Adding Tone Controls?

Bvdiman, Normally I would agree with your sentiments. In fact in my first post I completely avoided comments of any type on other possible contributions to the problems he was experiencing and a couple of possible solutions. None what so ever. As I said, he had good stuff and said he didn't want to change the sound of his system and I thought 'nuf said.

However since that post, he has recieved all sorts of recommendations, some fleshed out, some not. For example, the toe in recommendation. Now toe in with electrostats/panel speakers can be a huge issue because of the back wave, a problem distinctly different from toe in with boxes. Box speakers have a broad dispersion pattern vs the narrow dispersion pattern (think fan shape v a typically figure 8 shaped) of panels & electrostats. I looked at his set up and his speaker placement was very typical for boxed speakers, not necessarily for panels or electrostats, obviously IMHO. I learned that the hard way - no one told me. It was free advise that someone might just find useful, and it costs nothing to implement. Then why not? I saw no reason to assume he would be offended.

Ditto, Nordost cabling. It has a particular reputation in the market regarding its sound that differentiates it from a lot of other cable. Was Bama aware? If so, no harm. If not, well it gives him something to think about.

His post on 11/28 was somewhat interesting I thought. On the one hand he thought suggestions by myself and others, to put some type of an equalizer in the tape loop were very good ones, yet he neither closed the correspondence nor sought further guidance in an area with limited potential for resolution beyond that done. He just complained about the rec's that were beyond his original request. Complaining about free advise is always curious to me.

This suggested to me that perhaps, even against his comments to the contrary, that fleshed out recommendations might cause him to re-think his problems and potential solutions. I thought I'd take a try at spelling it out a bit. If he already knows - OK. If he doesn't know, he learns. What's at risk, his ego? Why would/should we think that? I work on the assumption that only your friends tell you your fly is open. Others like to just stand back and giggle.

Why do I take the time to write two posts and even explain myself to you? It is because I am (and I would like to say we are) trying to help him improve his sound, even if we have to go beyond his request. That is what most of us would want if we were in the posters position. Pride disappearing in the face of constructive critism or honest observations is not an attribute I normally ascribe to folks who need help, validation perhaps. After all, at the worst we are all a bunch of assholes and he'll never correspond with us again, or perhaps he had a hole in his knowledge base that we have helped him fill.

Whatever....It is free after all.

Again, thanks for all the responses. In answer to a few of the comments, let me offer the following:

.... Youthful, high acuity hearing does not appear to be the issue - I'm a proud member of the boomer generation. My hearing still tests well, but not like it was back in my 20s.

.... Impedence issues between the CJ preamp and Pass amp were (and maybe still are) a concern. I raised this issue a while back on another forum and received feedback from several folks (including Kal Rubinson) confirming that the pairing meets the guideline that "the input impedance should exceed the output impedance of its source by 10x or more".

.... The photo of my system in my profile is obsolete, since we've moved to a new home. The new arrangement is similar, in that a group of windows (with some drapery panels) lies behind the speakers. The room is dedicated to the audio system however, so I do have as much flexibility as needed to try acoustic treatments. Rough dimensions are 14 ft wide by 32 ft long, with the speakers firing down the long dimension. Speakers are roughly 7.5 ft apart (center to center) and about 5.5 ft from front wall (to speaker front side). The listening position is about 13.5 ft from the speaker front. Slight toe-in (to cross behind the listening position). For what it was worth, I used a sound pressure meter in an attempt to position the listening position away from any obvious low frequency nodes.

.... Previous cables were Purist Audio Elementa. To my ears, the Nordost was an improvement in speed and clarity.

.... In a previous system, I used a hybrid tube/solid state ARC preamp (LS2), with a solid state ARC amp (D200) and dynamic speakers (Theil 2 2s). It seemed to be a good system at the time, but I'd say that crummy recordings still sounded crummy. The current system beats the previous one in air and clarity on good recordings but, sadly, still sounds crummy on the others.

I appreciate the added info on the DSPeaker Dual Core. I'll do more research on it. Christmas is coming!

Lastly, I'm appreciative of all suggestions. I was merely trying to focus the conversation. Perhaps the added info in this post provides more background.

Impedence issues between the CJ preamp and Pass amp were (and maybe still are) a concern. I raised this issue a while back on another forum and received feedback from several folks (including Kal Rubinson) confirming that the pairing meets the guideline that "the input impedance should exceed the output impedance of its source by 10x or more".

