Frequently Asked Questions with Mickey

Q:	Can you provide a schematic for London Power's power scaling?
A:	It can be found in the series The Ultimate Tone, by Kevin O'Connor. Your best course of action is to start at London Power / Power Press . The schematic for Power Scaling the 18 watt 1974X (and clones) is here. This is free for DIY non-commercial use only.
Q:	What is the actual schematic used for my Londoner 18 watt amplifier?
A:	It can be found right here:  Londoner 18 schematic
Q:	Did you post a 20 watt clone Lead & Bass Schematic and Layout?
A:	Sure did, here's the 2061X Lead & Bass Schematic, and here's The 2061X Layout . We'll be offering a kit of this amp soon! I posted these on a few online forums I frequent, however it's since come to my attention that somebody has already ripped off my credit, and is floating these around the internet without my name on them. Shame on you - it was a LOT of work to make them, and I don't mind them being shared with the world, but NOT with my artist's credit & Soultone Copyright removed. Please destroy the documents, and only circulate these. Better still, put a link to these so when there's updates, you can get the latest greatest circulated. The rest of you - sorry for the rant, and enjoy! I'll have a 20wattamp forum up soon for those of you interested in building clones of this fine amp! Thanks! - Mickey
Q:	On the Londoner Combo, how do I remove the chassis?
A:	We would rather that you didn't. If you are after a view inside, we can provide you pictures of your very amp. We have them all on file. However, if you feel you must, do as follows: With the unit plugged into a wall outlet, leave powered off for 30 minutes (drain internal capacitors). Unplug the power cable, first from the wall, then from the amplifier Lay the amp face down on a soft surface (like carpet) Disconnect the speaker from the speaker output jack Remove the four outside screws holding the upper back panel to the cabinet. Lift the entire assembly out of the amp, and  set on a soft surface. Now, remove the inner screws on the back panel - these actually attach the panel to the amplifier chassis. Don't touch anything - there could be lethal voltages present. Reverse this order to reassemble the amplifier.
Q:	Why does the Londoner tremolo channel exhibit such sensitivity to tube types?
A:	It's the design implementation of the oscillator circuit designed by Marshall. While we have certainly quieted it up a bit, we have not modified it from the original 18 watt Marshall design. We recommend using a Groove Tubes 12AX7WA, or a JANGE 5751. If you feel it is overly sensitive, contact us, and we will either help you resolve it, or give you an RMA to get it back here for service.
Q:	Why does exclusively use Mercury Magnetics Transformers?
A:	They are simply the best sounding transformers currently available. By special order we can use some of the other variants, including the excellent sounding sets from Heyboer. Our top choice is Mercury!
Q:	Which speaker output jack should be used with the internal speaker?
A:	On any Soultone amplifier, the speaker jack closest to the impedance selector should always be connected.
Q:	I thought my speaker(s) would  be a Celestion G12H30, and it says "Hellatone 30" instead. What's the deal?
A:	The Hellatone 30, by Avatar speakers, is in fact an aged Celestion G12H30. If you look on the outside rim of the speaker magnet, you will find the actual celestion label. The aged speaker provides you with a better tone from day one; it's an excellent match for the Londoner 18. If you really want it to say "Celestion" the Hellatone label easily peels off. However, it's worth less as a plain old, non-aged, Celestion.
Q:	You state the Forty-Five amplifier contains some form of power attenuation... could you be more specific?
A:	By special arrangment London Power, Ltd., inventors of the technology called "Power Scaling", the Forty-Five is indeed a Power Scaling amplifier. The amp utilizes many innovations championed by Kevin O'Connor of London Power/Power Press, and author of the acclaimed "The Ultimate Tone" series of books on tube amplifier design. Soultone, with the assistance of London Power, has developed its own Power Scaling boards, and does not incoporate the Power Scaling Kits that Kevin Sells. For this reason, he listed Soultone as "Variable Power", but it is in fact Power Scaling.
Q.	The Forty-Five information states that you can use a number of different octal power tubes. I have read contrary information about using different output tubes in a power amplification section. What's the concern?
A.	Sure, we've all heard these disccusions before - there is much controversy regarding reflected loads from the speakers to the output transformer primary, and impedance matching of the output tubes. The concern is that some tubes may see a reflected load less than their "optimal" primary impedance. The unfortunate confusion is because people tend to think of tubes as linear devices, which they are not. Transistors would attempt to deliver twice the current into one-half the load. Tubes, in simple terms do not. In fact, they will simply deliver the same power output (determined by their voltages), with a higher Total Harmonic Distortion. Output transformers convert high-voltage low-current swings from tubes to low-voltage high-current swings for speakers. Reflected loads are seen by the amplifier section, not the speaker, so there is no concern going the other direction, and as stated above, the net result to the tubes is merely higher THD. Also, remember that speakers are reactive devices - so transformer primary impedances are always nominal - meaning the fact is they are indeed varying as the impedance of the speaker is varying with different frequencies. The original application of tubes for power amplifiers was very concerned about THD being of a low-order - remember these were used for Hi-Fi, Avionics Radios, commercial broadcast, and a number of other applications where THD would make the signal unintelligible. Conversely, tubes are admired and used (nearly exclusively for this reason) by guitar players for their THD characteristics. So don't worry about the THD - power dissipation (for the power bandwidth) in sum is unchanged. In fact many of us want to explore and experiment with the varying distortion made available in this fashion. The real concern to be mindful of in swapping tubes is A)the power transformer is not delivering more than the maximum specified voltages, B)the bias has a range capable of handling the different tubes, and C)the filament supply has enough current for the different tube types. A further design consideration is, if all the above is true, the amplifier should have the capability to provide independant bias adjustments for running different tube types. All of these engineering constraints have been properly applied to the Forty-Five.
Q:	Can I purchase a Soultone kit?
A:	YES! See the pricing page, we are now offering kits of the 2061X amp. The production Londoner 18 or Revolution 45 is only available as a finished product. Occassionally we also have discontinued versions of product parts available. Contact us to find out if there are some surplus items available. A JTM-45 kit can be purchased from Metroamps.
Q:	What's the lead time for a custom ordered amp?
A:	Quality takes time. Contact us, and we'll let you know what the current lead time is.
Q:	I purchased a Soultone Amp used - can I get it covered by warranty?
A:	That's a difficult question, and may even be complicated by laws in your state. Contact me, and let's discuss it on an individual basis.