Hi guys, got the RX few days back. They work the same as the XX, no difference in sound quality as I use the same IC which changed to RCA plug at output end.
Anyway this unit need a few days to sound their best just like every other audio product. I would say the Jensen transformer has done a great job on converting unbalanced to balanced signal. My system sound like never before with no perceivable anomalies. The balanced signal has makes the Ref 150 unleashed it's full potential by creating a fantastic deep and spaciousness sound stage through Maggie 3.7. I would recommend this product to anyone with the same issue. You'll get good price from eBay.
Thanks all! |
Thanks Al, I'll wait for the PI-2RX for comparison. Will keep you posted. |
Great!
I don't doubt their statements about the RX vs. XX. And actually when I suggested the RX I hadn't thought of the possibility of using the XX with your existing adapter cable.
I'd expect that either approach will work well, and will solve the initial problem, but there may be some sonic differences resulting mainly from differences between the cables themselves. Which would be preferable, if in fact there is any difference, is probably unpredictable.
Regarding the slots and screws you asked about, I believe those are to provide the option of connecting via bare wire, which is sometimes done in pro applications. So you can ignore them.
Best regards,
-- Al |
Hi all, I finally got the Jensen transformer but they sent me the PI-2XX instead of PI-2RX which I order. When I requested for exchange, they said it's electrically identical to the PI-2RX but they were happy to exchange. Which means I could use a RCA to XLR conversions cable to achieved the same purpose. Since I'm not very sure of that and remember Almarg recommended the PI-2RX, I've placed another order for the PI-2RX just for comparison and send back one of them for refund later.
This afternoon I anxiously did a brief audition with the PI-2XX in my system with existing RCA to XLR conversion cable and a newly purchased two feet length XLR cable. Guess what? Those albums which were prone to distortion especially piano sound and vocal came out nice and clean! I also noticed significant improvement at the lower frequency.
Thanks Al and others for helping me overcome the distortion issue successfully. Now the question is, are the PI-2XX and PI-2RX actually electrically identical to each other, only differences were the XLR or RCA connector on the input side?
This Isomax device is very well build and there were some slots with screw on the other side of the device. Any idea what is that for?
The seller did mentioned that the PI-2XX were more versatile device whereas I could benefit form it if I eventually working in pure balanced environment. So, shall I keep the 2XX or 2RX? |
Mrderrick, no wonder ARC didn't mentioned this in their reply mail to me. If they have produced such product before, I think they should continue the production as some user may have encounter same issue like what I've been dealing with. Anyway, a Jensen transformer already on it's way. I'll see how things work out. Thanks for the reminder. |
My recommendation may have been overlooked as to its relevance, ARC made several active balanced line converters specifically to address the same issue you are having. The BL-1 and BL-2 balanced line converters. While these are out of production, I do see them come up for sale both here and on Ebay several times a year. You could post a "Wanted to buy" ad. You could then keep your current pre. |
Many thanks to Bifwynne and Syntax for your kind advice on amp selection.
I do have an offer for a Ref 5. Whether buying it or not I think I would still keep the Ref 150. For the JL 5 it kinda impossible to arrange for home audition down here but a single ended amp whether tubes or transistor would be a more "rational" option to me as my CAT already have build in phono stage. If I choose the ARC path I would have to digs for extra money to invest on a good phono preamp.
I do wish that the transformer option would eventually work out as I felt that the CAT-ARC-Maggie's combination sounded quite alright to my ear. It produced romantic and airiness sound stage with good ambient which suited my musical taste. I can't be more happy if it turns out that the Ref 150 does sounds much better when the amp finally able to unleashed their full potential with balanced input signal!
Regards, |
Pakwong ... I still think the Ref 150 is a marginally powered amp for your Maggies. But the most recent posts which speak to the Ref 150 using balanced inputs is extremely important. I cannot overstate how critical it is that you use a linestage/pre with balanced outputs.
Don't know what your budget is. But let me suggest that from time to time, I have seen ARC Ref 3s going for the low $5000s. Even an LS 27 linestage/pre would be a great match.
