London Power ad

Kits & Books

Search the Forum

(Advanced Search)

  New kid
Posted by: FormyxAmps - 05-21-2019, 05:26 PM - Forum: New Member Introductions - No Replies

Hi all,

I am a 40-yr-old youngster who builds tube amps and repairs/renovates instrument and Hi-Fi amps. Started reading the TUT series and building amps as a hobby, aside from guitar playing with our band, at around 2007-8.

After messing around, building, repairing and reading trying to figure out how stuff work, I decided that life is not worth it if you don't do what you love, so last year I decided to give it a go and launched my small company in Stockholm, SE in the hope that someday I won't have to be employed at my boring day job any more...

Very glad to be here in the forum with you all! Hope to contribute however I can! Smile


Print this item

  Question about Applying SUS-2 to See-saw Inverter
Posted by: makinrose - 05-05-2019, 01:19 AM - Forum: Sag & Sustain - Replies (6)

I'm working on designing a new amp.  I've used SUS kits before and really like them but have question: When applying the SUS-2 kit to cathode bias amp with the "Old Style" See-saw Inverter is it okay to lift the grid-leak connections to ground even though one of the triodes is sending signal to the other?  Will this affect the operation of the phase inverter?  Here's link to style of inverter:  Huh

Print this item

Video Londonpower PSU-20L, BFX, L-Pre, Z-Pre, Line-Out Pre amplifier
Posted by: peteotto - 04-26-2019, 09:50 PM - Forum: Personal Projects - No Replies

Print this item

  Heat management with Power Scaling??
Posted by: makinrose - 04-02-2019, 08:06 PM - Forum: Power Scaling - Replies (1)

With Power Scaling when is additional heat sinking and/or a fan necessary? Is there a certain temperature at which one should worry? I'm guessing chassis up in the cabinet designs are more problematic that the typical Marshall configuration.

Print this item

  New PSU kits +/-12V
Posted by: K O'Connor - 03-15-2019, 05:19 PM - Forum: London Power Kits & Mods - No Replies

Hi Guys

We have two new power supply kits to support low-voltage circuitry, such as for switching and opamps. The kits provide symmetric voltage outputs aka "split rails" of +/-12Vdc at two different power levels.

PM12-6 provides +/-12V at 175mA

PM12-12 provides +/-12V at 350mA.

PM12 has universal mains fusing, and uses Hammond semi-toroidal PTs, metal-film resistrs, and 10,000-hour caps.

Print this item

  Reverb Feedback Issues SOLVED
Posted by: makinrose - 03-12-2019, 12:07 AM - Forum: Personal Projects - Replies (9)

I've been having problem with new build. It's essentially a Deluxe Reverb Combo but with some added decoupling and improved grounding. The issue I'm having is with the reverb tank.  Outside of the combo the reverb is quiet and operates as it should. When placed inside the combo the reverb starts to feedback building into loud howling.  Moving the tank around, flipping is orientation,  and padding the reverb bag really hasn't helped at all. I've tried a few different tanks and am at my wits end about what I'm doing wrong.  Huh  Any ideas?  Thanks for everyone's help!

Print this item

  ToT + Resonance
Posted by: sinusoids - 03-10-2019, 08:48 PM - Forum: TUT Q&A - Replies (7)

I'm now in the planning stages of building a new amp head from scratch.  Plenty of chassis room to work with.  This will be my first LPSP,  I am looking forward to that.  Plan now is the to build the power supply, PA and preamp from ToT but with eyelet cards. 

"thunderous smooth" described in TUT caught my attention - I do not like bright tones or hard distortion.  Would the Active resonance presence circuit, fig 6-34 of TUT, work well in the ToT PA?  I'd use both 12AX7 tubes in the EQ network shown.  Would it work following C1 of the PA, fig 6-2 of ToT, with an added coupling cap?  0.47u?  Would a a larger OPT be a little smoother than the 1608 in the circuit?  I have a single 6lb 6.6k OPT that I could use.  6V6, 5881, 6Pi3C-E and 6L6 all are to be tried.  I will add a triode/pentode switch.  I plan to use the bias supply as described in ToT . 

I want to lay out the circuit cards and build this up from scratch.   I mostly play rhythm, the other guitarist I play with has a bright setup and I try to keep things lower (tone wise) and slightly clean to over-driven.  P-90s are on the guitar.

Thanks for any input from anyone, anywhere here.

Print this item

  power supply to separate box
Posted by: TiCatFan - 03-08-2019, 03:39 PM - Forum: Power Supplies - Replies (3)


I am contemplating putting preamps in a separate box from the power amp and power supply in a unit I am currently building. I was wondering if this is possible or safe? Are there any special types of connectors that would work really will for this? Anything I should consider for the wiring between the boxes? My concerns are about the plate voltages and heaters. The power supply is the PSU-25.


Print this item

  Pots! What brands are good?
Posted by: makinrose - 02-25-2019, 04:53 PM - Forum: Wiring - Replies (7)

What brands of pots do you guys use?  I lots of builder seem to favor the old style CTS pots but I've been using Alpha with no complaints for years.  There a lot of good prices on pots on AliExpress but I'm not sure of the quality. Does anyone have any experience with those brands? Thanks guys!

Print this item

  New member
Posted by: sinusoids - 02-14-2019, 12:55 PM - Forum: New Member Introductions - Replies (2)

After all these years, reading the books, I have joined the forum.  I have built several of the TUT amps, modded more, installed SV1 and 2 and bias kits and built a couple of audio amps (PP and SE) based on and from POP.  Also have read (and built a few projects from) glass audio, audioxpress and VTV.  And I really enjoy this as a hobby.  

Presently building the ToT amp on 2 chassis to enable easy, easy mod and experimentation.  Power supply and PA on the bottom chassis and the pre mounted above, with the hammond chassis cover on top and 12AX7 under.  I also sold my most used combo, bought a 2x12 sealed pine cab on ePay and am loading with 1 driver (taking the idea described in SPKR).  I did not opt for a Force12.  like to hear one in it though.


Print this item

Come in where it's warm!
A warm welcome to those interested in tube and hi-fi audio! Fans of Kevin O'Connor's The Ultimate Tone (TUT) book series form a part of our population. Kevin O'Connor is the creator of the popular Power Scaling methodology for amplifiers.
Please remember these three principles: respect, sharing, community.
Not familiar with The Ultimate Tone book series? See discussion topics, or click here to visit London Power/Power Press Publishing.

Forum Hosted by London Power
London Power logo