This seems like an upgrade:
EDCOR - MXLcs Series
It comes shielded, available in a 1:5 ratio
Mechanical drawing
EDCOR - MXLcs Series
It comes shielded, available in a 1:5 ratio
Mechanical drawing
> I also made a 'fast and dirty' measurement with my simple PC-oszi.
> I have sent a 1kHz - sinus at circa 0.6V through that little thingie...
Before you do a FFT with the BFB, first do one with the scope and the func gen itself.
Just connect them together directly.
That tells you how good your equipment is, before inserting the BFB.
Patrick
> I have sent a 1kHz - sinus at circa 0.6V through that little thingie...
Before you do a FFT with the BFB, first do one with the scope and the func gen itself.
Just connect them together directly.
That tells you how good your equipment is, before inserting the BFB.
Patrick
Here are links to some measurement results at different levels and loads of the Calvin Buffer from which the BFB originates, plus some remarks.
So you have some reference.
Preamp-Buffers - simple idea
Preamp-Buffers - simple idea
Preamp-Buffers - simple idea
Preamp-Buffers - simple idea
Preamp-Buffers - simple idea
Patrick
So you have some reference.
Preamp-Buffers - simple idea
Preamp-Buffers - simple idea
Preamp-Buffers - simple idea
Preamp-Buffers - simple idea
Preamp-Buffers - simple idea
Patrick
Mark Johnson Opamp Evaluation Round 2
Mark Johnson kindly sent me a second set of evaluation opamps which I was very happy to listen to and review immediately upon receipt. Please refer to post #4603 The diyAudio First Watt M2x for my evaluation of the first set of opamps. That post includes system and program material information and a description of my evaluation criteria.
These 3 opamps were coded Silver, Yellow and White. White was the only dual opamp, thus requiring placement in the "dual" IPS7 socket. All the others were singles. Again, my references were the OPA1612A installed in the "dual" socket of the IPS7 card, and secondarily, the IPS6 daughter card.
The new evaluation opamps, in order of preference were:
#1 YELLOW - T5, D4, B5; Yes, this opamp edged out my long time OPA1612A favorite. It's the equal of the IPS6 card (T4, D5, B5) with a slightly different emphasis. Very smooth and clear, with pretty good imaging. Excellent bass instrument and percussive definition. Superior for both male and female vocals. Definite smile factor. I'm tempted give it all 5's but the thing is, it's really a toss up between YELLOW, OPA1612 and IPS6 card. They all have their strengths.
#2 SILVER - T4, D3, B4; Slightly bright but not harsh. Detailed but with a flat, 2D, sound character. Forward sounding vocals. Austere sound with a decidedly soft bass character. A bit exciting but overall, no smiles.
#3 WHITE - T4, D4, B3; Clear but with a slight harshness, mostly apparent on female vocals. Appears to lack low bass but that might just be an abundance of highs. Moderate depth to the sound stage but somehow not exciting. No smiles.
If you haven't figured it out by now, I like a slightly lush tonally balanced sound where the distortion character favors the 2nd harmonic. It must provide a sound stage that offers good instrument separation and depth. The fine details and dynamic range can't get lost in either the noise floor or the distortion. The YELLOW opamp meets that criteria, falling a bit short only in it's ability to provide a fully 3D sound stage.
Some idle speculation:
I'm just guessing here but I think YELLOW maybe is saved by a good (not excessive) slew rate, low THD and low noise. Comparing it to the OPA1612, I may be hearing the difference between the OPA1612's bipolar inputs and either JFET or FET inputs in the YELLOW device. I won't know for sure until Mark reveals the opamp device identifications.
Mark Johnson kindly sent me a second set of evaluation opamps which I was very happy to listen to and review immediately upon receipt. Please refer to post #4603 The diyAudio First Watt M2x for my evaluation of the first set of opamps. That post includes system and program material information and a description of my evaluation criteria.
These 3 opamps were coded Silver, Yellow and White. White was the only dual opamp, thus requiring placement in the "dual" IPS7 socket. All the others were singles. Again, my references were the OPA1612A installed in the "dual" socket of the IPS7 card, and secondarily, the IPS6 daughter card.
The new evaluation opamps, in order of preference were:
#1 YELLOW - T5, D4, B5; Yes, this opamp edged out my long time OPA1612A favorite. It's the equal of the IPS6 card (T4, D5, B5) with a slightly different emphasis. Very smooth and clear, with pretty good imaging. Excellent bass instrument and percussive definition. Superior for both male and female vocals. Definite smile factor. I'm tempted give it all 5's but the thing is, it's really a toss up between YELLOW, OPA1612 and IPS6 card. They all have their strengths.
