[Makiah S]

RAAL-requisite’s all new standalone headphone amp the PDT-1a features a dedicated OTL circuit design built for traditional non-electrostatic headphones. This top of the line amp delivers uncompromising performance for planar magnetic and dynamic headphones, price is set around $2,000.


Features
6N6P Driver Tubes and a 6AS7 Power Tube
Frequency Response: 10Hz-100kHz -3db
THD: <1%
S/N: 80dB
Power: 245mW @50ohms / 180mW @600ohms
With Center Tap AC Heaters for low noise

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[Loftprojection]

Any idea on price? Looks a bit like a Woo WA6 or Icon HP8, will be very interesting to read about it's sound.

 

[Makiah S]

Any idea on price? Looks a bit like a Woo WA6 or Icon HP8, will be very interesting to read about it's sound.

About 2,000

I've got one in my home at the moment and as far as the sound goes and has that big beautiful tone and body you expect from an OTL but with some absolutely insane texture and holographic staging!!

I'm playing around a bit with some tube rolling now before I make a more thorough write up, but right out of the box it's one of my favorite otls that I've heard.

I like it quite a bit more than the crack and crack with speedball combinations that I've listened to over the years

 

[G8torbyte]

I've got one in my home at the moment and as far as the sound goes and has that big beautiful tone and body you expect from an OTL but with some absolutely insane texture and holographic staging!!

I'm playing around a bit with some tube rolling now before I make a more thorough write up, but right out of the box it's one of my favorite otls that I've heard.

I like it quite a bit more than the crack and crack with speedball combinations that I've listened to over the years

Any further impressions or tube recommendations? I just purchased an open-box one from HeadAmp and looking forward to trying it out on my ZMF Atriums which have amazing holographic staging. I'll follow-up with my thoughts after it comes in. Thanks.

 

[Makiah S]

Any further impressions or tube recommendations? I just purchased an open-box one from HeadAmp and looking forward to trying it out on my ZMF Atriums which have amazing holographic staging. I'll follow-up with my thoughts after it comes in. Thanks.

Looking forward to hearing your thoughts!

 

[G8torbyte]

Looking forward to hearing your thoughts!

Sure, I think it is due for delivery today. There are no formal reviews I could find on the amp other than some initial comments from CanJam.
Did you keep the one you were trying out?

 

[G8torbyte]

@Makiah S , received it this afternoon.
Thank you for the excellent packing and quick shipment from HeadAmp. All arrived with no issues and thanks for packing the tubes separately.
This is my first non-hybrid tube amp so my comparisons are limited. Here's a few quick assessments after a few hours:

First off, I like the solid build quality and love the size/smoothness of the volume knob. I've read that toroidal transformers do well in reducing any background noise (hiss/hum or crackling) and I'm happy to say it is working nicely on the PDT-1a. I don't hear anything even when dialing up the volume after pausing the signal.
The ZMF Atrium and Fostex TR-X00 sound fantastic with the spaciousness and holographic staging. The sound is full across the low-to-high ranges and loud enough for me at around 10 o'clock on the dial. Also did a quick check with the Sennheiser Jubilees and 80-Ohm DT-770 Beyerdynamics and they sound great too.

So safe to say dynamics respond very well, but my planars on the other hand, sounded weak and anemic on this amp. The LCD-2C seemed blunted/kind of muffled. Even worse on the Ether CX and the Aeons and they became distorted as I approached 50% on the volume. Maybe it's my planar models that do not work well on it and perhaps it could do better with more sensitive planars? I'm not surprised since I notice the same weakness when I play my planars with hybrid tube amps. They do best with solid-state. So at this point I'm enjoying it with my dynamics. Not so much for planars.

It is a space-heater! I knew these type of amps radiate heat but whoa. It is too hot to handle on the sides and the tubes are cookin'! I'll need to re-arrange my desk for space and ventilation. It'll be good for the winter season to warm a room

UPDATE: I did have one other set of planars that responded better than the LCD-2C and DCA's I tried on the PDT-1a: Monoprice M570. It has the same drivers as the Sendy Aiva and a Sivga model with a lower 32 Ohm impedance so that could be the reason. Still not as magical as the dynamics that pair much better on it.

 

[GU1DO]

Any idea what is the volume controller in this amp ?
hopefully not an alps pot

 

[bagwell359]

Any idea what is the volume controller in this amp ?
hopefully not an alps pot

Whats wrong with Alps? They make a large array of pots. Some of extremely high quality. You must be referring to a low end one. Please share.

 

[G8torbyte]

I may be one of a very few using this amp so far. Sorry I cannot comment technically on the volume potentiometer. I don't have much insight on the electronics.
To me it has a smooth response. Physically the knob and turning resistance is fine and works well in the few months I've been using. As mentioned earlier I'm impressed with the silent background and it brings out the best in dynamics. Planar headphones may be hit or miss. It did not play very well with my planars. Recently I purchased a Geshelli Labs JNOG2 DAC (w/AKM 4493 chip) to feed this amp and the synergy to my ZMF Atrium is excellent.