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Not all balanced inputs a...
Forum: Issues and Questions
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My 4 way Active
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Pin 1 XLR probelms
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DC/AC Coupling and Offset...
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The new version will be o...
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  Not all balanced inputs are created equally !
Posted by: David Samborsky - 07-12-2018, 12:56 PM - Forum: Issues and Questions - Replies (2)

Having had the unfortunate experience of dealing with a problematic customer that liked to blame all of his noise issues on the Ultimate-Preamp it turns out that all of the problems can be traced back to a power amplifier with a poorly designed balanced input stage.

Please read about the details in our newly released white paper and how some clever detective work led to the cause without having the offending equipment in front of us.

Not all balanced inputs are created equally


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  Pin 1 XLR probelms
Posted by: MichaelH - 06-11-2018, 02:40 PM - Forum: Issues and Questions - Replies (2)

There has been a lot of discussion about how Pin 1 is implemented on products that have balanced outputs/inputs.

There are numerous ideas, myths and theories floating around as to how this pin grounding should be implemented.

As a consequence in 1995 the AES developed a standard, AES48. The idea of a standards is to make sure that devices made by various manufactures are compatible. e.g. USB, RIAA, etc.

Some nice guy decided to host a website http://pin1problem.com/ which was very good of him.

So I took the liberty to contact some of the worlds best amplifier manufacturers for confirmation that their amps were AES48 compliant.

Their responses will follow.

First out of the gate, Roger Sanders from Sandersmagtech.

