CWelsh
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Posts posted by CWelsh
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I think I may have found part of an answer in a Stereophile review from 2019.
"I found that the speaker's impedance magnitude (fig.1, solid trace) dropped below 6 ohms only in the upper bass and in the valley between the twin low-frequency peaks that define the reflex woofer loading. The minimum value is 3.65 ohms at 125Hz. However, the electrical phase angle (dotted trace) is sometimes extreme, and there is a current-hungry combination of 5 ohms and –49° phase angle at 90Hz. Despite its high sensitivity, the Forte III will work best with amplifiers that are comfortable driving 4-ohm loads. And the very large difference between the average impedance in the lower midrange and that in the treble means that the speaker might sound a touch bright with tube amplifiers having high output impedances."
I was pretty sure I had read somewhere that the impedance dropped down below 4 ohms at some points. This may explain why the bass sounded tighter with the Fisher vs. the ACA.
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26 minutes ago, DirtyErnie said:
Doing a little reading about the amplifier mentioned, sounds like a high-voltage, lower-current implementation on that amplifier. But physics is physics; unless he has a good current-limiting circuit on the screen grids, plugging a 4-ohm speaker into a sub-4-ohm tap will force the load-line lower, will increase your Class-A power, and will push the load-line out the left side of the chart, and that will cause lots of current to want to flow out the screen grids if you push the tubes to the limits.
You can't cheat physics, but you can mold it to your advantage if you're willing to accept the consequences (and maybe design around them).I don't understand most of what you're saying, but I'm glad people are engaged with the question.
I have the Fisher amp listed for sale on Reverb thinking I could use the funds for other enhancements to my system. However, I'm starting to rethink. We have a shop in town that refurbishes vintage audio equipment and I may take it in for an evaluation. @83 LSIs question of whether it is operating at 100% has me thinking.
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6 hours ago, hellis739 said:
Being equally or even more ignorant, I just wanted to contribute to your discussion with my experience. It might be more beneficial for someone instead of getting involved in an endless technical dispute, to go the other way round and do a test powering the speakers with a powerful (at least 100W/ch) amp. Of course ,if you are certain that your Forte perform according to their full potential powered by a 2* 8W amp with any type of music then you do not need to do any test at all. But I think that we should not confuse the gain and the SPL with the power of an amplifier. The transformation of my speakers is much more "obvious" when listening to music at low volumes.
A key part of my question that I may not have articulated well is, regardless of the amps rated power, how much of that power is used to drive the speakers to an equal SPL?
There was a thread sometime back where a simple method of measurement was described that identifies just how many watts are actually being used to drive the speakers to the desired level. If an equal two amps with significantly different power ratings can drive the amp to the same level, it makes sense to me that the same wattage is being used to do so. And, if that is the case and you are noticing obvious benefits from the higher power amp, I have to wonder if the benefits are from something other than the actual power at the speaker terminals.
Please understand, I am not questioning or disputing your experience...others in these forums have said similar things. I'm just wondering if there are factors other than just the power capabilities of the amp that make the difference, or if that extra wattage contributes to more than just the power used by the speakers.
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2 hours ago, hellis739 said:
Good morning to everyone. Since the beginning of the year, my Klipsch Forte III are powered by a class D Hypex 2*250W (8ohm) and I can honestly admit that the speakers never performed better in the past. Compared to the class AB 2*50 (high quality) amp I used for the past 15 years, now there is a completely different (neutral) tonality ,much more detail in high frequencies and absolutely controlled lows. Make no mistake. The Forte ,the Cornwall and the Heresy speakers may be efficient according to the specs but their (12'' or 15'') woofer is conventional and not a horn. This means that they need power (the peak power according to specs is 400 W and not 100) and class D provides VFM power. You can have the same result using a powerful AB or A class quality amp (such as Accuphase, McIntosh etc) but not for the same cost.
