Review: Bent Audio Tap Linestage


Category: Preamps

Before, I get to the details of reviewing the Bent Audio Tap Linestage, I first would like to give a context regarding what my linestage reference of the last three years has been in order to "set the stage" so this review would be the most helpful to the members reading it.

My reference over the last three years has been the Placette Audio Dual Mono Active Linestage. It replaced a ML-32 reference preamp in my system. I had auditioned six different preamps/linestages, half were tubed - half were solid state ranging in price from $6000.00 to $16000.00, until I finally heard the Placette Active in my system and found what I was looking for sonically. It offered, compared with the other pieces in my home auditions, the following sonic virtues:

1) No noise floor at all. Music just "floated" out of a totally black background.
2) A great soundstage, front to back - side to side, with the best center fill and layering I ever had in my system.
3) Precise microdynamics and details without being what I would call "dry" or "etched" at all.
4) Excellent extension on both the top and bottom with great slam in the lower bass.
5) Natural tone/timbres, very important to me because I listen almost totally to acoustic jazz.

Not bad stuff! However, being the curious audiophile that I am, I had read about a few new linestages that had come out the last couple of years and decided to listen to what some of the best designers were up to now. This time around I auditioned a highly regarded solid state,tubed, and transformer based units. Even though the solid state ant tubed pieces were almost twice as expensive as my Placette, and they have their virtues, I did not find them to better the Placette in the above mentioned areas. Different but not better for my ear's and personnal taste.

That's the context, now on to the review. The Bent Tap Linestage is the child of John Chapman and his company Bent Audio out of Canada. I would like to share John is one of the great gentleman/designers of high end gear and is a true pleasure to talk and to do business with. His pieces are purchased direct, with a 30 day trail period with full refund if one is completely not satisfied.

At this point in time there has been a full review on the Tap Linestage on POSTITIVE FEEDBACK ONLINE website by Bruce Kinch and on SIX MOONS website there is what they call a "pre-view", along with one of SIX MOONS reviewers, Les Turoczi, who considers the Tap Linestage one of the "favorite discoveries of 2006" and has made it his new reference linestage in his system.

The above mentioned reviews, along with information on the Bent Audio website, will provide excellent background information on the topic of passive preamps/linestages and specificly on the issue of transformer based passives compared to Vishay resister based approachs. By the way, the Placette Active is a Buffered Vishay based passive linestage that gives no gain, but eliminates any concerns with impedance matching the front end with the down stream amps.

I never get into lengthy details regarding engineering or parts, that is all provided by the Bent Audio website, however I always comment on build quality and looks before I get to the the most important part the sonic performance. The Tap Linestage has a "cool modern" look to it, but it will never be the "eye candy" that my Pass Labs or Accustic Arts pieces are to me. The front has angled sides and sits atop a 1" slab of clear acrylic which has been routed out to securely mount the twin transformers. Inside high quality Arlon circuit boards, ribbon cables, and custom OCC copper wire sourced from Neotech speak highly of the construction of this piece.

Now, to the most important part of any review, the sonic performance of the piece being evaluated. In the following areas the Tap and PLacette active were, at least for me in my system, indistinguishable:
1) Total black background, no noise floor, music just "oozes" out of the system.
2) Both provide the best soundstage and layering of any linestage I have ever had in my system.
3)Macrodynamics are present and powerful, but intergrated in the overall "fabric" of the music.

Were the two linestages start to part sonic company is revolving around to key sonic areas, tone/timbres and image density of players in the sound stage.

I find that the Tap to be slightly "warmer/fuller" then the Placette Active in overall timbres, what many listeners would refer to as the "magic of tubes", mind you, not "fat/euphonic" but more "velvety" then the "silkyness" of the Placette. It reminded me when I went from an Edge NL-10 to a pair of Pass Labs XA-100's, both great amps, but I found the XA-100's to be subtly more what I call "organic/musical". Another verbal stab at it would be to say that the Placette Active has "razor sharp" leading edges and the Tap is a little more "rounded off" but has more body and decay then the Placette Active.
The Placette Active never sounds "etched, dry, or overly analytical, but a little less "sweet" then the Tap. They both offer beautiful sonic pictures and what you would like would be very much decided by your personnal taste and what type of system synergy you would end up with in your rig.

