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A really great turntable deserves a really high quality phono pre-amplifier and the ESP Hi-Fi RIAA Hi-Fi Phono Preamp has been very highly recommended to me by our contributor Felix Scerri. Apparently many other vinyl enthusiasts also enjoy extremely good results with the ESP P06 phono pre-amplifier.

I decided to not only build the ESP P06 RIAA Pre-amplifier but also the P99 Subsonic (Rumble) Filter and house them together in a neat case. The subsonic filter is useful in that it filters out all the low frequency noise that is caused by record warps, rumble cut into the record at the cutting stage and any rumble that may be present on the playback turntable itself. It is extremely wise to filter out all that low frequency 'junk' as it wastes a lot of amplifier power unnecessarily, which can otherwise be used for the reproduction of real music.

The ESP Project 06 preamp is designed by Rod Elliott who designs many very clever, and useful electronic circuits. This particular project and some interesting design notes can be found on Rod's website, Elliott Sound Products, at http://sound.westhost.com  Felix Scerri comments: "Rod Elliott's site is excellent!  Rod is a genius, and his whole site is amazing......"

Rod Elliott's design is a very interesting one, as will be seen by reading his web pages, and he makes available high quality PCB's for many of the designs.

This is a fascinating DIY project for those who have some experience with and enjoy building electronic devices and are able to solder neatly and effectively. What will result is an very high quality hi-fi phono pre-amplifier that will produce extremely good sound quality.

Above: Soldering components into the P99 subsonic filter circuit board

A phono pre-amplifier is required for two reasons;
1) The electrical output from a pick-up cartridge is too tiny to be loud enough if connected directly to an ordinary stereo amplifier 'line-in' input;
2) When a record is 'cut' the amount of treble sounds are boosted by an exact specified amount (+20dB at 20kHz), while the amount of bass sounds are reduced by an exact specified amount (-20dB at 20Hz) using a special electronic equalisation curve standardised by the RIAA (Recording Industry Association of America) - so when the record is played back on your turntable the exact opposite of this filter curve is used: The RIAA equalisation in the phono pre-amp will boost the bass frequencies (+20dB at 20Hz) and cut the treble frequencies (-20dB at 20kHz). This improves reproduction of two counts; The reduction in treble energy helps reduce surface noise while the reduction is bass output is necessary because bass frequencies modulate the record groove to a great extent (lots of vibration). Without equalisation the cutter and the pick-up stylus would find it difficult to function properly due to the great amounts of stress created and cause mis-tracking and distortion during playback.

Rod has very carefully designed his pre-amp's circuitry to follow the RIAA equalisation curve, except that he decided not to fully employ the usual flattening of the RIAA curve below 50 Hertz. This gives a slight bass lift which many listeners found to be more natural and preferable compared to the standard curve. This slight bass lift and the fact that the -3dB point of this amplifier is all the way down at 3 Hertz could potentially be problematical on three counts:

1) Unless using a very high quality turntable with very low rumble, such as the Technics SL-1200 MKII, low frequency noise could be a problem.
2) Unless using a turntable that is very resistant to acoustic feedback, such as the Technics SL-1200 MKII, feedback should be considered.
3) Many, if not most, records are in fact 'cut' with a certain amount of cutting rumble - low frequency noise.

Rod Elliott comments that low frequency noise has not presented a problem, but does offer some tips to help eliminate feedback on his pages.

Because of the excellent low frequency response of this preamp circuit and the fact that this could emphasise 'cutting rumble'- the low frequency noise recorded into the record's grooves - I decided to incorporate Rod's own Sub-Sonic Rumble Filter (Project 99) into my own preamp. Rod's P99 Sub Sonic Filter circuit steeply cuts off low frequencies below 20 Hertz thereby minimising low frequency noise.

These two circuits need a +/- 15 Volt regulated power supply and Rod Elliott's ESP website also features an extremely high quality, low noise power supply circuit designed for the job. See Project 05B.

