Distortion with ARC Ref 150 and Maggie 3.7

"All I get from the town is water and they are billing me $10,000+ for property tax and RISING. Can you say Detroit!"

And the water is probably not very good. I think you should consider drilling your own well and get rid of the town altogether.

10-20-14: Zd542
"If your house has no access to natural gas, would you buy a natural gas furnace? Post purchase, install propane and all the hassles in getting it to work."

A lot of people do it that way. Not only that, you can usually make a deal with the gas company. They'll give you the gas furnace for free, along with the install, as long as you buy the gas from them.

Yes if you switch to natural gas. There's no natural gas line in my area so I have to use propane and no company is going to replace my oil furnace for free. I'll switch to propane in next MAJOR renovation.

Now I have ARC Ref250 for the winter, it should lower my oil bill. LOL!

All I get from the town is water and they are billing me $10,000+ for property tax and RISING. Can you say Detroit!

"If your house has no access to natural gas, would you buy a natural gas furnace? Post purchase, install propane and all the hassles in getting it to work."

A lot of people do it that way. Not only that, you can usually make a deal with the gas company. They'll give you the gas furnace for free, along with the install, as long as you buy the gas from them.

Thanks Knghifi for the reminder.

Received the resistor from Audio Research and sent out the ARC 150 for trouble shooting this afternoon. Wish my technician would find out the problem with start circuit soon. In the mean time my listening room is under renovation so it's about right timing.

Regards,

**Most of the time** you can expect an amplifier with a balanced input to work just fine with a single-ended source.

However, balanced line and single-ended operation are not normally considered to be compatible (by the pro audio industry). As a result, you usually have to jump through some hoops to make the two work together. In our equipment, that means joining pin 3 to pin 1 on the XLR and its all good. With the ARC amplifiers, the *only* way to do it is to use a transformer; Jensen makes some of the best transformers world-wide for this application.

10-10-14: Bifwynne
Knghifi ... your comment applies not just to amp/preamp combos but to other system components as well, such as speaker and tube amp matches.

Not just to other system components as well but to everything in life.

If your house has no access to natural gas, would you buy a natural gas furnace? Post purchase, install propane and all the hassles in getting it to work.

Just common sense.

This is no knock on Pakwong and he has learned his lesson. Sometimes we all have to learn the hard and expensive way. Like the time I was the general contractor building my house with no prior experience. Bought the land ... cost me BIG $$ but very valuable lessons.

Knghifi ... your comment applies not just to amp/preamp combos but to other system components as well, such as speaker and tube amp matches.

Believe me, just read some of my posts where Al (Almarg) and Ralph (Atmasphere) had to walk me through electrical compatibility issues involving my Ref 150 tube amp and my Paradigm Sig 8s (v3). The issue being electrical consequences of matching my tube amp's somewhat high'ish output impedance and the rock and roll impedance and phase angle plots of my S8s.

I'm ok now ... but only after lots of on line conversations with Al and Ralph, off-line learning, and ultimately putting together a combo that makes a lot of sense in terms of integrating my Ref 150 amp, my speakers, my self-powered sub woofer via a new gizmo I just bought ... the DEQX PreMate.

Almarg, until Minorl post, I felt tone of the thread was blaming and questioning ARC design which was unfair IMO.

So I want to make a GENERAL SUGGESTION best do pre-purchase homework to avoid compatibility issues post purchase so I guess it applies to both Pakwong ARC and CAT experiences.

Thanks for the update, Pakwong. Sounds like a good plan, which will greatly reduce the risk I had been envisioning if the CAT doesn't work out.

BTW, although I could be wrong, I had been interpreting Knghifi's comment about doing homework before purchasing to be in reference to the CAT purchase, not to the ARC purchase. As you said, it's very unusual for a balanced amp to not be able to work in a reasonable manner when provided with an unbalanced input, so that "oversight" is certainly understandable. And since you have a fallback strategy which minimizes the risk I and perhaps he were envisioning regarding the CAT purchase, it seems like all the bases are covered (to use a baseball analogy).

Continued good luck as you proceed. Regards,
-- Al

I admit that I didn't do enough research before buying a balanced only amp for my single ended only preamp. So I'm the one that should be blame. However, it's a rare case when an adapter cable couldn't solve the connection problem. Anyway, I hope the negative comments on ARC shall end now.

