RIAA/Phono preamplifiers & moving coil transformers

Separate phonographic pre-amplifiers, also known as RIAA preamps and compensation amplifiers, are devices that allow you to on one hand to connect a turntable to a device that has a line input but no turntable input, such as a music system, a computer or an amplifier, or on the other hand to upgrade a device such as an amplifier that actually does contain a turntable (phono) input but either of a low quality or of not sufficient flexibility to allow you to use the pickups that you want to use with your set-up.

Note that most budget pre-amps and even some of the more upmarket models as well only have a limited gain and impedance flexibility making them only suitable for use with moving magnet or moving iron cartridges. While most pickups that are shipped as standard with record players are indeed moving magnet types, most mid end and all high end pick-ups are moving coil devices. If you want to use one of those in your system you can either do a bit of research beforehand and choose a pre-amplifier that mates with both MM and MC pick-ups, or alternatively get a Moving coil preamplifiers when you purchase a MC cartridge, but those are transformers or electronic devices that amplify a signal from a moving coil pickup to a level where it can be used with normal phono inputs on amplifiers or pre-amps that are only designed for MM pickup.

You might also want to avoid budget valve based RIAA preamps or at the least research those before you purchase, most of the cheaper valve based phono preamps have a limited bass response, this is due to the limited open loop gain available and techniques used to rectify this often induce phase errors.

Currently manufactured RIAA correcting preamps

Acoustic Signature
Makes the Tango Phono, it is an op-amp based high end device with an external PSU that supports both MM and MC cartridges and has switchable resistance and capasistance values from 10 to 1000 ohms and from 50 to 350 pF, more info here.

Air Tight
Makes the ATE-2 MM phono stage, a ultra high end, PCB less valve based unit that sports 3 inputs (so it can act as a preamp). More info here.

Althea Música
Has the Royale Phono Stage a high end valve based unit with that has balanced connections in addition to the usual, but it supports only MM pickups and is intended to mate with the Althea Música Imperial Transformer, internally it Dual Mono and more info can be had here, the company also has the Imperial Phono Stage but according to the company's web page there is no difference between the Imperial and the Royale except for the casing material.

High end phono preamp, good reviews in the press, more info.

Antique Sound Laboratory
Manufacture the MG Phone DT, it's a valve based unit that appears to support MC units only but does sport an extra 2 line inputs and a volume control so it can be used as a simple preamplifier, they also make the Pro-Phono 1S that has similar features and specifications but is made out of premium parts and has a high end external power supply.

Art Audio
Makes basically 2 valve based phonostages, one is Vinyl One, a pure class A design with a valve rectified power supply that you can get in a variety of versions from a MM only variant, to versions that support both MM's and MC's and variants with gain control, there is no real info on the web from the company but you can read a review of the unit here. they also make the Vinyl Reference a hgih end model that I understand is the same basic design but allows for ajustments of operating parameters such as gain, impedance etc..

Makes a high end Phonostage.

Asthetics (Distributors link)
Has an MC preamp.

Audio by Van Alstine
Has a range of nothing less than 4 phonostages including the FetValve unit that use a hybrid valve/transistor circuit, the solid state OmegaStar and the valve based Super Pas 3i and the Super Pas 4i buffered version. Note that none of these support MC cartridges.

Audio Experience
The company has a valve based phono preamplifier in the form of Concerto, that unit is basically just a MM premplifier with a set gain of 54dB and the usual 47k impedance but unusually enough for a high end home audio unit also offer alternative compensation EQ curves to the usual RIAA one, namely FFRR, NAB (Columbia) and Single Play, another slightly unusual feature is that the power supply features valve rectification. AE also has an improved version called Concerto Plus that features better finish and more expensive components.

Make the Phono 1, it can handle both MM and MC carts and the MC part will automatically adjust between 10 and 100 ohms, you can read a review by Enjoy the music here.

Audio Research
Makes the PH 3 phonostage.

Makes the PP-70, a high end preamp that is designed to work with MM pickups only, this is a hand built device weighing in at a whopping 6 Kg. and has a price tag to match .

