ImPasse Preamplifier - Page 54 - diyAudio
Go Back   Home > Forums > Amplifiers > Pass Labs

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
Reply
 
Thread Tools Search this Thread
Old 5th May 2012, 12:27 PM   #531
diyAudio Member
 
luvdunhill's Avatar
 
Join Date: Jul 2006
SY, what cutoff frequency would you shoot for when choosing a capacitor before the 10K input impedance of the Impasse?

I should add the source is a phono preamp that has a rumble filter (simple RC).
  Reply With Quote
Old 6th November 2012, 01:58 PM   #532
diyAudio Member
 
luvdunhill's Avatar
 
Join Date: Jul 2006
quick question for SY and the others that frequent this thread.

I recently built some small subs to add to my full range speakers. My chain at the moment a digital source with 4V RMS output from its balanced output (238 output impedance on the balanced outputs), to my Impasse preamp to a pair of balanced bridged F4 (0dB gain) set to 200K input impedance per leg. This is connected to my full range speakers. For analog I have a .24mV MC cartridge, 76dB gain balanced output phono with 300 ohm output impedance. My second amp that I have to use as a bass amp, is balanced input as well, 100K input impedance with 20dB gain.

My plans are to construct a active crossover that would live after the Impasse, have the ability to attenuate the signal, with an appropriate buffer. I have it all drawn up and am playing with a discrete opamp to use in the circuit and getting that ready to go. The issue is, my time is disappearing for the year and I'd love to enjoy adding the subs sooner than later.

So, suggestions? Would something like a Behringer CX2310 fit the bill? or a single box with a PLLXO in it? Quick and dirty would be great.
  Reply With Quote
Old 8th November 2012, 04:12 PM   #533
diyAudio Member
 
luvdunhill's Avatar
 
Join Date: Jul 2006
I think the only question is what is the maximum input the CX2310 can take. Otherwise, I could put it before my Impasse, but then the volume control there doesn't scale both speakers...
  Reply With Quote
Old 8th November 2012, 04:30 PM   #534
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Marc, sorry I didn't see this before.

I'd aim for a 2Hz rolloff (one decade below lowest frequency of interest). Quick and dirty, I'd throw together a diff input opamp circuit with adjustable gain for the subs, run it off the output of the ImPasse, use the opamp circuit's level to balance bass and treble, then leave it alone and use the ImPasse for a master volume control. Don't know the CX2310, but I've done something like that with a DCX2496, which ran into a 4 or 6 channel balanced pre.
__________________
You might be screaming "No, no, no" and all they hear is "Who wants cake?" Let me tell you something: They all do. They all want cake.- Wilford Brimley
  Reply With Quote
Old 8th November 2012, 05:33 PM   #535
diyAudio Member
 
luvdunhill's Avatar
 
Join Date: Jul 2006
ok. thanks! i found a used CX2310 on Ebay for $60 shipped so I'll try that first.

Other than clipping the input of the CX2310 (which I'm not sure will be a problem anyways), the input impedance is 50K and I have 0.47uF capacitors in the Impasse (as I set my F4 to 200K input impedance).
  Reply With Quote
Old 8th November 2012, 05:47 PM   #536
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
That gives you an f3 something under 7 Hz, which is probably fine.
__________________
You might be screaming "No, no, no" and all they hear is "Who wants cake?" Let me tell you something: They all do. They all want cake.- Wilford Brimley
  Reply With Quote
Old 19th November 2012, 02:43 AM   #537
diyAudio Member
 
luvdunhill's Avatar
 
Join Date: Jul 2006
oh boy, this CX2310 looks like it will work. I need to fix up some more XLR cables in order to get both the bass and treble amp working.

One thing I'd like that I cannot get with this, is the high pass to not be crossed over, and only crossover the bass amp. I could do something strange, like use an XLR splitter on the input and connect that straight to the full range amp though, but I'm not sure what the consequences of that would be. For now though, I'll be happy just to play with this setup.

Oh and I also got a JAN-CHY-5692 to play with as well
  Reply With Quote
Old 20th January 2013, 03:08 PM   #538
6L6 is online now 6L6  United States
diyAudio Member
 
6L6's Avatar
 
Join Date: Oct 2010
Location: Denver, Colorado
A couple of questions, good sirs,

Can the inputs be both balanced and single ended, or do you have to choose one or the other?

Is the gain the same when using the output single-ended? (I'm only building one F4 to begin...)
  Reply With Quote
Old 29th March 2013, 04:54 PM   #539
6L6 is online now 6L6  United States
diyAudio Member
 
6L6's Avatar
 
Join Date: Oct 2010
Location: Denver, Colorado
Ordered the PCBs and Transformers from Jack, still rummaging through my
junk box, ahem, collection of various parts, to see what I can use.

Is there anything particularly important other than the CCS adjust resistor and the resistors in the split-load inverter?
  Reply With Quote
Old 29th March 2013, 05:55 PM   #540
diyAudio Member
 
jackinnj's Avatar
 
Join Date: Apr 2002
Location: Llanddewi Brefi, NJ
I can provide the following components for the Impasse -- if there's enough interest I can also get the input transformers (although they often take weeks.)

C1 2 Not used See Text
C2,5 4 100nF 630V Polypropylene
C3,C4 4 470nF 400V Polypropylene
D1,D2 4 Red LED, 1.7V Drop
NE1 2 NE2 Neon Lamp
P1 1 100K ALPS Dual Audio Taper
PCB 1 Printed Circuit Board
Q1,2 4 DN2540N5 Depletion MOSFET
R1 2 18K 1/4W Metal Film See Text
R11,12 4 15K 1W Matched to 0.1% 2 pairs
R2,9,13,14 8 1M 1/4W CMF55 Metal Film
R3,10 4 1K 1/4W CMF55 Metal Film
R4 2 12k5 2W Wirewound or Film
R5 2 300R 1/4W CMF55
R5a 2 2.7K 1/4W CMF55 Metal Film
R6,7 4 120R 1/4W Metal Film
R8 2 680K 1W Metal Film
S1 1 2 Pole, 5 Position Selector Switch
Misc 6 Molex 0.100 Inch Pin Headers
Misc 4 Nylon Spacers with nuts
Misc 2 Tube Sockets


And the following for the Impasse Maida Power Supply:
C1 1uF/600V PP
C2,3 100uF/450V
C4 47uF/450V
C9 10uF/100V
D101,102 UF4007
D103 12V 1W Zener
IC1 LM317 Regulator
PCB Printed Ckt Board
R1,2 47R 1/2W
R3 470R 1W
R4 1K 1W
R5 20K 1/4W
R6 100R 1W
R7 47R
R8/13 28K/1W
R9 200R 1/2W
R10 4.7R/0.25W
R11 270K/0.5W
R12 47K
U2 TIP50 Transistor
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Why do you need a preamplifier? globalweb Solid State 54 14th October 2007 04:47 PM
Mic PreAmplifier Ayne Solid State 4 13th April 2007 03:18 AM
Preamplifier aguantesoda Solid State 24 8th September 2006 02:39 PM
Preamplifier DIY Angel Puerto Solid State 13 20th July 2005 08:53 PM


New To Site? Need Help?

All times are GMT. The time now is 06:14 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2