Stand-alone tube preamps

[megatrav]

Hi!

I apologize in advance for the lengthy post..

Around 2015 I picked up a really cool preamp pedal made by Kingsley Amps in Canada. I happen to have his Squire D, which is based on the Dumble ODS clean channel.
Sadly, I had to sell the pedal because of financial trouble.
Fast forward to 2018, I was on a waiting list for over a year and eventually took myself off of it.

I know that there are some companies out there that make pre-amps of amps and some are based on actual preamp circuits of amps, but I was wondering if anyone on here has done built one before? I did find someone who has a Fender Blackface stand alone pre-amp, but its not exactly pedalboard friendly like the Kingsley was.

https://www.ebay.com/itm/173666228793?ul_noapp=true This is that unit.

This is the inside of the Kingsley Maiden

This is the inside of the Kingsley Squire.

I'm not looking to clone this, but essentially build just the preamp section of an amp.

It is fairly simple to do?
Could a novice do it?
Could someone build one for me?

I appreciate any feed back!

[martin manning]

Kingsley pedals seem to be pretty scarce. It's a shame he won't increase his production capacity to meet demand. In any case, a novice could easily build something like a Squire D from a kit, but reverse engineering it would be a much bigger challenge. What he has done is modularize the D, BFFender and AC30 TB (Rocket to Trainwreck fans) preamps using a modern switch mode power supply so as to fit them into a pedal-sized box and run them from 9VDC. He's certainly done some tweaking to get them dialed in, so one could expect to do the same if a copy were to be made. Best you could hope for is that someone has traced out the circuit. There is a very nice gut shot here: http://kingsleyamplifiers.com/staticmed ... report.pdf

The images didn’t make it into your post above.

[megatrav]

Yeah, I definitely don’t want a clone of his work.
Even something like the eBay ad I posted would be fine.

There is also a company called Baroni Lab that have a few models for preamps- Hiwatt, Fender, Vox, Mesa, etc.

https://www.baroni-lab.eu/pedals/

I wouldn’t mind trying to build a stand alone unit from a kit, but I haven’t been able to find a kit for just preamp sections of an amp.
That’s why I came here. To see if anyone else might know or someone on here might be interested in building one.

[sluckey]

LooseChange (Dan Lurie) builds some nice preamps. He's a member here and over at Hoffman's forum. He's in the business, not just a hobbyist.

[didit]

Hello -

Noticed while back KOC @ londonpower.com had a D-style preamp PCB + kit (and others too). Not in pedal form-factor but still standalone.

Best .. Ian

[tubeswell]

After a saw Steve Luckey's one on Hoffman forum a few years back, I did my own version of a stand alone pitch-shifting vibrato unit (that goes in front of an amp like a stand alone reverb). Uses a saturable reactor from a Hammond AO47 organ vibrato - Again not a pedal, but it footswitchable.

Still got it.

Some funky spacey sounds, as well as bitchin' low-down'n'dirty sustain when the vibrato is switched off.

[megatrav]

Very cool!
Is there a site or way to check out what they have?

[pompeiisneaks]

Very cool!
Is there a site or way to check out what they have?

Do you mean something like this:

http://sluckeyamps.com/warbler/warbler.htm

~Phil

[martin manning]

Isn't the subject here compact (i.e. pedalboard friendly) stand-alone preamps, as opposed to tube FX like the Revibe?

There have been several tube preamp "pedals" marketed, including the recent EH English Muffin, which is an entire Marshall preamp in pedal format. That one uses a transformer based power supply with 12 VAC input rather than SMPS, but it is compact for a device using two noval tubes. Hoffman has a tube preamp design too, which uses the same type of power supply as the EH unit. See "Tube Pre Amp in a Pedal Box" project here: https://el34world.com/schematics.htm#Tu ... pedal_box_ Reconfiguring that unit into a D-style preamp wouldn't be difficult.

[M Fowler]

Build your own in compact metal enclosure using small PT, good filtering and your choice of clean Fender tone stack or add in higher gain stuff.

I run my tube preamp into a Class D 600w Sure power amp.