Audio Synthesis
Manufatures the Passion phono stage, it's a discrete transistor model.

Audio Technica
Makes the low cost AT-PEQ3, it has got some fairly nice reviews especially regarding price/performance ratio but it will only work with MM or high output MC designs.

Audio Tekne
The company makes a number of all-valve transformer coupled pre-amplifiers and is best known for their sublime but extremely expensive TEA-9501 which is simply the biggest, baddest and costliest pickup pre-amplifier ever made, it is a Mono unit so you will need 2 for a setup and each is 63 kilograms so the pair would be 126 kg (or close to 300 pounds). The 9501 has 2 inputs, one suitable for a low or very low output pickup and a “high” input suitable for a low/medium output pickup, note though that the max input is only 85mVrms so some medium output pickups will be overdriving the unit.

Audio Tekne TEA-9501 technical specifications
Inputs : Phono low & Phono high. Outputs : 1x Balanced XLR and 1x Unbalanced cinch. Max input voltage : 25mVrms (low in.) 85mVrms (High in.) both @ -0.6dB 1.6Vrms/13Vrms (max). RIAA deviation : +/- 1.5dB. Size : 75x22.5x24 (WHD). Weight : 63 kg.

Bakoon Products
Has at the least 1 model of a preamp.

Balanced Audio Technology
Makes the VK-P3, the VK-P5 and VP-P10 valve based preamps.

Makes the valve based PP-21 phonostage.

Benz Micro
Make a tiny phono preamp called Lukascek PP-1 T9 that has an almost cult like following and has also been getting some great reviews recently (Like the golden ear award from Absolute Sound in the USA), it sports an external PSU and is optimised for MC cartridges (will probably not work with some MM's) in order to simplify the signal path.

Makes the dual mono phono preamplifier 42, sports symmetrical inputs and optional symmetrical outputs, gain is select able from 58 to 64 db, works with both MM and MC carts and supports IEC EQ in addition to RIAA.

Blue Circle
Makes a phono stage amongst other things, has been reviewed by Vinyl.

Makes a low budget preamplifier called model M that is meant to be integrated into turntables or amplifiers but can be used standalone.

The Brassany RIAA pre-amplifiers
Czech gentleman Jan Brassány makes 3 valve based high end pre-amplifiers all based around the same chassis and basic circuit but with different price ranges and capabilities. The cheapest model is the BR03MM which has an RRP of 1000 Euros and offers 40db of gain and an imput impedance of 47pF kΩ making it suitable for moving magnet pickups only. The BR03MC is identical to the BR03MM except it has 60dB of gain and an impedance as low as 1 pF 47pF kΩ which should make it compatible with all moving coil cartridges on the market with the exception of a few ultra low output ones, it has an RRP of 1160 €.

It should be noted that our understanding is that the moving coil capable Brassany compensation amps can be used with any MM or MC cartridge that fall within their specification, i.e. that they have some sort of switchable input impedance and gain structures. However the technical information supplied by the company is a bit skimpy, it does not supply pictures of its products and since they are only currently distributed in the Czech and Slovak republics we have not been able to get close enough to them to verify this for certain. The top of the range Brassany model is the BR04, in addition to having greater gain of 65dB which should make it compatible with just about any pick-up on the market, it has an improved external power supply that not only should make the unit sound better but should also mean less electrical interference from the power transformer, but valve based high gain stages are notoriously sensitive to electrical and magnetic interference. The RRP of the Brassany BR04 is 1960 Euros

Resources: Technical specifications of the Brassany pre-amps from the horses mouth, in Czech..

Makes the BP-15 phonostage.

Makes a dirt cheap phonopeamp called BT 26, retails for 30€ or so, and the better specified BT 926.

Canary Audio
Manufactures a high end valve based preamp called CA-400, there is not a lot of information to be had on the unit from the company except that it has supports both MM and MC pickps and comes with an external power supply.

Make at the least one preamp.

Has the low/mid priced Micro/Basic and Basic preamps, noticeably these 2 support both MM and MC carts, the mid range models are the Phono and Symphono note that the Symphono is for MC carts only and so are the high end Balance and Reference models.

