Thanks, Rick.
Part of the concern I expressed about that issue was the possibility that if the DAC's volume control would have to be set in the lower part of its range, and if the volume control function is implemented digitally (I don't know whether or not that is the case in the Aeris), its sonics might be adversely affected as a result of what is referred to as "bit stripping." Which can occur to a greater or lesser degree, or not at all, depending on the design of the particular DAC as well as on the particular volume setting. And I raised that point in connection with the particularly high gain that most VAC amps provide, which (everything else being equal) would necessitate a lower setting of the DAC's volume control.
I see that your Rowland Corus preamp provides overall gain that is "Independently Programmable 0 to 20 dB on each input." It would be relevant to the discussion to know what you have that set to in your system, or if it is set to some default value, what that default value is. If that gain is set to a high value it would necessitate a correspondingly lower setting of the DACs volume control, to enable the preamp's volume control to be used in a desirable part of its range. Thereby increasing the possibility of adverse sonic effects due to bit stripping, if the DACs volume function is implemented digitally.
Pending knowing how that is set in your system, though, my guess is that the high gain of the VAC amps would not be a problem for Rinpoche. I say that based on your results together with the fact that the 5 db or so higher gain of the VAC amps, relative to the gain of your Rowland amp, closely corresponds to the approximately 6 db lower efficiency of her speakers compared to yours. Which would result in essentially the same overall system gain, aside from preamp differences.
In any event, though, I would suggest to her that if she obtains a high gain amp such as one of the VACs, and also eventually purchases a preamp, that high gain preamps be avoided. Examples of high gain preamps include many Conrad Johnson models, which provide gains in the area of 25 db or so. A preamp providing a gain in single digits, or at most around 12 db or so, would be a much more suitable choice.
Best regards,
-- Al
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Al,
The gain can be adjusted on the front panel or via the remote. Rowland recommends that you adjust it so the two blue LED lights on the front panel are of equal brightness when used with a preamp. I have it about 4 clicks up from the recommended setting. I have found that to be optimum in my system...great gain, clarity, and it allows me to open up the volume control. Come to think of it, I just changed speakers that are more sensitive. I'm going to adjust the gain to the recommended setting to see which way I prefer. |
On paper the Rowland is a better match for those speakers. I suspect.
Both Rowland and vac gear is top notch sound wise with trade offs other than sound quality as you see which is often the case with ss versus tube gear.
Matched optimally and set up well I would expect more similarities than differences between the two in general though I have not heard the specific models in question.
If you can hear both and compare that would ideal. |
Thank you, Ricred. Good info. Is the adjustment you are referring to internal to the unit, or is it the volume control that is on the front panel?
Rinpoche, gain is the relation between the output voltage of a circuit or component, and the input voltage that is provided to that circuit or component. In the case of a component having a volume control, such as a preamp, it is usually specified based on the control being at its maximum possible setting.
Although for a source component such as a DAC it is probably more proper to refer to maximum output level, or maximum output voltage, rather than gain, since the component is not being provided with an input voltage in the usual (analog) sense.
Best of luck as you proceed. Regards,
-- Al
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You are all so helpful and knowledgeable. Perhaps this is not the forum to ask, but what it 'gain'? |
The gain on the Aeries DAC is adjustable. It clearly states how to adjust the volume when using it with a preamp. When I went from the Bricasti M1 DAC to the Aeris DAC I had too much gain, because I didn't read the owners manual. After adjusting the gain the sound was significantly better.
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One other point, AL is spot on regarding amplifier gain/sensitivity, DAC voltage output and the gain level of a preamplifier (if being considered ). If these parameters aren't adjustable via the components you can have too much system gain. This will greatly limit volume control range to 7 -9 o'clock region which is far too restrictive. Finding the right volume level will be difficult to do.
Charles, |
Hello rinpoche,
This thread has generated very thoughtful and well reasoned dialog. Superb insight from Al as is par for the course. Ì agree wholeheartedly with Jond in that a home audition of the two amplifiers should be provided. This is an important decision and not an inexpensive one at that.
What is more important to you, the power,convenience and flexibility of the Rowland (use with television etc. ) or the "tube magic " rendered via the VAC? Is ultimate sound quality and listening enjoyment the goal? If so it seems as though the tube magic has grabbed your ears and touched your musical soul.
