PrestonTom
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Posts posted by PrestonTom
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It is important to pay attentuation to what Marvel said.
The cable from the pre-amp to amp will have a small amount of capacitance (especially if it is not short). Changing the resistance by swapping the pot or adding resistors MIGHT inadvertently produce a low-pass filter (single pole with a corner at 1 / 2*pi*R*C). The output impedance of the pre-amp and input impedance of the amp are not arbitrary.
Good luck,
-Tom
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The old advice is still true: The speakers will make the biggest difference. The CD player will make the least difference. The "misc" (speaker wire etc) will make no difference. The amp is tricky. If it is large enough (depends on whether the speakers are efficient and do not require much current - i.e., not low impedance) then most solid state amps will sound fine (if it adequately sized and it is quiet). Tube amps will have a different sound - some folks prefer that sound.
For loud music in a large room, then choice of amp may be trickier to find one that is adequately powerful (unless the speakers are an easy load). Note, this not simply a matter of Watts - there are also issues of headroom and being able to provide adequate levels of current (again depending on choice of speaker, listening preferences and room size).
Focus on the speakers! Then the effort should be spent on setup (this is not always expensive). They should positioned carefully (and this can take quite a bit of experiementation - but the effects are real). After this spend your energy on treating the room. Invest some time in learning about "room acoustics 101" and then tackle the listening room. Issues at mid and high frequencies are more easily taken care of (carpets, drapes, carpet padding, furniture set up etc). Issues at lower fequencies are more difficult and may cost a modest amount of money (but please educate yourself first).
These are not "sexy" solutions, and others will disagree. However the effects are real. Small changes in speaker location and room set up will yield very noticeable changes in sound. The trick is determining whether the changes are for the better - it does take tweaking and experimentation, and most importantly, some time spent educating yourself about room acoustics.
Good luck,
-Tom
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Re: Using a "passive" pre-amp with a ss amp.
I have bee doing this configuration with an Adcom straight line controller (passive pre-amp). One thing that is sometimes missed is that the output impedance of the passive preamp is not as high as a typical pre-amp.
One consequence is that a long interconnect from the pre-amp to the amp, can acually introuduce some low pass filtering, since the input of the amp is typically configured to "see" a higher impedance input (this is a folksy explaination) from the pre-amp.
The corner freq of the this "filter" would simply be a one pole filter (6 dB per octave) located at
1 / (2*pi*R*C). In this case the capacitance would come from length of the cable. This is generally very small (and typically ignored) and it is specificed as capacitance per length of cable. It is best to use a cable shorter than 2 ft. This is a real effect and not "cable voodoo".
I am not advocating using some expensive & esoteric cable. A typical interconnect, if it were 3ft long, might actually low pass the signal at 13-14 kHz. The solution is simple, make sure your cable from the passive pre-amp to the amp is short.
Good luck,
-Tom
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Gee, those were two absolute giants!
I bounce back & forth on listening to those old recordings. The music is incredible but the sound is sometimes problematic ( I know, it's about the music). Some of these recordings have been cleaned up pretty well and that helps. Actually, after listening fo a couple of hours, you seem to adapt a bit. Maybe some day I will pick up a used DBX or Carver AUTOCORREALTOR. Those devices helped as I recall, but I am shy about ading extra pieces in the circuit.
Wait, it is about the music ....
Good Luck ,
Tom
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Danny, Congratulations!
I enjoyed hearing your story. Those K-Horns look absolutely fantastic.
Good luck,
-Tom
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Jeremy, keep up the upbeat mood. There is an end in sight!
I have a silmilar problem. My listening room is next to my kichen. The kitchen is undergoing a rennovation and many supplies etc are now in the listening room (which is aslo covered in dust, regardless of the various precautions). With boxes and tools piled everywhere I have not been able to listen to my K-Horns in the last 3 weeks. The kitchen re-model started out as: "why not build a center island" and morphed into tearing out all the cabinets, new underlayment/ceramic tile floor, upgrade on electrical and some plumbing, paint, trim etc (it is 450 sq ft - so all the headaches and expenses are multiplied upwards).
It is going to look good when it is done....that has become my mantra. Thank you for letting me commiserate.
