Tell us what output in mV is your cartridge spec, if you used both Q1 & Q2, if the type is K170BL or GR (for correct calculations we need IDSS), if you used R2 or R3 or both and in what value. Measure mV drop across those resistors. This can hint to IDSS if we also know your R13 value and the voltage drop across it too. There can be mute if you use only Q1 and populate R3 instead of R2 for instance. Or the opposite. Wrong Q3 type or placement can shut it down also. If you use K170 of wrong IDSS for unsuitable resistors around it you can shut down the input bias also. You got to hunt with VR2x for proper TP1-TP2 as in the manual. In any case even when properly recalculated to DC bias, the gain will be lower than with same IDSS K369. In other words you modified the whole input stage randomly by just throwing in any K170. Give us the asked above data to give you some viable solution.
about 14 months after building work!
Idss wrong......big bang problems
.
Thanks again to Nick Salas and his patience!
as it is now.
where it will be boxed.
the team.
Idss wrong......big bang problems
.Thanks again to Nick Salas and his patience!
as it is now.
An externally hosted image should be here but it was not working when we last tested it.
where it will be boxed.
An externally hosted image should be here but it was not working when we last tested it.
the team.
An externally hosted image should be here but it was not working when we last tested it.
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You used a local relay before R14 to choose alternative input gain stages as I suggested?
Thanks RC. It will take me some time to understand this. Is this an extra pcb so you only reused the shunt regulator? What would be needed to just switch between input stages if even possible to reuse anything earlier than C3 and preferably even earlier? Please, I do not want to be disrespectful - I'm sure it is as you wish it to be but I'm wondering if I could reuse more of the intermediate/output stages.
I'll have a look at the schematic as well to see if more can be reused. Then again it is possible that other brands/types of C3/C4 and other components are prefered at 43dB.
Regards
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I just duplicated the input stage leaving the riaa filter and output stage common to both gains.
There is a chip fed relay just before the riaa filter and the first stage cascode bias circuit is also common to both gains.
What you see here is only the amp.
The shunts are built in external boards. (In this example I am using two shunts per channel so there is one shunt for the input stage and another for the output stage in each channel
Using two shunts provides more overall lucidity and perceived attack.
Dear SALAS and teabag,
Have been playing with computers for audio the last couple of months and went back to the phonograph over the weekend.
At the same time i improved my standalone motor setup with the LENCO. Had kludged it originally and finally took the time to do it better Sunday. I find this makes as much difference with the LENCO as it does with belt driven tables.
The improvement was immediately obvious. I had not isolated the motor well enough from the base which it and the turntable sit upon. I placed a piece of high quality plywood atop my original gigantic mdf/baltic birch layered plinth which acts as the base for the slate plinth (below this is a large sandbox and some pieces of cedar post to bring the table to a good height) and between this old plinth and the board a generous amount of good latex caulk (1/4 inch).
Before the motor would excite the unattached board and made me think I had a noisy motor - instead it was acting as a soundboard. Now all is quiet.
Maybe I got it adjusted really well because the sound has IMMEDIACY - a major improvement if BARANEK's law is not at work here.
Hearing all of this improved sound make me wonder: even though I am getting excellent sound from my prized phono pre-amp could I be missing something running it directly into my amplifiers? I use only a pair of CADDOCK resistors to reduce gain but it is driving two amps, one, a First Watt SIT (10k input but with a cap on the input to HP at 500 hz) the other a standard 100K input and an electronic crossover for the bass with a 40K input. This must be a fairly easy load (one would not think so) since my SOEKRIS DAC will also drive this without sounding strained.
Nonetheless, my chronic audio nervosa makes me constantly question whether it would sound better with a subsequent line stage.
I know in many ways this is a silly question. I do not own a line stage nor know anyone who has one I could borrow so the only way to find out is to get one and I do not want to do this if the likelihood of improvement is negligible.
SALAS, your experience being immensely greater than mine, what do you think the chances are of improvement removing that load from the phono amp?
