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5m interconnect post phono pre-amp

Bossk128

Prominent Member
Hi all,
We're in the process of deciding on some new AV furniture. There isn't room for the record player. I like the idea of a floating shelf, but long interconnects to another piece of furniture is easier (it's a lathe and plaster wall and i have no confidence in it's load bearing ability, well, my DIY skills....).

Is it a problem to have say a 5m run of good quality stereo interconnects AFTER the phono preamp, to the hifi preamp? I'm assuming that after phono preamp the signal is like any other component, e.g. CD. I can't run balanced cables, and the cable run is along the LFE interconnect, and power cables possibly.

Feasible or a disaster?
 

BlueWizard

Distinguished Member
5 meter or a bit over 16 feet, that's pretty far.

If you have an external PHONO Pre-Amp, that can, in a sense, act as a relay. Just to illustrate, you could have 6 feet of wire from the turntable to the Phono Pre-amp, and another 6 feet from the Phono Pre-Amp to the Stereo. That is not 12 feet, functionally that is only 6 feet, as I said, the pre-amp acts as a relay. (Those numbers are strictly for illustration).

Whether you can do that with two 8 foot (2.5m) cable or not is unclear.

I too have my turntable a bit far from my amp, but in my case, I've simply patched two 1 meter cables together. It seems to work fine.

The problem is in trying to determine when the length of low level cable gets long enough that the resistance, capacitance, and inductance start to effect the sound quality. Also, the longer the cable, the more it acts as an antenna and is likely to pick up noise from the air. Most likely electrical power line noise (50hz).

The first thing you have to wonder is if you can actually find 8 foot (2.5m) low level signal cables. Then I would recommend getting high quality cables, though, one doesn't have to go crazy on the price. Just not cheap cables.

Most of the RCA-RCA cables I find are in the 1 meter to 1.5 meter range. However, you can have cables custom made in any even meter length -

QED Performance Audio 2 Custom-Made Stereo Phono / RCA Cable - By Brand - AudioVisual Online - Home Cinema and Hifi Specialists

In your case probably a 2 meter from the Turntable to the Pre-amp and 3 meters from the Pre-amp to the stereo.

It is possible to get RCA-RCA cable as long as 3 meters (9.8ft), but short of custom made, that is about the longest I can fine on a quick check -

QED Qunex 1 Stereo Phono / RCA Cable 3m - By Brand - AudioVisual Online - Home Cinema and Hifi Specialists

Fisual Super Pearl Stereo Phono / RCA Cable 3m - By Brand - AudioVisual Online - Home Cinema and Hifi Specialists

The underlying question isn't - can it be done, you can do anything. The true underlying question is - how well will it work. That is a bit more unpredictable. I suspect, if you have good quality cable, and the quality of the power line voltage in your house is good, it will likely work acceptable well.

Though that also depends on the quality of your equipment. With a typical consumer stereo (or audio system) a slight compromise in sound quality is not so noticeable, but with a very high end system, everything is noticeable.

If you have an external Phono Pre-Amp, as you imply, what comes out of it is new fresh signal, so it can act to boost and relay the signal to the amp. If you place is set up so the Phone Pre-Amp can be near the midway point, then you really only have 8 feet (2.5m) of cable to worry about. I don't think that will be a problem.

If you have to split the lines, say rather than two 2.5m cables, you have to use a 2m and a 3m, put the shortest cable on the turntable. The signal from the turntable is extremely low and very susceptible to noise, so it should have the shortest and highest quality cable.

I would give some serious thought to this plan though. If you can find an alternative to the turntable being so far away, the shorter distance would be preferable.

As to wall mounting a shelf for the turntable, like anything, this has advantages and disadvantages. When I was young, I lived is what is best described as a "Party House". I had my turntable on a floor stand (equipment stand), my roommate has his mounted on the wall. To keep my turntable from skipping people had to walk delicately. Not tip-toe, just mindful. However, relative to my roommate's turntable, people had to be careful not to SLAM the front door. When the door was slammed, that shock wave was transferred through the walls and made the turntable skip. Though bear in mind, this was a wood frame house. This reaction is far less likely in a stone, mortar, brick house.

As to the wood frame studs with plaster over lath, that's not as bad as you think. I bought a Stud Finder, but not a fancy electronic one, this is a simple magnet floating in a plastic frame. To fasten the Lathe to the Studs, they use nails. That means at every vertical stud, there is a long vertical row of nails. Slide the plastic frame along the wall, and when the magnet finds a row of nails it points at the metal. Re-check above and below to make sure you are actually on a stud, and not a random bit of metal in the plaster, and you've found a Stud. If you fasten the wall shelf to the studs, you can be sure it will support substantial weight.

