Graham Slee FAQ : Frequently Asked Questions

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Era Gold MKV, Elevator EXP, Gram Amp 2 SE, Solo, Jazz Club, etc. ...we have a phono preamp stage or headphone amplifier to suit -  Click here

 

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 G R A H A M   S L E E - FAQ

Table of Contents  

Graham Slee Basics - For Low Hum And Noise

Whatever analog system one uses, hum and noise is a common problem that may or may not occur.  Different homes have different electrical equipment used, grounding, positioning, etc.  Hence, the articles below have been written for Graham Slee phono stage owners to fully enhance their listening experience.  Of course, there are some insights from these articles that can be adapted in other analog systems without Graham Slee phono stages.

 

 

Article below by Graham Slee:

 

Our recommendation is to check the chart below and the following comments/recommendations.

 

Power Input ─►

Turntable with MC cart

Normal output Moving Coil

Turntable ground wire to TT Ground only. Never earth a turntable to the mains supply

▼                 ▼
─►      ▼                 ▼      ◄─
▼                 ▼

A FULLY SCREENED turntable interconnect

PSU1 Supply on floor ─►

Elevator EXP

It goes BEFORE the Era Gold

▲▼Phase these two power supplies by turning one power connector round for lowest noise


                       ▼                
◄─

Low capacity fully screened NORMAL interconnect

PSU1 Supply on floor ─►

Era Gold V

11,000 gain at 50/60Hz here!

▲▲Do not place these power supplies on a metallic shelf


                      ▼                
◄─

Low capacity fully screened NORMAL interconnect

Power Input ─►

Your Amplifier

 Connect to Line or Aux
 NEVER THE PHONO INPUT

 

Valve Amplifiers put out a magnetic hum field in the direction of the stacked transformer laminations - usually horizontal - a bit like Saturn's Ring, but invisible. Place any of your phono section equipment in this, and you've asked for it.

All transformers (There is one in your Amp if its supply is mains power) vibrate the structure they're stood on - Yes, even torroidal ones - at the mains (the HUM) frequency. And that will be picked-up by anything microphonic with the 11,000 times amplification you need for a moving coil at 50/60Hz.

This is why the experts have been telling us for at least the last 50 years - to put the turntable section on a different structure, isolated from the main rack or cabinet.   (Soundscape Note: This is indeed ideal, but in many cases impractical in small rooms, so please put emphasis on a good main rack, or good turntable isolation)

Switch-Mode? If you've one of these power supplies in your system - a system with gain in excess of 10,000 that is, you will hear all the residual noise - Sorry, but a "Serves you RIGHT!" is in order here.

There was even an example recently when one self opinionated mains cleaner manufacturer ordered its customers to earth absolutely everything back to the mains cleaner metalwork - thus creating one mother of a hum loop!

Don't forget to uncoil your interconnects too! Many people coil up their interconnects so they're nice and neat, but in doing so they turn the interconnect into an inductor (like a metal detector coil), which WILL pick up hum no matter how well screened it is.

And finally, the soldering we've seen on some really expensive interconnects and arms can only be described as a joke! With us you've got two time served broadcast engineers hand soldering every joint to the only standard that is correct - the right standard. And NOT some employee on a production line who may not have the foggiest idea, or is thinking about what to give the kids for tea.

 

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Graham Slee - More on Hum

Article below by Graham Slee:

Graham, I have hum with your phono stage.  That's odd, it didn't before I shipped it but I can replicate your problem, and if you try my suggestions above under Graham Slee Basics, you'll get rid of the hum.

Whenever I read an enquiry like this it always gets qualified with "but my XYZ stage I was previously using does not" - you just know that's coming.

And why? It's because of a little dodge I'd never quite picked up on before - the XYZ stage has a thing called a "Notch Filter". Set between 50 and 60Hz to cover both USA and European markets, it's a well kept secret. It's also an easily kept secret as not one hi-fi magazine I know spec-tests anything anymore. If it hadn't got this, then the customer would have experienced hum before and would have learned previously that careful positioning cures the problem.

So why don't we fit a Notch Filter? Why? Because it screws the low frequency harmonic structure and that's just one of the reasons our products sound better. Not all but enough other manufacturers use this dodge so that the customer, having little or no record playing experience, can just throw a vinyl front end into his system like you'd do a CD player, and hey-presto! No comebacks.

Add to this, the common practice of bandwidth limiting, and you have a nice phasey sound reminiscent of 70's AM radio reception. So that's where you heard that nostalgic sound before - not at all the nostalgia of vinyl records.

