I think I've heard that particular setup, and it does sound pretty nice.
Expensive Preamplifiers = Big Scam?
- Thread starter nedgar
- Start date
I think I've heard that particular setup, and it does sound pretty nice.
In my experience, which is best - no preamp, passive controller, preamp - is system dependent. A couple of things that haven't been mentioned here: amps differ a great deal in sensitivity and in input impedance, and cable length will matter more with a passive controller than with a good preamp. Also, truly silent preamps are not nearly as common as they ought to be. Finally, I guess we're talking about line-level sources such as CD - not much in this thread yet about phono sections. In short, to me it is more complex than "the preamp should get out of the way."
Glen B
Super Member
I've owned a couple of preamps with "line bypass" mode that bypassed everything but the volume pot. While the passive mode sounded more grain-free and transparent, music did sound somewhat lifeless and unexciting. "Life sucked out" seems like an appropriate term for what I experienced.
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tubino
A guy with too many tubes
I'm saying that if you want to really do a shoot-out of preamp vs no preamp, then set it up with the system of best dynamic range reproduction to maximize the difference.
I'm saying that all music reproduction involves some compression, but the amount varies a lot. It happens with your source, your amp, your speakers, but some systems are much better about it than others. Someone asked if this is entirely subjective, so I pointed out that POWER compression in drivers is well-recognized figure of merit published for pro gear. That's just one example where the industry recognizes that the actual dynamic range is not merely a function of power X efficiency. This is not controversial, but it's not a common topic of discussion in audio. It *is*, however, key to understanding the appeal of horn-loading drivers, where minimizing excursion for a given SPL means minimizing the dynamic range compression.
Dynamic range is compressed in music reproduction systems, but we can take measures to minimize it, and benefit for it quite audibly. What part of that are you disagreeing with?
tubino
A guy with too many tubes
Yes. Worth repeating.
whoaru99
Epic Member
Sorry, I have to start somewhere, and I thought that's sorta what forums and such were for.
I don't have a bank vault full of money, and the closest "real" hi-fi shop is 150 miles away, so it's decidedly inconvenient to just go check things out.
tubino
A guy with too many tubes
Okay, sorry, that was a bit jerky of me. I probably shouldn't post after a long work week.
It's more about hearing it than reading about it, though, and you don't need to own a $10K system to hear it. If you can set it up on some high-efficiency speakers, though, do it. What are audio friends for, if not to invade their space and disconnect their systems?
The first modern tube amp I bought was a VAC EL-34, Vintage Williamson integrated, basically a good PP amp with "passive pre" (input selector and volume). This gave me a lot of opportunities to hear it without, and with a lot of different preamps. This was a phase where I was trying Dyna PAS, Eico HF-85, lotsa solid state, and borrowing whatever I could. Later I moved up to SE 845 monoblocks with quality attenuators built in, and could try the same stunts with much better quality preamps. The audible differences in dynamics were more noticeable with the better amps. When I moved up to more efficient speakers, the differences in dynamics were still more noticeable. When I moved to 100 db efficient speakers, still more noticeable.
So when I found that a very high quality preamp could be matched by an autoformer volume (Dave Slagle's iron) as long as the impedance matching was not a problem, without loss of dynamics, I was very surprised.
But it's definitely a system-dependent thing.
doucanoe
Registered Audio Abuser
Could be. Oddly enough, my stepped attenuator TVC passive with SET amps and horns has so much gain that I only need to bring it up to about 7:00 o'clock for more than adequate listening level. With other amplification, I have much greater use of the volume control. That could be viewed as "life sucking" to some I guess. Lots of time spent A/B'ing many preamps in my system tells me this isn't so. With emphasis on My System
I couldn't agree more. I think we have a tendency to rely on others opinion of a particular piece. Also, who don't have the slightest understanding of the rest of the system and how they might interact. Selecting a preamp (or anything for that matter) really need to be a real time affair. Unfortunately, that can make it a costly endeavour but most effective imo.
My octal preamp is preferred in my system but it does possess a slightly noisier backdrop. The TVC presents a slightly leaner presentation but I don't feel that it limits dynamics in the least. I have used other passives that I felt did somewhat, but then again that was with different amplification and speakers.
As you pointed out, high sensitivity horns will tell the story pretty quickly if you let them.
Again I agree. I mentioned that I felt my TVC's presentation was a little leaner than my octal preamp. To be honest, the "leaner" could be be better defined as honest and the octal is adding it's own tubular personality.
RC
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x_25
Big Vandies!! Mwahahah...
My suggestion is find a good (doesn't have to be expensive, there is amazing stuff that can be had for $400 and under (even down to around $100 if you look)) pre-amp and give it a try.
