Pre Amp for Phono - AVS Forum
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Old 06-26-2013, 11:41 PM - Thread Starter
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Hope this goes in the right spot.. Im new here and receintly got back into vinyl and remodled a room thats a perfect listeneing room.. its 19x23 and has a nice 70 inch 857 sharp on the wall.. Audio is Bowers and Wilkins 685, front HTM62 center and 686's rear also a revel sub thats wireless.. O' and a marantz sr5007 receiver.. so the question... theres been a l lot of talk about phono pres and phono stages ,, tube or not tube,, cheap or not cheap,, so"" I have a new Denon 300f with grado gold prestige cartridge.. The denon has a built in phono pre as well.. So what I was thinking was to get my records playing close to the lever of other audio and inhancing the sound some,, I would like to pull out of my recording rig a Aphex 207D.. its a tube microphone pre and also a instrument pre.. Since the Denon already had the correct eq going on its pre I just keep that on and runleft and right to the Aphex tube pre and pad it down . Also switch to -10 on the output for comercial line level.. The front gives me gain control so I can add some tube gain to it and get it louder... So' is this a problem,, I dont see why this wouldnt work and it might sound pretty good since Ive already corrected the phono stage with the built in pre for the Denon.. Im just boosting the signal with a Tube pre.. This might also solve my problem that I want to run a longer length of cable...Well?
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Old 06-26-2013, 11:47 PM - Thread Starter
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I ran about 40 feet of rca so I could put my table on a different side of the room, and then reading that its a big no no,. So do you all think by using that tube pre with the -10 output that will alow me to use the exteded rca
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Old 06-27-2013, 06:16 AM
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There are potential problems with running such a long unbalanced cable.

It would be far preferable if you could go to a balanced cable for that distance.

On the other hand, if what you are doing has not resulted in excessive hum or noise...if it ain't broke, don't fix it.
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Old 06-27-2013, 07:34 AM
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Quote:
Originally Posted by stickstome2 View Post

I ran about 40 feet of rca so I could put my table on a different side of the room, and then reading that its a big no no,. So do you all think by using that tube pre with the -10 output that will alow me to use the exteded rca

I hate to break your bubble but the Aphex isn't a tube preamp. For all the world it looks like a SS preamp with a tube EFX circuit. If you like the EFX, 'nuff said.

I don't see a problem running an unbalanced line from/to the Aphex as long as you don't have problems with hum or noise.
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Old 06-27-2013, 06:00 PM - Thread Starter
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Your right the input and front end of the aphex is as but the output gain is tube.
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Old 06-28-2013, 07:33 AM
 
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What's the point?

Why don't they mention the type of tubes it uses?
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Old 06-28-2013, 10:01 PM
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Hi Stickstome,
Quote:
Originally Posted by stickstome2 View Post

.. its a tube microphone pre and also a instrument pre..
If the Aphex is meant for microphone and instrument input, then the line level output from the turntable's preamp might be too strong for it. If the Denon's output saturates the Aphex's input, you will hear distortion. So if it sounds OK to you, you should be fine.

