Frog Tube Preamp Inspired by Alembic F2b

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Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 05 Jul 2016, 16:44

If this is against the rules please let me know. I'll happily take down the post or move it to the appropriate place!

New Release upcoming of Frog Tube Preamp for Bass and Guitar Inspired by Fender/Alembic F2b

I am due to release within the next week the Frog tube preamp for Bass and guitar. It is inspired by the Fender Dual Showman and Alembic F2b. It is a bare PCB board you populate. It has been under development for about 13 months. 18 pages of documentation so far published on the http://frogpedals.com/index.php/product-documentation/ website. Some drill templates are due to be put on the site within the next day or so. You can build it with a 12Ax7 size preamp tube, or if you are adventurous, I have a solderable socket for the Russian submini 6n16b or 6n17b. It is made with 2 ounce copper plate and is a beautiful board. I have added a high-cut switch and it also includes the standard bright switch that came with the Fender and Alembic. Another couple switching options is for 6 volt or 12 volt heaters for you tube rollers. The 6 volt tubes I have used are the Russian 6n1p and 6n2p that are functional equivalents to the 12Ax7 and 12AU7. The last switchable option is, if you want to add a little dirt to the sound, you can select two different diode clipping options. The power supply is a SMPS charge pump design like a nixie power supply that keeps the board size down to 77mm x 57mm. I can't wait to share it with the world. I have already sent a few of my test production runs to two people in Canada and 3 in the USA. I have 100 more boards on the way. My website for purchasing it is http://frogpedals.com and my Facebook page is http://facebook.com/frogpedals. The shopping site will say "out of stock" but it is due in within a week. For the first 30 days, the board will be sold for $10US after that it will go to $14US. I will announce when it is available for sale on this thread and on Facebook. Feel free to ask me anything about it. You can see some completed and in process builds on the frogpedals Facebook page.
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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 06 Jul 2016, 04:38

Drill Templates for the Frog Tube Preamp are now available on http://frogpedals.com/wp-content/upload ... plates.pdf

Print the Drill template before you populate the board. Select full size on printer options. "Portrait" and "Landscape"style templates are both on one page. Templates designed for switches in off-board orientation. If you want to use the tube heater switch option, for on-board switch, lay PCB component side down on drill template and mark through center tube heater switch hole for center of switch for drill hole. You can also choose to wire heater switch off-board, just choose best location based on fit in enclosure, mark and drill. Also, I recommend an on/off toggle switch for power separate from foot stomp switch.

Should be able to open up sale of this PCB within a weeks time.
Drill templates contributed by: Christopher Timko - THANKS!

See prototype build sample below:
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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 06 Jul 2016, 15:43

Just so you can see the room available in a "landscape" orientation of the pedal enclosure, see the attached pictures.
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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 07 Jul 2016, 19:14

Good News! The new PCBs have arrived and are ready for sale on http://frogpedals.com. For the first 30 days, they will be $10US each and shipping will be essentially for one board or so, 2.75 for US, 3.75 for Canada and 4.00 for International shipping. You can order as many as you like. Please read the support page on http://frogpedals.com/index.php/support/. Support will come via this forum thread linked on support page. Product documentation and sample drill templates (contributed by Christopher Timko!) are on the http://frogpedals.com/index.php/product-documentation/ page. All payments will be done via PayPal. Let me know if there are any issues checking out and I will get them resolved as soon as possible.
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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 09 Jul 2016, 03:12

For those of you ordering Frog tube preamp boards I need your feedback. This is my first time running an ecommerce website and shipping worldwide. You should get emails from the frogpedals.com site when you order the boards, is there enough information in them to satisfy your expectations when ordering? You also get paypal order emails. Do those have the information you need when placing an order? Is there anything else that would be helpful during the ordering process? Thanks to those who have or will be ordering!

For those in the US that are ordering, make sure you fill in the "State" field of your address. There is a bug in the ecommerce software that forced me to make that a non-required field for our international friends. I am trying to work with the ecommerce site people to get that fixed, but that may take a while.

So far, I have gotten orders from Sweden, Czech Republic, France, Utah USA, Alabama USA, and in my test production run have sent to Manitoba Canada, Toronto Canada, Louisville Kentucky, and some local friends in Kansas City Missouri USA and Independence Missouri USA. As I ship these orders out, I will update the world Map page on frogpedals.com.

