Eldartford, I wanted to say that the amplifier is very sensible so I have probably said it wrongly. So I should have probably said high input sensitivity.
I wanted to say that the power amplifier needs low level signal say 1V rms to reach its full output.
Unsound, thanks for the info.
I have used a passive pre-amplifier and not heard noise when using the Pass Aleph 3.
Also, I have thought that the level of noise depends on the power amplifier circuitry and not the input sensitivity.
For example I have heard noise coming from the Air Tight 211 amplifier. I just want to add that this was the only flaw otherwise the sound was wonderful in all aspects.
Then I read the Stereophile review which confirmed that.
It was not mentioned there for the reason to be the input sensitivity (which as far as I am aware is set at 1V to allow use with a CD output directly).
But now you make me think the reason for the noise is exactly this.
On the other hand the Wyetech Topaz reportedly does not generate any noise due to the circuit - choke filter and so on and still input sensitivity is set at somewhere this level - 0.6 V if I recall correctly. |
Unsound...No problem. I also made a mistake once. I thought I had made an error, but was wrong about that :-) |
Eldartford, thanks. Of course your correct. What I should have posted in regards to Aleko's post is that an amp with a low voltage input may permit more noise to enter. |
In theory I totally agree with you Aleko. However, when using my ears as a guide, I've consistantly found that active preamps sound more musical to me. IMS, IMHO, YMMV.
Cheers,
John |
Unsound...You got that backwards. Low sensitivity means that, to be heard, a signal needs to be strong. Noise pickup is a weak signal. |
Very low input sensitivity might allow noise to enter. |
I hear you Aleko. What is interesting about the theory is that so many folks who have tried passives at some point go back to actives, mostly tubed. I like them both passive (rsistor and tranformer based)and tube actives, but as Guy Hummel of Placette once said to me, and I'm paraphrasing, a thousand theories as to what should sound good aren't worth one good listen. |
Hi All,
I am FOR the passives and not against.
There is a simple principle here - the less is more.
An additional circuit is not a benefit to the whole.
The thing is that the output of many of the sources is not
designed to drive the power amplifier directly.
Then there is the problem of impedance matching and that is why some passives use transformers.
A good tube phono pre-map having a cathode follower stage at the output will drive.
So a selector and ladder volume control (Elna, Goldpoint) at the output will be sufficient for a power amplifier with relatively high input impedance and low input sensitivity (0.5V - 1V).
Why add another circuitry in between?
Let's say that the output tube of the phono is 12AX7 and the input tube of the power amp is 12AX7 as well.
Then these circuits probably match very well.
Some do not.
'Everything should be made as simple as possible, but not simpler' - Albert Einstein. |
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Gregm, ok. Yes, the amps spec is given as 1.1V@22K ohm input impedence. On the CDP, if you meant,"did I read it wrong", apparently not. The HD7600ll's output impedence is given as LINE- 2.0V@10k ohms. I thought the other player was the same, but now I see that a spec is not given. It's an H/K FL8400, one model newer--same DAC, probably the analogue section. So I conclude that it won't work. I am mildly interrested in a City Pulse DAC but I think it has the same spec. But another DAC might be a way to get around it. Otherwise, I assume the Placette active would work. Maybe autoformers? Thanks for the clear, simple explanation of impedence vs resistance.
Atmasphere, I finally got something right. Thanks. I've found a lower cost cable that I like but I probably have $1k in cable easily. For $1k, it probably could have been made balanced. Lynne |
We have a cable industry in high end audio based on the experience of audiophiles hearing differences in the cables.
However most audiophiles don't get that the recording/broadcast industry tackled this problem in the late 1940s and early 1950s, the result being the balanced line system.
For decades, audiophiles listened to inexpensive single-ended gear at home. Single-ended cables do not have a termination standard, so to get around the differences in cables that thus resulted, the cable industry began to develop, starting in the late 1970s, lead by Robert Fulton.