Has the valve based PM 1 preamp, supports MM or high output MC's only.

Coph Nia
Make a nice looking RIAA preamp.

CR Developments
Makes no less that 3 RIAA preamps, the valve based Hestia, the transistor based upmarket Themis and the more budget Argento.

Creek Audio
Makes the OBH8 MM preamp and the OBH-9 MC preamp, both are fairly keenly priced units available with a either a OBH1 or OBH2 power supply (the same as are used by their preamplifiers) and both models are also available in SE versions that feature better quality components. You can upgrade the units by replacing the OBH1 supplies with a OBH2 model at a later date.

DaVinci Audio
Makes the Grandezza preamp, its a high end valve based unit that supports MM only (the company has a MC transformer to go with this unit) and features a feedback free, 4 stage pure class A topology and balanced outputs.

Makes the DP01 & DP02 phono boxes.

Makes a valve based phonostage.

This Italian maker has basically 3 systems on the market, best know is probably the transistorised MM70 which is availabe in 2 versions namely the MM70 MM that will work with MM designs and the MM70 Mc that is designed to work with low and mid output MC designs, the total gain that version gives is 62dB which means that while it will work with most MC designs it will not work with some very low output pickups , it also has a fixed impedance of 150 ohms. .

Dynamic Precision
Makes the BPC 7.3phono amp.

Esoteric Audio Research - Yoshino (EAR)
Have the 834P valve based phonostage in 3 differnt versions, the basic 834P Normal supports just MM carts while the 834P Signature supports MC as well, the 834P Deluxe is a variant of the Signature that has a better external finish.

Final Labratory
Makes a high end Music 4, but that is a MC only battery driven design that has a fixed imput impedance of 560k ohms and a 40dB gain. The design is a bit different, for instance the it features no capacitors bigger than 0,2mF in order to gain speed.

FM Acoustics
Makes 2 ultra high end phono preamplifiers, namely the high end Resolution Series 122 Precision Phono Linearizer MkII and then there is the Resolution Series 222 Precision True Balanced Phono Linearizer MkII which is one of the most expensive phono stage ever, those models support both MM and MC pickups and unusually enough for a high end audiophile preamps they have support for the correction curves other than RIAA enabling their use with early microgroove pressings and78's, furthermore both can be used with just about any cart due to flexible loading options. Note that the 222 does not come with a power supply, it meant do be driven by a FM 266 amp although you can also use a RS 202A power supply to drive it as well. I have not been able to find any publicised reviews of these models but the hompage has a number of user qoutes.

Golden Middle
Makes 2 valve based phonostages that are fairly keenly priced for the genre, both have an external power supply.

Graham Slee Projects
This company more or less specialises in making phono preamps and related products, they make 2 budget preamps the Gram amp 1 and Gram amp SE. The GA1 version does support MC but the SE does not otherwise they are identical. A slightly updated version of the GA1 is appropriately called Gram Amp 2 and is slightly more expensive than the older version and the company also produces a high end preamp called Era-Gold. For 78 Rpm enthusiast the company makes a version of the GA2 with EQ that better fits FFRR and other pre RIAA records, it's called Gramp Amp 78 and at the same price and specs as the GA2 has to be something of a bargain. Finally they make a more versatile unit for avid 78 collectors called Jazz Club that allows you to switch between differing Eq curves.

Has a high end preamp that supports both MM and MC carts, is internally a dual mono configuration and has got excellent reputation in central Europe.

Makes the Legato phono stage, like all their other products, visually stunning.

Heed Audio
Makes the keenly priced Pulsar preamp, it features a dual-mono design with an all discrete construction, for MM carts only. The Quasar however is a more versatile device altogether with a separate stage for MM and MC, for the moving coil section both load and sensitivity can be adjusted and the unit has both a line output and a "high out" to drive power amps directly.

Make the HA-EQ1 MC preamplifier, more info here.

Makes 2 preamps, the Ellipse, a mid price unit that supports both MM and MC carts and looks lovely (Has a wooden cherry or black front and sounds great according to the Germans, something of a class leader if I understand it correctly), and the Batteriaa Limited Edition a cleverly named high end unit that is driven by a rechargeable battery and supports MM/MC carts.

