No.4 Posted June 20, 2015 Share Posted June 20, 2015 Ok. LDRs get good reviews. Not really a passive pre though. They require a power supply and all issues associated. A "passive" pre is just a potentiometer or attenuator in between the source and the amp. Simple. Two resistors in my case. Quote Link to comment Share on other sites More sharing options...
Shakeydeal Posted June 20, 2015 Share Posted June 20, 2015 (edited) It is exactly a passive. The PS is not in the signal path, only used to power the LEDs. There is only the unity gain provided by your source component. You would only need to hear it to believe how much better it is. Shakey Edited June 20, 2015 by Shakeydeal Quote Link to comment Share on other sites More sharing options...
tube fanatic Posted June 20, 2015 Share Posted June 20, 2015 There's really nothing wrong with a resistor based passive attenuator. Remember that a LDR is a high resistance semiconductor device which will pass more electrons in response to light intensity, so whether it is better sonically than a high quality film resistor is difficult to quantify. The passive unit I showed above uses a single resistor to couple the source to the input of the equipment with the pot simply acting as a signal shunt to ground. It would be interesting to try a level matched blind listening test between a good resistive attenuator and a LDR to determine if a listener could consistently discern a difference.Maynard 1 Quote Link to comment Share on other sites More sharing options...
PrestonTom Posted June 20, 2015 Share Posted June 20, 2015 (edited) This discussion has gone all over the place. Passive pre-amps are either resistor based (LDRs, potentiometers, or restor dividers in a multi-stepped switch). The alternative is a transformer based unit which can be rather pricey. This strategy does not always work well. Whether it works is not a function of magic or exotic parts. Rather it is a function of load impedance and source impedance, source's voltage output, amplifiers sensitivity and whether the cabling is low capacitance (I did NOT say "fancy" cables). It is also a function of your listening habits (how loud). Unfortunately, there is a good deal of marketing on these products and the price mark ups can be extraordinary. Most users are not willing to look up the input and output Z of their equipment or to calculate how much gain their system needs, etc. This leaves the consumer having to try a passive and see if it works out or not. I would not rely on someone else's opinion of a passive solution since their experience is highly dependent on what other equipment they had in their own system. It really can be an issue of system integration and not picking an individual part without regard to the what else is in the chain. At the very least get a project box and swap in a stereo pot. Without knowing anything about your system, try a few different ones (10 k to 50 k). Use some alpha pots since they are cheap. If the results are miserable, then give up. If there is some merit, then do the homework and try some better parts. It really can be a simple project. There is no reason to dive in head first and pay hundreds of dollars just to find out that a passive will not easily integrate into your system. Edited June 20, 2015 by PrestonTom 1 Quote Link to comment Share on other sites More sharing options...
Shakeydeal Posted June 20, 2015 Share Posted June 20, 2015 For me the proof is in the listening. Passive devices aren't for everyone, and some systems need the extra gain. I owned three TVC based passives and one using autoformers. All were good and better than active preamps I have owned up to 8K. The LDR was the first preamp that made me consider selling my Sonic Euphoria autoformer passive. Every active preamp I have owned, as good as some were, colored the sound to varying degrees. If that coloration suits you and enhances your listening pleasure, then good for you. Now the two passives that I tried and didn't like were the Reference Line Preeminence One and the Placette. The former was transparent, but rolled off and muted the dynamics of the music. The latter was transparent and dynamic, but thin and lackng body and presence. The bottom line is to buy and use what suits your ears. System matching is very crucial when it comes to a passive, more so than with other preamps. Shakey 1 Quote Link to comment Share on other sites More sharing options...
No.4 Posted June 20, 2015 Share Posted June 20, 2015 Shakey, which LDR are you using? Quote Link to comment Share on other sites More sharing options...
The Dude Posted June 20, 2015 Author Share Posted June 20, 2015 At the very least get a project box and swap in a stereo pot. Without knowing anything about your system, try a few different ones (10 k to 50 k). Use some alpha pots since they are cheap. If the results are miserable, then give up. If there is some merit, then do the homework and try some better parts. It really can be a simple project. There is no reason to dive in head first and pay hundreds of dollars just to find out that a passive will not easily integrate into your system. I really appreciate this statement on the matter and Maynards design is simple enough that allows someone to do just that. I have a alps pot, and a selector switch so I could easily do this. At this point time there isn't much time for me to play that much. So I think if I really wanted to try one, I would try the SYS from Schiit for $48.00. Every active preamp I have owned, as good as some were, colored the sound to varying degrees Thats the other reason I came to ask the question. I don't know if it was the preamp I was using, or bad eq settings on my horn. But things sounded colored is how I would put it. Since I have gone direct from the PC to the active, things are sounding pretty good. If I decided to try a passive unit, it would mainly be for switching sources. Quote Link to comment Share on other sites More sharing options...
TJIann Posted June 20, 2015 Share Posted June 20, 2015 (edited) If I was to only use my computer that has a volume control, could I get away without having to use anything and just hook directly up to the active crossoverYes, assuming the voltage output of your sound card is adequate. It can't hurt to give it a try.Maynard Yes it seems to work fine. Tonight I will be playing with the system and see what happens. If the weird pops go away I will know it is in the pre amp. For now I am only playing music from my computer. When I go to add another source I will need to do something for source selection. Oppo 103 or 105 player... They have dual HDMI inputs. You can then run from the Oppo via analog out to a passive preamp. Technically, do you even need the preamp after the Oppo? The DACs are good, it has a volume control, so could just use the analog out to the amp(s), no? Edited June 20, 2015 by TJIann 1 Quote Link to comment Share on other sites More sharing options...