Last comment. I own a Ref 5 SE/Ref 150 combo. I love my ARC gear. The sound is great. It's built like a tank. ARC provides great customer support. I hope you can figure out a way to keep your Ref 150. IMO, it's a classic piece of kit that will keep its value for a long tim. |
Although only rated 100 watts and have 8 KT120 power tubes just like the Ref 150, people who have been with CAT still think the JL 5 would be an all round winner. Only when think of the 100 watts JL 5 driving the Maggies which has been known to be extremely power hungry, it's normal for a audiophile to try to think "rational" lol I listened multiple times to JL5 and I think it is a great amp. Are you ready to buy them unheard? Try to ask a dealer for loan, they won't do it for free but even when you pay the shipping both ways and an extra for the dealer .... this can be cheap when it will support your decision...but I would still do a comparison with a high powered transistor amp to check what is going on with the higher frequencies... |
Yes kevin, I try to keep rational thinking and focus on the Jensen transformer first.
A friend of mine also recommended JL 5. Although only rated 100 watts and have 8 KT120 power tubes just like the Ref 150, people who have been with CAT still think the JL 5 would be an all round winner. Only when think of the 100 watts JL 5 driving the Maggies which has been known to be extremely power hungry, it's normal for a audiophile to try to think "rational" lol |
Martykl, if I have more than one listening room, I would have keep both! But I still think we audiophile should try to be rational as best as we can lol. The more I went deep into this hobby, the more I realized that we have to put a lot of effort to build a real good sounding system. Two or more system might be overburden to me!
Regards, |
"If you were me, which do you prefer?"
Good question! Both are really fine options.
I really like the idea of trying the Jensen transformer as a stop-gap. Jensen makes really good transformers and this option might work sonically. Might.
If forced to choose one option over the other, I'd go the CAT route because the JL5 would, I feel, do a better job of driving your Maggies. It's not about watts. CAT amps are designed to drive pretty much anything. |
Pakwong,
You're a hobbyist and - if you're willing and able to bite the bullet financially - you might want to consider building two systems. I was in your position and kept both my Juole preamp and my ARC power amp even tho they weren't well suited for use together. I added the ARC line stage and Cary power amps to form two very different systems.
You ask which alternative A'gon posters here might recommend and I'd say that it's really such a matter of personal taste that recommendations wouldn't be very useful, so.... you could build two systems to compare them. If you see the value in each and can afford it, enjoy both. If you prefer one over the other, sell the electronics that come up short.
If you don't want to (or can't) pay for this option, you might try to borrow suitable partnering electronics for each component from a local B&M dealer (if one is available to you) for audition and keep the system that you prefer.
Owning two electronics chains may be expensive, and it may not be a rational decision, but who ever said audiophiles are rational? |
Al, if I were ARC, I would have given the same statement! Thanks again! |
Good answer from ARC. As I indicated earlier, though, a number of other A'goners have reported using the particular Jensen transformer I suggested with extremely good results, in very high quality systems. Although that opinion, as might expected, has not been 100% unanimous. Personally, I suspect it will work out fine.
Best regards,
-- Al |
Answer from ARC:
"The REF150 is a balanced input power amplifier only and requires a true balanced differential input signal to operate correctly. You cannot use XLR to RCA adaptors as these do not generate the required negative phase input signal required for true balanced operation. You have 3 options: 1) Obtain a preamplifier that offers true balanced outputs (an Audio Research Reference model would obviously be the preferred match to your REF150); 2) Use an active SE to Balanced converter that generates a negative phase signal from the positive phase signal by means of a phase inverter circuit. 3) Use a transformer to generate both phases of the signal passively, as you referred to. Our experience is that options 2 and 3 do not preserve all the benefits of option A, with some loss of dynamics and /or transparency to be expected. We do not have any product recommendations for options 2 or 3, so you will need to do your own research to obtain a satisfactory product that performs up to your standards. The REF 150 has a 300K ohm balanced input impedance (150K each leg) and thus presents a very easy load to any device that must drive it."
