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MyRef_C with Ultimate BOM

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#243
I have spent some time (gratefully financed by my boss) to made a pair of simulations with 1uF and 2.2uF. At 20Hz, attenuation is null on both, far less than 0.1dB. What goes a bit down is phase distortion. Have a look at them.

I need to make ones later more focused in 20Hz and above, to see better the differences.
 

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#244
I can't say with any certainty what effect the two sizes will have. My input cap is 0.68, and I think that is too small for a full range amp. The lowest bass gets a little sloppy, although it's still there and sounds okay. The only advantage of a smaller value cap, if not cost, is size. Both offer a low enough cut-off, but the larger cap will provide lower phase distortion. If your speakers (and music) really go down to 20hz, the larger cap is needed. I always intended my amp to be used only for mid and high frequencies, with a more powerful amp for bass, so a smaller cap means nothing significant is distorted. When run full range, they suffer somewhat on organ and lowest bass notes.

Peace,
Tom E
 
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#247
madisonears said:
I can't say with any certainty what effect the two sizes will have. My input cap is 0.68, and I think that is too small for a full range amp. The lowest bass gets a little sloppy, although it's still there and sounds okay. The only advantage of a smaller value cap, if not cost, is size. Both offer a low enough cut-off, but the larger cap will provide lower phase distortion. If your speakers (and music) really go down to 20hz, the larger cap is needed. I always intended my amp to be used only for mid and high frequencies, with a more powerful amp for bass, so a smaller cap means nothing significant is distorted. When run full range, they suffer somewhat on organ and lowest bass notes.

Peace,
Tom E
Click to expand...
The cutoff filter will be established only by the size of the cap and the input impedance. 0.68uF is small only if the input impedance is relatively small. Let's look at this example:
With this 100k input impedance amp, a 1uF cap will cut at 1,6Hz
With a 50k input impedance amp, a 2uF cap will cut at 1,6Hz
With a 25k input impedance amp, a 4uF cap will cut at 1,6Hz....
and so...
So a capacitor seeming big or small only depends of the amplifier's impedance. You can deduce that high impedance amps are more affordable considering the price/size of the input cap 😀

I have made a closer look comparison between 0.68, 1 and 2.2uF in the attached files. There are clear differences in phase between 0.68 and 2.2uF at 20Hz and above.

Regi
 

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#252
I think the easiest way for me to do this is to start a tiny online webcart so you guys can configure your order on it. It will only run me 9.99 for one month and its super easy to connect to my paypal. This way I dont have to configure each individual paypal invoice, you guys will do that by selecting how many kits or boards or LDRs you want. I will shut the shop down once we are done with this. This will NOT be on my Build An Amp . I will make it something like www.myrefcgroupbuy.com
Will let you all know the site this evening.
Shipping in the states will be $10.70. This kit will never fit in a small flat rate box. I went to the post office with some parts in a box that are similar to the kit size/weight and it was $7.60 from here (Texas) to Michigan (random choice). The medium flat rate box will allow more than 2 stereo kits easily and transformers as well I can use one size box and take care of all of you.
International: I priced the same box going to Australia and it was $13. I will set international shipping at $13 for one stereo kit and $5 more for a second stereo kit. I think that will cover all scenarios except for jtktam who wants 8 kits. I will do a special invoice for that one.
Pricing for a single channel is $63.45 so a stereo kit is 126.90 without shipping. I think we did well considering the Black Gate cap and upsizing the Obbligatto.
IF YOU WANT TO CHANGE YOUR ORDER _ _ Please please do it now.
Uriah
 
#254
Dang dude. Price is good but I thought we had a bit more time out 'til April 8.

Thinking I had some time I bought some drivers and have to deal with the monthly nut on April 1 and then see what's available. I changed my order to 2sets of boards for now for sure.

For the kits I have to check the final damage on my monthly commitments on the first of the month and see what's available after that. I should have room without stress but I cannot absolutely say for sure until then. Hence the change, for now.
 
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