Monday, March 30, 2009

A visit with the Graham Slee Era Gold Mk V phono preamplifier

The rather unassuming looking Graham Slee Era Gold Mk V (now that is a mouthful) phono preamplifier is an IC based unit that goes for the rather princely sum of $999. Now that is really a pittance in audiophile money, but when you open the shipping box you expect something larger for something just shy of $1K. In my poverty-filled college days I've driven cars that cost less than this little box! Of course what you are paying for here is a hand-built and thoroughly tested unit. This is a level of quality control that many companies would never do.

Era Gold Mk V is meant to be used with MM or high output MC cartridges since it has no switchable gain. Gain is set at a fixed 41.5dB and with no power switch it is also meant to be left powered on at all times. There is only one set of stereo RCA inputs, a grounding lug, a DC input and of course a set of stereo RCA outputs. The power comes from an outboard PSU1 regulator and further regulation also occurs within the phono unit itself.

I bought the
Era Gold Mk V used via Audiogon to partner up with my newly bought VPI HW19 Mark III turntable and Ortofon 2M Blue cartridge. I have to admit I wasn't expecting much from the Slee - having pretty much resigned myself to using tubes in this crucial part of the signal chain. I'm no fan of ICs and thought this unit would just end up being a temporary stop before I bought a more expensive phono stage. To my ears op-amp based circuits normally sound hard and grainy and I've never heard a circuit using them that ended up sounding good.

So how does this little beast sound? In a few words, very neutral. Bass is shockingly deep compared to several of my previous tube preamplifiers. It also does not have any of the round euphonic bass I associate with tube gear - instead bass is taut with excellent definition. The treble is very controlled and non-spitty sounding. However the very last bit of air and sparkle seems to be missing compared to some of the better units I've heard. This is a minor quibble but still worth noting. The most important part - the midrange - seems to be extremely neutral without any major colorations or immediate problems. In comparison tube units have a bit more 'bloom' and 'color' but can also suffer from decreased resolution and transparency. With the Slee, detail is very good without being overdone. At no time does the recording ever sound zippy or forward unless it was mixed that way.

In conclusion the
Graham Slee Era Gold Mk V is a good partner with my Threshold gear. With my UREI loudspeakers I am given a full range, neutral and transparent sound. Even if I purchase another phono unit, the Slee will stay in the stables to provide a reference for future upgrades.


Monday, March 9, 2009

A visit with the VPI HW-19 Mk III

I first heard the VPI HW-19 turntable way back in my early audiophiles day of 1990. It was a friend's setup using Quad ESL-63 speakers, a heavily modified and fully regulated McIntosh 240 amplifier and a regulated Dynaco PAS. The VPI sported an air bearing Eminent Technology ET2 tonearm and a Sumiko Bluepoint. Up to that point my experiences with turntables was limited to my father's Garrard unit and the various 'mainstream' Japanese turntables that were popular at the time. So needless to say I was surprised how good records could sound. I never heard hall reverberation, vocal and instrument realism like that before. You have to remember that this was the heyday of CDs and everyone was ditching their vinyl collection so it seemed at odds against the stated supposed superiority of digital. Well VPI certainly changed my mind about digital and due to my college budget I ended up buying a used Thorens TD-165 table. I never got the great sound out of the Thorens that I heard on the VPI and at the time I attributed the differences to cartridges, preamps and my cheaper speakers. Back then I made the mistake thinking that the amplifier made the biggest difference in the signal chain.

As the years went by and CD sales grew larger and larger, I ended up slowly decreasing my record collection purchases. With CDs I could copy and rip down songs - plus my interest in new releases and re-issues limited my purchase of records. After my experiences with the Monica NOS and the transformer coupled RAKK DAC I began to think that digital has finally been able to sound good enough to compete with a good turntable setup. And why bother with the fussiness of analog? Record cleaning, cartridge changing and 'table setup has certainly driven away the masses and me along with them.

I recently hooked my UREI 813A loudspeakers back up to do some amplifier testing. I've always liked the overall UREI sound but was disappointed in the higher frequency dryness - attributing any nastiness to the horn loaded compression tweeter. I was thinking of buying some Magnepan loudspeakers and continuing on my digital path until my fellow 'phile friend let me borrow his second vinyl rig. This is his setup that he uses for needledropping and consists of a glass platter Rega P2, Ortofon 2M Red and a simple phono stage that I built for him some 2 years ago. It is basically an ARC SP-3 type 12AX7 based circuit but with a much beefier choke based power supply.

