Balanced Passive Pre Amp
tmac1700 For under $200 This one looks to be very good build and circuit quality, relay based switched resistor, (better than potentiometers, even Alps) And it has a linear supply no rf from smp, and you may hear a little clicking only when turning the volume up and down). https://www.ebay.com/itm/162637265690?hash=item25ddefbb1a:g:qX8AAOSwq3he16uO Cheers George |
If you're willing to go above $200 to get something higher-quality, the one I'd recommend first is the Goldpoint SA1X, which is a very basic but uses precision-matched stepped attenuators. Another option is the Khozmo Passive Preamplifier. |
OP I bought 3 different passives from 49 to 149 dollars. Three years ago. All three had good traces on the board and ZERO problems with noisy volume control pots... Mine were all copper traces inside. They should be inexpensive. It took me a whole 3 hours to build one from scratch.. and 2 hours for the second one. I added a dirt cheap BASS XO circuit to one also for a additional 10.00 or so.. I just left the onboard passive XO (for the bass) out of the loop and direct coupled the amp to the bass drivers.. It worked perfect for the application.. XLR in or out with an option to go single ended (RCA ) if you wanted.. In or out.. That one was 59.00. I think it was Nobound. I couldn't find one that wasn't made in China under 300.00 anywhere.. Maybe you'll have better luck.. if that is an issue. Wasn't for me.. |
I own both the Khozmo and Goldpoint units discussed previously here and IMO, the Takeman REY metal film and Vishay Z-foil resistors used in my Khozmo passive sound better than the slightly dryer sounding SMD resistors used in the Goldpoint unit. Both units are very clear and detailed sounding. The balanced Khozmo model with only one input (and two outputs) is $379 (Caddock resistors) and you can add remote control for $200. I know this is more than you want to spend but IMO it would give you a more flexible, and better sounding, solution as well as remote control if you want it. For $20 more you can have a pair of inputs. I use mine (dual mono version with remote and display) in a moderately high end system and do not believe it is a limiting factor. Of course, both the Khozmo and Goldpoint units are occasionally listed for sale used on this site or other sites at about 50-70% of the original list price. Otherwise, you might try this for $235 - balanced, remote, display, and relay volume control (but I have no idea about the performance). |
If you pay 5,000 dollars, you can get such a self-made machine. https://page.auctions.yahoo.co.jp/jp/auction/335310604 Perfect full balance (600Ω: 600Ω). It is equipped with four ancient daven attenuators. |
Hello tmac1700. You need the output of the preamp to be balanced, right? Not the inputs, right? Does your DAC have RCA phono plug outputs? If not, you may have to revert to adapters. You could add transformers to the output of the passive preamp. There's probably room in the box because there isn't much to a passive preamp. Any decent tech could do the job. Something like 10k to 50K primary and balanced output, 500 ohms to 2Kohms center tapped. Jensen will have something like that. You will lose a lot of voltage though. If you need balanced inputs on the passive preamp, that could be a real problem. Think about a good used preamp with balanced ins and outs. Good Luck! |
I use these attenuators from EVS and I recommend them highly. Can you access the back of the speaker easily? If so perhaps you could plug in directly to the speaker eliminating one pair of interconnects. I am using mine between a balanced DAC and a balanced amp (both Benchmark). http://tweakaudio.com/EVS-2/custom_modsultimate_attenuators.html These are more expensive but there are probably less expensive options as they are made to suit each client. |
