Started DClone

[Blues Hound]

Heisth,

I will do that until I complete the new board.

Voltages:

B+1 = 439 VDC
B+2 = 437VDC
B+3 = 421 VDC
B+4 = 304 VDC
B+5 = 297 VDC

V1: Pin 1 = 180.1 VDC, Pin 3 = 1.728 VDC, Pin 6 = 179.8 VDC, Pin 8 = 1.725 VDC

V2: Pin 1 = 195.4 VDC, Pin 3 = 1.596 VDC, Pin 6 = 198.2 VDC, Pin 8 = 1.554 VDC

V3: Pin 1 = 298 VDC, Pin 2 = 33.2 VDC, Pin 3 & 8 = 54.4 VDC, Pin 6 = 291 VDC, Pin 7 = 34.8 VDC

V4: Pin 1 = 430 VDC, Pin 3 = 3.13 VDC, Pin 6 = 166 VDC, Pin 8 = 1.923 VDC

Some Pictrues:

Preamp section

[img768]http://i394.photobucket.com/albums/pp25 ... -08001.jpg[/img]

Power Section

[img768]http://i394.photobucket.com/albums/pp25 ... -08002.jpg[/img]

Preamp Board

[img768]http://i394.photobucket.com/albums/pp25 ... -08005.jpg[/img]

Steve

[Blues Hound]

Rewired the 12v Relay board using the CT and one lead, 17.8 VDC to the 7812. Switching is transparent.

I currently have this in a 4x10 combo with 2 Scumback 75M's and 2 75H's, and sounds amazing.

The OD is smooth not edgy, very sweet. The clean channel with the PAB engaged is very complex and singing, just an amazing amp.

I decided to see how it would sound through a 12" speaker so I plugged in my 1x12-1x10 cab, again with Scumbacks...it sounds even better and I am now convinced that 12" speakers are the only way to go with these amps.

Power Tubes are RCA Blackplate 6L6GC's biased at 41.4 ma
Preamp tubes are V1: GE 5751, V2: GE 7025, V3: RCA 7025, V4: GE 5751

MM Bassman PT and OT

Norman - thanks for the inspiration and work you did on developing this configuration.

Dogears - thanks for the work you did with Norman.

What a great place to have as a resource for building a great guitar amp, this is the second amp from this site that I have built, the first one was TW Express that is absolutely amazing.

[Structo]

I've been following your build and you ended up with a great looking amp.

How many preamp boards did you make anyway?

I have a couple questions if you don't mind.

What did you end up for your dropping string, value wise?

And where did you buy the trimmer for the PI?

Thanks

[Blues Hound]

Structo,

Thanks for the Kind words...

I built two boards for this amp, the first was a more Fenderish type with turrets and was too long for me to have the filter caps inside the chassis.

The second was patterned more like #124 with reverb added, ended up at 8.5" x 2.625" - componets laid out at 3/8" centers.

There is something about having the filter caps inside the chassis as opposed to outside, I don't know what, but it makes a difference.

Dropping string is like #124, 100K's with a .047 mid cap, thanks Dogears, 1.5K with 10uf caps for CL1 and CL2, 1.5K with 4.7uf caps for OD1 and OD2, 100K Trimmer with 180K to OD output.

After reading Gil's posts about the 100K amp he built, I decided that was the route I wanted to go.

All parts were ordered through Mouser, I will post the part number tonight.

[Structo]

Thanks, what I meant was the resistors that control the B+ to your preamp tubes on the ends of the filter caps.
Did you follow 124 or did you adjust for the voltages you arrived at.

[Blues Hound]

2.2K - 22K - 2.2K all 2 watt

[Structo]

Hi Steve,
Did you happen to have the Mouser # for your PI trimmer?
Thanks

[Pete]

Hi Steve,
Did you happen to have the Mouser # for your PI trimmer?
Thanks

Hi, I'm not Steve but it looks to me to be a 531-PTC10H-(value) or 531-PT10H-(value) I've used these with good results, they are a stand up version of the other (black) one in the pic. I seem to recall seeing these in builds by others as well. [my $ .02], HTH

[Blues Hound]

Structo,

The Mouser part number is: 531-PT10H-25K

Steve

[JimiB]

what scares me about those is the .15w rating.
Steve - will you measure the voltage on all three pins of that trimmer and post them?

[Blues Hound]

B+3 is 421 VDC at center lug in front, I will have to measure the right and left lugs tonight.

So far, so Good, played the amp for two hours last night with no issues.

[Structo]

Yesterday I ordered a couple different trimmers from Mouser.

I didn't know which one Steve had used so I tried a couple different ones.
It seems about the biggest wattage ones are 1/2 watt.

I bought one BI Tech Mouser # 858-37WR10KLF

And a Bourns # 652-3352E-1-103LF

These are 10K trimmers.

I just hope they aren't the real tiny ones.

I find it hard to interpret the data sheets and measurements.
But hopefully these will be on the big side since they are 1/2 watt.

[Structo]

Seems as most of these trimmers have a voltage rating of 250v.
Is that going to be big enough?

[heisthl]

Seems as most of these trimmers have a voltage rating of 250v.
Is that going to be big enough?

There is only about 10 volts on that trimmer.

[Structo]

Really?

I suppose due to the voltage drop across the plate resistor there isn't much on the trimmer, I just assumed it would be more.