Phono Stage upgrade to complement Dohmann Helix One Mk 2

Holmz, the first two of your last 3 bullet points would result in bypassing the main amplifier.

Hmmm. . .I’m back to the consideration stage: apparently, the most neutral approach to add a HPF in my current system is via a high-grade capacitor. However, these capacitors only give a 6 db / octave adjustment, which means starting at 80 Hz (so that the mid-range isn’t affected), would only drop the volume by 6 db at 40 Hz, which is the lowest sound played by the cello, although the piano may drop to 30 Hz on occasion, which would give about a 9 db decrease in signal to the main ESL speakers.

To put things in perspective, one click on the volume knob on my pre-amplifier is about 2 db (and it is usually set around 26 clicks) so we’re talking dropping the volume only 3 clicks for most low frequencies, and at most 4 clicks for the lowest, which is only going to be about a 10-20% drop in volume for these frequencies.  So I’m not sure a standard analog capacitor HPF is going to make much of a difference in attenuating the signal to the main ESL’s; and apparently, the built in HPF in subwoofers are also the standard 6db / octave. Ideally, I would get a high quality analog HPF, which would minimally affect the SQ, and filter at 24 db / octave. . .but that may be like the tooth fairy: impossible!

@holmz , Not at all. You ever tried an analog crossover on ESLs? Wel I have, several ones and they all turned out to be awful in the end. You can do it but there are far superior ways.

@drbond , 6 dB/oct is no where near fast enough to get the drop in distortion and increased head room I have been talking about. My filters are currently 48 dB/oct and the only way you can do that in an invisible fashion is with digital crossovers. I have been through every permutation of this problem some several times and have lost a lot of hair over it. If you do not want to use anything digital in your system you are better off without subwoofers otherwise they will drive you nuts and you will have wasted a lot of money. Subwoofers have to disappear into the music. You should not know they are there until a very low note comes along. In order to get the benefits of lower distortion and increased headroom, critical for ESLs you have to cross over in the area of 100 Hz which makes life even more difficult. Subwoofers also have to be placed in specific locations in order to work well. They are over 6 dB more efficient against walls and even more in corners. You also eliminate some (but not all) of the room interaction this way. This places them three to 5 feet behind the ESLs. In order to get the speakers aligned in time the ESLs have to be delayed a little. You can only do this in the digital domaine. Any other approach is a compromise you are not going to like. 

@lewm , all my filters are digital. I can select any slope and any frequency at 1 Hz intervals and I can make adjustments on the fly from the listening position. This is TOTALLY different than analog filters. 

@rauliruegas , I have heard you say on multiple occasions that digital reproduction is not just a little, but far more accurate than analog. Have you changed your position? I have owned Velodyne Subs and have listen to some of the more current models. I would never have one in my system. There are many great woofer drivers out there now. The differences in the good ones are relatively minor in comparison to the differences in enclosures. There is not one commercial subwoofer I would have in my system, not one. Not even the Magicos (to effin big!). But in order to have a chance at being uncolored the sub has to have two drivers at opposite ends of the enclosure operating in phase. This keeps the sub from shaking at volume which causes distortion. The only commercial subs that do this are the Magico Q Series, Some of the KEFs and the ML BalancedForce series. The best way to avoid driver distortion is to use large ones of high quality. The amps used in any of these subwoofers are compromised because they can not produce significant amounts of heat. They also have to fit within the subs and the manufactures want to keep them small. IMHO passive subwoofers with outboard electronics are the only way to go. I double darn guarantee that not one subwoofer plate amplifier can produce the bass of a JC1. Unfortunately, this is a much more expensive approach but that is life. 

Now as for as my turntable is concerned. If I remember correctly your most significant concern with phono stages is an accurate RIAA correction. My phono stage is connected to a Lynx Hilo, a studio ADC, DAC router. The phono stages output is set to flat (no RIAA correction) and the correction is performed by a program in my audio computer. It is way more accurate than anything you can do in the analog domain, very cool. You should try it or are you going to be one of those stuffy analog only guys. Good luck trying to find an analog record now a days.

Mijo, my question was specifically what are you using to provide digital domain filtering, that is, what brand and model? Thanks.

Here on Audiogon and elsewhere there are always a plethora of good high power solid state amplifiers for sale pre-owned at prices far below the cost of a new JC1. You’ll say the JC1 is best and I’ll say we’re only talking about the lowest 2 octaves of low bass. I’d look for a Threshold or Krell or any of many other good choices. In fact one might find a used JC1. I do also like the force cancellation idea.