Frog Tube Preamp Inspired by Alembic F2b

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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 19 Sep 2016, 17:24

Comment by Wavley:
"I'm really in to getting the preamp, classic power supply, and output! Sounds like they'll make really cool tiny tube amps that you can shove in nearly anything."

Thanks Wavley, hang in there and I will be able to better define what is needed and then what you get out of them, specifically in regard to the output section. The preamp I have been using for about a year, and I know what it can do, I have the prototype power supply boards (the actual purple PCB type) and have a new stronger transformer on order so I can test the PCB (as opposed to my version on perfboard). And I know the Bigmouth output works as well. I think the stronger transformer for the classic power supply will make that configuration shine. When you go with the classic power supply, you have to go with a little larger enclosure though. That is why I still want to try and work out a output configuration that will use the small SMPS albeit with lower output wattage for those that want to keep the smaller footprint.

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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 23 Sep 2016, 16:43

I am excited that I received the new, slightly bigger/stronger Triad flat-pack transformer model for my prototype "Classic" tube power supply. I was relieved that it dropped right into the holes on my prototype PCB. So this weekend, I plan to test how robust it is when running the Bigmouth output section. I should have 2.5 times greater power capability with this version of transformer http://catalog.triadmagnetics.com/item/ ... fp24-250-1 compared to the first one I purchased (FP 24-100). It will still be around 1 inch (25mm) or less thick overall depending on the size of the capacitors and on a 3.89x2.10 inches (98.76x53.34 mm) PCB. Believe it or not, the cost of the transformer is within a dollar or so of the previous transformer. Despite the compactness of the power supply, it puts the size of the enclosure when you include the Frog Tube Preamp and Bigmouth output section into the 1590DD range. Of course, this would be a small tube amp, not a guitar pedal, so even building your own sheet metal enclosure is possible approach.
http://frogpedals.com
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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 29 Sep 2016, 17:17

I just wanted to give a bit of an update on the Frog Bigmouth output board being used with the Frog "Classic" power supply. I found another 12VAC wall transformer and was able to continue testing. I was able to get 1.7 to 1.8 watts output using a 12AU7 or a 12BH7A tube, running at 170VDC to 197VDC out of the "Classic" power supply. It actually can get quite loud when hooked up to my Celestion 75 12 inch speaker. The volume is totally controlled by the volume control on the Frog Tube Preamp.

Of course when running at higher volumes you have a nice creamy overdrive to a very strong overdrive sound. At lower volumes it cleans up pretty good. The preamp/output is very reactive to the type of pickup you are using. With a humbucker, you overdrive much sooner than a single coil pickup.

So, the "Classic" power supply is a success and the Frog Bigmouth output board is a success. I do need to get one put in an enclosure instead of testing it splayed all over my bench (see picture below). I want to go back to the Frog SMPS power supply which is much smaller and see what I can do to beef that up to decrease the overall size of enclosure required for the Frog Bigmouth. Otherwise, I think the Frog Bigmouth and Frog "Classic" power supply are ready to go.

How many of you are interested in and would buy a 1 - 2 watt output PCB with the "Classic" power supply? I have no idea how many to order for sale. How many would prefer to wait to see if I am able to create a small SMPS that can keep up with the power needs of the Frog Bigmouth? http://frogpedals.com
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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby rbstep » 30 Sep 2016, 02:00

I'm in for the classic power
supply...

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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 30 Sep 2016, 15:36

I think I am going to go one more iteration on the Frog "Classic" power supply. Triad has another slightly bigger flatpack style transformer, but it can handle even more power. For some reason at Mouser.com, it is a dollar or so cheaper than the -250. Maybe it is a bit more popular.... So, I am going to redesign the PCB to handle both the FP24-250 and FP24-500 models. The -500 has a wider pin spacing and is wider in general, so, the PCB will probably be a bit bigger but not by too much. I am sorry for all the testing and redesigns, I just want to feel as confident as possible with the final product. There might be a slight update or two to the Frog Bigmouth PCB as well. I will keep you informed.

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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby rbstep » 01 Oct 2016, 20:04

I have at least 4 projects I can use the classic PSU board with.
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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 02 Oct 2016, 02:04

rbstep wrote:I have at least 4 projects I can use the classic PSU board with.
Keep in mind: WIth the Triad FP24-250. Under a load that is running 13ma, it draws the high voltage down to about 170VDC. At 10.5 ma, it is about 182VDC and about about 8.2ma, it is around 200VDC. So, depending on the load, your voltage will pull down.

