This is for Georgehifi especially but others can chime in.
I am buying Dynaudio C-1 Platinums and would like an ideal amp. Which would you choose? I prefer solid state. Separates or integrated. If you could recommend a few optimum choices that would be great. Based on my short couple years on here you strike me as very knowledgable on the subject. My dealer wants me on Pass Labs. Incidentally right now I have the Devialet 400 and I’m pretty sure you are not a fan of this type of amp. Any of your wisdom is appreciated. Thanks, Mike
Showing 35 responses by georgehifi
bubba12 OP160 posts01-26-2018 10:07amI’ve sold the Devialet 400. Frankly,I didn’t like it.Doesn’t surprise me, I’ve yet to hear a class-D yet that’s sounded right in the upper mids/highs, either too rolled off, soft, cold or harsh depending on the switching frequencies filter’s filtering characteristics. Great in the bass and upper bass though. Yes the XA25 is a little short on power, should sound very nice (being high bias Class-A series) from low to medium levels. Also it’s gain is only 20dB so an active preamp with bit of gain is needed to partner with it. The XA60.8 would be my pick for you, still the high bias series, and should have enough power for the Dynaudio C-1 's, and it's a higher gain than the XA25 at 26db so you could get away with a passive preamp and save a stack on money. Cheers George |
PS: Love these older class-a monsters, Mark Levinson ML2 monoblocks, only 25w Class-A into 8 ohms, nothing more, but said to be able to do the "almost" doubling wattage act down to 1ohm https://ucarecdn.com/c5da1bf6-48bb-420e-b088-b6dbf0dceb7a/-/scale_crop/840x630/center/ http://4.bp.blogspot.com/-9uGHPSseR-w/U3aWYTrghsI/AAAAAAAB8yI/XxdvN_K7-jk/s1600/ML2a.JPG Cheers George |
I love the sound of well made Class-A. Way back I built some very large pure 100w pure Class-A ones using 20 x Hirel EB/ED 204’s BJT’s per channel and a 5kva transformers 500,000uf per channel, that were a 3 man lift, they were water cooled because of the huge amount of heat that needed to be dissipated, and were size of a large coffee table. http://www.diyaudio.com/forums/parts/76846-whatever-hirel-transistors.html My preference is like Nelsons (if you delve into his past) for the sweetness and effortless sound of Class-A which will come from in a smaller way from the XA A/B amps. The XA series has more Class-A less Class-B The X series has less Class-A and more Class-B So it all comes down to which flavour of "Class" your drawn to. For me it would be for the XA’s. Cheers George |
bubba12 Why not stick with the Devialet 400 which you have, or the Pass Labs you said you could get? BTW which Pass Labs was it? All are good. Cheers George |
I've noticed the same approach by a couple of other manufacturers and also found their stereo amps sound more musical than their comparably power monos. Yes a few disadvantages happens with bridging a stereo amp, while you get more 8ohm wattage the drive-ability into low impedance's is greatly diminished. The damping factor (output impedance) of the amp is raised, therefore not having as good control over the bass. And the other is the distortion of the amp increases, and I believe also the noise. Cheers George |
bubba12 OP156 posts01-25-2018 6:37pmI need opinions on the Odyssey Stratos Extreme mono amps I’ve come across some Odyssey amps, a stereo and the mono-block version of it here in Australia, that a friend bought in who was going to be the Au agent for them. I can’t remember which ones they were but they were the upper end of the range. We listened to them, with a group of our audio society friends and were all in the opinion that the stereo version sounded better than the monoblocks, even through the very hard to drive Infinity Systems Renaissance 90 Signatures, oldie but a goody. After that listening session, we peaked under their skirts, and what I pointed out to the potential agent was that the monoblocks were just bridged versions of the stereo one. Now I don’t know if this bridging of the stereo ones for the monoblocks is done right through the range. But if you post a photo of the inside on one of the many free image hosting websites I can let you know, if they are just bridged stereo’s or true monoblock amps. Cheers George |
You two really need to update your semiconductor knowledge. Upvoted by, MSEE Electrical Engineering & Circuit and System, Master of Science in Electrical Engineering (2015) and M.S Electrical Engineering, University of Southern California (2017) Pros for BJT: "BJT’s at the same physical dimensions and price can usually give you a lot higher speed, as they have very little input capacitance. BJT’s can give you a lot higher gain. Just take a bunch of components and compare them, and you’ll find the BJT’s give you better gain characteristics and therefore require fewer gain stages. BJT amplifier stages are much more linear than MOSFET amplifier stages, as the gain doesn’t depend on the bias voltage. This gives better fidelity. BJT’s are capable of handling higher output currents for signal outputs and can have lower output impedance. In amplifiers intended to drive a low input impedance load or deliver significant amounts of power, this is a huge advantage. Many of the highest quality op amps are made with a BiCMOS process using a BJT pair for the output buffer stage." Cons for MOSFET: "Not as high of fidelity as BJT, since the gain will vary slightly as you increase the input voltage (that is, it will generate some very weak harmonics). Input capacitance. The higher the gain, the greater the input capacitance thanks to the Miller effect. Can’t drive a low-impedance load very well. Low gain per part, which often means more amplification stages are necessary for higher gain, even when using advanced design techniques. Each amplification stage adds noise -- that is, you can never, ever get a better signal-to-noise ratio at the output than at the input." I believe the OP has everything he needs, and doesn’t need the BS from the F5/Mosfet lovers, which I’ve heard and are great amps, if used within their comfort zone with preamps with high’ish gain and speakers not too low in EPDR load impedance’s and moderately efficient, because of wattage limitations. Hope you got everything you needed bubba12 Unfollowing this corrupted thread. Cheers George |
