@coop_301 , Something to consider; some of these amps are getting up there in age, and might be due for a recapping and perhaps re-biasing. The cost of which may not be inexpensive, especially when considering the weight and corresponding shipping costs. Occasionally one might find one for sale with documentation that this had recently been done by the factory or an approved tech. Be careful of unapproved workmanship. If you can find an appropriately updated amp, you might find a killer value.
Showing 50 responses by unsound
@coop_301 , Another consideration is to purchase an amp on the condition that it passes an authorized tech inspection. In which case you might avoid some risk, could get the amp properly updated, and as such eventually save money on at least one delivery trip expense. |
@coop_301 , Please indulge me as I offer some thoughts. IMHO, the CS 6's play with greater ease and with greater dynamic range than the CS 3.6's, at a very premium price difference (at least when new). If you have a rather large room or intend to play your music very loud the CS 6's might be a better choice, otherwise the better value could be the CS 3.6's. A contributor that I've long come to respect here on Audiogon @pops has extensive experience with both, hopefully he'll add his thoughts. As for the Krell KAV 1500, it's really a bridgeable 5 channel amp. The Krell KAV series was introduced to cater to the then growing Home Theatre market. They are biased more into Class AB, don't have the low impedance prowess of the built for audio biased into Class A and capable of doubling down with impedances of some of their more audio centric models. The KAV 1500's 5 channels can be bridged, but that's not something that I would consider with these Thiel models and their rather low impedance loads. Not all Krells fit the stereotypical (ha!) model that comes to mind when one hears the name Krell. I'm not at all surprised that you preferred the CS 6's driven by the ML 23.5. I say this despite more often than not preferring the house sound of many Krells to Mark Levinson's. When I was much younger, I believed that the most important component were the speakers and therefore most of one's budget should be spent there. I still believe that speakers are the most important component (after budget and room) but no longer necessarily believe that that should dictate budget. The used market has changed that. Market value and intrinsic value do not always run parallel. Speakers and amps are more dependent on compatibility than most components and this is especially true for these and many other Thiel models. Unless one intends to upgrade in the very near future, and caution must be used in that case, the combinations results can be more important than the individual prowess. As always, the above is IMHO, YMMV! |
@thoft, OK, then you might not need the pre-amp part. As the eq only has single ended inputs and outputs, I wouldn’t be too concerned with the DAC’s balanced output performance. The Adcom GFA-5800 has a gain of 29 dB for full output via it’s RCA inputs. The equation for sensitivity escapes me for the moment (perhaps one of the other contributors can chime in) but an output of about 2 V ( 2V being the redbook standard, and 2.2 V the standard for HDCD, though for some reason quite a few DAC manufacturers seem to ignore these standards) or less will probably do. Many of today’s DAC’s have 32 bits or more capability, so long as the DAC has a volume control, and doesn’t have an especially high output, you’ll have bit’s to spare even with most hi rez material, with such a DAC there’s no worry of bit stripping due to reduced volume output. Though somewhat more unlikely: too low of an output from the DAC will prohibit the amp from offering full output. While some DAC’s offer eq functionality, most don’t have the 12 db range to adequately substitute for Thiel’s own eq. If you could find a DAC with the needed eq prerequisites, you could reopen the consideration of going balanced. But be warned, that even though the Adcom GFA’s rather unique reduced to 26 dB gain for it’s balanced inputs, the output of many if not most DAC’s balanced connections are often double that of it’s RCA outputs, and the concurrent required volume reduction could lead to a greater chance of bit stripping. If your using Tidal as your main streaming service, it's probably worth it to consider MQA capability. |
@thoft, the Adcom GFA - 5800 is rated as 400 Watts into 4 Ohms: https://www.manualslib.com/manual/206141/Adcom-Gfa-5800.html?page=11#manual While it might very well be up to the task, one can see that it's not quite up to doubling down from 8 Ohms to 4 Ohms and there isn't a 2 Ohm rating. Unlike your 3.5's these model Thiel's have sub 3 Ohm loads: https://www.stereophile.com/content/thiel-cs37-loudspeaker-measurements https://www.stereophile.com/content/thiel-cs72-loudspeaker-measurements |
