Couldn't resist being post 13,001.
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@dickieboy, I’m not sure where the “many” are that you are hearing are suggesting that the CS 3.5’s have a sub 4 Ohm load. Do keep in mind that the CS 3.5’s eq can demand up to an extra 12 dB of draw from the partnering amplification. While Jim Thiel most cleverly used the inherent box resonance impedance rise that coincidentally occurs at just where the eq is most demanding to somewhat mitigate the draw, it still puts quite a bit of extra demand on the partnering amplification. Jim Thiel would have recommended at least 80-100 Watts (depending on vintage) into 4 Ohms for the CS 3.5’s. |
Jafant My system is VPI HW19 MkIII with Premier FT3 arm and Grado Sonata low output, ARC CD3, ARC SP9 MkiII, ARC Classic 60 feeding the CS 3.5's. I know you're a cable guy, so I replaced initial Audio quest speaker cable and FMS Blue interconnects with MIT MH 750 and MI 330 which was a classic combo which had great bass and resolution while keeping the top end smooth. I more recently upgraded to all MorrowA5 interconnects and SP6 speaker cable and Morrow power cords. Nice improvement in all parameters while being very natural sounding. Unlike many on Audiogon, I've had this setup since about 1988 with the cable being the only real change. I've recently purchased a townhome with smaller space and (horrors!!!) I've downsized from the 3.5's to PMC Twenty5.35i's, These have worked out in the context of my existing system and space. My black ash, one owner, all original and updated CS 3.5's are now at Holt Hill Audio to be consigned if anyone on this thread is interested. Brian Salazar has not put them up on his website yet, but I doubt you'll find a better pair and with a known history. While the PMC's are working well for me, it's like parting with an old friend! Unsound I was referring to how often people generalize and apply the "big watts, tough to drive" to all Thiels, as it's not really true of the 3.5. That's all.
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@unsound, turns out you were right when stating that
Even though rated to be 'stable for musical transients' at 2 ohms, the PS Audio GCA 250 does not seem to really enjoy powering the Thiel 2.4. It does offer really incredible dynamics and microdetail, but it also seems to exaggerate highs when asked to reproduce something like a piano sonata at somewhat higher volumes. I'll search the thread for other amplifier suggestions (: Anyone who has good experience with amps that excel at reproducing orchestral dynamics on the 2.4, feel free to chime in!
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I've been very happy driving my CS 2.4 speakers with a Coda CSiB v1 integrated amp. The Coda doubles down as you halve the impedance. The CSiB is for all intents and purposes a CODA 8 basic amp with an integrated line stage. Prior to the Coda I had a Bryston 3Bst. The 3Bst together with a Bryston preamp did a nice job of it, but the Coda was a big step up. As per my handle, I'm a jazz guy, but an audiophile buddy who is into Classical gave my rig a test run and was very impressed with it.
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@dickieboy , Ah, that's a bit different. And with that I agree. Even here on Audiogon it's often over generalized that all Thiels are demanding of amplifiers. The CS 1's 1.2's, 2's, 3's and 3.5's all had impedances over 4 Ohms (though the CS 3's and 3.5's did have the eq demands as well). Look at this rather benign impedance plot: |
@lars888888 , I suggest limiting your search for amps that are actually spec'd to 2 Ohm loads. If an amp is truly capable, the manufactures are likey to brag about it. I'd avoid amps from manufactures that rely on ancedotal marketing. If the amp is truly up to the task, let them put it in writting. Some (but not all !) amps from Krell, Levinson, and Threshold amongst a handful of others could qualify. If looking at some older models; I'd look for amplifiers that have been recently recapped by the manufacturer or manufacturer endorsed tech. These amps are typically heavy and costly to ship so having had this done recently could be prudent. Power amps tend to work better than integrateds for speakers such as the CS 2.4's, . As Intergrateds often are less adept at lower impedances and/or are less richly biased than the power amp offerings |
