After many painful and time consuming experiments,I have to believe that single ended and balanced components does have mating problem. It seems like many balanced only component were designed to match with other similar or same manufacturer component only. Thus, I think I better trade in my preamp or power amp to set up a balanced or unbalanced only system.
The Maggie is something I cannot live without. So do the CAT SL1. And the Ref 150 seems doesn't up to the task to tamed the Maggie. So a more powerful single ended tubes or solid state amps would be a sensible replacement. Of course, before buying, I will have the dealer brings them to my house for audition to make sure there are no more distortion with the new set up.
Hopefully someone have good single ended amp in mind which could drive the Maggie efficiently and match well with the CAT can offer some suggestion.
BTW thanks Almarg, Syntax, MrDerrick, Zd542 and others for your kind assistant on this issue. |
Referring to the Audio Research BL-1 and BL-2. |
If you don't have a pair, see if someone will lend you a fully balanced IC. Be careful not to get a SE cable terminated with xlr connectors. You need a cable that's really balanced. Use it to connect your Wadia directly to your amp. If you do that, the noise will probably go away. Also, you may have to go inside the Wadia and adjust the overall gain settings using the dip switches. If the gain is too high on the Wadia, that can also create some background noise. |
If the issue is related to driving the REF 150 SE instead of balanced, perhaps one of the early Audio Research single ended to balanced converters would solve the problem? |
If I've followed all of this correctly, you've perceived the problem with two different speakers, two different tube amps, two different preamps (one of them being a phono stage used as a preamp), two different sources (one vinyl, one CD), and a variety of different cables. If so, it seems to me that there are likely to be two different problems that have been present, which are causing somewhat similar symptoms. I also tried listening closely to the speakers and found that the distortion appears almost on all frequency including bass while cranking up the volume. I would infer from this that the distortion at low frequencies is more subtle than the distortion you described earlier which was evident mainly on high volume high frequency content. And my guess is that the distortion that is evident at low frequencies is the result of amplifier clipping, while the other problem (evident especially on female vocals and piano) is due to something else. At this point I'm as mystified as you are as to what the "something else" may be. What may be an important point regarding the possibility of clipping the amp: Depending on how the Ref 150 is designed, by providing it with a single-ended signal you MIGHT in effect be using only one-half of its balanced signal path, which would reduce its 150 watt power capability to possibly as little as 1/4 of that amount (37.5 watts). I'd suggest contacting ARC and asking them if providing the amp with a single-ended signal would affect its power capability, or have other adverse consequences. If that turns out to be an issue, converting single-ended to balanced with a suitably chosen transformer from Jensen Transformers or (at a higher price point) SMc Audio (Steve McCormack) would be a solution. Mofi, thanks very much for the nice words. Coming from someone with your extremely extensive experience, that's a meaningful compliment indeed. Best regards, -- Al |
If both KEF and Maggie suffer the same distortion from the Ref 150, and no sign of anomalies from other components, is it possible that I've purchased a defected Ref 150? Or simply because the Ref 150 did not match the Maggie perfectly? I think you narrowed it to the Ref 150. This problem has nothing to do with a "mismatch" with a speaker, when your Phono Input is ok and based on your own comparisons, the Ref 150 has a defect part inside. |
BTW, I do agree that my system sounds more linear and faithful to the source by connecting the 4 ohms tap directly to the Maggie.
Thinking about the beginning when I first bought the Ref 150, it was used to drive my previous KEF 201/2 speakers and from that time on I started to experienced distortion on certain recording. Only not as severe as with the Maggie. Perhaps the Maggie's higher resolution and the recently purchased XV-1S which replaced the XX2 has made the issue worst.
If both KEF and Maggie suffer the same distortion from the Ref 150, and no sign of anomalies from other components, is it possible that I've purchased a defected Ref 150? Or simply because the Ref 150 did not match the Maggie perfectly? |
Thanks for valuable input from all!
