Why not try a pair of Endler or EVS attenuators. These are stepped attenuators that include custom RCA jacks. One end is male and plugs into the RCA inputs on your amp. The other end is female and is where you will connect the output cables of your source. This should give you a good idea of how a resistor based passive device will sound and they are relatively inexpensive to try. I believe one or both brands may come with a trial period, so you can return them if you don't like them.
I personally prefer transformer volume controls as for the most part they avoid the impedance matching issues of resistor based passives. I've been using a custom built unit using S&B transformers for a while now with excellent results. |
John, you're right. The Placette active is my goal. I need to hear a stepped attenuator. I don't have any. Newbee asks much better questions. Lynne |
I've always wondered, when discussing passive pre-amps, with and withoput transformers, what is the effect of a passive pre-amp without transformers, which has a varible output impedence from 50K ohms to near 0 ohms at max volume rotation, a point where it should be, for all pratical purposes invisible to amp? How does the sources output interact with the passive pre in relationship to the passives output, or does it? I've never understood any of this. Is it meaningful at all?
Does a passive with transformers present a constant output impedence to the amp? Is it affected by the sources impedence?
Or are these just meaningless questions? |
I'm sure there are differences between passives, just as there are differences between actives.
I have to ask though.....why?
Even though most here have recommended active preamps, you seem predisposed to passives. So why even ask? Just go ahead and buy the passive and form your own opinion, the same way the rest of us did.
Cheers,
John |
I did not make that question clear. I think it was a dumb question. It seems to me that all passive preamps of decent quality would be equal in terms of how the amp sees them. If one didn't work, none would. (I'm not including the Placette Active in this group). I tend to try taking the lower cost route and that usually doesn't work out and then I buy the piece I should have bought origianlly. I know better, but there I go again. If the cd player direct to amp didn't wrk because of the inferrior volume control then a passive would solve the problem. The Goldpoint for sale would be a somewhat low cost experiment. |
OK. Are there likely to be differences in passives? There's a Goldpount for sale. Lynne |
1. The Placette attentuators (on both the RVC and Active) are arguably the finest ever made.
2. THe 40 kohm spec might (not sure about that) be true for the Placette RVC, not the "Active" - the active will drive (in terms of impedance matching) any amp you can find. |
OK, Bob. Thanks. Last night I searched Placette under discussion forums. One member said that a passive preamp needs 40 k ohms input impedence from amp. That might help explain why some people are happy and some are not with passive preamps and goes to Eldhartford's rremarks on many amps going into clipping. So I might not be going passive but I will check out the attenuators. Lynne |
Hi Arnettpartners, When doing a passive preamp the type and quality of the attenuators are critical, You may want to check out Goldpoint at http://www.goldpt.com/ for some info and their products. Even if you dont go for a passive preamp it is good to change all potentiometers in any of your equipment to stepped attenuator types for much improved channel balance and clarity.
Bob |
Yeah. Cool. And I don't know how much of the hobby is having a good system and how much is having good knowledge. That's part of the fun, too. Lynne |
01-07-08: Arnettpartners
Pubul57, Thanks. I'll check it out. If I spent that much I would have to never tell anyone. Lynne That's part of being in this hobby Lynne..........we take our secrets to the grave...... :) Cheers, John |
Pubul57, Thanks. I'll check it out. If I spent that much I would have to never tell anyone. Lynne |
I see there is one on sale for $2995, which is not a bad price. The price jump to $7000 was very recent and a very large ump from the previous $4995 price. So most used units were probably bought for much less than the current list -- that 2995 does not look to bad if the unit is in a good shape - they come with a 20 year warranty, so it is not like it is worn out, or wearing out. |
Eldartford, I later got distortion components. I only played two cd's that night after setting it up, and I thought that it was an improvement over using the preamp. But the following day when I tried other cd's I got a harshness that had not been present. The system had been powered off for a few hours before set=up while I was setting up a new cabinet. So if it was because it was relatively cold at first audition or the cd's I used or my own focus on the improved silent background and clarity I don't know. I guess I should try it again. I wondered if the inferrior output control makes it a poor reference. I'm a little frustrated right now because I think I'm zeroing in on a really good system. But I don't have anywhere near 7k for experiementing. I read partially the review in Stereophile on the active Placette. The reviewer is bananas over it. I guess the Placette is on sale right now for 4k. I just discovered here that your email address is available. Lynne |
