PrestonTom
-
Posts
4394 -
Joined
-
Last visited
Content Type
Forums
Events
Gallery
Posts posted by PrestonTom
-
-
First thing...make sure you remove the jumpers!
Second, the driver and crossover design will help determine how effective bi-wiring is. The theory behind biwiring is actually sound. Woofers generate back EMF that will modulate the mid/tweeter section. By separating the two sections, you give that back EMF a long path back to the amp where the damping factor helps to resist and minimize any effects. With speaker/amp interactions being so complex, real world improvements may or may not appear.
Measure the resistance of your bi wired path and tell me just how much damping is your speaker wire providing you.
Ah Ha....
A voice of reason!
-Tom
-
Many of us have tried this set up. The results are positive.
A Heresy will work and the results will be quite noticeable. If you like that, then the next step would be horn loaded cabinet (LaScala or Belle). These are preferred since the distortion is comparably low re: your K-Horn. Personally, I use a Cornwall 2 and have been quite happy.
Plenty of threads on the circuit (which can be fairly simple & cheap). You will need an exrta amp. The set up takes a bit of tweaking. The trick is not to turn up the center too much. This set up may also cover up some possible anomalies in the room's acoustics.
Good luck,
-Tom
-
Max,
Thanks for your reviews. I am especially interested in your thoughts on the Cain & Cain's. At one time I was energetic and considering building some single (possibly 2 driver) driver cabinets. There are a number of designs comparable to the C&C Abbeys. Although I am sure these guys have been through a number of headaches getting them right, so I do not want it to sound like it would be a trivial matter. These designs (and I am generalizing) are frequently criticized for their lack of a deep bass (although this is true for many cabinets) and for being able to play at a high volume (since you are asking for a small drived to deliver a great deal of throw). Also there are comments about an "in your face" voicing. However, these comments are second hand since I have not yet had the privelge to hear them myself. However, given these criticisms, the same folks typically have some other very, very positive comments about them. I guess the summaries I have heard are that they are not meant for rock music. I don't condider that to be a show-stopper.
Please tell us more. Some of the home projects of a similar design look like they would be a blast to design & construct.
Good Luck,
Tom
-
DrWho,
Re: the +6 dB gain.
You were a bit quick to reply on that one. No matter if the inputs are attenuated. My analysis (not mine actually since this is standard engineering) is in terms of signal to nose ratio. Obviously one would not want the signal to have a net gain when going thrugh a balanced cable. I was just clarifying that you MUST have the inversion/summation to get a gain in signal to noise ratio. My examples were meant to be helpful in that this exactly what you would expect if you simulated this with a signal generator and 1 or 2 noise generators and looked at the output on a scope/analyzer
In terms of gain in S/N ratio, the two extremes are the cases where the noise is correlated or when it is not correlated.
This is standard stuff and I was confused by why others were confused.
Good Luck,
-Tom
-
Wait, Wait, Wait,
When using a false corner you may want to use some pipe foam along the horizotals to ensure a tight fit into the corner. This, of course, would also be the case for real corners.
Fiber fill and batting are not appropriate in this case. They are designed for other applications (i.e., inside a cabinet for dealing with reflections or more appropriately for making the cabinet "seem" larger by altering the sound velocity).
Your cabinets were not designed to have the sound velocity altered during the final flare nor were they meant to have the waveftont dispersed during the final flare.
By all means use the pipe foam to get a good corner seal.
Good Luck,
-Tom
-
Mark and Shawn,
I understand about not needing a signal on both legs to get the CMRR, but I'm not sure I get the 30db NR in the unbalanced to balanced just by having the twisted pair (like a low Z mic cable) with the rca end tied to the shield. I'm thinking you could tie the one line to the shield on the XLR end and have it be the same, even if electrically they are.
Nice Powerpoint presentation even if it does sell the Jensen products.
Bruce
I agree with Bruce / Marvel (who has been quite correct throughout this entire thread).
If the noise is correlated between the two channels, then the inversion/addition will sum the signals and cancel the noise. The signal-to-noise ratio will be be quite large.
If the noise is uncorrelated between the two channels, the signal will sum (+6db) and the noise will sum (+3dB since it is uncorrelated). In this latter case the improvement will only be +3 dB in terms of signal-to-noise ratio. This latter case, would be unusual and would indicate the limiting noise is perhaps in the electronics and not pickup along the line.
There is no magic here.This is the exact same strategy is also used in transmission of TTL pulses and has been around for sometime.
Good Luck,
-Tom
-
Tommy,
You're right the McIntosh is nice looking, but it is quite expensive.
The first step is certianly to supplement the Heresys with a sub.