I just can’t stand seeing BS put up, and have to give the truth. There is no such thing as an amp that can double it’s wattage the way he quoted. And if you believe Mosfets can do current better than BJT’s then your just as bad. As far as Ralph he great and we agree on many things, except for his instance on Zero auto transformers being a fix without any negatives, which they are far from, and are just a bandaid fix for a problem of not having the right amp for a given speaker. Cheers George |
We're talking current delivery, and BJT's (bi-polars) will do current better than mosfets can. Ask the current amp kings EG: Krell, Gryphon ect why they use BJT's, and they don't have problems with thermal runway, because they are good designers, and don't get it, even with the massive Class-A bias they have. Your done. |
kosst_amojanWhy do you keep assuming I've used a passive? I never have and I never will.Really!!! now this is a laugh, from statements like this below. kosst_amojanCan we clear something up? All passives basically suck. You really need to, with the right setup, and not using such a low gain amp as you have. Then you will have an ear opening experience, and will be enlightened. End of story. Cheers George |
Oh? You think 10kOhm is a great impedance for a source to be looking at? 99% of sources, Yes, Yes and Yes again, unless you have a tube source with massively high unacceptable 3kohm'ish output impedance. Just don't tell me how uncolored they are because that's a demonstrably false statement.You'll never know, with your low gain amps, and using 25kohm passives, you can take that to the bank. . Cheers George |
You state "All passives basically suck". You have a problem sunshine that you need to address before you can make such a statement. You you say your power amp gain is only 15db, this is half of what most amps are and is not passive friendly. Who said 25kohm passive??? You should not have tried 25kohm passive, should have been 10kohm, as this is a match for any poweramp with industry standard of 47kohm input impedance or higher, and your source hopefully is low output impedance, not high impedance tube. So basically you suck it up and don't even go passive and complain about them or you fix your problems and maybe just maybe you may see the light. That passives can be more transparent more dynamic and less coloured than any active pre with or without gain. Cheers George |
My F5 has about 15.5dB of gain.Say yes!!! about half normal power amps. Which is very low for a poweramp, and why your experience with passives is understandable, and why you need the gain of an active pre. As Nelson said: " "We’ve got lots of gain in our electronics. More gain than some of us need or want. At least 10 db more." And there’s no need for active buffers, on passives if there’s no impedance mismatch. Cheers George |
All passives basically suck.Your First Watt amps have very little or no gain, I can see this maybe your reason behind this statement. But that’s your opinion, and you are entitled to it. It is a totally incorrect statement if there is no impedance mismatch or gain problems as First Watt amps will have, there is only transparency, dynamics, and distortion advantages over any active/buffered preamp with or without gain. As quoted by Nelson Pass: " What could be better? Hardly any noise or distortion added by these simple passive parts. No feedback, no worrying about what type of capacitors – just musical perfection." Cheers George |
passive preamps commonly suffer from their own problems that can easily affect the sound, Rarely, not commonly, around 10% of the time there can be mismatched impedance's when the source has tube output stage which is too high in output impedance, or it's output coupling cap is too small, which will give a very high output impedance at low frequencies. These types of sources direct, would be also mismatch into many Class-D amps as well, as many are 10-20kohms input impedance, just like a passive. Cheers George |
Parasound JC-1s and felt it was a little leaner than with a preamp. Would this be the same thing?Any active preamp will impart it’s own colouration on the source, and they all sound so different, that’s why so many chop and change these looking for the right colouration that suits them. I say let the source be heard for what it is, without any added colourations with a transparent passive preamp, and if you then don’t like it change the source, as the source is where it all starts, and not to add another colouration with an active preamp trying to fix it. Remember a very good 70’s saying from Ivor Tiefenbrun (Linn Sondek fame) "First get the source right and your 1/3 of the way there, if you don’t it’s a never ending battle to get the truth" Cheers George |
