Ruffrecords PCB Emporium -- Sifam PB 01/51/000 Keycaps available

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 GroupDIY.com.

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

Stock changes rapidly so I am keeping a separate document of the current stock levels and prices (including any special offers). Check out the the Ruffrecords PCB EMporium page at my new web site

http://www.customtubeconsoles.com/ruff-records-pcb-empporium

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.



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.

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: http://www.ianbell.ukfsn.org/EzTubeMixer/docs/PMEQP1A

The original group DIY discussion about the design of the Poor Man's EQP1A can be found here: http://www.groupdiy.com/index.php?topic=43859.0

The groupDIY support thread for this project is here: http://www.groupdiy.com/index.php?topic=44213.

The groupDIY discussion thread leading to the addition of the mid boost/cut can be found here: http://www.groupdiy.com/index.php?topic=45475.0

The groupDIY discussion about the poor man's tube gain make up stage is here: http://www.groupdiy.com/index.php?topic=43973.0


EzTubeMixer

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.

This same Eurocard amplifier PCB is also used for gain make up for passive mixing, and by simply changing two tubes and some passive components, converts into an all tube stereo headphones amplifier.

Documentation for the EzTubeMixer can be found here: http://www.ianbell.ukfsn.org/EzTubeMixer/docs/EzTubeMixer

The documentation for the 3 Band Pultec EQ PCB which will do everything that the poor ma's Pultec will do and more can be found here: http://www.ianbell.ukfsn.org/EzTubeMixer/docs/EzTubeMixer/3BandPultec/

The documentation for the new Helios 3 band EQ can be found here:
http://www.ianbell.ukfsn.org/EzTubeMixer/docs/EzTubeMixer/Helios69EQ/

The groupDIY discussion of the Poor Man's Tube Mic pre (which becaome the EzTubeMixer) is here: http://www.groupdiy.com/index.php?topic=47424.0

The subsequent discussion about the EzTubeMixer is here: http://www.groupdiy.com/index.php?topic=48039.0


Support thread for builders of the EZTubeMixer is here: http://www.groupdiy.com/index.php?topic=51829.msg658803#msg658803

db25 summing PCB

This project arose out of my own need for a simple interface between a Tascam standard 25 way D-type connector and a balanced summing bus. Surprisingly nothing like this is available right now (Holger had a design but not the time to update it) so I did my own. A couple of these, a couple of XLRs and a handful of resistors and you can build yourself a balanced passive summer.

The original thread is here:

http://www.groupdiy.com/index.php?topic=52068.msg663009#msg663009

If you have any questions, please feel free to email me at [email protected] or post on the appropriate thread at groupDIY.com

Cheers

Ian

Ian congrats on the White Market page! It's great to see all your designs in one spot. 'm diggin the 3 band pultec board.
As an early adopter of the PMEQP-1A and the separate mid board, I really like where you have taken the project with this PCB and I think I might have to get another 2 channels!

Dave

Sorry if this is the wrong place for this, but I couldn't find the info anywhere else.... I'm interested in building the whole helios channel strip (possibly to make a mixer out of that chassis I have) The mic pre side won't be that hard. transformer, two line amp cards that are easily perfboarded.... am I correct in thinking that I could put your eq board in between there and have the whole strip working? or have you modified it? Thanks


Ken

kpearsall said:

Sorry if this is the wrong place for this, but I couldn't find the info anywhere else.... I'm interested in building the whole helios channel strip (possibly to make a mixer out of that chassis I have) The mic pre side won't be that hard. transformer, two line amp cards that are easily perfboarded.... am I correct in thinking that I could put your eq board in between there and have the whole strip working? or have you modified it? Thanks


Ken

Click to expand...

You are right the info is not anywhere else. I am assuming you mean can my EQ board be put between original Helios design semiconductor line amps? The answer is yes you can. My design closely follows the original but I have changed EQ component values to work with currently available inductors and added extra frequencies to the bass and mid EQ. Other than that it pretty much follows the circuits you can find on the net.

Cheers

Ian

great news! thanks, that is exactly what I meant... I'll pick a few to test up from you in a couple weeks.

Just updated the documentation for the 3 band Pultec to include a BOM. New pdf is here:

http://www.ianbell.ukfsn.org/EzTubeMixer/docs/EzTubeMixer/3BandPultec/P3bandDoc.pdf

I'll be doing the same for the Helios version over the next few days.

Cheers

Ian

Put me down for a couple of Helios boards please.

[quote author=ruffrecords]OK, you are on the list. I'll bill you when I get the switches and send them all together if that is OK with yo.[/quote]
Thats fine by me, thanks

mrclunk said:

Put me down for a couple of Helios boards please.

Click to expand...

OK, you are on the list. I'll bill you when I get the switches and send them all together if that is OK with yo.

Cheers

Ian

For those interested in building the Helios or 3 band Pultec PCbs or the Eurochannel mic pre, I have added preliminary BOM/costings to the EXTubeMixer documentation so you can get an idea of what the total project cost is likely to be. Totals are approximate because they depend on things like which mic transformer, pots and knobs you choose to use.

Helios/Pultec BOM costings are here:

http://www.ianbell.ukfsn.org/EzTubeMixer/docs/EzTubeMixer/PultecHeliosBOMs.pdf

Eurochannel BOM/costing is here:

http://www.ianbell.ukfsn.org/EzTubeMixer/docs/EzTubeMixer/EurochannelBOMcost.pdf

The original LibreOffice .ods files are in the same directory if you want to use them as the basis of your own BOM.

