Phono preamp-modules

[hjames]

Well, turntable inputs are designed for low voltage signals, much lower than "line level" inputs like cassette, CD, DVD, etc ...
So first, the TT input levels would be overdriven by other devices.
Second, TT inputs have an RIAA curve to compensate for the curve used when recording the vinyl. Think of it sort of like Dolby is for tape. Even if you pad down your auxiliary signal to run it into the TT input, the signal will get distorted from the RIAA curve.

Best to get an external switcher if you need more inputs.

Only slightly OT

my C-4 has 3 TT i/p's . I dont use vinyl anymore , so they are wasted. NE1 know what it takes to convert a phono input to just an AUX ??

[SEAWOLF97]

Well, turntable inputs are designed for low voltage signals, much lower than "line level" inputs like cassette, CD, DVD, etc ...
So first, the TT input levels would be overdriven by other devices.
Second, TT inputs have an RIAA curve to compensate for the curve used when recording the vinyl. Think of it sort of like Dolby is for tape. Even if you pad down your auxiliary signal to run it into the TT input, the signal will get distorted from the RIAA curve.

Best to get an external switcher if you need more inputs.

Had another receiver about 10 years back with too many TT's i/p's also. My tech guy who is now gone said "bring it in, the internal mod is easy..I'll do it for free". so thats the question. What was he going to do ?

[Hoerninger]

For the price I like the Parasound and NAD units below, though still expensive relatively speaking. Not rated as highly as the Lehmann, but 1/4th the price. Both will accomodate MM and MC cartridges.

Thank you for your reply. Parasound and NAD I did not know. The NAD looks really nice ...
The Lehmann reminds me that there was a soldering iron too ...
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Peter

[hjames]

Had another receiver about 10 years back with too many TT's i/p's also. My tech guy who is now gone said "bring it in, the internal mod is easy..I'll do it for free". so thats the question. What was he going to do ?

Thats hard to say, exactly, - but depending on circuit design it could be as simple as soldering a couple of jumpers to the circuit board to bypass a gain stage and the phono EQ.

Easy for him to say

[Hoerninger]

NE1 know what it takes to convert a phono input to just an AUX ??

Don't know "NE1" but this little circuit in front of the PHONO input will convert any LINE.

[NE1 = anyone?]
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Peter

[X_X]

Only slightly OT

my C-4 has 3 TT i/p's . I dont use vinyl anymore , so they are wasted. NE1 know what it takes to convert a phono input to just an AUX ??

Yes, I do. But, I would only 'convert' the RCA jacks.

A true Phono input means there is a step up and a form of RIAA EQ. Clip this out of circuit by removing the wires leading to the input jacks. Double up an AUX from your other AUX inputs and wire it in where the phono once was.

Depending on the circuit of your preamp, there might be a load removed from the power supply when you bypass the phono leg and a "dummy" load (in the form of resistors) may need to be implemented to keep it balanced. I would have to see the amp, and pref a schematic to say for certain.

Nate.

[SEAWOLF97]

now a further wrinkle is...

I have 2 controls for phono cartridge load

the first is marked in pF and ranges from 100-470

second is Ohms...marked from 100-100X.

[hjames]

Sure - but the REAL question is - do you NEED that extra input, and if so, what are you planning to use for the signal source?

That info is just for better matching the phono cartridge you might choose to use ... if you physical bypass the gain stage within the amp it becomes moot.

now a further wrinkle is...

I have 2 controls for phono cartridge load

the first is marked in pF and ranges from 100-470

second is Ohms...marked from 100-100X.

[SEAWOLF97]

Sure - but the REAL question is - do you NEED that extra input, and if so, what are you planning to use for the signal source?

That info is just for better matching the phono cartridge you might choose to use ... if you physical bypass the gain stage within the amp it becomes moot.

just using the Nano for a source....have many tunes on MP3 that there is no physical media for.

[hjames]

just using the Nano for a source....have many tunes on MP3 that there is no physical media for.

Sure - on my system I run "Airtunes" streaming from my Mac into the Tape-in port ... if that or any of your other inputs are free its an easier path than reworking a phono input ...

[coherent_guy]

I agree with Ms. James and others, bypassing the phono stage is not very simple and would likely be a major modification. I don't understand Hoerninger's circuit, but it would need to both attenuate the input signal drastically, and perform the opposite RIAA EQ so the net result is flat response. There are other issues with this conversion that just don't make it practical in my opinion.

This may be a "duh" suggestion, but you can use the tape inputs for the Nano.

You can try using a pair of Y cables with one male to two female RCA jacks, and share an input with the Nano and whatever. Just turn off the other source. It will work but occasionally there are little glitches waiting to bug you that might mess it up. It will likely be just fine. Worth a try and Y cables can be had for a few bucks. There are other types, PE has them but their site is down at the moment it seems...

If you are desperate, you can turn another receiver/preamp into a switching unit by connecting your extra sources to it and then run a cable from its tape out into the C4. Choose the desired source by setting the "Tape Out" or "Record Out" to that source on the switching unit. Ignore the volume control, it will do nothing. This adds another preamp stage circuitry in the signal path, but that will only bother the purists (like me) or the golden ears that could hear it.

I'm betting you have an extra piece or two that you could do this with... Let us know how things work out.

[Hoerninger]

... bypassing the phono stage is not very simple and would likely be a major modification. I don't understand Hoerninger's circuit, ...

From left LINE source (Nano) is coming and converted by the circuit to reverse RIAA with the appropriate level, right to PHONO input of amp.
These parts (twice for stereo) can be fitted external in a little box, no mods in the amp are necessary, or this little circuit is built into the amp between connectors (cinch) and the pre-amp.
With this modification the PHONO input can be used as AUX with a minimum of technical understanding.

Other solutions for the Nano are possible of course.
___________
Peter

[Zilch]

Sure, fine, but we need the asterisked info....

[That'd be three nanos go there, no? ]

[Hoerninger]

Sure, fine, but we need the asterisked info....

Oh Mann, you can't get 3nF, take 2,2 nF and 820 pF in parallel. - typically marked 2n2 and 820.
[I do not have no iPod ]
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Peter

[coherent_guy]

[quote=Hoerninger;160262With this modification the PHONO input can be used as AUX with a minimum of technical understanding.

Peter[/quote]

I see, I was just surprised that such a simple circuit could perform the inverse EQ, when there is much more going on in a phono preamp. But it's great that it works! Not my style, but interesting. I'm a pure (ha) digital person, no TT's in my system, inexpensive ones are not good enough sonically for me, and I won't/can't afford a really good TT set up with all the necessities.

Are you familiar with Vincent components, they have a phono preamp at the retailer I provided links to in an earlier post. They look good to me, but I've never heard them.

Also, "NE1" is a shorthand for "anyone", get it?

Anyway...

Our friends at PE have an inexpensive phono-pre that may be good, made by ART for $49, check it out:

http://www.partsexpress.com/pe/showd...number=245-876

Seawolf, this is the part I mentioned from PE:

http://www.partsexpress.com/pe/showd...number=091-510