Thiel Owners

@ tmsrdg and @ nkonor
Thanks for your question. It looks like Spectral is getting a lot of attention here recently. I am also a long term Spectral owner, going back to the mid 90s and as I mentioned before I have never had any reliability issues apart from a backlit logo failing 15 years out of warranty. 

 I am only superficially familiar with your Berkley D/A, I have read their reviews. Remember the amplifiers can reproduce high frequencies much higher than the output of the D/A- which is 59KHz . The amps are rated to over a mega or million Hz. Without knowing what the analog circuits are doing at extreme frequencies you are and Spectral techs will confirm that you are running risk of damaging the amplifier. 

In addition, I see the the maximum energy usage of the Berkley is 25-30 Watts, which to me infers that you would likely do better to have the Spectral preamp between the D/A and the amp. Remember the D/A will have to drive not only the interconnect cables, but also the input impedance of the amp. The output of the D/A does not have a current rating but does have a maximum output voltage of 3.25V. The preamps from Spectral typically have a peak to peak voltage capability of 100V and maximum current output of 1amp (!!), fully comfortable with driving difficult loads. 

I have heard the phrases of "wire with gain" or "the best preamp is no preamp." I would agree that it is very counter intuitive to add something between the source and the amplifier and not lose information in the process. But, I have heard in my system, in friend's systems, adding a preamplifier can dramatically improve the sound of the system because it is more comfortable driving the cables + amplifier. By dramatic, I mean in every way- quieter background, deeper bass and drive, complex harmonic textures revealed, wider and deeper soundstage, holographic imaging, more engaging dynamics.

Spectral did make an amplifier called the DMA 150 Universal in the early 2000s that had an extra, small internal circuit board that allowed you to switch the amp to work with a non-Spectral preamplifier. But engaging the circuit that limited the bandwidth of the amp at its input and was detrimental.

I would recommend a preamp. I would gladly trade you one of mine for your CS3.7s :) 

Hope this is helpful and I am happy to have discovered this thread.
Happy listening!

@nkonor & @rascs:


How does Spectral's high-bandwidth, ultra fast designs manifest themselves in the final sound that one hears from the system?  Again, I have not as yet had the pleasure of listening to a Spectral system, but my intrigue grows the more I learn & read about them.

Thanks for any thoughts!

OK, I realize this is getting somewhat off the forum topic, but the folks at Berkeley Audio tell me that they run the Alpha DAC directly into Spectral amps, with excellent results.So right now, I'm looking at the Spectral DMA-300. Specs as follows:Power Output (continuous):
@ 8 ohms - 225 Watts RMS, @ 4 ohms - 410 Watts RMS, @ 2 ohms - 615 Watts RMS
Output Current: 60 Amps peak per channelFrequency Response: a0.1 dB, DC-150 KHz,a1 dB, DC-1 MHz, a3 dB, DC-1.8 MHz
or the DMA 400Power Output (continuous):
@ 8 ohms - 225 Watts RMS,@ 4 ohms - 410 Watts RMS,@ 2 ohms - 615 Watts RMS
Output Current: 60 Amps peak per channel
Frequency Response: same as DMA-300
to use with my Thiel 3.7s in my 20x20x8, one side opening into another room, listening spaceThiel 3.7 specs:
Amplitude Response 33HZ-22kHz +/- 2DB; Sensitivity 90db@2.8 V-1m; Impedance 4 ohms (2.8 minimum), Recommended power 200-600 watts
As far as I can tell, either of these amps would do fine, with the caveat that they do not do the coveted "doubling down." I need some help with this. Any thoughts on these amp/speaker pairings will be greatly appreciated!Todd

My two cents and two thousand words on Spectral products. It seems the only press they get (along with the Berkeley Alpha DAC) is Robert Harley, for better or worse. Goodwins audio outside Boston carry both, and I had a thorough audition of the Alpha DAC in 2012 soon after it first came out, but more to the point here, a good taste of the Spectral DMC 30 preamp (driving non-Spectral amps in this case), after auditioning DACs through a very good ’other’ preamp. On the same material, in comparison, the front-to-rear layering of the soundstage, even on studio recordings, was unlike anything I’d heard in hifi before, combined with a near-holographic stereo image. The top octaves, despite modest digital source material (on a $22,000 dCS CD player), were pristine, precise, super-fast, but entirely natural, and actually seemed on the ’darker’ side of neutral. My initial response was certainly amazement, but that didn’t allow for a more-accurate long-term assessment. As my time in the room (after coming to hear DACs) was finishing up, I couldn’t listen to all I would have liked to, but my impressions were beyond other high-end preamps I’m familiar with, or was .

The company seems pretty low-key, archaic website, and design the best product they can, and leave them alone for years. The preamps have the decent control flexibility I like. It seems the wide bandwidth can cut both ways. There’s certainly no musical information in the MHz, but it does make for perfect transients, even if the high frequency noise screws with downstream amps. My own preamp is spec’d -3dB@>0.5MHz vs Spectral’s 1.5MHz, so I don’t know what frequency the issues begin, but I’m sure there’s more to it. This engineer likes their internal layout, design approach, relevant innovations, product cycle longevity, sane pricing, application of RF instrumentation technologies, true research into semiconductor physics and other details that are taken for granted out of necessity by other high-end designers. I would sure like to audition a DMC-30 at home!

A good friend had Alan Goodwin design a ground-up ultimate listening room within the foundation of his cost-no-object new construction, optimized for 2-channel, but also has 5.1. Spectral DMA-360 amps (and preamp) all around (driving large Avalons), and to my current awareness they’ve been on 24/7 for twenty years without issue. Yes, it sounds amazing, but primarily because of a perfect acoustic, perfect absorption and T60 across all frequencies, and perfect bass loading, something never heard in even a well-treated home room turned listening room.

tmsrdg

"I realize this is getting somewhat off the forum topic, but the folks at Berkeley Audio tell me that they run the Alpha DAC directly into Spectral amps, with excellent results.So right now, I'm looking at the Spectral DMA-300. "

Without being cheeky I think your making a good decision ,
one less interconnect cable , one less power cord leaving 
more $ for your amp or speaker cable upgrade .
I use a passive preamp because I need an attenuator and selector .
 I'm one of the minimalists  , less between the music and the speakers . 
You should look into other forums on the topic passive vs. active ,
in your case preamp or no preamp that is the question .

And The Band Played On 

Rob