AC Filtering, Grounding Boxes, Linear PSU and Balanced Power.

[YashN]

I hope this guy isn't floating his secondary...

 

Looks like he's welding his hand. Whatever 'floats his boat'.

[YashN]

One and a half has written that he uses a 2KVA isolation transformer ahead of his Equi-Tech balanced transformer, but laments that it offers a greater capacity than is ideal, suggesting that as the VA rating of an isolation transformer rises relative to the load it serves, the impedance is reduced and you start to lose the current-smoothing benefits. I'm paraphrasing, but he suggests that going much higher than 2x the load you will lose this benefit.

 

Look for Russ57 on audioasylum and the tweaks section, where he writes on getting a big transformer and then de-rate it for use. 1.5 probably didn't spend a lot of time researching about proper transformers to use or how to use them.

 

2) Should I purchase isolation transformers that float the secondary or isolation transformers that ground the secondary's neutral?

This leaves me in a quandary because reducing common mode noise by grounding the neutral of the secondary coil seems to be something every audiophile would want, and yet, floating the secondary is what most audiophiles seem to prefer, claiming that doing so reduces noise from the mains.

 

Imitche has written (joining what seems to be a majority consensus) that even though floating the secondary comes at the expense of no longer enjoying common mode noise rejection, there are many audible benefits that outweigh the loss of common mode noise rejection.

 

The differing opinions are interesting. The way I'd approach it if I could would be to test with two iso transformers, one with float and another one without, listen for the auditory changes with a cheap component, e.g. an old CD player.

 

If the benefits of the float do seem something to pursue in a more permanent manner, I'd continue to research for a way of making it safe for the end-user (if at all possible). If the results are close, you're safe not floating anything.

[YashN]

Further research brought me once again back to Jon Risch over at AA. He's awesome.

 

Look into this post - Super Quick & Dirty Digital Isolation Transformer - which contains several URLs, the first of which was his initial post about an easy DIY isolation transformer for digital components (at the time, the inmates' focus was to use this with CDPs).

 

Here's a couple of schematics by Steve Eddy (one of the URLs):

 

 

This looks doable to me, provided you get some transformers that step-down to no less than 25VAC if I remember Jon's advice correctly. Not sure I have those in my salvage box though. Buying some new ones shouldn't be too expensive OTOH.

 

Then come the questions (not sure yet) about how I could use it in combination with the filter box:

 

A: [AC Mains] -> [Digital Iso] -> [Filter Line] -> [Component]

 

or

 

B: [AC Mains] -> [Filter Line] -> [Digital Iso] -> [Component]

 

and planning ahead, the best way to combine all this in turn with a Balanced Power transformer:

 

[AC Mains] -> [balanced Power] -> [A] or

 

or even:

 

[AC Mains] -> [Digital Iso] -> [balanced Power] -> [A] or

[YashN]

A recent review of the Bryston Isolation Transformer BIT-15 (another adopter of Plitron technology):

Bryston has taken all of these factors into consideration in the design of their Bryston Isolation Transformer (BIT) and cites the following advantages:

 

• Very low impedance and high current for power amplifiers. The proprietary transformer uses technology developed by Plitron Manufacturing. This enables the handling of high instantaneous peaks that an amplifier may need and that cannot be managed straight out of the wall outlet.
  
• Surge suppression that exceeds the performance of a metal-oxide varistor (MOV). MOVs can allow up to several hundred volts to reach components while BIT devices clamp voltage onset around 2V above nominal voltage, offering far better protection against damage. MOVs also “shunt” to ground, resulting in higher ground voltage that affects both audio and video signals. MOVs are “sacrificial,” meaning that they eventually wear out and fail.
  
• BIT toroidal transformers isolate devices from outside power grids. External noise sources like refrigerator motors or lights can be easily rejected in ranges from 2KHz to 1MHz as opposed to typical transformer-based isolation devices that do not kick in until 10KHz.
  
• BIT devices use “LONO” (Low Noise) transformer design. This eliminates audible transformer noise regardless of line conditions, DC offset and overvoltage.
  
• BIT devices use “NBT” (Narrow Bandwidth Technology.) NBT attenuates differential and common-mode noise at a lower corner frequency (2KHz), eliminating the need for an external filter.
  

 

 

It appears people making and optimising their home-theater have more experience than audiophiles with these types of equipment, judging by my searches bringing me often to those types of forum.