Good luck,
-Tom
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This issue of the "loudness" knob comes up periodically. And when one looks at the logic of it, in fact it does not make sense given a certain assumption.
Stereo reproduction at a low level will (and should not) not have much perceived bass. Live music at a low level (perhaps at a great distance etc) will also not have much preceived bass. The assumption (and one that I subscribe to) is that the the goal of the reproduction is accuracy. In simple words, does it sound like the real thing or can I close my eyes and get a sense of "being there". There is no "volume" knob (or bass enahncement) in the real world. The Fletcher-Munson curves are real. The bass is not very "loud" at low levels, why should it be so on our stereo in the living room?
Paul is absolutely correct given the above assumption about the goal of accuracy. I agree with him. I will confess; however, that on occassion when I can not turn up the level I will resort to a "loudness" knob.
Good Luck,
-Tom
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Dr Who,
1) Yes you still need a mono amp for the center channel
2) I built both versions. You are correct about dropping the level down to line level and having to amplify again. However, in the top version you lose a bunch of gain on the L & R channels. In my case, I was using a passive preamp and did not want that.
3) No way around it, you still need another amp (or channel) for the center
Good luck,
-Tom
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They regularily come up for sale on eBay and Audiogon. A typical price would be $600-800. This depends on condition and finsh primarily. The Shipping costs/headaches should also be considered.
In the early 80s the CW went through some changes and became the CW2. Both before and after this; however, there were some incremental changes within the each series. These included included slightly different dreiver/horns, crossover mods, and orientation of the horns. Although these changes would alter the sound, they will all have a fairly similar sound (more similar than dissimilar).
I did want to mention that if you are patient, you can get a deal on these. In my case, my good fortune was due to some very kind and conscientious members of the Forum who scour all the local papers and classifieds and share the info with the rest of us. In my case I was able to get a pair of mid-1980s Cornwall 2s (oiled oak in very good condition) for only $400 (located in about a one hour drive). I have benefited from the kindness of these good Forum members.
Good luck,
-Tom
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Let me ask the very, very obvious question (before folks get into suggestions about esoteric audio cable ....)
You mentioned that the cabinets were demo models at the stereo store. What did they sound like at the store (assuming they were reasonably set up in a corner)?
Was the bass lacking and the highs overly bright? If not, then the path heads toward setup, location and room treatment (although were they being run with very different electronics at the store?). If the sound was similar, then this is now an issue of trying to muck with electronics and room treatment to change the sound.
I have older K-Horns (and also Conrnwalls). In my opinion (and this is certainly painting with a broad brush), the K-Horns sould sound more similar to the Cornwalls you are already familiar with. The highs should be approximately similar and the bass (with some caveats) should also be similar
Good luck,
-Tom
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I am also interested in trying a mod or an upgrade for a CW 2 crossover.
The topic has drifted a bit, however.
The ALK mod for a Cornwall is NOT meant for a Cornwall 2. Getting back to the original question: Has anyone thought through (perhaps even simulated / built / measured) a crossover for a Cornwall 2.
I appreciate that there is a great deal of work in crossover design and I also appreciate that not all Cornwall 2's use identical drivers/horns. So the question becomes especially tricky.
I am interested in your collective wisdom.
Good luck,
-Tom
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I am going to definitely agree with the folks who are mentioning: speaker placement and room treatments.
The room treatments (as first step) can be fairly simple, such as adding (or removing) an area rug, carpet pad, drapes, wall hangings, or removing a couple of pieces of furniture. The effects are real!
-Tom
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Yes, Malcolm is absolutely correct. Outdoors is best.
Folks usually do this because there is a lack of sensitivity or other signals creep in (a couple of reasons for that). An indoor/amplied antenna usually is pretty ineffective.
I don't know the specifics of your situation, so take my advice with a grain of salt. What I did (I live in a semi-rural area in Southern New England) was to mount a Yagi antenna on the roof. You can get a dedicated FM one at Radio Shack. They have 2 versions. When they are on sale they are $15 & $19. Get the more expensive one. These are quite directional so you probably also need a rotator (about $35). This will give you better gain and also reject unwanted signals (same freq but but from another direction). The option of puttin it in the attic is tricky, Even though there may not be much metal in the attic (of a typical house), they do seem to work very well in practice.
Good Luck.
