Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › Are these "upgrades" worthwhile on a 4-channel Sigma / Beta 22?
New Posts  All Forums:Forum Nav:

Are these "upgrades" worthwhile on a 4-channel Sigma / Beta 22?

post #1 of 6
Thread Starter 
Hi,

I am considering having a 4-channel Sigma/Beta 22 built to use with my HD800s. There are a number of upgrades available. I wanted ask this more technically oriented forum if they feel any of these are worthwhile:

1. Additional Sigma 22 power supply (comes w/ additional 80VA toroidal transformer)
2. Goldpoint stepped attenuator upgrade (quad channel)
3. Power supply upgrade: 100VA transformer, 6800uF x 2 filtering capacitors, ultrafast HEXFRED diodes

A) none of these
b) better attenuator over stock Alps potentiometer
c) add a second PSU
d) upgrade the transformer(s)

Which of these or combinations of these is worthwhile and why?

Thanks,

Bob
post #2 of 6

a single b22 board can drive the HD800 to 126 dB SPL clipping level

 

a dual monoblock build - 2 completely isolated R,L channels with independent power supplies would be the cheapest "ultimate" configuration

 

I would use a EI split bobbin double reinforced insulation power xmfr in each supply to be able to float the amps - better power line isolation than toroidal

 

 

by wiring "balanced" to the headphone you eliminate crosstalk from common gnd on the TRS

 

going 4-board (pseudo)balanced really isn't buying more "quality" beyond a dual mono setup for these cans


Edited by jcx - 10/4/12 at 9:28am
post #3 of 6
Thread Starter 
Quote:
Originally Posted by jcx View Post

a single b22 board can drive the HD800 to 126 dB SPL clipping level

 

a dual monoblock build - 2 completely isolated R,L channels with independent power supplies would be the cheapest "ultimate" configuration

 

I would use a EI split bobbin double reinforced insulation power xmfr in each supply to be able to float the amps - better power line isolation than toroidal

 

 

by wiring "balanced" to the headphone you eliminate crosstalk from common gnd on the TRS

 

going 4-board (pseudo)balanced really isn't buying more "quality" beyond a dual mono setup for these cans

Thanks for your response.  May I ask you to "dumb" down your recommendation?  Is this a 3-channel configuration instead of a 4-channel?

 

Appreciated,

post #4 of 6
no, as he said, its only a 2 channel, but using isolated transformers to eliminate crosstalk between them and wiring the headphones with a 4 conductor connector (4 pin XLR or similar) to elliminate the shared ground connection on the TRS/phone connector

in other news, yay the spellchecker is working in firefox again!
post #5 of 6

if you really need analog volume control, have balanced source, then TVC may give real advantages - and have great audiophile reputation

 

the high price of quality 24 tap audio input transformer attenuator and switch would be offset somewhat by recognizing the savings with only 2 b22 boards used for single ended output really isn't a "compromise" - it is as good as it gets for HD800 Z, sensitivity

 

(one source with pricing) http://www.sowter.co.uk/cgi-bin/sh000001.pl?REFPAGE=http%3a%2f%2fwww%2esowter%2eco%2euk%2facatalog%2fsearch%2ehtml&WD=9985&PN=SOWTER_TRANSFORMERS_ATTENUATORS_13%2ehtml%23a150#a150

 

$k stand alone TVC "passive preamps" could also be used - could skip the b22 input atten all together

 

a quality audio input transformer without taps is still another possible upgrade, can then use SE or Bal source and only needs stereo attenuator in front of the amps

 

 

but the lowest cost solution is to use modern digital volume control - recent generation sw can recognize/be told that the DAC is 24 bit and will give "perfect" attenuation performance limited by the analog electronics noise floor - the "lost bits" objection to digital volume control is way past its "use by" date


Edited by jcx - 10/5/12 at 8:55am
post #6 of 6
Quote:
Originally Posted by jcx View Post

but the lowest cost solution is to use modern digital volume control - recent generation sw can recognize/be told that the DAC is 24 bit and will give "perfect" attenuation performance limited by the analog electronics noise floor - the "lost bits" objection to digital volume control is way past its "use by" date

I know, but it just wont die will it? rolleyes.gif the whole 'lost bits' thing just keeps on persisting, if I had a dollar for each time ive had to explain/argue that it simply doesnt get any better or cheaper these days, I would be a billionaire (millionaire is so 90's) not only that, perfect channel matching all the way through the range with as many channels as you want/need ganged or individually, free remote control with an ipad etc etc

you still have to make sure you have sensible gain structure and digital glitches are unfortunately not attenuated, so ytou have to make sure your setup is clean, but with that taken care of its perfect. you can even use a single platter stepped attenuator to control the control voltage if you want that audiophile tactile feel. i'm actually looking at grabbing one of these Elma E50 to control mine and other functions (has integrated push button), control as gang or individually for multichannel (digital crossover) duties on a new improved MCU for my system

http://www.elma.com/Admin/ProductionFiles//ProductTypeFile/380/English/10%20Magneto-Optical%20Encoder%20Type%20E50.pdf

New Posts  All Forums:Forum Nav:
  Return Home
Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › Are these "upgrades" worthwhile on a 4-channel Sigma / Beta 22?