Joule Electra
Makes a high end premp called OPS1 Mk.III, that unit has been reviewed by soundstage.com.

Makes the Viv valve based phonostage, this is an excellent sounding unit, very smooth and warm if a little dear price wise as all quality valve based stages have a tendency to be, it can be driven by just about any cartridge including very low output MC units, but as with valve units in general if the MC output is less than 0,3mV or so you start to hear a little noise, so if your pickup has much less than a 0,2mV output a high quality, low/medium gain transformer is not a bad idea, actually a high gain transformer will do fine if you already have one as the input on the Viv/Merlin is very forgiving, even connecting a high gain tranny to a medium/high output carts did not manage to overload the input, unusual and a sign of a quality design. Note that you can get this phono stage built into the company's Merlin preamp, more info on that see Klimo valve amplifiers.


Makes the KPE in a "Standard" and "Reference" versions, both are high end models and are intended to get power from a Krell amplifier but can also be had with a separate power supply. the Reference is a MC only device that comes standard with a 70db gain (but is adjustable and offers 58, 64, 70 and 74 db), the Standard works with both MM's and MC's.

Lehmann Audio
Makes a mid range model called the Black Cube a unit that supports both MM and MC pickups, it's a clear class leader and has become something of a benchmark amongst reviewers and other preamp manufacturers, almost every time I read a evaluation or a manufacturers sales pitch about their RIAA amp the Black Cube gets a mention there somewhere and that pretty much say's it all about the price performance ratio of this preamp, you can read an old review of the unit here. There is also a version available with an improved power supply called Black Cube SE, current owners of the Cube can also upgrade their system by getting hold of the supply, as a separate product it's called PWX. The company also makes the high end Silver Cube, it has also got excellent reviews but is almost 5 times more expensive than the original Cube, it has also recently introduced a model called Black Cube SE Twin but I have no info on it.

LFD Audio
Makes the high end MC1 and MC2 phonostages, these support only MC pickups and feature external power supplies (yes 2 in one box, one for each channel), the difference between them is that the MC 2 has custom made passive electronics, more info on them here. The Phonostage MMO is however a self contained unit that supports both MM and MC pickups but is also a dual mono design as the more expensive models, gain for MC's is 53db so it will not suit very low output carts. The Mistral phonostage has a much keener price than the other units from the company, it has a similar design to the MMO but is built using IC rather than using the all discrete construction of the other models.

Makes a mid/high end preamp called E-03, it can be used with MM pickups and MC pickups with as low an output as 0,2mV, in addition the Japanese market gets the E-1 a high end model that has most adjustments available from the outside and thus better suited with use for multi cart setups.

Make the Garrard Missing Link preamp, it's mid priced and available in 3 versions, one suitable for MM pickups and 2 intended MC carts with impendances of either 100 or 470 ohms, you can also get the Missing Link Switchable that is slightly more expensive than the plain models but can be switched between the above 3 characteristics, there is also a version of that model available that supports 22, 47 and 220 ohms in addition and is called Missing Link Professional. Note that the Lorricraft company publishes no gain specifications for their amps so it's impossible to judge what pickups they are compatiable with. The company also produces the The Archivist Professional Phono Equaliser which is intended to allow the playback of .

Makes the Magenta FZ47db preamp, features 16 switchable impedance settings from 16k to 390k and is totally discrete, it has been reviewed by the Vinyl Word.

Manufactures the Micro-Phono preamp, it's suitable for both MC and MM's and has variable input impedance. It was reviewed in Hi-Fi News Magazine issue 8 1999, p49.

Michael Yee Audio
Makes the PFE-1 a dual mono a high end unit that has a switchable gain from 40 to 60dB and impedance from 15 to 15K Ohms, this means that it will work with any MM and MC design except for a very few ultra high end pickups with very low outputs and impedance's (impedances can go as low as 1 ohm and very low output pickups need a minimum of 62dB gain), the impedance switching on the unit is particularly impressive since there are 60 different settings available which may sound like overkill but some MC designs, in particular vintage Japanese ones that have an optimal impedance of around 100 ohm are very fussy about the loading so having a option on the preamp saves you from having to solder resistor arrays on the input.

