RuffRecords' PCB Emporium

Welcome to Ruffrecords' PCB Emporium. Here you can purchase any of the PCBs for my various GroupDIY projects as well as other general purpose PCBs such as the tube HT PCB. Here you will also find links to the documentation for each project and to the original threads on

To order a PCB just drop me an email at with a list of what you require, your name and shipping address. I will respond with an emailed PayPal invoice for your order. Just click on the Pay Invoice button to pay the invoice and I will send you the PCBs.

Please note that all prices are in GBP and shipping is charged at a flat rate of 2GBP for UK, 3GBP for Europe and 4GBP for the rest of the world. 

Price List


Order Code



Poor Man's EQP1A




Poor Man's Mid




Poor Man's Tube Gain Make Up




Phantom power supply




HT Supply




3 Band Pultec (original)




3 Band Helios Type 69




EZ Mixer Eurocard




Helios 69 EQ, 3U version




Universal EQ




REDD EQ, 3U version




Twin Line Amp




Lorlin Switch Header




Grayhill Switch Header




6 Module Backplane




DB25 summer




2 Module Backplane V2




Classic Mic Pre




Project Descriptions

Poor Man's EQP1A

Many people have built clones of the Pultec EQP1A passive equaliser. However, it is quite expensive to build because it uses several transformers and an inductor. The idea behind the Poor Man's EQP1A is to keep most of the features of the original but at much reduced cost. The core PCB (PMEQP1A) uses a low cost 2 pole 6 way switch that can be built as either the hi or lo boost/cut frequency select. The circuit has been modified so that no inductor is needed which means that two of these PCBS and just four pots make the entire EQ.

As it is a passive EQ it needs a gain make up amplifier and many constructors have used a low cost op amp for this. If you want to go for tube based gain make up you can use the Poor Man's Tube Gain Make Up PCB (PMTGMU) which uses a single tube instead of the two in the original. No interstage transformer is required and an output transformer is optional. (You can now also use the TwinLineAmp PCB – see below).

The power supply for the tube stage can be built using normal point to point wiring or you can use my HT Supply PCB which holds the rectifiers, RC smoothing components and and heater elevation supply.

As a result of many requests I was eventually persuaded to develop a mid boost/cut option which is now available as a separate PCB (PMMID), Unfortunately there is an error on these PCBS but there is a workaround which is included in the documentation so this PCB is still quite usable. The workaround is only necessary if you use the specified inductor from Carnhill. If you use the inductors made by Chrion for GroupDIY then no modification to the PCB is necessary.

Documentation for the Poor Man's Pultec can be found here:

The original group DIY discussion about the design of the Poor Man's EQP1A can be found here:

The groupDIY support thread for this project is here:

The groupDIY discussion thread leading to the addition of the mid boost/cut can be found here:

The groupDIY discussion about the poor man's tube gain make up stage is here:


This project grew out of the need to extend my standard mu follower based mixer designs to include flexible per channel EQ, direct outputs and pre and post AUX sends. Mu follower designs cannot meet all these objectives because of their fixed gain and limited drive capability. So a new variable gain, high drive capability amplifier design was required and the result forms the basis of the EzTubeMixer. The core PCB (EZMIXERV3) is a standard single Eurocard sized PCB that holds two identical amplifiers, The first, which acts as a mic/line preamp has additional input signal conditioning (48V, phase, pad and mic/line switch), a HIZ instrument input option, a microphone input transformer and a 12 position stepped gain switch covering a 26dB to 60dB range. The second amplifier has a pre-set pot for gain setting and is intended primarily for gain make up after EQ and/or a fader.

Together with separate passive EQ PCBs (3 band Pultec and Helios 69), this Eurocard can be used to build a complete all tube channel amplifier. The rear of the PCB has a 32 way 0.2inch pitch connector that provides all the input/output and power connections required along with provision for four mix buses.

A derivative of the Eurocard amplifier is the Twin Line Amp. The removes the mic pre specific components i.e. the gain switch, push buttons and HI-Z relay and instead has provision for two input transformers. These can be either 10K:10K types for line inputs or a 1:10 type for mic and balanced summer inputs. The PCB is laid out so either Sowter, Cinemag or Jensen input transformers can be fitted. The heater wiring has also been modified so that by changing some links, the output tubes can be changed to ECC99 types for driving headphones.

Without transformers this PCB can be used as a passive mix bus gain make up amplifier. With 10K:10K input transformers it acts as a twin balanced line input (with optional EQ) card. With a mic input transformer it can be used as a gain make up amplifier for a balanced summing bus or, by fitting an external gain switch, it can be used as a pair of microphone preamps.

Documentation for the EzTubeMixer can be found here:

The groupDIY discussion of the Poor Man's Tube Mic pre (which becaome the EzTubeMixer) is here:

The subsequent discussion about the EzTubeMixer is here:

Documantation for the TLA is here

Universal Passive EQ

This project was developed to allow people to build a variety of different passive EQs simply by configuring a single PCB and adding appropriate gain make up. A group buy was set up for the project and now that is complete the remaining PCBs are available here. As part of the same project Lorlin and Grayhill Header PCBs were developed to simplify the connection of external rotary switches to the PCB. These header PCBs were also made available through a group buy and the remainder are now available here. Documentation for the Universal Passive EQ can be found here:

DB25 Passive Summer

The DB25 summer PCBs were developed to fulfil my own need for a balanced passive summing board that would attach directly to a DB25 connector. The boards conform to the Tascam 8 channel balanced input connection standard and can be daisy chained to increase the number of inputs summed. Each input can be fitted with resistors that allow it to act either as a left or right channel or as a mono channel. It turns out lots of people wanted just the same thing so I have made them available here. Documentation for this PCB is within the groupdiy thread here:

If you have any questions, please feel free to email me at or post on the appropriate thread at