I didn't twig to this when I tested a rather expensive phono stage a few years ago sent to me by The Cartridge Man. I'd been told not to dissect the thing because he wanted to try and sell it, but he felt it didn't sound quite right. I measured the performance and was amazed how well it rejected hum. This was not a balanced input stage, it had virtually no shielding and was housed in a plastic case. How could this be? It also had coiled input wires which makes its input wiring inductive and should therefore be even more susceptible to hum.

I suspected something was out of the ordinary when I tried to measure the input impedance. This is something you can't do with a resistance meter because impedance is an AC thing. What you do is put a resistor in series with the input and sweep through the frequencies and then you can work out the impedance from the ratio of the two output voltages and the value of the resistor.

What threw me was that at a particular low frequency the output disappeared then came back again further on. Like I said, it didn't register - it just bugged me that I couldn't take the thing to bits any further or I'd end up having to buy it. Eventually, time the great healer made me forget, even though I was working on a Notch Filter as part of a design for some American Medical equipment a few months later.

It was only the other day, when re-investigating the old hum problem for a customer, that I tripped right over it. How else could a plastic cased, unbalanced, unscreened amplifier, having a gain of about 11,000 at 50/60Hz, get such a fantastic hum rejection?

Like I say, we don't do such a thing because the phase gets screwed up, not just at the notch filter point, but it extends throughout the audio band meeting up with the phase error from the high frequency end, that being down to bandwidth limiting.

What happens with screwed-up phase is the timing sounds all wrong. It can sound spacey and out of this world, and I guess that's what sells such stages. But when I listened to this stage I felt that half the orchestra had decided to go home. A call to The Cartridge Man confirmed my thoughts as he said exactly the same. Great minds think alike maybe?

So where does that leave you? You have the chance of listening to a revelation in record reproduction but you can't because of the hum. Well, that's because high gain equipment, which phono stages are, will be influenced by the surrounding hum field. The stage itself doesn't produce hum. Not mine, not his, not transistors, resistors or capacitors.

Transformers produce hum, wiring with mains power in it produces hum, unscreened valve amps produce hum (modern valve amps are usually supplied without a cover these days to look trendy and macho - the cover that used to be fitted in the pre-macho-image age afforded some screening).

The modern practice of showing off equipment on "the hi-fi rack" is not conducive to good vinyl replay. I'm sure you know (or can imagine) what an earth tremor feels like at the top of a skyscraper? You put the big amp on a lower shelf. It contains a transformer. Ever picked up a working transformer? It vibrates at 50/60Hz and you can feel it (yes, even a torroid). The hi-fi rack vibrates at 50/60Hz and by the time these vibrations reach the turntable placed on the top shelf, it's been amplified by the structure - and the cartridge vibrates - and the cartridge produces an output - and the phono stage amplifies it - unless that is, it has a notch filter.

 

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Graham Slee - General FAQ

 

Will I need 2 interconnects when I use or upgrade to the Elevator Basic, Basic Plus, or EXP ?

"The Elevator has a very low driving impedance making it remarkably tolerant of capacitive loading effects of different interconnects. Provided a decent one is used (not the cheap "figure of eight" variety) performance will not be dictated by the interconnect. Furthermore, the phono sockets used are of the highest standard gold plated/Teflon insulated and therefore the quality gains of the two products will outweigh the perceived minute losses by several orders of magnitude."

 

In any case, we now have a suitable cable with low capacitance and superior shielding, at a very affordable price considering that it is terminated with Cardas RCA connectors, one of the best.

 

How does one make the connections if used with an Elevator ?

The tonearm cables go into the input jacks of the Elevator.  An interconnect cable is then used from the output jacks of the Elevator into the input jacks of the Era Gold / Jazz Club / Gram Amp 2 SE or your MM phono stage.  Another interconnect is used from the Era Gold / Jazz Club / Gram Amp 2 SE MM phono stages into the preamp.  Of course, there is no interconnect needed if your MM phono stage is built in into the preamplifier.

 

I noticed that the Elevator has switches for resistive loading, what is resistive loading ?