I believe the second step is to spend some time and arranging the room and the speaker setup/location. There is no simple formula (although there are some good starting points). It does require some time, tweaking and careful listening. With success, then some room treatment is in order. This can range from fooling with carpet & drapes & furniture to more elaborate treatments such as foam & bass traps. This last step can be expensive so you need to have a clear path in what you like and do not like about the sound. Perhaps prior to this, you might even consider re-freshing you crossovers. If you get caught up in a more extensive upgrading of the crossover you need to be very clear what it is that you like & do not like about the sound (and realistically would a super-duper cross over mod accomplish this)
Next would come the amp & pre-amp since these (compared to the other issues) will contribute the least impact (unless you have a very poor system). It would be hard to recommend McIntosh at this point for driving Heresys. I am not knocking the speakers, but bigger gains (cost wise) would be gained from going the next step up in the speaker chain.
There are a great number of good amps and pre-amps out there that are a better value (where value is determined by BOTH both sound & price).
Good luck,
-Tom -
Robble,
Not to add more headaches to your decision, but.....
Some of the cabinets you are considering have a passive radiator in the back. As such, they would need to moved away from the rear wall. All cabinets are sensitive to room placement but this is a consideration above and beyond.
Good Luck,
-Tom
-
Merkin,
You are asking all the right questions. Please search some of the earlier threads. There has been much discussion on this topic (although some of it is hidden in some vitriolic attacks as I recall).
In terms of conditioners for dealing with transient drops in voltage you are quite correct, a battery will do this. To a certain extent a huge capacitor will do this also. This is what they used in the computer industry where the issues were critical. Not all is lost. Remember the power supplies on your amp etc also have a transformer followed by a large capacitor - this will also help with momnetary drops in voltage from the wall.
Unfortunately, not unlike the voodoo surrounding cables & wire, some have seized upon this as a way of confusing folks ( I am referring to line conditioners not surge protectors - which should be used). Consequently you can pay quite a bit for fancy line conditioners that are dubious regarding their impact on the sound. And as we have all seen before, there are folks out there who will swear to their virtues. Usually the comments will include: "revealing, detailed, opens up the sound" etc.
Save your money. If there is an actual problem, such as a pop or click when the refrigerator or air conditioner comes on, then some remedy may be required.
Forgive my cynical nature. Issues regarding sound reproduction are usually matters of physics, room acoustics and engineering. They are not matters of voodoo. I hate seeing folks waste their time and money on the dumb stuff.
Good Luck,
-Tom
-
Alkemyst,
Sorry about your misfortune
Back to your original question....
As I understand it your cabinets are oiled oak. The ring may have come from water; however, you usually need the dampness to be sustained over a longer period (eg, potted plant). Sometimes, a cleaning solution that contains ammonia might do this (it reacts with the tannins that are natural in oak). Anyhow, short of a great deal of work, there is no simple solution. If you do get advice, make sure it is from someone who has actually done this on a similar finish (do not rely on second hand opinions - " my neighbor knew someone who .....")
Havng said that, the labor intensive option (and it assumes some expereince) is to lightly strip the finsh from the top only (chemically not mechanically). Then very lightly sand the top (very fine-grit) being careful not to round the edges. This is only to smooth the surface since the grain will have been raised from using the stripper. Once it is dry, put a few drops of paint thinner on. The color that you now see will be the color if you simply oil it without any using any pigments in the oil. The match will no be perfect, however, if you only do the top surface your eye is forgiving since the other cabinet surfaces are not parallel and adjacent. Otherwise, you will need to use a pigmented oil. Matching the color requires experiementation. The experiment can be done neatly on the cabinet bottom I assume (this will be hidden anyway).
I recommend Watco danish oil finishes (although the sheen may differ - so only use it on the one surface & do not try to "blend" in the other surfaces).
The common trip ups will be to try and sand the stain away (do not do that) and to treat more than just the single surface (stay confined to the one surface).
There are some who think the Formby products may work. I have not tried them - I do not know. If you do that (and it would be easier, if it works) make sure you hear it from someone who has actually used it to fix a dark ring on a oiled hardwood veneer.
Good Luck,
-Tom
-
JJ,
First of all, enjoy your speakers.
My thoughts: Do not worry about speaker cable. The room you are in is smallish. I believe the biggest effects will come from experimenting with speaker location, placement (you already have gotten a good start) and room treatment.
Next is treating the room and others are giving good advice. However, I will add that part of the treatment can include things like an area rug (or not), or carpet pad (or not), or rearranging furniture, moving your chair away from a rear wall or decorative items on the wall. This is fun thing to tweak. It is best to get some good recordings and listening to them with different configurations. Do this to the point where you have various (revealing) passages fully memorized. You will be listening for the clarirty, imaging, the accuracy in reproduction in various instruments & voices, and whether you hear new things that were formerly hidden in the background. You need to get an accurate description of what aspects are good and which ones need improvement. It gets especially complicated when you then try to communicate this to others.
