All the stuff is ordered, I'm hoping to get it at the end of the week. I already have the power supply, from another project (which didn't work 🙁 ). It's a +/-15V supply with zener diodes (I heard from someone it is a good regulator, better than 78xx and 79xx; we'll see). As soon as it is finished, I'll post some pictures.
Regards,
Mark
Regards,
Mark
Mads,
DC gain is indeed 1000. I glad at least someone was on the ball today.
Fran,
In principle you can use a step-up transformer with the VSPS. I have done so myself. Normally it is installed in front of R1, leaving R1 in place, but replacing the normal value of 47k with something that gives the correct cartridge loading (for the MC cart being used) when reflected back across the transformer.
There is not normally any resistor on the input side of the transformer.
The value of R1 is found by multiplying the recommended cartridge load by the square of the turns ratio (i.e. voltage gain^2).
Ex. 100 ohm recommended load, 20 dB (10x) voltage gain [1;10 turns ratio] of the transformer, R1=100x10^2=10k.
That your transformer has a switch for 30 or 100 ohms I presume means that in the box containing the transformer there is also already resistors across the output winding selected to give the stated reflected input impedance. If thats the case you dont need R1 in the VSPS, since this is duplication, but if the resistors with the transformer are 10k or less there is no harm done leaving R1 in the VSPS at 47k, since connected in parallel R1 doesn't significantly affect the total load.
So to recap: normally R1 is set to provide the correct input impedance for the cart. If this already done elsewhere, you can either leave R1 as it is or remove it ... dont "short it" with wires!
Finally, the reason the VSPS may not be ideal with an input transformer is that the input impedance of the cartridge as seen by the op-amps inputs is (turns ratio)^2 larger than the actual cartrdge internal impedance. Say you used a 40 ohm cart, 1:10 voltage/turns ratio, you are essentially using a 4k cartridge... this will induce some extra current noise which will actually increase the output noise measurably when a bipolar op-amp is used.
So to recap that part: generally speaking the HiZ version of he VSPS is preferred for this application.
And I feel duty bound to add that Phonoclone boards that are drop-in replacement boards for the VSPS boards are available, or the layout is at any rate. As an upgrade path its pretty economical, as the power supply and hardware is unchanged.
Markje,
Ok, good luck and I am looking forward to seeing the photos!
/R
DC gain is indeed 1000. I glad at least someone was on the ball today.
Fran,
In principle you can use a step-up transformer with the VSPS. I have done so myself. Normally it is installed in front of R1, leaving R1 in place, but replacing the normal value of 47k with something that gives the correct cartridge loading (for the MC cart being used) when reflected back across the transformer.
There is not normally any resistor on the input side of the transformer.
The value of R1 is found by multiplying the recommended cartridge load by the square of the turns ratio (i.e. voltage gain^2).
Ex. 100 ohm recommended load, 20 dB (10x) voltage gain [1;10 turns ratio] of the transformer, R1=100x10^2=10k.
That your transformer has a switch for 30 or 100 ohms I presume means that in the box containing the transformer there is also already resistors across the output winding selected to give the stated reflected input impedance. If thats the case you dont need R1 in the VSPS, since this is duplication, but if the resistors with the transformer are 10k or less there is no harm done leaving R1 in the VSPS at 47k, since connected in parallel R1 doesn't significantly affect the total load.
So to recap: normally R1 is set to provide the correct input impedance for the cart. If this already done elsewhere, you can either leave R1 as it is or remove it ... dont "short it" with wires!
Finally, the reason the VSPS may not be ideal with an input transformer is that the input impedance of the cartridge as seen by the op-amps inputs is (turns ratio)^2 larger than the actual cartrdge internal impedance. Say you used a 40 ohm cart, 1:10 voltage/turns ratio, you are essentially using a 4k cartridge... this will induce some extra current noise which will actually increase the output noise measurably when a bipolar op-amp is used.
So to recap that part: generally speaking the HiZ version of he VSPS is preferred for this application.
And I feel duty bound to add that Phonoclone boards that are drop-in replacement boards for the VSPS boards are available, or the layout is at any rate. As an upgrade path its pretty economical, as the power supply and hardware is unchanged.
Markje,
Ok, good luck and I am looking forward to seeing the photos!
/R
Today the mailman came with a package containing everything to build the VSPS.
After about a few hours of working it was finished. I already had the power supply, so I only had to build the amp itself. I was only able to test it at the computer with crappy speakers. Tomorrow I have a day off, so I will test it at my set, but I'm confident it will sound just fine.
Pictures are below:
This is the actual amp, resistors are 1W, since it was cheaper than 0,5W and 0,25W resistors:
This is the power supply, below the C are the zeners:
Both cases are connected:
Rear view:
Front view:
rjm: thanks for the schematic, I don't think it can get any easier... So, anyone who is looking for a simple phonoamp; try this, easy to build and it sounds good.
Regards,
Mark
After about a few hours of working it was finished. I already had the power supply, so I only had to build the amp itself. I was only able to test it at the computer with crappy speakers. Tomorrow I have a day off, so I will test it at my set, but I'm confident it will sound just fine.
Pictures are below:
This is the actual amp, resistors are 1W, since it was cheaper than 0,5W and 0,25W resistors:
An externally hosted image should be here but it was not working when we last tested it.
This is the power supply, below the C are the zeners:
An externally hosted image should be here but it was not working when we last tested it.
Both cases are connected:
An externally hosted image should be here but it was not working when we last tested it.
Rear view:
An externally hosted image should be here but it was not working when we last tested it.