I would recommend buying the PCB's (circuit boards) directly from Rod's site for three important reasons:

1) His PCB's are of extremely good quality and it will save a great deal of time' mapping out' the schematic circuit diagram over to a piece of strip-board;
2) Rod puts an enormous amount of effort into his website and it is only reasonable to support his efforts by buying his products - without such sales his invaluable website would close down;
3) When you buy the PCB's from ESP Rod will also provide you with lots of additional information about the circuit designs which does not appear on the general website - this consists of additional components and circuit details that are required to refine the circuits, plus plenty of useful constructional and testing tips.

ESP's High Quality Project 06 Hi-Fi Phono Pre-amplifier designed by Rod Elliott
Visit: http://sound.westhost.com/project06.htm

TIP: Wait until you receive the PCB's from ESP before you buy your electronic components, since the PCB's are provided with comprehensive instructions that will also detail additional components that are not mentioned on the above pages. This will save an unnecessary journey to the shops or unnecessary additional postage costs when buying via mail order or the internet.

The components used in the project(s) should be of good quality but some of the values can be a little tricky to find. However I have found that everything necessary can be purchased from two suppliers; Cricklewood Electronics and Jaycar Electronics. Although Maplin in the UK certainly do stock some of the necessary components they fall short in a few areas.

There are twelve identical capacitors used in the P99 subsonic filter circuit. The value specified is 150nF which gives a -3dB roll-off point of 17Hz, however I chose a value of 120nF which gives a -3dB point of 22Hz. This is personal choice and all is explained in Rod's instructions when you buy the PCB from him. These capacitors can be MKT types which are available from Jaycar with 10% tolerance, or the polyester film boxed capacitors which are available from Cricklewood Electronics (part number CPB150N). I obtained my 120nF MKT box capacitors from Jaycar Electronics. I found that Cricklewood supply 150nF box capacitors which are advertised as 10% types, but the actual capacitors supplied in this instance were 5%, which was a bonus. I used these for the construction of my second ESP P06 and P99 Preamp/Subsonic filter.

For the most accurate results, as mentioned above, it is desirable to measure each resistor and capacitor before inserting into the PCB. The most important aspect to consider is Left and Right channel matching, so wherever possible ensure that the value of each component on the left hand channel matches, as closely as possible, its counterpart on the right hand channel.

Semiconductors: All the semiconductors should be widely available. I purchased the four NE5532P dual op-amps, used in the P06 preamp and P99 filter, from Maplin Electronics.

Felix Scerri notes that the LM833's are equivalent to the NE5532 and work well in this application.

I.C Sockets: Some extremely sensible advice from Felix Scerri is to use IC sockets for the op-amps rather than hard soldering them into the board.

I obtained the IN4003 diodes for the power supply from Cricklewood Electronics, who also supplied the 7815 (+15 volt) and the 7915 (-15 volt) voltage regulators for the P05A power supply. Bear in mind that the current power supply board now supplied by ESP is the P05B which uses different (adjustable) regulators - the LM317 and LM337.

Hardware:I found a really excellent instrument case from Jaycar Electronics. It is supplied with feet and all necessary screws, measuring 150mm x 61mm x 102mm (L x H x W) (Jaycar part number: HB5442 *see note below). 3mm x 25mm nylon screws (10) and 3mm nylon nuts (30), both available from Jaycar Electronics. The RCA phono sockets are gold plated and were from Cricklewood Electronics - 2 red and 2 black (part numbers PCGR and PCGB). The 3mm LED and translucent plastic mounting clip, the ground terminal post, the 2.1mm power socket and the rubber grommet that it is mounted in were all obtained from Maplin Electronics. If you decide to use I.C. sockets for the NE5532 I.C's, 8 pin DIL sockets are available from Maplin Electronics. You'll also need some screened audio cable and some different coloured hook-up wire. A small piece of aluminium with which to make the internal shield, you may have a suitable piece of scrap aluminium, otherwise suitably small pieces of often available on Ebay.

