KNielsen
Well-Known Member
Makes sense. I did see that the rails differed more after the RC-thing, not alarming, but the regulation was somewhat missing.
I'll try some more suitable values tomorrow, it's getting late here
Thanks
I'll try some more suitable values tomorrow, it's getting late here
Thanks
KNielsen
Well-Known Member
I haven't measured this yet. I'll do so
KNielsen
Well-Known Member
@mondialfan just to be sure:
I've connected my 220uf like shown before the regulated circuit. Will this affect regulation?
After some reading I think I might mislead my question with mentioning "rc snubber"?? It was the last bite of ripple that had my attention to suppress even further
I've connected my 220uf like shown before the regulated circuit. Will this affect regulation?
After some reading I think I might mislead my question with mentioning "rc snubber"?? It was the last bite of ripple that had my attention to suppress even further
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mondialfan
Well-Known Member
Here's how you want to construct the CRC, just replace 291r with 25r. Your AC mains ripple will drop drastically across the resistor. I'd go with a larger secondary capacitor. Probably 1,000uF or larger.
KNielsen
Well-Known Member
Still waiting for the new potentiometer, so continuing with some odd testing with the RC-network posted (somewhat snubber-like, but off values?! Way to high values!!)... I'm not gonna cut the traces to form a real CRC after inspection, not this unit. An external PSU would do better if I were to test a real CRC in this arrangement
I did however follow my ears regarding the improved midrange from the mystery RC-network that I cannot lookup online with "matching values" to collect it's purpose... Only my other preamp has got it that's why I'm in for a test, inspiration....
291ohm/220uf gives some feel and super detailed, but the impact is a bit to the high side in the frequency range making even minute notes a tad to clear, but not harsh.
If I calculate the same time-constant using a 470uf, the mids really starts to shine but the network adds more temperature to the transformer then normal (not alarming hot should be mentioned), and the 470uf "feels" a bit to slow compared to the 220uf. Dobling the resistor from ~170ohm to 348ohm with the same 470uf, this drops the temperature on the transformer, but most of the "musikal feel" also takes a derute thereby.
I do not have nighter 270uf or 330uf, but they are on order for later test witch might be sweet spot between heat and musical performance.
For the R as mentioned by Mondialfan in a CRC I tried raising the 10ohm resistors (R32/33, Acurus LS11) to a rough 40ohm just to get the sound experience a bit over the top. My rails are above ±18VDC so I can afford losing up til ±1volt roughly.
-At low volume with 40ohm, wow! But at higher volume things started sounding compressed, the 1000uf (C2/C3) in the PSU couldn't keep up! Back to the bench now doing 20ohm instead and the 1000uf can keep up and things sound sweet! More uf might be preferred if I'll stick with the 20ohm's. Chemi-Con KZN caps would my choice here, both 1200uf/35V and 1500uf/35V will fit the original PCB.
The 4x 0.1uf I added to the diodebridge has been removed. I couldn't hear them installed, and looking at the oscope after the regulated circuit showing a dead straight line, their purpose just added to fill. So out they go
I know there isn't any scientific writing in my post, quite opposite. Purley based on my hearing and a few measurements with my DMM and scope.
Sadly I cannot measure the impact of the RC-network that I'm working on. Most of the job is done on the back of the PCB, and I do no dare to hook it up to live 230VAC with the PCB on its back and probe around! I only measure the preamp live when it's fully installed in the chassis.
Regards
I did however follow my ears regarding the improved midrange from the mystery RC-network that I cannot lookup online with "matching values" to collect it's purpose... Only my other preamp has got it that's why I'm in for a test, inspiration....
291ohm/220uf gives some feel and super detailed, but the impact is a bit to the high side in the frequency range making even minute notes a tad to clear, but not harsh.
If I calculate the same time-constant using a 470uf, the mids really starts to shine but the network adds more temperature to the transformer then normal (not alarming hot should be mentioned), and the 470uf "feels" a bit to slow compared to the 220uf. Dobling the resistor from ~170ohm to 348ohm with the same 470uf, this drops the temperature on the transformer, but most of the "musikal feel" also takes a derute thereby.
I do not have nighter 270uf or 330uf, but they are on order for later test witch might be sweet spot between heat and musical performance.
For the R as mentioned by Mondialfan in a CRC I tried raising the 10ohm resistors (R32/33, Acurus LS11) to a rough 40ohm just to get the sound experience a bit over the top. My rails are above ±18VDC so I can afford losing up til ±1volt roughly.
-At low volume with 40ohm, wow! But at higher volume things started sounding compressed, the 1000uf (C2/C3) in the PSU couldn't keep up! Back to the bench now doing 20ohm instead and the 1000uf can keep up and things sound sweet! More uf might be preferred if I'll stick with the 20ohm's. Chemi-Con KZN caps would my choice here, both 1200uf/35V and 1500uf/35V will fit the original PCB.
The 4x 0.1uf I added to the diodebridge has been removed. I couldn't hear them installed, and looking at the oscope after the regulated circuit showing a dead straight line, their purpose just added to fill. So out they go
I know there isn't any scientific writing in my post, quite opposite. Purley based on my hearing and a few measurements with my DMM and scope.
Sadly I cannot measure the impact of the RC-network that I'm working on. Most of the job is done on the back of the PCB, and I do no dare to hook it up to live 230VAC with the PCB on its back and probe around! I only measure the preamp live when it's fully installed in the chassis.
Regards
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mondialfan
Well-Known Member
I did however follow my ears regarding the improved midrange from the mystery RC-network that I cannot lookup online with "matching values" to collect it's purpose... Only my other preamp has got it that's why I'm in for a test, inspiration....
