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Resources to build in line Attenuator

kleinbje

kleinbje

pfm Member
Hello
Looking to build some attenuator plugs for my Naim 52. I am look to achieve 8-12 db of reduction. I am open to modding an input as well as I believe in less metal in the chain. I had good success with Eichmann silver rca's and Vishay resistors for loading plugs. The KLE input rca jacks, do no look like they would easily mate with the male, unless I built a small box. I am not sure how to calculate the resistor values for hot to hot and hot to ground(0v). Looking for links or advice on best sounding resistors/plugs or other options like a 528 card.Thanks in advance.
 
I determined Zº but now I am not sure to do and Lpad or T pad. Do I match to the streamers 220 rohm or the Naim source 100k. thanks
 
For a start, you want an L pad. You have to choose values at about the middle of the impedance range of output and input.

10k series and 5k1 shunt on the Naim side is about right
 
davidsrsb said:
For a start, you want an L pad. You have to choose values at about the middle of the impedance range of output and input.

10k series and 5k1 shunt on the Naim side is about right
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Thanks so much for replying. Could you explain the impact of the input and output impedance on sound reproduction and why we would not just use the 100k input impedance in our calculations? Given the way current is flowing. I assume there are more than one combination of series and shunt combinations to achieve 10db cut, what guides which combo is best? Is this is something a manufacturer designs on purpose, I would imagine a high input impedance may resist stray voltages and eddy currents, and low output impedance allows for more effective current delivery from the source. Why not have superlow output R and super high input R on all line level components? If we have a fixed voltage 3V, does the output impedance input impedance relationship control how much current flows to the preamp? With a line level music signal how does the amount of current affect sound, given the the max voltage and output impedance are fixed? Thanks, i'm really enjoying learning more about this stuff, had fun making my loading plugs for my SUT.
 
These things are always a compromise, especially for smaller attenuation values.
Too high resistance and stray capacitance at the preamp input roles off the treble and may also cause non linear distortion as capacitance often varies with voltage.
Too low and the source may distort and also give low frequency roll off - a common problem with old Quad tuners. The reason is a series output capacitor.
 
davidsrsb said:
These things are always a compromise, especially for smaller attenuation values.
Too high resistance and stray capacitance at the preamp input roles off the treble and may also cause non linear distortion as capacitance often varies with voltage.
Too low and the source may distort and also give low frequency roll off - a common problem with old Quad tuners. The reason is a series output capacitor.
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Thanks very helpful.
 
Arkless Electronics said:
The OP has such foo fantasy beliefs as to be beyond help.
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Are you saying different connectors and resistors don't sound different? Its my money and for an extra 50$ I actually think parts with tighter tolerances and plugs with more copper in their brass and 100% copper or silver conductors sound better. If you know the physics of what I am doing I would love to hear your thought. Sincerely.
 
kleinbje said:
Are you saying different connectors and resistors don't sound different? Its my money and for an extra 50$ I actually think parts with tighter tolerances and plugs with more copper in their brass and 100% copper or silver conductors sound better. If you know the physics of what I am doing I would love to hear your thought. Sincerely.
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I think you're a troll who's come along to start arguments etc by saying Qanon level stuff, as above, and in every post so far.
 
Arkless Electronics said:
I think you're a troll who's come along to start arguments etc by saying Qanon level stuff, as above, and in every post so far.
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you would be wrong. Where in this post is there anything other than genuine interest and gratefulness? YOU are the one on this thread with nothing productive to say and plenty of insults. I did not realize better understanding L-pads was akin to wearing babies faces. Ok buddy thanks for your contribution, move on.
 
kleinbje said:
you would be wrong. Where in this post is there anything other than genuine interest and gratefulness? YOU are the one on this thread with nothing productive to say and plenty of insults. I did not realize better understanding L-pads was akin to wearing babies faces. Ok buddy thanks for your contribution, move on.
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Your first post that I recall was to ask "EE's and technically knowledgeable people" about sweet spots on a pot. There are non and you were told this by several EE's and a professor but completely ignored it. If you had accepted what genuine experts told you then you wouldn't have started this thread which builds upon your previous one. You've basically given it "ah all the professionals say I'm wrong so I'll ignore them all and continue like THEY are all wrong" Then you say total nonsense about sockets having a sound... You claim "genuine interest" but it's obvious you have your own agenda based on bat shit crazy stuff you've read elsewhere. Unfortunately this is quite common as maybe 85% of everything in the mags, forums and adverts is not just wrong but a pack of lies designed to part the gullible from their money... hence people get fooled into thinking sockets have a sound, often by people who make or sell sockets strangely enough. The worst in fact with this sort of nonsense is those that have been conned into buying such things and will never admit they've been conned so then tell anyone who will listen that it really works...(Emperor's New Clothes) even when it's not possible within the laws of physics. Unfortunately such rubbish spreads by Chinese whispers on forums etc and before you know it we're at "everyone knows special sockets are crucial to good sound so which type should I get?".... WHOA there buckaroo!

