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Old

Solid state relay

Posted 30th December 2011 at 10:55 PM by klewis
Updated 3rd January 2012 at 02:43 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)
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Old

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

Posted 30th December 2011 at 08:45 PM by cberger
Updated 30th December 2011 at 08:47 PM by cberger

hmmm...the plan calls for 5 degree angles for some cuts. How to do those? Just sand it away?
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Old

it's xmas time

Posted 30th December 2011 at 08:30 PM by cberger
Updated 30th December 2011 at 08:48 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
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Old

Pass B1 buffer

Posted 25th December 2011 at 11:53 PM by klewis
Updated 26th December 2011 at 02:47 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
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Old

Tapped Horn

Posted 22nd December 2011 at 02:34 PM by DougL

Found this Discussion and resources:
http://www.cowanaudio.com/th.html
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Old

47 Labs 0247 "Treasure" unboxing

Posted 21st December 2011 at 03:33 AM by rjm (RJM Audio Blog)
Updated 22nd December 2011 at 09:47 PM by rjm

It's here!

It came in a box the size of a small shoe box.

Curious, delightful mix of the mundane and the exotic, outwardly plain but clearly immense thought and effort has gone into the preparation.

The gorgeous hammertone finish, hand-matched transistors, and ultra-high quality machined volume/selector knobs are the little signs that immediately set it apart from the ordinary.
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Old

The cost of hi-end audio: is it worth it?

Posted 20th December 2011 at 05:16 AM by rjm (RJM Audio Blog)
Updated 20th December 2011 at 05:30 AM by rjm

Having recently actually bought some new (not used, not my own design, and relatively expensive) audio gear, and from 47 Labs no less, the following question has been occupying my thoughts of late:

How much would you pay to not have a component installed in the audio equipment you buy?

The traditional price scheme for audio equipment is [BOM-times-X], where BOM is the cost of the parts used to make it, and X is a multiple to cover fabrication and distribution costs, as well as profit for the various parties involved. My understanding is that for consumer audio "X" is about 4, though companies with strong brand recognition can get away with higher multiples. And do.

The basic problem is this: how much it costs to build and how good it sounds are not the same thing. There is some correlation: a large, high quality transformer is pretty much guaranteed to improve the sound quality, but for the rest, stuffing a pretty box with many cheap...
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Old

47 Labs "Treasure" 0247 shipping update

Posted 19th December 2011 at 11:19 PM by rjm (RJM Audio Blog)

Scheduled to be delivered tomorrow evening!
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Old

Zen V4-J

Posted 17th December 2011 at 01:12 PM by alexcp (My DIY projects)
Updated 12th May 2013 at 04:03 PM by alexcp

Now that Nelson Pass published the details of the JFET upgrade to First Watt F2 and that Newark sells power JFETs from Semisouth, there was no excuse not to upgrade my Zen V4 with the new active device.

I replaced Q1 (see the original schematic) with SJEP120R100A; increased R5 to 130 kohm to bias the JFET correctly with Vgs of approx. 1.5V; and reduced R8 to 22 ohm.

The measured result is a nice reduction in THD+N; attached are the graphs for THD+N @ 1W into 8 ohm vs frequency, before and after the upgrade. With IRFP044 as Q1, the distortion was mostly 2nd harmonic (at -65dB), plus some traces of the 3rd harmonic. With the JFET, it is still mostly 2nd harmonic, which is now at -80..85dB, with the 3rd below my measurement floor.

Subjectively, the improvement is remarkable! There is additional detail and depth of the scene.
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Old

Fascinating: SMT attenuator retrofitted into ALPs case

Posted 17th December 2011 at 02:08 AM by rjm (RJM Audio Blog)

http://www.icl.co.jp/audio/att.htm

Less than 3,000 yen, too. Pity it's only available as 100K types, but for tube amps this is a pretty handy little part to have around.
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