-Tom
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Good Question.
The Watco products are great for the oil finishes (great for re-finishing also). The process is a bit involved to do it on frequent basis, but be sure to follow the instructions.
Regardless of what you end up using, please do NOT use any product that contains silicone (these are usually in the products that you would use on a weekly/monthly basis).
Good Luck,
-Tom
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Yes, it is a good starting point.
They have a similar tweeter and a roughly similar mid-range. The cabinets are a mangable size and cost.
Similar to their big brothers, they are amazingly efficient. You will not need a big amp or one that delivers a lot of current. However, the amp (and other compents) must deliver a clean signal. Any hiss or hum will become quite audible.
It's a nice journey - welcome!
-Tom
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I appreciate al the the interesting comments I have been getting so far.
Yes, I have been ignoring the fact that the distortion in a ss amp is not always when it is being driven at max levels. I also forgot to mention that this is strictly for music (no HT) so no sub-woofer is required - I would not want to muck up the low-freq response of the K-Horns
A number of folks have been recommending tube amps. That is natural in this sort of context. However, in my mind, I am not sold on the "tube sound" . The overall differences between a decent SS and decent tube amp are complex and varied. However, for me, I do not prefer the tube sound. This is not baiting and it is not meant to be controversial. It is simply my preference.
One thing I forgot to mention is that I have not yet refreshed the crossovers on my K-Horns (or the Cornwall center) yet. I am not convinced that the latest flavor in capacitor construction will create some acoustic magic. However, some good folks on the forum have made a reasonable argument that refreshing the caps in order to eliminate resistance that has built up over the last 24 years would be beneficial. The notion of putting a resistor in series with the drivers is pretty convincing. Perhaps I should do that first. I have held back partly out of laziness (hey, I am remodeling my kitchen right now - with no end in sight). But I have also held back because of the interesting threads regarding crossover design. Design is a complex issue with many variables and compromises. I am very tempted by a steep slope filter (for the woofer/mid) that Al K has made available. He makes some very interesting and thoughtful arguments (my cabinets currently have original AA networks) and the center is a Cornwall II (circa 1987?) .
Previously I had auditioned K-Horns driven by Luxmans and by Haflers and was blown away by the sound. That was motivated me to get some K-Horns myself back in 1996. I still love them although I do dabble with panel speakers in my other set ups.
I do appreciate everyone's perspective. I assume that I am merely going through what the rest of you went through before. I want to capitalize on your collective experience.
Thanks,
-Tom
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Thanks for the opinions so far.
Unfortunately it is a bit difficult to describe the audio expereince with the different amps. I originally got the Hafler to drive some Magnepans (they are a tough load - inefficient and and low impedance). The Hafler did pretty well, and it seems to do okay with the K-Horns .... but not great. I have it driving the Cornwall center channel where it seems to be a better match.
The Carver TFM I have found to be clean in its output (pre-amps have been a larger source of noise, hiss, & hum). But again the sound is nothing special. Actually at the low frequencies the Hafler seemed to do a better job. At the higher frequencies, the Hafler is probably preferred. To my ears, the Carver was a bit harsher than the Hafler. The mids semed to be more accurate with the Carver.
In either case there was sufficient power / headroom so the there was no distortion or clipping.
Thanks again and I know you guys have solved this problem before (specifically: matching solid state amps that I could not afford 20-30 years ago with K-Horns).
All opinions welcome,
-Tom
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I confess I have a bit of the upgrade fever right now. I am currenrtly using a Hafler amp with my K-Horns. There are so many neat solid state amps from my youth that are now reasonably priced that I am interested in sampling some of them (NAD, Rotel, Luxman, Adcom, Onkyo, HK, Phase Linear, Marantz, etc) .
To start with, are any folks also using Carver TFM models, or the Phase Linear versions, or Hafler amps with K-Horns. What are your impressions? I am not interested in enormous amounts of power but rather in a wonderful sound.
Some of the equipment I have tried has suffered because they were not sufficietly clean. The K-Horn's efficiency make the noise, hiss and hum come through (this was the case for or the Dynaco, or at least the ones that I tried).