Al, I didn't have the chance to audition the JL5 with my system. But I have friend whom I can trust to build confidence on the CAT amp. I only have moderate size room(10'x14x'17') and didn't go for high SPL while listening, so I think the 100 watts JL5 is good enough. I'll still keep the Ref 150 for comparison. If the Ref 150 is superior to the JL5, I don't worry about selling it as I bought with good price and there are plenty of CAT's fan down here. Perhaps I have same "problem" as Bifwynne, just don't feel comfortable with something else in the signal path!

Best regards,
Pakwong

Almarg, we will have to disagree about how appropriate, or more importantly, how helpful someone's recent comments on this thread have been. So many people have offered advice and guidance trying to solve the OP's situation. I didn't see the point of chiding or berating him. When I did the same thing to that poster, not surprisingly he didn't like it. Was what I did petty? Borderline. However,

This is an open forum and I'm contributing my .02.

Thanks Al. I take your point about using a transformer to connect an SE output to an XLR input. As I have admitted many times, I am not a EE-type, so the theory and application is way north of my pay grade. I suppose I am just biased (pun) about inserting artifacts into the signal path.

You may properly ask why, if I really feel that way, did I insert a DEQX digital time and EQ correction device in between my linestage and amp? My response: perceived sonic cost versus perceived sonic benefit. So far, I believe the latter significantly outweighs the former, ... I hope and think?????

Thanks for the electronics lesson. :)

Bruce (Bifwynne), I wouldn't consider the use of a Jensen transformer to be a jury rig/jerry rig/kludge (whichever terminology one prefers). It's a legitimate means of converting a single-ended signal to a true balanced signal pair.

Consider also that some extremely highly regarded preamps have transformer-coupled outputs, and in some cases also utilize transformer coupling in their internal signal paths. Examples include the Coincident Statement line stage, and some ultra-expensive Audio Note models.

Of course, all transformers are not created equal. But the Jensen transformers are well regarded, and as I've indicated multiple times in this thread, a number of highly experienced members here who have very high quality systems have reported excellent results with it. And the OP was quite happy with the results he was getting with it, until an unrelated problem he experienced caused the thread to be resurrected, and various subsequent responses unrelated to that problem caused him to become concerned about theoretical issues that may or may not be subjectively significant, or even perceptible, in his system.

Regarding your other comment, I don't doubt that for some and perhaps many listeners the Ref 150's power capability may be marginal with the Maggie 3.7, and in fact that very issue is being discussed in another current thread you are participating in. Of course, the degree to which that may be a concern will depend on the particular listener's preferred volume levels, on the dynamic range of the recordings that are listened to (well recorded minimally compressed classical symphonic music perhaps being the worst case), and on listening distance and room size.

My impression, however (derived in part from your comments in other threads), is that the power supply of the Ref 150 is robustly designed, including large amounts of energy storage. Which, together with your comments about its marginality with the particular speakers, reinforces the concern I expressed in my previous post about the adequacy of the lower power rating (100 watts) of the CAT JL5.

Onhwy61, I'm surprised at your response to what I thought was a knowledgeable and entirely appropriate input from Knghifi. I would especially not have expected such a response from you in particular.

Best regards,
-- Al

Just read the last 5 or 6 posts. I posted a few comments a while back. Two points.

First -- Yes ... it is true. The ARC Ref 150, and presumably Ref 250, are designed to accept only a balanced (XLR) inputs. Not an SE (RCA) type. If you can rig some contraption to somehow do an end-run ... all the power to you. I own an ARC Ref 150. The last thought that would come to my mind would be to jury-rig (sp?) that type (or any type) of similar gizmo.

Second -- I've said this before and I'll repeat it once again. Maggies are power hogs.

I think Maggie 3.7s deserve a lot more juice than the Ref 150 can deliver. I'm sure the Ref 150 can drive the Maggies to an "ok" SPL, but not to the point where the 3.7s will open up and sound their best. I seem to recall that many years back, I had a similar conversation with either Len or Kal at ARC. They expressed similar views.

10-04-14: Onhwy61
In a free society a person should be able to do his homework whenever he wants to and it's nobody's business but his own.

Are you serious? You have issues with my suggestion?

