London Power Standard Amp

[LooseChange]

I will open this forum up with my tales of building the Standard Amp from TUT5. I built the amp about 1 1/2 years ago and have finally stopped tweaking the thing about two months ago. I have a website that shows all my work.

www.loosechange.freeservers.com

The really neat thing about building this amp and publishing a website is all the people I have worked with from all over the world. Many have contacted me to ask questions and get some help with their build. This has been an extremely rewarding experience.

I do this for fun. Check out the website and feel free to contact me.

[pullshocks]

Thanks for posting your site. I (and I bet a lot of other people) would be curious to hear what you think about the the standard amp, power scaling, and the de-tuned cabinet.

Good tip about pre-wiring and soldering pots and other components before actually putting them in the chassis.

[LooseChange]

The amp is now my main amp when playing with my band. It provides excellent tones for rhythm and lead.
I don't use the powerscaling much but I do use the SAG control. I set it back a bit to get a less punchy sound. This amp has tons of punch.
The detuned cabinet was a great experiment. It may be I don't like the EV Force 15 but the sound is too pristine and it amp fills the room so much it is almost hard to hear it. I built a small 1 x 15 half open back cabinet and loaded it with a Weber Chicago 15. This cab sounds great.

Thanks!

[teleamp]

I built KOC's 1x12 detuned cab for a 6 watt SE amp and loaded it with a G12H and it rocks. Lots of bass response. I could see were too much power would make it boomy, but for low wattage amps its the ticket.

MikeY

[tubelovin]

I like the color of that board, where did you get it?

[LooseChange]

The board material is called phenolic. I found it at a local plastics supplier.

[Tiago]

Where or how did you make the chassis and the faceplates?
They look very nice!!

[LooseChange]

The chassis was all drilled by me on a cheap drill press and a couple of punches. It took about 3 days to do. The faceplates were done at a sign engraver. I gave him a detailed drawing and had them done.
Thanks!

[Tiago]

Thanks!
But you bought the chassis from Hammond?
How did you make that rectangular cut for the AC Power plug?
Just one thing...I dont know what is a "sign engraver" (I live in Portugal and maybe the name is a lot diferent), so can you please describe me what jobs these sign engravers do, and where they usually work?
BTW, how much costed you those faceplates?
Thank you!

[LooseChange]

Yes, I bought the chassis from Hammond. It is basically an open bottom steel box 17" x 10" x 3".
The sign engraver makes those little engraved name tags you see people wear at hotels and stuff. They have a machine that engraves a 2 layer plastic sheet (mine is gold front with black behind). The machine engraves ("scrapes") off the gold layer and revals the black below.

I drilled all the holes in the plastic.

The square hole was done with a "nibbler".
See...
http://www.radioshack.com/product/index.jsp?productId=2289712&cp=&origkw=Nibbler&kw=nibbler&parentPage=search

Are you planning to build a "Standard"??

[Tom Phillips]

Tiaqo,
You can probably find someone at a trophy shop that will be able to do the engraving that Loose Change described.
Hope that helps,
Tom

[Tiago]

OK!
Thanks!
I never saw a nibbler before...yesterday I was considering making the square holes with files...I always knew that the truth was outthere!! I will print the picture and go to the hardware store to see if they got it!

I'm not planning to build the "Standard", even after reading TUT1, 2 and 5, I still have some sanity left...:D
The thing is that when I build an amplifier, the hardest part is getting the chassis work done. I have most of the tools needed, Driil press, stepped drill bits, clamps, jig saw, etc... But even with this tools is difficult and never has a "proffesional" look, like your has. These front panels great!!

I will try to find a trophy shop to see if I can get things done there or at least if they know where I should go.

Once we are here, I will just ask one more thing...
You know that metal grill that some mass produced amps have on the rear and some on the front, like this: http://www.hammondmfg.com/jpeg/1451BK_B.jpg ?
Do you know of a type of store that usaually has this type of grill?

Thanks to both of you!

[LooseChange]

That grill is from Hammond. When you buy the chassis you will be able to buy a matching grill.

My trick for making the chassis perfect is to lay the entire thing out on a large piece of graphing paper. I then tape it to the chassis and mark each hole with a punch. I then drill a small pilot hole as exact as I can. After that it's all perfect.

