KOC Standard Amplifier - has anyone ever built or heard one?

[stephenl]

KOC Standard Amplifier - has anyone ever built or heard one?

Has anyone ever used his toroid power supply kit?

Has anyone ever used his PA kit with the toroid OT?

There seems to be little to no reference other than his website....no youtube videos, reviews, barely any comments on any of the forums.

[John_P_WI]

Ian, Gingertube, is the Standard man here. It is a very complex build and delivers.

Many of us here have used London Power products with much success. Kevin's kits are well thought out and use high quality components. Sorry I can not answer regarding the specific product that you asked about.

[NickC]

Here is a YouTube of a DIY London Power Standard:

http://www.youtube.com/watch?v=7psOWQXAyQQ

[John_P_WI]

Nick, I believe that video was from a poster named Dr Dog??? over at the now defunct powerscaling.com. Unfortunately IMHO it does not capture the flexibility of the Standard. Kevin has shown numerous variations of the standard preamp in his books which basically captures the essence of Fender and Marshall voicings. The later generally being shown as 3 gain stages with a plate loaded tone stack with a recovery gain stage before the PI. Kevin always suggests tweaking the circuit to your needs. I hope Ian will add his comments.

[gingertube]

Steven,
Yes I built one for friend Neale.
I did a eyelet board using the layout from TUT5 but purchased a power scaling kit from London Power and then modified it to add the SAG ("Compression') Control.

Used his schematic exactly for preamp, channel switching, reverb etc.
Used a spare JTM 45 Output Tranny I had and drove it with a quad of vintage 6V6G (the old ST "coke bottle" shape). I did not implement the "Body" control, just used a dual gang pot for the post PI "Limit" control.
I also did not have swicthing on every output tube but switched them in pairs. That is, each of the 2 output pairs could be switched between triode/pentode and fixed/cathode bias.

We tried 4 different reverb pans and settled on the Accutronics 6 spring long delay.

The guy I built it for loves it. For me it has just too damned many "bells and whistles".

The London Power Standard Preamp (LPSP) works very well and you can easily dial up most sounds you want.

I subsequently built a much cut down version for myself. Used the same preamp but with 6SL7 instead of 12AX7 and a single pair of 6V6 fixed biased pentode mode for the outputs, No powerscaling.

Cheers,
Ian

Pictures:
A final, the powerscaling baord and some during build shots, I have more shots if anyone is interested

[stephenl]

Nice work Ian!

I've used his PS kits in my own creations - nice stuff.

I was looking at his PS and PA kits with toroid PT and OT and noticed he offered the standard preamp as a kit as well. I'm considering trying them out but was looking for some references as to how they sound.

[gingertube]

Steven,
I'm more a seriously good tech but seriously average guitar player.
I find the LPSP (London Power Standard Preamp) really easy to use and sounds great.

The things I like:
Separate tone controls for the two channels - multichannel amps with one set of tone controls are so limiting.
Easy to implement electronic (footswitch) channel switching which is another convenience thing.
There is a overlap between the clean channel flat out and the lead channel at lower gain which gives you 2 options for those Blues and Trad. Rock sounds.
The clean channel takes pedals nicely (it really is just a standard Fender).

On the version I did using 6SL7 instead of 12AX7 I found the Clean Channel was a little marginal on gain but the Lead Channel was glorious and I was able to dial up the exact level of overdrive I wanted and having set that could then control it nicely off the guitar.

One of the guys I occasionally jam with of a Sunday afternoon used the 6SL7 version just once and immediately asked me to build one for him.

I know the LPSP does not necessarily follow many of the "popular wisdoms" in preamp design. Kevin has his own philosophies when it comes to amp design, for example
- no DC coupled cathode follower for the tone stacks, Kevin believes that tione stacks are more reactive when anode driven + saves a triode stage.
- gain stages are all centre biased rather than stagered (Hot - Cold etc), Kevin believes this gives better sustain.

I like it, as do all the guys who have used the original Standard I did for Neale or thE 6SL7 version I did for myself.

I haven't had them tried by a serious "shreader" however, not sure on the super high gain performance but would suggest that it was never really intended to go to that territory.

For inexperienced builders on a budget who want a reasonably well documented Fendery Clean Channel + Marshally Lead Channel from just 2 off 12AX7 then the LPSP is the go. Do it yourself or buy a kit from London Power. I think you'll be happy.

Cheers,
Ian

[stephenl]

Thanks Ian, that was very helpful.

[ampgeek]

Very cool build going on there!

I have built a handful of 5F6As with all 6SL7 (5691's actually) pre-tubes and simply love the tone/feel using those bottles.

At the risk of sounding like a complete Neanderthal....is there any way that the KOC Standard schematic can be shared "on the side"?

I have ZERO intentions of anything beyond one-off builds for myself and a small group of friends/children of friends as gifts/novelties.

Rock on,
Dave O.

[katopan]

These might help:
http://www.harmonicappliances.com/toner ... cript.html
http://www.ax84.com/bbs/dm.php?thread=64136

[gingertube]

the Toneraor "t1descript" schematics are "damn close" in the preamp section.
The LPSP of the Standard does not include D8 and D9 or the "Thick" Switch SW9 or the tone stack lift switches (otherwise identical right down to component values). The switch options are things Kevin discussed. I don't know where the D8/D9 came from and as far as I can see they are a waste of space and do nothing (They are permanently reverse biased). The standard channel switching is done using JFETs under electronic control with footswitch + panel switch control. The electronic control is pretty simple - it requires the front panel switch to be left in clean position for the footswitch to work.

The power amp in those schematics shows a Concertina Phase Splitter the Standard runs the "standard" stacked Schmitt Differential Splitter that you see in 90+% of all guitar amps.

Here is some scribbles from my work book for the 6SL7 version - design is entirely based upon Kevin O'Connor's LPSP.
http://www.londonpower.com/all-kits/2-c ... tar-preamp

Cheers,
Ian

Cheers,
Ian

[gingertube]

The higher voltage rating JFETs for auto channel switching are sometimes a bit hard to find or expensive.

Being a design eng in in the day job means that all the IC manufacturers send you their latest product release blurb.

This one from Analog Devices this week. Looks good for tube amp channel switching.
http://www.analog.com/en/switchesmultip ... oduct.html

Cheers,
Ian

[LeftyStrat]

It's a shame there is not much out there for showcasing Kevin's designs.

His sales might go through the roof if he could find one decent guitarist to record some stuff.

I'd love to build some of his designs and buy some of his kits. But without a definite example of the tones available, it's hard to invest the time, or money (his kits are a bit pricey) without any recordings.

The lack of recordings makes it seem like he is hiding something. Hell, if I had designed an amp that would knock you're socks off, I could go to a local studio and give them an indefinite loaner in return for some clips.

I wouldn't buy a painting without seeing it, a record without hearing it, a car without driving it. How hard it is to find someone to make clips, when you've been making amps and writing books for years.

I have far more respect for the amp builders here who post clips of their designs.

Show me the tone.

[stephenl]

Ian, any chance you could record some clips to share?

[ampgeek]

Thank you gentlemen!!
Dave O.