@thoft, Hold on. You might not actually prefer these to the 3.5’s. The 3.5’s will actually play deeper in the bass and do so with greater cohesion. The 3.7’s are better at dealing with the lobbing issues, both are more dynamic, especially the 7.2’s. The cost of amplification will certainly go up with either. On the other hand, replacement parts are much more available than are for the 3.5s. The BHK 250’s : https://www.psaudio.com/products/bhk-signature-amplifier/#tab-specs aren’t rated into 2 Ohms, being " 2 Ohm ....stable into musical transients" only suggests that the amp won’t go into oscillation when temporarily confronted with such a load. Same for the M700’s: https://www.psaudio.com/products/stellar-m700-power-amplifier/#tab-specs Class D amps are not typically comfortable with sub 4 Ohm loads, The BHK 300’s seem up to the task, but not especially enjoying it: https://www.stereophile.com/content/ps-audio-bhk-signature-300-monoblock-power-amplifier-measurement... These later Thiel’s don’t just visit these lower impedances; they live there: https://www.stereophile.com/content/thiel-cs72-loudspeaker-measurements https://www.stereophile.com/content/thiel-cs37-loudspeaker-measurements @Thieliste has given excellent advice recommending some of the best amps for these speakers. The Momentum amps jump to mind as well. The Gryphon’s are probably the best amps I’ve ever heard, but the are not inexpensive(!), and the US distribution has been inconsistent in the past, new ownership seemingly following the originators design philosophy might change that, but the possibility of having to ship these heavy amps back to Denmark is a bit daunting to me. The Krells seem to need to be recapped a bit more often than some others and that’s not cheap either, though IMHO worth it. The Luxman specs are somewhat ambiguous. |
It might be true. But, you know what they say about opinions. Unless, one really knows the listener and their perceptions and their experience, or there is consensus from an adequate sample size, I suggest prioritizing the objective information first. If an amp manufacturer can deliver the goods into a low impedance, they will brag about it. On the other hand, specs and measurements are only prerequisites for narrowing down the suitable prospective choices. After that, there are elements of the sound that at this time escape those criterion. I suggest dealing with what we do know before venturing into the unknown. Not doing so is tantamount to traveling to an unknown destination in the dark. |
@thoft, re: Aragon 2 Ohm capability, I think not: http://www.aragonav.com/legacy Notice none are rated into 2 Ohms The 8008 didn’t fare too well when tested into 2 Ohms: https://www.stereophile.com/content/aragon-8008-power-amplifier-measurements |
@thoft, I remember Stereophile giving something of a mixed review of a Lazurus hybrid preamp in the mid 90’s. http://www.incarock.com/preamps/lpa.htm You’re much more trusting, and willing risk taker than I am. If you’re really looking for an amp to drive the 3.7’s for less than $10K, why not use the main one that Jim Thiel used when developing the 3.7’s: Krell FPB 600 ? You can find one used and have Krell rebuild it for about less than that. If you’ve got a smaller room or budget, you can go with a less powerful version. https://www.stereophile.com/solidpoweramps/829/index.html |
@scubabird, I too think the closest model to the legacy Thiel’s currently made at that price point is the Vandersteen 2’s. On the other hand, the attributes that you singled out; ...”exceptional detail and clarity...”...is where they separate the most. The Magnepans previously mentioned share most similarly in transient response and to some degree in coherence (compared to others), but are quite different in other ways. Based upon your previous post, I think you’d be happiest with genuine legacy Thiel’s. |
@thoft, Mondial claims it increases power into 2 and 1 Ohms, but it won’t say by how much or for how long. Keep in mind that when an amplifier is doubling down power with each halving of impedance, that typical speakers are decreasing sensitivity by 3dB with each halving of impedance as well. Which at high power levels can lead to frequency nonlinearities, increased distortion levels, and perhaps even potentially driver damaging clipping. if the amp can’t keep up. That their 8008 blew it’s fuse after a short period of high level output into 2 Ohms during independent testing suggests there’s a chance that their claim might be little more than a parlor trick. If they can’t maintain it, they’re not likely to spec it. Which is why one often sees things like "stable" or for "musical transients". Which often means that it can do it, but not maintain it for more than a brief moment. Notice the specs for: https://www.krellhifi.com/wp-content/uploads/2020/04/Krell_FPB_CAST_SERIES_Owners_Reference.pdf or https://gryphon-audio.dk/wp-content/uploads/2020/05/Tech.-Spec.-ALL-Products-05032020.pdf The mighty Gryphon’s bigger amps spec’d to 1 Ohm, the smaller amps (and unusually even their integrated!!!) spec’d down to 2 Ohms. or https://dandagostino.com/products/momentum-mono.php This is what one wants for the low impedance Thiels. Not all models from all these brands measure up the same. |