FWIW if you really want to waste your time then the 10K and 5K1 suggested up thread will be fine:) Ideally lower output impedance would be nice but you'll end up with either too much attenuation or too low an input impedance at the attenuator input which will/can cause distortion and/or early bass roll off from the source driving the attenuator... so 10K and 5K1 is a good compromise.
You could get round this by using a much higher impedance attenuator followed by an active buffer or by using an active attenuator which attenuates by negative feedback but either adds more active electronics to the signal path....

Yours, a pro EE hi fi designer, ex chief engineer Alchemist Products, ex Musical Fidelity engineer and, FWIW as you're a Naim fan, was headhunted by Naim to be an R & D engineer for them but turned them down;)
 
Arkless Electronics said:
Your first post that I recall was to ask "EE's and technically knowledgeable people" about sweet spots on a pot. There are non and you were told this by several EE's and a professor but completely ignored it. If you had accepted what genuine experts told you then you wouldn't have started this thread which builds upon your previous one. You've basically given it "ah all the professionals say I'm wrong so I'll ignore them all and continue like THEY are all wrong" Then you say total nonsense about sockets having a sound... You claim "genuine interest" but it's obvious you have your own agenda based on bat shit crazy stuff you've read elsewhere. Unfortunately this is quite common as maybe 85% of everything in the mags, forums and adverts is not just wrong but a pack of lies designed to part the gullible from their money... hence people get fooled into thinking sockets have a sound, often by people who make or sell sockets strangely enough. The worst in fact with this sort of nonsense is those that have been conned into buying such things and will never admit they've been conned so then tell anyone who will listen that it really works...(Emperor's New Clothes) even when it's not possible within the laws of physics. Unfortunately such rubbish spreads by Chinese whispers on forums etc and before you know it we're at "everyone knows special sockets are crucial to good sound so which type should I get?".... WHOA there buckaroo!

FWIW if you really want to waste your time then the 10K and 5K1 suggested up thread will be fine:) Ideally lower output impedance would be nice but you'll end up with either too much attenuation or too low an input impedance at the attenuator input which will/can cause distortion and/or early bass roll off from the source driving the attenuator... so 10K and 5K1 is a good compromise.
You could get round this by using a much higher impedance attenuator followed by an active buffer or by using an active attenuator which attenuates by negative feedback but either adds more active electronics to the signal path....

Yours, a pro EE hi fi designer, ex chief engineer Alchemist Products, ex Musical Fidelity engineer and, FWIW as you're a Naim fan, was headhunted by Naim to be an R & D engineer for them but turned them down;)
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I really appreciate your last paragraph. As for the former. Chris West who has been servicing my Naim equipment for the last 12 years or so, very clearly told me that the pot in my 52 had channel imbalance issues below 7-8 o'clock and around 9-10 exhibited the most accurate channel balance. Yes I took his word over some folks on a forum. He has called me the minute he has received a distress email and walked me through solutions, especially with the 82/hicap/250, he has credibility with me. I also ran a unipivot VPI rig, and drove myself crazy adjusting azimuth. I was using a Benz Ruby H which put me at 6-7 o'clock on the dial. When it played real loud 8-10 I seemed to have a better center image, I kept adjusting back and forth, not realizing what was happening. So my past experience also informed my decision to try to build an Lpad. As for the title, I just didn't want people to tell me to get a Dave;) I have no interest in putting others down, I just thought it would be a fun and cheap project to try, as I was now hearing the detrimental effects of the digital volume control in the Cary. I've been in the ER for the last 2 years straight with this craziness, its a great distraction. I have never listened to wbt's vs kle etc, so no comment there. I have very distinctly heard differences that are describable between signal, power, and digital cables, as well as power supplies. I alway return to the original setup to reevaluate by subtraction. I have been initially fooled in the past, stillpoints feet on my old VPI table, no good on reeval. HRS record weight, way too much damping of the sound. Hated the Chord Anthem 2 din/xlr immediately between 82/250 way to sharp highs. I ultimately judge every change to my system by how often I'm singing, getting goosebumps, or being forced to look up and listen. The ultimate measure being how long the urge to continually play old favorites to hear how they sound, NOW.