But the balanced line system has the advantage of making an inexpensive balanced cable sound as good or better than the best single ended cable (price no object). The first balanced line audio product was introduced to the high end audio world in 1989, possible because of the increased budget allowed in high end audio, but balanced line has had an uphill battle due to audiophiles not really getting why balanced line is an advantage. I hope my explanation here helps; balanced line exists specifically to eliminate cable problems!
BTW the classic passive volume control problem is lack of bass impact at low volumes. Some controls are built to be very low impedance to try to get around this problem, but that low impedance limits the number of front end products that can work with them. |
Lynne I've got 1.1V sensitivity@22k ohm I take that to be the amp's specs, right? I.e. it reaches its peak when fed (a max) of 1,1V & its input impedance is 20kOhm. That's not too bad... But are you saying your players have an "output impedance" of 10kOhm??? That's too high... I must have misunderstood something. OTOH, 2V output is more than enough to drive the amp -- and then some. You should be able to use a passive attenuator on it. (BTW, it's called "impedance" when the "resisting" factor changes with frequency; it's called resistance, when the "resisting" factor remians constant whatever the frequency) |
I think it is well established that I don't know anything, but if the analogue components could control the cable, then we could not hear the cable. But there is a whole industry based on the fact that cables have a sound. I never understood the reason for this.
I think I'm giving up on the passive linestage for now. Electroid, if you have the ideal components, I think mine are the worst. I've got 1.1V sensitivity@22kohn. And both my players are 2V@10kohm. Not logical. My disposable income went with the stock market, so I'm not in the mood to do a lot of experimenting right now. But I've learned a lot and that's just as much fun. Lynne |
Interconnects are very important w/passives. Especially where HF is concerned. Keep them as short as possible. In my system however it sounds fine at low volume. In fact I find the HF better at lower volume. This could be due to the extra headroom on my LF amp. I use a Placette resitor ladder. My only source these days is a CDP w/2.5 VRMS@ 50ohms. I feed two amps: both CJ SS w/100K input impedance and the same gain although one is 100WPC (HF) and the other 250WPC (LF) My gear has fairly ideal values for a passive setup which is critical. |
Geez, I can't believe people still talk about 600 ohms for any reason. No offense, but that went out with disco... |
Good thing I re-read. Atmasphere's discussion of a preamps inability to control the cable. I reconnected the preamp, but this time I ran the variable output to the preamp in. The sound is improved over the fixed output. Maybe that's because the signal running through that circuit with pot changed the impedence--or resistance or capacitance or inductance--that the preamp cannot control. You have to tune the preamp with cable or any other means you can think of. Yes? ( Atmasphere says that degradation of sound quality at lower listening levels is the same issue, which I thought must be sensitivity. I got that). This might be the most important thing I've learned so far. Lynne |
Eldartford, 600 ohms may be tough, but not impossible. We developed a direct-coupled output, not unlike our power amps, to do the job. I think our MP-1 might one of the few preamps that can drive headphones directly as a result.
Tbg, I've had direct experience with the older Cello stuff. It doesn't seem that it was designed with 600 ohms in mind. |
Gregm, dpac wasn't using a passive linestage; he was using a tube preamp. It would not surprise me at all if I don't understand how impedence works. I'm a gifted dyslexic and I struggle. I go by instinct, and I'm learning as much as I can from you guys. And yes. I am interrested in how impedence works. Please tell me.
John, I understand what you are saying about vintage gear. I have heard of the Audio Research 10 and ll before.
I will read all of this discussion again to absorb what I can.
Scott Endler got back to me. The nude attenuators are backordered and he refunded my money. Meanwhile I've been researching autoformers and transformer attenuators, and I've been waiting for the cable to fully break in. I see the motive now for attempting to achive a successful passive linestage. Without the Sim, I hear the amp, as though for the first time, and it is wonderful. I also am guessing there will be a trade-off with a passive device. What strikes me the most is sensitivity. My amp's sensitivity is 1.1 volt, and the lower the listening level, the more this spec is evident. Lynne |
A 600 ohm LOAD is tough! A 600 ohm OUTPUT impedance used to be normal for tube preamps, but then the tube power amp input impedance used to run 100K and up, so it was probably OK.
