Paul, I bought one of your and Stan Warren's phono preamps by mail and then a line stage when you introduced it! My ARC (SP3) friends thought I was nuts! Later I bought one of Stan's Superphon preamps and still have it to this day.. I've been on a long journey with you guys! My best...
That's exactly what my preamp is "No Preamp". I've built myself a beautiful stepped attenuator and a 6-way double pole selector switch in an all aluminum box (very short wiring). That allows selection of my audio sources, via attenuation to feed directly into my KT88 equipped VTA ST-120 amplifier. Sounds simply wonderful. ❤
The voltage sent from a source to the amplifiers needs to be controlled. There are 3 types of line level/ volume controls most often used. Starting with the worst approach, digital volume controls direct from a DAC into the amps. If you happen to have a perfect match, say a 2V peak output from the DAC with a 2V sensitivity to full output in the amp. a direct connection will drive your system to full volume all the time. To cut the volume in half you have to remove the most significant bit/ cut the sample bit depth in half. You want a 1/4 volume? Take that 16 bits and covert it to 4 bit depth. Peak voltage out will be what you want for volume but all resolution is gone! So instead of bit removal to get reduce voltage out, some adopt a VCA, Voltage Controlled Amplifier stage. They control the amount of voltage fed to the output stage so it can only vary between zero and that reduce voltage. So the entire 16, 24, 32 bits will always be resolved. Problem is an amp's sound will change based on it's supply voltage. So the sound will change quite a bit as the volume is adjusted. The best is the old fashion passive volume control. Be it a POT/ variable resistor or a resistor ladder. The full output voltage from the source is applied to one side and the amount voltage out depends strictly on were the output is tapped off of that resistor. Want a 1/4 volume, use 1/4 of the way across the resistor section. The entire 16. 24, 32... bits will always be resolved. Only the voltage level to the amp changes. Well except in the real world there are always other outside components. Primarily capacitors at the output of the DAC and input to the amps. The passive volume control acts as a R/C circuit then. R/C circuit are used for high or low pass filtering. The added resistance can cause high end roll off. So they build active circuits around it.
Majority of modern ‘audiophile’ passive pre’s do not employ series resistor pots. Most are using autoformers, multi-tap transformers, as a volume control with lower output impedance. This can be very effective with most modern DAC’s, some of which too have buffered volume controls in output section and enough output voltage to easily drive the amps.
Passive is not for every situation. An excellent alternative is a high quality autoformer. Dave Slagle makes an AVC that is pretty sweet. The output Z drops as attenuation increases starting at 100 ohms and dropping to nothing. My source has a nice tube output, so the AVC is quite a good match. It is basically a wire up to around 250kHz. I found any type of resistance pot noticeably inferior for my taste.
Paul is correct. The other issue is that any kind of resistor will have some amount of inherent noise. The higher the resistor value, the higher the noise. A 100K pot at room temp will have an effective noise of about 5uv. A 10K pot will have its noise around 1.7uv. If your amp has sufficient gain, you will definitely hear the difference.
@tristanjones7735,so a single resistor is an issue but an active pre-amp with loads of resistors,transistors/tubes and capacitors in the signal path is`nt ?
I settled on an Ypsilon transformer "passive pre-amp". I find it by far the best pre-amp l have heard, certanly better than a high quality resistor ladder unit l had for awhile. Great dynamics and transparency. It requires system matching though as it doesn't provide gain of course.
First of all, a passive pre-amp does not exist. Nothing gets amplified. If you want to do a passive volume control, do it with an attenuation transformer. This also has the advantage to lower the impedance as you step down the output signal. Further more, a passive volume control is best used with a tube amp that has a very high input impedance. Ideally the power tube amp has full output at line level input (200 mV). Many tube amps can do this with only two stages witch results in a very direct signal path. At this point, the set up is basically a full amplifier with out board volume control. There is nothing wrong with that.
I just built a passive volume control with a GOLD POINT 47 step 10K attenuator. No issues driving a pair of DIY Hypex Nilai 500 monoblocks with a 48K input impedence. Clarity is superb. I'm considering swapping in a 5K GOLD POINT to see if the old 10:1 impedence rule makes a difference. Right now, 5:1 seems to be working well.
A passive attenuator will be superior to any active pre-amp if the following is observed;very low cable capacitance to and from the attenuator;source equipment with low output impedance and high input impedance of amp or in my case active crossover being driven. The usual problem of lack of dynamics is when incompatible equipment is used;ie.low input impedance amps which results in lack of current drive.
