Are we getting tangled up in nomenclature as so often happens? The above describes the input cables to the emerald (the L/R cables from the tonearm) and the L/R output cables (from the emerald to my pre amp). So starting with everything plugged into the emerald if I remove the power cable OR the L/R output cables (from emerald to my pre amp) the pop disappears. Or starting with nothing plugged into the emerald and no pop, if I add the power cable AND the L/R output cables from emerald to pre amp the pop is present.
Ok, all clear. So the Emerald powered on is enough to amplify and transmit the turn-on thump even with no connection back to the turntable.
That's interesting. The turntable motor interference is either airborne coupling or through the ground connection. You can check my moving the Emerald chassis to different locations, but I suspect instead the power ground/earth. Not sure of the reason though, as I said it's not something I've encountered before.
In the unlikely event it's airborne, those black-painted chassis are notorious for electrically isolating the panels because of poor connection through the paint. I mention that only because it's the one thing I can see as a potential issue in your build, everything else seems fine. Double heck on the power supply, the COM wire doesn't connect to the power supply chassis right? Else I'm kinda out of ideas, short of moving the TT to a different power outlet.
Hi Richard
Not that long ago I switched some equipment around between systems and ended up with what I think is a gain mismatch.
I am using a VSPS 300m kit that I purchased with the boards populated from another member in the swap meet. I finished assembly myself.
I’m pretty sure it was populated with the standard parts from your kit and is set to 40dB of gain. I am going to be confirming that R2 is set to 680 Ohms.
I am using a Denon DL103. My understanding is that it has .3 mV output.
All the information I’ve found regarding gain on this cartridge says I should be aiming for 60 dB.
I’m assuming that is just the gain of any phono amplification used prior to any preamp gain.
My first stage of amplification after the 103 is a ZYX CPP-1 head amp I found used.
I was under the impression that this ZYX head amp had 20 dB of gain, but it appears I was misinterpreting the information I found for it and it actually has 26 dB of gain.
I believe the combination of the 103, ZYX and VSPS was working pretty well previously when I was using it with a Salas DCB1 based preamp I had built.
The DCB1 was modified on the outputs with some Jensen transformers that gave it only about 6 dB of gain.
The preamp I’m currently trying to use is an old Audible Illusions 2D. According to the manual it has 30 dB of gain in the line section.
I am not using the preamp’s phono section. I plug the VSPS in to the AUX line.
Regardless of this preamp’s line stage gain, I am not getting a good quality signal from my phono source.
Essentially, I can turn the preamp volume pot up to about 50% before I get loud feedback through the system.
Even prior to that point I am getting excessive hiss and flutter noise…probably as soon as 33% of volume. Setting this level barely approaches what I would consider a hearty room filling listening session.
I’m thinking that the excess gain that is being created before the signal reaches the preamp line stage is the problem?…at 66 dB?
For reference, I am currently using a pair of Quicksilver Horn Mono amps that are driving a pair of Tannoy System 15 DMTii speakers.
The speakers have a sensitivity of about 101 dB and are similar to other horn speakers and drivers that I have used.
The amps are designed to be used with this type of high sensitivity speaker and are rated at 25 watts which is similar to most other amps I’ve built and used.
The preamp is not the best nor does it have an amazingly low noise floor, but I have no problem getting excellent performance and incredible sound levels with a full 2V signal from a digital source like my MacBook.
So my question is about setting the gain of the VSPS in this system or the possibility of making it adjustable.
I’m assuming I need to set the VSPS gain for about 34 dB if I’m understanding things correctly?
You gave a few examples in the BOM for setting gain of the VSPS. I believe R2 @ 220 Ohms results in 50 dB of gain and R2 @ 2.2 k results in 30 dB of gain.
Is there a more accurate way of trying to set the VSPS gain for the 34 dB that I need? Other than guessing the resistor value is mid way between 680 and 2.2k at about 1.5k?
Perhaps measuring voltage in and out of the circuit somehow?
Is it possible to mount a pot at R2 to make it adjustable?…or would that have a negative affect on the sound quality of the circuit?
Am I barking up the wrong tree here and the problem is elsewhere?
Not that long ago I switched some equipment around between systems and ended up with what I think is a gain mismatch.
I am using a VSPS 300m kit that I purchased with the boards populated from another member in the swap meet. I finished assembly myself.
