself am waiting until a used Diablo 300 pops out to jump on it and will therefore get 3.7s.Best to you.

Thanks for the feedback. I am not sure what musicality means but I do know that gear like the Luxman m900u have a softer presentation of the sound. Likely like the Gryphon but with the Gryphon having more slam. The USA distributer of Gryphon is local to me. I am sure I will hear their gear next time there is a big show in my area.

I am participating in a HPA4 preamp/headphone amp thread on another forum and someone there is saying the same thing about the HPA4 which sounds exactly like the AHB2. Too neutral no magic, etc... It is just a matter of taste. 

Now I loved the sound of the Luxman m900u. I also love the totally different sound of the AHB2. Both are amazing at what they do. The CODA #8 or #16 is described as being similar to the Luxman but with more slam. The CODA is a ton cheaper in the USA with a 10 year warranty. So that is why I have mentioned the CODA so often. I can also get it customized with some SpeakON speaker connector to make my amp switching task with an AHB2 a breeze. 

The AHB2 will always be part of my collection. It is a brilliant amp. Some may not appreciate its naked sound but I love it. It sounded the very best today after the out of phase fix I mentioned previously. I wonder if I would have even noticed that problem with another amp?

yyzsantabarbara

I have found that the best approach to a Thiel loudspeaker, allow your ears to guide you. Specs are helpful to a degree. Specs are not the only aural factor up for consideration, IMO. I believe that we can all agree on an amp that doubles down in power rating from 8 to 4 ohms. The rest is a matter of taste. 2020 has been a banner year for Integrated amp(s).
Until last year, I would have never given the notion, a second thought. 
My AYRE integrated is a killer and musical as separates for more money.

Happy Listening!

@yyzsantabarbara  By musicality i mean organic, meat on the bone , engaging, the opposite of cold, thin and sibilant.This is the type of amp you need for 3.7s to sing.I would rather get the smallest Gryphon amp as opposed to Krell or Bryston for instance.If you live near the US Gryphon distributor he would probably glad to invite you for an audition of the Diablo 120 at his place.
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@Jafant, sure an amp that doubles down from 8 to 4 Ohms is satisfactory enough for a speaker that operates within that load. For a speaker that operates below that, it’s a matter of physics and the necessary electrical engineering to navigate it. After that it’s a matter or taste. I’m not out to burst your bubble, after all the point of all of this is to seek joy. You believe what you want, spend your money as you see fit, but it’s hard to argue with the facts.

@thieliste, Depending on the specific models of course, I think the Krells are closer to the Gryphons than the Brystons. On the used market here in the US one could can get Krell separates that perform closer to the Gryphon separates for less than the price of a Gryphon integrated. Too often in this hobby brands become victims of their own previous success's. They lose the mystique of their elusive exclusivity, and undeservingly become shunned upon by the snobs.

@yyz,Glad to hear you are enjoying the 3.7s with the all Benchmark setup -- same as I have. Yes, the sound is wide open and glorious. I've never had the AHB2 clip light go on in my 18 x 18 room, even with full-on orchestral music. It's just not an issue running a single amp in stereo mode.

Great feedback. Some updates.

1) Rory at Benchmark forwarded my email to John Siau, the amp designer. He has the Thiel CS3.7 specs from Stereophile measurements linked in the email. He is out now but I hope to hear from him once he gets back.

2) I am trying to get my speaker measured again today to send to the Audio Engineer in Canada for the DRC. A lot of crazy stuff happening in the home front (like flooding, no babysitter, etc..) so I need to sneak in some time.

I will work with a dealer if I get the CODA as an alternative second amp. This dealer also has Krell. He said the new Krell XD is somewhat like the CODA but even warmer. Though for the cost differential it is a no brainer to get the CODA. As I mentioned before the power specs on the specific model I am referencing #8 is perfect for the CS3.7. There are 3 versions to choose from. This is set at the factory.

• 150 watt @ 8 Ohm (first 18 in Class A) | 300 @ 4  | 600 @ 2
• 250 watt @ 8 Ohm (first 12 in Class A) | 500 @ 4 | 1000 @ 2
  
• 350 watt @ 8 Ohm (first 8 in Class A) | 700 @ 4 | 1400 @ 2
  

The cost is under $6K with 10 year warranty. Another great American company like Benchmark and Thiel. CODA can also customize the speaker outputs for me, to use SpeakON so that flipping my SpeakON ended speaker cables would be a breeze. I would never need to unplug from the speaker end.

