diyAudio - Blog Entries
Go Back   Home > Forums > Blogs
Home Forums Rules Articles diyAudio Store Gallery Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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
Old

Progress so far

Posted 6th January 2012 at 01:02 PM by rjm
Updated 7th January 2012 at 03:00 AM by rjm

The first stage is getting the power supply installed and running. That's the little board by the transformer, which just has the diodes, main filter capacitors, and isolation resistors on the voltage rails. The case top lid is transparent plexiglass, so the internals are lit by three white LEDs to show off, and light the control labels, which are printed on the top lid rather than the front and back sides of the case.

You'll notice I have followed the instructions and removed the plastic covers on the electrolytic capacitors.

For the record I do think they sound better that way, I just normally can't be bothered as, for example, my phonoclone 3 boards have 28 of them and I consider the exposed metal surfaces a bit of a safety issue as well.
Attached Thumbnails
Click image for larger version

Name:	DSC_2878 1280.jpg
Views:	583
Size:	337.9 KB
ID:	556  
rjm's Avatar
rjm
diyAudio Member
Views 778 Comments 2 rjm is offline
Old

47 Labs 0247 unboxing, part deux

Posted 5th January 2012 at 11:29 AM by rjm

My kit was missing the amplifier circuit boards! So many other neat stuff distracted me from this vital fact!

So far I've wired the AC power line components, transformer, and the power supply board. It's slow progress, mainly for wanting to be sure of getting it right the first time. It's dense and fiddly, desoldering stuff in there to fix a ****-up would not be pleasant work at all.
rjm's Avatar
rjm
diyAudio Member
Views 673 Comments 0 rjm is offline
Old

Five-times-bandwidth

Posted 3rd January 2012 at 05:44 PM by rjm

If we accept that conventional wisdom that the audio bandwidth extends from 20 Hz to 20 kHz, a good rule of thumb for the f(-3 dB) high and low cutoff points of the frequency response of each audio circuit element is 5x the bandwidth, or 4 Hz to 100 kHz. In practice most designs tend to shift that range a little to the higher frequencies, so perhaps 5 Hz - 200 kHz, or 4 - 250 kHz.

Personally I "tune" my circuits to 4 Hz. That is, the time constants are adjusted to about 4 ms. Capacitance is usually cheap enough to go even longer, but the influence on sonics is typically net negative.

The high frequency side is more interesting, since many circuit elements naturally run into the megahertz range, the the question is do you actively try to prevent that, and if so, where and how?

The biggest issue is bypassing: a small value electrolytic (100 uF) is probably fine up to 100 kHz or so, but quite useless at 2 Mhz. The textbook solution is...
rjm's Avatar
rjm
diyAudio Member
Views 648 Comments 0 rjm is offline
Old

How much power is enough for an amp?

Posted 2nd January 2012 at 03:09 AM by alexcp (My DIY projects)

Bruno Putzeys posted:
About power ratings, well... Normal "critical listening" levels hover around a long-term average of 85db SPL at the listening position. If we're assuming uncorrelated signals (rather inaccurate assumption but it'll do for the purpose) that is 82dB SPL for each speaker alone. Crudely calculating back from a 2m listening distance to the 1m standard measuring distance that's 88dBSPL, one speaker, one meter. It's not unusual for speakers to have an efficiency of 88dB/1w/1m so 1W is roughly the required amplifier power.

The current crop of unlistenable hypersquashed pop music has a peak to average range of around 4dB. So all it takes to reproduce pop at a reasonable level without clipping is a 4dBW (2.5W) rated amp.
Before the loudness war got into swing (say until the early 90's) peak-to-average ranges up to 14dB could be found in mainstream music. To play Sultans of Swing at the same average level requires an amp rated at 14dBW
...
alexcp's Avatar
diyAudio Member
Posted in Speakers
Views 1361 Comments 0 alexcp is offline
Old

Improved current source

Posted 2nd January 2012 at 01:18 AM by klewis

http://www.diyaudio.com/forums/solid...urce-sink.html
klewis's Avatar
diyAudio Member
Posted in Uncategorized
Views 733 Comments 0 klewis is offline
Old

Solid state relay

Posted 30th December 2011 at 11:55 PM by klewis
Updated 3rd January 2012 at 03:43 PM by klewis

Fets: http://www.diyaudio.com/forums/solid...relays-17.html

Pavel's Scheme http://www.diyaudio.com/forums/solid...ml#post2835407
Also see post #340, increase R1 to 100k and C3&4 to 47uf
recommendation for mosfets: #314
In general, you are seeking for a MOSFET with very high Vdsmax, very low Rdson and very high Idmax. Regarding Vdsmax, it must be higher than the sum of positive and negative supply rail voltage, and the output should be provided by clamping diodes connected to supply rails, reverse polarized. My tips are

Type Vdsmax Rdson Idmax
IRFB1227 200V 0.0197ohm 130A
IRFP90N20D 200V 0.023ohm 94A
IRF3710ZG 100V 0.018ohm 59A (too low Vdsmax to me)
IRFS59N10D 100V 0.025ohm 59A (too low Vdsmax to me)
klewis's Avatar
diyAudio Member
Posted in Uncategorized
Views 1118 Comments 0 klewis is offline
Old

Mk3: How to do this...???

Posted 30th December 2011 at 09:45 PM by cberger
Updated 30th December 2011 at 09:47 PM by cberger

hmmm...the plan calls for 5 degree angles for some cuts. How to do those? Just sand it away?
diyAudio Member
Posted in Mk3
Views 408 Comments 0 cberger is offline
Old

it's xmas time

Posted 30th December 2011 at 09:30 PM by cberger
Updated 30th December 2011 at 09:48 PM by cberger

So I finally decided to build my first set of speakers: The Frugel-Horn mk3.
Reasons:
  1. Fairly high WAF
  2. Looks good (see point 1)
  3. Can be built with "cheap" components
  4. Reasonably challenging wood work
  5. full range driver = no crossover needed
Most of the stuff I ordered so far I ordered based on recommendations / suggestions from the people here like Planet10 Dave, ChrisB and others.

Some stuff that I ordered on Monday arrived already :-)
2 CHR-70 Drivers
CSS UltraTouch insulation

Just now I ordered some terminals, a circle jig (jasper #400), and Acousta stuff
diyAudio Member
Posted in Mk3
Views 309 Comments 0 cberger is offline
Old

Pass B1 buffer

Posted 26th December 2011 at 12:53 AM by klewis
Updated 26th December 2011 at 03:47 PM by klewis

Post #166 board layout
omron G6H2 12v relays
Motorized alps pot http://www.ebay.ie/itm/ws/eBayISAPI.dll?ViewItem&clk_rvr_id=300979180833&ite m=250467804650
Post #1062 for relays
Post 1031 cap tweak
klewis's Avatar
diyAudio Member
Posted in Uncategorized
Views 965 Comments 0 klewis is offline
Old

Tapped Horn

Posted 22nd December 2011 at 03:34 PM by DougL

Found this Discussion and resources:
http://www.cowanaudio.com/th.html
diyAudio Member
Posted in Uncategorized
Views 1143 Comments 1 DougL is offline
Hide this!Advertise here!

New To Site? Need Help?

All times are GMT. The time now is 02:10 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2016 DragonByte Technologies Ltd.
Copyright 1999-2016 diyAudio

Content Relevant URLs by vBSEO 3.3.2