With a 100k input impedance, 1uF will produce a -3db rolloff at 1.59Hz, while 2.2uF will do at 0.72Hz. Both low enough to not reduce audible frecuencies.
But, what about phase distortion?
RC Filter Weakness 2: Phase Distortion:
Input Capacitors for Headphone Amps
In theory, is goes down as cutoff frecuency goes down.
But, what about phase distortion?
RC Filter Weakness 2: Phase Distortion:
Input Capacitors for Headphone Amps
In theory, is goes down as cutoff frecuency goes down.
Folks,
As soon as I get comment from Tom and Dario on 1uf vs 2.2uf I can go through my numbers once more and give a final price. I think I can send Paypal invoices tomorrow.
Regi, nice information. Makes me feel positive that either cap is a good choice. The guy does a great explanation on his site and provides relevant links.
Uriah
As soon as I get comment from Tom and Dario on 1uf vs 2.2uf I can go through my numbers once more and give a final price. I think I can send Paypal invoices tomorrow.
Regi, nice information. Makes me feel positive that either cap is a good choice. The guy does a great explanation on his site and provides relevant links.
Uriah
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.
I need to make ones later more focused in 20Hz and above, to see better the differences.
Attachments
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
Peace,
Tom E
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WOW, I actually remember reading that article in print when it came out.. Picking Capacitors - Walter G. Jung and Richard Marsh
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
Attachments
Yes, one only needs to look at the RC time constants of the Lopass and Hipass filters.
we do it in radio 50us and 75us, in RIAA 75us, 318ms, etc
Awesome contribution guys! Really good information. Regi thanks so much for the simulations. The difference between .68 and 1 is pretty small it seems but the advantage of 2.2uf seems to be worth the price difference.
Okay my mind is set. 2.2uf.
I will try to finalize pricing now. Back to the spreadsheets!
Uriah
Okay my mind is set. 2.2uf.
I will try to finalize pricing now. Back to the spreadsheets!
Uriah
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
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
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.
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.
I'm currently looking for a suitable enclosure. Something inexpensive, made of metal. I am going with one case for both amps, or two monoblocks.
But I need to know the size to fit the amp; what are the exact dimensions of an assembled MyRef_C, without the standoffs?
Do you know any good place to order a not expensive case?
Thanks in advance
But I need to know the size to fit the amp; what are the exact dimensions of an assembled MyRef_C, without the standoffs?
Do you know any good place to order a not expensive case?
Thanks in advance
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