Al the documentation and ordering information can be accessed from my mini web site here:

http://www.ianbell.ukfsn.org/EzTubeMixer/

Cheers

Ian

For those building the Helios69 EQ PCB, I have just updated the documentation to cover the connection of the mid boost/cut switch and to correct a minor error in the silk screening of the PCB. Updated documents, version 1.1 can be found here:

http://www.ianbell.ukfsn.org/EzTubeMixer/docs/EzTubeMixer/Helios69EQ/

Cheers

Ian

PCB's arrived yesterday and look really great! Thank you

The first batch of  the EZTubeMixer V3 PCBs have arrived. This will take a Sowter or Cinemag or Jensen mic transformer.

Cheers

Ian

Just received my boards today! Thanks so much Ian! I'm really greatfull for all the work you put into this, to make this available is incredible and generous. Truly in the spirit of a diy community. I will try to help in anyway i can. Once i have a north american bom figured and tested i'll make it available. Maybe i could post a step by step with pictures, once i get a few channels done.
I'll probably order more pultecs eventually.
Thanks again,

Pierre

I have added a preliminary version of some assembly notes for the V3 PCB here:

http://www.ianbell.ukfsn.org/EzTubeMixer/docs/EzTubeMixer/EZTubeMixerV3AssyNotes.pdf

It covers the sources of the more uncommon components and various assembly tips.

Cheers

Ian

Do you offer all the boards needed for the Helios eq Ian? Filter, amps, etc...

desol said:

Do you offer all the boards needed for the Helios eq Ian? Filter, amps, etc...

Click to expand...

In a word yes. There are a couple of ways of achieving this.

First you could go the original poor man's style route and use a 10K:10K input transformer to drive the Helios EQ PCB (HELIOS69) and then one of the poor man's tube gain make up PCBs (PMTGMU) connected to the output of the Helios EQ PCB.

If you wanted to do two channels you could either use a pair of PMTGMU PCBs (which is the cheaper option) or you could use one of the new EZTubeMixerV3 PCBs (EZMIXERV3) which contains two identical amplifiers. This PCB is more expensive than a pair of PMTGMU PCBs but it has a much better drive capability than the PMTGMU and with a suitable output transformer can drive a 600 ohm load. Unless you really need this sort of drive capability you are better off using the PMTGMU PCBs.

If you want to do a mic/line channel with EQ then the EZMIXERV3 PCB is the way to go. The first amp is used as a switched gain mic/line pre which feeds your channel fader which feeds the EQ PCB. The EQ PCB output goes to the second amplifier used for gain make up.

In all cases you can use a HT350 PCB to provide the necessary HT voltage and heater elevation.

Hope that helps.

Cheers

Ian

I have just added a pdf document summarising the results of the testing the HELIOS68 EQ PCB.

http://www.ianbell.ukfsn.org/EzTubeMixer/docs/EzTubeMixer/Helios69EQ/helios69tests.pdf

Cheers

Ian

Poor man's pultec boards arrived today, caps and pots on their way. Cant wait to build this, thank you Ian!

Hi Ian

I have been looking for info about your HT supply but can not find any info on your HT350. whats the output current  ,dc voltage , and can the user change the voltage/current by way of resistor .



cheers

skal1

skal1 said:

Hi Ian

I have been looking for info about your HT supply but can not find any info on your HT350. whats the output current  ,dc voltage , and can the user change the voltage/current by way of resistor .



cheers

skal1

Click to expand...

Yes, you are right, there is no info specific to the HT350 PCB. It is a very simple board that includes HT rectifiers, reservoir capacitor, three stages of RC filtering and a 75V heater elevation potential divider. The circuit of this PCB is shown at the top of this diagram:

http://www.ianbell.ukfsn.org/EzTubeMixer/docs/PMEQP1A/PMEQP1Ahookup.pdf

The PCB circuits start just after the transformer secondary, with the 100nF capacitor, the four rectifier diodes and the reservoir capacitor followed by three stages of RC filtering and lastly the 75V heater elevation circuit.

The values shown in that circuit are for powering a pair of poor man's tube gain make up PCBs but the PCB will accommodate capacitors up to 470uF.

As this is a very simple circuit it will work with a wide range of output voltages and currents. As a rule, I aim to have about 10 volts dropped across each resistor. So for example, I used this in a 6 into 2 all tube mixer design that consumed about 100mA so I set the resistors to 100 ohms each. The mains transformer had a 240V secondary which meant the unloaded output voltage was close to 240 * 1.414 or 339 volts (in practice is was close to 330V). With the load applied, the output voltage drops to 300V.

For lower currents you can simply increase the values of the resistor and benefit from improved smoothing or, if you wish, you can reduce the capacitance value.  The poor man's tube gain make up amp consumes about 5mA so for 2 of them I set the resistor value to 1K ohms. The only thing you need to watch is the power rating of the first resistor as this has to withstand the full in-rush current at switch on. To be safe you should use a 5 watt rated part for this component.

I hope that gives you enough to understand the intended use of the HT350 board. Please feel free to ask if this is not clear.  I think I will put together a separate schematic for this PCB.

Cheers

Ian