Yes, trouble shooting procedures which I've been carried out also includes bypassing the SUT and CAT SL1 in the system, by using a EAR 834P phono preamp that comes with volume control and MM/MC function connected directly between the tonearm and Ref 150. Same thing happens! So I assumed there is no issue with overloading from the SUT and preamp.
Last night I did a final test by listening again to digital sources from a Wadia 381i CD player connected to line stage of the CAT SL1. To my surprise, the same distortion also happens on the digital source which I thought didn't exist! I'm not a big fan of digital hence very seldom listen to it. The last time I listened to it were kind of background listening with lower volume. This time I crank up the volume control to about the same level while listening to LPs and the same distortion shows off immediately!
In the mean time, I also tried listening closely to the speakers and found that the distortion appears almost on all frequency including bass while cranking up the volume.
With these latest discovery I began to suspect that the true problem might be coming form either the Ref 150 or the Maggies.
Any thought?
Thanks again! |
Sorry that I was lazy in my response above. I should have
stated what Al, (as usual, very highly detailed and correct.
We are really lucky to have Al on here. Yeah, I'm a fanboy)
did about the gain(s).
I did look up all the gain stages, but didn't really get
into it before. If you have 26 + 26 + 47 that's 99db of
gain which is WAY TOO HIGH! That really leads me to
determine that the distortion is coming from overloading. I
can almost guarantee that's your problem.
Try taking out the SUT and see what happens. |
Pakwong, using zeros will not help, and could possibly hurt. Tube amps like the ARC Ref 150 work best if the speakers impedance is perfectly flat as a function of frequency response.
Take a look at John Atkinson's bench test results of the Ref 150 and look at his measurements of output power and distortion as a function of speaker impedance. The amp's ability to produce clean power is attenuated if the load impedance deviates from the amp's nominal impedance at the relevant output tap.
This is not a big issue because as Al (Almarg) recently remarked, a rough rule of thumb is that an amp's power output demand is roughly 50/50 at the 300 Hz frequency. Stated differently, one would do better to match the speaker impedance in the low bass/midrange frequencies to the amp's nominal impedance at the relevant output tap.
An example might help. If your Maggies present a flat 4 ohm impedance load as a function of frequency response, then I surmise that the Ref 150 will deliver close to its rated 150 wpc channel with the least distortion ... if the 4 ohm taps are used. By contrast, if the Maggies impedance is between 3 and 5 ohms between 20 Hz and 500 Hz power region, then rises to 8 ohms thereafter, I surmise that the Ref will still do a pretty good job delivering clean power into that load if the 4 ohm taps are used.
OTOH, if the Maggies impedance is between 3 and 5 ohms between 20 Hz and 500 Hz, then rises to 8 and 15 ohms thereafter, I surmise that the Ref ability to deliver clean power may be a tad attenuated if the 8 ohm taps are used. The reason is the amp is being asked to drive a low impedance load in the power range when speaker and amp impedance is not well matched.
Hope this helps. In the end, most tubies like me say, go with what sounds best. Nevertheless, I am a little concerned as to whether the Ref 150 can bring out the best in the Maggies. |
"It so happens that I have some AQ Columbia ICs with DBS but it just didn't work after I tried them this afternoon. I also tried with different taps with and without the autoformer and it didn't work either."