However, I wonder why you're not getting enough output from the Denon's preamp. Maybe there's a problem that warrants a call to tech-support.
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Old 07-01-2013, 05:27 AM - Thread Starter
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Actually the aphex 207d does mention what tube it uses on the site but I don't remember right now, and mark maybe right if the denon pre is not doing its thing correctly then it could be a warranty deal. But to the other post about the input being so strong, the aphex has a input pad for strong signals driven by a condenser or dynamic mic , so I'll just pad it down. As to why im doing it, is because I would like a constant regular volume from all my inputs when I switch from Internet radio, Sirius, Apple TV etc. when I go to play LP's I have to almost double the volume to match everything else
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Old 07-01-2013, 06:10 AM - Thread Starter
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Oh yah the denon 300f which is new has a new grado gold prestige cart put on at the store and they also aligned it with a table protractor for me. They set up lots of tables and carts ,so I feel they did it right. I have another cheaper ion player that was 99 dollars I'll try that on and see if it puts out more output, remember the goal is just boost the output from the table as to get close to what other music is and I know moder day stuff is just plain too loud, but I figure if I already have the correct riaa pre from the denon than I'll just run it through anothe tube gain and see if I can increase and get a better sound from the aphex .
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Old 07-01-2013, 06:29 AM - Thread Starter
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12AT7 dual triode is the tube on the out out gain. It also has a miclim button for that extra protection from input peaks. Also this was a 700 dollar unit that sitting around. So I might as well try it. Tell what's the difference between me buying and a 1000 dollar tube phono pre with output gain, versus using the riaa pre built into the table And adding another tube pre with input protection and a tube output gain?
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Old 07-01-2013, 03:30 PM
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Hi Stickstome,
Quote:
Originally Posted by stickstome2 View Post

Oh yah the denon 300f which is new has a new grado gold prestige cart put on at the store and they also aligned it with a table protractor for me.
A different cartridge . . .

The original Denon cartridge was a moving-magnet type, whereas the Grado prestige is a moving-iron type. They have different output voltages, with the Grado putting out twice the voltage than what the Denon would put out (which sounds backwards from your symptoms).

So I suspect the preamp inside the turntable has some form of adjustment to accommodate different types of cartridges, and that your dealer simply hasn't set it correctly.
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Old 07-01-2013, 09:10 PM - Thread Starter
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hmm, i didnt know the built in phono stage was adjustable
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Old 07-01-2013, 11:49 PM
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Hi Stickstome,
Quote:
Originally Posted by stickstome2 View Post

hmm, i didnt know the built in phono stage was adjustable
It might not be adjustable, but that would be pretty lame.

The sensitivity of different cartridges can be all over the map. My preamp allows you to set the phono-input's sensitivity to 2 millivolts, 4 millivolts or 8 millivolts. It also allows you to set the input impedance to 30 kOhms, 50 kOhms or 100 kOhms. I don't expect the Denon to be that flexible, but it also shouldn't be fixed at one level.
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Old 07-02-2013, 05:09 AM - Thread Starter
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Ah, thank you, I'll have to remove the platter and do some inspection . The only thing I really saw was just the switch for turning the built in pre on or off. And in the instructions I don't anything about make any adjustments. But good point I'll definitly check.
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Old 07-02-2013, 07:52 AM
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So-to get back to the original issue. If the Turntable has a built in preamp that brings the signal up to Line Level audio, you should not need another preamp to push through 12-20 feet of good qualitty shielded cable. The concern with the cable length should not be signal attenuation, but hum/noise pick-up. Addition of amplifier stages can only degrade an analog signal's fedelity, no matter how physically "perfect" the amp is. If the Turntable amp has Line Level out, just run the cables straight to the Main Amp and see what you get.

How long is the cable run? If it can be reduced by moving the turntable, that may be the best option.

Also, I am sure you realize, if you do decide to use the additional pre-amp, it needs to be on the turntable end of the cable.
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Old 07-02-2013, 11:12 AM - Thread Starter
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Yes it will be on the table side of the chain. The reason is I would like to boost the volume to get closer to that of my everyday stuff . And I know it's way too loud how they produce now , but I thought the tube gain section might make it sound a little better at the same time. Also the pre ran RCA cable is about 30 to 35 feet . So as of right now I'm not using it.
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Old 07-02-2013, 11:15 AM - Thread Starter
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Lots of people on here use tube or ss pre amps for there phono stage. I'm just using the internal built in for the correct RIAA curve and then padding the signal down to acceptable levels for the tube pre. The only thing I can do is try it and see how it goes
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Old 07-09-2013, 11:03 AM - Thread Starter
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Problem solved. However the tube pre didn't do what I thought it would do. So I just added an inline eq with output volume and turned it up to match closely what other sources are playing at and it sounds great.
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