I suspect the answer to this will be simple. I was able to get a hold of a nice vintage preamp/power amp (Denon PRA-1000/Denon POA-1500), and the brand new turntable I ordered (Pioneer PL-990) has, unfortunately, no switch to bypass the built-in preamp. I suspect I could get much better audio quality by bypassing the TT's preamp and sending that signal to the PRA-1000's phono input. I have an electronics background and I'm reasonably good with a soldering iron.
Since I'm unfamiliar with TT's circuitry, my question is: what would it take to skip the built-in pre-amp? Just connecting the output of the arm to the RCA connectors instead of sending that to the board? Is that only two cables? I haven't opened the TT yet because I'd like to verify how to do this before voiding its warranty. I would really appreciate any input from someone familiar with this procedure. I could consider also installing a switch to flip between phono output and line output, but something as simple as skipping the built-in pre altogether would do.
Also, once I successfully do this, how do I know whether I should use the Phono-MC or Phono-MM input on the pre?
Thanks!
Since I'm unfamiliar with TT's circuitry, my question is: what would it take to skip the built-in pre-amp? Just connecting the output of the arm to the RCA connectors instead of sending that to the board? Is that only two cables? I haven't opened the TT yet because I'd like to verify how to do this before voiding its warranty. I would really appreciate any input from someone familiar with this procedure. I could consider also installing a switch to flip between phono output and line output, but something as simple as skipping the built-in pre altogether would do.
Also, once I successfully do this, how do I know whether I should use the Phono-MC or Phono-MM input on the pre?
Thanks!
The manual that comes with the turntable should state what sort of cartridge is fitted. MC types are generally quite a bit more expensive than MM types so an MM type seems more likely.
There is a theoretical SNR advantage to having the pre-amplifier right there in the turntable. Are you sure that the one fitted to the table is a dog? Most likely if this was a dirt cheap table and the pre-amp design was an afterthought.
If you decide you want to use the pre-amp in the amplifier disconnect the internal pre-amp from both the output jacks and the cable from the tone arm and run the tone arm connections directly to the jacks. Watch out for noise pick up as the signal levels are quite low.
There is a theoretical SNR advantage to having the pre-amplifier right there in the turntable. Are you sure that the one fitted to the table is a dog? Most likely if this was a dirt cheap table and the pre-amp design was an afterthought.
If you decide you want to use the pre-amp in the amplifier disconnect the internal pre-amp from both the output jacks and the cable from the tone arm and run the tone arm connections directly to the jacks. Watch out for noise pick up as the signal levels are quite low.
Based on the price of the table there probably was not a huge amount of spare cash for the phono stage so you probably will be better off bypassing it. Try it first and make sure the table functions properly for a couple of weeks before voiding the warranty.
It definitely uses a moving magnet (mm) cartridge so use your MM inputs. Hopefully the equipped cartridge is a p-mount type so that you can easily upgrade to something a bit better when the stylus wears out. (Edit: Based on reviews apparently not)
It definitely uses a moving magnet (mm) cartridge so use your MM inputs. Hopefully the equipped cartridge is a p-mount type so that you can easily upgrade to something a bit better when the stylus wears out. (Edit: Based on reviews apparently not)
Hi,
YMMV but the inbuilt preamp in the Pioneer PL-990 is hardly
a show stopper compared to the fact its a very basic cheap
turntable, and its nowhere near the sort of turntable to go
go with the Denon stuff, by a very long way, IMO.
Used Acoustic Research EB101 (or a variant) used with
the Red Ed elliptical Ed Saunders Red Ed Cartridge
would be my sort of starting point with the Denons,
if you want vinyl to compete in any sense with CD.
rgds, sreten.
YMMV but the inbuilt preamp in the Pioneer PL-990 is hardly
a show stopper compared to the fact its a very basic cheap
turntable, and its nowhere near the sort of turntable to go
go with the Denon stuff, by a very long way, IMO.
Used Acoustic Research EB101 (or a variant) used with
the Red Ed elliptical Ed Saunders Red Ed Cartridge
would be my sort of starting point with the Denons,
if you want vinyl to compete in any sense with CD.
rgds, sreten.
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Sreten has a good point, however I figured if you were new to vinyl this would be an ok starting point. You have read the reviews I assume and are familiar with its limitations.