I honestly wasn't expecting much from this setup when we hooked everything up. And I knew there was going to be some bass rolloff problems with the high impedance phono driving the 25k input load of the Threshold FET-10/HL linestage. So we queued up our first record - "Buddy Guy & Junior Wells - Drinkin' TNT 'n' Smokin' Dynamite" - and sat back to listen. Wow! I was taken aback by the smoothness and overall coherent sound of this setup. Sure, there were minor issues - but the musicality beat out my more expensive RAKK DAC on several levels. And oddly enough the irritating drynesss of the treble was gone!

After listening to a few more records I came to the conclusion that all along that the UREI 813As were telling me that many DACs have difficulties reproducing high frequencies. So I was blaming the speakers when instead they were just telling me the truth all along. Soundstaging, detail and body was better too. There was just something 'right' about the sound that made me enjoy music on a more emotional level. Looking back it seems that the RAKK really made me look at music objectively instead of enjoying the beauty and art.

So with that in mind I decided against buying the Magnepans and went for an analog upgrade instead. My vinyl-friend recommended a VPI - he is familiar with them since he runs a MKIV with the TNT platter upgrade and a SME 309 tonearm. So I cruised through Audiogon until I found a MKIII that looked good. This one sports a Rega RB300 and has been modified to have VTA on the fly. I also bought an Ortofon 2M blue and a Graham Slee Era Gold Mk V to round out the signal chain.

The older HW19 turntable are fairly unique for their floating plinth. The plinth supports the heavy platter and arm, but sits on top of four springs. This is meant to isolate the table from the motor. Many more modern designs seemed to have shied away from this approach - using a single heavy plinth to support everything. Though this reduces the construction cost, I would think that unless great care is taken there will still be more motor vibration issues.

How does the VPI sound compared to the Rega P2? Well I'm running a slightly different cartridge - but there seems to be more solidity and more of a foundation to the music. There is more inner detail and the overall sound is cleaner too. In comparison the Rega sounds a little gray and 'dirty' in the background. This is an effect of the less weighty platter and cheaper overall construction. However the Rega is still a good table and worth the trouble for a beginning setup.

I still have some cartride break in and VTA tweaking to do - so I'll report on the Ortofon 2M Blue and Graham Slee on a later posting. But for now I'm pleased with my purchase of the VPI - it has been a big upgrade to my enjoyment of music. I can't wait to start the upgrade process with better cartridges, a VPI SDS power supply, SAMA, tonearm upgrades, etc. This is certainly a fine way to drain my already economically damaged bank account!


Wednesday, March 4, 2009

Amplifier Update - an 'Universal' Single Ended amplifier

I have sold my Single Ended EL156 monoblock amplifiers to a friend of mine. However he has a number of output tubes that he would prefer to use over the EL156. With that in mind we made some changes to his amplifiers so he could safely run the 6550/KT88/EL34/6L6GC/etc.

The self bias adjustment resistor was changed to a 500 ohm / 5W potentiometer. This allows a large range of bias, allowing the use of several different types of output tubes. I also knocked down the B+ so tubes with a smaller plate dissipation than the EL156 could be used with a bigger margin of safety. Note that I used a 200mA meter to measure the amount of current flowing through the output tube - a 100mA meter would also be suitable for most tube types.

The original 1.5uF power supply capacitor was changed to a .68uF unit. The 82k EF86 dropping resistor should also be changed to 50k.

These minor changes have allowed the amplifier to be used with a wide variety of output tubes. Power output has dropped versus the EL156, but with the right speakers and listening space this amplifier continues to shine. With a pair of original Tungsol 6550s we listened to a few songs on a pair of KEF C-75 speakers and this amplifier sounds very fast with a delicate sweet treble. I'm in love with the sound of this amplifier all over again!

One could also roll EL38s (with plate caps), 6AR6s (with wiring changes), TT21s (with plate caps), and a whole bevy of other output tubes. Have at it.