Arnettpartners...Just curious...in what way did it "not work"? |
It didn't work. Back to preamp. |
Since I don't have the $7000 maybe somebody will start manufacturing them for a fraction of the cost. I copied your response, Eldartford. Last night I tried bypassing the preamp with my H/K HD7600ll which has a variable output option. This player is so old that probably no one knows it anymore. In the late 80's--early 90's it was considered as good as any player on the market, so it's not a terrible reference. I tried this years ago with another system and the result was so horrendous that I didn't consider it with this system until last night. It sounds good. I get the quieter background and improved clarity. It might sound more like my brother's and sister's surround systems with less dynamics (but what is dynamics?) Maybe the music is slightly "pinched". Not sure. The manual volume control feels like a good pot but it's not motorized. I set it at half volume and varied the volume with the remote, and this volume control is of inferrior quality, I assume. So I don't know what these settings are doing for it or to it. All I know for sure is that preamps are an annoying necessity. Lynne |
The Placette "Active" approach of following passive switching and volume control functions with a unity gain buffer seems ideal to me. In practice most preamps are operated at less than unity gain overall although within the unit there may be many dB of gain. Most of it is discarded in the volume control. Most disc players, for example, have a nominal output of 2 volts rms, and 2 volts would drive most power amps into clipping.
When I built my home brew "passive preamp" several decades ago I also built what I called a "line driver" which was a unity gain buffer amp with high input impedance and low output impedance. This was necessary when I changed power amps from tube units with 250K input impedance (high even for a tube amp) to SS amps more like 20K. I was very aware of output impedance requirements from my work as an aerospace systems engineer where it was necessary to transmit both analog and digital signals through as much as 300 feet of 20-year-old wires. There was always a circuit dedicated to this "line driver" job. |
Thanks to absolutely everyone for the discussion. I don't know when I've learned so much about audio. I'll bet it's true that receivers and integrateds have no active preamp. That's how they sound. All of you filled a big hole in my audio experience. A lot of things came together as a result. Cheers. Lynne |
Pubul57, I did try the Placette "Active" briefly and did like it better than the totally passive unit. I also thought there were better active line stages.
I should say that I certainly have heard active units that were worse than the passives, the Crown 150IC and several others come to mind. The top passives that I have had are the Audio Consulting Silver Rock and the Top Dog, which is no longer made. |
FYI - the Placette "Active" (which is a zero gain pre with a buffer)has an output impedance of 10ohms or so and will "match" with any amp input impedance and, I'm told, almost any length cable. Of course, I think it is selling for $7000 now. Some may argue it is not a passive, but it has no gain stages which is a primary reason for the quiet and transparent quality of most passives. |
Entrope, yes, you are correct. I don't really know whether anyone has ever measured this, so it is really a personal judgment or a comparative judgment. I find that I grow bored with the music using a passive, that I find myself not shaking my foot in time with the music, and that is just lacks the leading edge of the music. |
Perhaps I do not understand what is meant by dynamics. My passive preamp/Atmasphere setup seems to have great dynamics to me.
By dymamics is it the range from high to low and speed in shifting from point to point in that range?
Or is it something else? |
|
I disagree with all the passive preamp folks. Saying things like, "It will be quieter," is not always true. My Fire preamp is black background as any passive, arguably more. |
Lynne, the "rule" is 1 to 10 (line stage output impedance to amp input impedance, so you should be okay.
I cannot stand the lack of dynamics on passive volume controls and suspect that is the mismatching of the source output impedance through the passive volume control to the amp input impedance. But it really doesn't matter as five attempts was enough, I am sticking with quality active line stages. |
Thanks. That's what I thought. The 7.1 has an input impedence of 22k and the Celeste has an output impedence of 120 ohms. I have no idea how synergistic or unsynergistic that is. Lynne |
Forgot to mention--yes, I'm exclusively digital, if that matters. Lynne |
Sure. Especially when you match most tube pre-amps with SS amps. One must be careful to make sure the pre-amps output impedence is sufficiently low to properly drive SS amps which often have low imput impedences. |
Good question.