[Tiago]

That grill is from Hammond. When you buy the chassis you will be able to buy a matching grill.

Thanks,
I know that Hammond sells that particular ventilated cover, but what I want is just the grill, like when you buy a sheet of metal per meter or per inch...do you know what type of store sells just that kind of grill?

My trick for making the chassis perfect is to lay the entire thing out on a large piece of graphing paper. I then tape it to the chassis and mark each hole with a punch. I then drill a small pilot hole as exact as I can. After that it's all perfect.

OK!
I think I will use a Pc based software and print on paper to do that... (I'm not very good marking things manually, even in graphic paper!!)
Thank you!

[LooseChange]

Check this link out for making your own graph paper.

http://www.incompetech.com/beta/plainGraphPaper/create.pl

[Tiago]

Nice link!
Thank you!

[Ptron]

Hello LooseChange,

I don't know if you're still checking this thread or not, but I'd be very interested in hearing about some of the mods you did and why you did them.

I'm currently working on a scaled down version of the Standard. It will only have a 2xEL34 output. I'm also ditching the FX loop, body & limit controls, triode/pentode switching, and line out.

[LooseChange]

Ptron,
Yes, I check in when I can.
I am working on a new build myself with many changes. See the Standard II on my website:
www.loosechange.freeservers.com

The types of mods are mainly value changes and switch options as related to your build.

[Ptron]

Nice job! I see you've opted to drop the "dual" output stage too. Tube rectifier too, eh. It looks like your keeping the "body" and "limit" controls. It also looks like you have the power scaling card in there but no controls, is this right? You said something to the effect of it not being that useful for you. I'm curious if that's because you don't like the way it sounds or if you just usually need all the power. The power scaling is the main thing that drew me to this amp. I bought TUT mostly to get the schem for the power scaler and add it to my own design. When I saw the standard I realized it was pretty close to what I wanted and probably much more likely to sound good than some crap I just made up;)

[LooseChange]

No body, no limit and no powerscaling in the Standard II. I added the tube rectifier because I like the sag best. I didn't really find much use for the powerscale.

I like the effects loop and reverb. On this amp, I concentrated more on the switching preamp.

[Ptron]

I almost left the reverb off, but I will probably occasionally use the amp with pedal steel, so I dicided to go with it just for that. I only use floor pedals so the effects loop is pretty useless to me.

What I'm curious about is why you don't find the power scaling useful. Do you think it sounds funny or do you just like the full headroom?

[LooseChange]

Exactly, I built the amp to play with my band. It's really no use.
I find the parallel effects loop great for time based effects like my Memory Man Delay. It puts the effect exactly where it belongs in the signal chain.

[Ptron]

looks like you've changed up the rest of the power supply as well(besides dropping the power scaling). Are you just getting the -bias and switching voltage off a leg of the HTsecondary? I've wonder why Kevin O'Conner chose the complex method he did to derive the -V supply. For those who haven't seen it, he uses The 5V secondary, normally used for tube rectifiers, and steps it up with second transformer. This seems unnecessary to me: extra transformer, extra winding on the PT. Doesn't seem like the switching circuit would draw enough current to worry about. Maybe the power scaling causes more current to be drawn from the bias supply than normally would be.

[LooseChange]

I went traditional on the power supply filtering because I used a Tube Rectifier. My B+ is at 460 with the 5AR4 so I had to beef it up.
I used a Weber transformer which is very well suited for this project. It has two sets of HT windings 720 and 660. I used the 720 for the B+ and I built my V- (bias) off of the lower winding (set at max of -75v). The transformer also has a Bias winding which I used for my switching card (derived -18v).

I guess I really can't call it a Standard anymore. I'm looking for another name.

[Ptron]

What did you use for the reverb transformer and pan? All I can see in TUT5 is that it says "316" for the transformer. This doesn't appear to be a Hammond #.

I just now noticed that this amp has no standby!?! What's up with that? There's no soft start circuit.

[LooseChange]

The 316 is a proprietary transformer that London Power has produced. You need to buy it from them. The only way around is to change that part of the circuit to a Fender type and use the everyday single ended transformer.