* Note about case. You will notice that the power supply circuit board that I used is different to the one supplied by ESP - I used my own for this project, though I would recommend obtaining the 'real thing' from ESP for ease of construction (PCB P05b). However my board has different dimensions to the ESP board; the ESP bord is 46mm wide, whereas mine is only 40mm wide, so this may have implications when fitting it into the case. I think the ESP board would just about fit into the space on the HB5442 case, but if not there are two alternatives: a) buy the slightly larger, but identically styled case from Jaycar or b) mount the PCB vertically on the vertical face of the internal shield - ensuring that the aluminium is thick enough to be able to firmly support the PCB.

If it is not possible to order the case and nylon screws from Jaycar Electronics, I have found alternative products. Please check the dimensions of each box before making a decision to ensure that it will be the correct size for your particular project:

The AB13 or AB31 aluminium boxes from Maplin Electronics may be suitable. They are basic but will do the job. Visit Maplin Electronics: http://www.maplin.co.uk

The  30-0230 or 30-0235 metal cases from Rapid Electronics are much nicer looking than the Maplin boxes, but note that the longest side is the front panel. This should not be a problem, it just depends how you wish the completed pre-amp to look. Visit Rapid Electronics: http://www.rapidonline.com

BOX-JS6 or BOX-JS8 aluminium boxes from JAB Electronics also look as if they may be ideal for this project. Visit the JAB Electronics website : http://www.jabdog.com

Nylon M3 cheese head screws and nuts are also available from Rapid Electronics. Visit the Rapid Electronics website:  http://www.rapidonline.com

Nylon M3 screws and nuts are also available from modelfixings.co.uk Visit:  http://www.modelfixings.co.uk

Other: An AC plug-top power transformer supplying a voltage of between 16 and 20 volts at 500mA or 1000mA is the required power source. This must supply AC and not DC. I found a suitable plug-top AC to AC adaptor from Maplin Electronics which is adjustable from 3V to 15V AC. The part number for their 500mA AC/AC power supply is N57AT . Maplin also supply a 1000mA version with part number N58AT. Visit Maplin Electronics at: http://www.maplin.co.uk Alternatively high quality plug top AC to AC power supplies can be purchased from Remtrak. The part number for the Remtrak 18 Volt AC 500 mA power supply is PSC00164, visit Remtrak at: http://www.remtrak.com/psu/psu.htm

Tools: 30 or 40 watt fine tipped soldering iron and stand. Solder. Small flat head and Philips head screwdrivers. Digital multimeter, preferably with capacitance meter, such as the excellent value QM1324 DMM from Jaycar Electronics. Wire strippers. Small side cutters. Small pointed nose pliers. Small I.C. tweezers would be helpful. "Helping Hands" to grip PCB's while soldering (see photograph above). Electric drill and various size drill bits. Tin snips or strong scissors. Round file. Ruler or tape measure. Fine tipped marker pen or pencil. Piece of scrap wood to drill into and cut objects on.

Once all the electronic components and other parts have been gathered together it will be time to start assembling the PCB's. I won't enter into all the details here as the instructions provided with each PCB bought from ESP will provide all the detail needed to build each board plus the testing procedure required before finally connecting everything together. Some of the tracks are quite small and close together, so a fine tipped soldering iron is essential to ensure that soldering is as neat as possible. There is one wire link that needs to be soldered to the underside of the P99 subsonic filter PCB, and this is quite fiddly and needs thin wire, a steady hand and a fine soldering iron tip.

Wiring Up:

I used various colours to signify different things; e.g. I used some ribbon cable for the power connections with brown for ground/earth, red for +ve supply and black for -ve supply connections. Green of brown could be used for other ground/earth connections.

Once each PCB has been assembled and tested according to the instructions provided by ESP, the boards will need to be connected together. Plan the orientation and positions of the boards within the case before wiring up to keep the wiring as short as possible, this will not only aid neatness, but also prevent any hum or noise occurring.

The +15v / -15v power supply  needs three wires for connection to the pre-amp and subsonic filter boards and it is absolutely essential that these three wires go to the correct positions on each board. +ve must go to +ve, -ve must go to -ve and don't forget the ground wire.