Is your Columbia balanced or single ended? I know I said to try both if you can, but a balanced cable with an adapter for the preamp connection will most likely be the fix (if the problem is actually cable related.). |
I think, you overload your phonsection. Distortion has nothing to do with Antiskate, Azimuth or wrong alignment when you only can hear it in the upper frequencies when the dynamics start to rise. "This" kind of distortion in Phono is normally the result when the SUT is too strong( or the cartridge is too strong for the SUT, you can see it this ways or the other way). 0.3mV MC run normally easy with 60-63dB, sometimes a bit more but not much. Try to loan a SUT with 10dB less, just for a check or when one of your friends owns a cartridge with 0.20mV, try to loan it. Next is the output power from your Preamp to your power amp. When the Pre drives the amp easily, this kind of distortion becomes much more present even at lower volume. |
I agree with many of the others that the likeliest cause of the problem is related to cartridge installation and adjustment, including VTF. One thing that hasn't been mentioned is anti-skating. Take a look at the cartridge from the front, while a record is playing, and see if the cantilever is pointed approximately straight ahead, or more precisely, that it is at the same angle as when it is lifted off of the record. If there is a significant deflection of the cantilever to the right or the left while the stylus is in the groove of a rotating record, relative to its rest position, it means (IMO, at least) that anti-skating is significantly misadjusted. However if further work with the cartridge-related adjustments does not resolve the problem, overloading, as mentioned by others, is also a strong possibility IMO. I say that despite the fact that the SL1 appears to have unusually good overload margin. 08-11-14: Pakwong
Answer to Jfrech:
"Do you have the Bob's devices SUT into the MC or the MM input on your CAT pre?"
CAT SL1 Ultimate MK2's phono stage are thought to be MM only. Is doesn't comes with MM/MC switch. According to the specs shown here for your particular version of the SL1, its phono stage gain is 47 db. The lowest gain setting of your SUT (which I assume is the setting you are using) is 26 db. The line section of the preamp will add up to another 26 db depending on the setting of the volume control. That all seems very high even for a cartridge rated at 0.3 mv. So an experiment that would seem to be very much in order would be to see if the distortion still occurs with the SUT removed from the system, even if that results in unacceptable noise levels. Susceptibility to overload will be further increased (especially when high frequency energy is present at high amplitudes, consistent with your description of the problem) if the cable between your SUT and the preamp is long and/or has high capacitance per unit length. The capacitance of that cable, as seen by the cartridge, will be multiplied (not divided) by the square of the voltage step-up ratio of the SUT. In other words, by 400 times (for the 26 db gain setting). That will raise the amplitude and lower the frequency of the ultrasonic resonant peak in frequency response formed by the interaction of the inductance of the cartridge and the capacitance it is loaded with. In addition to keeping the cable length between SUT and preamp short, you might try putting a load resistor across either the input or the output of the SUT. I see that the recommended load resistance for your cartridge is specified as ">30 ohms," while the 26 db gain setting of your SUT together with the 47K input impedance of the preamp will result in a load of 118 ohms. You might try something like 50 to 100 ohms across the primary (input) side of the SUT, or 20K to 40K across the secondary (output) side. One final point: You mentioned that the problem remained when you tried a single-ended tube amp. If that amp provided an XLR input even though its internal signal path is unbalanced, and if you connected the preamp to that amp with the same RCA-to-XLR cable used with your ARC amp, the cable is not ruled out as a suspect. If the unused signal pin on the cable's XLR connector (generally pin 3, although possibly pin 2 in some countries) is not grounded (i.e., connected to pin 1), it could account for the problem. Proper connections within the cable can be easily verified with a multimeter. Hope that helps. Regards, -- Al |
Answer to Alan:
"Try increasing the tracking force to the maximum recommended for your cartridge."
Another good suggestion. Will try out. |
Answer to Skinzy:
"I once had a similar problem and it was cart alignment issue as several others have suggested."
Although I have done this many time but I will surely do it all over again as suggested by Wlutke. |
Answer to Wlutke:
You have described the distortion problem I have been working on for some time now, although yours sounds more severe. Mine was with high pitched, high amplitude vocal "air", mostly female, but piano was ok. I have the DV XX2 MK2 and also use the Mint tractor. The problem turned out to be the distance from the spindle to the tonearm pivot was off a little. A very tiny little. Because of that the Mint Tractor made me align, very precisely, to the wrong arc and overhang. I used the VPI jig that came with the arm to reset the distance. After realigning the cart with the Mint the distortion was eliminated and replaced by incredible detail. Double wow! I had tried everything I could think of for months on end. The DV carts have a well deserved reputation of being sensitive to setup error. Good luck!