[YashN]

Not sure I posted this before but enjoythemusic has a cool comparative review of several well-known outlets like the Furutech and the Oyaide, as well as less expensive, or less known ones.

[YashN]

Parttimeaudiophile has a review of the Silver Circle Audio Tchaik 6.

 

There’s a honking-big (and completely silent) toroidal transformer set inside a 12-gauge powdered-coated steel chassis, along with five fancy new “wave stabilizer” modules from High Fidelity Cables‘ Rick Schultz. I have no idea what these stabilizer things are or what it is they actually do, other than the obvious — they’re magnetic and they reduce noise on the current being delivered by the system. There are two on the input side (positive and negative), two on the output side, and one on the ground. Super-dense Terrastone footers from edenSound provide the mechanical grounding/isolation. Four pairs of Furutech GT- receptacles provide eight SOTA plugs for all your gear, and a brand-new top-of-the-line Vesuvius II power cord with updated/upgraded Furutech connectors rounds out the package.

 

I'm not too sure what to make of the mention of Rick Schultz and his magnetic wave stabilizer modules. Several years back, he generated quite a lot of controversy around his power cable, and this had such a backlash that he moved away from the scene for a while. The gist of the issue: safety...

[YashN]

There is a treasure trove of info over at Mike Holt's website, where he focuses on Electrical Code.

 

- PDF about Code requirements for GFCIs

 

- GFCIs - How They Work

There is a longer similar article somewhere on his site and dated '99, so for more current Code info, this needs to be updated.

 

There's a lot more interesting info around if you look.

 

How GFCI'S WORK IN E & M Magazine.

 

 

Video:

 

[video=youtube;pObsSoI4-yE]

[YashN]

Over at Audiocircle, there is a sub-section on power-conditioning with a lot of posts.

 

There is an interesting thread about someone passing his DIY distribution box through the mail for other members to try and discern differences between outlets like the Tesla, Maestro and Hubbell.

[YashN]

I'm not using balanced power, so I'm going to assume Russ57 would advise me to start with an isolation transformer rated at twice the total VA needed by all of downstream gear, but with smaller isolation transformers inserted ahead of each digital component. And I will assume he would say that each of the individual isolation transformers should offer twice the rating of the component served.

 

I'm not sure for the case of the iso, as I've mostly seen Russ57 talk of de-rating with his Balanced one. Perhaps it applies as well. You seem to have done some research and found other good things by him. Good on you for doing that.

 

Jon Risch has more on the iso transformers: he also advises smaller ones for the digital components.

 

Bear in mind that at the time on AA, these pursuits were for a system where the CDP reigned king as a digital source. Over here, at CA, we need to transpose that to the computer as digital source, and check power rating.

 

You've been doing your homework YashN and I very much appreciate your having introduced me to Russ57's writings!

 

You too, man, glad you find these interesting. I am mainly gathering info to further my understanding and those interested so that when I implement I get good results. So far, I have obtained great results from my DIY (that you can see in my sig).

 

And Superdad is onto something, having put "smallish" isolation transformers in front of each of his source components.

 

Jon advised the same thing over at AA. I think I may have come across two or three different overall arrangements, so I have yet to find the best one.

 

Unfortunately, I'm incapable of building my own gear, which begs the question: Where can I find a ready-to-use 110V 30VA isolation transformer with floating secondary (as the individual transformer for my max. 15VA DAC) and a ready-to-use 110V 60VA isolation transformer with floating secondary (as the individual transformer for my max. 30VA headphone amplifier)?

 

The B&K Precision 1604A is about the smallest ready-to-use isolation transformer I can find that's documented as having a floated secondary.

 

Good question. I know that Jon initially recommended some easy to find transformers from Radio-Shack but later advised on better ones or some with a different architecture.

 

It would be worth it to get updated info. I also like the little transformer building blocks that jabbr (if i'm not mistaken) posted about earlier.

 

Maybe John S. could chime in.

 

I have found a few transformers in my salvage box, and I think a couple of them could do the trick for an iso transformer for the computer. I find it hard to find datasheets for them though.

[YashN]

The article from Ross B pulls apart a GFCI and concludes, gee no wonder they don't sound good, they are made of thin PCB tracks and undersized contacts.

 

Then Russ fits white receptacles on a balanced supply, I'm not in the US, but the outlets need to be orange, labelled and the GFCI put back.

