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tuyen

DHT preamps

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Let's talk about DHT preamps.   Pros & Cons. 

 

Who uses a DHT preamp in their system?  Do you find they posses any unique sonic qualities over non DHT based designs?

 

cheers!

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LOL.  Shall I just start posting photos of various DHT based preamps?

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LOL.  Shall I just start posting photos of various DHT based preamps?

Some people might not have enough down load data left for this month when you start posting pictures..............

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What do you think Mario? DHT good or bad?

To paraphase others the positives are DHT tubes tend to be more linear as a population because they predate negative feedback.   

 

The negatives are collectability (ie they tend to be expensive) and the joys of arranging a low-noise, controlled impedance heater supply. 

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You will always end up with a heater PSU being more expensive than the rest of the amp. It can sound good that is for sure....HiFi is about excess anyway, isn't it?

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Tuyen,

 

You probably want to engage in the technical benefits or discuss the sound of DHT preamps vs. the other types, which I will oblige later. However, can I begin by simply saying that the advantage of using DHT preamps is the beauty of their sound and the 'varied choice' of using Directly Heated Triode tubes.

 

What I mean by this is that while other manufacturers (eg Audio Research, Cary, Conrad Johnson etc) are stuck with using run of the mill tubes like the 12AX7 & 6922 etc in their preamps (mainly because that is what they know how to do), the few DHT preamp manufacturers out there - have much more exotic output tubes to choose from. Now, we all know that in the world of valves, certain valves have a certain sound and will therefore give a perceived lift in sound quality. For example, the 300B and 2A3 tube types are venerated by valve aficianados and considered to be the pinnacle for tone and naturalness when used in valve power amps. By extrapolation, these tube types should also sound excellent in a preamp circuit.

 

Think about it, if a preamp manufacturer chooses to go down the DHT path there is plethora of ultimate best sounding tubes to chose from. For example, from 300B, 2A3, 101D, 45, 50, PX4, 71A etc ...all beautiful sounding and respected tubes. The non-DHT manufacturers are limited to the smaller not-so-sexy tubes. I do not understand why the other manufacturers are stuck in a rut, either they are not adventurous or skillful enough or that the cost to build a DHT preamp is prohibitive (in terms of marketing and selling them in quantity to make a profit)?

 

At the end of the day would you rather have a 300B/2A3/101D sitting in your fancy preamp ..or a tiny 6922? Of course this is a simplistic view and a well executed circuit is what really matters, but I think the DHT tubes are more ambitious and have greater potential. The 6SN7 output tube is probably the fly in the ointment with the discussion I have presented above, because to me it seems to be an all round competent preamp tube.

 

 

Steve.

Edited by Steve M

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They make good SS amps sound more real and less mechanical.

That is where they have it over the alternatives.

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