Curious_George

I have some limited experience with ICE Power modules and Sunfire amps. The ICE Power was back in 2004 or 2005 when they were trying to get a foothold in the US with a name brand. Deal never went through, but the amps / modules passed all of our testing. There was no protection circuitry whatsoever, so we had to design short circuit, over current and DC Offset to withstand the mobile environment. The Sunfire amp, as you probably already know is not really a class D amp, but a switching power supply that tracks the music signal and delivers just enough voltage and current to the analog amp to operate (the amp) in an efficient manner. Ingenious concept if you ask me. Have not built any class D kits. I'm a die hard analog fan.

I'll tell you WTF... your "gentlemen" Mr. Claude elevated the level of the conversation by his presumption and tone, but I am certain he is well aware of it. It seeps out quit often. I expressed an opinion about his fondness for class D amps (which I must admit, knew would lead to some anecdotal story about multi-thousand dollar equipment he had experienced) only after his very broad dismissal of Phase Linear amps for Khorns. Do I care? No. Everyone has their favorite amps. I just thought I'd let Claude know what I thought at that moment. No hard feelings either way. As I have said for many years, being on these forums is like being back in high school a lot of times... entertaining to say the least. Fortunately, there is a good amount of constructive info as well. Gotta run, I just heard the bell.

We’re not even, but I know from perusing this forum that you come across as brash sometimes and that’s ok. All the forums are alike in that regard. I’m not a proctologist, but I know an a$$hole when I see one. One of my favourite sayings…

I lived in Florida for 48 years (Jacksonville and Orlando), maybe I was lucky, but power was usually fairly reliable. A lot of people in Florida have heat pumps since it doesn’t get too cold, although my last home there I bought had an HVAC with electric heat assist only.

One of the classic sci-if movies no doubt. “Standby to reverse polarity”…

BOM. The bean counters use to drive me crazy trying to save $.25, which equates to $1 at retail.

That is a subjective answer. I would say that a class D amp would be one of the worst for any speaker, except a sub, but that is my opinion. I partially agree with your answer though. I prefer the Series I over the Series II. The Series I, if rebuilt and modified for full complementary output stage, can sound extremely good and are quiet. The Series II were noisy and a bit more reliable than the earlier Series I, but that was mainly due to the better output transistors used in the late 70’s compared to the early 70’s. If you have never heard a PL 400 or 700 modified and brought up to modern “standards” you would be amazed at how good it can sound, even on Klipsch speakers.

Just wondering what members have built for use with their Klipsch speakers. I’ve restored (and modified) quit a few Phase Linear amps, and for some reason, have a soft spot for them. Currently, I have about 14 various models. Depending on the model and series, I prefer some over others. I have a late model 700B with 3 prong power cord and dual primary power transformer. It has been kept stock for nostalgic purposes. I also have another 700B chassis that I am using as a “test mule” to design new amp circuits. The amp topology in it now has 10 T03 outputs per channel (just like a normal 700), but the pre-driver and driver stage are operated class A, not class B. The output section is full complementary. The input driver board is a balanced input design with a slew rate of about 40V/uS. Similar to a 700B for output power: 350 watts per channel into 8 Ohms, mono 1.1 kilowatt 8 Ohms. Krell KSA50 clones - These amps sound pretty good. Very dynamic and revealing. AB International 600LX amps - one stock, one modified. Decent amp for the money. Easy to modify, triple output design.

I recently purchased the Duromax EP12000EH for my home. Installed the outside 50A receptacle, transfer switch and new sub-panel. I've got about 13 hours on it and the system has performed great. I'm selling the 12k and upgrading to the 13k, so I can run both of my HVAC's, if needed. I have a 500 gallon in ground propane tank to tap off of. Overall, the Duromax have good reviews, but it looks like you could still get a dud if the shipper is not careful.

No, not for $450. I am very familiar with working with American and Asian vendors. 10 years to improve the 55 that much deserves a medal for patience and commitment.

