TTVJ Portable Question

[The Monkey]

Considering this amp. Has anyone heard the DAC version? If so, how is it?

[Voltron]

It sounds really good with the DAC, and I had that version for several weeks on the loaner program and for DanJam. Did you not hear it there? I think I *might* prefer the Pico DAC, but I didn't really do head-to-head comparisons. I think the TTVJ amp is better sounding and on balance would choose it over the Pico. When I bought one, I went with the amp only version because I just don't really use the Pico with DAC too often and for now I have both (well, Dom has the Pico physically) so I could pick that one for laptop usage when needed. I also think the TTVJ handles a wider range of cans with the gain switch and seemingly higher output.

JP heard the amp/dac for awhile on loan, and Vicki and Doug and others heard it at DanJam I think.

[tyrion]

I think there is one with a dac for sale on HF. I like the amp and considered it when I picked the Rx. The build quality of the TTVJ is a bit better than the Rx, at least in terms of the case. I had to send an Rx back as the jacks became loose. I don't recall how the TTVJ compares sound wise to the Rx but I'm guessing it's not a big difference.

[drp]

Haven't listened to the TTVJ's DAC section too much, but what I did listen to sounded more than passable for a laptop office rig or other transportable use. Hard to qualify for a DAC collector....

If it lacks anything in the DAC (say compared to the Pico), it more than makes up for in the amp section; I also prefer the TTVJ's amp section to that of the Pico. Plus, hooked up to an Opus 21 and driving the HF-2s, I'd swear I was listening to a > mid-level home amp. Really seems to have the juice where and when needed. Freq. extension seems good on both ends.

The size/profile of the TTVJ makes is easy to slip it and an iMod (Nano) in my back or shirt pocket. The thumb wheel makes it easy to adjust the volume without it looking like I am tweaking myself (especially given the big grin on my face while listening). Didn't think I would much like the color-changing LED, but starting to really appreciate being able to see the volume setting at a glance. All around, a solid little product.

Buy it for the amp, appreciate it for the added DAC.

[The Monkey]

Right on. Got it for $350 all in.

[STEAXAUCE]

I've been looking at the TTVJ Portable and the ALO Rx. They seem very similar from the product pages. Here's a comparison of the specs:

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The frequency response appears equally good on both.

The maximum output voltage on the TTVJ is listed as 3.29V RMS. ALO lists 7.45V peak-to-peak=5.26V RMS as the maximum voltage output for the Rx in the specs, but "a minimum of 5.25V peak to peak," which is 3.711V RMS, in the product description. Depending on which of these numbers is comparable to the one TTVJ stated, if either of them are, the Rx either has slightly more or substantially more voltage swing than the TTVJ. It may be that the 5.25V peak to peak in the specifications for the Rx is actually supposed to be the RMS value, since 5.25V RMS is almost exactly 7.45V peak to peak. Maximum current is 200mA for the ALO and 100mA for the TTVJ. None of this is really an issue for me personally, as I'll be using it with the JH13.

The output impedance is listed as "less than 1 Ohm" for the Rx and "approximately 2 Ohms" for the TTVJ. The output impedance definitely could be an issue for a JH13 owner, as the JH13 seems to have widely varied (and low) impedance, so that higher output impedance could affect the frequency response. 2 Ohms isn't that high, but it's not zero.

The THD+N spec is exactly the same for both: .004% @ 1V RMS into 24 Ohms.

The broadband noise spec is the same for both: "<10μV RMS, unweighted, integrated over 20Hz - 20kHz"

DC offset is listed as <5 microV for the TTVJ and <3 microV for the ALO.

The input impedance is listed as 10KOhms for the TTVJ and 40KOhms for the Rx. Depending on your source, this could make a difference.

Stated maximum input levels are 5V RMS and 2V RMS for the ALO and TTVJ, respectively.

Channel tracking specification is the same for both. I'm wondering whether or nor these use the same volume control.

The TTVJ has 3 gain settings: +0db (unity), +10db and +20db. The ALO has gain settings of 1.5x and 6x. The ALO's gain switch is internal, and *I believe* the TTVJ's is external.

The dimensions are approximately the same. The sides are rounded on the TTVJ, which I kind of like. I'd expect that to make it more comfortable in my pocket.

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The small differences between the specs of the two are the only differences I can confirm, and specs can be unreliable. If anyone has any other information on the two, particularly on the actual design differences, I'd love to hear about it.

[Duggeh]

Theres also the difference that one is made by ALO. Which is, lets be honest. 10^6 times more important than .1v difference in the voltage swing.

[justin]

rms voltage = peak to peak / 2.82

[STEAXAUCE]

Theres also the difference that one is made by ALO. Which is, lets be honest. 10^6 times more important than .1v difference in the voltage swing.

Um, is that good or bad? I'm new here. So far, I only know you guys hate RSA.

[STEAXAUCE]

Justin, I thought RMS voltage was peak to peak/sqrt(2)?

[justin]

p2p/ 2*sqrt(2)

[STEAXAUCE]

I'm...confused. Lemme figure out what I did wrong with that when I get back. I'm now wondering whether or not I missed a whole lot of physics problems last semester. Wikipedia says RMS for a sine wave is its amplitude divided by sqrt(2). What am I missing?

[justin]

RMS = peak / sqrt(2)

RMS = peak to peak / 2*sqrt(2)

[STEAXAUCE]

Amplitude /= peak to peak. That occurred to me a minute ago while I was away. Thanks Justin.

[The Monkey]

Listening to the TTVJ Portable right now. Setup is iMod-->TTVJ-->JH13. Very preliminary impressions are that it sounds damn good. The JH13s don't need an amp but they sure do like one. Moar bass quantity with the same extension, and without congestion.

Also the iPod is black and the JH13 muddy water blue, so that probably adds to the nice bass. Full impressions after the ALO iMod LOD has burned in for 2 years.

[jinp6301]

Can you check on how the dac sounds when you get a chance?

[The Monkey]

Will do.

And you're not the boss of me.

[kevin gilmore]

The maximum output voltage on the TTVJ is listed as 3.29V RMS. ALO lists 7.45V peak-to-peak=5.26V RMS as ...

The TTVJ portable uses a switcher inside to run the output section at +/- 5 volts

3.29VRMS is 9.2 volts peak to peak which comes about as close as posible to

rail to rail.

Not sure what is inside the ALO, but 7.45 VPP is 2.66 VRMS

[Dusty Chalk]

Also the iPod is black and the JH13 muddy water blue, so that probably adds to the nice bass.

I didn't think blue did anything for extension, but it tightened it up some. I thought you wanted red for sheer quantity. Gold or brown are good, too.