Michell Engineering
Makes the Delphini preamp, it features an external power supply that is available in 2 versions so you can start out with the cheaper version and upgrade later, the input impedance is switchable from 33 ohms to 47k ohms and can handle both MM and MC carts. You can read a user review of it here.

Musical Fidelity
Makes at the least one RIAA preamp.

Musical Surroundings
Although primarily a distributor this company makes one product and that is the Phonomena phonostage. It sports adjustable loading and gain amongst other features. You can take a look at a review of the unit by Stereo Times here.

Makes the PP-1 phono preamp, excellent for the price and better built than most units in the price range.

Offers the Prefix and the Stageline phono boxes, The prefix is designed to be built into a turntable plinth while the Stageline is an external model that is manufactured in separate MM and MC versions, neither model comes with a power supply but has a connector for a separate Naim power supply or alternatively can be powered by one of their amps, you can download a manual for the Stageline here.

The company makes 2 high end units simply named Phono1 and Phono2, both unit appear broadly similar except that the Phono2 features an external power supply and can for even better sound quality be driven by two for a fully Dual Mono operation. There is not a lot technical info supplied by the company except that they state "The NVA Phono1 can be matched precisely to any cartridge of your choice", it is not clear if this means that means that NVA supplies them to order with the amplification and impedance characteristics to suit your cartridge or if the units are fully user configurable, the former seems more likely but contact the company for further info, more info on them here. Note that the company calls them head amplifiers but they are actually phono stages.

Oehlbach Kabel
Has a fairly recently introduced model that retails at a rather keen price and has had some good press but I have not been able to find any technical details for at the moment, but it does support MC pickups in addition to MM.

Make a high end j-fet based phonostage called InTheGroove MkII, it features dual mono operation, balanced outputs etc. and is the only product from the company that does not feature valves, MC capable BTW.

Make the Phono Box, a rather nifty low budget box that is built up as a dual mono unit electronically. Compatible with both MC and MM carts and has automatic impedance matching. Must be considered to be something of a bargain.

Apparently still make their fab low cost RIAA preamp although it's not listed in their catalogue nor on their homepage, but distributors seem to be able to supply it.

Red Rose Music
Makes the Roseette 2, a high end amp that has a separate power supply one neat feature is that the MM and MC inputs are separate and thus you can have both connected at the same time while switching between them via a front panel knob.

Makes the fono preamp, it supports both MM and MC designs.

Makes the Caspian Phono Stage also available in a Caspian Phono Stage SE version, these are firmly targeted to in the high end, the SE version is more expensive than the Caspian amplifiers for instance.

Makes the RQ-970 BX phono preamp that has been getting very good reviews esp. for price/performance ratio, works with both MC and MM pickups.

Rudi Stor
Has a battery driven dual class A preamp called Opus 100 phono, it' MM capable only.

Special Audio Components (SAC)
Makes the Gamma phono preamps.

Makes the high end MM 20 preamp for MM or high output MC carts and the MC 20, while the site states that the MC20 is only for MC's I think that it has an internal switches for impedance and gain and thus should work with both MC's and MM's.

Silvaweld Audio Lab.
Makes the SWH-550 MC/MM capable phono stage, the amplification stage is valve based but unusually also the external power supply and the unit has a switchable input load impedance for MC carts, there is a host of other high end technical features such as de-coupled PCB's and silver wiring internally.

Makes a preamp intended for soundcards , but the line levels are the same as for hi-fi systems, a bit easier to find that most other models..

Makes a range of preamps including the MM 001 a fairly cheap and simple unit that works with MM pickups only, more info here, they have more recently introduces a high end model named TEP 302 which has provisions for both MM and MC models, gain is 40 and 60dB, this means that it might not work with all high output carts unless you add extra low value resistors of your own, the TEP 302 however does have switchable impedances.

