[davidrs]

What are the benefits and weaknesses of using Stepped Attenuators?

These are the type made by Electronic Visionary Systems / Ric Schultz or by Endler Audio, etc. that are used to replace an active linestage / preamp.

Application I am considering would be from the analog outputs of a BDP to a set of 5 attenuators plugged into a 5 channel amp (primarily for ht purposes).

Thanks.

[*Scotty*]

Stepped attenuators are fine. What you are talking about is using just an attenuator between your source and power amp with no way to actively match the impedance between the devices. Some people like the sound of a passive preamp because it can be very clear sounding when compared an inferior active preamp. The down side is that the clarity usually comes at the expense of bass extension and dynamic attack across the entire frequency range. The music will also tend to sound harmonically thin and lacking in body or weight.
Scotty

[Steve]

What are the benefits and weaknesses of using Stepped Attenuators?

These are the type made by Electronic Visionary Systems / Ric Schultz or by Endler Audio, etc. that are used to replace an active linestage / preamp.

Thanks.

As general information, it does not replace an active linestage/preamplifier since the preamplifier gainstage is simply installed in the amplifier to obtain the necessary db gain, now called an integrated amplifier. The active preamplifier is simply added to a basic amplifier. This is backed up multiple times by Stereophile's definition of an "integrated amplifier". There are pluses and minuses to each type of design.

I hope this helps in understanding the difference between a basic amplifier and integrated amplifier.

Cheers.

[srb]

As general information, it does not replace an active linestage/preamplifier since the preamplifier gainstage is simply installed in the amplifier to obtain the necessary db gain, now called an integrated amplifier. The active preamplifier is simply added to a basic amplifier. This is backed up multiple times by Stereophile's definition of an "integrated amplifier". There are pluses and minuses to each type of design.

I hope this helps in understanding the difference between a basic amplifier and integrated amplifier.

I don't think David is asking about the difference between a power amplifier and an integrated amplifier.  From his description, he is asking about taking the output from a Blu-ray player into a passive stepped attenuator and then into a power amplifier that has no additional preamplifier gain.
 
My answer would be (unfortunately) it depends on the impedance match between the disc player and the amplifier, as well as the power amplifier gain.  Some have found it to work very well, while others have found a lack in dynamics and body.
 
Perhaps if you listed your disc player and power amplifier, someone who has tried this setup with the same or similar power amplifier could comment.  I would think that most who have tried it, did so with a 2-channel stereo setup, but if your 5 channel amplifier has a two channel equivalent model, it may be relevant.
 
Steve

[Bill Baker]

As others have mentioned, stepped attenuators (or passive attenuators in general) may or may not be the best solution depending on your amplifier.

 Another aspect to consider with "stepped" attenuators is that you don't have much control over the lower listening levels. Finding the proper resistance as well as the design of the attenuator can be critical if you need finer adjustments at lower listening levels.

 You may have to simply try one and see how it works in your setup. It sounds like your amp is solid state so you will want to look at 10K-20K ohm attenuators.

 As Scotty mentioned, the biggest downfall I find is the loss of weight in the presentation. Especially with solid state. To me it has always seemed like something was "missing". Especially in the midrange.

 Like anything audio YMMV.

[davidrs]

Steve (SRB) is correct.

"From his description, he [David] is asking about taking the output from a Blu-ray player into a passive stepped attenuator and then into a power amplifier that has no additional preamplifier gain."

Assume that the impedances and gain are within tolerances. I.E. assume it is doable.

I am trying to get a feel for whether folks who have tried this approach have had success and been satisfied with the results.

The BDP is an OPPO 83SE.  I do not have the multi-channel amp as yet, but if I were to go forward with this type of setup, the BDP and amp would obviously need to be compatible to allow for this particular application.

I also realize most who have done so, have done so with 2 channels.

*Scotty* - Thanks for your comments.

Steve - Hope SRB's response cleared up what I was asking. Any thoughts, given that?

Best,

David.

[Bill Baker]

Hi David,
 The simple answer is "Yes" it will work. As I mentioned in my response above, there are some characteristics which only you will be able to decide are acceptable.

[davidrs]

Hi David,
 The simple answer is "Yes" it will work. As I mentioned in my response above, there are some characteristics which only you will be able to decide are acceptable.

Your RESPONSE  came through as I was typing the last post.

Really appreciate your feedback. Good to know the limitations that you mention. They are points that would keep me from going this route.