You bet impedance is an issue, actually the issue when pairing a pre and an amp. Impedance matching - or mismatching - between the pre output and amp input is the key to a successful pairing or two boxes that just aren't happy together... Call it synergy =)
A great deal can be found on the subject by those both more technical and erudite then I am - all I can contribute is that its great when it happens and noticeably not great when it doesn't. T'aint no subtle or illusory thing. |
I will show my ignorance (more of it). If impedences are an issue with passive preamps, then are they also with active preamps? Lynne |
Of course "great gain, improved dynamics, vivid contrast and improved bandwidth" is not distortion. But these do not "enhance" (add to) the input signal. They preserve it. Anything added is distortion. Inaccurate, a preamp always adds something to the signal, it's an amplifier. The question becomes one of improved sound or not. Albertporter...Just as tube circuits are known to modify the incomming signal by generating harmonics which some think are pleasant, I am suggesting that the extra circuitry of an active preamp may be doing the same thing. Tube or transistor, both add to the signal, nothing is perfect. It then becomes a question, do the benefits outweigh the negatives? |
Albertporter...Just as tube circuits are known to modify the incomming signal by generating harmonics which some think are pleasant, I am suggesting that the extra circuitry of an active preamp may be doing the same thing. I think this is an idea to consider: not just semantics.
Of course "great gain, improved dynamics, vivid contrast and improved bandwidth" is not distortion. But these do not "enhance" (add to) the input signal. They preserve it. Anything added is distortion. |
Eldartford, My exact comment about passives: Zero gain, zero contrast and zero dynamic enhancement from the original signal. Isn't zero dynamic enhancement the opposite of improved dynamics? I don't consider great gain, improved dynamics, vivid contrast and improved bandwidth as distortion. My meaning was clear and exact in both situations. You seem to be more interested in taxing peoples comment with semantics than contributing to the knowledge base. |
By the way, an integrated amp or a receiver essentially has a passive preamp in it (without the external interconnects). Like the Ayre AX-7e. |
Albertporter...First of all, I do agree with you that an active preamp usually works best. I guess I would agree with your original comment if it said "lack of signal degradation" rather than "signal enhancement".
I don't know when passive preamps became commercially available, but several decades ago I made one to suit my particular (rather unique) matrix multichannel system. I had plenty of gain, and my solid state source components had the low output impedance to drive tube amps having high input impedance.
By the way, an integrated amp or a receiver essentially has a passive preamp in it (without the external interconnects). |
Well said: "that depends on the tonal/sonic quality preferences of the listener". I also experienced that sense of amazement[?] when I first used passives, because they certainly are different, but ultimately I felt the need to go back to active, I suspect this is a very common trajectory. ok, 65%/35%. |
BTW, I failed to note in my post above, I have been using a Wadia direct to an amp and one thing has become clear from my experimenting with it thru a passive and active line stage. The active line stage was additive and the passive was subtractive (better or worse is not the issue as that depends on the tonal/sonic quality preferences of the listener). If the synergy is right for you, and you're into digital this could be the way to go.
Probably obvious and redundant for most here. FWIW. |
I have tried five different passive units. Initially, I am always struck by the purity of the passives, but when I put in a quality active, I end up selling the passives. They have no pace or dynamics of live music. I seem, however, to be the exception in that I have had a solid state line stage for the last five years, the H-Cat P-12. Repeatedly, I have tried tube preamps, which I had always preferred, but always come back to the H-Cat. |
Hello, I have been using a passive preamp for the last eight years or so and had tried them prior to that. I was also trying SS and tube preamps till the passive "won" the contest for me. No loss of dynamics or sonics but improved clarity and resolution with decreased noise and colorations.
I have no need for switching as I only use a TT, though that is possible with a passive, I use "naked" attenuators (no switching). Why add unnecessary gain, colorations, expense, complication and noise if you dont need the gain?
Now it is active 12 to passive 7. Not as terribly lopsided as one would think.
Bob |
I have Wyetech Topaz 211 tube mono amps and had the Placette pre in my system for several months and although I appreciate what it does , it was a sheer pleasure to replace it with a good active ( Audion 2-box linestage ).
