Thoeress Phono Equalizer/Enhancer.

Thoeress Phono Equalizer/Enhancer.

For listening evaluation, Thoeress' phono replaced our standard reference phono preamplifier (Rotel RHQ-10 "Michi") and connected to one of Melos Plus Series Line preamplifier line-level inputs. The rest of the system included the Parasound HCA3500 power amplifier and the ATC SCM-50 PSL loudspeakers. As a source, a Linn Sondek LP12 (Linn Ittok/Karma) was used, connected to the Thoeress 100 Ohm moving coil input.
Initial installation/setup of the preamplifier does not hide any particular difficulties, although the chassis size and mainly its height and the need to have some room for the air to circulate, sets some requirements in terms of the distance between of the shelves of a rack. Otherwise, all the user has to do is to connect the appropriate cables to the right places. If the unfortunate event of a ground loop occurs, a "Ground Lift" switch allows the user to control the grounding path in order to solve the problem.
The evaluation was done in two stages. The first part was related to our impressions of using the device as a conventional phono preamplifier, with all the controls set to their "RIAA" position. The second (and probably more interesting) stage involved the practical possibilities offered by adjusting the de-emphasis curve.
As a conventional phono preamplifier, Thoeress clearly shows its basic virtues: These include a transparent and precise behavior, a low noise floor and some very good potential to pass the turntable/arm/cartridge features into the listening room without any additional character. It is obvious, even from the first minutes of critical listening, that the tube-based circuit is quite neutral and, in this respect, the preamplifier does justice to its looks: It is, indeed, a serious professional tool for vinyl record reproduction and not just a complex (and expensive) toy for audiophiles looking for specific sound "qualities".
With the Thoeress phono in place, the system maintained its balanced and easy-to-the-ear behavior, in which I'm accustomed to, with the somewhat emphatic lows from the LP12, with good high-frequency extension and very good stereo imaging. Description of the very low part of the audio spectrum was excellent with a sense of detail, bass parts retained their attack attributes and were well balanced and rhythm section parts were fast enough with good microdynamics and no slackness.
Midrange appeared vibrant and well balanced, with solo voices and musical instruments to hold an imposing presence and great articulation, while the choir retained its size scale and its room-filling impression. In general, description of an acoustic space is one of the Thoeress' strongest feaures and paired with a cartridge with top channel separation could create a very interesting, clear and stable stereo image.
Soundstage appears well focused with an accurate description of both the position and the movement of individual audio objects, with a good description of the air between the instruments and the whole soundscape, either preserved or created from scratch during mixing.
The high-frequency part of the spectrum was presented with a good feeling of extension, good attack times, full bodied and with somewhat faster decay times than the reference preamplifier, a feature led to a more distinguishable detail rendering. Harmonics were perfectly presented and the end result was warm and pleasant but not excessively so. The preamplifier has been very good both in macrodynamics, probably due to its low noise and very good behavior on program peaks where there was no compression or harshness, and in microdynamics with very good speed and detail, which is expected, since it is a device with about 30kHz bandwidth. In this respect, Thoeress was clearly better compared to the reference preamp, being much more comfortable, with a wider dynamic range and, therefore, more transparent in processing the information provided by the source.

Thoeress Phono Equalizer/Enhancer.
Thoeress Phono Equalizer/Enhancer.