Shakeydeal Posted June 20, 2015 Share Posted June 20, 2015 Shakey, which LDR are you using? It is made by Abacus Music in Charlotte, NC. It uses the Tortuga Audio LDR 3x v2 board . http://www.tortugaaudio.com/products/ldr3x-passive-preamp-controller-version-2/ Quote Link to comment Share on other sites More sharing options...
mike stehr Posted June 20, 2015 Share Posted June 20, 2015 The PS is not in the signal path, only used to power the LEDs. Quieter Power Supply: Version 2 replaces a linear voltage regulator with a precision low noise switching power supply module with superior ripple rejection. The result is a darker background between the notes and improved articulation and expression of sound. What does this mean? It now sounds even better! 1 Quote Link to comment Share on other sites More sharing options...
NBPK402 Posted June 20, 2015 Share Posted June 20, 2015 If I was to only use my computer that has a volume control, could I get away without having to use anything and just hook directly up to the active crossoverYes, assuming the voltage output of your sound card is adequate. It can't hurt to give it a try.Maynard Yes it seems to work fine. Tonight I will be playing with the system and see what happens. If the weird pops go away I will know it is in the pre amp. For now I am only playing music from my computer. When I go to add another source I will need to do something for source selection. Oppo 103 or 105 player... They have dual HDMI inputs. You can then run from the Oppo via analog out to a passive preamp. Technically, do you even need the preamp after the Oppo? The DACs are good, it has a volume control, so could just use the analog out to the amp(s), no? I would say no...but it would depend on whether or not the Oppo has enough umph to drive your amps. Quote Link to comment Share on other sites More sharing options...
Wardsweb Posted July 3, 2015 Share Posted July 3, 2015 I replaced my McIntosh C36 with a Sonic Euphoria that uses autoformers. I have high efficiency horns and 22 watt SET amps, so I didn't need any gain. I tried some Promethius TVC but the Sonic Euphoria was more open and detailed. 1 Quote Link to comment Share on other sites More sharing options...
The Dude Posted July 3, 2015 Author Share Posted July 3, 2015 Ward, thanks for sharing your recommendations you all ways have some top notch gear. wdecho, I have read quite a bit about Mr. Pass. At one point I had all minus the passive components to build 3 F5TV2. But never got around to it, and sold the parts. I will take a look at the buffer. I am always looking for a small project(like I need one like I need an extra hole in my head). Thanks for pointing out, this great idea. Quote Link to comment Share on other sites More sharing options...
Guest thesloth Posted July 3, 2015 Share Posted July 3, 2015 (edited) Anyone who says a resistor based passive pre sounds bad really probably wasn't using them correctly. They were either using them with long/high capacitance cables or incorrectly loading one of the devices. For one, in your CD player there are probably hundreds of resistors in the signal path, then there is the power amp, again lots of resistors in the signal path. I think for the majority of people it's psychological, a pre with gain you turn the volume up much less. Then they switch to passive and have to turn the knob up much more then usual. +1 on buffers! When in doubt or if long cables are being used, or those hard to drive 10k input power amps a buffer is usually all you need with todays sources putting out 1-2Vrms. Edited July 3, 2015 by thesloth 1 Quote Link to comment Share on other sites More sharing options...
justinsweber Posted July 7, 2015 Share Posted July 7, 2015 https://m.youtube.com/watch?v=yUIrKOldEp0&sns=fb Quote Link to comment Share on other sites More sharing options...
Guest thesloth Posted July 7, 2015 Share Posted July 7, 2015 That video was painful to watch. Seriously? He states that resistors "suck at conducting music" at around 2:45. Obviously the video is some really terrible propaganda to get the misinformed's money. What an idiot. Quote Link to comment Share on other sites More sharing options...
justinsweber Posted July 7, 2015 Share Posted July 7, 2015 New Record day's reviews have their audience. That'd said the pre he reviewed seems pretty interesting and within reach. Quote Link to comment Share on other sites More sharing options...
Guest thesloth Posted July 7, 2015 Share Posted July 7, 2015 I did notice that he is using your Casablanca amps for the review, nice plug Anyway I don't see what he is trying to achieve in the review. He states that his phono pre is set to a gain of 66db and his cartridge's output is .3mV. So he is only driving your amp with around 1V which your website clearly states that to achieve full power you need 1.6V. For some reason he thinks swapping speakers will change this fact. Actually on second thought it's just another way for him to plug gear and line his pocket with money. If I were the speaker manufacturers I would be kind of ticked because he is making it look like the speakers are not up to the task, and even your amp. Most people know 50 watts is plenty but this guy isn't getting 50 watts from your amp because he isn't driving it correctly. Again, what an idiot. Quote Link to comment Share on other sites More sharing options...
justinsweber Posted July 7, 2015 Share Posted July 7, 2015 That's no secrete. The actually review is coming. Many on here run my amps as they also run others who build. No one really plugs but share what we're trying. Again, I was focusing on the LDR. Which can be a wholly awesome option for anyone wanting to go passive. ( I like that it uses a remote). Quote Link to comment Share on other sites More sharing options...
Guest thesloth Posted July 7, 2015 Share Posted July 7, 2015 There are different ways to skin a cat and options are good. I just feel there is a lot of misinformation from that video and too much snake oil mumbo jumbo. I am sure the preamp works just fine, but if you are going to say that a product is superior don't just give subjective reviews as testimony, a little actual real world data would be nice. He pretty much contradicts himself in the 6moons review. He asks why spend all this money on a preamp when you don't need any gain, but he wants you to pay $1200 for something that doesn't even give you the option of gain lol! What a scam. I get it, if you want to do something differently that is more than fine. If people want to spend a ton of money to be different so be it. But don't claim it's better then things that it's not. Quote Link to comment Share on other sites More sharing options...
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