This little magnetic stud finder was only about £2. I mean it is just a plastic frame with a magnet on a pivot, so nothing fancy.

STANLEY Hand Tools : 47-400 - Magnetic Stud Finder

Stanley 47-400 Small Magnetic Stud Finder with Marking Notch | eBay

There are shelves just for turntables, and I think they are intentionally made to fit right on the stud frame centers, which I believe is about 430mm center to center.

Superfi - APOLLO WT1 SE HIFI WALL SHELF

Pro-Ject Wallmount IT 1 Turntable Shelf

Pro-Ject Wallmount IT 2 Turntable Shelf

Rega Turntable Wall Shelf - (Black) | eBay

Custom Design Wall Mounted Turntable Support - Black Frame, Clear Glass Shelf | eBay

I'm currently using 2 meters on my turntable, and that seems workable. So, depending on the circumstances, if you put 2 meter between the turntable and the Phono Pre-Amp and 3 meters after the Phono Pre-Amp, I suspect, that would be workable.

However, I'm not sure about a full 5m run of a single cable. That is likely to work, I just can't predict to what degree it will compromise the signal, perhaps none, perhaps ... more than none.

If you do use a full 5m run, then it is best if that run is after the Phono Pre-Amp, where the signal is stronger. You would not want 5 meters connected directly to the turntable. This direct TT signal is about 100 times smaller than the Line Level of the Pre-Amp out.

I'm sure I have not truly answered your question, but perhaps I have added some helpful perspective.

Steve/bluewizard
 
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Bossk128

Prominent Member
Thanks BW, you've confirmed a few of my concerns. I was banking on the fact that the phono preamp would help against signal loss. If I could go balanced I'd be less concerned.

I'll price us the interconnects, it may be expensive in which case my diy will be tested!
 

Bossk128

Prominent Member
Thans for the links, food for thought. I'm really looking for a cream one, they must be out there!
 

Glen B

Established Member
For many years I have run 15ft RCA interconnects between my preamp tape outs and computer when making LP to CD transfers. I have not had any noise pickup issues.
 

BlueWizard

Distinguished Member
Glen, that was Tape Out to Computer. That is standard Line Level; the output of an MM cartridge is about 100 times less and more susceptible to noise.

However, he has a PHONO Pre-Amp, if he positions that a reasonable distance from the turntable and uses it to relay the signal to the Amp, I doubt he will have any problem assuming reasonable cables and assuming no other as of yet unknown factors.

However, you have established that at 15ft to 16ft you are not outside the working range of LINE LEVEL signals. That's good to know.

He could place the Phono Pre-Amp somewhat close to the Turntable, say about 1 meter, and be reasonably certain that the Pre-Amp would drive the signal the remaining 12ft to 13ft to the amp.

I'm currently using 2 meters direct from the Turntable to the MM Phono Input on my amp, that seems to work reasonably well. So, it seems the Original Poster does have a workable range of options open to him, if he is not able to move things closer together.

Steve/bluewizard
 

Glen B

Established Member
Glen, that was Tape Out to Computer. That is standard Line Level; the output of an MM cartridge is about 100 times less and more susceptible to noise.

However, he has a PHONO Pre-Amp, if he positions that a reasonable distance from the turntable and uses it to relay the signal to the Amp, I doubt he will have any problem assuming reasonable cables and assuming no other as of yet unknown factors.

Steve/bluewizard

I am puzzled. This is the second time you have responded to one of my posts when I said nothing incorrect. The OP's question was whether there would be a problem with a 5-meter interconnect run "AFTER the phono preamp". The signal output from a preamp "tape out" is the same level as the output of an external phono preamp, so no problem there.
 

BlueWizard

Distinguished Member
I never said you said anything incorrect. In fact I thanked your for adding that additional perspective. Just because I respond to your post does not mean I am not directing information at the Original Poster. My goal is for him to have as much perspective as he can in making a workable decision to solve his problem.

You are feeding LINE LEVEL into 15 feet of wire. Good, we know that works. However, the OP is feeding a combination of very low level signal combined with standard Line Level, and the goal is to find a workable combination for HIM.

Your input added valuable perspective to the discussion. Good information to have, good information to know. I added more perspective. Not everything is about you.

5 Meters is a long run, anything he can do to minimize that, without compromising the sound, is to his benefit. But, it is nice to know that a 5 meter run on its own is workable. Which is precisely what you established for us - THANKS!

Steve/bluewizard
 

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