Hi Michael,
Thank you for your interest in my products.  To get straight to your question, you can rest assured that the XLR connectors in all my audio components are configured per the AES48 specification.  So there will be no problem using them in your system. 
As an aside, I would like to help you solve your ground loop problem.  Most audiophiles do not thoroughly understand this problem and how to solve it.  It is also good to know that most ground loops are not caused by faulty equipment.  Ground loops can occur with any equipment and in most cases it is not the fault of the equipment.  So let me take this opportunity to explain ground loops in detail and provide practical information on how to correct them. 
Ground loops are formed when you have several components connected to each other -- but each has its own ground formed by the safety ground wire in the mains cord.  If these ground paths are of different lengths, a ground loop will be formed that produces the buzzing sound that is so annoying.
To eliminate the problem, it will be necessary to assure that all the grounds are essentially the same length.  Alternatively, some of the grounds can be disabled so that they cannot contribute to the problem.
So let's look at how to achieve this from a practical standpoint.  In most cases, you will find that the ground loop is formed because some of the components are plugged into different mains outlets.  Outlets are several meters apart and this much distance will cause a large difference in length between the grounding points of the system, which will cause ground loops.
To deal with this, connect all components to the same mains outlet.  This will usually require a multi-outlet strip because you probably have more components than can be accommodated by a single mains outlet.  The multi-outlet strip will act as a single mains outlet and in most cases will eliminate the ground loop.
Once all the electronic sources, amplifiers, preamplifiers, and crossovers are plugged into the same mains outlet, most likely the ground loop will disappear.  If not, then check the lengths of the power cords.  If some are a lot longer than others, that can cause the problem.  Try to use power cords that are close to the same length.
If the problem still persists, then it will be necessary to "lift grounds."  This involves removing the ground from some of the components until the ground loop disappears.
Lifting grounds can be done in several ways.  The most common is to use a "cheater plug" on the end of the power cord.  This is a small adaptor that converts the grounded 3-pin connector on the power cord to a 2-pin connector.  These are commonly available here in the U.S. at any hardware or grocery store for a very cheap price of around $1.  I don't know what is available in other countries, but I suspect there is something similar.
The audio system needs only one safety ground, and that should be your preamp.  So leave its mains cord alone.  Install cheater plugs on all the other components.
The cheater plugs should stop the ground loop.  If so, the next step is to remove one cheater plug from one component at a time until the ground loop returns.  That component is the one most likely to be causing the ground loop. 
In most cases, you will find that lifting the ground on only one component will solve the problem.  If so, you can leave the other power cords alone.  Feel free to experiment with various cheater plug combinations.
Note that some components, especially professional units, will have a switch on them that is specifically designed to lift the ground.  This is because ground loops are extremely common in professional situations.  If the component has a ground switch, you can simply flip the switch instead of using a cheater plug. 
As an aside, I use a special grounding circuit on my amplifiers so that they are virtually immune from causing ground loops.  So they should never require that you lift their grounds.  However, when doing this type of testing you should make no assumptions.  So you can lift the grounds on my amplifiers too just to make sure they are not causing the ground loop.  I just don't expect that you will find that they are the cause.
Using these techniques, you should be able to eliminate the ground loop.  However, some audiophiles object to using cheater plugs.  If so, be aware that there are commercial devices that you can get that will eliminate the ground loop without breaking the grounds. 
There are many such devices available.  A popular one is called Hum-X.  But they all work and can be used to ease concerns about eliminating grounds.
Note that even if the grounds are lifted, audio components are all grounded together by their interconnects.  So as long as at least one component is grounded (usually the preamp), they are all grounded -- even if their power cords are not.  So there is no safety issue caused by lifting grounds as long as at least one component is properly grounded to the mains.
Remember that that ground loops are NOT caused by any fault in the equipment.  All audio equipment is susceptible to ground loops caused by the way the power cords are arranged.  So do not view ground loops as an equipment fault or a quality issue.  They are perfectly normal and can be eliminated by the correct use of the mains.
I suspect that if you deal with the ground loop using the above information that you can get your "unusable" amplifier to work without ground loops.  But if not, then there is another way to make it work.  Simply operate it unbalanced.  Since RCA connectors are not grounded in the same way as XLR connectors, they do not cause ground loops like XLR connectors do. 
I suspect that you want to operate your equipment balanced because you think that produces better performance.  There is a great deal of confusion and misunderstanding among audiophiles about balanced and unbalanced operation.  Most audiophiles feel that balanced operation is better, but they can't tell you why.  So let me take this opportunity to explain how the two systems work and describe their advantages and disadvantages. 
Naturally it seems sensible to prefer a balanced system.  After all, doesn't it seem like a "no-brainer?"  Surely a balanced system would be superior to an unbalanced one.  Who wants something that is unbalanced?
But the truth is that the term "balanced" is a misnomer.  There is actually nothing balanced about a "balanced" system. 
So what exactly is a balanced system and how does it compare to an unbalanced one?  Simply put, a balanced system is where the signal and the chassis grounds are separated.  In an unbalanced system, the two grounds are combined. 
What this means is that a balanced system can have better shielding and therefore can be more effective at rejecting external noise fields than an unbalanced system.  Balanced systems also can reject certain types of internal noise if this noise is in the form of "common mode."
Specifically, RFI (Radio Frequency Interference) and EMI (Electro Magnetic Interference) are external noise problems that often plague professional applications.  Therefore balanced equipment will be required to eliminate the noise. 
For example, when I do live recordings in a concert hall, I have to deal with very large amounts of RFI from the multi-thousand watt light dimmers in a concert hall.  These light dimmers operate on the principle of pulse-width modulation that causes the dimmers to switch the power to the lights on and off very rapidly (typically 120 times per second).   When you switch high power like this, radio frequencies are produced.   This can produce "static" in the recording. 
The microphones have low output and usually will have long cables connected to them.  This makes them very susceptible to RFI.  So to eliminate the RFI problem, balancing transformers are used to convert the unbalanced microphone signal to a balanced one for transmission through the cables to the microphone preamplifiers.  At the microphone preamplifiers, another transformer will be used to convert the signal back to unbalanced for reasons that I will explain in a moment. 
These balancing transformers not only separate the grounds to produce a balanced signal, but they also convert the high impedance of the microphone (typically 50,000 ohms or so) to low impedance (typically 50 ohms).  Low impedance not only increases the ability of the system to eliminate the noise, but it also prevents frequency response errors.   These would occur due to relatively high capacitance produced by long cables from forming an electronic filter that will roll off the frequency response.  So using balanced, low-impedance operation makes it possible to have long cable runs (hundreds of feet) without problems with either noise or frequency response.
There is no free lunch in physics, so you would expect that balanced operation comes with a price.  It does indeed.  That price is that balanced operation is more complex than unbalanced operation and therefore there are more electronics in the signal path.  The additional electronics produce more noise and distortion than you would get from an unbalanced system with similar electronic circuits.  
In the case of the microphone preamplifiers in the above example, we want them to be as quiet as possible.  If we ran the signal balanced through the preamplifier, we would have at least two input transistors or tubes, and more likely, double the entire preamp electronics. 