#2 SILVER - T4, D3, B4; Slightly bright but not harsh. Detailed but with a flat, 2D, sound character. Forward sounding vocals. Austere sound with a decidedly soft bass character. A bit exciting but overall, no smiles.
#3 WHITE - T4, D4, B3; Clear but with a slight harshness, mostly apparent on female vocals. Appears to lack low bass but that might just be an abundance of highs. Moderate depth to the sound stage but somehow not exciting. No smiles.
If you haven't figured it out by now, I like a slightly lush tonally balanced sound where the distortion character favors the 2nd harmonic. It must provide a sound stage that offers good instrument separation and depth. The fine details and dynamic range can't get lost in either the noise floor or the distortion. The YELLOW opamp meets that criteria, falling a bit short only in it's ability to provide a fully 3D sound stage.
Some idle speculation:
I'm just guessing here but I think YELLOW maybe is saved by a good (not excessive) slew rate, low THD and low noise. Comparing it to the OPA1612, I may be hearing the difference between the OPA1612's bipolar inputs and either JFET or FET inputs in the YELLOW device. I won't know for sure until Mark reveals the opamp device identifications.
amandarae:
I have not built the Norwood although the concept of using a high current low output impedance buffer embedded in the feedback loop of an opamp to drive the Edcor transformer seems to hold great promise. For the latest development in this arena, I refer you to the current issue of audioxpress magazine, March 2021 and the article by Michael Steffes on his design for a compensated inverting composite amplifier based on the TPA6120A2.
I have not built the Norwood although the concept of using a high current low output impedance buffer embedded in the feedback loop of an opamp to drive the Edcor transformer seems to hold great promise. For the latest development in this arena, I refer you to the current issue of audioxpress magazine, March 2021 and the article by Michael Steffes on his design for a compensated inverting composite amplifier based on the TPA6120A2.
Except that you also happen to LOVE the IPS6 ... which is a transconductance amplifier. Like all other transconductance amplifiers, IPS6's output impedance is extremely high. And its output stage is decidedly low current, in fact it's constant low current. Q7 is a CCS thanks to the constant DC voltage at its base (from IC1).
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Attachments
Thank you for the response AVDG!
I am just curious if you compared the two, hence the question. I had and I found that they are quite identical, except for me the Norwood is a bit "smoother" which makes the IPS6 a little "cleaner".
One thing that I noticed with my IPS6 is that it has a thump during power up and power down of the M2X (using HX9KPXG). I am not sure if its the card but I do not have the thump using the other 6 cards (except Cedarburg as I have not built it yet). I completed the fine tuning routine (took me about an hour) and I was measuring +-5 on L and +- 7 on R range.
I bought another pair of IPS6 cards and will assemble it and try if it will behave the same but before doing that, I will investigate the J113 and confirm matching from the built pair.
Again, thank you for the response.
I am just curious if you compared the two, hence the question. I had and I found that they are quite identical, except for me the Norwood is a bit "smoother" which makes the IPS6 a little "cleaner".
One thing that I noticed with my IPS6 is that it has a thump during power up and power down of the M2X (using HX9KPXG). I am not sure if its the card but I do not have the thump using the other 6 cards (except Cedarburg as I have not built it yet). I completed the fine tuning routine (took me about an hour) and I was measuring +-5 on L and +- 7 on R range.
I bought another pair of IPS6 cards and will assemble it and try if it will behave the same but before doing that, I will investigate the J113 and confirm matching from the built pair.
Again, thank you for the response.
Summary of Mark Johnson mystery opamps evaluation
Here is my summary comparison of the 6 mystery opamps and my two reference devices.
For the way that I arrived at the following evaluations, please refer to my previous two posts, #4603 (located here: The diyAudio First Watt M2x) and #4727 (located here: The diyAudio First Watt M2x).
On a number scale of 1 to 5 (5 best) I ranked the following characteristics:
T - Transient Response (a combination of high slew rate and low transient intermodulation distortion)
D - Depth (a combination of low noise and low total harmonic distortion)
B - Balance (a combination of wide bandwidth and flat frequency response)
I'm adding a 4th characteristic, distilled from my original comments:
SF - Smile Factor - do you break out in a grin listening to the music?
In order of preference (note: the first 3 are pretty much interchangable in my preference, they are all very good)
#1 IPS6 - T4, D5, B5, SF5
Smooth, detailed and open with very good imaging. Great sound stage. Studio monitor reference sound.
#2 OPA1612 - T4, D4, B5, SF5
Smooth and detailed with good imaging. Good sound stage. Laid back yet open sound makes extended listening a pleasure. Similar to the Burson V6 Classic.