 

You got your facts crooked and it's not the first time you do that and unjustly accuse people. You are talking about Glen B. and not Russ, who is Russ57 from AA, whom advice you could have followed to get good results with your DIY balanced power implementation.

[YashN]

That applies to Australia, but surprisingly, not New Zealand.

240VAC is far less forgiving than the U.S. mains .

 

I was blasted by the current from a 240V outlet as a quadrupedally mobile entity (a baby). I had found a hairpin under the bed, took it and moved to a wall where I found two round holes. My thinking at the time (yes, I do remember that), was that the house was broken, so I inserted the hairpin in the outlet as I wanted to repair the house.

 

The skin of my hand turned black. It felt like somebody at the other end of the house was furiously shaking my hand.

 

It wasn't painful.

 

(Don't do this)

[YashN]

My (eager to be corrected) understanding at the moment is that the grounded neutral on the secondary of the Tripp-Lite is500 will provide common mode noise rejection that I would forfeit if I modified the is500 to float its secondary. The downstream B&K Precision 1604A, with its factory-designed floating secondary, will provide normal mode noise rejection that's not available with the grounded secondary of the is500.

 

My USB source is an iPad 3 > CCK > Supra cable, so there's no chance of a ground loop there either, as the iPad 3 is battery-powered when playing.

 

The only other cables leaving the DAC are the RCA interconnects to my headphone amp, but I can't imagine a need to buy a two-channel RCA (line level) isolation transformer (like the Jensen IsoMax CI-2RR), because there's no path for ground loop currents to flow, when both the Regen and the iPad 3 are powered by independent batteries, and the DAC itself is powered by the floating secondary of a B&K 1604A.

 

What do you think? :-)

 

I think you're far ahead of me when it comes to transformers. I can only access what's in my salvage box and perhaps a couple of other boxes that I can extract the transformers from.

 

I may ask one of the electricians nearby who works for a bar owner friend of mine if he can source me one for additional experiments. Certainly, if the owner here doesn't drop by often, I can get the feedback of this electrician (for dedicated lines, transformers, safety, etc...)

 

As for your audio chain, I think you assessed it properly, the iso could be useful with a CDP or computer.

 

If the high ratio of transformer capacity to load is an issue, I might lose some benefits (current-smoothing?) that I wouldn't lose if I could get the transformer ratings down to 2x the load, but I'll start with this setup and see what I can hear.

 

I believe Jon mentioned leakage currents for the two transformers linked as an iso, so that's why he advised to go not lower than 25VAC after step-down. Maybe asking Russ could be helpful.

 

In any case, the USB Regen has taught me (like nothing else) that digital noise is insidious for how easily it can be overlooked. I've awakened to the fact that I should never assume "I have arrived" in terms of noise reduction and thus, the old adage simply does not apply: "Don't fix what ain't broken." Nope. I want to keep right on "fixin' what ain't broken" (wallet permitting) until the fixes prove themselves useless.

 

It's pervasive in a digital setup: much of the noise is inherent to how the digital circuits function.

 

Furthermore, many of the implementations were laid out at a time when high frequency EMI/RFI didn't have the profile that we have today, so, IMO, much of what used to be good has to be completely re-evaluated in the current situation.

 

It's been my experience that every time someone said 'it won't make any difference', it turned out they had limited theoretical knowledge coupled with a reluctance to do their own tests.

 

Nearly every single thing I tested myself made a big difference, for the better. The DIY items in my sig is testament to that. I had started with acoustic panels, so that was rather cool, but the really eye-opening build was my DIY USB cable.

 

Now that the Regen is out, let's see the nay-sayers still argue around the 'bits are bits' line.

 

Within my own experiments and experience and understanding of systems engineering, and now with audiophile music reproduction, bit-perfection is necessary but far from sufficient.

 

There are too many hidden things in computer operation linked to audio to list here, but the thread here on CA about DRAM does provide a lot of info.

 

Whenever you want to try something new and hear nay-sayers and trolls it's because they fear you get results they can't get, can't hear, or hadn't thought about.

 

The cognitive dissonance of that is too large for them to deal with it, and so they hide their own inadequacy behind their keyboards.

 

Your choice of a tablet for source is interesting in the respect of the contents of the DRAM thread mentioned above: we had discussed the use of a very small Android/ARMH powered device for that. One of the many important things we discussed in that thread (PeterSt, Miska, John Swenson, sbgk) was the issue of power spikes and concomitant ground plane noise affecting SQ.