Like you, I am uncertain. The 10x factor should be applied to the worst case (maximum) output impedance of the preamp at any audible frequency. For a tube preamp that will commonly be at 20 Hz, due to the output coupling capacitor most (but not all) tube preamps use. Per Stereophile's measurements the original version of the C-J 16LS had a worst case output impedance (at 20 Hz) of 1.8K, and from their comments in the addendum to the review it sounds like the upgrades that were incorporated in the Series 2 version would not have affected that. The manual for your X250 indicates that the input impedance of its balanced inputs is 22K, while not indicating an input impedance for the unbalanced inputs which I presume are provided and you are using. Conceivably the unbalanced input impedance could be half the value of the balanced input, or 11K, which would result in a SLIGHT rolloff of the deepest bass when driven by an output impedance that rises to 1.8K at 20 Hz, while having significantly lower values at higher frequencies.

Re the use of digital equalizers: I did some further checking, and it appears that the two digital outputs of your transport are both 75 ohm coaxial outputs, on an RCA connector and a BNC connector. It also appears that neither the Behringer DEQ2496 or the DSPeaker will accept coaxial digital inputs. Also, the DEQ2496 does not provide unbalanced analog inputs or outputs, so it could not be inserted into a processor/tape loop on your preamp without converting or adapting the signals from unbalanced to balanced form, and back, which would introduce additional cost and/or possible sonic compromise depending on how it is implemented.

The DSPeaker device provides unbalanced analog i/o's, as I and others indicated earlier, and could be readily introduced into one of the processor/tape loops that is provided on your preamp. The one possible issue I see with respect to that approach is that the output impedance of the preamp's processor/tape outputs is not specified, and the input impedance of the DSPeaker's analog inputs appears not to be specified. You might want to contact the two manufacturers to ask them if they can supply those numbers. Although given that the DSPeaker would only be in the signal path when you are listening to the problematic low quality recordings, a less than ideal impedance match may not matter anyway.

Finally, in case you want to consider other kinds of digital equalizers, which could accept the signal from one of the transport's coaxial outputs, I would be cautious about assuming that both outputs can be used simultaneously, unless the manual or other literature explicitly indicates that they can be. It seems conceivable to me that the RCA and BNC connectors might simply be jumpered together inside the rear panel of the transport (rather than being driven by separate output stages), the expectation being that only one of them would be used. In that situation, using both at once would result in a severe impedance mismatch, which would undoubtedly degrade sonics for both outputs.

Hope that helps. Regards,
-- Al

Bama, Nice post. A couple of comments on speaker/listening chair location/set up. Keep an open mind on this because some of it is not intuitive and conrtary to customary set up.

1) Set the speakers up so that the speakers/listening chair form an equallateral triangle. In a room with you room's dimensions I would keep the distance from the back wall at 5'+, but I would seperate the speakers substantially more apart. Say 10' with the listening chair back to about 10 - 11'. This will give you a much larger soundstage and, in my experience contribute to reducing congestion which is not unusual when the speakers are too close together and listened for far back.

This will also place the speakers closer to the side walls but due to the nature of those speaker's radiation pattern side wall reflections are not a big issue (remember figure 8 pattern). The only thing it might affect is the bass response linearity a bit, maybe a little boost between 100 and 200 hz. But then all speaker position will do that Often its a matter of choice of options, not perfection.

2)I would toe the speakers in so the axis of the speakers pointed at the listening chair and the back wave bounced off the side wall behind them. This will reduce the need for acoustic treatment on the wall behind the speakers substantially and quite possibly bring the stereo image into greater focus.

This is going to look and sound different than your present set up substantially I think. It will also require some tweaking after initial set up so give it a chance. If it works it will save you money and grief and perhaps as I suspect enhance your listening experience. If not just put them back to where you have set them now. Invest a couple of weeks (at least in this project). I discovered all of this the hard way and it took me an embarrasing long time :-)

BTW, flat bass response set with meter or by ear is going to be impossible, close perhaps. But I do not let flat bass response dictate where I set my speakers unless it is gross. It's the mid's and highs that are essential. Usually the location of the listening chair is as, if not more, important for getting a good bass response anyway.

OK, I'm done. Sorry for the length of my posts. Good luck and let us know how it works out for you.

To add to Almarg's always helpful post above--About the DSPeaker--it looks like you can special order input impedance to whatever value you like for slight up charge (not specified). Standard is 10k ohm. I have been kicking the tires on that unit and looked at the owners manual yesterday. Hope this is helpful.