This again confirmed that I have made a wrong choice. It's a shame I didn't do research before buying the Ref 150. Just pray that the sound will not be too bad with the transformer's option.
|
Yes Kevin, nothing matched the CAT preamp better than their power amp. I also agree with the 5SE/150 matching. For me, the CAT combo looks like a better choice. If I choose the ARC, I will have to buy a phono preamp as the 5SE don't have phono stage option. If you were me, which do you prefer? |
Thanks Al for the detail explanation. Now I pretty much understand the fundamental of both signal type.
Can't wait to try the transformer with my CAT. Unfortunately I still did not received answer from either ARC, Jensen or SMc. Anyway my plan is try on a Jensen first.
Regards |
If you plan on keeping the CAT SL1, buy the CAT JL5 amplifier. If you plan on keeping the ARC Ref 150, buy the ARC Ref5SE preamp. |
Stringreen, if you read through ALL of the above posts beginning with mine on 8-12-14, I think you'll conclude that there is nothing wrong with the amp.
Regards,
-- Al |
Id send the amp back to Audio Research for a look-see. I think thats where your problem is.. |
It's pretty rare when a real problem like that faced by the OP is posted and a straight up creative solution is offered by an Audiogon respondent. Congrats, ZD, you found a high quality, zero cost solution to a thorny problem. |
Nice going ZD! I learned something today. Nice one. |
Thanks. It looks like I finally did something right. It feels strange. I don't know what to make of it. |
Outstanding! And a great suggestion by ZD. Can you explain to a guy like me with almost zero electronic knowledge about how the transformer from Jensen or SMc can actually convert unbalanced signal to true balanced signal? My Maggie dealer also talked about something like pin 1 or pin 2 "hot" in the RCA to XLR cable and he suspected that the termination of my RCA to XLR cable was not done correctly hence the distortion. How true is it? Taking your second question first, the problem you have been dealing with cannot be avoided with an adapter cable, no matter how it is wired. To work properly, your amplifier (and other ARC and other amplifiers that are similarly designed in the relevant respects), must be provided with a balanced pair of signals at its inputs. That means two signals that are essentially identical except that one is inverted relative to the other (i.e., when the voltage of one signal moves in a positive direction, the voltage of the other signal moves in a negative direction, and vice versa). An adapter cable cannot produce those two signals, when it is only being provided with one of them. A transformer can do that, however. A voltage will appear between the terminals that are connected to the two ends of the secondary (output) winding of a transformer, that in the absence of any external connections to that secondary winding would be electrically isolated (i.e., unconnected, or "floating" in EE terminology) relative to the ground of the signal source, and relative to all other voltages or grounds or other reference points that may exist in the system. If the input circuit of the amplifier is designed as a balanced receiver, it will process the voltage that exists between those two ends of the transformer secondary in a manner that is symmetrical relative to the amplifier's circuit ground, which means that it will "see" that voltage no differently than if a balanced source (providing two equal voltages of opposite polarity) were being used. This Jensen white paper, although somewhat technical, goes into further detail that may be of interest. BTW, regarding the transformers I suggested, be sure to note that (as indicated in the manual I linked to for the particular Jensen model I suggested) that particular Jensen model would have to be placed close to the amplifier, and connected to the amplifier with a very short (less than 2 foot) length of XLR cable. The RCA cable from the preamp could be any reasonable length. I believe that no such constraint would exist with the SMc transformer (or with some other Jensen models, although those other Jensen models may not perform quite as well as the one I suggested). Best regards, -- Al |
ZD, your suggestion has save me from selling an excellent amp. Today I loan a XLR cable form the Maggie dealer to try a direct connection from the Wadia which have balanced output and volume control to drive the Ref 150. Guess what? Not only the distortion has disappeared even at maximum volume, the sound it produced was something I never heard in my system!
First thing which I immediately aware of was the dead silence background and powerful bass with very good authority and definition. I never realized low frequency from Maggies can be that great!
Such experiment has confirmed that the ARC do need balanced only signal and that you guys has proved your points to be very true.
Right now, what was left is to find a way to change the CAT output signal to balanced. Al, please forgive my ignorant. Can you explain to a guy like me with almost zero electronic knowledge about how the transformer from Jensen or SMc can actually convert unbalanced signal to true balanced signal?