Keep in mind, that this power supply can provide over 200VDC for 2 or 3 preamps, and about 200VDC for a 12AU7 at 1 Watt, or 182VDC for a 12AU7 at 1.8 watts, or about 170VDC for a 12AU7 at about 2.5 watts. What I am getting at is that you really need to determine the load you will be putting on the PSU and what your load in milliamps and VDC requirements will be.

I am preparing to modify a PSU board design to handle the FP24-500 transformer which is quite a bit larger and can handle about twice the load. I may keep this current PSU board as an option, we will see. One of the problems I am running into is that I am already running into a maximum board length for my license of the board design software. And upgrading the software is expensive, so, I may have to keep the length the same and fatten the boards width to get the FP24-500. I am going to try it, but it will be starting to get large.

Currently the board size is 3.89 inches by 2.1, but for the bigger transformer, we are getting up to 2.5 or 2.75 by 3.9 inches. Doesn't sound like much, especially if you are going to go with a larger enclosure, but to keep it within a standard Hammond 1590XX enclosure, it is getting too big! Despite the board not being extremely complicated, because of its size, it will probably be the most expensive board to fabricate so far... http://frogpedals.com
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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby rbstep » 02 Oct 2016, 22:17

I got You. Enclosure size is not my concern. Will do the frog with nixie PSU for pedal build and larger enclosures for the others...all is flexible right now...

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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 03 Oct 2016, 02:18

One thing that was illustrated to me when I was testing the milliamps draw and voltage from the Classic Power supply, was that you can very easily have the output wattage select-able from 1 watt, 1.8 and 2.5 watts. When configuring the Bigmouth output section, the default cathode bias resistor I used was 1500 ohms. That gave me 1 watt output. So, instead of unsoldering the bias resistor, I used alligator clip jumpers and clipped another 1500 ohm resistor parallel with the soldered-in resistor.

If you are familiar with parallel resistor calculators, you will find that 1500 ohms in parallel with 1500 ohms, gives you 750 ohms, so with that clipped in, I was able to test output with 750 ohms of cathode bias and got about 1.8 watts output. So for fun, I added another 1500 ohms resistor to the alligator clips and paralleled that with the soldered in 1500 ohms, you get (1500 / 3) 500 ohms and netted 2.5 watts output, which is about the max for a 12AU7 tube. So, I was thinking, you could switch in parallel resistors based on the amount of output you desire.

There might also be some tonal characteristics that are different per setting, and you CAN switch on the fly. I haven't tested the specific tonal aspects, but of course, you can definitely hear, as you clip in the additional resistors, the volume increases. If you don't care and want it permanently set, you could solder in the resistor of your choice. I will not recommend less than 500 ohms. I need to start getting the documentation started! http://frogpedals.com

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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 03 Oct 2016, 16:48

I will be placing an order for the Frog Bigmouth PCBs and Frog "Classic" power supply PCB's this week. So hopefully by the end of October, I can make those available. I have a lot of documentation to get ready! Not to mention the Frog Tube Preamp 2.1 (add-on channel) is due in any time.

This weekend, I played around with the Frog Bigmouth output section with the Frog Tube preamp running into it and I am really liking it. There is quite a range of sound from the different pickups on my guitar, as well as the EQ on the preamp really effecting it. Now to get it put in an enclosure! http://frogpedals.com
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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 17 Oct 2016, 04:13

Got some feedback from someone building the Frog Tube Preamp on the madbeanpedals.com http://www.madbeanpedals.com/forum/index.php?topic=23234.msg234779#msg234779

Sent a few Frog Tube Preamp 2.0 PCBs to Ross S. in Philadelphia, PA USA ! Thanks Ross!
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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 19 Oct 2016, 02:44

Just a note to all of those that may be waiting on the Frog Tube Preamp 2.1 PCB add-on channel. I received the boards from the fabricator, but the component labels were not printed on the boards (see attached picture), so, you wouldn't know if a resistor was R1, R2, or capacitor was C14 or etc.....so, I am contacting the fabricator which is in Hong Kong and will work on possibly placing another order. They look fantastic, Black with gold solder pads....other than the component labels. I am sorry. I didn't see this one coming. If you are wanting to make a two channel, you can use two of the 2.0 boards and only populate the high voltage power supply section on one of them and connect the two B+ test points together. Of course you need to share a ground between the boards too. I suggest you run the low voltage regulator for the heaters on each board though. That will lower the load on the regulator for longevity. I can help anyone that is interested in that approach in the mean time. http://frogpedals.com

