Would it help to lower the ripple from the input?
E.g. if you used a 7918 so a regulated 18 VDC was used as input to the 7915 would that lower the noise?
Also interesting if there is a special brand that has lower noise than other.
Now only a small part of the 125 uV noise will be present at the output of the P3.
E.g. if you used a 7918 so a regulated 18 VDC was used as input to the 7915 would that lower the noise?
Also interesting if there is a special brand that has lower noise than other.
Now only a small part of the 125 uV noise will be present at the output of the P3.
Speaking of rolling amps...
Is there a table that describes the optional set of opamps and their published noise levels?
I recall there was a list of opamps in the schematic...
Is there a table that describes the optional set of opamps and their published noise levels?
I recall there was a list of opamps in the schematic...
I used google to search for the data sheets for the opamps listed in the schematic and also the opamps I have myself.
So far the one with lowest noise that also is unity gain stable and also can run with -+15VDC is the ADA4898 (around 1nV/.....).
I have settled for that one and I have ordered some of the dual versions.
Often it seems that a dual version has a bit less performance than same opamp as single.......but not this one.
Where did you order it? You got four dual, huh? Plus some spares...
I plan on testing the Burson v6 Classics and perhaps the Vivids. I don't have enough v5 duals...
Jim hinted at the Sparkos..
https://sparkoslabs.com/product/dual-discrete-op-amp-ss3602/
Them discrete opamps get pricey pretty fast...
I ordered them at DigiKey. I was a fool with the first order where I only ordered 4 (no free shipping and VAT added (below 150 Euro order they add VAT)).
Later I ordered 12 + some 2SK209......free shiping, no VAT added and tax paid by DigiKey if UPS was used as carrier.
From Newark.com I got this message some hours after the order:
"Thank you for your recent order. Unfortunately, part number 50AK4574 has a DNS(Do not sell) restrictions and cannot be sold to you at this time. Because this is the only item on the order, it has been cancelled. We apologize for the inconvenience."
Strange?
RS Components did not have the 4898 but I think Mouser have them also.
Later I ordered 12 + some 2SK209......free shiping, no VAT added and tax paid by DigiKey if UPS was used as carrier.
From Newark.com I got this message some hours after the order:
"Thank you for your recent order. Unfortunately, part number 50AK4574 has a DNS(Do not sell) restrictions and cannot be sold to you at this time. Because this is the only item on the order, it has been cancelled. We apologize for the inconvenience."
Strange?
RS Components did not have the 4898 but I think Mouser have them also.
Power supply is done. I’m using twisted 18ga wire for positive, negative, and audio ground. I ran a green/yellow earth ground in the bundle, too. We’ll see if I terminate the earth ground on the other end. I may swap this out for some shielded cable later.
Umbilical is wrapped in techflex. I have some heat shrink on the tech flex at the PSU box cable gland. You can see ferrules for wire terminations into the PCB screw block connectors. The umbilical is appx. 1.3m long.
Connector is a 4 pin neutrik xlr. It’s 4 pins to eliminate the possibility of connecting power to an audio signal jack.
Umbilical is wrapped in techflex. I have some heat shrink on the tech flex at the PSU box cable gland. You can see ferrules for wire terminations into the PCB screw block connectors. The umbilical is appx. 1.3m long.
Connector is a 4 pin neutrik xlr. It’s 4 pins to eliminate the possibility of connecting power to an audio signal jack.
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Regarding the use of Burson opamps:
They only recommend the V6 for MM cartridge. I assume it is because of the noise figure?
As far as I can see they don't specify noise in their datasheet?
https://drive.google.com/file/d/1JyV88oA-33QHSHbGYF16A3FRW1mDRV1N/view
Final pix for the day. I need to wire up the phono chassis, then test, then listen.
These boxes are prototypes that will be available in the near future from Gianluca at Modushop / Hifi2000. More news on that will come soon.
Good eye, MEPER. I’m using LME49720. No better reason than I have a bunch of them in my parts stash.
These boxes are prototypes that will be available in the near future from Gianluca at Modushop / Hifi2000. More news on that will come soon.
Good eye, MEPER. I’m using LME49720. No better reason than I have a bunch of them in my parts stash.
Attachments
Soooo looking forward to getting mine. Then I can see the front panels instead of just the cad drawings… which looked wonderful.
😎
😎
The Vendetta Research SCP-2 moving coil preamp (1988) was a two chassis solution.
The Pass Labs XP-22 , XP-25 , XP-27 , and Xs moving coil preamps are all two chassis solutions.
The Pass Labs X0.2 , XP-30 , and XP-32 moving coil preamps are all three chassis solutions.
You might enjoy doing a little research to see if there are published measurements for any/all of these.
The Pass Labs XP-22 , XP-25 , XP-27 , and Xs moving coil preamps are all two chassis solutions.
The Pass Labs X0.2 , XP-30 , and XP-32 moving coil preamps are all three chassis solutions.
You might enjoy doing a little research to see if there are published measurements for any/all of these.
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The question isn’t will the two-chassis be better, it of course will, but instead will the one-chassis be quiet enough.
That’s what I’m testing.
In case anyone is interested or paying attention, the difference between ZTX450 and ZTX851 in the cap multiplier is negligible. Remember that your ears are most sensitive to noise in the region around 6kHz. In the days to come, I will review more readily available transistors.
The measurement amplifier I am using is one of Gerhard's designs and has a lower threshold in the vicinity of 300pV/RtHz above 500Hz. (Oh, I am also powering it with Jan's "Silent Switcher").
Does it matter? Will see on the quiet passages of some LP's.
The measurement amplifier I am using is one of Gerhard's designs and has a lower threshold in the vicinity of 300pV/RtHz above 500Hz. (Oh, I am also powering it with Jan's "Silent Switcher").
Does it matter? Will see on the quiet passages of some LP's.