My Maggie dealer also talked about something like pin 1 or pin 2 "hot" in the RCA to XLR cable and he suspected that the termination of my RCA to XLR cable was not done correctly hence the distortion. How true is it?
Thanks in advance.
Best regards |
My bad, I should have seen that ZD had confused me for the OP. To the best of my knowledge Pakwong's ARC adventure is still unfolding and we'll all have to wait to see how it plays out. |
ZD, the comment you were responding to was from the OP, Pakwong, not from Martykl (who is not the OP).
Best regards,
-- Al |
I didn't realize you didn't have the Wadia in your house. I was just going by this:
"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!"
That's why I thought you had one. Also, I didn't think you sold your 150, it just looked like you may do so. I was just saying to give it a chance before you did sell it. Its a very nice amp. I also didn't realize you had an LS25. I'm sure there's no distortion when use that with you 150. Either way, its good that you were able to figure out what the problem was. |
Zd,
Some confusion here, no Wadia components in my house. I never sold the ARC amp either. In fact, I still use the ARC LS 25/VT 130 SE with Verity Parsifal Encore speakers and a Qsonix front end (which, come to think of it, does utilize a Wadia digital section).
I also kept the Joule preamp paired with Cary 300b mono sig amps and Merlin VSM SE speakers. Analog only from an Oracle/Graham/Graham front end. I still really like all of this gear and have been using every piece mentioned here IIRC for over a decade.
Most of my listening time is now spent in front of an Ohm (sometimes Magnepan) and Rythmik based system with an Onkyo pre-pro and rotating power amplification. Digital sources continue to vary but the analog front end is Acoustic Solid/Rega/Lyra.
Variety being the spice of life and all.... |
Thanks for the response Al. Your explanation was very good.
Martykl,
Did you happen to connect the Wadia directly to your amp? Doing so will allow you to get a feel for how well your ARC can drive the speakers. I suspect that once you get is set up properly with a balanced signal, it won't have any problems driving your speakers. Not only that, its just a very good sounding amp. If it were mine, I wouldn't be so fast to get rid of it. |
Pakwong,
I switched out a Joule Electra preamp for an ARC LS 25 line stage. The sound was a little less romantic or "tubey", but the distortion disappeared. I'm not suggesting that you go this route (like all gear, the ARC stuff isn't for everyone), but a true balanced signal is a MUST for your amp. |
Bifwynne，FYI after some serious listening, I do aware that the distortion were clearly less obvious bypassing the Zeros and used the 4 Ohm tap from the Ref 150 to drive the Maggie. Now the issue has narrowed down to the balanced and unbalanced interaction.
Regards |
Martykl, many thanks for your input. It sure help to further justified the issue with ARC amps. But you didn't mentioned how you finally addressed the issue. Did you changed to a balanced preamp or use a transformer?
Regards |
Jtimothya, I didn't use adapter. It's a specially build RCA to XLR interconnect soldered according to many cable manufacturer's standard for RCA to XLR connection. I've two different set/brand of such cable but posses the same problem. |
Czarivey, My XV-1S is zero hour brand new cartridge. It has just been about 50 hours now. Yes, I have the same problem with my previous XX2 cartridge.
Regards |
Thanks Al for the insight of single ended and balanced design. I'm sure learn a lot from you. What you've mentioned about substituted amp I used was correct. It was a pair of VTL MB125 which rated 55-watts and 100-watts into 5Ω in triode and tetrode modes respectively. It do sounded louder with the Maggie at lower volume in comparison with the Ref 150 but have the same distortion perhaps due to clipping as you suggested.
For your information I've wrote to ARC, Jensen and SMc. We'll see what the answer's like.
Regards |
I didna read the entire thread but any chance the cable could be wired wrong? RalphK once warned me certain XLR/RCA adaptors are wired incorrectly, eg Cardas leave pin 3 floating. |
To rephrase my post:
The OP may or may not have several issues with his system. However, if he's trying to feed a single ended signal into an ARC amp designed for balanced inputs he WILL have an issue very much like the one he describes. Per ARC, he should not drive his amp with anything but a balanced signal.