Mark

23172681_10209779357472226_6446156116731051329_n.jpg

[megatrav]

Hey all!

I wanted to post back and say that I found a guy on ebay to build me a tube preamp pedal. He let me pick whatever design I wanted, so I found a schematic on here for the Two Rock John Mayer signature amp, so he is building it based off of that.
His preamps run two 12ax7 and he making the mid boost feature on the amp foot-switchable.

My biggest issue is that it is being built to take a plug style power supply, which will make adding it a pedalboard a tad more difficult.

For you builder guys out there, is there a way to convert to a 9,12,or 18 volt power supply? A lot of people are building tube pedals running on high voltages and then converting them back down to 9, 12, or 18 volts.
If there is a schematic for this, please share. I will be able to send it to him and see if he is able to do it.

I imagine there is a way to do it if pedals are being built this way, so any input would be awesome.
That way, I won't have to mount a power conditioner strip to my board and just use the pedal power supply I have (has a lot of options for 9 volt at different MA, one 12 volt, and one 18 volt)

Thanks and Happy New Year!

[frankdrebin]

if you use 2x12ax7 at 12V it means you need 300 mA for filaments and another 100/150 mA for the SMPS that feeds the HV,i personally use a separate 12V/2A power supply for security,just in case something goes wrong it won't mess any other circuit.

[vachterm]

Hey all!

I wanted to post back and say that I found a guy on ebay to build me a tube preamp pedal. He let me pick whatever design I wanted, so I found a schematic on here for the Two Rock John Mayer signature amp, so he is building it based off of that.
His preamps run two 12ax7 and he making the mid boost feature on the amp foot-switchable.

My biggest issue is that it is being built to take a plug style power supply, which will make adding it a pedalboard a tad more difficult.

For you builder guys out there, is there a way to convert to a 9,12,or 18 volt power supply? A lot of people are building tube pedals running on high voltages and then converting them back down to 9, 12, or 18 volts.
If there is a schematic for this, please share. I will be able to send it to him and see if he is able to do it.

I imagine there is a way to do it if pedals are being built this way, so any input would be awesome.
That way, I won't have to mount a power conditioner strip to my board and just use the pedal power supply I have (has a lot of options for 9 volt at different MA, one 12 volt, and one 18 volt)

Thanks and Happy New Year!

Afaik kingsley used "step down" transformers wired "in reverse" - primaries as secondaries and vice versa.
So, instead of supplying 220v in (imagine youre in europe) and getting 12v out, you'd supply 12v in and get 220v out (excuse my technical english- it is not my main language).
iirc, earlier versions of his pedals used amveco 62010 transformers wired "in reverse".
If anything has changed in more recent versions is unknown to me.

[martin manning]

That’s the route I suggested above, referring to the EH English Muffin and Hoffman circuits, That requires a 12VAC power source, not commonly available on pedal boards (see below). Kingsley may have done that at some point too, but the Tone Report article photos show a small PCB with a SMPS, and the description here http://kingsleyamplifiers.com/products/pedals/20/ specifies 12VDC, 500 mA from a wall adapter. My guess is he's now using a regulated 12VDC SMPS adapter, which powers the filaments directly and eliminates the need for a filament supply in the pedal. Such things are now readily available and cheap (CCTV power adapter). For the HV supply, I think he's using something very close to this: https://www.instructables.com/id/Adjust ... i/#discuss

[JoeTele]

I'm finalizing plans to build a Fender BF preamp (single 12ax7 only) in a pedal and was thinking of doing the following. 12v/500ma (or perhaps 1a for extra safety) AC wall wart into a 115v/6.3v filament transformer run in reverse (xfmr rated for 300ma on the secondary and total power of 1 volt amp). The 12v in would power the filaments directly (wired in DC) and the filament transformer would only supply the high voltage. Is this a sound option? If so, with no 3-prong set-up should the chassis still serve as ground for the circuit?

Otherwise, I may just use a TubeDepot "Button" transformer that is a step up from the mains and is designed for a single tube. That would be the most familiar for me.

Thanks as always!

Joe