This is something I never think of. Well worth a try. |
Answer to Zd542:
"Try that first. Use any CD/DVD player you can find. It doesn't have to be expensive. If that doesn't work, I would try a different pair of IC's between your amp and preamp. I don't think you can switch your amp to run in SE or Balanced operation. I think it just runs in Balanced. I've seen several times where you can get a noise because of it. The solution, in the cases I've seen at least, was to use a good quality shielded IC. Any Audioquest with the DBS system always worked (providing that was the problem). Most ARC dealers have AQ. See if they will lend you a balanced and a SE IC to try in your system. You'll also need 2 adapters. If your dealer doesn't have them, you can get them at any music store. You need male xlr/male rca adapters for the balanced cable and male xlr/female rca adapters for the SE cable.
You've probably already did this, but you may want to try some different taps on you amp, both with and without the autoformer. "
It so happens that I have some AQ Columbia ICs with DBS but it just didn't work after I tried them this afternoon. I also tried with different taps with and without the autoformer and it didn't work either. |
Answer to Bifwynne:
"Although I am not speaking to whether the rest of you rig has issues, I have serious doubts that the Ref 150 has enough power to properly drive the Maggie 3.7s. The consequence of over-driving the amp is ... distortion. "
"Btw, if the Maggie's have a nominal impedance of 4 ohms, especially in the bass/lower midrange frequency spectrum, I suggest trying the 4 ohms taps. "
I do speculate perhaps Ref 150 not powerful enough to drive the Maggie properly. Remember I said Maggie dealer used a transistor amp to test and it sounded okay without distortion? That Class D Esoteric can output 400 watts into 4 ohms. So probably power is the issue.
Btw, before adding the Zeros, I run Maggie with 4 ohms tap with the same distortion. |
Answer to Mofimadness:
"From what you describe, I think that maybe you are overloading the phono input. Make sure you are using the MM input and not the MC. If you are using the MC along with the SUT, it could very well indeed be too much gain."
Please refer to my answer to Jfrech. |
Answer to Lack:
"I own a pair of Maggie 3.7's but I run them with a SS amp.
I have no idea what the problem is but was just wondering if you ever tried using the resistors with the Maggies and if that would correct any of your issues?"
Tried that. Nothing change. |
Answer to Smoffatt:
"Can you borrow a digital source (CD player) and play the same recording to see if you can identify the same distortion as with your analog source. If no apparent distortion, the problem may be with your tonearm/cartridge alignment.
Somewhat odd that only some recordings and/or passages of same are sound distorted. Could very well be your SUT or cartridge or alignment."
I do have a CD player but don't have CD version of distorted recordings on LP as my CD collection was very limited. It's definitely not the SUT. I bypassed the SUT and the CAT preamp by connected phono cable of tonearm directly to a phono preamp with volume control and feed the signal directly to Ref 150 with the same distortion. |
Answer to Brownsfan: "There are plenty of people that drive Maggies with tube amps. I agree that tube microphonics would explain what you are hearing, and it is pretty easy to address. Also, the fact that you tried two other speakers, one of which gave you the same result, probably means it is not the Maggies per se. However, because they are dipoles, they may direct more energy back to the tubes. Just wondering, the other speakers you tried--- were they both rear ported? If the one that didn't give you distortion is front or bottom ported, or sealed, that could also be a clue."
Please refer to my answer to mrderrick about tubes's microphonic. Both pair of speakers I used for testing were box speakers. One pair was KEF Ref 201/2 which has the same distortion while the other Focus Audio FC9 pairs sounded okay. The KEF is upright ported while the FC is back ported at medium height. Any clue?