So, I ask a sincere question...not to stir controversy, but out of ignorance on my part. My question starts with the fact that my 8 wpc amplifier will drive my Forte IIIs to what I consider an almost painful SPL. And, I make the assumption that a speaker that is not biamped will have the same amount of power going to the conventional woofer, and the mid and high frequency horns. Am I wrong in my thinking? I can maybe see that higher wattage can provide better control (damping?) of the woofer, but I'm not sure I understand how, exactly. Does the amplifier class (A vs. AB vs. D) have something to do with it?
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You might check with Hawkeye Audio in Iowa City, IA. As far as I know, they are the only Klipsch Heritage dealer in Iowa.
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The link isn't working for me now, either. It worked when I put it up. I'm checking with the seller, but it looks like he either sold them or took down the ad.
Just messaged him. He had set them up so he could demo them if someone was interested, but after listening for a while he decided he wanted to keep them...LOL
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I know there has been some stuff posted about using active crossovers, but I'm specifically curious about the Pass designed biamp crossover from DIY Audio. Anyone have experience with it, particularly with Forte IIIs?
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Welcome to the club! I am also a Forte III owner (also my first ever Klipsch), and share your enthusiasm.
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This is in a Facebook thread I follow.
https://www.facebook.com/commerce/listing/1105454427160063/?media_id=0&ref=share_attachment
I have no affiliation or interest in this offer.
Owner isn't sure, but thinks they are from the mid-80s to early 90s.
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5 hours ago, seti said:
Don't chicken out just replace the big can caps with some from Heyseed Electronics and that big brown electrolytic and you will be most of the way there. I love these fishers and can't get enough of them. Good luck.
It is the big can caps that really scare me. They are buried under a rat's nest of wires and have multiple wires connected to them. I recapped my Marantz 1060 and even replaced a few transistors, but everything is mounted on boards and is clean and easy. If it wasn't such a nice amp, I would try it. I just don't want to mess it up when I know someone with experience could restore it to better than new condition. I've even got all the new caps and am including them in the sale price.
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17 hours ago, 83 LSIs said:
I wonder if the Fisher is working 100% since it should play at least as loud as the ACA.
How old are the tubes?
I suspect it may not be working 100%, but I don't have the ability to test it. I've had this amp for more than 25 years and haven't done anything to it. I'm pretty sure it was in storage for at least 5-10 years before that. All of the tubes except the rectifier are Fisher brand, so it is possible they are original. If not, I will bet they are at least 50 years old. Both channels are working and, to my ears at least, sound even. In fact, the sound stage sounds really nice.
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On 3/10/2024 at 6:39 AM, tube fanatic said:
I speak with Henry almost daily and he is quite well but is pursuing other interests at the moment .
Maynard
Thanks, Maynard. I'm glad to hear it.
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The experiment was successful! I tried the Fisher using the 4 ohm taps and it made an amazing difference. The output volume is significantly increased. Surprisingly, still not equal to the ACA. However, the Fisher gives more oomph to the bass. Other than the bass, though, I prefer the ACA.
It's fun to learn new things!
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This amp is fully functional and in outstanding original condition. I had it hooked up to my Fortes and my music streamer recently and it sounds wonderful! Since the amp is over 60 years old, I was going to replace some of the critical capacitors, but after taking a look underneath, I chickened out. I'm including the new caps, a parts list, and the schematic with the cap locations marked.
I don't have the ability to fully test the amp so I am selling it as is. In preparation for recapping, I opened everything up and did a deep clean. I used Deox-it on all of the terminals, connections, pots and switches. Everything work smoothly and noiselessly, and seems to be doing what it is supposed to.
As far as I can tell, everything is original with the exception of the rectifier tube and the brass caps on the knobs. It has the original oiled walnut cabinet and the brass mesh vent panel is even in great shape!
The amp is currently listed on Reverb for $995 and I may try a couple of other places.