Solid state preamps have output impedance of 50 ohms or less, which would be OK even for a 600 ohm load. |
Atmasphere, I do recall many saying that in professional applications using balanced cable the wire is unimportant. I once had the Cello system using Cello Strings and all in balance. We found to our consternation that Siltech balanced cables sounded better than Cello Strings. I have no idea whether the Cello Suite was able to drive into a 600 ohm load, but I suspect that was a design goal. Does this not suggest that there were still sonic differences? I remember thinking that I could not afford to use all Siltech. |
Tbg, thus my final comment on my post!
Several decades back, this problem was addressed by the recording/broadcast industry, for pretty much the same reasons that audiophiles deal with today. The result was the balanced line system, which is actually a standard.
The standard requires that the source (preamp) be able to drive a 600 ohm load. There are several practical reasons for this, not the least of which is that the low output impedance of the source thus has the ability to 'swamp out' the effects of the cable caused by capacitance and other construction issues. The result was twofold: not only can a preamp that supports the 600 ohm balanced line standard control the interconnect so well that essentially the quality of the cable has little bearing on the sound, but also the length of the cable became all but irrelevant as well.
The number of preamps in the high end audio world that support the 600 ohm standard without any sonic artifact (loss of bass and/or dynamics) are very few. Some use output transformers, and that is why the termination standard is 600 ohms, so that the transformer can drive a reasonable load without ringing. If there is no transformer, then the termination is less important.
If you have ever wondered why 'audio engineers' say that the interconnect cables make no difference in the sound, this is why: in their world it is true because they use low impedance balanced lines. Audiophiles can take advantage of this though, as low impedance balanced lines offer the same advantages to them- the standard was in fact created to solve the sonic artifact issues that audiophiles routinely experience. |
Atmasphere, can you please elaborate on the linestage "controlling" the interconnect cables. I have not yet heard a linestage that is "immune" to cable choice. |
If I can speaker to some issues not previously addressed:
There are four functions a line stage has. They are:
1) supply any missing gain
2) provide volume control and input selection
3) provide buffering of the volume control from external impedances
4) (and least understood) control the interconnect cable.
Passive systems provide only #2. Most line stages provide 1-3. If that is all they can do, it will be likely that there will be tradeoffs with a passive, perhaps in the passive's favor. If, OTOH, the preamp is capable of all four functions, then it is likely that the active linestage will be superior.
This is because the interconnect cable plays a serious role in the system. As any passive owner can tell you, the passive sounds better turned up rather than turned down. This is because the passive cannot control the interconnect. At the extreme opposite, a preamp that *does* control the interconnect will be found to be immune to the type of cable and its length.
The unfortunate thing is that you can count the number of such preamps in the high end audio community on your hands with fingers left over, because most preamp designers do not acknowledge the 4th function.
Of course, different line stages exhibit different levels of competence. This definitely muddies the waters somewhat!
This is a good part of why there is a divergence of opinion. There would be none if everyone could hear a competent linestage that can control the interconnect cable, but even that is not likely so this debate will continue. |
Lynne: Pubul57, Why does an amp with a low imput impedence affect the frequency response by increasing the mid's? Why doesn't it simply drive the pre into distortion? P didn't say that -- he pointed to losses in low freq and very high freq. Low input impedance means a lot of energy is required from the source component (the component before the amp) to drive the amp correctly. A "passive" pre doesn't provide energy -- it just attenuates it. So, the task falls on the preceding component -- say, the cdp. Overall, if the system runs out of steam trying to drive the amp... it's distorting. (BTW, are you interested in/do you understand, how impedance works?) |
The old TAP by Bent with its lighting was beautiful and had a remote. I always wanted one. My Tivista CDP w/ its blue feet would have looked great with it!
