|
|||||||
| Home | Forums | Rules | Articles | Store | Gallery | Blogs | Register | Donations | FAQ | Calendar | Search | Today's Posts | Mark Forums Read | Search |
| Pass Labs This forum is dedicated to Pass Labs discussion. |
|
|
Please consider donating to help us continue to serve you.
Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving |
![]() |
|
|
Thread Tools | Search this Thread |
|
|
#1 |
|
diyAudio Member
Join Date: May 2004
Location: houston
|
proceeding under the premise that there is no perfect part....
i was looking at the schematics of an older nelson pass design that i own (adcom 585) and i see that in addition to a slow start circuit, he also has wired a coupling capacitor (4.7uf) and resistor (1k) as the first things the input signal sees. now i understand that the coupling cap is there to remove any DC that a preamp might send. but given the soft start circuit (and assuming good turn-on procedure: preamp 1st, amp 2nd), should this C-R network even be in the signal path? seems like a great way to lose transparency w/ no benefit to me... also, given the coupling cap, i also see that the design has 4 dc-rail fuses on the output stage (which, i would assume, would blow prior to substantial DC being output to the speakers). again, how redundant is all this? (i'm apt to leave the fuses, as i can get nice silver plated fuses that sound fast & nice, but remove the coupling cap, as i think that any cap will impact the sound more than the DC rail fuses will). i'd like to pull the cap as i assume this will improve transparency, but i'd love some advice on if i should pull the cap, the C&R, or neither. (as i'm not sure the purpose of the resistor in this network). (and i can live w/ the risk of DC output from the preamp, as i'll always turn it on first.) thoughts? thanks! rhyno |
|
|
|
#2 |
|
The one and only
|
I don't recall designing a 585. More likely it was a modified
version of an earlier circuit I did, however some resistance in series with the input is generally a good idea to prevent oscillation in a system, either from a preamp that doesn't want to look at the base of a transistor directly, or vice versa, or to help reduce the possibility of pickup from the output of the amp back to the input. |
|
|
|
#3 |
|
diyAudio Member
Join Date: May 2004
Location: houston
|
thanks for the advice.
given the requirement of the resistor, is it still a safe assumption that the coupling cap can go? best rhyno |
|
![]() |
| Thread Tools | Search this Thread |
|
|
Similar Threads
|
||||
| Thread | Thread Starter | Forum | Replies | Last Post |
| Adcom GFA-555 | claiborne | Solid State | 8 | 27th September 2007 10:20 AM |
| Trouble with speaker protection circuit (Randy Slone's circuit) | whalefat | Solid State | 3 | 13th April 2005 10:13 AM |
| Adcom GFA-585 went bad - calling Adcom experts | hangguy | Solid State | 14 | 24th December 2004 08:09 PM |
| Is Adcom GFP750 circuit same as BZLS or Aleph L? | KT | Pass Labs | 14 | 6th October 2004 04:04 AM |
| Solution to redundancy | PassFan | Everything Else | 1 | 21st January 2002 03:02 AM |
| New To Site? | Need Help? |