Curious_George

Not to stereo type, but over 20 years of dealing with Chinese vendors, they are (almost) all the same. They have a unique way of looking at the world and their government. Even the ones who came here very young and can call themselves US citizens seem to have a strange calling to support China in some way. I'll leave it there for now, but do some research and reach your own conclusions.

I recently had the idea to design a universal SET pcb similar to the *Get*SET*Go* pcb that was popular many years ago on a different forum. It is based on a 6EM7/6EA7. I built the circuit and it performs quite well. It will drive 70VRMS (200VP-P) within the audible band (20Hz~20kHz) easily with decent distortion figures. Some minor tweaking at the higher drive levels should help reduce distortion some.

Hey Racer, have not heard much from you lately.

I believe the reason Klipsch used these types of filters in the old(er) series was because at the time, they were the most common type filters for the day and age. https://en.wikipedia.org/wiki/Constant_k_filter Although the use of a constant k filter has been criticized by ALK, they do work fairly well and many people have enjoyed them in a lot of Klipsch speakers. The worst offender for bad sound seems to be the K-400 horn.

I love (loath) a technical thread with no pictures, graphs or charts to show you what is going on...

Most people who are seen as eccentric or self-proclaimed eccentric are usually self-aware to some level. They know how they are acting and usually don't care how they are viewed. Although I have never met him, people like Nelson Pass are rare. A great designer and person in general with a lot of patience and always willing to help if he can with DIY, but also has a business to run. So many has or have beens get into the audio world and then disappear after a short time. The list is long, but usually not too distinguished.

Well, my question can be sent via PM, which you seem to like a lot...

Could you expand on this "moral center", I am curious.

One thing to keep in perpective (especially for non-engineer types) is that measurements are "tools". It seems a lot of people dismiss measurements and say their ears are the ultimate test & measurement system. Our ears can easily mislead us and test measurements help guide us to make informed decisions. It has been well established that measuremetns alone should not be used to formulate opinions about what equipment to buy; you should listen to music you are familiar with as well on the equipment. In addition, most people don't know how to interpret the test measurements which only adds to the confusion when trying to make an educated buying decision. Not in this case, but in a lot of other cases as captainbeefheart has pointed out, there is a huge amount of info on YouTube, but you need to wade through it and separate the good from the bad info.

I agree with you, it's the person I quoted you'll need to convince...

There is truth in what Schu has quoted above, but it is all relative. There is a long history of equipment that does not have the best bench test results, but the sound quality is very listenable and in some cases, there is a cult status of said equipment. In other cases, the equipment bench tests are great, but the amp is cold, sterile, analytical, etc and in general, people do not prefer the sound.

You mean the "ported bass horn half-baked" solution? (A quote from another forum member, which I disagree with)

Here is a link with a little background on the VTA ST-70; https://www.audiophilenirvana.com/audiophile-equipment-reviews/dynaco-st-70-timeless-classic/

Are you in the market for a new amp Henry?

Exactly. Sounds like a suitable time for a Forrest Gump idiom, but I will refrain since I promised the moderators I would be on my best behavior.

Here is some reading that will surely turn your brain into mashed potatoes in short order. If anything, you can learn a lot more adjectives for describing what you hear. https://www.diyaudio.com/community/threads/resistor-sound-quality-shootout.377009/

The two carbon film series are similar. The SPR type come in wattages from 0.25W to 5W. They are classified as power series resistors due to their features. The tube amps guys use them, especially the 1W to 3W values. The CF should work fine for your application. Apparently, a lot of Japanese DIYers like the KOA SPR series. I’ve seen a few images of Japanese builds using SPR’s.

A question about a questions usually infers clarification. This is how humans communicate effectively.

These carbon films are popular and well made. Supposedly they are as quiet as metal films which kind of makes you wonder if there is an audible noise difference. I have used standard ole carbon films in solid state amp rebuilds and can get 95dB signal to noise unweighted noise figures. Typically, the active components have more noise than the resistors unless you use a carbon comp in the wrong place. SPR-12666.pdf

Unless you do the math for the resistor ratio, you need to use the online calculator(s). When you start adjusting your two discrete adjustable wire wound resistors, if you don’t keep the ratio correct, the impedance seen by the crossover network will change, thus changing your crossover frequency, then you will be changing the level and the crossover frequency.

So in other words, you want to use two discrete wire wound adjustable resistors and dial them in to attenuate the HF driver?

You can use an L Pad, dial it in, then measure the values and use two discrete resistors.

Ha… that’s what they all say…

You will not hear a difference taking the Zeners out unless you drive your speakers at higher levels where the Zeners would normally start to shunt the drive signal.

The Chinese (some) are like Trelain from Star Trek In "The Squire of Gothos". Trelain was looking at Earth, but the Earth of the past. He didn't realize that what he was "seeing" was not the present Earth. Anyway, Trelain recreated everything period correct, but the food had no taste and the wine no flavor. The Chinese usually do the same thing, it looks good until you look behind the curtain. I was in a meeting once, with some Chinese fellows, we got on the subject of the Chinese stealing US military secrets and the Chinese guys said the "Chinese" were smart because if you could steal what you didn't have and learn from it and save time and money, that that was smart.