Paul - not sure if I’m the first here to say that as one of your septuagenarian viewers, I can fondly remember owning one of those dual chassis phono pre/line stage combos and the first brick power amp as part of my constantly shifting arsenal of audio weaponry “back in the day”. However, I’d be lying if I stayed I can remember the differences I might have heard between the passive and active mode on the line stage - far too many changes of gear, and too many magic cigarettes during those couple of decades before parenthood. What I can remember is that Acoustat II, dual mono bridged Model II amps and Polk “Cobra” cable was not a particularly stable or synergetic combo - a different kind of magic smoke there😂 Cheers
Different than passive preamp as you described is the transformer volume control . It does some things better , but a very high-end unit can cost as much as a preamp with gain & more drive .
Paul, Just received your Octave Records email. Really enjoyed the 1950s Jazz re-recordings. Listening to Take 5 got my feet tapping! Oh, before I forget. Your listed as alto sax player? I must have missed something along the line because I was clueless to the fact you play sax. I sampled all of the recordings, great job!
"Passive" pre-amps are NOT isolated from the output caps feeding the "pre-amp" and any input caps at the receiving end. So essentially what you got is some type of R/C (or R/C2) filter since the "pre-amp" is coupled (not isolated) from the input device and the device it's feeding. Unless both connected devices have purely resistive impedance you will most definitely alter the frequency response curve of the input.
Passive pre-amplifier is an oxymoron? Passive volume control or stepped attenuator more like. Switched resistor pairs are much better than a pot due to pretty much anything, better tolerance, control of the input and output impedance, switch quality, etc. Pots are just lazy, the impedance is what it is, mechanical issues, deviation from ideal Log etc. I still have a passive stepped attenuator switched in 6dB steps, based on much less than 6 dB isn’t worth getting out the chair for. :- ) Very short (6”) captive cables designed to just reach from my pre to the power amp. Note; Cables _do_ matter with passive controls. (capacitance)
"Passive pre-amplifier is an oxymoron?" - While i totally get your point, you could argue 'passive pre-amplifier' as a passive device that signal goes through before (pre) the amplifier. Semantic jiggery-pokery I know... you can tweak language far too much really, it's no wonder we humans get so confused with each other all the time. And yes, that definition would also include interconnects - we work with what we got eh:D
Yeah excellent comment about the switching resistors. I found a box on ebay which is just relay based volume control it looks good- around 100 bucks. The knob on the front runs the relay. I wonder if it’s any good long term. This has to be the best way to get rid of the impedance problem. As you said as long as the cables can be kept short this method should be superior to an active gain stage. I think for some people dealing with passive solutions might be too inconvenient for them. Also having a preamp that is truly transparent sounding is very expensive.
There are some really high inpedance power amps that certainly give you better matching. A friend had a reputable brand pre amp (old 'sqcool' british)and in that case a passive trumped it completely - though the device was getting a bit old I must say....
Even if you have a high impedance power amp, there is still the issue of the capacitance of your interconnects effectively forming a rc filter, attenuating the top end.
@@paulstubbs7678 Never noticed more top when I went active, and the opposite with the old sqhool replacement, though I have always kept cables as short as possible...
Hello. I have an amplifier. Naim NAP250 clone card and have made my own amplifier. When I use different active preamplifiers, the sound is always worse, especially in treble details. I have tried one that only has op amp ic. and no coupling capacitor and a slightly more advanced one with a coupling capacitor on the output. I find my passive preamplifier to give better sound and more transparent sound. The passive only has an input selector and potentiometer which is connected to my DAC. which is connected to my computer. I have done the test many times with the same result. I don't know why I'm experiencing this. Naim has a coupling capacitor on the input
It’s interesting if such “passive pre-amp” alters the sound at an audible level. If all it contains are switches and purely resistive components, what comes out is a ratio of what comes in (
Passive means changing the impedance of i/p and o/p sources, and setting up series/parallel impedances, not good in my opinion. A fixed matching input (47k) converted into a less than 75ohm output Z with individual resistor(s) for volume is a likely better setup.
Is a passive pre amp really a "pre amp"? It's not "amping" anything and is really only turning down the gain coming from other equipment. Which I can't understand being I have never had equipment that I need to do so and for that matter had to turn most things up.