Good luck,
Charles, |
That is so interesting and helpful. I went to the store initially to hear the ARC GSi75. I then compared it to the JR and the VAC, and you are right it is great. And all in one -- but the VAC won me over. That is why I narrowed it down to the VAC or JR for the differences they bring -- tubes vs. SS. If it sounded good with the ARC it will sound great with either of the other two amps. Your comments are so so helpful. Thanks, I really appreciate you sharing that. Makes me very happy. I am using a Devialet 200 at the moment and can't wait to upgrade. It was all I could afford both price wise and space wise at the time. I can now expand and I am very much looking forward to it. |
First off, Al's comments are very informative and much appreciated. Secondly, I only comprehend Al's comments at a layman's understanding. So, with that in mind, I have heard the Sabrina's twice. And both times I was pretty enraptured. The first time was with D'Agostino mono blocks and preamp with a Bricasti M1 DAC. Not sure of wire and other ancillary items, but this absolutely hit the nail on the head for me. This was at The Show Newport 2015. My friend and I both thought it was a very lovely sound. Certainly in the best five or six rooms. I also more recently heard the Sabrina's with an ARC GSi75 integrated amp. So, different room and supporting cast, but again, wow, what a nice full rich sound. Tube magic in evidence. The ARC has its own DAC, which I think they used, and this was a very nice complement for the Sabrina's. For only 75 wpc, these tube amps had an iron grip on the bass and I was pretty astonished as were others as well. I heard them at at a high end get together and there were a number of people who felt this was one of the best setups in the room; there were 6 or 7 total and they were nearly all Wilson with ARC gear. This particular Sabrina/ARC GSi75 integrated pairing also one of the least expensive at that get together. I still think a lot about the Sabrina's with an ARC GSi75 integrated or the D'Agostino gear. Very nice indeed. My one caveat concerning the Sabrina's with an ARC GSi75 integrated is that the amp takes 45 seconds to power on and since my system is used with TV/Movies as well, that'd be a no go as my wife would not accept that. Never hurts to dream though. BTW, most of the time I have seen the Wilson line displayed they were being paired with ARC gear. I have heard most of the floor standing line and I thought the Sabrina/ARC GSi75 integrated was near the best. On that same day I heard the Alexandria XLF with D'Agostino mono' and pre and it was very engaging but to me the cost differential seemed unjustified. Of course, this is just my own opinion. Good luck in your journey, hope it is a lot of fun for you. |
I am very appreciative. I did write to Kevin and he thought the Sigma would be great. He also said the Phi 200 would be great, but both would be excellent choices. The used Phi, however, would not be warrantied as far as I understand because it is coming from the US to Canada, so that sort of stopped me from pursuing it fully. As I mentioned, I don't have experience with tubes. This is a new adventure for me. I am a bit nervous but also trying not to be intimidated (as a woman I am not as sure about biasing and rolling and tweaking tubes -- yet, but I am sure I will learn). All of your suggestions are valuable. The best thing would be if the store would come to my house to audition the JR and VAC amps. That would be great. Are there any other amps I should be looking at that will be reliable and easy to run in this price range (with the Sabrinas)? |
Although the specs on the Phi 200 aren’t complete enough for me say with any certainty, I suspect there is a good chance it would avoid the issues I raised about pairing the Sigma with the Sabrina. For that matter, I can’t be sure that the issues I cited would be problems with the Sigma either, but they are certainly significant concerns IMO.
Probably the best thing to do if you want to consider the Phi 200 is to call Kevin Hayes at VAC and discuss it with him. In doing so, be sure to point him to the Stereophile measurements of the Sabrina that I linked to. The question, basically, is not whether the amp can drive the speaker, it is whether or not impedance interactions would cause the pairing to not be a good one in terms of sonics.
However another concern that just occurred to me, that is applicable to the Phi 200, the 200iq, and most or all of the other VAC power amps, is that they have particularly high gain, while the Aeris DAC has a specified maximum output level of 7 volts, which is extremely high. (It isn’t clear, though, if the 7 volts applies to the balanced output, the unbalanced output, or both).
