@atmasphere - If the input of the next component is balanced and not referenced to ground (e.g. transformer coupled), I don't understand why it is necessary to decouple the output in the source component from any ground reference to achieve the full benefits of balanced connections. Can you please help me understand. Thanks.
300b lovers
I have been an owner of Don Sachs gear since he began, and he modified all my HK Citation gear before he came out with his own creations. I bought a Willsenton 300b integrated amp and was smitten with the sound of it, inexpensive as it is. Don told me that he was designing a 300b amp with the legendary Lynn Olson and lo and behold, I got one of his early pair of pre-production mono-blocks recently, driving Spatial Audio M5 Triode Masters.
Now with a week on the amp, I am eager to say that these 300b amps are simply sensational, creating a sound that brings the musicians right into my listening room with a palpable presence. They create the most open vidid presentation to the music -- they are neither warm nor cool, just uncannily true to the source of the music. They replace his excellent Kootai KT88 which I was dubious about being bettered by anything, but these amps are just outstanding. Don is nearing production of a successor to his highly regard DS2 preamp, which also will have a unique circuitry to mate with his 300b monos via XLR connections. Don explained the sonic benefits of this design and it went over my head, but clearly these designs are well though out.. my ears confirm it.
I have been an audiophile for nearly 50 years having had a boatload of electronics during that time, but I personally have never heard such a realistic presentation to my music as I am hearing with these 300b monos in my system. 300b tubes lend themselves to realistic music reproduction as my Willsenton 300b integrated amps informed me, but Don's 300b amps are in a entirely different realm. Of course, 300b amps favor efficient speakers so carefully component matching is paramount.
Don is working out a business arrangement to have his electronics built by an American audio firm so they will soon be more widely available to the public. Don will be attending the Seattle Audio Show in June in the Spatial Audio room where the speakers will be driven by his 300b monos and his preamp, with digital conversion with the outstanding Lampizator Pacific tube DAC. I will be there to hear what I expect to be an outstanding sonic presentation.
To allay any questions about the cost of Don's 300b mono, I do not have an answer.
- ...
- 874 posts total
@jaytor Part of the issue driving interconnect cables is how the signal travels in the cable. When the shield is part of that connection, its more likely to pick up noise and the actual construction of the cable (what sort of insulation it uses and so on) becomes more critical. That shield is connected to chassis ground at the input of whatever is being driven- so now you also have the possibility of a ground loop too. So when the source is referencing ground, such as a pair of single-ended outputs, one of which is out of phase with the other, you have a problem where the ground circuit return is active in the shield of the cable. Suddenly the dielectric in the cable is playing a role that it did not when the shield was only used for shielding with no signal on it. It is precisely this problem which is why there are 'high end audio' balanced line cables now that might cost up to $1000/foot or more (put another way, most 'balanced outputs' on 'high end audio' equipment actually references ground as if the designers were not aware of the balanced line standard)! If the connection is done properly, you won't be hearing the sort of differences between cables that might convince someone (who might have a touch of audiophile nervousa) to spend that $1000/foot. I'm saying that an inexpensive cable can sound just as good in every way. The proof of this is the vast number of recordings that were made in exactly this way- proper balanced outputs and inputs. Its part of why you could have 150 feet or more of interconnect cable between a microphone and the input of the tape recorder in 1958, nearly 20 years before Robert Fulton showed off his first 'high end audio interconnect' cable, yet the resulting recording just gets better and better as you improve your system's ability to winnow more information out of that recording. That can only happen if the cables used to make that recording are absolutely transparent! Put simply, you have to dot your 'i's and cross your 't's if you want this system to work properly. But let's look a bit closer at that balanced source that references ground. It may well be rack mounted in a relay rack and through that rack its chassis is grounded to every other bit of equipment in the rack or maybe even in the studio. Some of that equipment might be on the input side or the output side. So a ground loop could easily be introduced! You might think that because you're not using a 7' tall steel relay rack at home that you won't have that problem, but keep in mind that the equipment is also grounded into the wall. That's where you get in trouble: you must be sure that ground is ignored with both inputs and outputs; that ground is only used for shielding in cables and never for any kind of signal ground! If you don't do this, the benefit of balanced operation is eroded. It was designed so that exotic cables aren't needed and grounding issues are eliminated. Think about the advantage of having cables that sound as good as the best out there price no object, but not having to pay that price- for all the interconnects in your system, you might have only a few hundred dollars invested at the most, rather than $1000s or $10,000s. And they don't go out of date or any such thing... |
@atmasphere - makes sense. Thanks for the detailed explanation. |
That’s a quite confounding claim. What components using op-amps do you find objectionable? There are many excellent differentially balanced components that use op amp circuits, including all of the ARC Ref series preamps and amplifiers. Many people consider that a better approach than transformer-coupled circuits.
|
Due to package heat-dissipation limitations, most op-amps operate in Class AB. Now, they have a stupendous amount of feedback, and it takes a difficult load to excite the AB transition, but it’s still there. Speed is the friend of op-amps, so the high slew rate versions (more than 20V/uSec) often sound cleaner and smoother than the slower versions. It is difficult to build a discrete solid-state circuit with distortion specs that exceed an integrated circuit, but it can be done, and they are often seen in the pro recording studio world. These do operate in Class A, and that is always mentioned in the sales literature. I'm a bit surprised that ARC uses op-amps in their "Reference" series. Why not just buy Topping or SMSL and get even better performance, or if you insist on made-in-America, Benchmark, who live up to their name in performance standards? Why buy an high-end audiophile component, with audiophile pricing, made from off-the-shelf $5 parts. What's the point? I don't see the value proposition. Now, if there are a zillion discrete transistors, and it does 1000V/uSec and delivers 500mA mA into a 300 pF load, that's insane, but still in the realm of engineering possibility. Tube gear costs a lot because transformers and vacuum tubes are inherently labor-intensive, and the parts are not inserted on circuit boards with pick-and-place machines. I'm one of those madmen who think zero-feedback circuits are interesting, and I like tubes. Nelson Pass is your man if you like zero-feedback JFET/bipolar transistor circuits. If you are more sensible, read ASR reviews, ignore the comments section, ignore the single-dimension SINAD number, and look at the noise floor of the multitone IM distortion graphs. That is the true wideband IM distortion, and multitone is the most severe test of the entire circuit. The Shenzen group of manufacturers have some really good engineers, and it shows in the IM distortion measurement. From what I can see, Bruno Putzey and the Shenzen guys are at the top of the game, if specs are at top of the list. They also know how to "tune" a power supply to get a subjective result. |
- 874 posts total