Regarding amps: In addditon to my hotrodded learning labs of Classé DR9s and Adcom GFA555s, my reference amp is the Benchmark AHB2. A single stereo amp may not have the oomph you need/want, but in bridged mono a pair might. Power aside, the distortion and noise characteristics of this amp is extraordinary and its unique feed-forward topology pegs the output signal profile as nearly identical whether stereo or mono. The only difference is that the damping factor goes to half in mono, but chopping your speaker cables to half length corrects that. They maintain their operating characteristics to below 1.5 ohms. It took me awhile to get comfortable with their operation and differences from 'normal' amps. I'm hooked. You can read all about it at
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roxy54 Since the mid 90s, I have used a pair of Classe DR9s in mono for my professional studio and consulting needs. They were more than adequate, especially via RCA inputs rather than the OpAmp quasi balanced mode. After I bought Thiel' Audio's ashes in 2018, I migrated to a Benchmark stack (DAC3B, HPA4 headphone/preamp, and a pair of AHB2 power amps.) They meet my present playback and research needs very well. Along this recent path I wanted ways to power Thiel's difficult loads at prices musicians could afford. To that end I've tested a lot of gear that comes across my radar - much of it via this forum. Adcom was such an exploration. Here's a snatch of what I learned. Some of the Adcom gear was designed by Nelson Pass, whom I adore. Much other of their gear is more ordinary. In particular the GFA555 (straight) was Nelson's shot at simple, clean, innovative design that checked his boxes of voltage/current stability, short signal path, stability into low impedance, etc. I bought a low serial number GFA555 and later a higher number 555 and then (on recommendation) a 555 MkII. My evaluation was the low# 555 was clean and direct, the higher# 555 was somewhat shouty and jittery and the MkII was smoother, less engaging, more ordinary. Jim Williams of Audio Upgrades in Carlsbad rebuilds/ upgrades studio recording consuls. He hotrods the GFA555 (not MkII) and informed me that Nelson's 555 depends on high quality parts to shine. The early 555 renditions featured best of form Japanese components assembled in Japan. Later they went to Taiwanese parts and board assembly. The MkII was a French outsourced design that shared only the chassis from the original 555 plus the name. I sent one of my 555s to Jim. The upgrade was wonderful. Increased bandwidth on both ends, better transient speed and settling time, noise floor, etc. all substantially improved. For a few hundred bucks. That amp went to Bill Thalmann of Music Technology for audiophile tweak recommendations. Then back to Jim for implementation including best of form film resistors, etc. Point of exercise is to create a no-excuses solution with under $1K investment for folks in my world. The Adcoms don't perform at the Benchmark level. And the Benchmark might be outclassed by high end gear, usually at prices beyond the reach of most. I'm thrilled with the Benchmark's performance and price; plus the Adcom GFA555 (modified) and Classé (modified) ground me to my personal history with performance that I judge as really fine, especially considering price. |
@tomthiel, The Benchamark amps set the bar for SINAD when first intorduced. It has been surpased by a few since then. But it's become rather academic, as those in the know claim that some where between -115 to -120 dB SINAD becomes inaudible to human hearing even in anechoic conditions. The Benchmarks also allows for user adjustabillity to permit playing nice with a variety of accompaning components. All in all, a rather very, very good prouct....In the right applications. Benchamark does not spec their stereo amp to below 3 Ohms, and their bridged monos to below 6 Ohms. Neither of these amps meet Jim's recommended minimums into the actual load of a speaker like the CS 2.4's. I'm not sure what ..."They maintain their operating characteristics to below 1.5 Ohms."..actually means? Is this similar to the marketing techno babble of "stability"? I don't think halving the length of speaker cable in domestic situations is going to change that. And, I don't imagine such advice is all that practical in most domestic situations. I don't know how much using uniquely customized amps to address the need for inexpensive amps for musicians to drive the more difficult Thiel loads really is? I get it...ultimately we are in this for enjoyment, and if these amps provide that, so be it. But the Benchmarks, while less expensive than many competitiors, is still not cheap, especially in bridged mono mode. At these prices I think there are better reccomendations available to maximize the potential of the more difficult Thiel loads.