The gains of the VAC amps are about 5 db more than the gain of the Rowland 625 S2, assuming balanced connections are used in both cases, even though the Rowland is much more powerful. (And the gains of the VAC amps from their unbalanced inputs are even higher). The combination of high amp gain, very high DAC output, and the additional gain of an active preamp (if one is used) may cause you to have to set the volume control(s) on the DAC and/or preamp to settings that are undesirably low in their ranges. Which, in addition to possibly compromising the resolution of the volume adjustment, might degrade the sonics of the DAC, especially if its volume control function is performed in the digital domain.
Although on the other hand the somewhat low sensitivity of the Sabrina will be helpful in that regard, to some extent.
Apologies for citing so many concerns and negatives in my posts, but as I see it these are things that should be considered before making such a significant investment.
Regards,
-- Al
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There is a VAC Phi 200 used for sale. I could pair that with a new VAC pre-amp (an entry model) if you think that might help with the issues you are describing. Wilson Audio approved the Sigma SE but that doesn't mean they have paired them. In terms of an in-home audition, I think this is a very good idea. The Rowland gear is, I think, less of a problem but I would loose that magical tube sound. Yet, I would gain in ease of use and given I will be adding in TV, maybe that is a good thing. See why I started this thread!!! It is like comparing two delicious desserts, and you can't eat both of them. Would love more of your excellent thoughts on this!! Thanks |
Do you have suggestions for other amp pairings with the Wilson Sabrinas? I am open-minded at this point. I suspect that Knghifi’s suggestion of the VAC 200iq would avoid the concerns I expressed about pairing the Sigma with the Sabrina. Especially if two of them were used as monoblocks, but possibly also using just one in stereo mode. I say that in part because the 200iq includes a third output tap, designated as being for 1 to 2 ohm loads. That in combination with the reference in its description to 6 db of feedback suggests that the output impedance of that tap is low enough to avoid the tonal issue I referred to. It is also more powerful than the Sigma, of course. A risk of going that route, however, would be the possibility that having a preamp in the chain might ultimately prove to be sonically desirable, and a preamp that would do justice to the rest of the equipment would add up to very big $ in combination with two or even one of those amps. See this thread for some discussion of using the Aeris with and without a preamp. From a technical standpoint I would also expect something like an ARC Ref150SE to be a compatible pairing. ARC tube amps tend to have lower output impedance than many or most other high quality tube amps, as well as having very robust power supplies. However its size, complexity, heat generation, cost, and again the possible desirability of a preamp may rule it out. And I have no knowledge of how well its sonics would synergize with those of the Sabrina. I’m not particularly knowledgeable about VTL products, but the fact that most of their amps have only a single output tap, nominally rated for a 5 ohm load although claimed to be suitable for 2 to 8 ohm loads, would give me pause. Regarding Rowland solid state amplification, I have no experience but FWIW a number of members here whom I consider to be particularly credible, including Ricred who posted above, use it with great results. As far as I know there are no technical issues that the Continuum S2 or the Rowland power amps would present in your application. Good luck. Regards, -- Al |
Thank you -- I will ask if they will do it. When I asked one of the guys in the shop he said, 'bring in your speakers'. They have been around a long time so I will see if they are willing to do it. It is one DAC and 2 amps. Should be worth it for a purchase of this magnitude, as you rightly say. That is a great suggestion. Thanks. |
rinpoche for a purchase of this magnitude any good store should let you do an in-home audtion, I assume the store is local to you? Perhaps the owner can bring the amps over and at least do an audition with your speakers if he won't lend you an amp? I would expect better service than what you're describing for a good brick and mortar shop.
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By the way, do you have suggestions for other amp pairings with the Wilson Sabrinas? I am open-minded at this point. |
Thank you. I appreciate the detailed information. It is well beyond my comprehension, but I do understand your bottom line advice. I have not heard either amps with the Wilson speakers. I would have to take them to the store and I don't really think I can manage that. The store does not seem open to letting me bring the amps home. I listened on bigger Focal speakers -- and more expensive Focal speakers. They both sounded very good, but tubes (as I am realizing) have a little magic that SS doesn't. But, the JR was really good as well. The owner of the store thinks it should be fine with the Wilson's. I emailed the Wilson people and they also like VAC, VTL, and ARC with the Sabrinas. Thing is, everything costs so much (to my mind) and I want to get it right. Your help is part of the process and it is appreciated. |
I have listened to Jeff Rowlands integrated with the Aeris DAC. And the VAC Sigma integrated with the Aeris DAC.... I have heard the VAC Sigma 160iSE and the JR 625 upgrade both with the Aeris as the DAC.