I am still immensely pleased with my last phono amp. I cannot imagine anything beating it hands down. The only other way to improve the sound of this thing would be to get a better cartridge which would be a better use of money than another phono amp. Thanks very much to both you and teabag for this fine amplifier. (can't say it enough)
Take care,
Have been playing with computers for audio the last couple of months and went back to the phonograph over the weekend.
At the same time i improved my standalone motor setup with the LENCO. Had kludged it originally and finally took the time to do it better Sunday. I find this makes as much difference with the LENCO as it does with belt driven tables.
The improvement was immediately obvious. I had not isolated the motor well enough from the base which it and the turntable sit upon. I placed a piece of high quality plywood atop my original gigantic mdf/baltic birch layered plinth which acts as the base for the slate plinth (below this is a large sandbox and some pieces of cedar post to bring the table to a good height) and between this old plinth and the board a generous amount of good latex caulk (1/4 inch).
Before the motor would excite the unattached board and made me think I had a noisy motor - instead it was acting as a soundboard. Now all is quiet.
Maybe I got it adjusted really well because the sound has IMMEDIACY - a major improvement if BARANEK's law is not at work here.
Hearing all of this improved sound make me wonder: even though I am getting excellent sound from my prized phono pre-amp could I be missing something running it directly into my amplifiers? I use only a pair of CADDOCK resistors to reduce gain but it is driving two amps, one, a First Watt SIT (10k input but with a cap on the input to HP at 500 hz) the other a standard 100K input and an electronic crossover for the bass with a 40K input. This must be a fairly easy load (one would not think so) since my SOEKRIS DAC will also drive this without sounding strained.
Nonetheless, my chronic audio nervosa makes me constantly question whether it would sound better with a subsequent line stage.
I know in many ways this is a silly question. I do not own a line stage nor know anyone who has one I could borrow so the only way to find out is to get one and I do not want to do this if the likelihood of improvement is negligible.
SALAS, your experience being immensely greater than mine, what do you think the chances are of improvement removing that load from the phono amp?
I am still immensely pleased with my last phono amp. I cannot imagine anything beating it hands down. The only other way to improve the sound of this thing would be to get a better cartridge which would be a better use of money than another phono amp. Thanks very much to both you and teabag for this fine amplifier. (can't say it enough)
Take care,
Rick, you are welcome. Thanks for your kind words.
Well, your (and ours) FSP has a JFET output buffer stage with circa 50 Ohm impedance. That stage is good for about 16mA pk-pk drive, 18mA the most. If there is enough gain (max audio volume is satisfactory) in your system, and the bass is firm as it is configured (buffer's current drive is enough for your interconnects & amps), I would be reluctant to suggest you add some further active link in the chain. It could make the macrodynamics more noticeable but in the purity department I don't see a way of how "more" will be cleaner than "less" no matter how "perfect" the extra circuitry. I would make a test first if in your shoes. I'd put together a quick one with some good opamp just to gauge if I lack in the dynamic drive department in my current config vs some detail gets masked or the tonality gets contrived. And then set sail for some inspiring new DIY or not.
Well, your (and ours) FSP has a JFET output buffer stage with circa 50 Ohm impedance. That stage is good for about 16mA pk-pk drive, 18mA the most. If there is enough gain (max audio volume is satisfactory) in your system, and the bass is firm as it is configured (buffer's current drive is enough for your interconnects & amps), I would be reluctant to suggest you add some further active link in the chain. It could make the macrodynamics more noticeable but in the purity department I don't see a way of how "more" will be cleaner than "less" no matter how "perfect" the extra circuitry. I would make a test first if in your shoes. I'd put together a quick one with some good opamp just to gauge if I lack in the dynamic drive department in my current config vs some detail gets masked or the tonality gets contrived. And then set sail for some inspiring new DIY or not.
My thanks to you SALAS, yet again, for your contributions to audio.
That is what is gnawing at me is that the bass is thunderous when it is supposed to be and the dynamics are better than I have ever experienced.
