olds1959special Posted May 28 Share Posted May 28 I just found four Kenwood L-05M mono block amps, each rated at 100 WPC that I'm using to power my Vandersteen 2Ci's. One pair was recapped, and the other pair is a bit newer with an unknown service history. Both appear to perform well. When I switched around the bass and midrange/treble I noticed very little difference between the pairs of amps. They are dead quiet too. Interestingly, both pairs came from the studios of famous musician/engineer/producers! Apparently these amps are known for powering studio monitors. This is a lot of power, even more than is recommended for these speakers, according to the Vandersteen manual, which states 40 - 160 watts per channel, and I think this would be 200 watts per channel. I wanted to give a review of my experience with them in my living room. First off, the sound seemed to be on a dark side so I boosted the tweeter contour control by 1.5dB. Going up to 2dB sounded unnatural. The source is a SMSL D0100 Pro (filter setting 2 - linear phase fast roll-off) with a 0.5ft solid silver conductor IC going to a Schiit Saga S pre-amp (active mode on). The two sets of outputs from the preamp go to the amps by way of WBC Mogami 2964 cables with Amphenol connectors. Then I have 2 sets of 4' 14 AWG Gear-It speaker cables per speaker from bass and midrange / treble going to the amps, with banana plugs on the speaker side and bare wire to connect to the amps, since they can't use banana connectors. I am listening about halfway up on the volume setting most of the time, or a little more. The sound is full, deep, relaxed, and with the tweeter adjustment there seems to be enough treble, but this is not a bright speaker. I have played with the toe-in as well. Right now, they are toed in 2". The speakers are about 6 feet apart, and I am about 6 or 7 feet away. They are 3 or so feet from the back wall. There is a wooden entertainment unit in between the speakers. I tried to move them out in front of the unit so the sides don't block the sound. My space has decent acoustics since it has high ceilings and is not shaped like a box, but rather is open on one side. I am using the metal speaker stands that I believe are filled with lead shot. I'm listening to Diana Krall (Glad Rag Doll) in 96kHz / 24-bit and it's sublime. The naturalness of the sound and the presentation is remarkable. The rich tonal qualities, with full, deep bass, are just right for music. I use Quboz these days, (I was able to transfer my libraries over from Apple Music and Tidal with Soundiiz.) Now onto some Tom Waits... 1 Link to comment Share on other sites More sharing options...
Holmz Posted May 28 Share Posted May 28 27 minutes ago, olds1959special said: This is a lot of power, even more than is recommended for these speakers, according to the Vandersteen manual, which states 40 - 160 watts per channel, and I think this would be 200 watts per channel. If you ran 10 amps of the 100W in parallel to each speaker, it would still only be 100W that the speaker consumes. To get 10x the power you need to up the voltage of the amp’s rails. All that happens with running the 10 amps in parallel is that each amp just puts out 1/10 of the current. If it was possible to dailychain those amps in series then it would be 1kW or maybe 4kW. But if you went with a sub, and the HPF, then you could effectively double the 100W to 200W… as the sound can be cranked up… and the extra 100W comes from the sub carrying its part separately, but the higher registers either have headroom, or can go 3dB higher before they hit the rail. 1 Link to comment Share on other sites More sharing options...
olds1959special Posted May 28 Author Share Posted May 28 9 minutes ago, Holmz said: If you ran 10 amps of the 100W in parallel to each speaker, it would still only be 100W that the speaker consumes. To get 10x the power you need to up the voltage of the amp’s rails. All that happens with running the 10 amps in parallel is that each amp just puts out 1/10 of the current. If it was possible to dailychain those amps in series then it would be 1kW or maybe 4kW. But if you went with a sub, and the HPF, then you could effectively double the 100W to 200W… as the sound can be cranked up… and the extra 100W comes from the sub carrying its part separately, but the higher registers either have headroom, or can go 3dB higher before they hit the rail. I'm not sure I get it. If I just used one amp per speaker, and connected the bass and midrange/treble drivers together, wouldn't that give me half the power? Link to comment Share on other sites More sharing options...