Am I correct in inferring that you have not heard either amp with the Wilson Sabrinas? While I am a big VAC fan, I would have some concern about how well suited the Sigma integrated (and many other tube amps, especially those which use minimal amounts of feedback) may be for use with that particular speaker. Per John Atkinson's measurements:
My estimate of the Sabrina's voltage
sensitivity on the tweeter axis was 88.2dB/2.83V/m, slightly higher than
the specified 87dB. Wilson specifies the Sabrina's electrical impedance
as 4 ohms, with a minimum magnitude of 2.53 ohms at 139Hz. My
measurement of the impedance is shown in fig.1: the value (solid trace)
varies between 4 and 6 ohms between 250Hz and 4kHz, and the minimum
magnitude is 2.44 ohms at 135Hz. However, there is also a combination of
4.44 ohms and a capacitive phase angle of –58° at 72Hz, a frequency
where music can have considerable energy; this will place a significant
demand for current on the partnering amplifier. Although the output impedance of the VAC integrated is not specified, I suspect that it is not particularly low, because I would expect a VAC design to avoid heavy-handed application of feedback. Given the speaker's impedance variation from about 2.4 ohms in important parts of the bass region to substantially higher values at higher frequencies, especially in the treble region (as shown in Figure 1 of JA's measurements), the result of that combination is likely to be some degree of weakness in the bass, and some degree of over-emphasis of part or all of the treble region. Also, given the speaker's 4 ohm nominal impedance be aware that the measured sensitivity of 88.2db/2.83V/1m corresponds to only 85.2db/1 watt/1 meter. Which suggests that 86 watts of amplification may not be enough, especially if your listening includes material having wide dynamic range, such as well recorded minimally compressed classical symphonic music. Good luck, however you decide to proceed. Regards, -- Al |
I suggest buy the one sounds best to you. For a tube amp, VAC is relatively low maintenance. Replace output tubes periodically and if one blows, replace along with a fuse.
Sigma 160iSE has only 4 output tubes so heat is probably not an issue and inexpensive to replace when worn.
If you're considering 625, definitely checkout VAC 170iq and 200iq. You can roll KT88. KT120 and KT150, real time biasing and when an output tube blows, IQ system trips before blowing a fuse so just replace the bad tube. I know an experience audiophile has 2 200IQs and found them a big improvement over previous models.
If I was in the market for tube amps in this price range, 2 200IQs will be HIGH on my list.
Aeris DAC can drive amps directly so only you can decide if a preamp is necessary. I always prefer a preamp in the chain.
I have an all tube system so would go for VAC.. Summer is here and last night I rotate SS amp back in the system. It sounds excellent but NO magic. SQ will improve when the tube amp sound is no longer fresh in my mind ... happens every summer. :-):-)
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Thank you for saying that. I really appreciate the advice and experience of this forum. Yes, I have been told that the VAC will plug and play and then, of course, need servicing, but I also want to use it to watch/listen to films and even TV. That means, the tubes will be on more often than if I only used it for listening to music. Do any of you use a tube amp for film and TV? |
You said it yourself. If you want fabulous get the Vac. If you want very nice get the Rowland. Vac amps are pretty much plug and play
Alan |
Keep discussing guys- I have always wanted to demo both VAC & JR gear. |
I hope you will indulge me a bit here. I have heard the VAC Sigma 160iSE and the JR 625 upgrade both with the Aeris as the DAC. I am a bit nervous about tubes. This would be my first time with a tube amp. I do agree that the VAC is amazing. The JR is also good and it is a bit easier given it is plug and play and no tweaking, changing tubes, etc. is required -- so are tubes really difficult? Is the sound worth it? I agree that the VAC is fabulous but the JR is also very nice. Please say more on the topic if you can? |
I have heard the vac integrated at length and it is a great amp. I also prefer tubes over ss for the Wilsons
Alan |
I have all Jeff Rowland components(625 S2, Corus preamp, Aeris DAC) driving Monitor Audio PL500s. Despite what anyone says, there aren’t any absolutes in Audio; let your own ears decide.
I had the Continuum S2 integrated amp and now the 625 S2. I submit the 625 S2 is a decent step-up from the Continuum S2 that should be easily heard, but relatively expensive. You can use the Aeris DAC to drive the 625 or use a preamp. |
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