As a result, the preamp would be twice as noisy as operating it unbalanced. So to eliminate the noise at this critical location in the signal path, it is standard practice to unbalance the signal where it enters the microphone preamplifiers so that there is only one input device used.
Another example of where balanced electronics are necessary is when running long cables from a recording booth to a mixing room.  In this case, there are usually many cable channels running together inside a metal conduit. These cables will have audio signals running through them that can induce electrical currents in their neighboring cables.   This causes crosstalk, where the signals and sound from nearby cables "bleed" into the ones next to them. 
Once again, balanced operation offers superior shielding and this can prevent the crosstalk.  Similar problems are present in most professional applications on stage, so balanced operation has become standard for professional use. 
Yet another advantage of balanced operation is the ruggedness of the connectors.  Professional XLR connectors have locks on them that prevent them from becoming disconnected accidentally.  Can you imagine a performer on stage holding a microphone whose cable was held in place by an RCA connector? It wouldn't take much motion on the part of the performer before the cable would become disconnected.  This won't happen with a locked XLR connector. 
Another advantage of balanced operation is with internally produced hum. If your electronics have a significant amount of hum, this hum will appear on both phases of a balanced system.  In other words, the hum will be "common" to both phases. 
Since the hum signals are out-of-phase with each other in a balanced system, they will cancel each other out, producing a quiet background.   This is known as common mode rejection and does not occur in an unbalanced system because only one phase is used.  So any internal hum will be passed through an unbalanced system while it will be rejected in a balanced one. 
Now let's examine the use of balanced operation in audiophile systems.   To begin, it should be noted that RFI and EMI are almost never a problem in the typical home environment.  So there is rarely any need to operate the system balanced to eliminate external noise. 
Secondly, audiophile equipment usually is very well designed, so there is no audible hum present in it.  Therefore the common mode noise rejection feature of balanced operation will not be needed.  
Thirdly, audiophiles generally do not like transformers in the signal path. So audiophile equipment does not use balancing transformers.  

Instead, the conversions back and forth between balanced and unbalanced operation is done using electronics.  This adds noise, which does not occur if transformers are used.  But both electronics and transformers produce distortion, which degrades the performance slightly compared to unbalanced operation. 
Fourthly, because transformers are not used, the impedance in a balanced audiophile system is not changed to a lower value compared to an unbalanced system.  So the cable lengths in an audiophile system will have approximately the same limits regardless of whether the cables are balanced or unbalanced. 
In short, the advantages of balanced systems will not be needed or used in most audiophile applications.  But balanced operation still causes higher noise and distortion than what you find in the same electronics when run in unbalanced mode. 
Now it must be said that the slight increase in noise and distortion caused by balanced operation cannot be heard by the human ear.  It requires test equipment like a spectrum analyzer to reveal the difference.  But if you don't want to compromise, and you want the most pure sound with the least noise and distortion, unbalanced operation is superior to balanced operation. 
XLR connectors are far more bulky and awkward to use than RCA connectors. While XLR connectors are more rugged than RCA connectors and are required in professional applications, RCA connectors are much more compact, easy to use, and more than adequate in home environments.  
Despite the penalties and limitations of balanced operation, many audiophiles believe that balanced operation sounds best.  How can this be so when it is easily proven that balanced operation has more noise and distortion than unbalanced operation?

The reason is that balanced operation has more gain.  Since two phases are used in balanced operation instead of one as in unbalanced operation, balanced operation plays 6 dB louder than unbalanced operation. 
Understand that when music is louder, it sounds better to us.  Humans can barely hear the loudness difference when music is played 6 dB louder, so most audiophiles will not recognize that when they switch to balanced operation the music is 6 dB louder.  Instead they will recognize that it sounds "better" due to the fact that the music is slightly louder. 
But the truth is that the music actually sounds the same.  If the listener went to the trouble to accurately match levels, he would not hear any difference between balanced and unbalanced operation (even though balanced operation is actually slightly worse). 
The most important point I have saved to last.  That is that the balanced and unbalanced output of a component simply cannot sound different because the signal is the same regardless of its mode of operation. 
Simply put, the signal produced by the component is doubled into two phases in balanced operation, while just one signal is used in unbalanced operation.  But since the two signals are actually the same, they cannot sound anything but identical.
So in summary, from a practical standpoint, it really doesn't matter whether you use balanced or unbalanced operation in most home audio systems.  Both will sound identical to human hearing even though balanced operation has slightly more distortion and noise. 
Personally, I prefer the simplicity and purity of unbalanced operation even though I will freely admit that I cannot hear any difference between the two.  I only use balanced operation when I need to eliminate external noise, such as when doing live recording.
I hope this information has been helpful and that you can finally get your audio system working to your satisfaction.  If you have further questions, please feel free to ask.
Great listening,

Next is Boulder Amplifiers.

Dear Mr. Hope,

All of our current amplifiers adhere to the AES standard (with pin 1 tied to the chassis ground lug) and none of our products have ever placed signal on pin 1.  Assuming that your Preamplifier locates ground (chassis, circuitry, or both), you will have no hum or ground problems.