As a less technical type, I can only gather that the ARC design is unusual. However, I can assure everyone that the relevant ARC amps do, in fact, behave in precisely this fashion. |
P.S. to my previous post. Think of it this way: As you (ZD) are certainly aware, a fully balanced amp puts out signal voltages on both its + and - output terminals, relative to the amp's ground, those voltages being of equal amplitude and opposite polarity. (In saying that, and in saying what follows, I'm oversimplifying a bit by not addressing the fact that an output transformer is present in the case of this and most other tube amps). The design of the amp in question is apparently such that when it is provided with a single-ended input, one of those two output terminals will be at zero volts relative to the amp's ground (reflecting the fact that zero volts has been substituted for one of the two input signals that would normally be present in the balanced input signal pair). Resulting in the voltage difference between those output terminals being half of what it should be. Resulting in the maximum possible voltage difference between those output terminals (i.e., the clipping point) being half of what it should be, or perhaps a bit more than that due to the lessened amount of current being demanded of its power supply.
Put simply, half of the output stage for each channel isn't being used. Visualize it (conceptually) as two amplifiers for each channel, one for the + and one for the -, with one of them receiving no input, and therefore providing no output.
Best regards,
-- Al |
ZD, yes, very uncharacteristically you are missing something :-)
Yes, there will be a gain difference. But that is not the problem. The problem is that the **output stage** of the amp will not be able to deliver much more than 1/2 of the voltage that it must deliver to reach its maximum rated output power without clipping, and therefore the amp won't be able to deliver much more than 1/4 of its rated power. The reason being that it is designed to be driven by a balanced pair of signals, having equal amplitudes but opposite polarities, but the design of the amp apparently is such that when a single-ended signal is provided to its balanced input, one of those polarities ends up being MIA (missing in action) at the output stage.
BTW, given all of that some may wonder why the OP reported that the problem remained when he substituted a single-ended tube amp for the Ref 150. There are two possibilities that occur to me. Either a second problem has been present which resulted in similar symptoms (as I speculated in my 8-12-14 post), or the substitute tube amp was clipping simply because it was not powerful enough for the particular speakers at the particular volume level.
Best regards,
-- Al
|
"It's funny, because this thread is starting to feel like it will spin off much like the old thread I referenced above. Several people posting that a power amp cannot be forced to produce less output because it receives a single ended signal rather than a balanced signal. I undrstand that this result is unusual, but....."
I'm not sure I understand what you are talking about here. Wouldn't the preamp determine if the amp can be driven properly? If you had a preamp with enough gain to compensate for the difference between balanced and SE operation, it shouldn't make a difference. Or, is there something else that I'm missing? |
It's funny, because this thread is starting to feel like it will spin off much like the old thread I referenced above. Several people posting that a power amp cannot be forced to produce less output because it receives a single ended signal rather than a balanced signal. I undrstand that this result is unusual, but.....
For the record, a single ended signal via XLR adapter will cause a particular set of ARC power amps tp distort horribly at relatively low output levels. Per ARC. Per my own experience. Period.
Whether he replaces his preamp or inserts a transformer (as Al recommends) the OP needs to feed a balanced signal to his ARC amp. It's a design quirk, but once my VT 130 SE was appropriately fed, performance went from IMHO unusable (much as the OP describes) to outstanding.