Tiny Tube
Makes the valve based Riaa preamp, has got good reviews in the Danish hi-fi press.

This turntable specialist has a preamp called simply Phono Preamp (actually "Phono Vorverstärker" but you know what I mean), a well liked unit but I have not found any review of it online.

Trichord Research
Makes the Dino and Delphinis preamps.

Makes a valve based preamp.

Tsakiridis Devices
Makes 2 phonostages that supports MM devices only, the valve based Zeus Tube a keenly priced valve phonostage and the op-amp based Zeus, more info to be found on the Zeus here and the Zeus Tube here.

Unison Research
Makes the valve based Simply Phono preamp.

Vad Lyd
Makes a high quality preamp that has Eq. curves that can correct RIAA and also earlier formats used by 78's and early LP's such as FFRR etc., by far the most versatile of such units that we have seen.

Walker Audio
Makes a phono stage.

Wavelength Audio
Makes the Tangent hybrid phonostage.

Has a few very interesting high end designs on the market, while I have not had the good fortune to try them out they bear some obvious hallmarks of careful design, first is the Diamond 36 an MM and MC capable dual class A preamp, that offers switchable capacitance between 50 and 420pF and an input impedance switchable up to 100/150 Ohm (in MC mode, more in MM mode obviously), the MC gain is 61.5dB, a variant of it called Diamond 36 Studio is identical expect that it has a more precise RIAA correction and offers impedance of up to 475 Ohm. Both units come with a power supply but can be upgraded to a higher specification by adding the Power No. 48 power supply. The top of the line Consequence No.96 is however a hybrid valve/transistor dual class a design and comes with 2x Power No48 supplies as standard, it has the same input options as the Studio version of the 36. Take a look at the specifications, some of the most impressive I have seen for a valve based phonostage.

Williams Hart Electronics
Make a legendary RIAA preamp designed by John Linsley Hood that is both available in kit form and fully built, it was originally designed in the late 80's and is starting to show it's age a bit but still nice, and nota bene it has selectable gain and impedance so it can be used with most MM and MC designs. One user has review of it here and another one here.

Wilson Benesch
Make the Stage 1 phono preamp.

Wright Sound Company
Makes the valve based WPP100C preamp.

Yamamoto Sound Craft
Makes the CA-01 and CA-02 phono stages.

Makes a high end phonostage.

47 Laboratory
Take a look at their 4712 Phonocube, it's a high end, dual mono phonostage with MC capabilities, for users of cartridges with exceptionally low output there is a version available with 90db gain.

Optional RIAA modules

Quite a few companies that do not ship their amplifies with a phono input do sell modules that will integrate into their amps, apart from the convenience these are often extremely good value versus a separate phonobox so if you have an amplifier from one of the companies listed below you should check them out before investing in a separate unit.

Audio by Van Alstine
None of their preamplifiers ship with built in phono preamps anymore but they will supply one as an option, that RIAA preamp is a bit controversial soundwise, people either love it or lothe it but cetrainly worth a look if you are in the market for a AVA preamp.

Manufacture the Phono Multi Solution board that supports both MM and MC pickups in fact it has separate inputs for each type with a select able impedance on the MC input, apparently this unit will work in all of their amplifier products including multi cannel systems.

Creek Audio
The company makes the MM Phonoboard, MM SE Phonoboard, MC Phonoboard and MC SE Phonoboard, these are cards that will fit into any recent Creek integrated amplifier, the SE versions have better components than the normal versions.

Makes the P-50 which is intended to fit the Dynavector L-200, it is avalable in both MM and MC capable versions, both are DC coupled, the MC versions impedance is fixed at 100 ohms (fine for Dynavector or Denon pickups) but unusually enough has a sockets for external resistors to compensate for this.

LC Audio
Makes the RIAA Modul a small preamp that is intended to be integrated into the preamplifier section of your amp although it could also be put into a separate box, available in versions intended for MM's or for both MM's and MC's, for some reason there is no information on it on their English page but there is information in Danish here.

Makes a board for their Cursa 2000 preamplifier, it's available in both a MM and MC version.