I could care less what Pakwong does with his $$ and problems. This is an open forum and I'm contributing my .02.

As others have pointed out, it's questionable why ARC makes amplifiers that cannot operate correctly with single-ended sources.

Because it wants to?? In a free society a company should be able to produce whatever it wants. They stay in business if there are demands, otherwise bye bye.

Also in a free society a person can buy whatever they want. If they don't like ARC's approach, don't buy it. Again, if you do your homework pre-purchase, it will save some headaches.

In a free society a person should be able to do his homework whenever he wants to and it's nobody's business but his own.

As others have pointed out, it's questionable why ARC makes amplifiers that cannot operate correctly with single-ended sources.

10-04-14: Pakwong
The fact is, though having trouble with the Ref 150, I'd still recognized it as a great amp after solving the matching problem with the CAT preamp. But as recommended by some of you here, I feels that the Ref 150 would be better matched with a true balanced preamp as the design concept suggested, in order to achieve the amp's full potential. If the new ARC preamp has build in phono stage like the good old days, I would have gone the ARC path!

You should do your homework before and NOT after the purchase.

CAT makes great amps so you will be happy but it doesn't sound like ARC. They are different and not superior to the other. GL!

The fact is, though having trouble with the Ref 150, I'd still recognized it as a great amp after solving the matching problem with the CAT preamp. But as recommended by some of you here, I feels that the Ref 150 would be better matched with a true balanced preamp as the design concept suggested, in order to achieve the amp's full potential. If the new ARC preamp has build in phono stage like the good old days, I would have gone the ARC path!

Regards,

Zd542, Thank you for your retraction. All good.

"10-01-14: Daveyf
So Zd542, you want to expand on why you believe what i posted is incorrect.
I am all ears."

No. It was my post that was incorrect. My post was meant as a humorous comment for someone else in an entirely different thread. How I managed to put it here, I have no idea. Sometimes I'm amazed that I don't kill myself just getting out of bed in the morning. Sorry.

As might be inferred from this post I made two days ago, I am in essential agreement with Minorl's comments. And especially with:

My reading of the posts, indicates that the OP used the Jensen transformer and the resulting sound is wonderful. Problem solved.

The old saying "if it ain't broke, don't fix it" comes to mind. (In this case, of course, the amp is broken and in need of repair, but that is unrelated to the question of whether or not to replace it). Certainly the JL5 will be a good match with Pakwong's preamp. But can anyone say with a high degree of confidence that it will be a better sonic match for the Maggie 3.7 speakers than the combination of the ARC amp and the Jensen transformer? Or that its 100 watt power capability will be adequate, considering that a VTL amp rated at 50W triode mode/100W tetrode mode into 5 ohms is not?

Pakwong, hopefully you can audition the JL5 in your system prior to committing to a purchase. Otherwise, it seems to me that you would be bringing significant risks into play, in an effort to eliminate what may be from a subjective standpoint (as opposed to a theoretical standpoint) a non-issue.

Good luck. Regards,
-- Al

Minorl +1

I don't think the attacks on Audio Research are warranted.
My understanding of this conversation is that the OP used an RCA to XLR conversion cable and even Audio Research would tell him that that type of cable should not be used. The Audio Research equipment when used as directed is wonderful. As with any equipment, if you connect it in opposition to the way the manufacturer recommends, then it won't work correctly. The solution was simple after conversations with AR and other experts. 1) use a transformer set up like Jensen, 2) replace the AR amp with an amp that handles RCA only or 3) replace the pre-amp with a balanced pre-amp. My reading of the posts, indicates that the OP used the Jensen transformer and the resulting sound is wonderful. Problem solved. I'm not really defending AR, but the direction the posts were going were a direct attack on a company that really didn't do anything wrong and produces absolutely wonderful equipment. And since I can't think of one manufacturer that hasn't produced equipment that eventually failed or required upgrades or repairs, it is unfair to label this was as problematic. The way AR designs their products is the way AR designs their products. Same is true for all other manufacturers. They chose a design path and that is the way they went. I for one really like their equipment and if the funds were there would jump on the opportunity to own them. REF 5SE, REF 250 amps, oh yeah! I can say the same for many other manufacturers out there also. AR produces top-of-the-line products, but like all others, you have to use them per the manufacturer's recommendations.

