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Threshold - T2 reference preamplifier


Edit, 14th october 2007: this review of the original THRESHOLD T2 has been followed by an article related to its upgrade and optimization (transforming the T2 into a true state of the art preamp), which can be read here
. Nevertheless, we recommand you to first read the herebelow review.


The TRESHOLD T2 preamplifier was made from 1994 to 1998. It was designed by Michael BLADELIUS (who also designed most of the FORTE AUDIO amplifiers) assisted by 3 engineers: Mike JAMES, Wayne COLBURN and Larry ROEDENBECK.

The T2 is a very particular device in the history of Threshold: it is the 1st high end element designed after Nelson PASS left the company in 1992 (René BESNE left the company the year before, in 1991). So, at this time, the major question was: "does Threshold still have the necessary resources to produce exceptional audio devices as it did during the Nelson PASS era ? ". Of course, this anwer is yes, because even if the electronic parts come more from Taïwan than from the States or Europe, the musicality  is still here and the build quality is still at the highest levels.

Unfortunately (for us) the Company finally decided to ignore the high end audio products and turned its business exclusively to the professional audio market...


You can find a detailed review in the "download" section.; you have to register as a member (of course, ti is free) to access the download section.



The THRESHOLD T2 preamplifier


The T2 is a 2 chassis preamp: one for the power supply, one for the preamp itself.

The T2 Power Supply:

The PS box is connected to the main chassis with a very long, high quality dedicated cord. It is the heart of the preamp, at it is a very high quality, low noise power supply. THRESHOLD recommends to place the PS box as far as possible from the main T2 unit.

The PS features a 150VA toroidal transformer feeding a 70.000µF bank of capacitors. This 70.000µF is obtained by six ELNA capacitors, [4 x 10.000µF/63V/85°C] and [2 x 15.000µF/35V/85°C]: they can be easily identified by looking at the top view of the power supply unit, later in this article. In addition, a few small WIMA capacitors are used (their color is red).

As in every THRESHOLD product, at least those issued during the golden age of the THRESHOLD brand (i.e during the SA and T series), the Power Supply is oversized, meaning that a lot of commercial power amplifiers would benefit to have a such big power supply....

The T2 has 2 symetrical (XLR) inputs and 2 symetrical XLR outputs, in addition to the classical RCA inputs and outputs. You can use the both outputs at the same time, for example to drive an active subwoofer in addition to your regular loudspeakers. The recent PASS preamplifiers such as the X0.2 preamp (designed by Nelson PASS, the genius who designed the SA STASIS series) from PASS LABORATORIES also offer this feature.



The serial number of each T2 preamplifier is located on the bottom face of the (impressive) power supply.



L'alimentation - vue de face



L'alimentation - vue intérieure


The T2 main chassis:

The build quality of the T2 is similar to the SA and T series, meaning it is built like a tank: the front face is very thick (the thickiest I have seen to date). Although this could be seen only as an aesthetical point, it is not: the rigidity of the cabinet does matter in keeping the active circuits in peace...

The T2 is designed to remain ON all the time: there is no OFF position. It does exist a "Standby" position on the T2, but this position is clearly a standby position and does not turn all the circuits Off. This can easily be verified by putting your hand on the top right of the T2: it is hot even on the standby position. The power supply bottom face is very hot all the time. The thermal regulation aspects of the T2 have been for sure, deeply studied, and there is no need to say that it operates in pure Class A: would you expect something else from a preamp designed with the Nelson influence ??...

The standby position, although it offers an evident advantage in terms of muciality, has nevertheless not perfectly been studied regarding ergonomy: this standby position can only be activated from the remote control because there is no standby button on the T2. Consequently, you do need an operating remote control to use the T2...
As we are talking about the remote, it is also built like a tank: forget the today plastic remotes, this one is (very) heavy and robust !



The remote control


In the center of the T2 front face, there is a blue LCD display informing you on the input you are listening as well as the gain level (in dB). The (big) left button is the source selector, the right button is the volume control.There is also a (very small) button to reduce the lighting of the LCD or to totally switch it off.

It is important to note that, like the other state of the art preamps, the T2 does NOT use a potentiometer but an attenuator. This is a costly device that largely impacts the final price of the unit. When you adjust the volume, from the remote or by using the front face button, you ear the attenuator steps switching: this is a sort of mechanical "clic clic" noise, which is obviously not transmitted to the loudspeakers.

Sound performance analysis:

The T2 is a well known preamp in the Hi-Fi world and has been deeply compared with the other "state of the art" preamplifiers during his manufacturing period, particularly in the Stereophile US magazine in which it was regularly ranked at "Class A component" (for those who are not familiar with this Stereophile ranking, the "class A" means the best components available on the market).

Warning: the THRESHOLD T2 preamplifier is designed to be ON permanently: it do need more than a week to reach its sound balance and optimal definition. If a review or comparison is done before, it will not be representative of its performance and definition.

The THRESHOLD T2 has been deeply compared by Stereophile to the MARK LEVINSON n° 38S and MARK LEVINSON N° 380S, and by myself with the AUDIO RESEARCH SP6-B, SP-10 and PERREAUX SM3A preamps.

The Stereophile conclusion was that the T2 was better than the ML 38S by a large margin, and was inferior to the ML 380S, particularly in the high frequencies. More detail regarding this Stereophile review can be obtained on demand.

My personnal reviews and comparisons are detailed hereafter, and were performed with a THRESHOLD SA 3.9e amplifier and an ONKYO Grand Integra 2x200W (class B) power amp.