Thank you!
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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 11 Jul 2016, 21:23

Here is a better picture of the MillMax 917-43-208-41-005000 transistor socket. I forgot to add that the pins are gold plated.
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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby deltafred » 11 Jul 2016, 21:43

Interesting project Mark.

I have been fancying an F2b preamp for a while but having just got away from a pre/poweramp rack in favour of a class D amp (GK MB800) didn't want to schlep a racked unit.
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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 11 Jul 2016, 21:45

Go to http://frogpedals.com and download the product documentation and see if this is the right project for you. I appreciate you commenting on this! Let me know if you have any questions.
Last edited by mark.price on 11 Jul 2016, 21:48, edited 1 time in total.
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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 11 Jul 2016, 21:47

For some reason, this post disappeared a few minutes ago, so I will re-post:
Hello froggers! I am excited to try something new! For the last few years I have been looking for a suitable socket for subminiature vacuum tubes and I may have found a "current production" possibility. There is a MillMax version of socket for 8 pin transistors that are PC mount. The Mouser link is: http://www.mouser.com/ds/2/273/136-259791.pdf . The manufacturer part number according the Mouser is: 917-43-208-41-005000. The specific socket that is closest to the Frog Tube Preamp PCB submini holes is the .230 one. If you look at the pictures attached here, the socket pins are straight. In the picture where I am holding the sockets, you will see that I had to "form" or bend the pins slightly to get it to fit the submini solderable pin holes on the PCB. Once they have GENTLY been bent, they fit right in and can be soldered. I have not soldered one in yet, but I will be populating a board with this configuration and let you know how it goes. You will see by the data sheet PDF I referenced above, there are little contact clips inside each pin hole so it will make good contact. If you are going to try this, DO NOT clip off the pins once soldered and remember to solder the socket on the non-component side. Meanwhile I will be experimenting with this. The contacts are rated at 3 amps, so there should be no problem with the .6 amp heater wires. By the way, if you do put this in, point the little "bump" to pin 1 on the Frog Tube Preamp PCB for better reference and use my guide in the documentation to determine the pin numbers on the Russian submini tube. The marking for pin 1 is on the component side. Sorry about that. In future versions of the board, it will be on both sides. The good thing about this, if it works, is that you won't have to solder a submini tube permanently into the board! Another thing I am going to try, because the sockets only cost about 3 dollars each, is to solder a tube directly to a second socket, so it will be even easier to plug into the socket on the board. I hope that is able to be understood. As I do this, I will take pictures and add them to the thread!
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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 13 Jul 2016, 15:30

Good news on the MillMax 8 pin socket setup on the Frog tube preamp PCB. Last night I populated the high and low voltage (heater) portion of the PCB. The socket is soldered in and looks really clean and professional (see the attached pictures). I clipped the leads on the Russian submini 6n17b vacuum tube. I oriented the tube leads per the Frog Tube Preamp documentation on http://frogpedals.com/index.php/product-documentation/ page. It lit up the first time! I need to determine if the connection is robust enough, and I still want to experiment with soldering the Russian submini tube into another MillMax socket. The sockets fit together perfectly and very tight. Next I will work on the audio portion of the preamp PCB. I'll keep you posted. I spent about an hour getting this portion together in part because my work area is a bit disorganized. I also test each resistor and don't rush in general. This is supposed to be fun anyway...why rush? I know I have focused on the submini build approach, but it works great with standard Noval sockets and 12Ax7 and 6nxP Russian preamp tubes!
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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 14 Jul 2016, 15:51

For those that have ordered the Frog Tube Preamp board, please let me know as you receive them. It will make me feel better that you have received them. I need to know about any issues regarding shipping, so feel free to comment or message me. Initial impressions of the board would be great too! A bill of materials (BOM) is included in the documentation and critical parts have part numbers with clickable links to the suggested supplier if you pull it up as a PDF ( http://frogpedals.com/index.php/product-documentation/). They are US targeted suppliers. Of course there are quite a few boards headed to Europe right now including: Sweden, UK, Czech Republic, France, Spain, Germany. If someone would like to document the best suppliers in Europe for the more critical parts, I would be glad to add an addendum to the documentation for those in Europe, or for any part of the world! The part I had to experiment with the most was the 100uH inductor. There are so many different types, and I had to get the right one to fit on the board. Size of capacitors can be an issue too. Most of the prototyping I did was moving things around so they had room on the board! I thank all of you for your PCB orders. I can't wait to put a pin on the Frog Maps (http://frogpedals.com/index.php/frog-maps/ in almost every country!
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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 18 Jul 2016, 02:58