Sorry for the long rant, but enough already with the AR bashing. In this case, it is totally unwarranted.

enjoy

Ralph, that would seem to have been a smart thing to do. Pity other companies failed to see or take that path.

Agreed! Our amps are also fully balanced and differential; we made sure that it was no worries or loss of performance to use them with a single-ended preamp or source.

Atmasphere, totally agree with your statement.

I would suggest all balanced amp should be more user friendly so people who has live with unbalanced equipment for a very long time could try their hand on balanced equipment which they are not familiar with and eventually discover the benefit balanced amps has to offer.

Pakwong, Congrats on the JL5. I think it will put the ARC to shame.Great amp and a perfect match for the CAT preamp.

Pakwong, I would not take this particular event as somehow being a problem with balanced operation. I've been working with balanced line equipment for decades; this sort of problem that you experienced says more about Audio Research than anything to do with balanced operation.

We've been building balanced line equipment for high end audio longer than anyone else- all I can tell you is this should not have been a problem and is something unique to ARC.

Thanks all for good opinions and comments.

At the moment I'm still waiting for ARC to send me the resistor as my technician down here couldn't find resistor with such value. In the mean time, my ever faithful VTL MB125 monoblock continue to serve music with the CAT. They are both single ended so no distortion issue here. The sound with the Maggie is acceptable but there were some sort of distortion at higher volume/peak of music probably due to lack of driving power.

After having such bad experiences with the balance amp, I think it's better to stick to single ended. Moreover, my CAT has comes with decent phono stage so changing the power amp instead of the preamp might save me some money. While me and some of my audiophile friends has got very good offer from local CAT dealer, I've decided to grab a new Black Path JL 5 to end the misery!^^

Anyway, will keep you guys posted on the ARC issue.

Thanks again!

So Zd542, you want to expand on why you believe what i posted is incorrect.
I am all ears.

Yes Almarg, that was what I was trying to clarify in my post. Most people don't consider the preamp to be the "source".

Atmasphere, I have had the same conversation with Kalvin. He told me also that the preamp must be balanced with the Ref150. He did not use the word source, just preamp.

"10-01-14: Daveyf
Ralph, IMO the loss potential generated by the additional electronics needed to go balanced in home electronics; is more of a problem than what one typically sees as noise infiltration into the system by outside sources. Unlike in the pro audio world, in home hi-fi, we're talking of cable runs of what...a few meters at most. In pro audio it may be 50-60'++ , then i can see the potential benefit. A cable that is effected by noise that is 6" in length must be a ****poor cable IMHO."

I can't help but think of that old saying "You know enough Karate to get your ass kicked.", when I read that post.

BTW, both Dick Olsher and Jonathan Valin wrote reviews of the Carver amps and basically said that the Carvers were excellent matches for the Maggies. Read this:

http://www.enjoythemusic.com/superioraudio/equipment/0512/bob_carver_cherry_180_tube_monoblock_amplifier.htm

http://www.theabsolutesound.com/articles/carver-black-beauty-305-power-amplifier/

Guys, I read this entire thread and got lost a couple of times but here is my thought. The Ref 150 is NOT a good amp for any of the Maggies. Sell the 150 and try a pair of Carver Cherry 180's or even better a pair of his Black Beauty 305's. The Black Beauty's use six KT-120's per side and can drive anything. They sound fantastic on my 20.7's and I have tried many different amps.

^^ This.

Ralph & Dbarger, you appear to be disagreeing simply because you are using the term "source" to mean different things. I believe that Ralph is referring to the "source" of the signals which are sent into the power amp, e.g., a preamp. Dbarger is referring to the "source component," e.g., a CD player.

As Dbarger appears to indicate, I would not expect there to be any problem if the power amp were driven by a balanced output of a preamp which in turn receives a single-ended input. Assuming, that is, that the preamp's output truly consists of a balanced pair of signals, rather than a single-ended signal provided on an XLR connector.

Regards,
-- Al

Daveyf, anytime you put current through the shield of the cable, you are subject to the construction issues of that cable. So this is a big issue with single-ended, even if its only 6 inches. In a balanced system (caveat: if the balanced standard is being properly supported...) the shield sees no signal current at all.