"Grinding away", power tools, on a carpeted floor and a white couch - Boy are you keen, obviously your wife is many miles away. (I wouldn't last 10 seconds doing that here)
I use a Shiit Audio Freya + with my McIntosh MC275. That preamp gives you the option to run it as a passive preamp, I never use it, sounds lifeless to me.
Start at 0.5W as first step, not loud enough, and then 1W, 2W, 4W, 8W, 16W, (into good area now) 32W, 64W (Party time) 128W. I make that 9 steps, mine has 8. Honestly, I really don’t think it’s a problem, 3dB if you wish, but that’s a perceptible change, and as I said, I can’t be arsed with getting up for such a small change. The attenuator was more of a development step, the real issue was control of input and output impedance, and the cable capacitance combining to form a low-pass filter, knowing phase starts to move a decade below attenuation. (3dB bandwidth at 20KHz has a phase shift starting at 2KHz)
Has anyone thought about stereo width? The more resistance you have between signal L R The less stereo you get. a potentiometer always gives a certain resistance across L and GND and R and GND. since both GNDs are connected, you get a load over L R that varies up and down. you get more and less stereo when you turn the volume up and down. at low volume you get less stereo If this is wrong, please let me know.
The opposite of a passive preamp is when they discovered that way oversized power supplies added to preamps improved sound quality in many ways.
Paul, I bought one of your and Stan Warren's phono preamps by mail and then a line stage when you introduced it! My ARC (SP3) friends thought I was nuts! Later I bought one of Stan's Superphon preamps and still have it to this day.. I've been on a long journey with you guys! My best...
The 10K pot , is an excellent trick. Very good
That's exactly what my preamp is "No Preamp". I've built myself a beautiful stepped attenuator and a 6-way double pole selector switch in an all aluminum box (very short wiring). That allows selection of my audio sources, via attenuation to feed directly into my KT88 equipped VTA ST-120 amplifier. Sounds simply wonderful. ❤
The voltage sent from a source to the amplifiers needs to be controlled. There are 3 types of line level/ volume controls most often used. Starting with the worst approach, digital volume controls direct from a DAC into the amps. If you happen to have a perfect match, say a 2V peak output from the DAC with a 2V sensitivity to full output in the amp. a direct connection will drive your system to full volume all the time. To cut the volume in half you have to remove the most significant bit/ cut the sample bit depth in half. You want a 1/4 volume? Take that 16 bits and covert it to 4 bit depth. Peak voltage out will be what you want for volume but all resolution is gone!
So instead of bit removal to get reduce voltage out, some adopt a VCA, Voltage Controlled Amplifier stage. They control the amount of voltage fed to the output stage so it can only vary between zero and that reduce voltage. So the entire 16, 24, 32 bits will always be resolved. Problem is an amp's sound will change based on it's supply voltage. So the sound will change quite a bit as the volume is adjusted.
The best is the old fashion passive volume control. Be it a POT/ variable resistor or a resistor ladder. The full output voltage from the source is applied to one side and the amount voltage out depends strictly on were the output is tapped off of that resistor. Want a 1/4 volume, use 1/4 of the way across the resistor section. The entire 16. 24, 32... bits will always be resolved. Only the voltage level to the amp changes. Well except in the real world there are always other outside components. Primarily capacitors at the output of the DAC and input to the amps. The passive volume control acts as a R/C circuit then. R/C circuit are used for high or low pass filtering. The added resistance can cause high end roll off. So they build active circuits around it.
Boy stop telling the truth in public.wow.. you sound old and smart..haha..and your correct in my opinion..
@@davidstevens7809 Old, ya! And been around, ya. and can sound smart at times, ya. Able to control responding, Not so much.
Passive control unit would be a better description, seen as it isn't actually an amplifier.
Dare to call it an oxymoron and you'll get intimidated. Welcome to Fentanyl.
That seems to be an industry wide convention of calling these passive pre-amps. Crazy stupid term but that’s what is used.
Majority of modern ‘audiophile’ passive pre’s do not employ series resistor pots. Most are using autoformers, multi-tap transformers, as a volume control with lower output impedance. This can be very effective with most modern DAC’s, some of which too have buffered volume controls in output section and enough output voltage to easily drive the amps.
Passive is not for every situation. An excellent alternative is a high quality autoformer. Dave Slagle makes an AVC that is pretty sweet. The output Z drops as attenuation increases starting at 100 ohms and dropping to nothing. My source has a nice tube output, so the AVC is quite a good match. It is basically a wire up to around 250kHz. I found any type of resistance pot noticeably inferior for my taste.