ET
|
Well I wasn't really saying that age is more of a factor for SS gear than for tube gear. What I was saying is that the the asking price of used gear does not reflect how old an item is. In other words, it's not strictly a case of the cheaper an item is the older it is. Used prices tend to reflect whether an older component has reached 'classic' status vs. just getting old.
Certainly their are 'classic' SS pieces too, like Threshold SA-1 amps, Mark Levinson ML-2 amps, Classe DR-9 amps these units are SS and have reached 'classic' status, thereby holding very good resale value even though they are 20 years old.
Cheers,
John |
Low input impedance with high output impedance from the pramplifier reduces the output in the base and trebles, they roll off. As a result the mids seem to be pushed forward since the balance of the sound is altered from top to bottom. Typically, as a rule of thumb, the input impedance should be at least 10x the output impedance. With the AI3, I think you would need at least a 20kohm input impedance for balanced sound across the spectrum. |
I found that I had an IC about a ft shorter than I was using. So I tried going direct to amp again. With shorter IC I lost the distrtion components that were present with the longer IC. I also discovered that the CD player's volume control is motorized for remote. I cite a very small knob and poor lighting to diminish my embarrassment and proclaim the volume control to be a high quality pot--better than the one on the Celeste. This set-up is significantly better than with preamp, I can tell even though the IC needs some break-in time.
Pubul57, Why does an amp with a low imput impedence affect the frequency response by increasing the mid's? Why doesn't it simply drive the pre into distortion?
I infer from John's comments that age is not such an issue with tubes as with SS. You can simply upgrade tubes and capacitors.
Endler has my money but haven't heard a word.
Lynne |
Thanks, Pipedream, for info. It probably is the hard drive, but my sister and brother have the latest H/K 75W AVR's, and that sound is also amazing as Dpac996 describes. I don't know if I'm upgrading to stay ahead of them or just to keep up. The latest stuff is sounding awfully good. Lynne |
I'm not saying this happened, but my experience with Pass Amps is that they tend to be less than ideal matches for most tube preamps because of their typically low input impedance. This would tend to lessen the output at the bass and treble regions, which is the same thing as saying that it might tend to push the midrange forward, which seems to be what you heard. You SB3 experience seems really interesting, that might be a good next experiment. The hard drive storage "transport" idea is starting to intrigue me. I bet you like the LS26, alot. |
Pubul57,
I have used three different tube preamps with my Pass X250.5: ARC LS15, Cary SLP-05, BAT Vk5i. I have used these with my two digital sources, Marantz SA11S1, and a Squeezebox 3 (with overkill linear PS). I have also used a TVC for a few months as well.
I recently discovered that plugging my Squeezebox 3 directly into the Pass (single ended, with jumper shorting plugs installed in xlr's) results in a very liquid and great smooth sound with well defined images and appropriate size. I thought I was hearing things (no pun intended) and that surely there was no way this combo could sound so warm and relaxing...more relaxing than the recent tube preamp I just had in there. So I gave it a few days and it still sounds really really nice. What does all this mean? Who knows. What is tube sound after all? Does it mean layers upon layers of image density? Does it mean a natural organic utterly non irritating midrange? I really don't care, but if it sounds good, IT IS GOOD no matter what anyone else thinks.