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My first experience with Klipsch was a long, long time before I owned a pair. I was in a store called Audio Labs in Des Moines, Iowa, probably about 1972. I spent enough time there that I had gotten to know a couple of the sales people fairly well. When I walked in one day, one of the guys grabbed me immediately and dragged me into the large room where they had a pair of K-horns powered with bi-amped Audio Research 100 wpc tube amps. He sat me in the sweet spot and fired up Karn Evil 9 by ELO. It was mind blowing! It took me 50 years to buy my own...not K-horns, but I'm happy.
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This is my Fisher X-101-B. I finally took it apart to do a deep clean including using Deox-It on all the connectors, switches, pots, etc. I was planning to replace a bunch of caps, but chickened out when I opened up the bottom panel. YIKES! Instead taking the chance of turning the thing into a boat anchor, I've decided to sell it. Besides, it works great as is, so I can enjoy it until it sells.
I recently read an article from Audio Research suggesting that just because a speaker has a nominal 8 ohm rating, tube amps may work better using the 4 or even 16 ohm taps. I tested this one using the 4 ohm tap and it made an amazing difference. The amp sounds great, but I still think I prefer the ACA.
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@The Dude If you don't mind me asking, what are you planning for your new preamp with phono section project? That sounds a lot like what I want.
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The specs for the Forte III say the impedance is "8 Ohms compatible" and I'm curious what that means. I just saw something from Audio Research saying it pays to experiment a little with which impedance tap you choose when using tube amps because a "nominal impedance rating" of 4, 8, or 16 Ohms may be misleading. Apparently not the case with SS.
I have an old Fisher integrated that I have tried with my Fortes and I wasn't overly impressed. The Fisher is rated at 28 wpc, and my 7 wpc Class A ACA just blows it away in terms of output volume. I haven't done any experimentation using different output taps on the Fisher yet, but expect I will. I just wondered if anyone else has any experience/thoughts?
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And, this is supposed to be a hobby we enjoy and share.
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At AXPONA last spring, I attended a session on streaming and was surprised by how many "industry experts" suggested using a laptop with a DAC dongle as a great way to get started in streaming. They did all say you would probably want to move up to a dedicated component for extended functionality, but they didn't seem to suggest the audio quality would be significantly superior at the entry level.
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9 minutes ago, The Dude said:
I had a good experience with a tube line stage from Tubes4hifi.com. I ended up selling that line stage to fund a new project, but do have a similar line stage that I will be building into a pre amp with phono section. All of this comes from Tubes4hifi.com. Note, this is running a tube pre/line stage into a solid state, some frown upon it and prefer to run SS pre into tube amps, YMMV. If I was going to go SS, I would look at Diyaudio again for something from Mr. Pass.
I've looked at Tubes4hifi.com. Very interesting stuff and the prices seem reasonable. I have to admit, I find the website a bit difficult to decipher. I've also looked at Elekits. What tips me to Tubes4hifi is the remote control option.
As for tubes into SS vs. SS into tubes, I have no bias either way. I would love to be able to try a nice little SET amp sometime, but I have an old Fisher integrated that I've hooked up to my Fortes, and it does sound good, but I definitely prefer the ACA. Maybe it is just that it is Class A. I don't know.
I've looked at various options from Diyaudio and will likely go that way if I stick with SS. I snagged one of the active crossover/bi-amp kits and want to see what that does. I have the technical skills to handle the assembly of kits, but I'm not sure I have the knowledge necessary to combine various pieces into a whole. I think I need a mentor...LOL
My goal is to have a great sounding system, but I have no illusions that it is going to be the creme de la creme... that is beyond my means and even beyond my ability to appreciate. However, being able to say I built it adds significantly to my appreciation.
Sorry for rambling so much. I really appreciate your feedback.
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Denon PMA 600ne with Klipsch RP 500m speakers
in 2-Channel Home Audio
Posted
Rather than switching amps, you might consider replacing your speakers with something with higher sensitivity. I think you would get more bang for your buck. Your RP 500m speakers are rated at 93 dB sensitivity. If your budget can handle it, the RP 8000F II is rated at 98 dB. That is a big difference.