Front view:
An externally hosted image should be here but it was not working when we last tested it.
rjm: thanks for the schematic, I don't think it can get any easier... So, anyone who is looking for a simple phonoamp; try this, easy to build and it sounds good.
Regards,
Mark
RJM, do you have any phonoclone boards? I just had a thought that I could stack them on top of the VSPS ones and add an extra set of inputs and outputs...
Don't even have an LOMC cart yet!!!
Fran
Don't even have an LOMC cart yet!!!
Fran
Don't stack them.. trust me that's begging for trouble.
Either build a new case for the phonoclone or replace the VSPS boards in the old case.
I don't have any boards at the moment, sorry...
ok, actually I do, my Phonoclone B.E. ... since I've been using the mini RC version this is my backup and I only use it for comparison now ... its prebuilt (duh) but I can sell you that if you like, email me about it if you are interested. You provide the power supply, of course...
Either build a new case for the phonoclone or replace the VSPS boards in the old case.
I don't have any boards at the moment, sorry...
ok, actually I do, my Phonoclone B.E. ... since I've been using the mini RC version this is my backup and I only use it for comparison now ... its prebuilt (duh) but I can sell you that if you like, email me about it if you are interested. You provide the power supply, of course...
woodturner-fran said:
Hi,
I have tested the VSPS with a step up. It was a mega-buck Conrad Johnson step-up. I did not do anything but to connect the CJ ground to the VSPS ground. It sounds very good.
I did not bother about the 47K at the input... Don't know if I should have, but it was just a test.
For a number of reasons its a good idea to leave R1 as 47 kohms, as a general rule that's pretty much what the designers of step up transformers expect to be loading the output.
Phonoclone mini
fran,
I just found the two unused Phonoclone mini (LM317) boards in my desk drawer! Contact me if interested.
fran,
I just found the two unused Phonoclone mini (LM317) boards in my desk drawer! Contact me if interested.
Hi,
I'm thinking about building this project. I have a technics sl-1000 (I think) and the cartridge is a AT331LP; 3.0 mv; 47k load - will this circuit work OK with this setup?
Thank you,
Matt
I'm thinking about building this project. I have a technics sl-1000 (I think) and the cartridge is a AT331LP; 3.0 mv; 47k load - will this circuit work OK with this setup?
Thank you,
Matt
Yes, it will Matt. I've used it with my Tchnics SL-1350 with vaious cartridges MM from Clearaudio to Shure.
hallo
vsp amp
is it possible too hard wire the amp ?
just too save me some time and money
and the black gate is no longer !
all sold out
is there a good cheap replacement ?
that is good enough ?
sombody said he paid just 15 dollar for all the components
i only searched for 2 c,s and the were 16 dollar a piece
whitout sending it too me
so thats not cheap at all !
can somebody help me
greetings maurice
vsp amp
is it possible too hard wire the amp ?
just too save me some time and money
and the black gate is no longer !
all sold out
is there a good cheap replacement ?
that is good enough ?
sombody said he paid just 15 dollar for all the components
i only searched for 2 c,s and the were 16 dollar a piece
whitout sending it too me
so thats not cheap at all !
can somebody help me
greetings maurice
check out http://skycoral.com/?p=78 the guy will sell the components + pcb for 20 dollars delivered (its not advertised anywhere but I asked him). he has a good rating on ebay: akita.skycoral
this does not include the sockets however.
That's a very nice deal.
Considering the amount of work involved in putting together a complete set of parts, I'd say it's an absolute bargain, and I encourage Akita to increase his prices so he properly compensates himself for the effort. (Right now I would guess he's selling at cost.) Most people would be happy to pay twice what he's asking, just for the convenience alone, even if the parts are all standard grade.
His price on the bare PCBs is also so low that I suspect his profit margin is basically zero. If he's paying anything like Olimex pricing for the boards, I know it is for a fact.
If anyone is planning on building the stereo VSPS, then I strongly recommend paying the $12 or whatever it is and getting a set of PCBs to work with, rather than trying to do it point-to-point. Working from PCBs is so much faster and easier.
/rjm
P.S. I also think he should advertise more. I'm attaching his photo of the completed board in the spirit of attracting some business for him.
Considering the amount of work involved in putting together a complete set of parts, I'd say it's an absolute bargain, and I encourage Akita to increase his prices so he properly compensates himself for the effort. (Right now I would guess he's selling at cost.) Most people would be happy to pay twice what he's asking, just for the convenience alone, even if the parts are all standard grade.
His price on the bare PCBs is also so low that I suspect his profit margin is basically zero. If he's paying anything like Olimex pricing for the boards, I know it is for a fact.
If anyone is planning on building the stereo VSPS, then I strongly recommend paying the $12 or whatever it is and getting a set of PCBs to work with, rather than trying to do it point-to-point. Working from PCBs is so much faster and easier.
/rjm
P.S. I also think he should advertise more. I'm attaching his photo of the completed board in the spirit of attracting some business for him.
Attachments
thanks for the reply🙂
it has been a while sinds i have asked the question
i resently bought the asr mini basis for 100 euro
and have been happy ever sinds🙂
20 dollars whith shipping is not much indeed
it ,s worth a try ,i also agree whith the one saying that he doesnt
make any profit whit do,s prices
anyway thanks for the link,
greetings maurice
it has been a while sinds i have asked the question
i resently bought the asr mini basis for 100 euro
and have been happy ever sinds🙂
20 dollars whith shipping is not much indeed
it ,s worth a try ,i also agree whith the one saying that he doesnt
make any profit whit do,s prices
anyway thanks for the link,
greetings maurice
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