Though this post focuses on a Russian submini tube implementation of the Frog tube preamp circuit board, remember that it can be used (and probably much easier) with a 12ax7/ECC8x tube. I am just intrigued with submini vacuum tubes right now. If you follow this thread, on my previous post I was installing a MillMax transistor socket onto the circuit board. It holds the leads of a submini tube quite well, however for gigging it may not be too robust. A soldered in submini tube would be the most robust but least flexible solution. So what if I soldered a submini tube into a MillMax socket and then plugged in the socketed tube into the board mounted MillMax socket? It works fantastically! This will give me the robustness needed and flexibility I want. The red silicone is automotive type with heat tolerance up to 260C/500F constant. The tube is rated at up to about 180C/370F. It will insulate the MillMax socket and add to its robustness. Only a fine tip soldering iron will do! I cut the leads to 5mm/ 3/16inch. Boards are 10 dollars US plus shipping till August 6th then go to 14 dollars US (http://frogpedals.com)
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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 19 Jul 2016, 16:26

One thing I have noticed is that the Frog tube preamp has a lot of output. The board mounted volume pot is BEFORE the second tube stage and is somewhat interactive with the bright switch. So, on one of my prototypes, I put a master volume on the output side of the second tube (not included on the PCB) and for some reason, I really like it that way. So, I have the signal going as hot as I want into the second tube stage (though it doesn't seem to overdrive it) and then use the master volume for the overall output. The board mounted volume control is more of a gain control in this configuration, but again, doesn't overdrive the second stage. It is hard to explain, but I hope some of the Frog PCB builders experiment with it. There are so many things that can be done with this board. This could "front-end" any power amp really! The Grateful Dead and Pink Floyd used the Alembic F2b to frontend power amps too!
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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 27 Jul 2016, 15:26

A note about power adapters (wall warts, etc...). I did a little demo video on Facebook a few days ago http://facebook.com/frogpedals and one person from the Netherlands brought up that he heard a hum in the audio while I wasn't playing the guitar. At the time I didn't notice it but I went down the next morning and turned everything on and indeed there was a hum. He recognized it because he has an older Ibanez tube compressor that had the same hum and it drove his sound guy crazy. So, I looked at the wall adapter and it looked pretty old and looked like it was probably for a small appliance of some kind as opposed to an audio power adapter. I am certain that the wall adapter I was using was not regulated and filtered but was just a transformer and rectifier. As you may know, in a tube amp, there is a lot of filtering that should take place after the transformer to keep things quiet in the amplifier. A few weeks earlier, I ordered a few wall adapters for audio use from a pedal parts supplier here in the USA. I opened one of those up and plugged it into my demo setup and it was quiet. In fact I turned the preamplifier volume control up all the way and turned up the amp pretty high and still no hum. I even switched to another preamp prototype I have and it sounded good too. There is some input voltage filtering built into the Frog Tube Preamp PCB, but this just shows that you have to use a wall adapter built for audio use to keep things clean and hum free. I hope this lesson helps you! I am convinced that I need to only use audio grade power adapters! See attached photos. The smaller size wall adapter is the better one. It is even rated at 1.5 amps!
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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 31 Jul 2016, 02:20

Thanks again to Christopher Timko of Kansas City for cleaning up the schematics in the Frog Tube Preamp Documentation. I have uploaded the new 2.0.2 version in the http://frogpedals.com/index.php/product-documentation/ page. It contains a ton of information to help you build the preamp PCB. RIght now it is about 20 pages. There are also some sample drill templates on the product documentation page. Featuring one of my prototype builds in the photo.
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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 01 Aug 2016, 19:37

