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HIThat cap calculator is nonsense. They want you to assume that the LF rolloff will start at 10X the value of the -3 dB point. They want to sell you a large and expensive cap. The reality of it is that 3 octaves is plenty and 2 octaves is really sufficient. An octave is 2X the frequency value. So even 3 octaves is only 8X. If you keep the - 3 dB point below 5 Hz I seriously doubt you will hear any LF loss into your amp. If you really want to drive a 10K load then you can go 3 uF. Into 10K to get a 5 Hz -3dB point you need 3.185 uF of capacitance. So 3 uF is fine. The thing is, that besides cost, there is a tradeoff in sonic quality between values as you get a larger cap value. More phase error, etc... I cannot hear any difference in cap sizes up to about 3 uF. If I put a 4.7 uF cap in I don't think it sounds quite as good. So you are using a larger cap to avoid any rolloff at all below 20 Hz and giving up sound quality. The reality is that there is little if any music below 25-30 Hz unless you are into electronica or Bach organ fugues. Piano goes down to 27.5 Hz and bass about 30 Hz. Also, most people don't have speakers that will play below 30-35Hz. So if you use a 3 uF cap you might get a smidge of LF rolloff into 10K between 20 and 35 Hz, but your speakers and the music itself don't go down there anyway. So you put a 4.7 uF cap in the preamp to get performance you don't need and it doesn't sound quite as good as the 2 or 3 uF cap. Quite frankly I never understood why on Earth a manufacturer would make ANY amp with a 10K input impedance. There are plenty of good SS amps out there with 47K input impedance and some are 100K. It has nothing to do with SS vs. tube. Any tube amp I have ever seen is 80K or higher and most are 100K. My KT88 amp is 220K. If I am building an amp and matching preamp for a customer I use .33 uF caps. That gives a -3 dB point of 2.2 Hz and a nice small output cap.
What would be the optimum cap value for my monoblocks. They state "INPUT IMPEDANCE : 130kOhms in parallel with 82pF". I have very large full range speakers can play down to 20hz. Thx.
Those isolation devices are not exactly or even remotely attractive or inconspicuous!I'll stick with the Herbie's Tenderfoot!
I am from Brazil and received my Don Sachs II with Shuguang treasure 181-Z and 2 different exits, one of them with 3.0 cap recommended to my Accuphase P-6100 (20 Kohms out). What I can say is that I am simply loving it. Spectacular timbre, with great bass and mid / treble sweets, which are making me listen to music for hours without fatigue. Despite the difficulty I had in importing him to such a distant place. Very happy.
I just finished my VTA SP14.
Michael,If I was new to building I would buy the kit from Roy. The board is designed and all the markings on the tube side and the chassis that comes with it is designed for it to site inside the chassis. It makes it easier for a new builder. If you practice soldering it should not be a problem. You just need to make sure you heat both the part and PCB your solding it to. You start with soldering the lowest parts first and work your way up. The instructions are not bad you should read through them a couple of times, and there is a lot of additional information on the website.The Landfall chassis are very solid 1/8" aluminum. I have used them in a couple of projects and Dave is great to work with.Brad
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