Thank you Paul for yet another excellent explanation in your series. I really like how you can explain the subject so simply yet with a technical perspective that makes understanding the technical aspect so much easier. Brilliant.
I've been looking everywhere for a clear answer on preamp ideal gain and your video just came up. Turns out I was kinda doing the right thing without knowing (although I'd say I was at around 80%). I will try turning in down a notch at around 70%.
Good point. I have a bhk preamp and stellar m700 Power amps and had the problem that the gain was too high. Because of that the volume at normal listening level was set to 10-20 on the preamp and the speaker was noisy. When muting the preamp that white noise disappeared. Solution was to put passive Rothwell attenuators between the preamp and the amp of -15db.
man, tha gain on my conrad johnson is out of control. in my amps that have no attenuation, its loud as hell at 9 o clock, and thats with my amps set to 1.4 input sensitivity. i cant make it past 8 comfortable runnin into one with .775 sensitivity. i blut some inline attenuators for my amos that dont have em built in.
Mr. Tea: This may help you! I have a Complete PS Audio system {as of late last year, B 4 their speakers were released!} Including the Top CD Transport, & Perfect Wave DAC, &, all AudioQuest Cables! {Had to sell two of my young children in order to afford them!} I DO NOT have the Preamp, because: I want a, `straight wire with gain,' & the DAC has two output levels: approx. 0.2 volts, and, `ten times this,' at about 2 volts, within the range Paul mentions! I also have the M-700 power amps, lots of power, into Klipsch speakers, very efficient, about 97 dB sensitivity. Headroom: We want Headroom! And, I don't mean a Navy Restroom! With the .2 volt DAC output, powerful amps, efficient speakers, this is a good combination. EVERY stage of signal processing can add noise, distortion. I have theories about how the preamp can make the sound, `sound better,' improve the sound! So, you may be, O. K.! Any thoughts? Keep & read the pamphlets, literature which come with the equipment! Ask questions! Chow! {Even Paul has said, in the past: "You don't need a Preamp!"} {Try your system without the Preamp! Send it to me! I'm doing you a favor - Right now, today, with the embargo on Russian products, tubes are very expensive! Save yourself! I'm willing to help you!}
@@vinylrules4838 Well, yes & no! Years ago, I recorded my bothers, in a Church: Brian on trumpet, Charles on drums, 4 track reel, separate channels. For the cymbals: had the level on the VU meters, barely move! This is because, some instruments really don't have a typical, `average level,' are actually very peak - y! Pianos, too! Worked out, sounded fine! The analog VU meters unless they have special `Peak Retention circuitry,' can not respond to very brief high peaks. You are correct, are a, `guide,' must be interpreted!
Also looking up the distortion for your preamp would be a good place to start. Poorly designed amps/pre will have higher distortion at either of their limits upper/lower.
Even the cheapest handheld or analog oscilloscope can tell you everything you need to know pretty readily. You can see exactly what your peak output waveform voltage actually is and then adjust gain to get your correct 1 - 1.5v peak to peak line signal strength.
The volume and input selector are both bypassed on my preamp. The volume is on the power amp and my dac is hardwired with solid core wires straight in the pcb's input. These mods yield the best result for me.
@@Sac_slappper_4rce That doesn't sound bad to me. Did you consider customising your DAC to your taste (provided it's not a multilayer smd PCB kind of DAC without any schematics)?
@@edmaster3147 I swapped the opamps to Burson classics but it's getting old and I don't think further upgrades really worth it. I should just get another unit but can't afford any new toys at the moment. Well none that I really want anyway.
I use a unity gain pre(that can be adjusted ) - 2 O clock is giving more than needed - my thought is the less gain you need the quieter the noise floor.