RIAA preamp kits
Many traditional kit producers make available inexpensive RIAA correcting modules, amongst the better ones are the PAIA Electronics unit that is under 30 US$ and is recommended especially for those of you based in the USA, but it should be noted that the most basic of these kit's are not really worth buying since you can usually get something similar at your local electronics store fully built for the same or less.

Audio by Van Alstine
Makes their the valve based Super Pas 3i and Super Pas 4i phonostages available as kit's as well as fully built.

Borbely AudioHas 2 phonographic preamps available, the low cost EB804/419 that supports both MM and MC carts and the EB199/320 which is a higher class design but appears to offer only support for MC pickups. Additionally they have the hybrid valve transistor EB1195/221 that supports both MM and MC

Williams Hart Electronics
Their Williams-Hart phono stage is available in a kit form at considerable savings

DIY RIAA preamps

Phono stages are one of the most popular DIY projects out there, not surprising since they are reasonably simple and inexpensive to build, but have a lot of potential for tweaking.

AML+ Preamp
Actually a fully fledged preamplifier but the most interesting aspect of this Russian valve based design is the RIAA correcting amp

Transformer coupled, valve based stage, actually a modification of the RCA circuit listed here above. Designed by Chris Beck and you can take a look at it here

A very interesting dual mono transistorided preamp design, the most complex design I have seen yet, more transistors and caps than in some of my synths

TNT InDescreet

Sundry designs
The application note (PDF) for the LM833-N audio op-amp from Texas Instuments has simple but a surprisingly good sounding 2 stage RIAA amp, needs a half decent power supply to be at its best though. — The EB-199/320 by Ernö Borbély is much more interesting however, it's a MC capable phono stage based around JFET opamps and actually sounds quite good. While it has regulators the author recommends that it is battery powered. — One legendary preamp design from the 60's was the 7 stage design by Linsley Hood and published in Wireless world, I have been trying to track it down on the web to no avail, but a couple of later design variations of his are available from this page, you will need to scroll down a bit, a simple design is around the middle of the page and a more complex one near the bottom.

Valve based DIY designs

RIAA pre-amps are an excellent introduction to the world of thermionic valves, unlike full amplifiers you can get a functional phonographic pre-amp using as little as one valve and a power supply, and there is no need for the output transformers you see in normal amplifiers. You will need to be aware of one thing however, a basic valve based gain circuit has limited open loop gain and therefore using the sort of passive RIAA compensation (EQ) that you see in transistorised pre amplifiers will result in a somewhat weak bass response

This is not the end of the world they can sound fine even if a little bass light, the reason that these simple pre-amps prevailed back in the heyday of valve audio was simply that most playback equipment had a rather limited capability to play back bass anyway, however even budget modern gear is capable of going down to 70Hz or less with some linearity so results may disappoint. There is no simple way to fight this, modern valve based preamps are simply much more complex than the classic designs, you will sometimes see simple passive or one valve active solutions to this, but they invariably induce phase errors which was not a problem in mono gear but is audible and annoying in stereo. This should not discourage anyone form playing around with valve base preamps just make people aware that if they are looking for a simple start is the “wonders” of phonographic pre-amplifiers, a transistorised design really is the way to go.

AKRAM passive and partly active RIAA pre-amps
Icelandic company AKRAM used to have schematics and technical info on valve based pre-amps on their homepage, but it went down with the rest of their pages, thankfully the Internet Archive has a copy here. There are two basic schematics, one is a traditional valve based circuit that has the usual passive compensation and the other has active compensation for the bass only.

Sundry designs
The good old RA-100 DIY valve amplifier design by Fred Nachbaur also incorporates a valve phono stage that can be built separately. — Another classic designs was Bob D’s valve phonostage, it was originally placed on the net in 1995 but fell off it when Geocities was closed in 2009, however the Internet Archive has a copy here, this one is simple three stage design that is at is based on the old RCA application note and features a couple of of 12SN7 GT and 12SL7 GT light bulbs. — A slightly updated version of that design can be found here and on the same site you can find an archive of the construction articles for the

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The site was last compiled on Sun Nov 10 2013 at 9:15:00am