 

Nowadays, I'd rather continue on my tests rather than argue with the nay-sayers - they're too far behind for it to be useful and it's usually a waste of precious time when the enjoyment of music by my girlfriend is what really mostly drives me.

 

Let us know the outcomes of your experiments too!

[YashN]

A few resources for transformers found on an Amazon page by a reviewer:

 

You may also alternatively reliably isolate your equipment completely from the power line using a more expensive and very heavy isolation transformer. By using an isolation transformer, the ground noise voltage will now appear between the transformer windings and not circuit input. The noise coupling is primarily a function of parasitic capacitance between the transformer windings and can be reduced by placing a shield between the windings.

 

* Tripp Lite IS250 250W Isolation Transformer 2 outlet 6ft Cord

 

* Tripp Lite IS1000 1000W Isolation Transformer 4 outlet 6ft Cord

 

Typical ground loop problems can also be solved using 'audio' isolation transformers inserted into the audio lines.

 

* Ground Loop Isolator - Auto

 

* ART DTI Hum Eliminator

 

* ART CleanBox II Passive Hum Eliminator

 

* Behringer HD400 2-Channel Hum Destroyer

 

Optical coupling can also be used to eliminate the potential for ground loops.

 

* Turtle Beach Audio Advantage Micro II USB Analog & Digital Audio Adapter

 

* Digital Coax & Optical Toslink to Analog Audio Converter

 

A noise gate can also be used to reduce hum. A noise gate doesn't let any sound through the gate unless the sound has a signal level which is higher than the set gate threshold value. If the problematic hum is very faint a noise gate can make it much less annoying. When you set the noise gate threshold so that the gate does not pass any signal when there is silence in the source music the hum is not added to the main mix. When the sound level rises above the noise gate's trigger setting the humming is difficult to notice due to masking by the louder musical passages.

 

* Behringer MDX1600 2-Channel Expander/Gate/Compressor/ Peak Limiter

 

* DBX 266XL Dual Compressor Gate

 

Some DI (Direct Input) boxes employ the use of ground loop eliminating impedance matching audio isolation transformers. Such boxes allow mixing unbalanced and balanced audio lines.

 

* Sidekick Passive Direct Box

 

* Ebtech Hum Eliminator

 

* Ebtech HE-2-XLR Hum Eliminator 2-Channel Box with XLR Jacks

[YashN]

Info from Apple regarding isolation:

 

There are several techniques for minimizing or eliminating ground loop-based interference:

 

1. Reduce the amplification of the noise relative to the signal through appropriate "gain staging." This technique involves setting the gain as low as possible in the section where the noise is coupling in, and compensating with higher gains in other sections. For instance, if the ground loop is created by a pair of powered monitor speakers, the interference can be minimized by lowering the gain control on the speakers themselves, and raising the gain in any previous stages. Remember not to turn any stage up too far, so it doesn't induce clipping.
   
2. Reduce the potential difference between currents by plugging the computer and all attached peripherals into outlets which are as close together as possible.
   
3. Eliminate the path(s) of the current by using isolation transformers or by breaking the shield connections on the audio cables going into the computer. The most dramatic improvements are generally seen with this technique, as it essentially eliminates the offending currents, which are carried on the shields of cables connecting to analog audio equipment. If you use a balanced (XLR) interconnect, isolate the current by breaking the shield (pin 1) connection. Use a cable designed without this connection or a shield isolator adapter. If you use an unbalanced (RCA or 3.5mm) audio connection, use an isolation transformer. The next section of the article lists resources for these cables.
   

The goal in reducing ground loop noise is to break any connections between the shields of cables connected to the computer and any analog audio equipment which in turn shorts the shield to the "green wire" ground of its power cord. You can use a simple ohmmeter, available from Radio Shack or other electronics stores, to identify where the unwanted ground connections exist.

 

 

and:

 

Isolation Transformers for Balanced and Unbalanced Inputs and Outputs

There are two types of inputs and outputs. Professional equipment uses balanced inputs and outputs. Consumer equipment uses unbalanced inputs.

 

Balanced

Professional multimedia equipment, with balanced inputs, uses either XLR or 1/4-inch TRS (tip-ring-sleeve) connectors. These consist of three wires or pins for each channel. Two of the wires contain an equal-voltage audio signal, while the third wire contains the ground. These specialized connectors are most often found on professional USB audio interfaces, FireWire audio interfaces, mixers, and amplifiers.