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unsound - the 1.5 figure is from John Siau, the amp's designer. Their feed-forward topology maintains stability until it doesn't - when it interrupts the circuit. BTW: I'm all ears for your 'better recommenddations'. The 6' speaker cables came from my feedback to John re the looser bass of the bridged mono configuration. Clearly audible improvement chopping my Straightwire Octave 12' cables in half. I use my 6' cables from my centered amp stack. I suppose the old amp thing is my personal hobby. There are so many GFA555s out there for a couple hundred bucks and with a few more hundred bucks, they greatly outperform whatever these 'normal', non-audiophile people are using. That solution appeals to me. I wish two things. Larger BM amps, which John Siau rejects the need for, and higher impedance loads from Thiel speakers, which Jim Thiel rejected the need for. That's a long talk in itself. |
@tom thiel, I expected as much; the 1.5 figure had marketing speak stamped all over it. Well I suppose it's an improvement from the old "Flame Linear" days, but can they just make an amp that delivers the goods, without cutting out in self preservation? Imagine if your automobile engine worked like that Reccomendations would include old recently recapped/refreshed stand by's like some of the Krells, Levinsons, Thresholds, etc.. Amps that Jim used himself when he was developing these speakers. Standard cable lengths tend to be between 8'-10'. Most users use the shortest lengths that they can. Most can not go much shorter and still allow for domestice accomodations. Cable length can affect amplifier performance, but at these lengths with typical cables, not by that much, Not likely to add lots of Watts to the output at lower impedances I too appreciate old amps, Just as some old houses have better "bones" than some newer construction. And, many if not most could use a refresh of new caps, etc.. That they can weight quite a bit, shipping can be expensive if not perilous. I think it most economical to try and find one that has varifiable maintance recently completed. I agree with your assemsment of the Adcoms. Perhaps the least expensive amps that could actully properly drive some Thiels. I will say that I did have one for long term loan once. Though I had thought due to it's grooved face plate sans rack mounts, that it was a Mark II, I now realize that the time frame preceded the Mark II. I had much easier to drive CS 2's at the time, I have to admit that I found it flat, grainy and lacking dimensionality. I also found myslef just not listening to my system as much with that Adcom in the my system, Still for the money, for someone looking for something to tide them over until the could aquire something better, it could be the least expensive option worth considering. Here's another outfit that has had a good long standing reputation for Adcom mods: I share your wishes. I humbly think Jim went in the wrong direction with regard to impedance. Interesingly the previous generations were especailly easy in that regard. I think amp manufacturers don't want to make capable amps due to the costs of beefier power supplies, additional costly heat sinks. While Class D has made many strides, load variance has been a bit of a bugaboo for them. Until very recently. There's been promise of a high power low impedance option from Purifi, but these things always seem to take much longer than projected to actually make it o market. |
A lot of amps do not have published specs in the 2 Ohm region but that does not mean that it can operate there. My Benchmark AHB2 x 2 on the Thiel worked well but it did not make the low end shine. My new speakers are easier to drive and I will like to get an AHB2 again because I miss that sound. I do like my current amp, the CODA #16 which would be great on the Thiel's. I have a Magnepan LRS+ in my office ($999). It is a killer speaker but very had to drive like my old Thiel CS3.7. No way I would even try the AHB2 on it. It took me a while to find an amp to drive them. I now use the Sanders MagTech amp which is 500 and 900 at 8 and 4. It does not have published specs at 2 but given the explosive way it drives the LRS+. I am sure it is good at 2 Ohms. I was thinking this amp would be great with the Thiel CS3.7. I bought a used MagTech from the Sanders web site for $4k. Thiel users should consider it.
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Thiel 1.5 Right speaker(without polarity markings) 100 hz ---------- 4.100 120 ‐-‐------------3.6565 400 ‐--------------3.6626 1khz -------------4.169 4khz -------------4.210 10khz -----------4.445 Left speaker (with polarity markings) 100 hz ---------- 3.9187 120 ‐-‐------------ 3.6039 400 ‐-------------- 3.6251 1khz ------------- 4.120 4khz ------------- 4.224 10khz ----------- 4.449
Thiel 3.6 Left speaker(after replacing a resistor and resolder) 100 hz ---------- 3.0218 120 ‐-‐------------ 2.7144 400 ‐-------------- 2.6676 1khz ------------- 2.9541 4khz ------------- 2.4293 10khz ----------- 3.1372
Right speaker 100 hz ---------- 2.8188 120 ‐-‐------------ 2.738 400 ‐-------------- 2.6377 1khz ------------- 2.9 4khz ------------- 2.3977 10khz ----------- 3.11
Instead of speculating how hard they can be to Drive. Here it is, some impedance measurements. While not benign, I don't think it should be hard for A competent amplifier with large energy reserves.
