Portaphile V2 Owners Thread - Page 8

Thanks for the reply, Bobeau. Actually I did see it and replied earlier that it's probably a combination of both (burn-in + brain adjustment), etc. (as you know I get wordy so I'll skip details here).

I'd like to hear from the silent majority out there. But as I keep repeating, a lot of hours of burn are needed for it to really mature. Even I get impatient, but I'll wait. I've already noted that the unit I have has only 60+ -- well, now maybe 70+ hours and the bass really hasn't open up yet, though it's warmer and well-defined. The burn in cycle hasn't been as wild as other amps I've had, but its character has shifted around somewhat, so patience is required.

What about the batteries?

The current crop of buffered portable amplifiers puts a strain on the power source far greater than that of the op-amp-output designs of the past. Since the op-amps (in most cases, see later comments) are already operating close to their minimum supply voltage requirements, it doesn't take much of an instantaneous increase in current to potentially drag the supply voltage down to the point where the manufacturers' power supply rejection ratio (PSRR) specifications are no longer valid and intermodulation distortion becomes noticeable. The ability of a single BUF634 to source up to 250 mA, or multiples of this if stacked, only makes matters worse. Certainly, the addition of large power supply capacitors, of varying quality, will help to hold the voltage up but the internal impedance of the battery/power supply is also a significant factor.

I recently returned to my faithful Porta Corda (Mk I) after a brief affair with a Total Bithead. At first, I was disappointed with the sound but I soon grew accustomed to it. I then swapped the (reasonably fresh) alkaline 9V battery for a NiMH rechargeable and was quite surprised at the improvement. The bass tightened considerably and the soundstage broadened appreciably. Both of these effects are consistent with a "stiffer" supply (i.e. less modulation of the supply voltage by the music waveform). This is an amplifier that includes 2820 uF power supply capacitance and has no buffers after the LM6171 op-amps.

It makes me wonder how long the SM can run with OPA627 op-amps: according to Xin, this op-amp likes a supply voltage of at least 9V, so even with a fully-charged battery (9.6V) there is very little margin. No wonder he strongly recommends NiMH rechargeables. Cesar's decision to go with the AD8610, which is OK down to about 5V, seems a sensible one. It also suggests that Ray Samuels was very smart to allow space for two 9V batteries in the SR-71 so the supply voltage stays well above the good PSRR threshold even with depleted batteries. And what are those oft-remarked special qualities of the SR-71? Did I hear "bass" and "soundstage"?

I would be interested to hear if anyone else has noticed significant differences in portable amplifer performance with different battery types. Perhaps reviewers should make a point of mentioning what battery they were using when they formed their impressions.

Actually a fully charged SM is closer to 10.4 to 10.6 (8 AAA batteries which routinely charge to 1.4 volts each and at 1.2 that still equates to 9.6 volts). Also in my experience until the unit finally fades out the is no real degradation of sound, which is often a run time of 50 plus hours.

John

I'm using Powerex 9.6V rechargeables for burn-in. At a high volume level, the amp runs out of juice in about 6-7 hours non-stop. Unlike the SR71 which goes dead silent (click!) when the battery goes too low, I do hear some periods of distortion with the Portaphile when the battery is about to die.


When I had my SM V1, it was loaded with 637s and the battery life was a dog. The amp runs really warm after 10 minutes, and the batteries were completely drained within 4 hours. Before it dies, you'd hear a screeching distortion. No matter what Xin says, I don't think the supermacro works well with 637s (either that or I got a defective amp).

He did some changes so it would work correctly with the 637. With the 627, which has a pretty good current draw, I get excellent battery life. It appears yours was defective or needed to be updated. That is unfortunate as I find it to be the equal of the SR71 except possibly the very black background of the 71.

John

It could've been defective, but I must say I can't relate with your statement at all since I found the difference between the two amps to be night and day. Going from the supermacro to the sr71 was like a breath of fresh air.

I bought the sr71 fully expecting that I would be returning it, because everyone who did a review mostly listened to classical or jazz, whereas I listen to mostly pop. Also I couldn't picture any difference in sound that's worth $400. I just had to satisfy my curiosity from all that praise the sr71 got. Now, I'm glad I did.

Actually.. While it is great for the likes of me that there are people willing to spend that much on amps... I must ask "why".

Especially... Why even try the PortaPhile V2 when you already have an amp costing twice as much?

You mentioned there are differences, but it probably wouldn't occur me to try it if I already spent that much on the SR-71...

Well by your own words I and having both amps, I would have to say that the SM was defective. I hear differences btween the units but both are very musical and dynamic. I listen to quite a bit of live music and my home setup extremely musical. I enjoy music done well and know what I hear. Again, it would appear that your unit was defective. I beleive it was Xanth that did a reveiw of the SM and appeared to enjoy its musical attributes.

John

I tried it primarily because it has a 2-week money back guarantee. I was looking for a cheaper amp anyway because, as I mentioned earlier, I don't want to carry a $400 amp every day. Also, the benefits of the SR71 is lost if you're listening to it on the train or in a public place. You need a quiet place to hear all that detail. In other words, it wouldn't be efficient to use a $400 amp on the road because you won't hear what you're paying for due to external noise, and in the meanwhile, the amp is subject to heavy abuse unnecessarily.

Now, if the Portaphile V2 is a subset of the SR71-- i.e. having the same sound signature but slightly inferior-- I would return the SR71 immediately because it'd be a waste of money to have 2 amps that sound the same. But the Portaphile V2 is like the SR71 only in terms of neutrality.. in all other aspects the portaphile is different as night and day. BUT unlike the Supermacro V1, I find the Portaphile's improvement in sound to be essential. The supermacro's change in sound is just "different"-- some might call it "better," but to me, it's like changing the EQ on your sound card. The sound is preferential at best.

I just don't get how some people can compare the supermacro V1 with the sr71. To me, they're not even close. Maybe my ears are wired differently or something.

Thanks, I guess this pretty much settles it.

I'll need to think hard how often am I willing to carry an amp outside. If I am mostly going to listen at home, then I might give the SR-71 a more serious thought.

But the Portaphile seems more flexible in that its smaller. Plus, the money saved can cover most of the cost of a new source. My UM2 simply doesn't go with my flash player. The first time I tried on the flash player, I thought I'd broken one of the two!
(there was no music at all... the 2nd time was better, but its still 60% music, 40% noise give or take).

I don't know how the UM2 sounds, but you might want to consider getting a Sennheiser HD580. The 580 is virtually equivalent to the 600 model, which is what Cesar uses when he tests his amp.

If you get a 580, you'd be sure to hear what Cesar is trying to do-- how the amp is supposed to sound. I have Grado SR225 and Ety Er6i and I must say the portaphile sounds best with my HD580.