Finally

v846 · Post by **v846** » Sat Jan 14, 2012 6:52 pm

Hi All,

Finished my first Express on Tuesday ,well actually I built a spare parts Wreck years ago to try out the design and sample different iron, caps etc. I liked what the amp could do but it took me till now to build a proper version. Amp does sound and respond very nice, think I got lucky with my selection of tubes as there is no squealing even with all controls dimed.

Many thanks to all that provided parts and excellent posts that helped guide this build, fun winter project.
Built on Allyn’s chassis, UR12 boards, RJ Heybour PT & various bits from Ron Worley and of course used his excellent build guide. Despite the urge to deviate I tried to follow things to the letter from the guide & BOM.

http://s270.photobucket.com/albums/jj105/v846/Express/

David

Bob S · Post by **Bob S** » Sat Jan 14, 2012 7:08 pm

Beautiful - extremely well done.

M Fowler · Post by **M Fowler** » Sat Jan 14, 2012 8:23 pm

Nice clean built with PEC pots and grounding lugs very good.

I really like those boards.

ampmike · Post by **ampmike** » Sun Jan 15, 2012 12:01 am

That express build is perfect.One of the cleanest builds I have ever seen.
Wow!!!!!!Great work,Thanx for sharing,Mikey

v846 · Post by **v846** » Sun Jan 15, 2012 12:54 am

Thanks for the complements, really pays to go slow closely following the original layout and Ron's guide IMO.

David

Lublin · Post by **Lublin** » Mon Jan 16, 2012 2:39 pm

What a gorgeous build. Well done, OP.

Structo · Post by **Structo** » Mon Jan 16, 2012 4:28 pm

[IMG

768]http://i270.photobucket.com/albums/jj10 ... s/amp2.jpg[/img]

[IMG:953:538]http://i270.photobucket.com/albums/jj10 ... C05980.jpg[/img]

[IMG

590]http://i270.photobucket.com/albums/jj10 ... /board.jpg[/img]

Reeltarded · Post by **Reeltarded** » Mon Jan 16, 2012 5:15 pm

That is one that makes them look too easy. You must have done everything right.

It is beautiful!

rooster · Post by **rooster** » Tue Jan 17, 2012 11:41 pm

Wait. Tom, is this your build or did you post the pics for the first poster? I will assume the later, but either way, the build looks very good. Nice work.

v846 · Post by **v846** » Tue Jan 17, 2012 11:53 pm

Rooster that be mine & Tom thanks for posting them for me.

Build went OK with no major flubs and does sound nice but now that I’ve had some quality time with it uh her I notice there’s some hum in the speakers with standby on or off. Also notice a buzz or mechanical hum from the power transformer. I have various other Heybour pt’s that don’t buzz as much this one.Could be an inductive issue with the proximity of the iron or an issue with the PT itself?

Also with the amp in play mode there is some hum but considerably less than the hiss, V1 swaps help some. Hum increases with volume & tone controls turned up particularly bass. Dimed there’s more hum than I would like but I haven’t heard a real Express to compare what normal is. Maybe more tubes are in order.

So far
1. Verified my wiring & grounds then pulled V1 on back to the inverter tube and the problem persists.
2. Removed the OT bolts and moved it around but no difference.
3. Center tapping the heaters with 100r no difference.

In a band setting this wouldn’t be noticeable but the OC part of me doesn’t like it, maybe I’m being too fussy. I haven’t had the chance to play it wide open yet so maybe my perception will change once my ears are humming

Thanks,
David

v846 · Post by **v846** » Sat Jan 21, 2012 5:33 pm

Also noticed the buzzing power tranny vibrates enough it can be felt in the chassis. Wondering if it’s possible that the buzz/vibration is getting picked up and heard through the amp?

What would be the next step to determine the problem? I was thinking of removing the PT to see it still has the buzz out of the chassis.

Thanks,
David

MCK · Post by **MCK** » Sat Jan 21, 2012 7:31 pm

David, what a meticulous build. I recently completed my build as well following Ron's excellent guide and I must say your buyild sets the bar all the way up there!!! Well done.

I also have a Heyboer PT and noticed some hum from it. I am wondering if there is a rubber mount product to mechanically isolate the PT mounting legs from the chassis so that the hum does nto get transferred and amplified in microphonic sections of the amp. Something that might help. Please let us know how you go with this.

v846 · Post by **v846** » Sat Jan 21, 2012 9:24 pm

MCK,

Ah yes IIRC there was some mention here about a type of rubber washer or something under one of the PT flanges topside on Francesca perhaps for the same reason. I really don't mind some buzz & hums under the hood but not when it gets to the speakers too much..

Definitely worth a try, thanks for the tip and complement. I'll keep ya posted...

David

MCK · Post by **MCK** » Sat Jan 21, 2012 11:37 pm

Same here. Just to share what I have in mind, take a look at the following site

http://www.avproductsinc.com/

I'm thinking along the lines of an engine mount. Only much smaller. I'm sure something like this can be found.

Perhaps something like this :

http://www.vibrationmounts.com/RFQ/VM110104.htm

All the best

John_P_WI · Post by **John_P_WI** » Sun Jan 22, 2012 2:17 am

I have used small o-rings from the hardware store before for vibration damping. The silicon viton material ones do not dry out or crack as easily.

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