Holmz Posted May 28 Share Posted May 28 (edited) The amplifier provides the voltage that drives/pushed the current through the coils. Say you have a full 32v at the amp’s rails, and the speakers are 8 ohms. Then with V=IR, you get 4 amps flowing. Watts = I*V… so 32V * 4A =128W What you get with 2 amplifiers is that each amplifier then supplies 2 amperes each, but still at the same 32v at the speaker terminals. So each amplifier supplies 64W of the 128W being shoved through the speaker… Now if we put 10 amplifiers in parallel and each amplifier supplies 12.8W at 4/10ths of an ampere each. (4 amperes total across 10 amplifiers) And the speakers still only dissipates 128W in total. With a HPF and a Subwoofer, the speaker still only dissipates 100W max, but at that 100W there was another 100W that are exclusively taking care of the low notes, and those low-note 100W are now getting handled by the subwoofer and its amplifier. The speaker then sounds like it is doing 200W, but the 100W on the bottom were via the sub, and when it is blended well… then it seems like the speaker is doing everything… but it is not needing to do it through the full range amplifier, so it seems sweet. Edited May 28 by Holmz 2 Link to comment Share on other sites More sharing options...
olds1959special Posted May 28 Author Share Posted May 28 Some more details: I'm using 6 foot rca cables to the amps from the pre-amp. Also I had to pull back the tweeter control to +1dB. Link to comment Share on other sites More sharing options...
Holmz Posted May 28 Share Posted May 28 38 minutes ago, olds1959special said: Some more details: I'm using 6 foot rca cables to the amps from the pre-amp. Also I had to pull back the tweeter control to +1dB. If you have splinters in there, then the preamp’s supply can be dragged down with more amps, as their input impedance adds together. If it sounds more rolled off with more amp, then the preamp’s output could be getting dragged down If there are multiple 6’ RCAs, then that also makes more capacitance, which would also provide some roll-off, at least in theory... Maybe not much in practice though… 1 Link to comment Share on other sites More sharing options...
olds1959special Posted May 28 Author Share Posted May 28 (edited) 1 minute ago, Holmz said: If you have splinters in there, then the preamp’s supply can be dragged down with more amps, as their input impedance adds together. If it sounds more rolled off with more amp, then the preamp’s output could be getting dragged down If there are multiple 6’ RCAs, then that also makes more capacitance, which would also provide some roll-off, at least in theory... Maybe not much in practice though… The Schiit Saga S active pre-amp has two sets of outputs, making all of this possible without splitters. Edited May 28 by olds1959special Link to comment Share on other sites More sharing options...
Holmz Posted May 28 Share Posted May 28 (edited) ^That may be all true^, but they could also be tied together off of a common (op)amp per channel. I know that it is that way on my preamp, as it was possible to plug the XLR into a piece where the RCAs dropped to a whisper. (It was inadvertently plugged into the wrong place.) But that is also why the output impedance is not zero… so we do not short out and burn up em up… 😇 You could maybe see what it looks like with a cover off, if that doesn’t void a warranty. Edited May 28 by Holmz Link to comment Share on other sites More sharing options...
olds1959special Posted May 28 Author Share Posted May 28 I put the amps on tables behind the speakers. 1 Link to comment Share on other sites More sharing options...
olds1959special Posted May 28 Author Share Posted May 28 I was noticing one pair of amps seems to have a lot more dust inside, and earlier serial numbers. Based on the amount of dust, maybe they weren't recapped, or it was a long time ago. They also say Kenwood on the front (without the Trio) and have the remote trigger switch and inputs. The newer ones don't have these. I switched the bass and midrange / treble cables around and the sound got better. It seems the newer amps have a bit (slightly) more robust sound. Overall, the sound is good and I don't think I need to have the amps checked out, but if one set of amps sounds slightly worse, it makes sense to use them on the bass drivers, right? Link to comment Share on other sites More sharing options...
olds1959special Posted May 28 Author Share Posted May 28 (edited) All four amps have the original NEC high speed outputs. I can see them with a flashlight. All the caps look the same. Edited May 28 by olds1959special Link to comment Share on other sites More sharing options...
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