For the low frequencies, the solutions are more complicated. Certainly bass traps are a viable option. Although pulling the cabinets away (or toward) the rear and side walls should also be tried first. This will not eliminate standing waves but it may shift them either in frequency or location so it is not as bothersome.
As far as the Adcom amp. That is a good unit and can deliver lots of power and current (although this will be less of an issue in your case). These are good first steps (my opinion) and should be exhausted before you start swapping amps (you already have a good one) etc.
Good Luck,
-Tom
-
Please define and give examples of 'well recorded' Hammond B3.
I'm a Jon Lord/ Rick Wakeman fan. Maybe not your cup of tea, Also like Jimmy Smith....
Michael
Michael,
Good question!
I have always been hooked on the Blue Note & Impulse recordings from late 50s through early 70s. Some great music and some excellent engineering. You mentioned the Jimmy Smith - that's a must.
Another one that blew me away recently was a recording by Roland Kirk. I am stumbing trying to remember who was on the Hammond B3 (Ira somethng-or-other). The very first cut, Roland Kirk simultaneously plays a sax and one of his inventions (sort of as a drone). That is the set up. This is followed by the Hammond just cutting loose. Ahhhh, it was wonderful. The only detraction is that on a revealing system, the tape hiss from the original recording can be annoying.
Such is life
Good Luck,
-Tom
-
"That's easy: A well-recorded Hammond B3 organ."
Hmm. That would be a synthesis of a synthesis.
DRBILL
Dr Bill, Quite perceptive!
Normally I would not mention an electronic instrument since part of the reproduction includes the various distortions in the original production. K-Horns certainy shine without any of that.
However, there is something about the tone from the B3 and the vibrato produced by the Leslie cabinet with the spinning horn. I love the sound. As a youth, I spent a good deal of time listening live to a B3 (I was in a garage band).
Last year after doing some room tweaking with my K-Horns, I put on Jimmy Smith (Blue Note or Impulse recordings) and I was "there". I was transported back in time to a garage back in Calif where we practiced ... A wonderful experience. Perhaps this reflects my bias.
Good Luck,
-TOm
-
Just a thought.
Why not use a Cornwall cabinet placed on its side. If you are more adeventurous, then replicate the Cornwall (and place it on the side), but realign the mid and high for a preferred orientation of the horns.
The advantage is that much of the tweaking has already been done for you, courtesy of klipsch. I would suggest using the same drivers, horns, damping material & crossovers. The voicing should be identical (perhaps differing slightly due to altered peaks & dips due to floor bounce & placement of the ports).
If you are trying to get something more akin to a subwoofer incorporated into this, then certainly ignore my comments.
Good luck,
-Tom
-
That's easy: A well-recorded Hammond B3 organ
-Tom
-
Yes, I have a PAS3 driving a Dynaco 120. It is nothing special and also has some hiss and hum that you will hear over efficient speakers.
Honestly, I think you would do a better if you got something else.
Good Luck,
Tom
-
Hello Mike,
Since you seem to like the sound of the Krell, why is it that you are changing?.
The Krell is a very good amplifier. Going to tubes will give a very different sound (a sound that some prefer).
I would suggest visiting a local stereo store that has used/consignment equipment and demo'ing some tube equipment on your speakers first.
Good Luck,
-Tom
-
This is very sad news indeed.
My thoughts and prayers go out to his family and loved ones
-Tom
-
I agree with Bill: It is a shame.
It does not take that much to move from a medicore system to a good sounding one. It takes 1) a goal and a path, 2) a bit of research to sort out the terminology, 3) a bit of experience/listening to enjoy the different aspects of sound that is available, 4) a bit of digging to get a sense of price & value, and 5) some energy on setting up the system and some modest treatment of the room's acoustics.
To graduate from medicore to "pretty good" really requires planning but not necessarily a great deal of money.
Nonsense like this is simply corrupting and distracting. I feel sorry for all the folks who are not able to enjoy the wonderful sound because of all the snake oil salesmen.
My thoughts,
-Tom
-
CAS,
Interesting question. The sound is quite a bit different than a Klipsch.
On the positive side ( and I am generalizing across a number of models). The mids & highs are clear &superb. The imaging can be incredible.
The downside: they need a big amp capable of providing high current. They are difficult to position in a room (lots of tweaking - but is critical for the imaging and clarity). The bass can be weak. They do not always sound great (dynamic) when played loud (varies across models). These last two problems are magnified if the amp is not adequate.
In spite of this I keep a pair of Maggies & Marti-Logans around the house. The do very well on small ensemble classical music, esp choral, baroque and early music. Some day I will get rid of them, but I have been saying that for a few years now.
Good Luck,
-Tom
-
Cultrain,
Go slow on this.
First, please do not assume that the fuse is reliable and will always blow quickly enough to protect the speaker.