I did swapped ICs and speaker cables but nothing change. |
Answer to Jfrech:
"Do you have the Bob's devices SUT into the MC or the MM input on your CAT pre?"
CAT SL1 Ultimate MK2's phono stage are thought to be MM only. Is doesn't comes with MM/MC switch. |
Answer to Mrderrick:
"You tried a second tube amp and still had the same issue.
I would try all of the output taps on the Ref150 and see if there is a difference. ( without the auto formers first )
I would then try the auto formers with the best performing tap if you still need them.
My experience is that Maggies need to be driven at moderate levels at the very least to sound best."
In my case I do agree the Maggies need to be driven at moderate levels to sound best as the distortion were less obvious or even disappeared with lower volume. Perhaps I need a more powerful amp but this would be my last resources to solve this. In the mean time I will try all output taps to hear the difference. No harm trying! |
My appreciation to everyone for their serious advices.
Answer to Lloydedee21:
"Is it possible the tubes are slightly microphonic, and your speakers are picking it up? Have you tried tube dampers? Borrow some if you can before going out and buying. Sometimes when a tube is microphonic it will pick up certain noises either internal to the tube due to vibration or due to vibration in the room outside the tube...and translate it as distortion thru the systems signal."
I do have dampers from Herbie's Audio Lab on all tubes so I assume no issue with microphonic effect. |
Try increasing the tracking force to the maximum recommended for your cartridge
Alan |
I once had a similar problem and it was cart alignment issue as several others have suggested. |
"08-10-14: Smoffatt
Can you borrow a digital source (CD player) and play the same recording to see if you can identify the same distortion as with your analog source. If no apparent distortion, the problem may be with your tonearm/cartridge alignment.
Somewhat odd that only some recordings and/or passages of same are sound distorted. Could very well be your SUT or cartridge or alignment."
Try that first. Use any CD/DVD player you can find. It doesn't have to be expensive. If that doesn't work, I would try a different pair of IC's between your amp and preamp. I don't think you can switch your amp to run in SE or Balanced operation. I think it just runs in Balanced. I've seen several times where you can get a noise because of it. The solution, in the cases I've seen at least, was to use a good quality shielded IC. Any Audioquest with the DBS system always worked (providing that was the problem). Most ARC dealers have AQ. See if they will lend you a balanced and a SE IC to try in your system. You'll also need 2 adapters. If your dealer doesn't have them, you can get them at any music store. You need male xlr/male rca adapters for the balanced cable and male xlr/female rca adapters for the SE cable.
You've probably already did this, but you may want to try some different taps on you amp, both with and without the autoformer. Now that I think about it, is it OK to use the autoformer with an amp that already has an output transformer? Hopefully, someone that knows will comment on that. I'm not sure. |
As an fellow owner of an ARC Ref 150, I have a sense of what your Ref 150 can do. You cam confirm what I am advising with Kal at Audio Research.
Although I am not speaking to whether the rest of you rig has issues, I have serious doubts that the Ref 150 has enough power to properly drive the Maggie 3.7s. The consequence of over-driving the amp is ... distortion.
Btw, if the Maggie's have a nominal impedance of 4 ohms, especially in the bass/lower midrange frequency spectrum, I suggest trying the 4 ohms taps. While many tout the virtues of the Zeros, to me, they are just another artifact.
The Ref 150 is designed to produce clean power up to its rated spec (150 wpc) if the speaker's impedance (4 ohms) matches the amp's output impedance off the 4 ohm tap ... at least if tasked to produce in the power spectrum (bass/midrange). Impedance matching is less critical at higher frequencies because power demands are less.
Btw, btw, output voltage regulation is tighter off the 4 ohms taps. As a consequence, if the Maggie's impedance function rises in the mid/tweeter range, using the 4 ohm taps will result in the Maggies sounding less bright.
Let us know how you make out.