The other sonic difference that I noticed was in the area of image density. The Tap kicked it up a notch in comparsion to the Placette Active regarding the density of images, not the size or air around the individual players, but how "real" they sounded in the stage. Again, both linestages are quite terrific regading this sonic aspect, but the Tap gives more in this area then the Placette Active.

So, is there a winner or loser between this linestages, I don't think so, there both reference level in their performance. As I always say at this level of gear it comes down to personnal taste and system synergy. There's always very small but real differences in gear, but the final voicing of any system finally comes done to matching this tiny sonic bits together to get what we are listening for in the pleasure of the music we care about.

The Bent Tap is my new reference linestage for the reasons stated above. Both the Tap and Placette Active are great performers, terrific bargains for what they sell for, the Tap $3000.00, the Placette Active $5000.00, when you think they compete with any linestage on the market today and both John Chapman and Guy Hammel are great gentleman to work with, you might put both on your audition list if your seeking out a new linestage. Which one you would like better truly would come down to personnal taste/system synergy, so really won't know till your try it in the context of your own rig.
teajay
The output impedance varies depending on the detent selected. If I'm not mistaken the output should be around 1/4 the sources input impedance...So if your source is 100 ohms the rough guess is 25 Ohms on the output of the TAP. But again it varies depending on the detent.

The difference you hear may have more to do with the input sensitivty of each amplifier..I think? One may need only 1 volt to full power the other 2 volts. So your detent settings will be different for each amplifier. This will also change the voltage and impedance output of the TVC.
Teacherman, my Tap's transformers are wound with copper wire, not silver. When I was discussing this topic with John Chapman, because I was curious regarding the copper vs. silver sonic differences regardless of the price difference, he had experimented with both and came to the conclusion, in a blindfold, that the sonic signatures were so close he could not distinguish one from the other. He decided that the extra cost of silver wire was not worth the cost sonicly to the average costumer. I believe he will wind silver transformers as a special order, if someone wants it that way.

As I stated in my review the Placette Active offered more razor sharp leading edges then the Bent Tap, however I have never listened to a Transformer based linestage with silver transformers, so you might know alot more regarding the sonic difference(s) between copper/silver based passives. Finally, I find it quite interesting you got different sonic effects with different isolation devices, when I found no difference at all in my system.
Dbld, I use a off brand, don't remember the manufacturer's name, that cost around $500.00 per rack that have three shelves. The frame is composed of very thick steel posts filled with sand and the shelves are medium density particle broad. Each shelve sits on steel pinpoints at it's four corners. The Tap sits on the top shelve that rests on the longest spikes of all, a full inch. So, I think the Tap is well protected from acoustic vibration in my system.
I found the following information, gained by further reading and discussions with DIYer's, very interesting regarding why the transformers in different transformer based passives offer different sonic signatures.

1) "To Pot or not to Pot" that is the question! In the Tap, John Chapman does not use potted transformers. Unlike the Music First passive that uses Mu-Metal canisters, the Tap's transformers are not encased or "potted" but are mounted by a pair of aluminum brackets that sandwich the core laminations and bolt to the bottom plate. Not only does this offer better vibration control, many believe that unpotted transformers have a overall sonic signature that is different then potted transformers.

2) That the type of expoxy used to seal the transformers, I guess different kinds can be used, also effects the sonics of the different transformers.

One of my discussions was with an electrical engineer who builds his own transformer based linestages and is always experiementing with different expoxies/resins and different types of metal/wood enclosures for his devices and swears that each factor can dramatically influence the overall sonic signature of the transformers. So, these among other factors might explain why you get subtle sonic differences between the passives that all use the S&B transformers.