Nice… a perfect mid-summer project.

10 years to develop? We went to the moon and back in less time… the frequency response does not look that improved.

The type A is only a 6dB/octave slope on the tweeter and will allow more low frequency energy thru to the tweeter. This may be perceived as more "warm" or a slight bloom in the frequency area of 4 ~ 6kHz. The type AA is an 18dB/octave slope and much steeper although it is an older 18dB type alignment (still effective). The 18dB/octave slope will have less driver interaction and possibly a more "clinical" sound. I hate using audiophool adjectives, but people seem to understand when you use them.

Ease of production (i.e. - it is fast and easy to do).

Yep... triodes don't amplify RF very well.

I don't have a direct coupled 300B design handy, but one based off of a Loftin-White 2A3 design comes to mind. Should be fairly easy to design & build. Monkey on a stick??

I don't have any suggestions for a speaker repair facility. Most shops will probably want to remove the dust cap so they can ensure the voice coil is centered. However, unless a near identical dust cap is used, the mid-range performance of the woofer will be slightly different. This may or may not be audible, but your woofers will be back in operation.

i would recommend Don Lancaster’s Active Filter Cookbook. It is heavy on math and theory but an excellent read. It is an analog based book, not DSP.

Is the entire spider loose or just a partial area of the spider? You could re-glue the spider back down with slow setting epoxy and the surround should keep the cone centered if you are careful. I have re-coned speakers before and epoxy is normally used on the spider to top plate / basket interface.

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I should have expanded on my thought... as far as "newer" versions that people or companies design & build of the WE91 with modern source equipment that have much higher output than sources in the early part of the 20th century. Having all that gain (when not needed) with a pentode will just increase noise. BTW - pentodes have more sound of their own than triodes, not vice versa, but I guess that is subjective.

I realize the WE91 amp and its derivatives are historic. No question about that, but for HiFi, I don't understand driving one of the most linear tubes made (300B) with a pentode. I have never heard a WE91 and I'm sure it sounds wonderful, but a triode driving a triode would (or should) sound better. I imagine the pentode front-end will impart some audiophile adjectives to the final sound. Just saying...

Do I see some big transmitting tubes that are interstage coupled?

Congratulations!

"The Variovent consists of two grilles with some damping material stuck in between. Simple as that. The diameter, amount of damping material and the compression of the material determines the air flow properties = acoustic resistance. The late Gilbert Briggs (Wharfedale) made slits in the rear panel and added damping material over the slits. Works the same and costs nothing. But you have to be able to follow the impedance of the system to tune the amount of damping material needed. The Variovent is a device sometimes causing much debate. What is an acoustic vent? Well, an acoustic vent allows some ventilation at low frequences and virtually none at higher frequences. So what's that supposed to be good for? Neville Thiele studied the Variovent in detail and concluded it didn't offer any advantage over a properly designed vented systems. The general advice on the use of acoustic vents is simple: Try it! Which offers little comfort to those addicted to math. But box calculation based on Thiele/Small data really only apply for speakers with a Qt = 0.35, which only counts for very few drivers. Based on experience we use speakers with high Qt in cabs too small and drivers with low Qt in cabs too large compared to strict box simulation. Comparing the impedance peaks of a driver in free air and a perfectly closed and empty box should reveal the same peak height, so we have no loss in the closed box. Obviously the resonance frequency is higher. Adding damping material to the closed box we see a decline in peak height; now we have some loss. Adding an acoustic vent may produce a significant reduction in peak height depending on how open the vent is. So, the system Q-value is lowered (= more loss) from applying an acoustic vent although we really can't speak of a Q-value of an aperiodic system. Basically a closed box has 2nd order roll-off, a vented system a 4th order roll-off and the aperiodic system a 3rd order roll-off." I messed around with this years ago. Does a Variovent work? Yes. Did it audibly change the sound? No, not in my case, perhaps because my enclosure was close to the correct size. The leaky vent concept is mainly for sealed enclosures that are smaller than optimum.