Actually, from what I have read it has more to do with impedance matching between the source and amp. Which is one of the jobs of a pre-amp. I know for a fact my one amp and CD player do not like each other without something in between to keep the piece.
Actually, from what I have read it has more to do with impedance matching between the source and amp. Which is one of the jobs of a pre-amp. I know for a fact my one amp and CD player do not like each other without something in between to keep the piece.
Mister Pig
Pigamus Maximus
Well It Depends
The best passive pre-amp I have used is an Electra Print PVA. It uses a nickle core step up transformer in the design, so its not a true passive. However, it does a great job, and isnt too expensive to build.
However, there are several functions of a pre-amp, and a system may or may not do well with a passive unit.
1. Impedance matching between the source, and amplifier.
2. Does the source really have enough mmmph to drive the amp PROPERLY?
Op amps arent the most robust of output devices. Also the amp input sensitivity plays a factor in this. As a side note passive pre-amps can be affectd by interconnect impedance, or long cable runs.
3. Finally, the effect of the volume pot does become an issue. A standard pot varies in impedance as the position changes. Stepped attenuators do not, but thats a more expensive solution.
Can a system sound good with a passive pre-amp? Sure, the PVA sounded quite nice. Does an active pre-amp have the ability to sound awesome? A good one does, and it tends to work in a wider variety of systems than a passive unit.
There are no cut and dry answers here. Passives tend to be more system dependent in my experience. They ar a cost effective route to go, although building something like the Electra Print PVA is still going to cost over a hundred bucks.
Of course this is one barnyard animals opinion. Want a second one? Go ask the goats. Don't ask the chickens, as fowl can never be trusted.
Regards
Mister Pig
The best passive pre-amp I have used is an Electra Print PVA. It uses a nickle core step up transformer in the design, so its not a true passive. However, it does a great job, and isnt too expensive to build.
However, there are several functions of a pre-amp, and a system may or may not do well with a passive unit.
1. Impedance matching between the source, and amplifier.
2. Does the source really have enough mmmph to drive the amp PROPERLY?
Op amps arent the most robust of output devices. Also the amp input sensitivity plays a factor in this. As a side note passive pre-amps can be affectd by interconnect impedance, or long cable runs.
3. Finally, the effect of the volume pot does become an issue. A standard pot varies in impedance as the position changes. Stepped attenuators do not, but thats a more expensive solution.
Can a system sound good with a passive pre-amp? Sure, the PVA sounded quite nice. Does an active pre-amp have the ability to sound awesome? A good one does, and it tends to work in a wider variety of systems than a passive unit.
There are no cut and dry answers here. Passives tend to be more system dependent in my experience. They ar a cost effective route to go, although building something like the Electra Print PVA is still going to cost over a hundred bucks.
Of course this is one barnyard animals opinion. Want a second one? Go ask the goats. Don't ask the chickens, as fowl can never be trusted.
Regards
Mister Pig
whoaru99
Epic Member
Yeah, the effects of output/input impedance are pretty well documented.
I'd like to play with all these different variables, but unfortunately, it's not very practical for me without buying or making things. Not that I can't do either one, but I don't know that it's really worth it in the long run.
A comparison between a fully passive preamp, a zero-gain active preamp (essentially a passive volume control with a buffer), and a standard preamp would be interesting, but it seems the opinion is there is no real conclusion anyway because every single variable throws a big wrench in the machinery.
I'd like to play with all these different variables, but unfortunately, it's not very practical for me without buying or making things. Not that I can't do either one, but I don't know that it's really worth it in the long run.
A comparison between a fully passive preamp, a zero-gain active preamp (essentially a passive volume control with a buffer), and a standard preamp would be interesting, but it seems the opinion is there is no real conclusion anyway because every single variable throws a big wrench in the machinery.
TejasRichard
Babies taste of chicken..
As has been mentioned already, one of the many functions of a pre, passive or active, is switching components. While I realize that there are many passive source selectors out there which could be used in place of a preamp, unless all your sources have some sort of internal volume control (and I've not seen too many 'tables with this feature), you will be forced to use the volume control on your amp....if you are fortunate enough to have one. Personally, my amp has seperate gain control for each channel. I don't even want to think about the hassle of level matching each channel, not just for each component...oh no! But for each recording I play, and for each situation it is played in. No no, give me one knob to play with at a time, and I'm a happy listener. Sometimes adding a component actually simplifies the process...
ps.
While I prefer to use the tone bypass on my pre,
I think we all want to give it a little more gutbucket KICK every once in a while (You know, when you're tired of looking at the same ol' cracks in the ceiling and want a real excuse to install acoustic tile. Or maybe things have been goin real smooth with the missus, and you wanna shake things up a bit...keep'er on 'er toes! That kinda thing.)
So I'll just keep the tone controls around, for a rainy day, so to speak.
ps.