Any decent fully shielded interconnect off of eBay should work fine, there are acceptable and quickly available cables from Radio Shack. Avoid the expensive name brand cables at Best Buy and elsewhere. You are mostly paying for the name on the box.
No specific recommendations as I make most of my own cables specific to purpose.
Any decent fully shielded interconnect off of eBay should work fine, there are acceptable and quickly available cables from Radio Shack. Avoid the expensive name brand cables at Best Buy and elsewhere. You are mostly paying for the name on the box.
No specific recommendations as I make most of my own cables specific to purpose.
Hi,
You can modify the turntable, its not complicated, but its
essentially pointless, the inbuilt RIAA is not the problem.
Fundamental sound quality will barely change.
rgds, sreten.
And yes, the current cables fitted may not work
well if you bypass RIAA and go into a RIAA input.
TBH the fact you can't bypass the internal Pioneer
RIAA is a very big clue as to its ambition level.
Just accept it for what it is IMO.
You can modify the turntable, its not complicated, but its
essentially pointless, the inbuilt RIAA is not the problem.
Fundamental sound quality will barely change.
rgds, sreten.
And yes, the current cables fitted may not work
well if you bypass RIAA and go into a RIAA input.
TBH the fact you can't bypass the internal Pioneer
RIAA is a very big clue as to its ambition level.
Just accept it for what it is IMO.
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Pioneer PL-990 Turntable Manual - Vinyl Engine
it uses a TA7325P opamp. in a 9-pin SIP. It is single supplied by a un-regualted PS
it uses a TA7325P opamp. in a 9-pin SIP. It is single supplied by a un-regualted PS
Well, anything is possible, and "bypassing" the rather low-end preamp is actually very simple, provided you can wield a soldering iron successfully and work with the very delicate tone arm cables. It is largely a matter of disconnecting the wires coming from the tone arm from the printed circuit board sfter establishing, which of the (hopefully screened) wires is the left and which the right one. As you have no longer an anchoring point for those tiny wires, you could fit a suitable connector to the rear of the plinth, where you could solder the wires directly to the pins. Personally I have done this by using a female XLR connector and used it as originally intended - as a turntable audio connector (mainly for broadcasters) ! The name gives this original purpose away: L=left, R=right and X=common (ground). Now you have a connector for an easily detachable cable, which you can experiment with. The built-in preamp you could leave in place but deactivate, if it has its own transformer - just disconnect the cable to the primary winding. The whole exercise will sadly not make your turntable sound a lot better, but you will probably benefit from less noise and a better frequency response due to a more accurate equalization.
A further refinement could be to fit a small dpdt switch to the back of the plinth, and connect the common (usually middle) tags to the preamp input, one side of the switch to the XLR's L and R. pins (pins 2 and 3 respectively) and two 4k7 resistors to the other side of the switch to form a dummy input load, if the cartridge is disconnected from the internal preamp. This prevents increased noise of open inputs, should the preamp be connected to a power amp without being connected to the pickup cartridge. Mark the switch as "Preamp On" and "Preamp Off". Of course, in this case the preamp power must be permanently on. This wat you can compare the performance of the preamps in the turntable and the amplifier.
Hopefully, all this is not too confusing...
A further refinement could be to fit a small dpdt switch to the back of the plinth, and connect the common (usually middle) tags to the preamp input, one side of the switch to the XLR's L and R. pins (pins 2 and 3 respectively) and two 4k7 resistors to the other side of the switch to form a dummy input load, if the cartridge is disconnected from the internal preamp. This prevents increased noise of open inputs, should the preamp be connected to a power amp without being connected to the pickup cartridge. Mark the switch as "Preamp On" and "Preamp Off". Of course, in this case the preamp power must be permanently on. This wat you can compare the performance of the preamps in the turntable and the amplifier.
Hopefully, all this is not too confusing...
This website says XLR means "X series", which later incorporated a latch (L) and then rubber insulation (R), leading to the acronym "XLR". Other sites seem to agree, although the Rubber part is now omitted so what we call an XLR should really be just an XL.MIDIMOGUL said:
Bypassing the Internal Amplifier
My turntable, Numark TTX-USB has a Phono/Line switch underneath. Is this the switch that will bypass the internal amplifier? The handbook states the following:
This switch should be set to the proper level depending on the type of input the turntable is connected to. PHONO is used with traditional turntable inputs on older receivers or where PHONO is stated. LINE level allows the TTXUSB to directly connect to modern electronic inputs such as computers, home stereos, and mixers.
