Amplifiers:Pass Labs Amplifiers
Name | F5 Power Amplifier | |
Type | Solid State, Push/Pull | |
Application | < | |
Class | A, A/B, | |
Approx Cost | $200-500? | |
Designer | Nelson Pass | |
Thread | http://www.diyaudio.com/forums/pass-...amplifier.html |
The Project
Introduction
Read this first
Goals
What were some of your goals with the design of the amp? In the end, did you achieve them? If not, where did the design fall short of your expectations?
examples: I wanted to create a class A amp that produced THD 0.00001% at 1KHz but I only achieved 0.01%
examples: I wanted to create a class A amp that produced THD 0.00001% at 1KHz but I only achieved 0.01%
Specifications
Name | Description |
Volatge Gain | 15.3 dB |
Bandwidth | Value |
Phase | Value |
Sensitivity | 8 Ohm: Value, 4 Ohm: Value |
S/N Ratio | ~60 uV unweighted, 20-20 KHz |
Rated Consumption | 180W |
Idle Consumption | 180W |
Harmonic Distortion | Distortion @ 1 watt .001% to .005% @ 1 KHz |
Harmonic Spectrum | FFT plot/plots |
Square/Step response | Oscilloscope Trace |
Stability | Phase margin + scope traces into capacitive loads |
Output configurations | Can it be bridged? Parallel drive? |
Output Impedance | Value or plot/plots |
Schematic/Blueprint
Please attach schematics to this wiki page. You can then use the tag to display them inline. Please don't be afraid to attach Gerber files to the page as well.
Note: There is a bug in the wiki right now where you can't add attachments to a wiki after 30 minutes.
Note: There is a bug in the wiki right now where you can't add attachments to a wiki after 30 minutes.
Bill of Materials
PCB Availibility
http://www.diyaudio.com/store/pcb-ba...cb-set-45.html
Also Group Buys listed further down on this page.
Power Transformers
Either list them in this section or attach a file to the page that people can download.
Note: If this project uses other projects as components (maybe this is a full build and uses an amplifier and PSU from other projects, please list them here).
http://www.diyaudio.com/store/pcb-ba...cb-set-45.html
Also Group Buys listed further down on this page.
Power Transformers
Either list them in this section or attach a file to the page that people can download.
Note: If this project uses other projects as components (maybe this is a full build and uses an amplifier and PSU from other projects, please list them here).
Simulations and Analysis
Embed the images for your simulations here along with descriptions for each of them so people know what you're talking about.
Construction (Steps / Tips / Notes)
This section is incomplete and will be a bit messy unyil I get all information into it.
GB F5 Guide (pcb version 2)
http://www.diyaudio.com/forums/blogs...version-2.html
F5 components, parts you use
http://www.diyaudio.com/forums/pass-...s-you-use.html
GB F5 Guide (pcb version 2)
http://www.diyaudio.com/forums/blogs...version-2.html
F5 components, parts you use
http://www.diyaudio.com/forums/pass-...s-you-use.html
Project Initial Setup
Suggested start up should have the PS disconnected from the amp boards.
Also use a variac or dim bulb tester or both.
Variac
http://en.wikipedia.org/wiki/Autotransformer
dim bulb testers
http://www.diyaudio.com/forums/power...lb-tester.html
Bias Setting(thanks to ZM)
dial both pots to 0 ohms ( check with ohmmeter )
place one voltmeter across PSU caps ( best between + and - of PSU) to observe max voltage of PSU
place one voltmeter at output - to observe offset
place one voltmeter across one source resistors(R11 or R12) of output mosfets ; it doesn't matter which one .
for test - slowly dial up Variac ( presuming that you have one , as man with many skills) up to full mains voltage , observing voltage at PSU ....... thinking about max cap voltage ( 25V as in FW ? ) , because with 0 Iq PSU is unloaded and voltage is maxed
if nothing is smelling
- leave Variac at full mains ;
what's important - Iq must be very low , offset is irrelevant in this moment .
now turn one pot one turn ( assuming that you have multiturns )
then turn other pot one turn
observe Iq and offset
proceed one then second pot , again just one turn
observe Iq and offset
again one turn + one turn
now you are probably in range when you can see which pot is pulling offset in right direction - to 0 .
proceed iteratively with pots , while you set - say - 75% of desired Iq and zero offset
now - put lid on box and let it cook for a while - until yo get thermal equilibrium on heatsinks
it's best to use wire/clips to leave those voltmeters in place ;
open the lid , up bias to - say - 90% of desired one ,while maintaining offset
put lid on , let it cook
check ;
if all is OK - move voltmeters for Iq and offset to other channel and repeat procedure
use it few days at 90% of desired bias , then check and set to 100%
remember - temp. equilibrium with lid on is important
simple , isn't it ?
Also use a variac or dim bulb tester or both.
Variac
http://en.wikipedia.org/wiki/Autotransformer
dim bulb testers
http://www.diyaudio.com/forums/power...lb-tester.html
Bias Setting(thanks to ZM)
dial both pots to 0 ohms ( check with ohmmeter )
place one voltmeter across PSU caps ( best between + and - of PSU) to observe max voltage of PSU
place one voltmeter at output - to observe offset
place one voltmeter across one source resistors(R11 or R12) of output mosfets ; it doesn't matter which one .
for test - slowly dial up Variac ( presuming that you have one , as man with many skills) up to full mains voltage , observing voltage at PSU ....... thinking about max cap voltage ( 25V as in FW ? ) , because with 0 Iq PSU is unloaded and voltage is maxed
if nothing is smelling

what's important - Iq must be very low , offset is irrelevant in this moment .
now turn one pot one turn ( assuming that you have multiturns )
then turn other pot one turn
observe Iq and offset
proceed one then second pot , again just one turn
observe Iq and offset
again one turn + one turn
now you are probably in range when you can see which pot is pulling offset in right direction - to 0 .
proceed iteratively with pots , while you set - say - 75% of desired Iq and zero offset
now - put lid on box and let it cook for a while - until yo get thermal equilibrium on heatsinks
it's best to use wire/clips to leave those voltmeters in place ;
open the lid , up bias to - say - 90% of desired one ,while maintaining offset
put lid on , let it cook
check ;
if all is OK - move voltmeters for Iq and offset to other channel and repeat procedure
use it few days at 90% of desired bias , then check and set to 100%
remember - temp. equilibrium with lid on is important
simple , isn't it ?
Project Modifications
Do you have some small modifications to suggest for the project that could improve it? Please list them and tell us why they improve the design. If this is discussed in a thread, please link the thread URL here....
Modification 1
Cross the streams!
Modification 2
Install a flux capacitor!
Reviews
Review 1
F5 Listening Impressions & Discussion
http://www.diyaudio.com/forums/pass-labs/155599-f5-listening-impressions-discussion.html
http://www.diyaudio.com/forums/pass-labs/155599-f5-listening-impressions-discussion.html
Review 2
Duuuude.....
Build Threads
F5 Build by 6L6
http://www.diyaudio.com/forums/pass-labs/182723-how-build-f5.html
F5 Build by CanAm Man
http://www.diyaudio.com/forums/pass-labs/183941-another-f5-build-beautiful-music-different-drummer.html
Planning an F5 build - some beginner questions
http://www.diyaudio.com/forums/pass-labs/137955-planning-f5-build-some-beginner-questions.html
Have you built this project? If so, please add the URL to the thread that you started to show off your build.
Related Group Buys
- CvillerGroupBuy:http://www.diyaudio.com/forums/group...gb-f5-pcb.html
- Peter Daniel Group Buy http://www.diyaudio.com/forums/group...group-buy.html
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