Discussion in 'Turntables' started by IGSTER, Feb 2, 2018.
Do preamps enhance sound quality? What's YOUR opinion?
Preamps of better quality have better SN figures, less cross talk, more headroom in the output stage. They also have dead quiet phono stages with accurate RIAA equalization. Each of these things lets the source music come through with as little colorization as possible. You do need a good set of speakers setup well in a good room before you an evaluate any piece of equipment.
Sound is bad as bad as the worst component in the chain. So it means that if you have bad source then no one preamplifier can do better sound and vice versa, if you have bad preamplifier and good source then you also have bad sound.
I think the preamp is more of a factor on sound than the amp.
I agree with Sturgus. When using a preamplifier for a Cd player or a DAC nothing is being amplified. The source signal is "only" being attenuated. But Ooh La La a lot of colorization happens there. Buy a few different preamplifiers (used) and see for your self.
They do sell $50,000 phono preamps, and customers buy them. Surely there must be some reason for this...or maybe not?
Yes, there is a reason- more money than sense.
Well, there is that. But if you listen to them in a system you are familiar with, you might find that they produce very pleasing results, even though they all sound very different.
According to high-fidelity orthodoxy, no component can enhance a signal, only degrade it. That doesn't really explain phono preamps very well, but applies better to line preamps. My TVC does a good job of doing the least damage, imo. If I come across a significant fraction of $50000, I'll report any enhancement I hear...
Every powered preamp has another board in it to re-power the line level inputs and give the line out to the amplifier the correct output impedance and current to drive the signal down cables. Tone controls are also powered and normally, there is a board for that. Record output usually do have the signal from the line input direct to it, unless there is a buffer in the circuit, then no signal will pass unless the preamp is powered up.
Powered phono preamps have a amplification board in them to get the signal up to line voltage (like your CD player, tuner), and also has an RIAA circuit to cut the treble and boost the bass to get a flat frequency response. In case you didn't know it, records have the bass cut very low and treble boosted very high. This helps the stylus track the bass better and the other end helps to reduce surface noise. IN other words, the records are RIAA encoded and the preamp "decodes" the RIAA signal, bringing it to a normal (flat) frequency response.
I assume you are asking about phono preamps, right? If not, this thread is in the wrong forum.
IMO, a good preamp should not enhance the sound at all. It should be neutral and not "color" or enhance the sound at all. That's what tone controls are for.
Phono preamps are necessary to add the RIAA equalization curve.
If they have enough knobs, sliders, switches and buttons they do !
They enhance, compress, expand, reverberate, equalize, boost, temper, transform, shift, Image, color, revise and correct the music.
If you get the right one, it will magically transmogrify your music from its present dull form into a futuristic, metamorphic permutation that will reveal the real afterlife of sound.
So carefully choose grasshopper
One would surmise that the best preamp is neutral.
Only if they color the signal being fed to them.
It all depends. The same RIAA preamp circuit fitted into a separate box or built into an integrated amplifier/pre-amp should be ............well.......the same.
This is very modest gear, but I have a U-Turn Pluto phono preamp and an 80s Rotel RC1010 stereo preamp with a built in phono stage. I decided to see if I could hear a difference and whether I preferred one. I thought the difference was rather pronounced and was surprised I preferred the Pluto, but just the age difference may be a major factor.
The phono preamplifer stage must do two things at once.
It must boost the low voltage level of a MM type cartridge, which will put out a voltage in the 5 millivolt range.
Or if using an MC type cart, which will have an even lower output level, in the approx. 0.3 millivolt, to 1 millivolt range.
This is why some of the higher end preamps will have a switch to switch from one type or the other.
They switch the internal network to boost the signal even more, plus they use a slightly different load in the circuit due to the MC needs.
Most turntables came equipped with MM type carts.
And the preamp must invert/reverse the RIAA equalization curve that is used to make records.
So there is some electronics magic that must be done to make this work correctly.
Back in the 70’s a mathematician named S. Litpshitz showed that many of the Phono preamp networks used at the time to invert/reverse the RIAA curve were using incorrect network equations!
Which gave less that accurate flatness curves.
Add to that, the fact that consumer grade equipment manufactures used cheap standard 5% resistors and maybe 10-20% grade caps, also those old (60’s, 70’s) transistors likely have a higher noise spec. than today’s transistors in their input stage networks, and you get less than perfect RIAA flat responses, due the variation in the components.
Todays phono preamps should have been designed AND simulated on software to see if they return a flat RIAA curve.
Picking tighter spec’s on the Resistors and Caps is also a requirement to get the theoretical response.
So a preamp can have added ‘color’ due to an inaccurate inverse/reversed RIAA curve.
This will be due to several factors, such as bad RIAA network design, poor matching on the R’s and C’s, and noisy transistors.
Or due to those still not understood electrical effects (some would say magical) that people say adds color.
The basic question is always the same in my mind.
Which is: Can you hear a difference?
If yes, then which do you prefer?
Do fat babies fart?..........Absolutely!
Discussion on PHONO stages please state that as such seeing as a Preamplifier is a totally different thing.
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