Your opinions are appreciated. I listen to Classical & Jazz (CDs not vinyl) at reasonable levels in a 12x19 room
Thanks in advance (I know it is a difficult question since we always focus on our "own" systems),
-Tom
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Michael,
Thanks for the post. However, I am still confused about where the DC might be coming from.
Let me digress. When I was new to DSP, I frequently would make a waveform (in floating point arithmetic) that would exceed the number of bits (when converting to integer arithematic) during the DAC conversion. It's a rookie error, and everyone in the lab was guilty at one time or another.
We would always catch the error when we hooked up the spectrum analyzer. If we were generating a sine wave for instance and went beyond the 16 bits, the signal was definitely clipped. The tops and bottoms (an AC waveform) were both flattened out. This I believe is the same thing that happens with an amp that cannot drive the transducer "far enough" (perhaps a lack of sufficient / transient levels of current - if the driver has a low impedance). I assume the effect is comparable if the driver excursion is impeded in a mechanical fashion.
The reason I mentioned the specrum analyzer is that the effects of a clipped waveform were easily seen. There was harmonic distortion at the odd harmonics. With a Fourier analysis this would also be expected.
My question: if the clipping is for both the "tops" and the "bottoms" of the waveform (and clipping from the mechanical limitations may not be the same) and the clipping in both directions is the same magnitude, then where is the DC coming from? Additionally, the harmonics introduced were usually 10's of dB down so I can't imagine that any extra energy going to the tweeter would be appreciable. Certainly the signal sounded like crap, but I don't see where the damage would be coming from.
Is it the case that the clipping is asymmetric (more flattening in one of the directions). Then certainly a DC component would be added.
Curious,
-Tom -
Yes, it is a good obeservation/question!
At very low frequencies much of the level you receive at the ear is very much a function of room geometry/acoustics.
With very long wavelengths, drapes, furniture and carpets do very little to break up the low frequncy waves. Consequently, what you heard (the increased level) was due to standing waves. Bass traps (usually placed in the corner) are one of the few ways that you can even out the sound. So that is a possibility.
The other major approach is to experiment and move the position of the speakers (mostly relative to the floor, if they are on risers, and relative to the rear and side walls). This will certainly impact the imaging & sweet spot however. Additionally, when you re-locate the speakers it will not typically reduce the uneveness of the low- frequency repsonse. Rather, it will shift the loud & weak spots to a different frequency region (you will still have standing waves).
Good luck,
-Tom
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Re: "Q" or quality factor
I am confident that both Al and Shawn know the definition, but I did not want others to get confused.
The "Q" is a relative measure of the bandwidth of a filter (or other devices) . The measure refers to the ratio of the center frequency divided by the bandwidth. Where bandwidth is defined by the half power points (3dB down points) . So if the device lets frequencies 10% (above and below) around either 100 Hz or a 1000 Hz (or bands of 20 Hz and 200 Hz) then the Q in both cases is the same: 5. So it is a measure of bandwidth relative to the center frequency. The bigger the number, the sharper the tuning.
Good luck,
-Tom
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It really would be a crap shoot.
Without having the T/S parameters, you are setting yourself up for a series of headaches. The cabinet geometry, porting, crossover, insulation are all designed and tweaked for the specific driver.
The K-33 is a good driver already. Is there some aspect or deficiency that you are concerned about?
Good Luck,
-Tom
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Gee, I could not disagree more with The Ear's (tactless) comment.
My thought is that I would like sire children with Amy. The offspring would be beautiful
-Tom
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I have a couple of the other NAD tuners in the 4XXX series.
They are quite affordable and pretty good quality. So I believe they are a good value.
I will say the biggest improvement came when I placed a $19 Yagi FM-antenna (Radio Shack) on a rotator up on the roof. I listen to a bunch of NPR & college stations in Southern New England.
Good Luck,
-Tom
Which SS power amp to mate with Peach & Khorns?
in 2-Channel Home Audio
Posted
Coytee,
I also have K-Horns, so I will interested in the repsonses that you get.
However, let me ask an innocent question: Why in the heck would you need 200 watts of power with a speaker that is so efficient?
Seriously, is it likely that an amp will be both clean sounding, dead quiet and also have that much wattage. My limited sampling has indicated that the efficiency of the K-Horns is ruthless in revealing any hiss, hum or distortion in an amp (or pre-amp or source).
Good luck,
-Tom