Portaphile V2 Owners Thread - Page 12

Hi Jester, do you have an update on the comparo?

Well, I lost the timing. But this morning I had a CD on: fine at the beginning, but characteristic noises of exhaustion at the end. I measured the battery voltage as 6.1v at that point. That battery's life was at least 17 hours, may be more. Battery life was not close to that when I first had the amp, so I'm not sure what's going on with this.


At 14 hours I measured the battery's voltage at 7.3v and compared its performance to a fresh one. Very small difference, if any.

I've been much too busy to log battery longevity with P-V2. Also, I'm only using recharcheable NiMH batteries: Plainviews and Ansmann 250mAH. With the early V1 I tried Ultralife Lithium 9Vs and got roughly 35 hours out of them. I haven't tried these with V2 since they're $10.95 near here (Radio Shack) and the RS deal of buy 2/get 2 ended long ago. It's possible that V2 uses more current than V1, but it's odd that you've gotten different results since your unit was new!

I measured my V2 current drain to be 28 mA, so an Ultralife lithium should last about 36 hours assuming a cutoff voltage of 7.0V -- that's where the voltage starts to fall off a cliff. You can buy them from Mouser for around $6 depending on quantity.

I have been using 250 mAh NiMH rechargeables and get around 9 hours before I start hearing the end-of-life "squeals". It's a pain having to use a snap connector at such frequent intervals, however, and I'm getting worried about the long-term reliability of steel thumbscrews mating with those very shallow threads in the aluminium housing. It's way too easy to cross-thread them. I would much prefer threaded steel studs permanently embedded in the case (with Loctite) and steel thumbnuts, as used by the Supermacro and SR-71.

$...!!!

THANKS! CHEAP! GOOD!

All this is very true, but it's worth noting that because Cesar chose to use the snap connector, the Portaphile isn't so dependent on its back attachment as the SR-71 is. The back isn't doing the job of holding the battery against the contacts.

The lack of tension is certainly a mitigating factor. In the cases of the SM and SR-71, the fixed studs are really a necessity for that reason alone. But remember that you don't have to remove the backs of these amps as often: it's the frequent threading and unthreading that could be the Portaphile's "undoing", particularly with the minimal thread depth in the aluminium part. Steel screws in tapped aluminium holes, even with full thread depth, is not recommended practice if the screws get a lot of use. Another option Cesar might consider is to put threaded steel inserts (Helicoils) in the case.

hardware details...

It would be desirable to have more durable options for battery contacts and back panel hardware. I'm familiar with the SR-71's steel posts and thumbnuts. They seem to be Ray's typical "mil spec" quality and they are very costly, judging by notes I've seen that the replacement price for lost thumbnuts is $15. Further, they are a bit small and seem to be much easier to lose ("oops - drop and roll - gone") than thumbscrews. I didn't know the SM uses similar hardware. The photos I've seen have shown large head thumbscrews, unless the newer SM cases are different.

I don't like the snap-on battery contact either, but I expect it's another space&cost issue.

It would be nice if Cesar could come up with more durable/convenient options that would not significantly increase the cost of the amp. I expect, though, that those would bump up the overall price.

If you can think of cost-effective solutions to these problems, bring-em on. Perhaps your suggestion of "...threaded steel inserts (Helicoils)" would help reduce cross-threading and stripping tendencies. I have no idea how that would impact the price.

A quick check around a couple of engineering suppliers suggests a non-recurring investment of around $75 for installation hardware (special tap, installation tool and tang break-off tool). The actual threaded inserts cost less than 25c each in quantity. It would add no more than 5 minutes to the assembly time for each new Portaphile and could be retrofitted to existing cases. Another possibility might be to offer inserts as an extra-cost option when ordering (i.e. take a leaf out of Xin's book ).

Burn in phases?

Has anyone experienced a distinct 2nd "jump" -- or even any smaller changes -- during the burn in process, after the 1st jump (around 120 hours for me) wherein the bottom end opened up, got deeper and the overall sound got warmer?

I'm closing in on 200 hours (not yet) and haven't heard another significant shift yet. Somehow, I'm expecting more adjustments to the overall sound -- but it might just stay where it is. I'd like to know what experiences and impressions other owners have had.

How would you describe the changes from new, and your impressions of the overall sound?

New sounds...

Too busy at work to say much, but a good friend lent me his DAC1 and Sony SA5000s. They've been making my endless workday very enjoyable (oh I am a sick puppy!). My work setup is generally Mac G5 tower > usb cable > Sonica USB Lan-BGMod > Zu Pivot .5m IC > Portaphile V2 > AKG K501.

Today: Mac G5 tower (iTunes w/mostly Lossless files & some 320AAC) > optical out > DAC1 > 501 and SA5k OR DAC1 RCAs out > Zu Pivot 1m RCA-to-mini > Portaphile V2 or SR-71 > K501 or SA5k via Zu Pivot 1/4-to-1/8 adapter (...adapter just died, so no more of that).

DAC1 is delicious on its own. Surprisingly, P-V2 has nice synergy with DAC1 and tho' it loses the inky black background, open air and super spatiality of DAC1, it adds a fun bit of oomph -- a bit more bass and impact -- as well as imparting rich, lush fullness to vocals and fuller sound overall, and still keeps a good sense of performance space and solid placement of instruments, voices and ambient sounds.

The SA5000s are great. They sound wonderful with DAC1, P-V2, and SR-71. When they hit the market full force and prices drop, they'll be on my list (unless I hit the lottery and buy Qualia and all the other toys in the store...). K501s hold their own, and mate very well with DAC1. Though volume has to be cranked 3 or 4 points higher than SA5000, DAC1 gives 501 rich bass and beautiful, warm and relaxed sound. P-V2 drives my 501s with no problem. DAC1, P-V2 and SR-71 hi-gain seem to have roughly the same output levels.

Since P-V2 drives my 501s so well, I can't imagine much short of K1000 that would have difficulty -- but I haven't studied the stats or auditioned a lot of phones with it, so I don't know for sure. I only know that 501s are notorious difficult to drive well and P-V2 does just fine.

Bye for now.