@xyzsantabarbara, Though Thiel Audio is usually better than most at posting their specs, I think you'll find the following interesting: https://www.stereophile.com/content/thiel-cs37-loudspeaker- specifications https://www.stereophile.com/content/thiel-cs37-loudspeaker-measurements Whether it's due to different measuring techniques or rounding to standard numerations, I think the 4 Ohm nominal rating is a bit off. The Stereophile measurements suggest a low of 2.4 Ohms and the graph looks more like a nominal 3 Ohm rating to me. And with a difficult phase angle to boot. I'd suggest working from that 2.4 Ohm minimum impedance when gauging for appropriate amplification. |
^Though I’m confident that most already know not to over generalize a brands different product models comparabilities, it might be even more so the case with B&K’s and Thiel’s. Most B&K’s aren’t particularly suitable with most Thiel’s. But, there are some notable exceptions that work particularly well on their own merits, and just so happen to offer very good value while doing so. |
^A minimum of 400 Watts into 2 Ohms is excellent advice. Depending on ones room and desired volume output, multiples of that power output into 2 Ohms could be appreciated. As far as preamplifiers go, much of it depends on the specific amplification and source components used, it’s possible that you might not even need one. |
^While your point has merit consider that ; the 92db sensitivity rating is a standard rating into 8 Ohms. Drop 3 dB for each halving of impedance from there. Now we’re looking at something that is actually closer to 86 dB sensitivity. Which is why doubling down maintains frequency linearity. Jim Thiel told me himself that the power recommendations made were for standard 8 Ohm power ratings for amplifiers capable of doubling down, and if one were to use say a tube amp one should double the power recommendations as necessary. Thiel recommended 100 Watts minimum for the 3.7’s into 8 Ohms, doubling down into 2 Ohms would bring that recommendation to 400 Watts into 2 Ohms. |
@xyzsantabarbara, As I understand it; yes. I believe many of the Krell’s do, that the Mark Levinson ML 2’s did, some of the Pass Labs might (limited to 4 Ohms maybe?)? I wouldn’t swear on it though. I’ll hazard a guess that the Class A output is halved as the output doubles as impedance is halved. Though most times one cruises along at low power output, that output increases rather dramatically exponentially. You’ll have to decide how relevant the Class A output in your circumstances. Keep in mind that available higher total output can potentially protect drivers from under powered clipping damage, and the ear tends to be less sensitive to the cross-over distortions of Class AB at higher volume levels. These are the areas that separates typically have advantages over their integrated brethren; the ability to double down and and the ability to stay in Class A output longer when doing so. |
I’m not trying to discourage you from using DSP, just what might be involved. I think having the speakers right up against the wall behind the speakers could reduce demands on the amp, and perhaps more importantly not over correct the direct primary sound from the corrected reflected room sound, as the two sounds will be so similar. |
^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. |
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. |
@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. |
@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! |
@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. |
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. |
@dsper, Some of the Meadowlark’s have similar design goals as the Thiel’s and are more accommodating of tubes. With that said, some of them used now irreplaceable drivers, and IMHO the Thiel’s are just better, Then again, while I can appreciate some of the charms of tubes, ultimately I prefer ss, YMMV. |
@yyzsantabarbara, There are a multiple number of causes that might be responsible for this anomaly (including room). I’d suggest reversing components (speakers and cables) and channels from one channel to the other starting from the end (speakers) to the front of the chain.Then replacing components in the same manner. This might help you find the culprit. |