RainDog's Modified WOPL 1K - Second Phase

[RainDog911]

About a year ago, I built a Rev D driver board and put new transistors into a quasi-comp 700B. Joe, Lee and the community were really great helping out an enthusiastic noob. I enjoyed running the amp for a year but had been planning on going the next step. Finally, audio building season arrived (after Christmas but before spring) and I was able to get a years worth of scheming and dreaming out of my system.

Phase 2 includes:

• Cosmetic cleaning and update
• Improved RCAs and binding posts
• Rev E driver board, full comp.
• Full comp back planes boards
• Complete rewire with really nice wire (Thanks Nav!)
• BABB
• Direct signal path (bypass volume pots)
• New power caps
• LED board

The build went without issue. But there was a lesson learned - DON'T FORGET TO REMOVE THE UPPER SCREWS HOLDING THE HEAT SINKS IN WHEN POWERING UP THE FIRST ROW OF TRANSISTORS! Putting the screws in wasn't in the instructions, I put it in to hold everything in alignment as I learned the 'feel' for inserting the output transistors. The only casualty was a popped pico fuse on the backplane board. Better lucky than good, eh?

A few pics:

 

[RainDog911]

So I clearly brain-farted and ran the thermal cut out switch wires across the backplanes. That has been corrected (more on that later).

 

[RainDog911]

I upgraded the interconnect hardware with some nice but not crazy hardware. I wanted to use copper in the signal path. I used DH Labs RCAs which worked well with an insulating, reducing shoulder washer from a well stocked hardware store. The Cardas binding posts are Rhodium plated copper and make a much more positive connection with the locking banana plugs I have in my speaker cables. The Cardas posts required drilling but there was plenty of room for the larger bores. I only had red shoulder bushings available but even I can figure left from right on this amp. I added a 3 position switch where the aux power outlet was. It allowed me to run the amp for testing without the faceplate. And I did away with the filter switch in back. I made new common copper plates from OFC stock from McMaster. I'm sure the OFC is mostly academic but I indulged anyhow...

(Sorry for the crappy pics and my inability to rotate them.)

 

[RainDog911]

So after it was built, tested and sounding good, I dismantled and cleaned up the faceplate. I was the guy running his mouth about chrome plating the faceplate and having the original artwork re-silkscreened. However, after seeing some Burmester equipment at a Chicago audio show that was chromed, I didn't like the look. And the faceplate cleaned up really nicely. I installed Joe's blue LED board and did some further custom touches.



My knobs were pretty beat up. I also shortened the signal path by not wiring in the volume pots. To compliment Joe's blue LED boards, I chose some Bulgin ring illuminated momentary push buttons. The blue matches perfectly (not well represented in the pictures). I had to drill the switch bores out using a 3/4" drill bit. It wasn't "machined" per se but the inelegance of the hole was easily covered by the switch body and retaining nut. I found a switch driver board on line and used a 30A automotive style relay to do the actual switching duties. The second button is for VU meter sensitivity (I have a little troubleshooting on that yet...). I found some nice chrome hole plugs that fit the bores of the volume pots perfectly. In the end, I like the way it looks. Updated a little but still a classic beauty.

And this can not be repeated enough: Joe's boards and all the updates and support of this community in the end creates a very, very good sounding instrument with truly obscene power. Thanks to all!

Thoughts...?

 

[audiobob]

So after it was built, tested and sounding good, I dismantled and cleaned up the faceplate. I was the guy running his mouth about chrome plating the faceplate and having the original artwork re-silkscreened. However, after seeing some Burmester equipment at a Chicago audio show that was chromed, I didn't like the look. And the faceplate cleaned up really nicely. I installed Joe's blue LED board and did some further custom touches.

View attachment 20719 View attachment 20720

My knobs were pretty beat up. I also shortened the signal path by not wiring in the volume pots. To compliment Joe's blue LED boards, I chose some Bulgin ring illuminated momentary push buttons. The blue matches perfectly (not well represented in the pictures). I had to drill the switch bores out using a 3/4" drill bit. It wasn't "machined" per se but the coarseness of the hole was easily covered by the switch body and retaining nut. I found a driver board on line and used a 30A automotive style relay to do the actual switching duties. The second button is for VU meter sensitivity (I have a little troubleshooting on that yet...). I found some nice chrome hole plugs that fit the bores of the volume pots perfectly. In the end, I like the way it looks. Updated a little but still a classic beauty.

And this can not be repeated enough: Joe's boards and all the updates and support of this community in the end creates a very, very good sounding instrument with truly obscene power. Thanks to all!

Thoughts...?

Looks good RainDog.

 

[Gibsonian]

Nice work there. Thanks for sharing. How do you like the sound compared to your prior build with rev D board?

 

[Northwinds]

Very nice looking work!

 

[RainDog911]

Thanks for the feedback guys.

I'm not a good authority for feedback regarding Rev D and Rev E. I changed too many other bits for a true A/B comparison (not to mention 6 weeks of listening to a different amp). Furthermore, I can't claim to have golden ears. To me, the amp sounds noticeably better than before. I'd say smoother, greater detail and very dynamic. It is quieter but I think I had issues in my original back plane that I wasn't capable of diagnosing. It still isn't "in space no one can hear you scream" quiet but I think i'm getting noise in through my AC. I'm working on a power filter to see if that quiets it down to how others have described theirs.

The reason I built a new Rev E board is so I didn't have to convert my quasi-comp D to full comp. I realize it is possible but I thought I'd be less prone to error (and more fun) to build a new Rev E. I'm keeping the Rev D because I'm looking for another fixer-upper so I can do this all over again.

 

[RainDog911]

One of the cool features of the switch driver board is that it has a built in shut off circuit for thermal protect switches using DC. This means I don't have to run one leg of AC across the driver board and down to the switch locations. My wires now run directly from the switch over to the power transformer while retaining thermal protection. Also, the front panel switch color will change from blue to green during a thermal "incident" (blue/red switches are available and would be a better choice).

 

[NavLinear]

Very nice work on the amp RD - this is not beginner stuff. The wire looks sweet and the build reflects that.

 

[laatsch55]

I see you and I have an altogether different idea about what a BABB is.....Seriously RD, nice job. Love the resourcefulness on the faceplate and associated goodies!! Well Done!!

 

[grapplesaw]

One of the cool features of the switch driver board is that it has a built in shut off circuit for thermal protect switches using DC. This means I don't have to run one leg of AC across the driver board and down to the switch locations. My wires now run directly from the switch over to the power transformer while retaining thermal protection. Also, the front panel switch color will change from blue to green during a thermal "incident" (blue/red switches are available and would be a better choice).

Hi
i missed the information on the switch driver board
can you post photo and part number
nice work on the build