The input end of the pre-amp PCB should be to the rear of the case so as to be as close as possible to the RCA Phono sockets that accept the input from the turntable, this will keep the wires as short as possible, taking care to connect the red (right hand) socket to the right hand input terminal. The subsonic filter PCB is positioned close to the pre-amp circuit with the input end next to the output end of the pre-amp, this, again, keeps the wires as short as possible as each output of the pre-amp is then connected to each input of the subsonic filter. The final connections are from the output terminals of the subsonic filter to the output sockets on the rear of the case. Take care to check that the Right hand channel and the left hand channel follow through the circuits correctly and do not get transposed.


Power connector:  I found that I needed to isolate the 2.1 mm power socket from the case, so for this I drilled a hole that would accept a small rubber grommet with a hole that was a very tight fit for the power socket. The socket was then firmly pushed and twisted into the grommet. It seems very secure and it's not as if the power plug will be continually pushed in and pulled out.

For the instrument case I measured out where all the sockets and boards would be best placed by drawing out the layout on a piece of paper and rearranging it until everything fitted neatly without any one item fowling another. I placed the PSU board at the front of the case and the pre-amp and subsonic filter boards to the rear so that they were close to the input and output sockets.

I had also decided to fit a screen to shield the sensitive high gain amplification used in the audio circuits from the power supply circuits, so I made up a card template for the screen initially to find the best shape which would then be transferred to the metal sheet marking where it needed to be cut and folded. A hole was also drilled in an appropriate place on the shield and a small rubber grommet fitted in order to allow the ground, positive and negative power supply wires through from the PSU compartment into the audio circuitry compartment.

Once the metal shield was made, it could then be used, along with the other drawings and measurements to mark the positions of all the holes that needed to be drilled in the case. Before doing any marking or drilling the metal surfaces were first protected from damage by sticking masking tape over them. Once covered in tape the case could be marked up and drilled and then filed with little risk of scratching or marking the delicate surfaces.

When all the forming work was completed the masking tape was removed the sockets could be fitted, the 3mm plastic LED holder pushed into place and the metal screen secured into place by using some short 3mm plated machine screws and nuts.

The PCB's were fixed into place within the case by using some 3mm by 25mm long nylon machine screws. You'll need ten nylon screws and thirty 3mm nylon nuts. The nylon screws are pushed through each PCB mounting hole from the bottom of the case and tightened into place with one nut. A second nut is threaded down the screw until the top surface of the nut is about 8mm from the bottom of the case - or a least at the minimum height that will allow a few millimetres of clearance from the bottom of the case to the underside of the PCB so that there is no possibility of a short circuit. Once the PCB's have been fitted over the mounting screws a third nut is used to make the mounting secure. This should be clear in some of the photographs below.