@tmsrdg Thanks for the follow-up. I thought of your earlier posts on the AHB2 with the CS3.7 and did decided not sell to fund a new CODA #8 because how much you liked it. I figured something was not right on my side and wanted to wait until at least the DRC work. Now it is really a great sound even without DRC. It is shocking actually the difference since the wring was fixed. I now know I have 1 of the 2 best speakers I have ever heard.

@thieliste
There is the meat to the sound of the all Benchmark stack. It is not the warmish meaty+ Luxman sound but a great sound nevertheless. Not saying one is better than the other. I love both.

I have been in the demo rooms of many show with Philip Hanlon of Luxman and now Gryphon fame. I do not think I need to spend at his cost of gear to get the best out of the CS3.7 but until I demo the Gryphon this is an assumption. I must say that I am not a fan of "fat on the meat" sound, just "lean meat on the bone" is fine. Luxman was one of the few that I liked that was tubey and warm sounding, but I did not want to cross that limit of meaty sound. Different strokes for different folks.

BTW - In December The Absolute Sound will do a review of the gear I have, maybe minus the AHB2. Which will be good for me to read how other amps work with my stack. 

@yyzsantabarbara, The latest Krell’s unlike most of the earlier Dan D’Agostino era separates models are no longer spec’d into 2 Ohms. The newest Krell’s like the original models have returned to forced fan cooling. Something I personally don’t care for. I’ll hazard an assumption that at 2 Ohms those Coda Class A specs can be reduced to 25% of their 8 Ohm Class A rating.

@yyzsantabarbara  I completely agree about Luxman being kind of too warmish and meaty.I 've heard the the M900-C900 combo several times and was never blowned away.Gryphon integrated are much more fun, it's very dynamic, transparent, fast, huge slam and still organic and never muddy.It will not cost you anything to just go for an audition and see if you like the house sound and compare to the gear you already know.

@thieliste I appreciate your feedback. I will give it a try since it is so easy for me being local. I do not want an integrated since my system positioning is setup for separates. I wanted a cleared path from my speakers to my ears. I am very happy with what I have done to facilitate this in a small room. I will check out their dedicated amps instead.

I just did some quick looking at the Gryphon amps and they seem like competitors to the USA made CODA #16.

I am currently listening to Santana’s - The Woodstock Experience and while it sounds very good and I am bopping along. I would like more power to really feel that percussion.

@unsound you are correct about the 25% reduction at 2 Ohms. I asked them since you mentioned it before. I am not a big Class A guy. Whatever gets me to great sound will work, Class A, AB, D, etc..

@yyzsantabarbara  Ok well if you are not considering integrated forget about Gryphon, the separates are too expensive for Thiel owners IMO.Only Diablo 120 or 300 is worth considering for CS 3.7s owners.

This journey I am talking with the CS3.7 is hitting rough patch after rough patch. It is not really bugging me though, a little interesting actually. Learning a ton of stuff about audio. My background is as an expert listener of music. :)

Today I did the REW software measurements of the 2 speakers. The new issue is that the Sound Pressure Level graph of my LEFT and RIGHT speaker are not identical. There is sufficient divergence between the L and R to indicate that something is wrong. This divergence occurs at 1K level. I got this feedback from the Audio Engineer who analyzed the data.

So I am going to learn how to interpret the REW software correctly and measure my KEF LS50s myself to eliminate the very new Benchmark gear as the culprit. I am almost 100% certain this less than 6 month old brand new Benchmark gear is flawless.

I have an idea what the issue is but will not speculate here until I speak with Rob Gillum tomorrow morning. If my hypothesis is correct it will cost me some funds to fix it.

I should note that both COAX drivers are in phase now and to my ears the system sounds great. However, I cannot move forward with the DRC until the SPL graphs are almost identical.

BTW - I was just playing The Boy’s Doin’ It - Hugh Masekela. That sounds so good on the CS3.7