London Power Standard - finished pic and soundclip

[stephenl]

Faceplates from Front Panel Express-12g black anodized aluminum backfilled w/white paint.

Chassis from Seaside.

Boards and transformers from LP. I just finished stuffing the boards.

This is my first PCB build and my first multi-channel amp.

I apologize in advance for not posting schematics for those who are interested. Most of the design is available in TUT3 and TUT5. Pieces of it have been been posted elsewhere. It's his IP and I respect that.

The preamp is basically Fender Clean and Marshall OD.

The circuit boards and components are good quality.

[vibratoking]

The amp looks cool. I've wondered about Kevin's designs. I'd be interested in hearing some clips when you're done. Whos' feet? Those look bad...

[John_P_WI]

Rock on, looks great, it should be a great build. I've messed around with Kevin O'C's designs since the mid-90's, and it will deliver.

Bet Ian (gingertube) will chime in, he built one from scratch a few years ago...

Most definitely, post a few clips when done.

John

[M Fowler]

Looks great.

I've never mess with O'Connor's designs but have used frontpanelexpress and seaside chassis. Love the fan cutout on the back panel.

[gingertube]

Yes I built a "Standard" from scratch (used a Hammond Chassis).
I used a quad of 6V6 for the outputs and a JTM45 Output Tranny.
I also used just 2 Triode/Pentode Switches (one for each output tube pair) and similarly just 2 cathode./fixed bias switches, (again 1 for each output tube pair). Tried 6 different Reverb Pans and settled for the full length, 6 spring (Accutronics type 9), long decay as best although if you are a "shreader" player then a medium decay might suit you better. The Reverb Pan was painted black and mounted vertically across teh back of the amp.

The amp looks better than the attached pic. Labelling was done using a white on clear tape in a Brother "P-Touch" label maker. The labels flared a bit with the camera flash.

Other threads:
https://tubeamparchive.com/viewtopic.ph ... 12506eeb3e
also my poweramp/powerscaling set to work notes are at about post#10 here:
https://tubeamparchive.com/viewtopic.ph ... 358dfbe184

Cheers,
Ian

[stephenl]

Nice looking build Ian!

I'm going with a 2x KT66 25 watt output, no feedback, switchable cathode/fixed, switchable UL/Pentode, no triode mode, powerscaling.

I decided to not put in the effects loop or reverb. I love good reverb but tend to like time based effects after the amp.

I was kind of on the fence on the sag control and decided not to implement it. Did you end up liking that function?

Did you try the "Body" control?

[gingertube]

Steven,
I ran out of panel space so I ditched the "Body" Control, that allowed me to use a dual gang pot as a Post PI Master for the "Limit" or "Drive Compensation" (or whatever you want to call it) Control.

I found the SAG Control ("Compression" if you prefer a pretty name) did not seem to have much sonic effect until right down one end of its adjustment range (I talked about this in one of the linked threads). I felt that for the sake of a few extra cents worth of components that it could be left in BUT if short of panel space for the extra pot then it could be dropped with very little compromise .

The 4 big knobs on the RHS are (L to R)
MASTER VOL (pre PI), DRIVE COMPENSATION, COMPRESSION (SAG), POWERSCALE

Cheers,
Ian

[matt h]

(deleted)

[gingertube]

matt h makes an excellent point.
Ultralinear makes extra demands on the power supply - it needs to be cleaner, that is more filtering and hence a "stiffer" supply.
On my build of the "STANDARD" I did'nt have UL taps so TRIODE/PENTODE switching was what I implemented. This amp was built for my friend Neale. I had a bag of Panasonic ED 22uF/450V caps and just added extra on the mian B+ filter till it sounded "right". Ended up with 3 in parallel (66uF) for the main B+ and an extra on the screen supply. That was for an amp which delivered 32W max at the onset of clipping. That should to suit your pair of KT66 too but I would just use whatever the kit from Kevin specifies, at least for a start. Picture of my home brew power amp board attached.

I also built a "cut down" version for myself. It used the same LPSP preamp but with 6SL7s subbed for the 12AX7s and a 5E3'ish power amp with a 6SL7 and a pir of 6V6G. On that I used this Output Tranny:
http://www.mableaudio.com/en/productvie ... ormer.html

I did implement Ultralinear/Pentode Switching on that and I like the tightness of Ultralinear Mode even when using the LEAD Channel. Most guys who have tried the amp prefer it in UL mode (Exception is one "shreader" Lead Guitarist who prefered the loosness of Pentode Mode).
I used a JJ 50UF + 50uF 500V main cap for a total of 100uF B+ filtering on what is effectively a 15 Watt Amp (more like 10W in UL mode).

Out of touch for the next 6 days, will check back in next week to see what others had to say.

Cheers,
Ian

[matt h]

(deleted)

[stephenl]

The LP power supply has a sufficient amount of capacitance. It also has an active filter to reduce ripple without making it too stiff.

[stephenl]

I finally had a chance to finish wiring and power it up.

My initial impression is ... It delivers! Very good Fender cleans and Marshall growl and lead overdrive.

The noise floor is lower than anything I've ever heard.

UL mode is actually quite nice and useable. It's set up to hot switch between UL/Pentode mode with relays. If you're not playing, it makes a slight pop. If you are playing, the tranistion is barely detectable.

It also has PowerScaling and selectable fixed/cathode bias.

So far, I would highly recommend this build.

I'll post pics soon.

I need to set up my recording gear so I can post some clips.

[John_P_WI]

stephenl,

That is great that you are happy with the Standard, job well done and Congrats!

Looking forward to the clips and pics

John

[V2]

looks great, and I'm eager to see more gut shots and hear some clips. I am currently using KOC's 10-watt transformer set, and although I created my own eyelet boards, I do have the LP power supply board for a future build. KOC sent it to me with the parts preloaded onto the board - his soldering is a work of art. And talk about a clean power supply. Nothing I have seen comes close.

And I plan on ordering his 25-watt transformer set for a future build.

[V2]

Any updates (photos or clips)?

My current amp project also uses a LP toroidal transformer set, and I am having problems with 120Hz buzzy hum. I think my PT and OT are too close together. I'd like to see how you mounted the transformers...