Right now I use an old, cheep combo that, I think, has its own built in amplifier, and connect the turntable to the aux because there is no phono port on the back but there is a phono button in the front because the combo also has a phonograph. Is the button to bypass the internal amplifier of the turntable and which way to turn it off: Phono/Line?
My turntable, Numark TTX-USB has a Phono/Line switch underneath. Is this the switch that will bypass the internal amplifier? The handbook states the following:
This switch should be set to the proper level depending on the type of input the turntable is connected to. PHONO is used with traditional turntable inputs on older receivers or where PHONO is stated. LINE level allows the TTXUSB to directly connect to modern electronic inputs such as computers, home stereos, and mixers.
Right now I use an old, cheep combo that, I think, has its own built in amplifier, and connect the turntable to the aux because there is no phono port on the back but there is a phono button in the front because the combo also has a phonograph. Is the button to bypass the internal amplifier of the turntable and which way to turn it off: Phono/Line?
sreten:
So, connecting the turntable to the aux of the combo unit and moving the Phono/Line switch of the turntable to Line will disconnect the internal amplifier of the turntable and the audio from the cartridge will go through the amplifier of the combo unit? Am I correct in reading what you wrote in this manner?
So, connecting the turntable to the aux of the combo unit and moving the Phono/Line switch of the turntable to Line will disconnect the internal amplifier of the turntable and the audio from the cartridge will go through the amplifier of the combo unit? Am I correct in reading what you wrote in this manner?
Thanks for all the advice.
After some back and forth with Help of the turntable distributor, to bypass the phono amp. of the turntable I have to move the switch on the turntable to Line and connect it to the Aux of the amplifier. The Aux may also be called Line input of the amplifier or any other designation but they are all Aux inputs pending confirmation by the amplifier manufacturer. This is how I read the response from the TT people.
Unfortunately, the combo that I am using does not have a specific Phono input in the back so I can check Phono to Phono connection.
This combo has its own turntable, radio, and tape deck. There are "buttons" on the front to go from one to the other but on the back there are only outputs for the loudspeakers and one Aux/CD input.
When I connect the turntable directly to the speakers very low sound come out of either the cartridge or the speakers whether the switch is on Phono or Line.
When going through the Combo, the only time when there is any volume is when the tt switch is on Line and nothing when on Phono. Unfortunately, I cannot test a Phono to Phone connection. Right now I'm in the process of getting a iAmp. or a preamp and amp.
Anyway, after a lot of reading and still doing a lot of reading, my upper limit seems to have vaporized. The Quest goes on.
After some back and forth with Help of the turntable distributor, to bypass the phono amp. of the turntable I have to move the switch on the turntable to Line and connect it to the Aux of the amplifier. The Aux may also be called Line input of the amplifier or any other designation but they are all Aux inputs pending confirmation by the amplifier manufacturer. This is how I read the response from the TT people.
Unfortunately, the combo that I am using does not have a specific Phono input in the back so I can check Phono to Phono connection.
This combo has its own turntable, radio, and tape deck. There are "buttons" on the front to go from one to the other but on the back there are only outputs for the loudspeakers and one Aux/CD input.
When I connect the turntable directly to the speakers very low sound come out of either the cartridge or the speakers whether the switch is on Phono or Line.
When going through the Combo, the only time when there is any volume is when the tt switch is on Line and nothing when on Phono. Unfortunately, I cannot test a Phono to Phone connection. Right now I'm in the process of getting a iAmp. or a preamp and amp.
Anyway, after a lot of reading and still doing a lot of reading, my upper limit seems to have vaporized. The Quest goes on.
Just buy a better cartridge for your current table.
If its not giving rumble etc then it should be fine.
I don't have an electronics background and I never used a soldering iron, however, I was able to add this switch: Pioneer PL-990: You can add a PreAmp bypass Switch- Vinyl Engine
LP Gear Improved stylus for Pioneer PL-990 turntable
Code: PTPL0990I
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