I’m pretty sure it was populated with the standard parts from your kit and is set to 40dB of gain. I am going to be confirming that R2 is set to 680 Ohms.
I am using a Denon DL103. My understanding is that it has .3 mV output.
All the information I’ve found regarding gain on this cartridge says I should be aiming for 60 dB.
I’m assuming that is just the gain of any phono amplification used prior to any preamp gain.
My first stage of amplification after the 103 is a ZYX CPP-1 head amp I found used.
I was under the impression that this ZYX head amp had 20 dB of gain, but it appears I was misinterpreting the information I found for it and it actually has 26 dB of gain.
I believe the combination of the 103, ZYX and VSPS was working pretty well previously when I was using it with a Salas DCB1 based preamp I had built.
The DCB1 was modified on the outputs with some Jensen transformers that gave it only about 6 dB of gain.
The preamp I’m currently trying to use is an old Audible Illusions 2D. According to the manual it has 30 dB of gain in the line section.
I am not using the preamp’s phono section. I plug the VSPS in to the AUX line.
Regardless of this preamp’s line stage gain, I am not getting a good quality signal from my phono source.
Essentially, I can turn the preamp volume pot up to about 50% before I get loud feedback through the system.
Even prior to that point I am getting excessive hiss and flutter noise…probably as soon as 33% of volume. Setting this level barely approaches what I would consider a hearty room filling listening session.
I’m thinking that the excess gain that is being created before the signal reaches the preamp line stage is the problem?…at 66 dB?
For reference, I am currently using a pair of Quicksilver Horn Mono amps that are driving a pair of Tannoy System 15 DMTii speakers.
The speakers have a sensitivity of about 101 dB and are similar to other horn speakers and drivers that I have used.
The amps are designed to be used with this type of high sensitivity speaker and are rated at 25 watts which is similar to most other amps I’ve built and used.
The preamp is not the best nor does it have an amazingly low noise floor, but I have no problem getting excellent performance and incredible sound levels with a full 2V signal from a digital source like my MacBook.
So my question is about setting the gain of the VSPS in this system or the possibility of making it adjustable.
I’m assuming I need to set the VSPS gain for about 34 dB if I’m understanding things correctly?
You gave a few examples in the BOM for setting gain of the VSPS. I believe R2 @ 220 Ohms results in 50 dB of gain and R2 @ 2.2 k results in 30 dB of gain.
Is there a more accurate way of trying to set the VSPS gain for the 34 dB that I need? Other than guessing the resistor value is mid way between 680 and 2.2k at about 1.5k?
Perhaps measuring voltage in and out of the circuit somehow?
Is it possible to mount a pot at R2 to make it adjustable?…or would that have a negative affect on the sound quality of the circuit?
Am I barking up the wrong tree here and the problem is elsewhere?
Attachments
You have a nicely built VSPS300 there, so it would be a shame to go modding it if there is no real need. 40 dB gain is about what you want as a MM phono stage. For R2, doubling the value decreases the gain 6 dB, 1.4x is -3dB, and there is little point worrying about finer increments. So go from 680 ohms to 1.5k to drop down to around 34-35 dB. That will be enough to let you know if you are on the right track, but I rather suspect this is not the issue here.
Any noise in the circuit is most likely from the head amp. First thing I'd do is double check by replacing the VSPS with another MM stage.
/R
Any noise in the circuit is most likely from the head amp. First thing I'd do is double check by replacing the VSPS with another MM stage.
/R
Richard
im planing my second Emerald.
I have a broken Technics SE-A 808 that i want to use as case, this amplifier came with to transformes that gives me each one 33v, would this work setting C4,5 to 35 or 50V as you sugest on post 125.
And is it possible to use this transformes together? If i connect each transformer on each side of the rectifier board.
Sorry for my spelling
im planing my second Emerald.
I have a broken Technics SE-A 808 that i want to use as case, this amplifier came with to transformes that gives me each one 33v, would this work setting C4,5 to 35 or 50V as you sugest on post 125.
And is it possible to use this transformes together? If i connect each transformer on each side of the rectifier board.
Sorry for my spelling
@daveegg
First, let me quote my earlier post you refer to:
People occasionally ask me if 2x15 V or even 2x18 V secondaries are OK. If you increase the cap voltage rating, yes this is OK.