For only 6 more days, the Frog Tube Preamp DIY PCB is on sale for the discounted rate of US10 dollars plus shipping. After that, it goes to US14 dollars plus shipping. I just sent PCBs to New York and sunny Florida. To order go to http://frogpedals.com. Its time to jump on this deal! You miss 100% of the shots you don't take - Wayne Gretzky
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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 05 Aug 2016, 16:22

It is approaching about a month since I started shipping Frog Tube Preamp PCB's to people in the USA, Canada, U.K, Sweden, France, Germany, Spain, Czech Republic and Australia. I know some people said they received theirs, but had other projects in the way, but certainly there are a few people that have begun building their PCBs. If so, let us know how it is going, if you are having component sourcing problems or any other problems. Of course if things are going well, then let us know that too! Eventually, we need some build reports with pictures, etc. I have built quite a few and each one is a little different so I imagine there are an infinite number of ways to do things. Below are pictures of a few different ways I have completed my PCB's. http://frogpedals.com

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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 11 Aug 2016, 16:21

Though this forum has been quiet, things have been hopping at frogpedals.com. This week, I have sent two prototype boards to fabrication. One is my updated Jfet Pre/Buffer designed to be mounted onboard for my Cubist guitar I have designed. The Jfet pre/buffer is based on a modded Tillman Jfet preamp/buffer. It is a 1inch x 1inch board. The thread for that is here: viewtopic.php?f=16&t=27804 . Another thing I am excited about is the Frog Tube Preamp PCB with no power supply built onboard. Why would I do that? Well, some of you may want to build a 2 channel preamp based on the Alembic F2b. Because the high voltage SMPS power supply has plenty of power (20ma) you can run a second (maybe a third...) preamp channel from the power supply of the original Frog Tube Preamp 2.0 DIY PCB. The board is a little narrower as well, so I have tried to conserve as much space as possible, but still give full preamp functionality. I left the regulator for the 6 VDC heater circuit onboard. I also am working on two, stand-alone power supplies. One is the SMPS high voltage power supply that was on the original Frog Tube Preamp PCB 2.0. It is a real small form factor board at about 1inch x 1.5inches still providing up to 190VDC. I am also working on a "classic" tube amp transformer based power supply. It will use a high quality flatpack transformer with rectifier, capacitor, resistor, capacitor layout. It will be very much like any tube amplifier power supply but on a PCB with a step up transformer so you can use 9-12VAC wall adapter. It will provide between 20ma and 50ma at 215VDC to 260VDC, depending on the transformer model used. Right now, the size of the PCB is about 2.25inches x 3.5inches (no pictures yet). I am trying also to keep it 1 inch or less thick. I am trying to keep it as small as practical. I will be testing the function of the classic power supply as soon as I get the Frog Tube Preamp 2.1 with no power supply back from fabrication in a few weeks. NOTE: The Frog Tube Preamp 2.1 PCB with no power supply has the Russian submini solderable socket as well and it has now been "MillMax'ed". you will see in the picture below that the holes are evenly spaced and made ready for a MillMax socket (see earlier thread) but can still be used if you choose to solder in a Russian submini tube!
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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby rbstep » 12 Aug 2016, 13:31

Looking forward to these projects...
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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 15 Aug 2016, 16:55

To follow up my earlier post regarding a "classic" power supply for tube preamps....or low wattage preamp/power amp (wink). Here are a few pictures of my raw prototype and current design of the future PCB. The photo shows the power supply lit up with 9VAC with no load providing 221VDC. Under load I estimate the voltage would drop to 205VDC. I will test with 12VAC input later. That will increase the voltage output by a bit. This is in a package about 2.1 inches by 4 inches by less than 1 inch thick. All this is untested under load until I get the Frog Tube Preamp with no power supply PCB back in a few weeks. There are a few reasons I would want to use this power supply but mainly, if I want to commercially make completed preamps (or low watt practice amp...wink again...) and not have to pay the fees for FCC certification, then I can use this power supply. It is much bigger than my SMPS for the Frog Tube Preamp, but, it will save the 3000 dollar certification fee. Maybe later I can afford the cost of certification. Let me know what you think! I will talk about some of the specific design features of the Frog Classic power supply later. Though I have some commercial building plans, this power supply and all the other boards, once tested and fabricated will be made available to you via http://frogpedals.com
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