What makes you say that these to preamp’s are comparable?Didn’t say they were comparable, but what I did say is the Freya has the better volume control system of the two. And if you know me that’s what I’m heavily into with my product (passive preamps). As most sources have enough output these days to make any poweramp run to full output (clipping). without a need of an active preamp with even more gain and noise that’s not needed. A quote from Nelson Pass himself: "We’ve got lots of gain in our electronics. More gain than some of us need or want. At least 10 db more. Think of it this way: If you are running your volume control down around 9 o’clock, you are actually throwing away signal level so that a subsequent gain stage can make it back up. Routinely DIYers opt to make themselves a “passive preamp” - just an input selector and a volume control. What could be better? Hardly any noise or distortion added by these simple passive parts. No feedback, no worrying about what type of capacitors – just musical perfection. And yet there are guys out there who don’t care for the result. “It sucks the life out of the music”, is a commonly heard refrain (really - I’m being serious here!). Maybe they are reacting psychologically to the need to turn the volume control up compared to an active preamp." Cheers George |
Pass Labs XP 12 preampGood choice also, even though it’s $5,800.00 nearly 10 x the price, but then if you’ve got it, spend it. It would be interesting to A/B the two! As the volume control in the Freya is better, being 128 positions relay controlled, instead of the Pass having just a good quality potentiometer. Cheers George |
bubba12 Excellent choice Bubba, with the XA-60.8 monoblocks, they will have high biased into Class-A for a very nice sweet transparent sound. And they bat well above their specs. Team them up with a $699 Schiit Freya preamp, which has three different sound flavoured outputs, passive ,tube or solid state you can choose on the fly and it’s remote with balanced or se output and inputs. http://www.schiit.com/products/freya Stereophile: The XA60.8 considerably exceeded that power, delivering: 150W into 8 ohms 240W into 4 ohms 380W into 2 ohms Cheers George |
The **partial** solution is to short out the speaker terminals of the unused speakers, so their drivers can't move. This really helps. This is correct Ralph, and does work to a degree, and only if the bass unit is not cap coupled. But I was waiting for the light to come on from Audiotroy to tell us he does this, which never happened. So his knowledge of this and having multiple speakers in the room to demo to the detriment of the sound is limited. Cheers George |
My post criticizing Audiotroy for taking over and dominating threads for salesmanship here was removed. I don’t know why as there were no curse words nor were there insults.He would have reported your post. And he maybe a small paid advertiser here somewhere in Agon maze of pages which "can" on other forums I notice influence the moderators. Cheers George |
One of our sound rooms has 54 components in it. How can anyone make a serious judgement about the sound when there are more than one pair of speakers in the room? as all the other unused speaker cones are happily bouncing back and forward in sympathy with the ones being used, you may as well have drummy walls, floor and ceiling. Cheers George |
they don’t require as much thermal runaway protection. You keep saying that and they have it, talk to Gryphon and Krell who make some of the highest biased Class-A amp there are, and what do they use??? BJT’s WHY??? Because they give the best current ability. And 4 X 150w pure Class-A that I made, BJT’s, and yes they were water cooled if you have doubts about getting rid of the heat. Sure if your a dumb a**e and can’t design for s**t you can get thermal runaway I expect that from a backyard diy'er, but you don’t see any of the above doing that. And they will, I repeat, WILL out current any Mosfet amp into low impedance’s. Sorry but you have your head in the sand if you don’t know this. Cheers George |
Why do you think BJT’s are good for passing high current? If you don’t know this, then well??? Look at any amp "tested" that can almost double it’s wattage for each halving of impedance right down to 2 or even 1ohm and 99.99% of the time it will be an amp that has Bi-Polar (BJT) outputs. Go back to giving audiotroy grief, and stop preaching your F5, yes it’s good but there are many better for delivering big current into low impedance’s. They’re the most prone of all devices to thermal runaway. Tell Gryphon, Krell, Agostion ect that little furphy. Cheers George |
@georgehifi What do you think of Classe CAM 400 Monos? I like them very much "but", what I didn’t like in one of the higher end older models, was they used an input opamp for the balanced circuit which then fed to the discrete single ended circuit. So the balanced in was just an added opamp in the signal path, compared to the SE in, no guesses which sounded better. Cheers George |
bubba12 Hi Mike, the C1's tested at are 85dB, so you need at least a 100wpch amp or higher depends how loud you want to go. But a worry is that they need a bit of current as well, at around 80hz to 110hz, and that's the power (current) region, because they are not only 4ohms but also have a dip of -40degrees - phase angle as well in this region. This could have an EPDR of around 2ohms as seen by the amp. https://www.stereophile.com/images/archivesart/1107DC1fig1.jpg Myself I'd go for the Pass because I have a thing with Class-D for now, but both should work fine with the C1's, I'd try to audition both in your own system, to see what you prefer. I'd say the Pass will have the sweeter more believable upper mids/highs, but the Dev "could" have the better bass. Cheers George |