Trends Audio NEW Headphone Tube AMP: UPDATE W/ Photos - Page 2

PHOTOS!

Ok folks I have a small shipment of these in stock now. Here are some photos. I only have had a few hours to mess around with it but I can say that I really like it. I have a feeling it in improve a lot once it gets burned in. Here are some things to keep in mind. Set the bias after a few hours, I would do this as you burn it in several times. Mine was off right off the bat. See instructions and photo below.

86 the stock tube! I swapped it our with a Bugle Boy and it made a pretty significant improvement.

I do not want to make any lengthy impression statements as it only has a few hours on it. I am certain that this will change once it gets some time on it, however so far the amp seems to really favor harder to drive higher impedance phones. My favorite headphone with this is the AKG 702, and 701s, in fact it drives the hell out of these phones. I also found that the best interconnect was the JenaLabs trio plus and fugue, by far as it tamed the tightness of the amp. I am hoping that it relaxes (I am sure it will) as it burns in. You do not want to use a silver IC with this amp, at least my new one does not.
To set the Bias;

Since each tube may derivate a bit in parameters, especially from different series, it
needs to re-tune the DC bias voltages to guarantee the machine is working in the best
point and performing the best sound quality.
There are two blue precise adjustable potentiometers (R3, R13) for tuning the DC bias
voltage of each channel. The DC bias has been tuned in factory. But after run-in for a
period or changed another tube, it would be deviated that the fine-tuning is needed.
Before you tune these, you need a screwdriver (take off the case), a small screwdriver
(turn the screw of the potentiometer) and a (digital) multi-meter to detect the DC bias
voltage.

1. Use screwdriver to take out the two upper level screws in the front panel &
another two screws in the back panel. Then, open the upper case.

2. Power ON the machine with no audio signal input.

3. Wait at least 5 minutes for the machine to run in.

4. Use the multi-meter to detect the DC voltage between the test point A(L) [red] in
the PCB & the GND [black] (e.g. the ring of the power switch or the outer ring of
those RCA sockets) of the LEFT channel.

5. Turn the screw on the top of the R3 potentiometer by a small screwdriver
clockwise or anticlockwise until the voltage as close as to +16.5V.

6. Then, repeat step 4 and 5 for the RIGHT channel by changing the test point to
A(R) [red] and turning the screw on the top of the R13 potentiometer.

7. Power OFF the amplifier.

8. Cover back the upper case and tighten the screws.



Tube Rolling;

This amp should be a lot of fun to tube roll with.

Trends PA-10 supports two major tube series: (1) 6DJ8, 6922, 6N11, 6H23n, ECC88,
E88CC, etc…, and (2) 12AU7, 5963, 5814, ECC82, etc… If you change the tube
within the same series, it needs to re-tune the DC bias voltages ONLY. If you change
the tube from another series, it needs both to re-tune the DC bias voltages and re-set
the jumpers.

David at Trends also told us;

DIYers can also try to upgrade the coupling caps of audio output (C3, C6 - block 10uF caps) and headphone output (C4, C7 - tank 1000uF caps). The power filtering caps C2, C5 can also be upgraded.

For the driving of low impedance base speaker, it should be the responsibility of the power amplifier. Trends PA-10 cannot help much on this. But, for driving the power amplifiers, PA-10 should perform good, even in low-bass. This can be experienced by working PA-10 with our TA-10 as power amplifier. The full range of sound is improve significantly including the low-bass. You can also try this with other power amplifiers. This is because PA-10 is class-A tube amplification and using MOSFET as the output buffer to guarantee the driving power and impedance compatible with the power amplifiers.

So that makes for a nice bonus.

Anyhow I am real happy to have this wonderful affordable versatile small tube headphone amp in the mix.

Please report back here with your impressions and tubes that you have tried.

Ken

Reporting back after a few days of playing burn in and the amp has begun to really smooth out nicely. There was a slight edge and frowardness to it out of the box, now there is a more relaxed tone. I am pretty amazed at how detailed the little amp is. I was using different sources and found that with my D25 its a wonderful match.

Ken

Its a mini (3.5mm) plug. mine is flat out fantastic, for the $$ its tops. I love this thing.

VS the Woo Audio WA6 I have its not quite all that but then again my WA6 was $1200.

Ken

Vinnie is reccomending JJ tubes, has anyone tried these?

On the Power supply, no I have not have a chance to check into any mods yet. But it would be killer to run this off a SLA battery (24V)

Ken