Kev's "Gonna Sing Good" WOPL 400

[jbeckva]

83.5 on the rails.

-15 mV offset.

Bias dialed to 380.

Time to slap this guy together and give a listen...

 

[jbeckva]

DONE DEAL!!

Fwuuuuck!! Hell yeah Kev, this one blows doors off without breaking a sweat! Punchy as hell..

(had it up too loud... it was crystal clear man... )

<iframe width="640" height="360" src="//www.youtube.com/embed/EHDBW_2iMv8?feature=player_detailpage" frameborder="0" allowfullscreen></iframe>

 

[premiumplus]

EEETTSSS ALIVE!!!!
Great looking wiring job, Jer. Good job!

 

[derek92994]

Fwuuuuck!! Hell yeah Kev, this one blows doors off without breaking a sweat! Punchy as hell..

(had it up too loud... it was crystal clear man... )

Nice! Blew the crap out of that camera microphone

 

[jbeckva]

Nice! Blew the crap out of that camera microphone

Hehe.. this is a lil lower in volume. Had me foot a tappin a lil..

<iframe width="640" height="360" src="//www.youtube.com/embed/_5sRMVMWoM4?feature=player_detailpage" frameborder="0" allowfullscreen></iframe>

 

[derek92994]

Hehe.. this is a lil lower in volume. Had me foot a tappin a lil..

Cool, will check it out when I finish this side of my Stylus drop.

 

[derek92994]

Must take some serious loudness to get those meters moving then

 

[jbeckva]

Must take some serious loudness to get those meters moving then

That's the D9's... I could NEVER go to the limit on a wopl'd 700 or my ears would bleed. 400's are pretty close to pushing it too.

 

[laatsch55]

Sweet! Are they flanged on one side? I'd hate to put my finger on one side of the board to hold them in place while soldering them in place.

That is a great idea Joe.

Now waiting breathlesly for a FaboNav Deluxe Model Two Cup Holder....

 

[Elite-ist]

Wow, Jerry, you did a tidy job of routing wires and the audio demo is the crème del crème when putting your hard work to the test.

Nando.

 

[Gepetto]

Now waiting breathlesly for a FaboNav Deluxe Model Two Cup Holder....

They will have to be D's

 

[laatsch55]

Amen...

 

[kevin]

Better go smoke first...

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Going to be real honest here Jer !!!!! I wouldn't know if it looked bad !!! LOL... But It looks great to me man !!!! Thank you a million for all your hard work !!!!

 

[Northwinds]

They will have to be D's

Double D's

Amp sounds killer! Man, I need to find some D9's soon

 

[Bill Stevenson]

Question concerning low imedence loads

Has anyone used a WOPL 400 to drive a low impedance speaker like an electrostatic? Impedance can drop below 1 ohm at certain frequencies.

 

[jbeckva]

Has anyone used a WOPL 400 to drive a low impedance speaker like an electrostatic? Impedance can drop below 1 ohm at certain frequencies.

I'm going to defer to Joe or Lee for the final answer, but I would say AT MINIMUM not without active cooling - especially with the 4 fin model.

 

[laatsch55]

Steve in Phoenix h as driven some 2 ohm infinity's with The Pig, a quasi WOPL'D 400 with no problems. The amp design itself will support it but you better have a healthy fan. If the internal protection circuit trips it and you are not blowing rail fuses the protect circuit can be disabled by lifting a leg of D9 or D10. FredR has done that to a couple he's built.

 

[Bill Stevenson]

Thanks Jerry. I am just trying to figure out the best use for my 400 after you work your magic. I will probably use it to drive a pair of KLH Ones that it worked quite well with for years. But electrostatics have appeal too, and if I go that way it would save a ton of money if my 400 would drive them.

 

[Northwinds]

LOL, I used to put a huge box fan on top of Blackie when she was screaming. Fins would be so hot you could not touch them for long. Fan made it run wicked cool at any volume level

 

[FredR]

Steve in Phoenix h as driven some 2 ohm infinity's with The Pig, a quasi WOPL'D 400 with no problems. The amp design itself will support it but you better have a healthy fan. If the internal protection circuit trips it and you are not blowing rail fuses the protect circuit can be disabled by lifting a leg of D9 or D10. FredR has done that to a couple he's built.

When driving Infinity 9Kappas with a WOPL 400 I would get a strange distortion in the mid-bass frequencies at about half volume and up. Turned out it was the waveform protection circuit kicking in when the current hit the limits due to the two 1 ohm dips in the speakers impedance curve. Lifted D9 and D10 as Lee indicated and all was well up to "way too loud". That disables waveform protection but average current protection is still in place with the fuses.

I was comfortable removing waveform protection based on Joe's comment that it was designed to protect the 909s, and with the MJ TO-3s in it is "overprotective". 9Kappas have a reputation as an amp killer but I don't expect any problems with the modern output transistors. A fan is a requirement for higher volume levels.

Fred