Compared with the AUDIO RESEARCH SP6-B preamp (tubes recently changed, so no pb on this side), the T2 is so superior that the SP6-B is simply ridiculous.... There is much more detail, no grain at all, more dynamics, more elegance, etc... The SP10 does not reach the T2 neither, but we did not have the opportunity to compare long enough to detail more on this.


Compared with the PERREAUX SM3, which is a very good and unknown preamp (it is better than the ARC SP6-B), the difference is again very important. The most surprising thing is how much the difference is big, as well as the nature of the difference. The T2 outperforms the SM3 and the SP6-B in every aspects, clearly demonstrating that it does not play in the same category than the 2 other preamps.

The 1st thing that I noticed was the elegance of the sound provided by the T2: I thought "damned, how can it performs so much better and offers so much refinement in the manner it plays ?".
The 2nd thing I noticed was: the silence between the notes; you get the impression that there is no noise at all between the notes and you can ear the silence... The notes are more articulated, with much more details, and far superior dynamics.
The 3rd thing, which is a well known caracteristic of the T2, is the quality of the bass reproduction: the oversized power supply clearly contributes to this aspect (not only), and the T2 offers very deep, rock solid, incredibily articulated bass response.
And then I concluded: "yes, no doubt, it is a Stereophile Class A preamp...".

The cons of this preamp ? well, difficult to say because I have not yet lessonned to a better one in *my* system: I plan to lesson to a MARK LEVINSON 380S that Stereophile estimated better, in order to know the differences between the both. Stereophile reported that the T2 high frequencies were not as good as the 380S ones, it is maybe true maybe not, but I do not have any concerns with my current high frequencies reporduction.

I also compared different cabling methods to estimate if the T2 prefers the RCA connections or the XLR ones.

Regarding the output:
-it seems that the T2 is not sensible as it is difficult to ear a difference between the RCA and XLR output: this test was done with a high quality Teflon insulated pure Silver cable using Eichmann Silver Bullet connectors, and the same cable with XLR connectors. I nevertheless believes that, in *my* system, the XLR output is, maybe, a little little better is terms of overall elegance (but I would not bet 10$­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­ on this).

Regarding the input:
-with high quality Teflon RCA cable using CARDAS RCA connectors, it seems that the T2 prefers the XLR inputs (compared to the same cable using XLR connectors). This may also comes from the XLR source output which is maybe better than the RCA one.

With the other pure silver modulation cable, Teflon insulated, that I have 2 sets of (one with the superb Eichmann Silver Bullet connectors and the same with XLR connectors) it seems that the T2 prefers the XLR inputs, but by a very very thin margin. This may show that the Eichmann Silver Bullet connectors are as good as they are said to be...

Edit 14th October, 2007: following some investigations and questions, it appears very difficult to make a universal difference: the final quality depends mainly on the source output quality: if your source is better with an RCA output, then use the RCA input of the T2...

Finally, I use only XLR connectors, from the source and to the power amp, but it is clear that the RCA inputs are also very good (if not equal).

Regarding the AC power cord:

This is an extremely important point: the T2 Power Supply is excellent and the T2 is a very detailled preamp (after its required 1 week ON period for reaching its optimal performance). Therefore, you can vastly improve its sonic performance by replacing the original power cord with a high-definition power cord. The improvement will be: more detailled, even less grain inn the high frequancy (!), more elegance, better high frequencies.

The final word is: the T2 is a great preamp that totally merits its "Class A Stereophile" ranking. More than 10 years after, it is still in the top of the preamps.

We nevertheless do not give our "5 stars, State of art" ranking because the components used inside mainly come from taïwan instead of Europe or USA, like it is the rule in the THRESHOLS SA serie amplifiers designed by Nelson PASS.

We also know that we can push it further, as far as the "state of the art" ranking, by upgrading it as described in the dedicated article, available here.

But it merits its "5 stars" ranking, particularly because it is incredibly good musicality. The price you have to pay for it actually is ridiculous compared the musicality you get from it  (generally around 2.200 - 2.300 US$­­­­­­­­­­­ or €,..., but it is difficult to find...). Nevertheless the relatively poor quality of the parts compared with the high original selling price, as well as the circuit complexity, rank it in the 5 stars category by a small margin...(whereas the upgraded version is a true bargain).




Article written by Nounours ("Nounours18200" on the Forum).

Creation date : 01/06/2009 @ 12:01
Last update : 09/11/2014 @ 20:45
Category : Threshold
Page read 18234 times

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Reactions to this article

Reaction #2 

by Nounours18200 23/08/2010 @ 21:16

Bonjour Perre981,
Pour faciliter les discussions, j'ai répondu à ta question sur notre Forum, ici: . N'hésites pas y poster tes futurs messages.

Reaction #1 

by perre981 19/08/2010 @ 09:31


Je viens de lire avec intérêt votre article concernant le T2.

Je bi-amplifie des Tannoy Canterbury 15+ST200 avec 2 Mac Intosh 240 de 61/62 tr bien restaurés( je n'ai d'ailleurs jamais entendu ces enceintes restituer la musique aussi bien après bon nombre d'essais d'amplis) J'ai le préampli Conrad Jonhson PV12 bien retubé( GE ). J'essaie un préampli ML 10 que j'ai en dépôt d'un ami. Il me semble que c'est mieux car on m'a toujours dit qu'avec les MC 240 il fallait un préampli très " droit " et très transparent. Qu'en pensez-vous pour orienter des recherches en ce sens ? ( ML,Treshold ou autres... )


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