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Roxy54 - it's hard to know. I had some clues from an acquaintance who had been personal secretary to Adcom's president in the day. She advised me to find an 'original' and helped puzzle it out. It's not uncommon for a manufacturer to create a worthy product, get good reviews and dealer buy-in and then erode that foundation via lower cost components, sources and so forth. I was personally chagrined to see some late Thiel CS2.4s that didn't hold a candle to the original Lexington variety. So the world goes. I suggest keeping an open mind to the potential of the GFA555. Nelson still loves it as designed; and we have certainly taken it up a few notches. |
tomthiel Thank You for the Power Amp(s) update. Good to read that you are making the most R&D via Adcom, Benchmark and Classe'. Believe me, there is plenty of room, in the room, for Power Amps. We all have our likes and hear differently. Specifications are start but the Ear/Brain give a better clinical picture. I will keep saying that we (Audiophiles) need more "modders" in Our hobby, continuing to push for The Absolute Sound.
Season's Greetings and Happy Listening! |
Re: the Adcoms; While there may have been been better vintages, I'm not sure there were really "bad" ones, as these were really built to a price point. Though it must be said that the original 565 monos were know to be failure prone due to a reputed design flaw. An after market board was made avialble as a fix. Nelson Pass tended to shy away from protection circuitry as he thought such things compromised sound quality. With higher end, overbuilt products like the Thresholds for example that only used 20% of their output devices capabilities, such practices probably made more sense than with targeted price point products like the Adcoms. It should be noted that the Adcom 555 could not ideally double down to 4 Ohms, and when tested blew fuses when pushed hard into 2 Ohms. The 555 is probably better suited for some ot the older >4 Ohm load Thiels. Adcom GFA-555 power amplifier 1989 Measurements | Stereophile.com
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I had a pair of the Adcom 565s and they were terrible sounding and lacked dynamic scale and punch. Up and left my crib soon after..Saw several pairs of Thiels unwound by the use or misuse of Adcom amps. Sonically not much of an improvement over Denon receivers they could play louder but sounded similar. TomD |
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@theaudiotweak, Perhaps I was being too generous / forgiving of the Adcom’s as I do seem to remember reports of those 565 mono’s failing and sometimes tsking out speakers in the process, |
Greetings everyone and happy holidays. I wanted to weigh in with some comments about my new amp and preamp. I recently sold my PS Audio BHK mono blocks and got a Coda 16 amp. The sonic differences were subtle and someone else may prefer the PS amps, but i did like the Coda a bit better. The main reason for the change was I was no longer interested in messing with tubes. However the big sonic improvement was when i moved from a Pass XP22 to the Coda 07X preamp. The Coda pre really seems to bring out the best in my Thiel 3.7’s. It is a much more musical unit and I think a much better sonic match to the speakers. The Pass would very likely be better with speakers that are softer and more rounded on the top. |
Hi guys, a friend mine asked me if i wanted to demo his monster Pilium Leonidas integrated on my 3.7s. This is the typical integrated that loves difficult load speakers and can easily drive 2ohms. Its is also very smooth like Pass Labs so will keep you guys posted when we can do this Pilium demo at my place, should be fun. |
@roxy54 A powerhouse lol |
Jafant
Thanks for the welcoming reply. Actually, the NAD is my first “step up” in gear. Aside from that my collection is pretty much all vintage every day components. I have several receivers like a Sansui 8080, Kenwood KR7400 and Sherwood SEL200 to name a few. Turntables include an AR XA, Concept 2QD, Technics SL 1500 and few more. I have several pairs of speakers like Bozak B313’s, KEF Reference 103.2, ADS L810, Dynaco A25 and stacked OLA’s. All these get rotated into various systems in the house. My “main” which gets most use would currently be the Sansui, Concept and ADS combo in my office. I have been looking to, again, step things up and came upon the Thiel 1.6’s for a good price. Then I started looking for an amp that was good and with sufficient power for the Thiels and found the NAD C375BEE. So here I am. My budget is somewhat limited so I am doing the best I can with the money I have to spend on “stuff like this” along with what is available in the local market…..pretty happy so far….😎. Currently the Thiels/NAD are in the garage as I needed to test everything to be sure it all worked/sounded as it should. Next for them is the family room….. |
I still daydream about my Thiel 3.6's, which I sold some years ago, and sometimes I think I should get another pair. But, when I had my 3.6's, I powered them with a Krell KSA 200, and the sound was glorious. Nowadays, though, my amplification is an Ayre AX 5-20. I would appreciate anyone's comments on how the Ayre would pair with 3.6's, in case I get the opportunity to move back to Thiels. |
