Hi there
I have researched this topic with no obvious conclusion.
let's say I find the brightness of some records a bit much. Is there a way to introduce some form of adjustability into an RIAA passive network that sits between 1st stage (C3G in my case) outputting to a D3A (this is my phono stage. The signal is then fed to a pair of 6G6g in SRPP as preamp)
The network I have in place is derived from the KABUSA riaa calculator
Any help will be appreciated
Nick
I have researched this topic with no obvious conclusion.
let's say I find the brightness of some records a bit much. Is there a way to introduce some form of adjustability into an RIAA passive network that sits between 1st stage (C3G in my case) outputting to a D3A (this is my phono stage. The signal is then fed to a pair of 6G6g in SRPP as preamp)
The network I have in place is derived from the KABUSA riaa calculator
Any help will be appreciated
Nick
Because of interactions, changing the 75uS time constant (primarily via C2) will also affect the overall response.
But you could still do it. Or else add a series RC network in shunt at the phono output instead.
But you could still do it. Or else add a series RC network in shunt at the phono output instead.
I have placed in the values i use from this handy calculator. I am aware of the sun valley phono section but would like to investigate options for my phono stage first.
Thanks to rayma for your input
Thanks to rayma for your input
Hi Russc
I have an At440Ml and have it loaded to 32k- capacitance I am working on- The leads from the tonearm comprise that capacitance.
I had built a phono stage comprising a c3g feeding a 6sl7(in srpp) feeding into 6g6g for output to power amps. it sounded good. I bought a bunch of D3a's 15 years ago (who wasn't into stockpiling right?) and it dawned on me that at 64 yrs of age, my stockpiling days are done and that I should start using what I have got. I can't believe how much D3A's go for now.
Long story short, whilst the d3a's (which are now in the position of the 6sl7's) have amazing clarity and dynamics, I cannot tame the brightness or harshness they have brought to the party.
I would say this happens at around 3 to about 5kHz. For example, most of Sultans of swing sounds great but when Knopfler is doing the guitar work, the higher notes really grate. Voice is excellent.
I will draw a schematic and post it. I have not the talent to identify what may be causing the treble harshness. I have tried many different operating points of the d3a for little difference. The c3g feeds into the d3a with the passive RIAA network (as per the KABUsa calculator posted above)
if I can tame the harshness, I will be happy. If not, I i will go back to the 6SL7's.
I have an At440Ml and have it loaded to 32k- capacitance I am working on- The leads from the tonearm comprise that capacitance.
I had built a phono stage comprising a c3g feeding a 6sl7(in srpp) feeding into 6g6g for output to power amps. it sounded good. I bought a bunch of D3a's 15 years ago (who wasn't into stockpiling right?) and it dawned on me that at 64 yrs of age, my stockpiling days are done and that I should start using what I have got. I can't believe how much D3A's go for now.
Long story short, whilst the d3a's (which are now in the position of the 6sl7's) have amazing clarity and dynamics, I cannot tame the brightness or harshness they have brought to the party.
I would say this happens at around 3 to about 5kHz. For example, most of Sultans of swing sounds great but when Knopfler is doing the guitar work, the higher notes really grate. Voice is excellent.
I will draw a schematic and post it. I have not the talent to identify what may be causing the treble harshness. I have tried many different operating points of the d3a for little difference. The c3g feeds into the d3a with the passive RIAA network (as per the KABUsa calculator posted above)
if I can tame the harshness, I will be happy. If not, I i will go back to the 6SL7's.
Assuming you are using the C3a in triode mode, to R1 in the KAB calculator you have to add the anode resistance of the first stage. Note also that rp will change with anode current.
Leave what you've got intact.
Have a look at the Mcintosh c8 schematic.
They have all the adjustments a person could want and more...
Edit: the original c8, not the modern one
Have a look at the Mcintosh c8 schematic.
They have all the adjustments a person could want and more...
Edit: the original c8, not the modern one
If the type number is AT-440ML, its inductance is 490mH at 1kHz, so @jackinnj simulation perhaps correct.
If you scribe the values of components and power supply voltage, I will simulate for you the phono and its behaviour.
I have an AT440ML. It should sound right with ~150pF of cable capacitance and 47K (and no additional capacitors). Check that the pre-amp's first stage is not adding much capacitance through Miller multiplication.
"Sultans of Swing" sounds rolled-off to me, which is not uncommon for recordings in that time frame.
Ed
Gary Galo had a two stage phono pre, adjustable for all the common recording playback regimes -- in LinearAudio quite a while back. https://linearaudio.net/archival-phono-preamplifier
There was a very good thread on corrections to Gary's idea. https://www.diyaudio.com/community/threads/archival-phono-preamp-by-gary-galo.324216/
There was a very good thread on corrections to Gary's idea. https://www.diyaudio.com/community/threads/archival-phono-preamp-by-gary-galo.324216/
I am about to go to work its 8am in Australia- i will open the preamp up and record the voltages et al. I can assure everyone that the at440ml is certainly not roling off audibly to the extent of the simulation. if anyone is familiar with the first track of the "wish you were here" album, it starts with some very quiet and eerie synth sounds then a delicate decrescendo of individual notes..that is very detailed in its reproduction, more so than I have heard with the 6sl7 and that is with either 47k or 32 k loading. I suspect it might be my operating points. i will repost in about 12 hours
Thank you to everybody
Thank you to everybody
For example the little higher impedance correction chain helps to smoothing out frequency resolution.
Hi Euro21
Thank you very much for your efforts. I am still scratching my head as to why this sounds harsh in the 3 to 5 kHz region. The riaa response of first graph certainly does not hint at that.
I will implement change of values and report back
Thanks again
Nick
Thank you very much for your efforts. I am still scratching my head as to why this sounds harsh in the 3 to 5 kHz region. The riaa response of first graph certainly does not hint at that.
I will implement change of values and report back
Thanks again
Nick