BIF |
I agree on the overloading. If its louder musical peaks, its a higher output voltage at those peaks and its just about exceeding somethings limit. |
From what you describe, I think that maybe you are overloading the phono input. Make sure you are using the MM input and not the MC. If you are using the MC along with the SUT, it could very well indeed be too much gain. |
You have described the distortion problem I have been working on for some time now, although yours sounds more severe. Mine was with high pitched, high amplitude vocal "air", mostly female, but piano was ok. I have the DV XX2 MK2 and also use the Mint tractor. The problem turned out to be the distance from the spindle to the tonearm pivot was off a little. A very tiny little. Because of that the Mint Tractor made me align, very precisely, to the wrong arc and overhang. I used the VPI jig that came with the arm to reset the distance. After realigning the cart with the Mint the distortion was eliminated and replaced by incredible detail. Double wow! I had tried everything I could think of for months on end. The DV carts have a well deserved reputation of being sensitive to setup error. Good luck!
Bill |
I own a pair of Maggie 3.7's but I run them with a SS amp.
I have no idea what the problem is but was just wondering if you ever tried using the resistors with the Maggies and if that would correct any of your issues? |
Can you borrow a digital source (CD player) and play the same recording to see if you can identify the same distortion as with your analog source. If no apparent distortion, the problem may be with your tonearm/cartridge alignment.
Somewhat odd that only some recordings and/or passages of same are sound distorted. Could very well be your SUT or cartridge or alignment.
Good luck!! |
There are plenty of people that drive Maggies with tube amps. I agree that tube microphonics would explain what you are hearing, and it is pretty easy to address. Also, the fact that you tried two other speakers, one of which gave you the same result, probably means it is not the Maggies per se. However, because they are dipoles, they may direct more energy back to the tubes. Just wondering, the other speakers you tried--- were they both rear ported? If the one that didn't give you distortion is front or bottom ported, or sealed, that could also be a clue.
On the other hand, I had no such problem with my 3.7s with my Coincident Line stage preamp, which uses highly microphonic 101D tubes, and had no problems, although I do use tube dampeners.
It might also be worth switching out the speaker wires and ICs if you have spares. A weak connection at the terminal can give intermittent distortion problems. |
Do you have the Bob's devices SUT into the MC or the MM input on your CAT pre? |
I suspect that your problem lies with your amplifier.
If I recall correctly, the Maggies prior to the ".7's" had rather ruler flat impedance curves.
The crossovers have changed and this is no longer the case.
I owned MGII B's, 3.6's and still have a pair of early MMG's.
The MGII B's (6 ohm load ) could be driven with a 40 watt PP tube amp quite nicely and sounded beautiful, at low to moderate levels.
The 3.6's I drove with a Classe CA400 SS amp which pumped out 800 watts into a 4 ohm load.
You tried a second tube amp and still had the same issue.
I would try all of the output taps on the Ref150 and see if there is a difference. ( without the auto formers first )
I would then try the auto formers with the best performing tap if you still need them.
My experience is that Maggies need to be driven at moderate levels at the very least to sound best.
More power was always better for me with Maggies.
The Ref 150s may not be up to the task, even with the auto formers.
If you have not visited the Planar Forum at the Audio Asylum, you should and ask for assistance there. |
Hmmmm, I am no techie. But when you get a problem at only presents itself during certain passages of music...it seems less like an electric problem (which you would think would occur all the time or at least randomly)...and more like a mechanical problem. Something reacting to those treble frequencies or something?
Is it possible the tubes are slightly microphonic, and your speakers are picking it up? Have you tried tube dampers? Borrow some if you can before going out and buying. Sometimes when a tube is microphonic it will pick up certain noises either internal to the tube due to vibration or due to vibration in the room outside the tube...and translate it as distortion thru the systems signal.
I once had a tube so microphonic if I clapped or whistled you could hear it thru my speakers. A tube damper from EAT solved it...and so did replacing the tube! Again, I am no techie, just a thought. Good luck. |