#3 YELLOW - T5, D4, B5, SF5
Very smooth and clear, with pretty good imaging. Excellent bass instrument and percussive definition. Superior for both male and female vocals. Exciting. Reminds me of the Burson V6 Vivid.
#4 BLUE - T3, D3, B4, SF4
Balanced overall. Clean but not harsh. OK sound stage. Nothing stands out. No surprises. The Toyota Corolla of opamps.
#5 SILVER - T4, D3, B4, SF3
Slightly bright but not harsh. Detailed but with a flat, 2D, sound character. Forward sounding vocals. Has an austere sound with a decidedly soft bass character.
#6 WHITE - T4, D4, B3, SF3
Clear but with a slight harshness, mostly apparent on female vocals. Appears to lack low bass but that might just be an abundance of highs. Moderate depth to the sound stage but somehow not exciting.
#7 RED - T2, D2, B3, SF3
Very smooth and non-fatiguing but a bit dull. Slightly veiled and 2-dimensional sounding. Did not handle female vocals well. Soft overall, like late 1970's NAD amplifiers.
#8 GREEN - T2, D3, B2, SF2
Very bright, translating to some apparent detail but unbalanced. Lacks imaging and sound stage depth.
Here is my summary comparison of the 6 mystery opamps and my two reference devices.
For the way that I arrived at the following evaluations, please refer to my previous two posts, #4603 (located here: The diyAudio First Watt M2x) and #4727 (located here: The diyAudio First Watt M2x).
On a number scale of 1 to 5 (5 best) I ranked the following characteristics:
T - Transient Response (a combination of high slew rate and low transient intermodulation distortion)
D - Depth (a combination of low noise and low total harmonic distortion)
B - Balance (a combination of wide bandwidth and flat frequency response)
I'm adding a 4th characteristic, distilled from my original comments:
SF - Smile Factor - do you break out in a grin listening to the music?
In order of preference (note: the first 3 are pretty much interchangable in my preference, they are all very good)
#1 IPS6 - T4, D5, B5, SF5
Smooth, detailed and open with very good imaging. Great sound stage. Studio monitor reference sound.
#2 OPA1612 - T4, D4, B5, SF5
Smooth and detailed with good imaging. Good sound stage. Laid back yet open sound makes extended listening a pleasure. Similar to the Burson V6 Classic.
#3 YELLOW - T5, D4, B5, SF5
Very smooth and clear, with pretty good imaging. Excellent bass instrument and percussive definition. Superior for both male and female vocals. Exciting. Reminds me of the Burson V6 Vivid.
#4 BLUE - T3, D3, B4, SF4
Balanced overall. Clean but not harsh. OK sound stage. Nothing stands out. No surprises. The Toyota Corolla of opamps.
#5 SILVER - T4, D3, B4, SF3
Slightly bright but not harsh. Detailed but with a flat, 2D, sound character. Forward sounding vocals. Has an austere sound with a decidedly soft bass character.
#6 WHITE - T4, D4, B3, SF3
Clear but with a slight harshness, mostly apparent on female vocals. Appears to lack low bass but that might just be an abundance of highs. Moderate depth to the sound stage but somehow not exciting.
#7 RED - T2, D2, B3, SF3
Very smooth and non-fatiguing but a bit dull. Slightly veiled and 2-dimensional sounding. Did not handle female vocals well. Soft overall, like late 1970's NAD amplifiers.
#8 GREEN - T2, D3, B2, SF2
Very bright, translating to some apparent detail but unbalanced. Lacks imaging and sound stage depth.
The Sparkfun adapters that I used, when I sent SOIC-8 opamps-on-DIP-adapter-cards to member @avdesignguru for listening tests, were the red ones sold by Sparkfun. Part number 13655:
I assembled the SOIC-8 opamp chips onto the adapters myself, using this equipment
You could do this job yourself. (I did the job myself). Or you could arrange some kind of a barter or trade with another DIYer. You give her X and she gives you assembled opamps on DIP adapters. An exchange of value, for value.
Or I guess you could go visit your local TV repair shop and ask them whether they would do the job for money.
I assembled the SOIC-8 opamp chips onto the adapters myself, using this equipment
Everybody has their own opinion of course, but MY opinion is that super thin 0.015" diameter solder, not lead-free, is amazingly helpful for hand soldering SMD components.
You could do this job yourself. (I did the job myself). Or you could arrange some kind of a barter or trade with another DIYer. You give her X and she gives you assembled opamps on DIP adapters. An exchange of value, for value.
Or I guess you could go visit your local TV repair shop and ask them whether they would do the job for money.
Unfortunately, age and injury issues leave me in the position where I'd have to outsource any SMD stuff. I'll post your barter suggestion in the appropriate forum.
Regards,
Dan