While I prefer to use the tone bypass on my pre,
I think we all want to give it a little more gutbucket KICK every once in a while (You know, when you're tired of looking at the same ol' cracks in the ceiling and want a real excuse to install acoustic tile. Or maybe things have been goin real smooth with the missus, and you wanna shake things up a bit...keep'er on 'er toes! That kinda thing.)
So I'll just keep the tone controls around, for a rainy day, so to speak.
can't speak to passive preamps, but i was surprised how much things improved when i took my old active preamp out and ran my CDP direct to my amp. transients were about as good as you can get, and IMHO that's the biggest factor in putting the the music live in the room with you. unfortunately, this isn't very convenient because i was having to use the attenuators on the amp, and even at the lowest non-zero position the volume was loud. when i got a nice tube-hybrid preamp last week, i found that the end result was much closer to CDP-direct than with the other preamp, and in some ways it was better than the CDP alone. the convenience of its remote control tipped the scale for me, plus i'll want source switching fairly often.
i'm not exactly an expert, so please feel free to correct me where necessary, but i don't see how you can get better transients and/or wider dynamics by adding preamp circuitry, passive or active, to the system, unless it is a cabling/impedance issue or the CDP PS doesn't have enough oomph to drive the amp. i guess you could purposely design your preamp to have non-linear response, which is probably how so-called dynamic range expanders are supposed to work. i will also say that i think that sometimes people confuse better dynamics with what is really enhanced (i.e. non-flat) frequency response.
i'm not exactly an expert, so please feel free to correct me where necessary, but i don't see how you can get better transients and/or wider dynamics by adding preamp circuitry, passive or active, to the system, unless it is a cabling/impedance issue or the CDP PS doesn't have enough oomph to drive the amp. i guess you could purposely design your preamp to have non-linear response, which is probably how so-called dynamic range expanders are supposed to work. i will also say that i think that sometimes people confuse better dynamics with what is really enhanced (i.e. non-flat) frequency response.
tubino
A guy with too many tubes
It's kind of interesting to look at the sonic effects of extreme pre-amps. If you've ever attended a demo of Sakuma with 845 driving 845 driving PP845... or closer to home, if you've ever used Ampex 350 preamps, with transformers and octal tubes... you know what massive overhead can do. Especially if it's carried out through the rest of the chain out to the speakers. The only room at AK Fest 09 that I'm aware of that went this way was the Classic Audio Loudspeakers room. It takes effort.
EDIT: To oversimplify, the effect of going for extreme headroom is the opposite of removing a preamp, if there's still any room for a broadbrush generalization here. Anyway, that's been my experience. Overhead in voltage & current gain is what you can get with a great preamp... impedance matters a lot for broadband response, but there's something else at work too with dynamics.
EDIT: To oversimplify, the effect of going for extreme headroom is the opposite of removing a preamp, if there's still any room for a broadbrush generalization here. Anyway, that's been my experience. Overhead in voltage & current gain is what you can get with a great preamp... impedance matters a lot for broadband response, but there's something else at work too with dynamics.
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Tubino is right. Insufficiant gain control with a passive. That's why preamps exist. Tone controls are nice, but they add distortio to the signal path. You need a preamp because you need the gain. Poor gain control equals limp weenie sized sound.
doucanoe
Registered Audio Abuser
tubino
A guy with too many tubes
Well, yeah, but remember this tubino character was ALSO claiming NO limp-weenie sound when using an autoformer alone twixt CD player and amps... so go figure.
When I get settled down with speakers, I'm going to build a really GREAT preamp using an autoformer volume control with low-mu triode gain stage and cathode follower on either for righteous goodness. Just you wait.
Jon_Logan
Addicted Member
There is no impedance matching at audio frequencies. The output impedance is low and the input impedance is high.
The output level control of a CD player is buffered after the level control, so there's no issue of the controls angle giving a higher source impedance to the load with different level settings.
Op-amps are robust enough to drive a cable and an amp's input impedance. When an op-amp does have trouble does have an issue driving some load capacitance, the designer usually inserts a 10 ohm or so source resistance that isolates the op-amp from the capacitance. If there was trouble with the source unit driving an interconnect and input impedance, the same situation would exist driving a pre-amps input too.
whoaru99
Epic Member
No, not impedance matching per se. But, you want (typically) a low output impedance feeding a high input impedance. I think the context was in regard to a passive attenuator where the input or output resistance differs with the wiper position.
In that context, an active preamp does "match" impedances, through its buffering action, by maintaining a fixed high input impedance and a fixed low output impedance. Although, I do admit that is a somewhat clouded use of the term "match".
In that context, an active preamp does "match" impedances, through its buffering action, by maintaining a fixed high input impedance and a fixed low output impedance. Although, I do admit that is a somewhat clouded use of the term "match".