 

Unbalanced

Most consumer audio and video equipment has unbalanced inputs that use either coaxial (RCA) connectors or 3.5 mm connectors. A coaxial cable has two wires. One wire carries the audio signal, and the other is the shield or ground wire, which carries the ground. This means that a stereo signal requires two cables, one for right and one for left. 3.5 mm connectors usually contain a pair of wires and one shield, providing left and right stereo plus ground.

 

Apple computers are designed to integrate with existing consumer multimedia equipment, including most stereo equipment, televisions, VCRs, and portable speakers. Consequently, Apple computers use unbalanced inputs and outputs. If you are connecting your computer's sound output port to another piece of equipment with unbalanced inputs, consider using an unbalanced isolation transformer.

 

 

Unbalanced to Balanced

For connecting unbalanced output (such as your computer sound output port) to a balanced professional input, a third type of isolation transformer is used. This isolation transformer has unbalanced inputs and balanced outputs.

[YashN]

My (eager to be corrected) understanding at the moment is that the grounded neutral on the secondary of the Tripp-Lite is500 will provide common mode noise rejection that I would forfeit if I modified the is500 to float its secondary.

 

The Amazon description of its smaller brother indeed mentions the same thing.

[YashN]

Thanks for all of your feedback, YashN. Not owning a balanced power solution, myself, I cannot say that I've done any testing with them, but I'm becoming increasingly convinced from a lot of reading, that properly arranged isolation transformers can do a lot more for noise reduction than just preventing ground loops.

 

Judging from the descriptions of the Tripp Lite devices, they also isolate neutral and live, and additionally build a Faraday cage around everything.

 

I think there are degrees of improvement with all these solutions, and some are more fundamental as others, meaning that I think that given the choice, I'd rather do a dedicated line and balanced power rather than upstream optimisations.

 

In that case, the further upstream optimisations may have less results.

 

All can also be combined to a great effect.

[YashN]

Today, I decided to try the chassis grounding again, but this time I removed the connection at the amp's phono stage ground and instead used a chassis screw. Wired it up as before between the amp, the iFi and the iMac.

 

No doubt the larger, bigger soundstage and micro-details are back, confirmed by my girlfriend.

 

On measuring, I still find some voltage difference readings between two components but they are lower.

 

I was thinking of actually connecting the chassis wire to one mains ground on my filter box, but have yet to try that. This is because I am not sure yet the iMac chassis is fully grounded. I have seen many people report a lot of noise in the Mac because of how the circuit ground is connected, especially in a recording environment.

[YashN]

A great article by David Davenport on 'Audio Component Grounding and Interconnection'.

 

It's a great read with illustrations of the various cases throughout and references a lot of the good folks we have come to know and appreciate in this thread, like Brown, Whitlock, Morrison, Muncy and Ott.

 

It also has several sections on transformers and ground isolation.

 

[YashN]

RANE has a handy text with a chart and accompanying Sound System Interconnection solutions for solving some of the noise problems we have.

 

 

The advice here seems good for my system (RCA-to-RCA unbalanced):

 

A common solution to these noisy hum and buzz problems involves disconnecting one end of the shield, even though one can not buy off-the-shelf cables with the shield disconnected at one end. The best end to disconnect is the receiving end. If one end of the shield is disconnected, the noisy hum current stops flowing and away goes the hum -- but only at low frequencies. A ground-sending-end-only shield connection minimizes the possibility of high frequency (radio) interference since it prevents the shield from acting as an antenna to the next input. Many reduce this potential RF interference by providing an RF path through a small capacitor (0.1 or 0.01 microfarad ceramic disc) connected from the lifted end of the shield to the chassis. (This is referred to as the "hybrid shield termination" where the sending end is bonded to the chassis and the receiving end is capacitively coupled. See Neutrik's EMC-XLR for example.) The fact that many modern day installers still follow this one-end-only rule with consistent success indicates this and other acceptable solutions to RF issues exist, though the increasing use of digital and wireless technology greatly increases the possibility of future RF problems.

 

My own future interconnect design will be of this form.

[YashN]

This one also from RANE is about Grounding and Shielding Audio Devices.