Beyond its use as a conventional phono preamp, however, Thoeress' main advantage is that it offers the possibility to improve (or correct, if you prefer this term) the record playback by selecting a set of different settings via its controls. The company, in a very well written (though without many technical details and specs) user's manual, gives some basic guidelines for a correct setting procedure, insisting to start from the mid/low adjustment, followed by corrections in the lower part of the spectrum (the choices in these two bands seem to have a certain interaction) and finalize the whole endeavor with the high frequency setting, reminding at the same time that the various settings should be documented per record. This final part of the instructions is important: Thoeress rightly considers that the corrections made are closely related to the features of the record and -arguing by extension- it is not a good idea to try to fix problems due to the source or to the rest of the system or to room acoustics. In turn, this idea leads a step further: for one to "correct" a record using Thoeress, it is necessary to be sure about the neutrality of the rest of the system (or -at least- of the system parts after Thoeress). Quirky amplifiers and loudspeakers or excessive problems in room acoustics may lead to wrong settings and will have no meaning except in this, specific, setup (in other words, if you move your system to another room or if you change your loudspeakers or amps, you need to find the settings again for each record -not good). To avoid this unpleasant possibility, it would not be a bad idea (at least to my opinion) to make some critical listening with a good pair of headphones (the "good" here, meaning, mainly "neutral"). The headphones leave off room acoustics and are a simpler system in general.
In practice, now, the use of preamplifier in this mode is really enjoyable. The effect of each adjustment is, most times, quite clear but always gentle and after a few hours of use, one can very easily not only make some settings that make sense but, also, to approach the correct value for each setting with just a little listening of each record and without tinkering too much. For records you know well, you may not even need to listen to them (however, this is not a suggestion, just an observation…).
To fully exploit the potential of the device, though, you need to perform some serious listening, and gain some experience to avoid adjustments that are "spectacular" instead of "correct". Our use of the Thoeress showed that any decision probably has a cost against which should be weighted for. For example, filling-in the low-frequency part of a "thin" record, could amplify any mechanical problems the turntable suffers from, while enhancing the high-frequency content could also enhance the disc surface noise. Therefore, to use Thoeress effectively you need a good, correctly set-up, turntable, clean records and a decently neutral system. Correct state of mind is, also, a prerequisite here: The review showed that user needs to approach any correction procedure through a "null-hypothesis testing-like" path, i.e by assuming that there is no need for correction and look hard for any clues that this is not the case. Also, at some point, he, probably, will have to compromise: Thoeress (or any such tool for that matter) cannot correct every record on any aspect.
One useful example of our use of the Enhancer can be found in the listening sessions recordings. The corresponding file contains one of the four tracks we usually include but with the adjustment listed in the lab evaluation page (4-4-2, referring to the control positions from left to right).


Reinhard Thoeress' phono far exceeded the expectations we had for this kind of device. For starters, it is quite successful as a standard phono preamplifier featuring low noise, good de-emphasis accuracy, and good dynamics, resulting in a neutral, transparent stage that will not restrict the potential of a good analog front-end. Secondly, if used correctly, it is a first-class tool to correct some problems often encountered in vinyl records and improve the final result, giving new life to your collection. Last but (obviously) not least, it is an excellent "time killer" for any audiophile who believes that a parameter fumbling/fine adjustment procedure offers some serious added value and -even more important- any audiophile who intends to digitize a record collection and needs some control over the final result. All that being said, it is clear that we are dealing with a phono preamplifier that both inspires and stands out. Well done!

Listening Sessions Recording

The following recordings were made with a DV-RA1000 Tascam master recorder (using 24bit/192kHz sample rate) and you can download them to have an impression of what the device under review sounded like. It is obvious that any recording of this kind could not be absolutely transparent but, according to our experience, the majority of sound attributes we listen to, during the actual listening sessions, are preserved. No need to say that you should use these samples cautiously and for informative purposes only. Do not rely on them exclusively to make any buying decisions. The file format is .flac, so expect that the zipped files will be quite large (even if the clips are about a minute or less long. You could use an ABX listening tool like the ABX plug-in for foobar2000 if you want to make some more elaborate experiments. Contact us if you have any questions.

Listening Sessions Recording TOC
Track #01 Linn Sondek LP12/Ittok/Karma, Thoeress RIAA
Track #02 Linn Sondek LP12/Ittok/Karma, Thoeress 4-4-2
Track #03 Reference Tracks: Linn Sondek LP12/Ittok/Karma, Rotel RHQ-10 "Michi"

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