SHORT REVIEW SO...WHAT DOES IT SOUND LIKE? Suffice to say that the ESP pre-amp is very good indeed and out of the four phono pre-amps that I now have, this is easily the best. Comparisons: Previously I had tried the Audio Technica AT120ET on a Yamaha stereo amplifier with the built-in RIAA pre-amp and found that this combination was rather too bright. It was certainly fast, pacey and detailed, but it did not sound completely natural to me. I then switched to a Marantz stereo amplifier with its internal RIAA preamp and found that the results were very good indeed. There is plenty of detail with this combination, though there is a tendency for some reticence in the bass and some slight emphasis in the treble which makes for a sound balance which is slightly on the lean side though, it must be stressed, still very musical and enjoyable, fast and agile. The overall result is very musical and always passes my 'foot tapping' test. I also compared the Marantz internal RIAA pre-amp with a Pro-ject Phono Box. The Pro-ject is a quiet external pre-amp and worked very well. I again found the sound to be very enjoyable and agile but once again this combination did emphasise a slight brightness in the AT120ET cartridge and I fancied that there was just a tiny little less bass depth - though that was rather difficult to pin down to a real lack of bass depth or simply as a psychological consequence of the amp being a little brighter than the Marantz preamp. On balance I felt that the Marantz pre-amp gave the better balance with the AT120ET, although I would say that the Project might be the more capable pre-amp given a different cartridge. I usually use the Pro-ject Phono Box on a different system with a Rotel RP-855 turntable fitted with an Audio Technica AT110E cartridge. In this particular system combination I find that the Pro-ject box works very well with the AT110E cartridge, the sound has good depth and quite good levels of detail and does not have a tendency toward brightness. However although the AT110E is a fun cartridge and seems a little more fulsome in this system it does not have the engaging finesse of the AT120ET. Of course I am comparing two entirely different systems here and, indeed, I have not done an intensive side by side comparison which is a little unfair since the Technics Sl-1200 MKII is also a much more capable turntable. The ESP P06 So to the ESP Preamp: The first system I tried it in was the Rotel RP-855 and AT110E combination. In this system the brilliantly fun and energetic AT110 cartridge has a slight tendency to brashness and this appeared to be tempered by the ESP preamp, not only that, though, but the ambient details were enhanced giving recordings more presence and space. Moving the ESP preamp to the main system and its intended home revealed the ESP pre-amp to be a star performer. Compared to the phono preamp built into the Marantz amplifier the overall signature of the Audio Technica AT120ET cartridge was still present - sweet, detailed and musical - but there was just more of everything. The music gained weight and scale, there was also bags more ambience and presence and music had even more focus. The AT120ET's very slight tendency towards brightness was also expertly tamed by the ESP pre-amplifier, though the tremendous levels of detail remained. I have to say that this new phono pre-amp really allows the Technics SL-1200 and Audio Technica AT120 combo to breath and really sing. The marvellous quality of the ESP Phono Pre-amp was no better demonstrated than with the reproduction of the 1973 LP Dark Side Of The Moon by Pink Floyd. This LP is a firm favourite and on the amazing Technics SL-1200 / AT120ET combination is startlingly good. When the internal Marantz phono pre-amp was replaced with the ESP pre-amp the effect was even more wholesome. The improvement is bass depth and extension was immediately apparent, but the the sound-staging, atmosphere and presence was phenomenal. The great strength of the ESP preamp is depth and ambience, and I feel that it could bring such improvements to any system. The fact that it also tames the AT120ET's tendency for slight brightness whilst retaining the incisive detail and complete musical enjoyment is a huge bonus. N.B. Brightness, i.e. treble emphasis, can be caused by incorrect capacitance loading of the pick-up cartridge by the phono pre-amp. This is discussed on a previous page here. More below...   The completed ESP project: High Quality Hi-Fi RIAA Phono Preamp with Rumble Filter Observations From Felix Scerri: G'day Mike, a very nice and highly readable page for the P06 and P99 phono stage combination.  One reason why I think the P06 sounds so good is because of the way the equalisation is implemented with part active (for the bass end), and a simple passive roll off filter (for the treble end).  I actually regard the high frequency performance of the P06 as its best feature, although it is a superb preamp in all respects. I'm glad to know that there is a nice synergy with your A/T cartridge, and it does indeed sound like the slightly enhanced bass end of the P06 works out well with your A/T cartridge.  I suspect that the same sort of thing happens with my Ortofon Super OM 30.  It is interesting to note that with the P06, as the treble roll off is provided by a simple filter to earth, this actually provides the 'ongoing' 6 db/octave roll off as is required by the RIAA 'spec'.  Most op amp based phono preamps, unless they are using full passive equalisation which can be problematical circuit wise for a couple of reasons, tend to use straight 'feedback' equalisation in the normally used 'non inverting' op amp circuit, and this circuit does not provide 'ongoing' roll off, as in that configuration, the gain eventually actually drops to unity (1) at some frequency, and no lower.  Although the non inverting op amp circuit appears to give satisfactory adherence to the RIAA curve, and is actually very widely used in most simple (and cheap) phono preamps, in reality it doesn't, whereas Rod Elliott's P06 phono preamp does, due to the use of a passive roll off filter, and the HF roll off is essentially ongoing due to the filter action. Regardless of circuit reasons, the P06 is a great preamp.  I have built a number of different phono stages over the years (mainly full 'feedback' designs), and after building several P06's for different applications, I have absolutely no desire to use or try anything else, although I did think about a modification a while back that made no improvement at all, and possibly just degraded things slightly! One thing that never ceases to amaze me, is the cost of commercially made phono stages versus the all up cost of a superb DIY  phono stage like the ESP P06 design.  Whenever possible, I'd rather 'home brew' (make it myself), and the quality can be quite superior, as with the P06.  Enjoy that P06/ P99 combination Mike.  Regards, Felix Scerri. Any Comments?  We'd love to hear from you! Do get in touch HERE >> .