The music is now alive with lots of impact . |
When I asked the question, the passive seemed more logical to me. Now the active seems more logical. I'm sure I will experiment when I have the opportunity. I think the 7.1 is probably 22k (just got in from delivering a calf and am too lazy to look it up). H/k usually is although this one is Madrigal. Thanks for the interesting disscussion. Will research Placette and Manley and Joule for sure. Don't stop. It's very interesting. Lynne |
A really good active preamp will actually be more transparent than a passive preamp for all of the reasons mentioned by Albert.
Using a passive preamp places demands on source components that they are often not ready to meet. Even with the rare capable source and good impedance match, a passive unit is a pure impediment or drag on the source and the signal with no upside.
I will go a step further and say that in the best systems the preamp is often more of a determining factor than the power amp in the overall sound quality of the system. |
Passive worked for me but I carefully selected a CDP and amps to match. Half volume will shake the house. First impression was incredible tranparency but that something was missing. After going back and forth between SS. tubes and passive several times, all the passive was missing in this combo was noise, distortion and embellishment.
Talk Thunder 3.1b - 4.2V XLR/ <100 ohms
DIY TVC (Bent/S&B) 0 gain
dual, bridged Plinius SA100 - over 38 dB gain
Genesis 350's - 96 dB
combined with the Genesis servo - that's a lot of wattage |
Interestingly, I had the Placette RVC and the "Active" which I owned between a CAT,Lamm, and now a Joule. The Placette's were excellent (we are hairsplitting between some very fine equipment), though I preferred the Placette "active"(it has no gain, but a buffer to ensure it can match with pretty much any load). Given that, I still ended with the Joule as it made the music more organic and more full bodied than the Placette approach (one of the finest IMHO); whether I prefer "distortion" or not I don't know, nor care, I'm more engaged with the music through the Joule. Maybe it is the difference between hearing into the recording and hearing into the performance - if that makes any sense.
I'm not sure if proper matching would really address what did not totally satisfy me with the passive, as the Placette Active has no mathcing issues (except possibly gain with some systems) and it was clearly better than the RVC in my system, not close in my view; it will satisfy many listeners. Experiment - but I do think the input impedance of most tube amps is proabably an important issue to good "matching". |
I currently run passive and here's why:
1. It squares with my system philosophy of simple, short signal path.
2. I only have a single source and don't need source selection.
3. I can't justify another set of interconnect cables, power cable, tubes, and the linestage itself. I use Cardas Golden reference cables and, while not the best, I'd feel compelled to use the same on the preamp.
So, for me, it just doesn't make sense to add another $2,000 to a system that only has $2,000 speakers, $1,200 amp, $2,500 phono stage, etc. |
I'm suprised that at least the with this group, it seems more like 80/20 for the active - not that it necessarily means anything, but it does seems to be some form of consensus amongst different listeners who have experience with both approaches; but eventually, you really have to try it to know if the passive works for you. |
All preamps will add a coloration. Recording Engineers know that instictively when going to grab Neve, API, SSL, Manley, etc. Most peoples experiences with passives aren't that pleasant due to impedence mismatching and the neccesity for high quality internal components. Done right it works well. My home system still uses a "dual mono" PS audio passive that I keep going back to again and again for it's sheer pleasant musicality.
If you want great sound with little thought or effort avoid the passives and pick up a Manley. |
Pubul57 got it right. The only thing I would add is when discussing passive preamps, Placette is in a class of it's own.
No other passive is simular in design or parts to a Placette.
Hence no other preamp sounds like a Placette.
IMHO and a great many others, anyone saying they've tried passive preamps without trying a Placette, really has no idea just how good a passive preamp can sound.
Don't take my word for it. Order one, and you'll get a 30 money back guarantee to find out for yourself. |
Eldartford Albertporter...You criticize a lack of "enhancement from the original signal." Wouldn't that be *distortion* of the original signal? Pleasant perhaps, but not "transparent". I don't consider great gain, improved dynamics, vivid contrast and improved bandwidth as distortion. In fact, that's exactly what I'm looking for in my system. In our group, tests between state of the art passive against excellent preamps (RE: Manley Steelhead, ARC REF, Aesthetix Callisto, Audio Note, etc) the active always won. |