Yet, we always want something more from our components even if it would then require them to make up something different from what is given.
I know I have asked this question a few times before in different ways but I can assure you I am (finally!) satisfied that my SALAS phono is not held back by the load it must drive.
I certainly do not want to add another gain stage since I do not need the gain and who needs more electronics in the path? Nothing could be better than a phono amp that can take the output of the cartridge and send it along to the power amps!
Plenty of gain, even after 3 dB reduction it can be a little loud on some recordings. So there is more than I am needing. I do wish I could find something to use for a volume control but would rather have no control over volume than to use a control that spoils the sound.
Which brings me to another question: have you heard a volume control that works well with the phono stage, assuming you do not use a line amp!? And even if you do I would like to hear your opinion.
Take care,
That is what is gnawing at me is that the bass is thunderous when it is supposed to be and the dynamics are better than I have ever experienced.
Yet, we always want something more from our components even if it would then require them to make up something different from what is given.
I know I have asked this question a few times before in different ways but I can assure you I am (finally!) satisfied that my SALAS phono is not held back by the load it must drive.
I certainly do not want to add another gain stage since I do not need the gain and who needs more electronics in the path? Nothing could be better than a phono amp that can take the output of the cartridge and send it along to the power amps!
Plenty of gain, even after 3 dB reduction it can be a little loud on some recordings. So there is more than I am needing. I do wish I could find something to use for a volume control but would rather have no control over volume than to use a control that spoils the sound.
Which brings me to another question: have you heard a volume control that works well with the phono stage, assuming you do not use a line amp!? And even if you do I would like to hear your opinion.
Take care,
These pots are good enough
High Quality Audio & Industrial Attenuators
But as you lower the volume, the impedance rises and you may eventually discover that you need a buffer after the pot for constant drive quality across the volume range. Maybe a buffer op-amp or a DCB1. Just simulate some steps with different resistors values in your now divider so to form an idea. Before you splash out only to get mildly disappointed.
High Quality Audio & Industrial Attenuators
But as you lower the volume, the impedance rises and you may eventually discover that you need a buffer after the pot for constant drive quality across the volume range. Maybe a buffer op-amp or a DCB1. Just simulate some steps with different resistors values in your now divider so to form an idea. Before you splash out only to get mildly disappointed.
Wow, those are beautiful.
Had never seen these before.
I would not care too much about the sound being affected at low volume - just want something to fine tune at my general listening level.
The Polish are doing many great things for our hobby! Slavs in general these days - as if they have taken the mantle from the Japanese?
Had never seen these before.
I would not care too much about the sound being affected at low volume - just want something to fine tune at my general listening level.
The Polish are doing many great things for our hobby! Slavs in general these days - as if they have taken the mantle from the Japanese?
I haven't finished my Simplistic Phono stage with Salas shunts yet, but my preamp set-up may be of interest to you. It consists of a combination of an input selector that utilised relays for the signal path, then the signal goes through a DCB1, with Salas shunts, as suggested above. For the volume control, I utilised a remote control unit pot, controlling an optical resistor volume control, fed by a 5v Salas shunt. The signal doesn't go through the pot at all - the pot is simply a voltage regulator for the leds seen by the optical variable resistors that the signal does go through. So, the signal is kept very pure, simple and direct, by the usage of a lot of external stuff and quality power supplies. Also, it's not really a pre-amp as there is zero gain. It should really be called a remote control selector, buffer, volume control unit I guess. It sounds entirely transparent.
I am intrigued by those but the complication and variability of the "optos" made me nervous. I went as far as to get the parts but could not get myself to finish it. (I can hear teabag chuckling ...)
The units recommended by SALAS are expensive but look worth the money and it is impossible to beat the reliability of a good switch and quality resistors.
A quandary for sure!
THANKS for your recommendation.
The units recommended by SALAS are expensive but look worth the money and it is impossible to beat the reliability of a good switch and quality resistors.
A quandary for sure!
THANKS for your recommendation.