I think it is irresponsible for anyone to suggest keeping the K-Horn (esp with the drivers hooked up) in the circuit while you do your initial trouble shooting. Substitute a cheap speaker or a 10ohm 10watt power resistor ($1 at radio shack). Be systematic. Start at the amp and then work your way to up crossover (which is probably not the problem unless a wire/lead got loose). By no means leave the the K-Horn in the circuit for the initial testing!
Good luck,
-Tom
-
HF,
Welcome to the journey. You commented that there was a perceived "bias" toward the Cornwalls. Well they are a good speaker, however.......... In my humble opinion the K-Horns are something special.
Yes, there is a difference in price and the placement issues are critical for the K-Horns (although careful placement is important for all speakers).
Take your time to find the the right deal. I was able to get my K-Horns for about $1000 used. This is about half of what they usually retail for (edit: I mean that used ones sell for). The price is mostly determined by finish & condition (model year to a much lesser extent). However, once you get away from e-Bay and instead scour local shops & classifieds you can find a deal (in part because they are so difficult to transport).
The Cornwalls are typically around $600-800. Again, a deal can be found. In fact, thanks to a forum member I was able to get a pair of oiled oak CW 2's for $400 (I am still happy about this one).
If you are patient, have the money, have the corners, then a K-Horn is the ticket. Otherwise, Cornwalls can also sound very nice.
I am not objective, my opinion is very biased - hold out for the K-Horns.....
Good Luck,
-Tom
-
JJ,
Congratulations on re-viving your Klipsh system!
Dragonfyr has made some good points, think about them. You are absolutely correct in addressing the room issues first. Placement and room treatment (even if it's informal stuff like drapes, carpets & furniture) will have a far greater impact than components (Adcom is nothing to sneeze at) and cables (probably no impact anyway).
The on-axis response is probably the the flatest, so do not worry too much about toeing the cabinets inward. Beside this will also swing the ratio of reveberant vs direct sound back toward the direct path. Depending on the room geometry, try systematically varying the distances from the rear & side walls. Use a CD that is well-recorded and that you are quite familar with. Go ahead and experiment and tweak. It is well worth the effort.
Good Luck,
-Tom
-
Jeff,
My suggestion is that you first check e-bay under completed listings to get an idea what the NAD has actually been selling for.
Sending the unit to get serviced can be expensive. The expense can sometimes catch people by surprise.
Good Luck,
-Tom
Balanced inputs vs rca
in Technical/Restorations
Posted
I really do not understand why there has been so much confusion throughout this thread.
Lets look at it very simply, because it really is simple.
I can sendsplit a signal in two and send it down a cable (one inverted in phase relative to the other). While the signal(s) is travelling down the cable it picks up noise. The noise for the most part is correlated / identical between the two wires. When the signal(s) have reached of the cable and they have picked up some noise - what to do. Well I can invert the signal (plus noise) on one side (that was originally inverted anyway) and add the the two wires together.
Presto!
The signals are back in phase and add up by +6dB (& yes, you may have attenuated them by -3 dB to begin with so there is no net gain). What about the noise that was picked up by the cable. Since the noise was common/correlated between the two channels, You have effectively subtacted the noise (inverted the phase & then followed this by a summation).
Good news. Between the two wires, the signals add and the noise cancels. Now you have a very large signal-to noise ratio.
Now for the other extreme. What if the noise was uncorrelated between the two wires (vey unlikely in this configuration) then the signals are correlated so the summation for the signal is +6dB. However the noises are uncorrelated so the summation is only +3dB. Net gain: an increase in signal-to-noise ratio of +3dB.
So between these two limiting cases, the signal-to-noise ratio has either increased by a VERY large amount or in the other (less likely case) it has increased by +3dB.
Why is there this red-herring about impedance.
The phase inversion will not change the impedance. However for this trick to work the signal at each wire(one inverted in phase relative to the other) must be equal. Why not ensure this by sending the signals to a transformer on the other end. Now the sender only "sees" the transformer. So whatever else happens in the circuit downstream is effectively isolated and the signals being sent are "equal" between the two wires.
Now when you have low level / high impedance signals, such as phono or a microphone (the more typical example) you can now send it great distances and although you will pick up a bunch of noise, it can then be cancelled. So splitting the signal, then inverting one leg then sending them down the cable (and picking up some noise), then re-inverting the one leg and then summing (adding the signal and subtracting the noise) does in fact work.
Is this important in audio applications where you have line levels sources (CD, DAT, tape or tuner)? There it is probably not an issue. Does it matter when you have a phono source going a short distance (with decently shielded cable)? Again it is probably not an issue.
Does it matter in a professional rig and going great distances or when your "source" is a microphone? Yes! It is an absolute must.
As I said before, this is a standard & straight forward engineering issue/solution. This is not just an audio trick. It is also used in data communications with TTL pulses etc.
Good Luck,
-Tom