TLP & AKSA55

SamL · « **on:** 13 Dec 2004, 11:43 pm »

I can remember someone here did tried to build an integrated using AKSA55 and TLP but bail out due to humming. Will appriciate if you can share your experience.

TIA,
Sam

PSP · « **Reply #1 on:** 14 Dec 2004, 12:31 am »

Hi Sam,
That would be me. I'm working late tonight (just checking AC to take a 5 minute break let my brain cool down a little!), and when I get home I'm going to put some parts in my 55N --> N+ upgrade.

I will be happy to tell you the story, and what I ended up doing, in great length and detail. But... I have a very ugly day tomorrow, so can you wait a few days? If you don't hear in 4-5 days, send me a PM and I'll get on the stick.

Bottom line, my assessment is that if you put the TLP in the same reasonably-sized enclosure as the 55, you will get unacceptable levels of hum unless you shield the hell out of it, something I failed to accomplish, notwithstanding months of determined work on the problem. I am a hobbiest, not a professional when it comes to chassis layout, so I might have missed something. But when I pulled the TLP out of the 55 chassis and put it in it's own box, suddenly the hum was gone and the music beautiful.

I just built a TLP for my brother-in-law. I put it in it's own box, and it was lovely (and quiet) the first time I turned it on.

Talk to you soon,
Peter

DrDave · « **Reply #2 on:** 14 Dec 2004, 01:15 pm »

I put my TLP in the same box as my AKSA55 and had no hum problems. The box is not small (17"(w)x5"(h)x12"(d)). The TLP , Amp and power supply are well separated but there is no additional shielding.

PSP · « **Reply #3 on:** 14 Dec 2004, 06:23 pm »

Hi DrDave,
I tried to do it in a 17x14 2U Par-Metal steel and aluminum enclosure. I also had 6 source inputs, a Grayhill selector switch and a DACT attenuator. Although the signal path was as short as I could make it with my fat little fingers, I had way too much hum even with extensive shielding. By the way, before I built the TLP, I had run exactly the same layout using the Grayhill selector switch and DACT attenuator as a passive preamp. This was dead quiet, very detailed and extremely polite but not very involving. So, I put in the TLP, got hum, and shielded the hell out of things. I used two magnetic steel plates separated by about 3mm, with TI shield attached to both sides of the steel plates. The plates extended side to side almost entirely across the chassis. The torroids (Plitron), TLP transformer and rectifier, and AKSA power supply board were all placed behind the shield, power supply wires were twisted very tightly, and I did a great deal of playing with wire dress. The AKSA amp boards were mounted on the enclosure sides, toward the rear (much like a 100w AKSA is layed out) with the TLP in the rear center, so signal paths could be very, very short. All this to very minimal effect... still had lots of hum.

All my signal wire was either cat5 or 26ga Vampire cast magnet wire, both very tightly twisted. Maybe I should have used coax, but the coax I had on hand (Belden 89259) is very stiff and hard on the small connectors used on the Grayhill and DACT. I also have a strong bias against stranded wire in the signal path.

As I said above, when I put the TLP in its own enclosure, all was immediately right with the sonic world. I'd love to see pictures of your layout. Building a TLP/AKSA 55 based integrated amp would be a very nice option.

Thanks,
Peter

SamL · « **Reply #4 on:** 14 Dec 2004, 10:23 pm »

Hi DrDave,

Did you use power-on relay on your AKSA55/TLP intergrated? I wonder if there will be a loud pop when they both power up togather.
Do you leave your intergrated on all the time? I am a bit concern about leaving TLP on all the time.
Will be good if you can show us the internal photo of your intergrated.

Cheers,
Sam

DrDave · « **Reply #5 on:** 15 Dec 2004, 08:17 pm »

No, I did not use a power on realy. No big thump, just a bit of hum that fades away when the tube warms up.

I don't leave it on all the time but its attached to my computer so its on a lot. No failures yet.

I have one of the original TLP's. I've never even installed the update Keith sent out. Been that long since I had it open even. Someday soon I'll do the upgrade and take pictures.

I have 6 in's on the back and used a shaft extension to put the selector switch back there as well. The switch is mounted on a small box which would act as shielding so I guess I did do a bit.