That's a balancing act though. Some amplifiers have very high input impedances that are a lot easier to clip if you dont run your power amps a bit more wide open. Can make it harder to keep a lower noise floor while gain staging. However most modern solid state amps this isn't something you have to worry about. With tube and Class A power amps this can be something worth keeping mental notes on though. Although most modern amps have inputs pretty hard to clip, that doesn't tend to apply to truly high end and boutique stuff where it's expected for the customer to know EXACTLY what they are trying to do with their equipment.
i selected minimal gain after all emprovements of anything i could 🧐 at first i missed high freq "cloud", same as i was when changed accuphase dp700 to 900/901 🤔 but than you adopt and its obviously min gain at preamps and amps for sure 🧐 its quite beter 😂 just add more volume at preamp and its 😇
I have always wondered why you need a minimum of 10K input impedance. That means you are driving the power amp with less than 100µA. Can a pre-amp not deliver more than that?
Most modern preamps can directly drive loads down to 2k with some loss in the low and high end freqs. 10k is recommended min for flat response 20-20k range.
Unity gain is a gain of 1. In other words, there is no gain. A preamp with unity gain is (normally) not an amp, but a buffer and only attenuates the signal. Otherwise known as a passive preamp.
On a good pre-amp design the "unity gain" (input=output signal strength) point occurs between 12 and 1-o-clock on the volume control. It varies slightly due to fact that many pre-amps use an "audio taper" (logarithmic) volume pot. In other words if you inject a signal into the "aux" line input and set the volume control to 12 (or 1-o-clock) AND connect the output to a 10k load (or near 10k) then the input and output signals should be identical. The frequency response curves of many pre-amps are measured here. At this point the pre-amp is just a buffer circuit. zero db of gain with high input impedance and low output impedance. Distortion should be non-existent.
Dad, what is a preamp? Son, it's the box connecting a power amp to your vinyl record player, CD player, cassette player and tuner. Dad, I don't have any of that, what is it?
Interesting topic! But unfortunately preamps rarely have gain switch. For example, my preamp has 10db gain, power amp is 26db, and input sensitivity is 0.77V. I have to use XLR Attenuators on power amp input because I can't go pass 10% of volume on preamp (speakers are ~90db). What to do in that case? I still find confusing those 0.77V sensitivity - source input into preamp is standard 2V, and preamp can add its 10db gain on top of that, so will be much higher than 2v, right? And power amps have sensitivity of 0.7-1.5V, so sounds like it will always clip (but it doesn't).
Weird. I have similar gain specs on my home system (actually my Preamp has even MORE gain) and my normal volume control setting is between 11 and 1 o'clock. (It's quite loud at 1 !). You mentioned XLR connections. What it sounds like is that you might be directly blending a balanced signal into an unbalanced connection somewhere. When this happens the gain is doubled. When a balanced signal is converted to un-bal it's amplitude must be cut in half so there is no net gain in the conversion. The amp itself could be doing it by NOT properly detecting the "balanced" connection. That would explain the high signal at the 10% volume point. Your second question (concern) has to do with aux input values. The signal path in most pre-amps is like this: (1) input selection (2) EQ or phono (3) Volume Control (4) 10-20 db line amp (5) output buffer circuit. So your volume control is attenuating the the AUX input BEFORE your line amp brings it back up by 10db. The 2volts is the maximum (Redbook) voltage that the aux input should ever "see". Your volume control setting will then reduce it a lot..probably down below .2 volts, then add in 10db of gain and your at .6 volts (almost full input voltage!). So what your pre-amp does (and what most pre-amps do...) is essentially attenuates the 2 volt (max) signal from a high input impedance down to .77 volts (max) at a low output impedance (around 100 ohms) and sends it off to the power amps inputs. Your pre-amp (and mine too) are just fancy active attenuators when connected to a CD (or hi-res, or SACD) player. Hope this helps.
So many questions that audiophiles have, could be answered by acquiring an inexpensive oscilloscope, and learning how to use it. If you're spending thousands on equipment, why not spend a few hundred for a USB scope module that works with your laptop computer?
No, standard line level inputs at consumer audio equipment isn't rated at 0dBV (1 Volt), but at -10dBV (0.316 Volt) instead. en.wikipedia.org/wiki/Line_level#Nominal_levels