There is no standby on the "Standard". If you read TUT books they explain it's not needed on low power tube amps like this one.

My newest build is a Standard lookalike with the Fender style reverb circuit, a standby, no powerscale, a tube rectifier and only 2 power tubes. Take a look at that.

[LooseChange]

Update - long overdue!
I finally went back and changed around the powerscaling. I am now powerscaling only the power tubes. I like it. It seems to give me better tone when I scale back for more power tube distortion.

[teleamp]

Great thread Dan, I will be building a Standard in the near future.

Mike

[LooseChange]

Great thread Dan, I will be building a Standard in the near future.

Mike

Let me know how you progress. I can add some wisdom as you build.
Dan

[Ptron]

Haven't really worked on it since. My hobby time has been spent building a few pedals and playing in four bands, but I'm starting it up again. I was going to drop the reverb and the reverb mix/gain recovery stage (as well as the fx loop) http://music-electronics-forum.com/showthread.php?t=3132

One of my main goals is to simplify the amp and make it as light as possible. (see the line about playing in four bands and think about all that amp schlepping) This was supposed to allow me to use the Hammond 272FX instead of the original JX, saving 4 lbs. I thought the 150ma rating was enough but now I see this thread which blows that whole idea to hell
http://music-electronics-forum.com/showthread.php?t=3235

[LooseChange]

So all you really want id a two channel preamp attached to the 4 output tube power amp. Drop everything else?
If you want the JCM800 tone.. This is not quite that.

[Ptron]

Oh no. I'm not going for the JCM800 tone. I'm going for versitility and portability. I came across this amp because I was looking into power scaling. I like the idea of the fender-y clean channel...and KOC claims the dirty channel is first rate. I'll have to take his word for it for now.

By versitility I mean in a general sense; I mean that I want it to do both clean and dirty tones respectibly at range of volumes, not that I want a billion knobs and swtiches to tweak everything. I actualy plan to trash a lot of that stuff like the triode pentode switch, one of the master volumes, the fx loop, etc etc... most importantly, I'm going to ditch half the power amp and just go with pair of output tubes. I chose EL34s because...well...I guess just because I don't own an amp that has them yet.

And I'm pretty serious about this portability thing. I was even thinking of going with one of those Jensen Neodyne speakers to shave a few pounds. I have to drag my amps to 4 different practices in 4 different places every week. I'm so sick it and I will spare no expense and even sacrifice some tone (just a little:)) to make it just a wee bit smaller and lighter.

[LooseChange]

Has anyone started a Standard lately?

[Ptron]

I just went to the London Power site and I don't see the Standard anymore. I thought I read there a few weeks back that it was going to be updated, but for now it's not there. I wonder why?

[LooseChange]

It's still there... http://www.londonpower.com/kits/t5.htm

[LooseChange]

Is anyone still building the Standard?

[geoffrod]

I think i need to get me this tut5 book, i would like to build an amp to use in my band, primarily covers but some original stuff, i play rhythm mainly, we play blues, and rock and roll, i would be needing an amp that has a fender style clean, and can get a bit ballsie as well, i am tinkering with an amp at the moment that has way to much gain for me, so this may be the path i take.
does this tut5 book have all the info needed to build this standard amp???

cheers
geoff

[LooseChange]

Yes. TUT5 has detailed instructions on how to build the Standard. It's also a great book!

[gribnick]

I have been curious about this amp for a couple years now but have been unable to find any clips of it anywhere. You say it is "not JCM800ish", but what is it? My situation is that I am a detuned baritone and 7-string heavy-tone player and don't want to invest the amount of time and effort that this sort of amp would require that then won't do what I need and want it to do. I heard the 45 second clip on your page and it was a nice sound but I don't know what that represents. Is that the clean channel with bark or the gain channel hardly up or was it near maxing? I need something with several times that amount of gain. Can you characterize what this amp is capable of in definable terms? The problem I run into is people say "amp has metric buttloads of gain" but they normally play clean so a couple scratchy barks and the amp is over the top whereas that same statement to me is more like pantera or something. So are we talking gain of AC/DC (what decade?) or less british or .. ???

Sorry for the diatribe but getting a description of this amp has been like trying to catch an eel. Now finally I can talk to someone who has one ... :D