This recent test clearly illustrates that an all solid state chain can yield a nice easy on the ears midrange with vocal heft and texture (not grain). Granted the SB3 is more limited in its resolution and I have no way to hear the SA11 direct, but when the SB3 was going through the tube jobs, the sound was more in your face, more forward, as if the midband was pushed further forward in the speaker plane. I said to a friend that I really feel like i'm hearing the fundamental characteristics of the Pass amp (to the resolution of the SB3, of course) and this result has had a huge positive effect on me (the amp is amazing: rich, detailed, powerful, great sense of depth), and has really pushed me to try a really nice solid state preamp. Perhaps it's just that i'm now realizing that I really like a laid back midrange (as in depth). Perhaps due to the emphasis on the midband that tubes seem to manifest that its too much and not needed with my amp (and speakers of course). Also the bass was off the charts with the SB3 direct, definitely better than through any tube preamp I had in the system. So all of this threw me for a loop and that's why I said what I did about the "warm tube sound" being a mystery to me. Maybe all the pre's I tried with the Pass were just not matching up correctly, but I just bought a Pass X2.5 preamp, and though it's not here yet I look forward to hearing it's effect, or lack there of (I hope) in my system. Pubul57, as you said nothing sounds like tubes but tubes and maybe i'm simply tired of that "sound". That being said next month I will probably look for an LS26 -lol |
Dpac996, what SS do you find has the attributes of good tubes? I would love to stop worrying about biasing and tube replacement, but unfortunatley I can't find SS that does the job. My most recent stab was the Pass XA30.5 which is proabably the best sounding SS I've heard, but still not the sound of tubes (for good or bad). |
Better no different yes. Passives are not for every system. To achieve the best results using a TVC for example would require a CDP with an output voltage of 2V minimum. The input sensitivity of the amp being used should be very low under 1 volt.
There are 3 types of passives; TVC, Resistor based and autoformer. They all do their job. IMO the TVC seems to solve the issue best. Look at the Bent units as well as Antique Sound Lab units. The music First is a winner But over priced IMO. Happy listening.
Pipedream |
Don't assume that you need a tube preamp to give you "warm" liquid sound. I have found that with the right amp and speakers, an all solid state configuration can provide the same "tube magic" and depth of field (plus all the other usual hi fi sound descriptors) tubes are famous for. Tube magic for me has, so far, been a fairly elusive animal...
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I would look for a used Audible Illusions 3A at the $1000 price point - 4-6 years old. But before you go the tube pre route, if you choose to, you need to find out what the input impedance of the HK amp is, to be sure that the tube pre will drive adequately, should not be a problem for most pres, but it will depend on that spec to some extent. |
The ARC LS-7 listed for $1395 when introduced in 1995, so that price seems to fall in line with used older gear. Some of ARC's older gear has higher resale value, like the SP-10 or SP-11. These sell for almost $2K and are over 20 years old.
Cheers,
John |
The Audio Research LS-7 linestage preamp must be an old dog, huh? They're asking around $650 including shipping. I guess you get what you pay for. Lynne |
OK. Got all that. I can send the Endlers back too for 30 days. Yes, linestage--much better. My amp and source is not meeting ET's criteria for the passive linestage. Not looking good. It sounded so good cold. The clarity was sort of a jaw-dropper. Tubes, huh? That's a pretty convincing testimony. Tubes look cool. There could be no cover on my tubes. Lynne |
The Bent Audio TAP, soon to be back in production can be ordered with remote. The old version used transformers (S&B) while the new version will use autoformers (Intact Audio).
Bent also makes a resistor based passive. |
A passive linestasge (not preamp, it does not amplify) is very system dependant. You need high oputput, low impedance sources(my CDP is 2.5VRMS@50 ohms) and high impedance, sensative amplifiers. My CJ solid state amps fit that bill. I'm even able to drive two amps passivly just fine. Then the choice is resistor based or transformer based. There are inexpensive resistor based and more expensive ones. The inexpensive often use the DACT unit and don't have a remote. The more expensive units have a Vishay resistor ladder controlled by a logic curcuit. These have over 100 volume positions and a remote control. Placette uses this setup as does CJ in their preamps. CJ warns of sound gegredation through a volume pot. The Transformer based units can actually add 3-6db gain if needed but never have a remote. Some people like the sound of one type but not the other. I've tried a few of both and use a Placette by choice.
ET |
The Endlers aren't the last word in a passive attenuator, I preferred the EVS, but my reason for using them was to attenuate the gain from an active preamp/amp mismatch. In your case, to evaluate whether or not passive is an option for you, the Endlers will give you a glimpse, but eventually you'll need to move up to something like a Gold Point, Placette, Reference Line, Prometheus, Django, or Sonic Euphoria to hear the real value of a passive. |
uuummmmmmmm....tubessss.....now you're talking.....