LINKS

If you fancy building the P06 phono preamp here are all the links that you'll need:

ESP (Elliott Sound Products) RIAA Preamp:  http://sound.westhost.com/project06.htm
ESP SubSonic Filter: http://sound.westhost.com/project99.htm
ESP  +/- 15V Power Supply: http://sound.westhost.com/project05b.htm
Cricklewood Electronics: http://www.cricklewoodelectronics.com
Jaycar Electronics: http://www.jaycarelectronics.co.uk
Maplin Electronics: http://maplin.co.uk
Rapid Electronics: http://www.rapidonline.com
JAB Electronics: http://www.jabdog.com/
Henrys Electronics: http://www.henrys.co.uk
Model Fixings: http://www.modelfixings.co.uk
Bowood Electronics: http://www.bowood-electronics.co.uk/
http://www.thesimpsons.com

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FAULT FINDING & PROBLEM TRACING TIPS: Having problems? Here are some things to think about and things to check.... If the op-amps and electrolytic capacitors don't go up in smoke then they are most probably orientated correctly. Therefore it probably goes without saying (although I will) that if they do go up in smoke then either they were inserted with the incorrect orientation, or the power supply wires were reversed. Always double check that the power supply wire are not reversed before applying power - otherwise it will be too late! Some extremely sensible advice from Felix Scerri is to use I.C. sockets for the op-amps rather than hard soldering them into the board. Check for solder splashes and bridged tracks on the PCB and mis-placed or incorrectly connected wires. Ensure all the components have been placed in the correct position in the circuit board. Double check component markings and part numbers. Double check component values, such as resistors and capacitors with a multimeter. Check for continuity of wires and PCB tracks with a multimeter or continuity tester. A 'wet' finger on the phono preamp input will prove the stage is amplifying by producing a loud 'buzz'.  Of course you need to have the output of the phono preamp powered up and plugged into an amplifier for this test, and also make sure you haven't reversed input and output leads and /or plugs. Ensure that ground wires go to ground connections and that connections carrying the signal go to the correct place and not to ground. Check that all known voltages appear on the right places on the board, and especially check for circuit continuity between all the input and output sockets and terminals on the board by using a multimeter. Check for a lack of a proper earth return for the power supply lines. It is easy to make mistakes especially if one is keen to get something finished and operational. It's always wise to have a cup of tea and a break, and maybe even sleep on it and then go back to the project later. Hum or Buzz? If it's a noticeable buzz then ensure that the turntable 'earth' wire to the preamp chassis / earth, omitting that will certainly cause a buzz. Check for the possibility of transposed or reversed connection on the inputs or outputs, because the pins are quite close together on the ESP  boards and it is easy to make a mistake. If there is a loud hum then check power supply earth/s and also that the 16 volt AC supply is not grounded at the input socket or at any point before the PSU circuit board. The power supply in this circuit should only find its grounding point from its connections to the RIAA pre-amp and/or subsonic filter circuits via the three wire power connection - i.e. the +15volt wire, the -15volt wire and the ground wire (The Red, Black and Brown wires shown in my photographs above). If it is found necessary to remove a component this can be done with the correct de-soldering method. De-soldering is fiddly but if done carefully the board should survive but you may find some tracks 'lifting'.  Removing components from a PCB requires very careful and accurate de-soldering and the use of a special 'De-Soldering Pump' (available from Maplin) and maybe some De-Soldering 'Braid' as well which can also be useful. Thanks to Felix Scerri VK4FUQ Also see the Resistor Colour Codes, Capacitor Conversion Table and LED Information page HERE>> .

OH, DON'T FORGET! .

The KAB EV-1 Record Cleaning Machine
http://www.kabusa.com

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