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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 21 Oct 2016, 15:23

Just an update on the Classic Power Supply and the output section. I have not placed an order yet. With the add-on channel preamp having a fabrication issue and needing a little more cash to produce more boards and life just happening at a fast pace right now, I have had to delay the order, but it will be coming soon. So, I apologize for the delays. I am confident in the Classic power supply right now, so I don't anticipate more changes. A few more updates on the Bigmouth output section are possible before I order, because I asked a friend of mine, an electronic engineer, to test my prototype PCB out and I want to see if he has any constructive criticism of it before I order. I am mostly using his design (the paraphrase split output), so I want to listen to him. I will supply documentation (haven't got much of that done yet) to have three output power settings, which will kinda be like having a bedroom, recording and small gig setting! Keep in mind, you can mic it through a PA system and it can sound as big as you like.

Thanks for your patience,
Mark
http://frogpedals.com

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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 27 Oct 2016, 20:22

As you may have read in my earlier post, there is a minor problem with the Frog Tube Preamp 2.1 add-on board (with no onboard power supply) that recently came back from fabrication. For the capacitors, resistors and diodes, there is no label. So, there is a resistor image, but no R1, R2, etc. and so on for the other components. Though that is inconvenient, it can be easily overcome by looking at a diagram that has the labels on it. I was considering selling the board for half what I originally was planning, which would be 5 dollars. Standard shipping rates apply. For the basic shipping rate, you could get easily get multiple boards in the shipping envelope.

Does that sound something you would like, despite the error? Please let me know your thoughts.

I will put the board back up on the website: http://frogpedals.com this evening, if you wish to purchase it.

You could build this stand alone, but you need a high DC voltage (~190VDC) power source. It can be run off of the Frog Tube Preamp 2.0 by taking power off of it. Below is a diagram that illustrates that (see below). I recommend you mount the potentiometers and switches off-board because the tube is very close to the pots. I will finish the documentation this coming weekend. I have already started it, so I don't think I will have much more documentation to do.

I am still working on two possible separate power supplies, a small SMPS which is the same high voltage power supply built into the Frog Tube Preamp 2.0, just on a separate PCB and the Classic power supply. Those have not gone to fabrication yet because of the fabrication problem I had on this board, so those should go to fabrication within the next few weeks, so my new target timeframe.

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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby theehman » 28 Oct 2016, 14:04

I'm ok with it as long as there's decent documentation.
Ron Neely II
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fx schematics and repairs

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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 28 Oct 2016, 18:54

I have added the Frog Tube Preamp 2.1 add-on board (no powersupply) on http://frogpedals.com. It will remain at the sale price of 5.00. I will post the product documentation by 10/31/2016 on the Product Documentation page. If you have any questions, please let me know! Thank you for your interest.
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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 03 Nov 2016, 02:24

Sending a total of 5 PCBs out today. 2 to Bloomington, Indiana, 2 to Melbourne Victoria, Australia and 1 to Matton, France. Thank you to Ron, Ben and Emmanuel! I look forward to seeing your builds. Let me know if you have any questions! Thanks
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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 05 Nov 2016, 03:46

Another 4 Frog Tube Preamp 2.1 Add-on PCBs to Wavely in Staunton, Virginia! Thank you!
Can't wait to see your project pictures and comments!
http://Frogpedals.com
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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 07 Nov 2016, 00:40

There is an update to the Frog Tube Preamp 2.0 and 2.1 Add-on version documentation. Some Mouser.com part numbers were not correct and I am sorry for that. Timko found a part number for a 22nf capacitor pointed to a 220nf capacitor at Mouser. Also an updated part number reference to a better Heat Sink. SO. DOWNLOAD THE UPDATED VERSIONS. For the 2.0 board, download the 2.0.3 documentation. For the 2.1 Add-on board download the 2.12 version at http://frogpedals.com/index.php/product-documentation/
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Re: Frog Tube Preamp Inspired by Alembic F2b

Postby mark.price » 08 Nov 2016, 01:54

4 new PCBs going out today. A Frog Tube Preamp 2.0 and 2.1 add-on board to Hardinexveld-Giessendam Netherlands. Thanks Siemens and Frog Tube Preamp 2.0 and 2.1 add-on board to Francis in Ille Surtet, France. Thanks.

Be sure to download the updated documentation. I am still trying to find a better heatsink part number too. Frogpedals.com
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