G'ay all, I suspect that this is well understood and appreciated by anyone involved in DIY (stereo) electronics construction, but despite being a long time DIYer myself it is something that I never properly appreciated.
As a result of a number of 'chance' incidents of late I've come to the realisation as verified by my simple test gear (a multimeter and a capacitance meter), that none of my DIY phono stages were particularly well 'matched', channel to channel.
I've spent the last couple of days finding and installing matched resistors and capacitors, and honestly what a difference it makes! I honestly don't think that I've heard and appreciated good stereo before!
Even things like record scratch and ticks and pops are much less audible as well, presumably through the effects of improved channel to channel 'balance'. The lesson is clear and I cannot stress it enough, 'match' those stereo channels! Regards, Felix.
As a result of a number of 'chance' incidents of late I've come to the realisation as verified by my simple test gear (a multimeter and a capacitance meter), that none of my DIY phono stages were particularly well 'matched', channel to channel.
I've spent the last couple of days finding and installing matched resistors and capacitors, and honestly what a difference it makes! I honestly don't think that I've heard and appreciated good stereo before!
Even things like record scratch and ticks and pops are much less audible as well, presumably through the effects of improved channel to channel 'balance'. The lesson is clear and I cannot stress it enough, 'match' those stereo channels! Regards, Felix.
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Welcome To The Club....
This is sort of old news, but relevant none the less.
You stated that you used a multimeter and cap meter.
Another very useful tool is a Distortion and Noise/Level meter.
With the input set to differential (transformer balanced) mode, any two same points in a stereo system can be compared/matched, and to very high precision.
Clarity, L/R imaging, depth imaging, image stability etc, etc.....everything improves with correct channel matching.
Dan.
G'day Felix.
This is sort of old news, but relevant none the less.
You stated that you used a multimeter and cap meter.
Another very useful tool is a Distortion and Noise/Level meter.
With the input set to differential (transformer balanced) mode, any two same points in a stereo system can be compared/matched, and to very high precision.
Clarity, L/R imaging, depth imaging, image stability etc, etc.....everything improves with correct channel matching.
Dan.
Useful Test Gear On the Cheap.....
The degree/depth of nulling will depend on the channel matching of this amplifier however.
Dan.
Any old standard stereo amp using the L and R inputs with one speaker connected between the two active outputs will function as a differential amplifier.
The degree/depth of nulling will depend on the channel matching of this amplifier however.
Dan.
How old is the phono stage in question ?
In days of old it was quite common to use 10% resistors and capacitors, these days there are much better components off the shelf.
Just replacing the resistors with 1% resistors won't cost you more than a few dollars.
Getting the capacitors closer together also shouldn't be a monumental task, here 2% components will be more than sufficient and again won't cost the earth.
In days of old it was quite common to use 10% resistors and capacitors, these days there are much better components off the shelf.
Just replacing the resistors with 1% resistors won't cost you more than a few dollars.
Getting the capacitors closer together also shouldn't be a monumental task, here 2% components will be more than sufficient and again won't cost the earth.
I've built at least a half-dozen RIAA stages in the last 10 years --- I learned to purchase the capacitors (from Mouser) about 25 at a time, and the resistors in packs of 100.
It is important to try and get the RIAA match between channels close. With 25 of the WIMA's I can usually get about ten matches. The matched pairs I didn't use for my own phono stage I packaged as kits for SY's "His Majesty's Noise". I was lucky to purchase a GenRad Digibridge when the internet bubble blew up 10+ years ago.
It is important to try and get the RIAA match between channels close. With 25 of the WIMA's I can usually get about ten matches. The matched pairs I didn't use for my own phono stage I packaged as kits for SY's "His Majesty's Noise". I was lucky to purchase a GenRad Digibridge when the internet bubble blew up 10+ years ago.
It's not just in the phono stage you need to match channels. Years ago, I built an analog low-level crossover to run a bi-amp system. A few weeks ago, I replaced it with DSP, done in an old PC. Yes, I used 1% resistors, yes, the best caps I could find.
The new crossover is far better at the perceived image and matching from top to bottom. Calculations don't have a tolerance range....
The new crossover is far better at the perceived image and matching from top to bottom. Calculations don't have a tolerance range....
what's with the phono stage people posting about lack of measuring capability?
if you have a conventional PC bought in the past decade you almost certainly already have 24/96 ADC/DAC in the HD sound chipset
of course "even" 16/48 is fine
and even poor motherboard systems deliver over 80 dB S/N + frequency accuracy, flatness, and low distortion performance
low frequency roll off, channel amplitude matching are the only points that need calibrating
low frequency roll off depending on DC blocking C values and load/source impedance
channel level matching needed if better than the 1-2% typical of ADC/ADC chips is needed
a few RCA/TRS couplers, attenuators, free software like Visual Analyzer, Audacity, Ltspice, SciLab for playing with .wav, creating, analyzing signals
quickest start to see the PC soundcard capabilities would probably be to use free RMAA and do a analog loopback measurement - do find the line jack input and or settings instead of mic in
if you have a conventional PC bought in the past decade you almost certainly already have 24/96 ADC/DAC in the HD sound chipset
of course "even" 16/48 is fine
and even poor motherboard systems deliver over 80 dB S/N + frequency accuracy, flatness, and low distortion performance
low frequency roll off, channel amplitude matching are the only points that need calibrating
low frequency roll off depending on DC blocking C values and load/source impedance
channel level matching needed if better than the 1-2% typical of ADC/ADC chips is needed
a few RCA/TRS couplers, attenuators, free software like Visual Analyzer, Audacity, Ltspice, SciLab for playing with .wav, creating, analyzing signals
quickest start to see the PC soundcard capabilities would probably be to use free RMAA and do a analog loopback measurement - do find the line jack input and or settings instead of mic in
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Completely agree on the subject. It's better to match resistors and caps between channels (although the actual value is important for a flat RIAA response); than just ordering the correct values. I usually order a bunch of resistors and caps, and measure the resistor and cap value @ 1kHz (I use a BK Precision 879b; best investment -ever-).
Also, it's handy to order parts which have low drift. You know the RIAA-curve will not be impacted when your stage warms up.
Also, due to this: never hold components when measuring them. It heats them up, skewing your results.
JCX makes a valid statement. I use Ableton Live with the Vacuumsound RIAA plug-in to playback the RMAA-file. It's a free plug-in that applies an inverse RIAA-curve, whilst lowering the sound level 20dB.
Any sound card will do to match your response. Although you shouldn't forget about correctly loading the signal
Also, it's handy to order parts which have low drift. You know the RIAA-curve will not be impacted when your stage warms up.
Also, due to this: never hold components when measuring them. It heats them up, skewing your results.
JCX makes a valid statement. I use Ableton Live with the Vacuumsound RIAA plug-in to playback the RMAA-file. It's a free plug-in that applies an inverse RIAA-curve, whilst lowering the sound level 20dB.
Any sound card will do to match your response. Although you shouldn't forget about correctly loading the signal
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