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Review: HAD Audiolab Maestral II - Page 2

post #16 of 29
Thread Starter 
Quote:
Originally Posted by mnt522 View Post
 

Very interesting review. Have you tried the amp with any other headphones like HD800, HE-6 or LCD-3?

Thanks

Hi Mate, I tried briefly with the HD800 and the pairing is as great as with the HD600, I think an OTL tube amplifier like this is the way to go with this type of high impedance cans, great musicality.

 

Cheers.

post #17 of 29
Thread Starter 
Quote:
Originally Posted by R Giskard View Post
 

Yugas, I have a question for you mate.

 

What is the exact procedure for turning on this amplifier? I mean, do you plug in the headphones first and then turn it on or do you turn the amplifier on first and then plug in the headphones? 

 

The reason I am asking is because I had a long talk with the owner last year about this and his suggestion was to plug in the headphones after the amplifier has been turned on and operating for several minutes to allow for the DC offset to settle down. Plugging the headphones in this way usually resulted in a high frequency pitch tone coming from the headphones.

 

Hi, I always plug my headphones with all my headphone amplifiers off, I'm not saying it is dangeros plugging the headphone after turning it on, is just an habit.

 

In the Maestrall II case, just my suggestion and the owner suggestion too, plug your headphones before and then turn it on (this is the best way), or just let the amp warm for about 3 minutes, and then plug your headphones.

This is a direct consequence of fluctuations in the supply voltage at start (heating) power tubes and generally

not dangerous phenomenon because it has a very low voltage (a few mV), so not worries, but keep in mind the suggestion :)

 

Cheers,

 

post #18 of 29

Afaik the only risk in waiting to plug them in after the amp is on and has heated for a couple of minutes is that with some tube amp designs (notably those with output transformers and NFB) there's a risk of pushing the amp into oscillation if no load is attached...obviously very bad news.  I always start up my tube amp, make sure the volume's on zero, and after 2 or 3 minutes plug in the headphones, then adjust volume.  Switching them off I follow the reverse procedure:  volume to zero, unplug cans, power off amp.  

post #19 of 29
Quote:
Originally Posted by Xenophon View Post
 

Afaik the only risk in waiting to plug them in after the amp is on and has heated for a couple of minutes is that with some tube amp designs (notably those with output transformers and NFB) there's a risk of pushing the amp into oscillation if no load is attached...obviously very bad news.  I always start up my tube amp, make sure the volume's on zero, and after 2 or 3 minutes plug in the headphones, then adjust volume.  Switching them off I follow the reverse procedure:  volume to zero, unplug cans, power off amp.  

Hello!

 

Yes, that is exactly what I was referring to. Those were the exact instructions that the owner of HAD gave me.

 

However, I don't know if he changed the design since then. I had the very first version of model One on a review here, the very first amp from HAD, and then the model Two which came in it's version 1 form and then subsequently he sent me the production model which was different and better sounding in my opinion. 

 

The one curiosity was his statement that there is no buffer capacitor on the very output and that it's function has been replaced by the sensitivity pot on the back panel. This buffer is the only thing that would stand between the drivers of the headphones and the output tubes and it isn't there. My T1s suffered serious driver damage upon turning on the amp one time. That among other things broke the chain link between HAD and myself.

post #20 of 29

Greetings to all music and headphones lovers!

My name is Drazen, I am owner of HAD Audiolab company and constructor of Maestral series

tube headamps.

I felt it necessary to get involved in this forum to correct some inaccuracies and to offer answers to your questions directly. OTL Single end tube device can not work without output coupling capacitors.

It has a larger capacity, as lower impedance headphones is and how lower frequency we want to reproduce with less loss. So Maestral's  1 and 2  always had and will have an output capacitor.

Although theoretically oscillations in OTL tube device as a result of excessive negative feedback are possible
( because phase shifts at higher frequencies become positive feedback), Maestral's has no oscillations
due to not connecting headphones.

Output coupling capacitor due to changes in the DC voltage at the terminals works as a small rectifier diode until the DC voltage does not settle. Each tubes OTL SE is doing so during power on and off .
When the headphones are connected - this low voltage DC offset from cappacitor due to relatively low
ohm resistance of the headphones quickly discharges to ground. When headphones aren't connected, this DC offset voltage discharges slowly, but always after a minute or two to be zero or near zero....

 

Regards,

Drazen

post #21 of 29

Small correction of my previous post - tube SE OTL is of course possible without

output coupling capacitor, but then we talk about specific design that is irrelevant

to this thread.

post #22 of 29
Nice review, I'm a sucker for tubes! Must be strong lol
post #23 of 29
Thread Starter 
Quote:
Originally Posted by Paulo83 View Post

Nice review, I'm a sucker for tubes! Must be strong lol

Thanks! I'm a tube rolling fan now...It's pretty fun smily_headphones1.gif
post #24 of 29
Thread Starter 

BTW it seems to be an special price of 499 euros until 30th of September for the Maestral II, I think it is a good price :)

post #25 of 29

Wow, that's under £400 (plus shipping) for this amp which is a very good deal. I feel a spend coming on...

 

Quote:

Originally Posted by yugas View Post
 

BTW it seems to be an special price of 499 euros until 30th of September for the Maestral II, I think it is a good price :)

post #26 of 29
Quote:
Originally Posted by yugas View Post
 

BTW it seems to be an special price of 499 euros until 30th of September for the Maestral II, I think it is a good price :)


Used to be 400€ for the Maestral III until it got famous. :P

post #27 of 29

Sad News to report.  We received word today that last night Drazen Markesic passed away.  He was 45 and leaves behind his wife Amelie and son, George.  He was not know to be ill, and his passing comes as a shock to all.   No further information is known at this time.  

post #28 of 29

So sorry to hear this desperately sad and awful news. Drazen made wonderful tube amps and was a true gentlemen with a great sense of humour. 

 

Quote:

Originally Posted by FredSD View Post
 

Sad News to report.  We received word today that last night Drazen Markesic passed away.  He was 45 and leaves behind his wife Amelie and son, George.  He was not know to be ill, and his passing comes as a shock to all.   No further information is known at this time.  

post #29 of 29
Thread Starter 

Very sad new.... and he was so young.

Rest in peace.

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