What about coupling a resistor to the output or input to reduce the current delivery without using digital attenuation? I believe the 52 has daughter boards for each input, is their a mod to be had there? I picked up a cheap pair of 10db attenuators off amazon to experiment. It killed the cymbals, but I can hear some promise. I'll grab the 5/10 combo and give it a go. I had a Lamm LP2 and I assumed the internal Jensen SUT's with no extra plugs;) cabling, let alone two signal breaking connections. I still very much preferred the Ear MC4 and then Ypsilon SUT into the MM stage. I also found upgrading to WE417's and a Mullard rectifier improved my listening experience in a big way.
"Ideally lower output impedance would be nice but you'll end up with either too much attenuation or too low an input impedance at the attenuator input which will/can cause distortion and/or early bass roll off from the source driving the attenuator."
Could you expand on that, I've very interested in the physics of whats happening to the electrical signal to cause that? I would think with a fixed V(3) R(Attenuator and 100k input impedance)) then the current would increase if you lowered the output impedance.
BTW I'm far from a troll, see my post on system pics 2022, or my 20 years of posts on the steve hoffman forum. Looking forward to your explanation to the bolded..

Regards
Jeff
 
I'll keep this brief... and you ain't going to like it...

First of all power cables and digital cables cannot have any effect. Simply impossible so anything you and all the others who reckon they sound different think you hear is down to the imagination. Also rectifiers don't effect sound.

There is no difference between a cheap attenuator and an expensive one. It's simply 2 resistors.

There can be and often is a channel imbalance at the bottom end of a pots rotation but with good quality pots there should be no noticeable channel imbalance at "normal" listening levels. Fit a switched attenuator if you want to be sure as they have perfect channel balance. Your other thread suggested that you think the actual sound quality has a sweet spot!.

Forget current in this context. Generally speaking an amplifier "measures" the input signal... it is not "driven" by it.

There are many on line tutorials about these sort of things and a great book on electronics is "The Art of Electronics" by Horowitz and Hill.
 
Arkless Electronics said:
I'll keep this brief... and you ain't going to like it...

First of all power cables and digital cables cannot have any effect. Simply impossible so anything you and all the others who reckon they sound different think you hear is down to the imagination. Also rectifiers don't effect sound.

There is no difference between a cheap attenuator and an expensive one. It's simply 2 resistors.

There can be and often is a channel imbalance at the bottom end of a pots rotation but with good quality pots there should be no noticeable channel imbalance at "normal" listening levels. Fit a switched attenuator if you want to be sure as they have perfect channel balance. Your other thread suggested that you think the actual sound quality has a sweet spot!.

Forget current in this context. Generally speaking an amplifier "measures" the input signal... it is not "driven" by it.

There are many on line tutorials about these sort of things and a great book on electronics is "The Art of Electronics" by Horowitz and Hill.
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Thanks for the explanations, appreciate your time. I'll definitely check out that book, if you know of a particularly good tutorial do let me know.
My system has a lot of gain and the pot on the preamp goes from 6:30 to 5:00 roughly. I was listening comfortably at 7-8 max with the Ruby H. Sound was clean and clear but I didn't realize the pot could cause those balance issues. Now its 70 db at the chair at 8:00-8:30 vinyl, digital 7:00. I don't want to debate the merits of cables, but when it's safe and you're in my neck of the woods, you can listen for yourself(with dram of course), while I swap cables. Cheers. Jeff
 
So I'm talking to one of the techs at Parts Connection. He is leading me towards 100k both shunt and series. He told me matching the input impedance to the shunt resistor and the series at 100k would give 9.5 db in attenuation. Not doubting the recommended values, just want to understand the 2 schools of thought.
 
kleinbje said:
So I'm talking to one of the techs at Parts Connection. He is leading me towards 100k both shunt and series. He told me matching the input impedance to the shunt resistor and the series at 100k would give 9.5 db in attenuation. Not doubting the recommended values, just want to understand the 2 schools of thought.
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That is for when you want the attenuator to change the sound. Some treble roll off and bonus harmonic distortion, with extra hiss and maybe hum from the amplifier seeing a high source impedance
 
davidsrsb said:
That is for when you want the attenuator to change the sound. Some treble roll off and bonus harmonic distortion, with extra hiss and maybe hum from the amplifier seeing a high source impedance
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Whilst I agree with you on the results that would be obtained it's bollox advice from someone who hasn't a clue not "for when you want the attenuator to change the sound"....
 
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