FWIW there does not have to be any 'loss potential' caused the additional circuity when going balanced (a common myth is that there is twice as much circuitry, which is not true, especially if the circuit is fully differential). For example, a fully differential circuit can have up to 6 db less noise per stage of gain as opposed to the same topology running single-ended. So in two stages of gain you could have up to 12db less noise! This has real benefits in preamps working with low output moving coil (which is a balanced source BTW), as you might only need two stages of gain for a functional tube phono section! That is **less** stages for the signal to go through than single ended.

In our amps because of this we only have one stage of gain. So you can actually have a simpler signal path than an SET might have.

On top of that, balanced operation in the preamp or amp means that the unit is more impervious to noise that gets into the power supply. So the potential is for lower noise and not from just the cables.

Dbarger, I spoke to both Kalvin and Warren at ARC and they told me the same thing: if the amp is used with a single-ended source it will have lower output power and will make distortion.

This is because the drive to the power tubes will become unbalanced. IOW, the amplifier is not compatible with single-ended sources and if one is employed, a transformer should be used to balance the input to the amp.

Ralph, IMO the loss potential generated by the additional electronics needed to go balanced in home electronics; is more of a problem than what one typically sees as noise infiltration into the system by outside sources. Unlike in the pro audio world, in home hi-fi, we're talking of cable runs of what...a few meters at most. In pro audio it may be 50-60'++ , then i can see the potential benefit. A cable that is effected by noise that is 6" in length must be a ****poor cable IMHO.

Davef, this quote is incorrect:

single ended gear sounds better than balanced gear; IMO,unless one is using their gear in a VERY highly corrupted noise environment or with VERY long runs of cable, balanced is nothing but a joke in high-end.

If you have ever heard a difference in audio interconnect cables, then you now know why balanced lines are not a joke- because they solve that problem if used properly! Further, it does not matter the length, 6 inches is easily enough to hear a difference, especially if there is a noisy environment. Further, the proper use of balanced lines and balanced operation offers lower distortion.

Tubes are often docked for having that ever-lovin 2nd harmonic, which is nice and rich sounding, but not neutral as it is distortion. That can be eliminated by employing balanced operation, resulting in more transparency and no loss of smoothness.

By running balanced lines, I can put my amps much closer to my speakers, allowing me to run shorter (thus better sounding) speaker cables, plus I can put my front end where I want it, rather than in between the speakers. The first thing I noticed in doing this was greater ability to make out vocals. It was not subtle.

Al, what I was describing in my post above is not a malfunction. The OP did have a malfunction, but it was coincidental and unrelated to the basic problem: distortion when driven by the CAT directly.

Atmasphere mentioned using only a balanced source. This I assume is only referring to the preamp. It is very possible to use single-ended sources into a balanced ARC preamp, going into a Ref150. They work great, it is only the preamp which needs to be balanced. ARC even makes a few of the single ended sources...

Gentlemen, keep in mind that the problem at hand is simply that the amp has broken down.

Also keep in mind that Pakwong was quite happy with the sound he was getting using the Jensen transformer, prior to the recent breakdown of the amp. And some other highly experienced A'goners having very high quality systems have reported in the past being similarly pleased, using the same Jensen transformer.

I have no doubt that Ralph's/Atmasphere's statements about the compromises the transformer introduces are correct, but it seems based on these anecdotal reports that the degree of those compromises is small enough that for many users it would not warrant replacement of either the amp or the preamp.

Best regards,
-- Al

I think the real problem here is as stated by several other posters...that is the incompatibility between the CAT and the ARC. I think ARC is simply trying to cater to fashion in regards to their seeming insistence on only using balanced inputs on their current gear. This fact has made me stay away from their gear and will continue to do so until they get the picture. I can see no reason why the extra electronics needed with the balanced option is at all necessary, except to add cost and to cater to as I stated earlier....'fashion'. Personally, I feel that single ended gear sounds better than balanced gear; IMO,unless one is using their gear in a VERY highly corrupted noise environment or with VERY long runs of cable, balanced is nothing but a joke in high-end.
My advice, dump the ARC Ref 150 and get a more suitable amp for the CAT...like maybe a CAT amp!

If it were me, I would only run an amp like that designed for balanced input with a well matched balanced output device feeding it, like Atmasphere suggests.

