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In use
The chromed front is 'dual diff' too - symmetrical, with the back-lit Thorens logo in the middle, the IR eye below. To the left is the big input selector to choose between 5 line-level inputs, one fixed (a home-theater thru-put) and a tape monitor. Alternately, selection can be made with the wood-encased remote since input switching is by relay. The big right control of course is for volume. Very attractively, its setting is confirmed with a wandering blue dot on a back-lit line that circles the knob*. When display off is selected, only this dot remains lit to confirm power on. Four small chromed push buttons line up with the IR eye below. They are, from left to right, power, monitor, -14dB and mute. The minus 14dB function is an attenuation deccelerator. It operates only in the middle of the Alps taper for even narrower progressions such that in the most-used range, the remote or hand forward in only very small increments. Brilliant.

*"The blue dot for the volume regulator required an extra effort. Using just a blue LED would cause a smudge. Fortunately I am used to dealing with light so a specially designed light conductor found its way into this preamp for generating a crisp blue and moving dot for the right analog feeling while turning the volume control."

Around back, we find a strangely anachronistic choice of tape loop rather than twinned pre-outs of both RCA and XLR persuasions. Because of its standard width, Blöhbaum was limited to the amount of socketry he could fit. Thorens dealers asked for 4 RCA inputs + fixed + a tape loop + 2 balanced inputs. That only left room for one RCA and XLR pre-out each, mandating an ugly Y-connector if you want to bi-amp in either flavor. I seriously doubt that a target customer for a €15,000 esoteric valve preamp dubs to tape. I'd have lost the monitor loop i/o ports and converted them to two additional pre-outs, one single-ended, one balanced.*

*"We had a team to make the decision on input and output connectors and some other features. I was a member of that team and will not shirk responsibility. We had worked out a specifications requirement as the result of many talks with dealers and customers and we observed the market very carefully. The TEP 3800 was to be an all-in-one device suitable for every purpose, not just become the matching preamp for the TEM 3200. Our top priority was the equal usability for RCA and XLR equipped devices without any compromises in sound quality because there is nearly no standard in the high-end audio market. And it was our goal that almost all devices should be connectable while producing the best possible music playback.

"Thus the TEP 3800 has top-quality XLR and cinch outputs where most competitors compromise for one or the other. The XLR output feeds directly into the main amp. The cinch output is driven by a costly extra circuit which converts the symmetric signal into an non-symmetric one in the best possible way where others simply strip out one pole of the differential feed. The next priority was the availability of always 6 inputs, 2 of them Cinch or XLR. One additional major requirement was the width of the preamp, which should not exceed the typical rack format of about 43 to 44cm. That caused a lot of headaches because of the limited amount of heat (with 12 tubes inside!) which can be safely vented out of the housing. And you know me, safely means
really safe and reliable. As such, the device never runs hot and only slightly warm. Following the dealer feedback, a tape loop was a must. Some customers still use DAT recorders and/or tape machines, others use the tape loop for dubbing their own videos and some work in a professional environment feeding active monitors where the tape loop feeds external sound processors. So there was no room left for more output connectors.

"Of course we discussed the necessity of doubled cinch and/or XLR connectors and which feature should be substituted for it. Doubled outputs are important for bi-amping customers. Almost all customers in this price range have power amps with at least one XLR input or XLR and cinch. For those there is definitely no problem. The difference of sound quality between the outputs is practically zero. If the power amp only has an XLR input like the TEM 3200 monos do, it is recommended to use the cinch output with a cinch-to-XLR adapter. Some customers have used exactly that and are enthusiastic about their sound experience. Up to now we had not one customer complain about missing an additional cinch preamp output. We had one inquiry for two XLR outputs but we listen very carefully to feedback from testers and dealer and owners."

The core specifications tell us that the Thorens TEP 3800 is no run-of-the-mill preamp gussied up in gleaming chrome and wooden cheeks of various color options. First off, frequency response into 10Kohm is 0.7Hz to 600kHz -3dB. Then S/N ratio based on a 1V output level is 98/96dB for XLR/RCA respectively. The Thorens TEP 3800 and TEM 3200 components are assembled in the German Isophon speaker manufacturing plant and, for obvious reasons, low-volume products that require highly trained specialist hand labor.

Clicking on the above image opens to 2000 x 1500 at 448KB in a new window and nicely shows the internal tube structures

That the former East-German Blöhbaum lives and breathes tubes was demonstrated further with his "proof of concept preamp, which I made for the ETF 08 European Triode Festival in Holland. It took part in the so-called 'sound processor shoot out'. The goal was that the music coming out of the box sound better than the signal entering. Such an approach most definitely does not fit my design philosophy but I liked to take part with an exotic approach. Because ETF 08 took place in the Netherlands, I chose a typical Dutch tube for amplification, one of the famous "Red Series" from about 1936. And to make it more challenging, it is also a tube never before used for hifi: the EK2 octode with 6 grids having a remote cutoff characteristic which is prohibitive for linear amplification. But I incorporated some special tricks and the result was, this little amp became the winner of the shoot out. Of course it was more a big fun game than a serious test. One part of the fun though was that I could change the octode EK2 to a triode-hexode ECH3 with inner connected grids and a shared cathode - no less exotic than an octode."

Will we ever see formal Blöhbaum System-branded components as the professional engraving of the ETF 08 demonstrator might presage? "I already have a demanding full-time research job. I do audio purely because it's my passion. But I'm not a sales & marketing man. My work for Thorens and Uwe Bartel at Sintron on a contract basis thus serves me perfectly. I get to develop novel tube circuits, they handle the manufacture and selling. Heinz at Thorens is very open about my contributions which I appreciate very much because it need not be part of such arrangements at all. As you said earlier, many engineers like me are anonymous ghost writers who never get credit for their work. I'm very pleased with Thorens' generosity in that regard. Heinz even allowed me to silk screen my proprietary modules. Anyone opening the preamp or monos sees the Blöhbaum System name and it's also silk screened on the back panel."

"I know you've lived abroad for half your life and are probably only now discovering much of the hifi scene in your native Germany. It might interest you then to know that both German print magazines and arch rivals at that already published reviews on the TEP 3800. Quite out of character, they agreed with each other and rated it among the best if not the best preamp they ever tested. It's good to observe both the Stereo and Stereoplay tests. The Stereoplay test bench delivered a graph of harmonic spectra depending on output amplitude. This graph shows why this preamp is praised for its transparency. There is no change of the relation between each specific harmonic and each other from the low end of just perceptible whispers to ear-cracking levels. The absolute value of distortion is extremely low. The measured figures of Stereo magazine show 0.0002% @ 1V output. Most high-end people believe that such low distortion will end up in anemic, cold, clinical sound. It's remarkable that especially Stereo magazine -- which is known for favoring some voodoo tricks and beliefs -- praised the musicality of the TEP 3800. Also look at the other values like channel separation of 73dB. Stereo measures that at 10kHz! One footnote: The measured output impedance of 56 ohm is for cinch. The XLR has a stunning 0.67 Ohm output impedance. The complete Stereo test can be found here."

The heart of the TEP 3800. This image opens to 1852 x 1656 at 419KB in a new window

6moons is thus late to this party. Again. We also were with the monos. At best we'll agree with our German colleagues (again); at worst we'll shed new and different light. Which would it be?