Same here!
I just explained to my brother that serious relationships are about compromise and respect! Who'd have thought audio engineering is like marriage!
I owned a Mod Squad Line Drive Deluxe 30+ years ago and it ranks in the top 5 audio components that I wish I'd never sold.
Paul is correct. The other issue is that any kind of resistor will have some amount of inherent noise. The higher the resistor value, the higher the noise. A 100K pot at room temp will have an effective noise of about 5uv. A 10K pot will have its noise around 1.7uv. If your amp has sufficient gain, you will definitely hear the difference.
@tristanjones7735,so a single resistor is an issue but an active pre-amp with loads of resistors,transistors/tubes and capacitors in the signal path is`nt ?
@@BRATWURST1 Sure, an active preamp can add a TON of noise if not designed correctly. However the question is why do people like passive preamps.
I settled on an Ypsilon transformer "passive pre-amp". I find it by far the best pre-amp l have heard, certanly better than a high quality resistor ladder unit l had for awhile. Great dynamics and transparency. It requires system matching though as it doesn't provide gain of course.
First of all, a passive pre-amp does not exist. Nothing gets amplified. If you want to do a passive volume control, do it with an attenuation transformer. This also has the advantage to lower the impedance as you step down the output signal. Further more, a passive volume control is best used with a tube amp that has a very high input impedance. Ideally the power tube amp has full output at line level input (200 mV). Many tube amps can do this with only two stages witch results in a very direct signal path. At this point, the set up is basically a full amplifier with out board volume control. There is nothing wrong with that.
My pre amp is a 47 step attenuator built by GOLD POINT in Calif. and I like that the signal is clean end to end
I just built a passive volume control with a GOLD POINT 47 step 10K attenuator. No issues driving a pair of DIY Hypex Nilai 500 monoblocks with a 48K input impedence. Clarity is superb. I'm considering swapping in a 5K GOLD POINT to see if the old 10:1 impedence rule makes a difference. Right now, 5:1 seems to be working well.
@@ericlarsen1721 I had them build it. 4 RCA out 1 in couldn't be happier a little pricey but worth it
What Edison actually thought but did not say. The easiest way to invention is to use someone else's hard work, be it bought or stolen.
Beat me to it
A passive attenuator will be superior to any active pre-amp if the following is observed;very low cable capacitance to and from the attenuator;source equipment with low output impedance and high input impedance of amp or in my case active crossover being driven.
The usual problem of lack of dynamics is when incompatible equipment is used;ie.low input impedance amps
which results in lack of current drive.
Paul - not sure if I’m the first here to say that as one of your septuagenarian viewers, I can fondly remember owning one of those dual chassis phono pre/line stage combos and the first brick power amp as part of my constantly shifting arsenal of audio weaponry “back in the day”. However, I’d be lying if I stayed I can remember the differences I might have heard between the passive and active mode on the line stage - far too many changes of gear, and too many magic cigarettes during those couple of decades before parenthood.
What I can remember is that Acoustat II, dual mono bridged Model II amps and Polk “Cobra” cable was not a particularly stable or synergetic combo - a different kind of magic smoke there😂
Cheers
Different than passive preamp as you described is the transformer volume control . It does some things better , but a very high-end unit can cost as much as a preamp with gain & more drive .
Paul,
Just received your Octave Records email. Really enjoyed the 1950s Jazz re-recordings. Listening to Take 5 got my feet tapping! Oh, before I forget. Your listed as alto sax player? I must have missed something along the line because I was clueless to the fact you play sax. I sampled all of the recordings, great job!
a passive pre is not a pre. its an input selector switch
I love my Goldpoint XLR passive preamp🥴
I think he is in his workplace, sofa corner
I farted Paul
May I suggest Gas-X.
"Passive" pre-amps are NOT isolated from the output caps feeding the "pre-amp" and any input caps at the receiving end.
So essentially what you got is some type of R/C (or R/C2) filter since the "pre-amp" is coupled (not isolated) from the input device and the
device it's feeding. Unless both connected devices have purely resistive impedance you will most definitely alter the frequency response curve of the input.
Schiit has the SYS and I've been wondering about it to switch between my DAC and other sound source.