Resistance (in ohms) - Here's an excellent explanation which we found at the Vinyl Asylum:

"Each cartridge has a recommended resistance load, measured in ohms (W).  With cartridges, as in most things audio, how you load is based upon what you like the sound of; I personally do not know how loading will affect your cartridge electrically, but the reason that one loads down (that is, reduces the resistance) on a moving coil cartridge is generally to reduce resonances in the electrical system and to increase the power transfer from the generator( the coil) to the pre-amp. The effect of loading is apparent at frequencies that the electrical circuit of the cartridge resonates at. Moving coils often have a rising top end, and a resonance at frequencies above human hearing; but, such frequencies can get into the audible range through modulation distortions (which simply means that frequencies are shifted from one range to another). If the system is under-damped and resonances are great you will notice some fatigue in listening and a grainy quality in the higher frequencies. If a moving coil sounds slow or languorous, then it may be over-damped.

Start with the manufacturer's recommended settings (or as close as possible), and let not the opinions of others rule your preferences, play with the loading and leave it where you like the sound as it is you who listens to the music."

 
Why do we need 2 boxes to play low-output MC cartridges ? 

Well, it can sound better, basically, with the elimination of unnecessary switches.  Graham Slee belongs to the camp where an extra cable to connect the boxes is still a much better solution compared to having switches.  This results in optimum performance from either type of cartridge - MM or MC.  Each box have their own separate superior power supply.

 

"Moving coil phonograph cartridges usually have very low outputs. Some manufacturers make phono stages that can be used for both the high output type of phono cartridges (moving magnet type and some high output moving coils), as well as the usual low output moving coils. A simple switch selects between high gain for moving coil, and normal gain for moving magnet. This arrangement has major drawbacks in maintaining the accuracy of frequency equalisation between the two settings. Very often the moving coil is favoured - the preamp is made to be accurate in moving coil mode, and therefore inaccurate in moving magnet mode. This has led to a decline in the popularity of the more affordable moving magnet cartridge and bolsters up the image that hi-fi is expensive - that you must spend silly money for the best sound. You don't have to and we are dispelling that myth. By separating the functions of moving magnet and moving coil into individual specialised circuits, both cartridge types are allowed to compete in equality.

The Elevator EXP head amplifier serves the purpose of amplifying the low output moving coil signal to the equivalent of moving magnet. Then either that signal can be applied to the input of our conventional moving magnet stages, or, indeed, a moving magnet can be played directly such that the optimum performance can be obtained from either type of cartridge. This (forgotten) technique was noticed by Hi-Fi News magazine, who's panel auditioned the EXP/Era Gold phono stage combo, and gave it their award for best phono stage 2004."

 

Read More ...
 
Isn't it inflexible compared to others with MM/MC switches ?

Flexibility in phono stages can take its toll on the sound.  Too many switches/controls can spoil the broth, as explained above in FAQ No. 4.  All we can say is - you might "switch" to the lesser-switch Graham Slees  :-)  Of course, that's just us ... you may have other sonic priorities or prefer flexibility over sound quality.

 

The Gram Amp 2 SE is only MM.  Can I upgrade using the Elevator to play low to medium output MCs ?

Yes, we sometimes run out of Era Golds and have to use the Gram Amp 2 SE in our demo room with the Elevator EXP, and it is superb.  Furthermore, the SE was developed for high quality MMs and the performance/cost ratio is far better than using a budget MC with a universal phono stage. There is no way a cheap universal stage will outperform the Gram Amp 2 SE with an MM (see Stereophile June 2002)

 

Does the Solo have an on/off switch ?

The Solo has a mute position on its input selector toggle switch (between input 1 and input 2, centre "off"). Using it you can leave the headphones connected and the volume control set to your favourite position, when listening with your speakers. It is designed for the power NOT to be switched off, just like the other products - the longer it's on, the better it sounds.

 

What are the recommended headphones to be used with the Solo ?

The Sennheiser HD600 and HD650 sounds great from the Solo, but also the HD250 II (closed back) is pretty fantastic. Some say the 250 II isn't that good, but I doubt they've run them in for long enough (mine have taken 3 months!), or driven them with a Solo. Quite a lot of commercial music was monitored using the HD 250 MK I over the years, they reintroduced it (as MkII) because of professional demand ...!

 

Also, the Solo is still the choice of Sennheiser UK for its ability to drive the HD600/650 headphones really well - take a listen with the Solo Monitor Class at any of the major UK Hi-Fi shows.

Of course, your favorite brand/models should work well as well.  It works very well even with the low-cost Grado SR60.

 

Furthermore, "because of the current drive there is not the usual massive and awkward to control difference in volume level between headphones of different impedance's. It's output to 300 Ohm Sennheiser's and 32 Ohm Grado's will be broadly similar."

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Graham Slee FAQ : Frequently Asked Questions

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