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What would happen if you presented the SDS-470 with a 16 ohm load?
Forgive if this is not the right place to put it, but I decided to sell my CDA-254L kit and black par-metal chassis with connectors. Was thinking $200 plus fedex ground to your location. Any takers?
You should put that here ---> http://www.audiocircle.com/index.php?board=103.0
SDS-450 amps up and running again with the revised boards. Sounding good and no heat issues thus far (left them running all night).
In general, a higher ohm rating is easier for an amplifier to deal with than a low one, so I imagine it would be fine.
First off, how about if you term it more correctly. Higher impedance.Sure, higher impedances are generally easier on an amplifier, but not necessairly better as far as frequency response and damping factor are concerned.You'll find that some amps work 'best' into some specific load, probably depending on the output devices themselves.
Hi all,This is my first post on this board, so perhaps I should introduce myself. My name is Craig Young, and I have been searching for a new power amp for my system, which consisted of an Audible Illusions Modulus 2D preamp, a Counterpoint SA-220 power amp (now deceased ...) driving a pair of Apogee Centaurus ribbon hybrids. I am currently using a friends set of Bel Canto REF 1000M monoblocks to drive these speakers and am A/Bing them with my brothers Odyssey Stratos Plus Class A/B amp. Source is an OPPO 981 DVD / CD player as well as my home theater system which is driven by a Lenovo T61 laptop in a docking station. My listening environment is very sub-optimal, although it is potentially a very good room. It is not a dedicated listening room, however, and has too many hard surfaces (bare walls, no draperies, hardwood oak floor, etc.). It does have an 18 foot vaulted ceiling, and with some acoustic treatment would likely make a very good listening room.My background is in music, and I was formerly a professional classical musician. I am currently working in electrical engineering, doing building power and lighting design.I have done a bunch of reading on this board and others. I originally considered buying another used amp such as a set of Bel Cantos, but cannot currently justify the price. I am also not totally sold on B&O ICEpower modules. So, I began exploring a DIY project, as I have some DIY experience, and my twin brother has extensive DIY and design experience, and is willing to help out, or even to just build the whole thing.I originally toyed with Hypex NC400, but the realization that the finished product would run ~2K caused me to turn in this direction. I have read this entire thread as well as everything I could find on diyaudio about ClassDAudio.I spent some time corresponding with Tom yesterday to verify what amp he felt could drive my Apogees (84dB sensitivity and 5/3 Ohm nominal / minimum impedance). I also wanted to verify that my tube preamp, which has about an 1800 ohm output impedance, would work properly.Based on my discussion with Tom, I placed an order this morning for an SDS-254 kit, minus power caps, which I am replacing with (6) 10,000 uF Panasonic caps. I will be using a Par-Metal 16 x 12 x 4 enclosure, and will use single ended RCA outputs from my preamp to drive balanced XLR inputs on the power amp. I will be building my own interconnect cables using (probably) Belden microphone cable.Thank you all for your comments in this rather lengthy thread, and I look forward to posting listening impressions.
Some suggestions:If your sources have volume controls, sell the Audible pre. Or buy a resistor stepped attenuator (It can have a switch between different sources) with one vishay in series for good sound and sell the Audible pre. (I used to have the Audible Illusions Modulus 2B preamp then a CAT pre. They are both blurr machines.)The SDS may have enough gain to make up for the lack of a pre. But with those insensitive speakers I'm not sure. Have Tom do the calculation.Why not spend $20 more (you should get more than that for the pre) and get the SDS 258 and get twice the power and +3dB, sounds about twice as loud.I've had 2 different pair of Ice amps, 200w and 1000W, both modded. My unmodded SDS 258 beats them easily.Why run the inputs as a psuedo/quasi balanced line? Better sound? Or preparing for when you have real balanced input from a source?
Thanks for the suggestions. If you look closely at Audible Illusions, the Modulus 2D is significantly different from the 2B or 2C. I would have to respectfully disagree with you as to it being a "blur machine". I have used this preamp for the past almost 20 years and love it. I like the idea of a tube preamp with a class d power amp, but I will evaluate that over some longer time period before making a change.As far as the SDS258, I talked to Tom about it, and he did not recommend it for my speaker (yes, I gave him the specs for them). He said this:"Yes, the SDS-254 should drive your speakers just fine. I think with the ratings of these Apogee speakers, you should get about 200W MS up to 250W RMS from this amp.I don't recommend the SDS-258 for these speakers as its not made to drive the loads these speakers are capable of. If you want more power, we do have the SDS-470 (not on our website) that is 300W RMS per channel."In terms of running balance versus unbalanced, according to Hypex, for example, this arrangement benefits unbalanced sources almost equally to balanced sources. A number of posts on this board indicate that use of the balanced option improves soundstage and air in user systems here. Plus, the reality is that with the SDS-254 I can do either by simply removing a jumper or replacing it. Finally, it provides future proofing as well.
No issues with long term listening, ive had my SDS254 for well over a year now.What caps are you installing?
Hi all,Here are a couple of in progress pics of my SDS-254, in a Par-Metal 16x12x4 case. Also, I do have a couple of questions.1.) My kit came with the Honeywell gain controls, but no mounting hardware or knobs. Is this normal? I have an email into Tom, but he has not responded yet.2.) Any comments on this amp as to long term listening? Any fatigue or glare in the high frequencies noted with this? The information in this thread suggests that it is a very good sounding amplifier, but I thought I might be able to get some longer term comments.Finally, This is a drawing of my layout.