If 2 channel is your deal, your really should try tubes. Warm up those cold MN nights. :)
Especially since you have such great tube companies up there in MN, like Atma-sphere and Audio Research Corporation.
There's a first time for everything. If you're shy, it's probably best to start with a tube preamp, as there is less maintenance and tube replacement is less expensive.
A word of warning though, you may find tubes highly addictive, and there is no turning back.
My wife, who is by no means an audiophile, makes very few comments about items coming and going in my system. Most of them aesthetically based, and negative. In the 25 years we've been together, there has been only a couple of times when she has said that something sounds real, and yup, you guessed it, it's always revolved around tube components. Not cables/cords, not cd players/turntables, not preamps/amps, not even speakers. Only tubed components, and sometimes she cannot see the tubes and doesn't even know they are there.
There have only been about 2 or 3 comments in the last 25 years. She says they just sound real, and I agree.
Oddly enough though, she does hate the looks of tube amps with exposed tubes, but she doesn't complain once she hears them.
Cheers,
John |
Pubul57, I'd be more than happy to let you know. I'm isolated here in SE MN. Nobody here knows what an audiophile is. All dealers within 100 mi are busy installing surround sound and care nothing about high end audio. Not that I have anything against surround sound. My sister and brother both have enjoyable systems. I just like 2 channel audio better, and I'm not into the visual. You'd have to educate me all over again with tubes. I've never had any tube gear. I really appreciate all the help. Lynne |
Let us know your impressions. Interesting to see if you prefer the Endlers to your SIM; then there is tubes in the pre..... |
All that "effort" just sounds interesting to me. I'm probably suited to it. Ordered the Endler attenuators. Fun-looking toys. |
I've run source directly to amp, not so good, but that was more likely due to a cheap source. I've run a couple of passive systems, good. The last few years have all been active, a bit better.
Passive systems can be really good, but takes a complete dedicated system approach. You can't just slip in a passive pre, and expect it to work. Everything from source, to cables, to amp, the location of all the gear and the lengths of the cables matter a lot. It takes a lot more effort and reduces your options to make a passive system work well. In the end one has to decide if its all worth it. BTW, the way under appreciated Reference Line passive pre's and power amps are IMHO in the top handfull of gear. I've heard them in many different set ups (though for the life of me, I can't remember the details of even one now?) and not only have they never dissapointed, but, have always drawn me in and impressed. |
Thanks. I'll follow up on all this. Bob, I get parameters from www.enjoythemusic.com/magazine/equipment/0102/pr
Interesting website which relates well to this discussion. Will also give Arn a call at some point. Lynne |
Tomryan, why do you use the RVC between the Joule and amp? What does that gain you? I use to use the RVC with a CAT pre, but that was becasue the volume gradations were so large on the CAT, I needed the RVC for accurate volume control. And I agree, the RVC did not alter the sound of the CAT as far as I could tell, but the CAT sounded way better than the RVC alone. |
I guess the simplest answer is "yes and no". I commit heresy in that I use a Joule Electra LA150 pre-amp with a Placette Passive between it and power amp. Get superb results, I could detect no difference with the Placette in the circuit. |
Hi Arnett, You should give Arn Roatcap at Goldpoint a call if you are looking for some good info on passive preamps and stepped attenuators. I have spoken to him several times and he was quite helpful and great to deal with. The attenuators he sells are quite nice you would be very happy with the quality. I have the newer SMD and the older ladder type with Vishay resistors. I will at some point change the potentiometers in my Marchand bassis with them, I have stepped attenuators in my Marchand crossover. So dont forget, even if you don't use a passive preamp you still need to talk to Arn if your preamp does not use quality stepped attenuators, No Pots.
Just remember your system does need to be "set up" for passives to work, There are several parameters to think about and to address properly before passives can obtain synergy with your system. Only then can you make an informed decision on them.
Bob. |