Best regards, 

Rich Maez
Director, Sales and Marketing
Boulder Amplifiers, Inc.
255 South Taylor Avenue
Louisville, CO  80027
tel: 303-449-8220, x110
mobile: 303-718-9389
web: www.boulderamp.com
facebook: www.facebook.com/BoulderAmplifiersInc

instagram: @boulderamplifiers
twitter: @BoulderAmps


Hello Michael,
Every Parasound model that has XLR connectors is configured for: pin 1 ground, pin 2 positive, pin 3 negative. We have not received reports of compatibility issues with other brands.
Kind regards,
Richard Schram
Parasound Products

From the worlds largest professional audio manufacturer, Harman.

Hi Michael,
The UI24R is wired correctly, as your attached article shows.
Balázs Sólyomi
Back Office Engineer
Professional Solutions, Mixer Group
Szilva utca 1-3.
Pécs, 7632
Phone: +3672509374
Mobile: +36302762788
Email: balazs.solyomi@harman.com
Web: www.harman.com
[Image: ?ui=2&ik=fb2d764046&view=fimg&th=163def0...&zw&atsh=1]

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  DC/AC Coupling and Offset Voltage Issues
Posted by: David Samborsky - 06-05-2018, 05:32 PM - Forum: Wiki, User Guide and Help - No Replies

The following document outlines issues of using DC coupling in the Ultimate Preamplifier with Power Amplifiers and how to reconfigure the outputs for AC coupling.

DC Coupling And Offset Voltage Issues

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  The new version will be orderable when?
Posted by: Accut0n - 05-24-2018, 12:24 AM - Forum: Issues and Questions - Replies (3)

I would really like to order one of the UP versions (Digital / Analogue inputs, balanced outputs). I have been (impatiently) waiting for some considerable time.

Please advise availability probabilities and prices, and shipping to UK. Unassembled or complete.

cheers, Maurice

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  Apple Remote
Posted by: MichaelH - 05-20-2018, 12:58 AM - Forum: Issues and Questions - Replies (1)

Hi all.

If your Apple remote doesn't work it is probably sending out the wrong codes.

You can change this on the remote by doing the following.

With your Ultimate Preamp ON, hold down the MENU and CENTRE buttons for 6 seconds, you will see the "IR RVCD LED" (Bottom LED) on the Preamp flashing when the remote has changed codes.

Try the buttons on the remote. 

If this does not work first time repeat the procedure until the remote works.

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  8 Channel Input via I2S?
Posted by: crawf1982 - 04-23-2018, 07:04 AM - Forum: Issues and Questions - Replies (14)


I have been toying with the idea of getting the Vanity203HD modification board for my Oppo 203 - link

It features an on-board 8 channel I2S header - there is a schematic in the manual

Would it be possible to make a connection between this on-board header and the main UPXO board in order to effectively create an 8 channel preamp/DAC for my home theatre setup?



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  Updated DSP Module
Posted by: David Samborsky - 04-14-2018, 02:33 PM - Forum: The Ultimate Preamplifier Plus (UP+) - Replies (6)

Here is a sneak preview of our updated DSP module (Revision-C) used in the up coming Ultimate-Preamplifier Plus, which replaces the B2 revision board currently being shipped in the Ultimate-Preamplifer. Updates include the all new ES9038PRO Sabre DAC which replaces the existing ES9028PRO Sabre DAC along with a redesigned IV stage to handle the increased current requirements and new regulators to take advantage of the lower noise performance offered by this DAC.

[Image: Ultimate_Processor(Rev-C).png]

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Posted by: MichaelH - 04-12-2018, 02:01 AM - Forum: New users and introductions - No Replies

Hi everyone.

Nice to be on board.

I have had my Ultimate Preamp for 3 months and couldn't be happier. Im looking forward to other users comments.


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  My 4 way Active
Posted by: MichaelH - 04-12-2018, 01:48 AM - Forum: Active Speaker Projects - Replies (4)

This is my own version of the Duntech Sovereign. Doesn't look anything like the Sovereign but based on on Dunlavy's Vertical Symmetrical Array with identical driver spacing to the Sovereign.

Using the Ultimate Preamp in a 6db crossover.

They sound SOOOO SWEET.

Thanks for a superb product Dave. My project wouldn't have been possible without the preamp.

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  New Member
Posted by: MattB - 04-09-2018, 11:23 PM - Forum: New users and introductions - No Replies

Hi all,

Just introducing myself to the new forum, proud owner of Ultimate Pre since last year
Cheers and look fwd to the discussion on the forum


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