 

This chart shows all available combinations and their quality, best is upper left, worst is lower right:

 

[YashN]

SCIN: Shield Current Induced Noise

 

 

Neil’s research, conducted only at audio frequen-cies, showed that foil/drain-shielded cables had the worst SCIN performance, while braid-shielded cables were about 30 dB better. My research shows that braid-shielded cables maintain this advantage to at least 2 MHz, but gradually begin to lose it above that frequency. My more recent work shows that the braid cables are still better to at least 7 MHz and about the same as foil/drain construction at 14 MHz. By 28 MHz, the foil/drain cables are better.

 

1. Cable BDQ (a Gepco product) exhibited excellent SCIN performance. A short sample (all I had) of another well known quad cable did not measure nearly as well. [Quad construction is not without its drawbacks -- star quad cables have far greater capacitance between conductors than conventional cables. Dennis Bohn has observed that placing an excessive capacitive load on the output stages of microphones and other audio equipment causes distortion of high frequency transients.]
   

 

 

 

1. Braid shields are far superior to foil shields with respect to their ability to reject interference below 4 MHz.
   

 

 

 

1. As we will learn next, a foil/braid shield is good at all frequencies!
   

 

 

 

1. SCIN will cause RF to be coupled to the signal pair, so audio equipment must include good low-pass filtering to reject it.
   

 

 

 

1. Extending the bandwidth of audio gear much beyond 100 kHz in a quest for ideal phase response is an invitation to RF interference.
   

 

And finally:

 

So, to summarize, the “right” way to terminate balanced cable, whether for audio or data, is to maintain the twisting as carefully as possible right to the point where it enters equipment (ideally there should be “zero length” of untwisted cable). If the shield is to be terminated, there should be either a concentric connection or the shortest possible pigtail, and it should go straight to the shielding enclosure of the equipment. If the connection is needed to shield against VHF RF but needs to be interrupted at lower frequencies to prevent shield current, a capacitor should be used in series with the shield connection (also with very short leads or a concentric connection), and only at the receive end.

[YashN]

That is a problem with most opamps, and the main reason for use of a low value resistor (typically 100 ohms ) in series with their output.

 

Or do as Lukasz Fikusz used to do, and rip out complete output circuits (including their opamps and capacitors) from old CD players and replace them with a tube implementation (hence the name of Lampizator).

[YashN]

I have a small set of 'audiophile' test CDs that I use to assess some of the changes in my gear. As usual, I am fond of up-converting these to DSD128.

 

The other day I was checking out the tracks to make some space for my other rips. I removed a few from a Focal CD. I listened to all 3 Dali CDs I have and deleted only 1 track in all these CDs, so if you want some great-sounding records (and quite varied too), check the Dali CD Volumes 1 to 3.

[YashN]

Were ALL the capacitors in the signal path of his designs removed too ?

 

Not sure, but he has a wicked sense of humour, so it's worthwhile to read his old archived posts!

[YashN]

I am well aware of that, but it's simply replacing with a more euphonic form of distortion ! (smile)

 

But no distortion like in some SS amps

 

If you heard my SS amp, you'd love it.

 

But if you heard my Tube amp, you'd love it even more.

 

Were ALL the capacitors in the signal path of his designs removed too ?

 

See Snip It - Modifications for beginners

 

The purpose of shunting the signal to the ground just before output is that it shall ground (kill) high frequencies which are trebles, midrange upper harmonics, and some noises too.

The idea behind it was that the designers were forced to play the SPECS game. Every CD in the 80-ties and 90-ties was being compared to the others by specs. And because the spec of CD - when it was introduced back in 1982 - categories were derived from the cassette, the LP, the tuner and the reel to reel, they were quoting signal to noise ratio (S/N), wow and flutter, and dynamic range. All completely meaningless when applied to CD. But to be ABSOLUTELY SURE that the CD does not produce ANY noise, they sacrified the trebles.

I mean - the CD was supposed to be PERFECT as compared to noisy LP and tuner and cassette. So IT COULD NOT HISS, NO MATTER WHAT !

Nobody blamed these CD players for having no trebles and no "air", but if it hissed with ear to the tweeter - boooooo! That was a no-no. No good for CD !!!!

 

Anyway, we can now call these engineers names like morons, idiots, audio-terrorists - enough said. What we don't want is to spread hatered, we want to snip these caps out and enjoy for the first time the REALLY OPEN SOUND.

One - two - three - SNIP!