Thomo said:You can laugh as much as you like:
The fets and transistor were the wrong way round
Making music right now. I have a hum, but that's just poor placement of the reg. I shall attempt a shunt reg today. I'll also fit the Russian Silver Mica's and paper in oils.
Thanks for your help, yet again.
Good work Lee
I recently upgraded my present setup with a Rayreg on the 101b preamp.
This made a lot of difference because the MM phono pre is powered by the new regs.
My TT is killing the CDP already.... can not wait to try the salas riaa and shunt.
Ricardo
Here's a couple of pics of my pre/phono.
http://www.diyhi-fi.co.uk/images/system/Pre Front View.jpg
http://www.diyhi-fi.co.uk/images/system/Pre Top View.jpg
The wiring will be tidied up when the parts are finalised and the shunt reg is in.
Lee.
http://www.diyhi-fi.co.uk/images/system/Pre Front View.jpg
http://www.diyhi-fi.co.uk/images/system/Pre Top View.jpg
The wiring will be tidied up when the parts are finalised and the shunt reg is in.
Lee.
Nice space and box. If you continue to have hum problems after finishing, remember that most possibly is gonna be due to no use of shielded coax for signal. Especially on input from TT. If you face any ground loops ask me too. Also, you must decide what kind of buffer you want to employ so not to have 2. Remember, you already have Q5 doing this. You may do the B1 I have shown above, directly at your Riaa tail and compare the Q5 or your external buffer. If you gonna use an external one, just toss Q5 and R19, link Q2 drain to C4 in, and take output from current out point. So you have one redundant stage less. More transparent.
Your Meridian 101 will be fed in some 10K impedance input, if I recall correctly. So you will need a buffer functioning stage, or a stand alone buffer. Rule of thumb is to drive at least 10 times more input impedance than the value of your Riaa's second stage drain resistor. Keeps the signal level high and the distortion low.
I do not have that info but here is what I found:salas said:
"103 power amp input impedance 11k.
Optimally you can use a 101 pre with a 0.775v/0db sensitivity power amp."
Of course my setup consists on Meridian 101b pre + 103 power amp.
Hope this helps.
I am now wondering if I can use only a riaa +pot + power amp and do the same with the CDP: CD with DOS + pot + power amp.
That would be a blast.
Ricardo
The Riaa has to stay about 600mV peak to peak (0.21V RMS) so to sound clean without pressing its second stage and elevate distortion.
That is where I keep it for chosen cartridges and suitable gain structure. Many records have higher modulation parts and can be roughening it if we push the gain. Have done experiments on that for the given circuit. It lends a nice volume rotation range that way with most records, not far away from most average CD recordings.
The impedance of Meridian 103, asks for a buffer stage and a gain of 4 after the Riaa so to be driven correctly. The Riaa version that Lee makes, and your 46dB more sensitive but exactly the same topologically that I have posted for you, includes a Q5 buffer stage. So you can use your 101 for pre, and its low impedance input will not drag down the Riaa.
That is where I keep it for chosen cartridges and suitable gain structure. Many records have higher modulation parts and can be roughening it if we push the gain. Have done experiments on that for the given circuit. It lends a nice volume rotation range that way with most records, not far away from most average CD recordings.
The impedance of Meridian 103, asks for a buffer stage and a gain of 4 after the Riaa so to be driven correctly. The Riaa version that Lee makes, and your 46dB more sensitive but exactly the same topologically that I have posted for you, includes a Q5 buffer stage. So you can use your 101 for pre, and its low impedance input will not drag down the Riaa.
Yes,
Now the 4562 is so much more detailed.
The big difference came when I replaced the stock regs "MC78 / 79" by 317/337 setup.... Now the TT killed the CDP.
I am running the Benz with the 101 MM riaa, and with the new PSU + output opamp, it really sings.
Imagine what a salas riaa might do ! Than is why I have been pushing Lee
Now the 4562 is so much more detailed.
The big difference came when I replaced the stock regs "MC78 / 79" by 317/337 setup.... Now the TT killed the CDP.
I am running the Benz with the 101 MM riaa, and with the new PSU + output opamp, it really sings.
Imagine what a salas riaa might do ! Than is why I have been pushing Lee
Attachments
It sounds awesome right now, but I believe there is room for improvement.
The opamp is followed by a electronic switch (used for delay on power up) and I would like to clean the sound up.
When I replaced the 4562 in my CDP by a jfet DOS, I was totally amazed.
I need something like that for the TT.
Ricardo
The opamp is followed by a electronic switch (used for delay on power up) and I would like to clean the sound up.
When I replaced the 4562 in my CDP by a jfet DOS, I was totally amazed.
I need something like that for the TT.
Ricardo
salas said:
It is indeed! I used a higher power transistor as it's what I had to hand. I tried it with all 2sk170's, which had better bass but sounded a bit too "gloopy".
Originally I was using just the pot between cdp and power amp, adding the buffer stage was a huge step forward. Massively increased sound-quality in every single area. I have bypassed the buffer on the phono just using the Pedja Rogic buffer.
The phono stage is sounding really good even with just an lm317 reg. Still have that large hum, but that's probably to do with poor cable routing inside and outside the pre.
Cheers, Lee.