If you can establish that a proper balanced output device works as it should, I would agree with Atmasphere that that is the way to go, assuming the ARC is working as it should mated to the right input. If it does not, then there is some defect at play that would have to be addressed, but hopefully that is not the case.

As you may have surmised by this time, the ARC amplifier cannot be used with a single-ended source! If you do so, the amp **will not make anywhere near full power** and it will be distorted.

This is because the amplifier has a very poor Common Mode Rejection Ratio figure, on account of its input circuit (which apparently is differential) is not in fact very differential. IOW, IMO/IME, ARC missed a bet here.

At any rate, the only way to use this amplifier with a single-ended source such as the CAT is to use a transformer like you are doing (The Wadia worked of course because it has a balanced output).

There are several problems with this. The Jensen, while excellent, does not load the CAT ideally nor does it have the bandwidth of the CAT, so you are not hearing everything it does. However, unless you sell the CAT and get a balanced preamp, this is the only game in town.

I have to admit I am puzzled why the amplifier is designed in this fashion, but in conversations with the good people at ARC (a good number of whom I have known for decades) this is very much the case (As a manufacturer of balanced line products, we had to sort out compatibility with single-ended equipment many years ago). If I were you I would be seeking a balanced line tube preamp, but that's me: I don't like transformers. Plan B: Sell the amp and get something that works with your CAT. Both units are capable of excellent performance; its really a matter of which you like more. Good Luck- keep us informed.

It may have been covered earlier but was the rating and description of the amp on agon when you bought it consistent with your findings since? If not, it would seem to memaybe you have a case with the seller to either return or seek financial compensation for repairs.

Just a thought.

P.S: To clarify my previous comment about what is stated in the CAT manual, the adapter cable you had been using resulted in the amp being operated in exactly the same manner as what would occur if you were to do what is described in the paragraph you quoted from that manual.

Regards,
-- Al

Sorry to hear of this development, Pakwong.

However, I feel quite certain that a problem involving the AC power relay not closing within a few seconds after turn-on has nothing to do with the use of the Jensen signal transformer.

Also, the instructions you quoted from the CAT manual, while being applicable to most balanced amps, are not applicable to yours. As you had found when using the adapter cable, and as has been explained earlier in the thread, using the adapter cable (without the Jensen transformer) sacrifices approximately 75% of the amp's power capability, as well as having various sonic disadvantages.

In fact, although it is probably unlikely, and I'm not specifically familiar with the design, I wouldn't completely rule out the possibility that the amp became susceptible to this problem as a result of having frequently been driven into clipping (i.e., being required to exceed its greatly reduced power capability) when the adapter cable was being used for a prolonged period of time.

In any event, it sounds like either the relay or something in its associated circuit needs to be replaced.

Good luck. Regards,
-- Al

Updates:
About one week after using the Jensen PI-2RX, the Ref 150 fuses blow twice. The second time one of the electronic part overheated. I wrote to ARC and here what they answer:

"The overheated part is the turn-on surge resistor, R67. This is a 21.5 ohm / 25W resistor that is designed to cushion the current in-rush at cold turn-on of the REF150. The reason the resistor has overheated is there is a fault that is preventing the RY1 AC power relay from closing after about 1.5 seconds and bypassing this resistor. If the AC relay does not close, R67 will very quickly overheat, as it is not meant to be in-circuit for more than a few seconds. A schematic is attached. Have your technician troubleshoot the soft-start circuit to determine the fault. Note that in 220-240VAC models, this resistor is 21.5 ohms, not the 5 ohms shown on the schematic."

I was asking is this cause by the transformer or due to tubes problem (power tubes about to change) but ARC didn't give any answer.

In the mean time, I got a copy of CAT SL1 Ultimate manual and noticed that there was some instruction on how to connect the preamp properly to a balanced amp as follow:

"When using amplifiers with balanced inputs, the negative leg of the balanced input should be shorted to ground. This prevents hum and noise problems caused by the floating inputs. While most amplifiers with balanced inputs provide a switch for this purpose, inserting a jumper in the XLR connector will accomplish the task. Alternately, an XLR connector can be prepared with this jumper soldered internally, and the connector then inserted into the XLR jack."

If the CAT's wired method for the RCA to XLR cable really works, I think perhaps it's better to stick to the conversion interconnect cable.

Any advice?

Thanks in advance!

That was a very helpful thread and lots of very good information.