Don Imlay's Phase Linear 400 Series II Quasi -Comp.

[Gepetto]

Could be Mark, Fluke does not really specify the meter performance at those frequencies. Which meter was reading strangely? The 70 or the 112?

 

[Skratch]

Joe, The 70II meter, was fine until about 10k Hz and then started to drop while the other 112 meter rose. The interesting part was that on the scope both channels were identical and clipped at the same time at 42 volts at 20k Hz

 

[Gepetto]

Thanks for confirming, suspected that. While the Flukes are very good, I only trust the scope or the 8903 for measuring audio signals.

 

[laatsch55]

Are those model Flukes RMS? If not that could be your problem. My 179 has tracked with my scope and now with the AP analyzer, VERY good DMM. Wasn't that expensive either, 229.00 for the meter, case, 4 different leads, and spare fuses.

 

[laatsch55]

Having some issues with the cap kit. I know Don does not like extranneous hole drilled in the chassis, but we may have to this time if no one else has a better idea. As of right now the only thing holdin the assembly in place is friction against the tranny input grommet.

I'm proposing a bottom hold down clamp anchored to the side of the chassis, like some are. The tranny casting strap will keep them moving from vertically and the hold down clamps from moving laterally.

 

[Skratch]

Men The Fluke 70II meter I don't think is RMS while the Fluke 112 is RMS. Never too old to learn something new. Finished my second total upgrade with the White Oak board. My friend came over and we hooked it up to my Altec Santiago's and let it rip. Sounded great and he said it was the best the amplifier ever sounded.

 

[Skratch]

Did one of you guys purchase the 700 Series 1 that was relisted on E-bay?

 

[laatsch55]

The buy it now for 375??

 

[wattsabundant]

Sorry I've been out of touch lately. The fluke 70's are not true RMS. Average responsing, calibratedd to RMS value.

The cap board is a prototype that will get a new layout. The intent is to make some kind of a clamp similar to the original that was on this amp.

Lee drill away if need be as this is my amp. I oppose the drill to maked it easier for the average guy to do mods. Also this allows the amp to be returned to stock if someone does like the results.

 

[laatsch55]

OK will do Don. Just need 2 small #6 holes in the side there to facilitate some bottom clamps.

 

[wattsabundant]

The relay board in this amp was a prototype. The current version is slightly smaller.

I violated my own policy of changing out all the outputs. I reused the originals and replaced the bad one with similar date codes. The amp was put in sevice and left on 7-24. One day for no reason it just let go. Fortunately the relay did it's job. No damage to the speakers (ESS AMT 1A).

 

[laatsch55]

I think the RCA-410's in this one are rather noisy. I've run about 10 hours of THD & N testing on this amp and I may change the 410's to 15024's to verify this.

 

[laatsch55]

Also Don, on the cap board, if you could make the isolation band around the non-conductive pin pads much larger it would help. After bending the tabs over and soldering the tabs were rubbing on the live portion of that conductive field. I desoldered and brought the pins upright and checked continuity, there was none, I will cut the pins off flush so there is no chance of shorting.

 

[mlucitt]

Lee, it could be good to have a comparison between several 410's and the MJ15024's. I think the 410's sound "warmer" that is probably the noise I hear coming through, but I think it sounds OK, not tinny and edgy like some other audio output transistors, probably because they are not near saturation. I would not be surprised to see up to 5% distortion on the 410's, but if it is "good" distortion and not the bad stuff - then not so bad and easier on the ears.

 

[laatsch55]

I will rotate some 21194's as drivers too just for shits and giggles.

 

[mlucitt]

U da man...

 

[laatsch55]

Got the cap brackets today in my Mouser order along with 500 2N 5088's and 500 MPSA 18's. We may be testing late tonight.

 

[mlucitt]

It looks like those clamps and those caps were made for each other, a nice fit.

 

[laatsch55]

Yes, 1-3/8 fit nicely on those what 40MM??


Progress.

 

[laatsch55]

Halfway there. Looks like I'll be checkin out those 2N5088's.