I'm not sure if your 33 V refers to the secondary transformer winding or the nominal voltage rail of the Technics circuit after rectification. If it's the secondary, i.e. 33 VAC, forget it, that's way too high. If that's the DC voltage, I guess the transformer secondary is 22-24 VAC. You'd need 50 V caps to be safe, and the transistors will run slightly hot, but I guess it's just about OK...
First, let me quote my earlier post you refer to:
Normally the Emerald is specified for 2x12 V secondaries, giving +/-18 V rectified DC for V++ and V--. The caps are rated to 25 V, so all good.
People occasionally ask me if 2x15 V or even 2x18 V secondaries are OK. If you increase the cap voltage rating, yes this is OK.
I'm not sure if your 33 V refers to the secondary transformer winding or the nominal voltage rail of the Technics circuit after rectification. If it's the secondary, i.e. 33 VAC, forget it, that's way too high. If that's the DC voltage, I guess the transformer secondary is 22-24 VAC. You'd need 50 V caps to be safe, and the transistors will run slightly hot, but I guess it's just about OK...
Ok my version of the emerald is nearby finished ;-) I'm waiting for some PSU parts and then I will see how it works.
It started with the rear panel.
After I drilled some holes...
and some soldering and braiding
it was time to find a nice design for the front plate. At least silver on silver was my choice
the three other designs/colors are maybe good for other versions - who knows.
It started with the rear panel.
After I drilled some holes...
and some soldering and braiding
it was time to find a nice design for the front plate. At least silver on silver was my choice
the three other designs/colors are maybe good for other versions - who knows.
Hi Folks,
I went all in after browsing through the thread and reading the information on Richards website and purchased the Emerald, PSU and switchboard kits from Richard in January.
I've gone for the Hammond bare aluminium cases, the 1590D for the power supply and 1590F for the phono stage.
I'm using a 19mm vandal proof switch for my on/off switch on the power supply, and a similar style LED will be used on the phono stage to indicate power status.
Next steps are to draw out the design for my phono stage, and also purchase a new soldering station as my Antex 30W was having trouble with the heavy pads on the PSU board (currently looking at a Aixun T3A, a JBC clone with T245 hand tool).
I've spent a great deal of time looking for a 3-pin DIN connector style plug and socket for the umbilical cord, the ones I have chosen were sourced from CPC in the UK and feature a lock ring to prevent disconnection. I'm using some twisted braid, table lamp style cord as the umbilical cable for a bit of style!
I have purchased a can of black wrinkle finish paint which I was going to use on the cases but not sure at the moment as I like the bare aluminium look also.
Looking forward to building the phono stage soon
Thanks
I went all in after browsing through the thread and reading the information on Richards website and purchased the Emerald, PSU and switchboard kits from Richard in January.
I've gone for the Hammond bare aluminium cases, the 1590D for the power supply and 1590F for the phono stage.
I'm using a 19mm vandal proof switch for my on/off switch on the power supply, and a similar style LED will be used on the phono stage to indicate power status.
Next steps are to draw out the design for my phono stage, and also purchase a new soldering station as my Antex 30W was having trouble with the heavy pads on the PSU board (currently looking at a Aixun T3A, a JBC clone with T245 hand tool).
I've spent a great deal of time looking for a 3-pin DIN connector style plug and socket for the umbilical cord, the ones I have chosen were sourced from CPC in the UK and feature a lock ring to prevent disconnection. I'm using some twisted braid, table lamp style cord as the umbilical cable for a bit of style!
I have purchased a can of black wrinkle finish paint which I was going to use on the cases but not sure at the moment as I like the bare aluminium look also.
Looking forward to building the phono stage soon
Thanks
Just to let you know that there are 10 more Emerald PCBs available, which I can send out to Europe countries which can't be posted by RJM via air mail only. I forgot to clear my basket on my last order of PCB's from my provider in China that's why they are on stock now. 12€ a pair including shipping to Germany only. Other Europe countries 10€ a pair plus shipping.
@EoA Lol. Still, your mistake will hopefully be useful - nothing has really changed on the shipping situation at Japanpost unfortunately.
@dlknight That looks great! The power button is a good aesthetic match for the raw aluminum chassis. As for the umbilical connectors I recommend XLR as being the easiest to source, though there are still plenty of old-style multipin feedthoughs to choose from if you search.
@dlknight That looks great! The power button is a good aesthetic match for the raw aluminum chassis. As for the umbilical connectors I recommend XLR as being the easiest to source, though there are still plenty of old-style multipin feedthoughs to choose from if you search.