Both manufacturers I listed do provide the pros and cons and are upfront about the limitations and the need for a 'fit' between the source - attenuator - amp.

[Steve]

Steve - Hope SRB's response cleared up what I was asking. Any thoughts, given that?

Best,

David.

Hi David. I was just providing general information to the public/newbies that a passive stepped volume control does not replace an active preamplifier because the active preamp gain is in the integrated amp by definition.

However, depending upon the implimentation of the stepped control, IC capacitance may have to be included in the equation vs having the volume control inside the amplifier. The IC capacitance may have a detrimental effect on high frequency response, thus I would recommend an IC with minimal capacitance. I hope this clears up any confusion. 

Cheers.

[davidrs]

However, depending upon the implimentation of the stepped control, IC capacitance may have to be included in the equation vs having the volume control inside the amplifier. The IC capacitance may have a detrimental effect on high frequency response, thus I would recommend an IC with minimal capacitance. I hope this clears up any confusion. 

Cheers.

Steve,

Helps tremendously. Will add that to my list of things to check-up on, to make sure this is feasible.

Still not sure which way I am going to go. I can always test it out within a 2ch context before going with all 5 channels. The approach is intriguing and I am willing to give it a try if there is some positive feedback, if only for the learning that will come with it.

I have experience with a transformer volume control and was able to get a feel for it limitations, as well as what it did well. The passive attenuator approach would allow me to experience a more esoteric application.

Appreciate your comments.

- David.

[Steve]

Steve,

Helps tremendously. Will add that to my list of things to check-up on, to make sure this is feasible.

Still not sure which way I am going to go. I can always test it out within a 2ch context before going with all 5 channels. The approach is intriguing and I am willing to give it a try if there is some positive feedback, if only for the learning that will come with it.

I have experience with a transformer volume control and was able to get a feel for it limitations, as well as what it did well. The passive attenuator approach would allow me to experience a more esoteric application.

Appreciate your comments.

- David.

Thanks David. Is the output of the source dc coupled or capacitive coupled? DC coupled gives the passive the low frequency edge.

As far as the highs, will depend upon the IC capacitance, total  resistance/volume setting of passive vs leakage inductance/distributed capacitance, IC capacitance etc of the transformer. Could have ringing concerns with transformer depending upon transformer tap. I believe Steve N mentioned lack of volume steps etc as well.

Cheers. 

[davidrs]

Steve,

Just got an email off to Oppo with the specific question ("Is the output of the source dc coupled or capacitive coupled?") you posed, as well as some others.

They do not have this level of information detail available in their 'detailed' specs. And I do not have the level of knowledge to know which one it might be.

Thanks for your assistance.

- David.

[davidrs]

"Is the output of the source dc coupled or capacitive coupled? DC coupled gives the passive the low frequency edge."


Steve,

Here is the response from Oppo:


"1. The stereo output is DC coupled.  The 7.1ch output is capacitive coupled."

"2. The player has been designed to work with receiving equipment which is expecting an input impedance between 10K and 40K. As long as the input impedance on the amplifier is 1K of higher, they should be compatible."

Unfortunately, the analog multi-out is capacitive coupled.

Additional thoughts?

- David.

[Steve]

"Is the output of the source dc coupled or capacitive coupled? DC coupled gives the passive the low frequency edge."


Steve,

Here is the response from Oppo:


"1. The stereo output is DC coupled.  The 7.1ch output is capacitive coupled."

"2. The player has been designed to work with receiving equipment which is expecting an input impedance between 10K and 40K. As long as the input impedance on the amplifier is 1K of higher, they should be compatible."

Unfortunately, the analog multi-out is capacitive coupled.

Additional thoughts?

- David.

Hi David,

I think with capacitive coupling output I would go with the resistive passive control. Maybe others found different?

Cheers.

[gstew]

I'm a long-time passive user and have used several variations of high-test stepped attenuators and also various pots. What I don't have is experience with transformer-based controls, so take these comments in that light.

Benefits are great transparency & detailing for the $ IF THEY ARE DONE RIGHT. Weaknesses are they don't work with many combinations of equipment and have to be situated at the amplifier input for the best results.

Several things...

1. How well a passive will work is dependent on several factors, but the most basic and key one is having a low-ish output impedence(1k or lower, much lower is better) from your upstream component and a high-ish input impedence (20k or higher, 50k-100k better) into your downstream component. If you don't have this, don't bother.

