I was like WTF, how do you think im supposed to control the volume?!
He said I needed a "line stage" (i was always planning to build a tube preamp, but he claims a line stage is something different)
Anyway, the amp works fine enough on its own with most digital sources, but will likely need some form of line level control, particularly with phono input.
He tells me the volume pot will screw up the sound quality, but looking at all the schematics I can see, there is typically only one way to install a volume pot and all the line stages I see simply have the pots across the input end and ground with the wiper attached to the grid of the tube.
I dont know what he is on about, but most audiophiles seem to get OCD about less components in the signal path anyway, so if im not using a "line stage" shouldnt he be happy? lol
One thing I must say is I do hear a little mains hum if you put your ear to the speakers, at different volume levels, the noise can either change or almost go away, it seems to be the most quiet when the volume pot is turned up to about half way.
All the cable is shielded to the pot and the grids, so not sure where its picking it up from, but the pot wont be creating the noise.
He said I needed a "line stage" (i was always planning to build a tube preamp, but he claims a line stage is something different)
Anyway, the amp works fine enough on its own with most digital sources, but will likely need some form of line level control, particularly with phono input.
He tells me the volume pot will screw up the sound quality, but looking at all the schematics I can see, there is typically only one way to install a volume pot and all the line stages I see simply have the pots across the input end and ground with the wiper attached to the grid of the tube.
I dont know what he is on about, but most audiophiles seem to get OCD about less components in the signal path anyway, so if im not using a "line stage" shouldnt he be happy? lol
One thing I must say is I do hear a little mains hum if you put your ear to the speakers, at different volume levels, the noise can either change or almost go away, it seems to be the most quiet when the volume pot is turned up to about half way.
All the cable is shielded to the pot and the grids, so not sure where its picking it up from, but the pot wont be creating the noise.
A volume control in a preamp or a line stage is not inherently different from a volume control in a power amp. There are more ways available to build the former, and the L atter are rather unfashionable, that's about all there is to that.
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tell your friend that it’s not a volume pot, it’s to control possible input stage clipping on strong signals and suffices as a volume pot until your Kondo M7 line stage has been built!
The audiophile "friend" is suffering from serious, perhaps fatal, Cranio-rectal Inversion.
A line stage with gain is usually unneeded, when "standard" digital signal sources are employed. Why? Most power amps will be driven into clipping by the full, 2 VRMS, signal "standard" digital signal sources yield.
If multiple sources are to be selected amongst or lengthy interconnect cables employed, a separate control center (perhaps buffered) is in order. If only 1 or 2 sources are to be employed, the OP's configuration of volume control on the same chassis as the power amp favorably holds the number of mechanical connections in the signal path down.
A line stage with gain is usually unneeded, when "standard" digital signal sources are employed. Why? Most power amps will be driven into clipping by the full, 2 VRMS, signal "standard" digital signal sources yield.
If multiple sources are to be selected amongst or lengthy interconnect cables employed, a separate control center (perhaps buffered) is in order. If only 1 or 2 sources are to be employed, the OP's configuration of volume control on the same chassis as the power amp favorably holds the number of mechanical connections in the signal path down.
I was pretty sure I had done this, but youve got me questioning it now.
I know I soldered the shielding to the pot itself and pretty sure I grounded the other end at the RCA jack.
Yeah thats what I feel too.
Well this is what Im trying to do next, I thought I might end up building something with an FM tuner inside along with a bluetooth module and phono stage as well.
Good idea!
Well I wouldnt call him stupid, I just think he buys into snake oil like so many do in these circles.
Tell him it was cryo-treated on Mt. Fuji by a 90 year old man who has been making artisanal volume pots since the end of WWII.
No wonder most (all?) audiophiles are deaf.
Nonsense! Surely your pot was hand crafted by Kiwi virgins from solid BS & possum sh*t.
I should clarify, that its just going to be a cheap digital tuner powered by an Arduino, they seem to do the job, its only radio, so quality doesnt matter.
While a valve tuner would be pretty cool, I would have to have a separate unit and as you say, building such a thing is extremely complex and difficult to get the inductors and tuning coils, etc, i would be better off looking for a Fisher tuner if one turns up.
ROTFL
Yes, it is a contradiction i have long learned to accept. At the beginning of my audio journey i was in favour of a minimalist signal path. For the last 30 years the active line stage has been the heart of my system. For no technical reasons whatsoever.
All may sources are capable of driving long cables and serious loads, but the line stage remains an essential ingredient in getting the music to gel, have substance, natural tonality and full range dynamics.
Is it the added distortion? Noise? Input noise filtering? No idea.
Designing and building a transpaent line stage is not trivial. The vast majority of commercial offerings i have listened to are severely compromised even in the 10k + price range.
A line stage is not for increasing the level at the input of the power amplifier, in the first place. It is mainly for impedance matching between the source and the volume pot, or by helping drive the capacitance of a signal cable between them.
In many cases a "passive preamplifier" (AKA a single pot) is all that needed.
In many cases a "passive preamplifier" (AKA a single pot) is all that needed.
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When I was till in HS, a friend brought me a pair of Fisher "Laboratory Power Amplifiers" to repair. I could not for the life of me figure out what was wrong with them and I gave up. He took them to a pro, who fixed them. Culprit? The input level control pots...
So it is possible, depends on the control and what state it's in. There's umpty ways to do it, besides a mechanical component. Why, right on the front page at the moment there's a link to a Optocoupler based control https://www.diyaudio.com/forums/ven...ptocoupler-volume-control-37.html#post6666833
I once bought a stepped, stereo unit off ebay, from someone patient enough to solder up all those resistors. It worked fine. Perhaps the metal to metal switch contacts and resistor pairs are better for the signal than a sliding contact on a carbon stripe. The seller seemed to think so, of course.
So it is possible, depends on the control and what state it's in. There's umpty ways to do it, besides a mechanical component. Why, right on the front page at the moment there's a link to a Optocoupler based control https://www.diyaudio.com/forums/ven...ptocoupler-volume-control-37.html#post6666833
I once bought a stepped, stereo unit off ebay, from someone patient enough to solder up all those resistors. It worked fine. Perhaps the metal to metal switch contacts and resistor pairs are better for the signal than a sliding contact on a carbon stripe. The seller seemed to think so, of course.
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While a valve tuner would be pretty cool, I would have to have a separate unit and as you say, building such a thing is extremely complex and difficult to get the inductors and tuning coils, etc, i would be better off looking for a Fisher tuner if one turns up.
ROTFL
Well, if you just wanna have some DIY fun there are mono all-valve FM tuners you can build without a lot of tweaking & aligning.
‘Pulse Counting’
Haven’t tried myself yet but it looks very interesting
Pulse-counting FM RECEIVER