Passive pre-amplifier is an oxymoron? Passive volume control or stepped attenuator more like. Switched resistor pairs are much better than a pot due to pretty much anything, better tolerance, control of the input and output impedance, switch quality, etc. Pots are just lazy, the impedance is what it is, mechanical issues, deviation from ideal Log etc. I still have a passive stepped attenuator switched in 6dB steps, based on much less than 6 dB isn’t worth getting out the chair for. :- ) Very short (6”) captive cables designed to just reach from my pre to the power amp. Note; Cables _do_ matter with passive controls. (capacitance)
"Passive pre-amplifier is an oxymoron?" - While i totally get your point, you could argue 'passive pre-amplifier' as a passive device that signal goes through before (pre) the amplifier. Semantic jiggery-pokery I know... you can tweak language far too much really, it's no wonder we humans get so confused with each other all the time.
And yes, that definition would also include interconnects - we work with what we got eh:D
I cringed when I read this oxymoron also. What a 'meritocracy' we must live in.
Yeah excellent comment about the switching resistors. I found a box on ebay which is just relay based volume control it looks good- around 100 bucks. The knob on the front runs the relay. I wonder if it’s any good long term. This has to be the best way to get rid of the impedance problem. As you said as long as the cables can be kept short this method should be superior to an active gain stage. I think for some people dealing with passive solutions might be too inconvenient for them. Also having a preamp that is truly transparent sounding is very expensive.
There are some really high inpedance power amps that certainly give you better matching. A friend had a reputable brand pre amp (old 'sqcool' british)and in that case a passive trumped it completely - though the device was getting a bit old I must say....
Even if you have a high impedance power amp, there is still the issue of the capacitance of your interconnects effectively forming a rc filter, attenuating the top end.
@@paulstubbs7678 What if the cables are short and reasonable quality?
@@paulstubbs7678 Never noticed more top when I went active, and the opposite with the old sqhool replacement, though I have always kept cables as short as possible...
Yes, Paul is right. But like most things Audio; It's specific Recording dependent.
My Schiit Saga + is a Stepped attenuator but it has a Tube for a Buffer?
Hello. I have an amplifier. Naim NAP250 clone card and have made my own amplifier.
When I use different active preamplifiers, the sound is always worse, especially in treble details. I have tried one that only has op amp ic. and no coupling capacitor and a slightly more advanced one with a coupling capacitor on the output.
I find my passive preamplifier to give better sound and more transparent sound.
The passive only has an input selector and potentiometer which is connected to my DAC. which is connected to my computer.
I have done the test many times with the same result.
I don't know why I'm experiencing this.
Naim has a coupling capacitor on the input
It’s interesting if such “passive pre-amp” alters the sound at an audible level. If all it contains are switches and purely resistive components, what comes out is a ratio of what comes in (
I had the 4 then the 5, it is not well at this time.
Passive means changing the impedance of i/p and o/p sources, and setting up series/parallel impedances, not good in my opinion. A fixed matching input (47k) converted into a less than 75ohm output Z with individual resistor(s) for volume is a likely better setup.
Did the "mmm" at 0:19 mean "still a kid but okay"?
Is a passive pre amp really a "pre amp"? It's not "amping" anything and is really only turning down the gain coming from other equipment. Which I can't understand being I have never had equipment that I need to do so and for that matter had to turn most things up.
"Grinding away", power tools, on a carpeted floor and a white couch - Boy are you keen, obviously your wife is many miles away. (I wouldn't last 10 seconds doing that here)
I use a Shiit Audio Freya + with my McIntosh MC275. That preamp gives you the option to run it as a passive preamp, I never use it, sounds lifeless to me.
Isn’t 6db is double the volume? How many steps before ur blown off the seat 😂
Start at 0.5W as first step, not loud enough, and then 1W, 2W, 4W, 8W, 16W, (into good area now) 32W, 64W (Party time) 128W. I make that 9 steps, mine has 8. Honestly, I really don’t think it’s a problem, 3dB if you wish, but that’s a perceptible change, and as I said, I can’t be arsed with getting up for such a small change. The attenuator was more of a development step, the real issue was control of input and output impedance, and the cable capacitance combining to form a low-pass filter, knowing phase starts to move a decade below attenuation. (3dB bandwidth at 20KHz has a phase shift starting at 2KHz)
Actually the sound pressure doubles every 3 dB. It's a logarithmic scale
Has anyone thought about stereo width?
The more resistance you have between signal
L R The less stereo you get. a potentiometer always gives a certain resistance across L and GND and R and GND. since both GNDs are connected, you get a load over L R that varies up and down. you get more and less stereo when you turn the volume up and down. at low volume you get less stereo
If this is wrong, please let me know.