My advice to the OP, don't screw around with any other fixes. ARC told you what to do about this problem. Either do it, or ditch the amp. Trust me, I've been in this precise situation and the solution is a balanced signal. |
08-14-14: Syntax
No, even when some will say, balanced needs balanced ...it is blubber. What you have is a different output or input rating, that's all. And that you can hear when the preamp output is too weak for a balanced amp input for example. But it will not create a distortion. Syntax, I suspect that you submitted this comment before seeing the preceding several responses. It is not blubber. Apparently this and some other ARC balanced amps are designed such that when fed a single-ended signal no signal voltage will be processed through "half" of the balanced signal path. That will cause the maximum output voltage of the amp to approach being only 1/2 of the output voltage corresponding to its maximum rated output. (Probably a bit more than that due to the reduced demand on its power supply). Everything else being equal, power is proportional to the square of voltage. Therefore 1/2 voltage = 1/4 power. As I said earlier, and as the comments by Marty confirm, by providing the amp's balanced (and only) input with a single-ended signal (via an adapter, rather than via a transformer which would convert it to balanced), its 150 watt rating has most likely been reduced to not much more than 37.5 watts. Way too little for the Maggies, and an invitation to clipping distortion at typical volume levels. Regards, -- Al |
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. No, even when some will say, balanced needs balanced ...it is blubber. What you have is a different output or input rating, that's all. And that you can hear when the preamp output is too weak for a balanced amp input for example. But it will not create a distortion. XLR adaptors are very simple, probably a problematic soldering can produce such a distortion but you can check it easily, you can buy these everywhere. The Maggie is something I cannot live without. So do the CAT SL1... Yes, true. But forget SE amps with Mags...these speakers run with nearly everything BUT they love high powered amps. The more power you give them the better they sound. The problem is, high power + good sound is nearly impossible to find. It is the way it is. When I would run the 3.7 today, I would choose the Lamm Hybrid amps. They bite the bullet. |
Thanks Marty. Yes, the other "preamp" the OP tried was an EAR 834P phono stage, which includes a level control but provides only unbalanced outputs. I'm speculating, but having been down this road myself, my guess is that the OP needs a true balanced output to fix this problem. ... or he can convert the single-ended output of the preamp to a balanced signal pair using one of the high quality transformers I referred to. That should work fine; possibly even better than if he were to change to a single-ended amp, as the transformer will eliminate any ground loop-related effects that might otherwise occur. Best regards, -- Al |
Al,
IIRC, that is exactly the result ARC described. In my post above I suggested that the OP try to find an earlier thread on the subject of ARC amps that behave this way. In that thread, there was a long, technical debate as to how power output could be quartered in this circumstance. I don't recall specifics, but after much debate, one 'Goner who is a service tech confirmed the phenomenon by putting a unit on a test bench.
The OP apparently tried to troubleshoot this problem by switching preamps, but my guess is that his alternative preamp didn't output true balanced, either.
I'm speculating, but having been down this road myself, my guess is that the OP needs a true balanced output to fix this problem. |
How many hours in your Dynavector? Have you tried different cartridge/needle?
Did you get your cartridge new/used? |
Marty, thanks very much for that input, which together with Pakwong's experiments seems to confirm the suspicion I mentioned in my post dated 8-12-14. Probably by inputting a single-ended signal into the Ref 150's balanced input the power capability of the amp is being reduced to not much more than 1/4 of its rating. Pakwong, your preamp, amp, and speakers are all very fine pieces. I see no reason why they can't be made to work together, at relatively modest cost. The SMc transformer I mentioned lists at $1895 and is described here. I can recall at least one other A'gon member saying that he has used it with excellent results. Besides converting the single-ended signal to balanced, it would also lower your system gain somewhat, which as alluded to earlier would be a good thing with your particular components. At a lower price point, the Jensen PI2-RX transformer is used in very high quality systems by at least several A'goners that I am aware of. All but one of them reports no perceptible sonic compromise with it. It looks like its price has been recently raised to $345. It is identical to the model PI2-XX, described in this datasheet and this manual, with the exception that it has RCA input connectors. The relevant top-level Jensen page is here. Before ordering either of those devices, it would probably be a good idea to contact the manufacturer and ask him to confirm that the specific model is suitable for use between your particular preamp and power amp, although I'm highly confident that it will be. Good luck as you proceed. Regards, -- Al |
I haven't read thru this long thread so I apologize if this has already been posted:
Some ARC amps cannot take a single need output into their XLR input without major issues. Per ARC, They lack a phase splitter and require true balanced signal in. I know this was true of my VT 130 SE and I suspect that it's the case here.
I posted a thread on this issue some years back that got good responses from some of the techier types here and you should try to find it if only for educational value.
Im not sure, but I believe that the Bottom line is : Find a preamp with true balanced out via XLR if you ant to use you 150.
Contact ARC to be sure.
Good luck |