2. Having a short connection between the output of your passive and the input of your downstream component is important for both treble extension and perceived dynamics. Both EVS and Endler Audio have units that mount on the input of your amplifier and this is best by far. If your setup requires you to have a meter or even 1/2 meter of IC between the control unit and the output of the resistive attenuator, again, don't bother.

3. Component quality is key with these types of attenuators. If doing a stepped attenuator, don't expect garden-variety carbon composite resistors to sound as good as metal films, don't expect garden-variety metal-films to sound as good as Holco or PRP, don't expect these to sound as good as Vishay or a good Tantalum. Switch quality will also matter and I've had my best experiences with the exotic Shalco or Daven multi-position silver-contact switches, but these are very expensive, I've also heard good things about the Seiden switches available through places like DIYHiFiSupply.com. I am sure the resistors and Elma switches that EVS and Endler Audio use are good-sounding and the switches durable, but I haven't used either of theirs. If you're doing a resistive potentiometer-type, again, part quality again is important, but what listening I've done with them indicated that the mid-dollar ones may vary a lot in sound quality. IMHO, I wouldn't expect to do a good-sounding stepped attenuator for anything less than Endler Audio's at about $140 a pair. At the upper end the Shalco/Daven/Seiden switches are roughly $300-$400 for just the switches alone!

4. Configuration also matters a lot. In the stepped attenuator world, the shunt-type pioneered by EVS and also used by Endler is best, with ladder next and series last. In the resistive potentiometer-type, a linear pot with a law-faking resistor is best followed by a log-pot, given pot-quality as equal.

In a setup where the components are compatible to this solution where it is done well, you have to spend a LOT more $ in a preamp to approach the transparency and purity of a good resistive passive... and in my experience, with no loss of dynamics and bass power. Done wrong, you'll wish for an active preamp.

Greg in Mississippi

P.S. On the Oppo's output capacitors, see the Oppo comparison on the EVS site. He shows how to bypass the output capacitors on the Oppos for a direct-coupled output.

P.P.S. There's a good discussion of switches for volume controls in the original monster Blowtorch thread on DIYAudio.com.

[davidrs]

Greg (gstew):

Very informative and helpful. Thanks!

Good to know the output capacitors on the Oppo can be bypassed. I may go with their BDP93 when it comes out, and if so, will need to wait until I get my hands on one.

Will check out the DIYAudio thread as well.

- David.

 

[Lonerangerll]

I broke the attenuator knob off on my ADS C1500 control amp for the  ADS PB1500 Subwoofer vin. 1980. It is a stepped attenuator which controls volumn for two internal 100watt amps and the passive line which attenuates the main amp for the satelites. Anybody have any idea what to replace it with? There was a post I read a few weeks ago where a guy replaced the same with an alps but i cannot find the post. Iam new to audio Circle and dont know the ropes yet on contacting members. I did recieve an inquiry from some one else on the above ADS components.

[Rclark]

it's not true about length of ic. I've got a 1/2 meter of ic with my ldr and it works fantastically. Treble, bass, everything utterly fantastic. Also extremely good at low level control. Of course, this is not merely a stepped attenuator, but a much nicer battery powered passive.

[Æ]

I broke the attenuator knob off on my ADS C1500 control amp for the  ADS PB1500 Subwoofer vin. 1980. It is a stepped attenuator which controls volumn for two internal 100watt amps and the passive line which attenuates the main amp for the satelites. Anybody have any idea what to replace it with? There was a post I read a few weeks ago where a guy replaced the same with an alps but i cannot find the post. Iam new to audio Circle and dont know the ropes yet on contacting members. I did recieve an inquiry from some one else on the above ADS components.

Your best bet would be to replace it with something identical. You can replace a stepped attenuator with a potentiometer of the same value. You have to be able to solder and know how to use an ohmmeter. A schematic, parts list and or wiring diagram would be very helpful to have.

[*Scotty*]

Rclark, your LDR is an active impedance matching device and is not passive, it does have one characteristic in common with a true passive attenuator, it has no gain.
 The LDR will have a limitation on how much cable it will drive but it is still much better off than a true passive which has no impedance matching capability, 1/2 meter IC is nothing to an LDR, 30ft. with a lot of capacitance per foot might be a problem.
 The passive attenuator has one advantage over the LDR, it does not add distortion, it does not have a "transfer function" or non-linearity because it is not a semi-conductor device.
Scotty