Not really a mystery, do a search for Zobel network. There's one hanging on the output of your Acurus or Aragon amplifier, there's also one on the feedback side of the complimentary input on your Acurus amplifier. Increasing the capacitance lowers the frequency cutoff. The resistance dissipates energy through the network and lowering the resistance will lower the impedance at a given frequency.
KNielsen
Well-Known Member
Are there any TO220 MOSFET's in production today that would suit a preamp? (Or a popular TO220-type)
I've searched the types in Aragon but very few hits.
KNielsen
Well-Known Member
Found another calculator then Digikey's time-constant calculator witch I have always used. I never really understood how to use the info of the TC-value, but the other calculator I've found shows the actual cuttoff frequency instead of TC. Now it makes sense Thanks for the push @mondialfan.
Thanks for the push @mondialfan.
KNielsen
Well-Known Member
The TKD 2CP-601 pot has arrived!
I had an old NOBEL pot in my office to get a feel between the two before installing the TKD.
On the pictures the left is the TKD and the right is NOBEL.
NOBEL comes out at 50grams where the TKD is half size housing on all dimensions, with a wight of only 15grams. Initially though the turn-quality on the TKD feels substantially better then the newly oiled NOBEL. A very nice feel to the touch that all though smaller packed size do represent HIGH Quality.. Definitely way above ALPS..
The shaft is the same dimensions as NOBEL, but the pinout on the TKD is closer together so some work must be performed for install in Acurus.
I'll post a picture of the pot installed later and if there's any issues and so forth.
Regards
I had an old NOBEL pot in my office to get a feel between the two before installing the TKD.
On the pictures the left is the TKD and the right is NOBEL.
NOBEL comes out at 50grams where the TKD is half size housing on all dimensions, with a wight of only 15grams. Initially though the turn-quality on the TKD feels substantially better then the newly oiled NOBEL. A very nice feel to the touch that all though smaller packed size do represent HIGH Quality.. Definitely way above ALPS..
The shaft is the same dimensions as NOBEL, but the pinout on the TKD is closer together so some work must be performed for install in Acurus.
I'll post a picture of the pot installed later and if there's any issues and so forth.
Regards
Attachments
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KNielsen
Well-Known Member
There are some differences between the them all.. and if I should install this again some other day I would shim it like I did the pot here a few pages back, this way the shaft isn't a bit longer.....
That said the install went good!
I did a small hole in the chassis for the pot to fit perfect and the housing descent attached without the doubt that it will turn around when the nut is tightened on the front side og the chassis. Hardwired the thing to the PCB, but I think that the rotated "version" with wires to PCB was easier to work with as earlier described and shown.
Best regards
That said the install went good!
I did a small hole in the chassis for the pot to fit perfect and the housing descent attached without the doubt that it will turn around when the nut is tightened on the front side og the chassis. Hardwired the thing to the PCB, but I think that the rotated "version" with wires to PCB was easier to work with as earlier described and shown.
Best regards
KNielsen
Well-Known Member
After a few days with the new pot I have to say IT'S WORTH THE COST. It feels fantastic to the touch over the ALPS it replaced and by far the closest or better then NOBEL. Some would say they hear a difference between pots, I'm not gonna try. The preamp is quite sensitive with the new pot due to the 20kohm but not all far out, and I think maby a bit of the top hizz has gone??? That's about it....
Maby I'll measure the tracking between the two channels just for some data collect, but soundwise it seams spot on.
Still need to put on the remaining knobs, but in the meantime while waiting for the TKD-pot I found a valid dealer of Elna capacitors with a great variety in stock from Germany, so I'm waiting for a full set of Silmic ll for the pre witch I've always found amazing in terms of performance in the midrange (woodoo??), and I'll remove my RC-network at the same time when the Silmics's are installed and just do 2x8200uf with a pair 330uf Elna's attached and call this one done! On with the lid 
Good Sunday
Maby I'll measure the tracking between the two channels just for some data collect, but soundwise it seams spot on.
Still need to put on the remaining knobs, but in the meantime while waiting for the TKD-pot I found a valid dealer of Elna capacitors with a great variety in stock from Germany, so I'm waiting for a full set of Silmic ll for the pre witch I've always found amazing in terms of performance in the midrange (woodoo??
), and I'll remove my RC-network at the same time when the Silmics's are installed and just do 2x8200uf with a pair 330uf Elna's attached and call this one done! On with the lid Good Sunday
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mondialfan
Well-Known Member
Overall gain of the L10 should be unaffected by changing the volume pot from 25k to a 20k ohm. Maybe there's something strange going on with your volume pot? What is the output voltage from the source component that your feeding the L10 with? Is it > 2V?
KNielsen
Well-Known Member
I actually don't know but I'll check later.
The other preamp I did with ALPH's were also sensitive in my system.
Maby your on to something
thanks
Pio1980
AK Member
The problem is with the line input device level, not the L10.
KNielsen
Well-Known Member
I'm not sure. With the original pot 10 o'clock was loud. Now I think even 9 o'clock is quite high in volume.
My office is full of projects right now, so I haven't got space for testing the unit before I've cleaned the bench, but I think I need to do some plots just to see what's going on.
I have a stock Acurus P10 RIAA connected also, so I desided to try some vinyl for a change just to verify.
It was touchy too and low level music seams hard to dail in with only a few degrees on the knob to work with
It's not distorting or anything, just a bit aggressive gain
Regards
My office is full of projects right now, so I haven't got space for testing the unit before I've cleaned the bench, but I think I need to do some plots just to see what's going on.
I have a stock Acurus P10 RIAA connected also, so I desided to try some vinyl for a change just to verify.
It was touchy too and low level music seams hard to dail in with only a few degrees on the knob to work with
It's not distorting or anything, just a bit aggressive gain
Regards