tuyen Posted November 29, 2013 Share Posted November 29, 2013 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! 1 Link to comment Share on other sites More sharing options...
Upfront Posted November 29, 2013 Share Posted November 29, 2013 Ooooo! Interesting! Link to comment Share on other sites More sharing options...
tuyen Posted November 29, 2013 Author Share Posted November 29, 2013 LOL. Shall I just start posting photos of various DHT based preamps? Link to comment Share on other sites More sharing options...
Once was an audiophile Posted November 29, 2013 Share Posted November 29, 2013 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.............. Link to comment Share on other sites More sharing options...
Upfront Posted November 29, 2013 Share Posted November 29, 2013 What do you think Mario? DHT good or bad? Link to comment Share on other sites More sharing options...
thoglette Posted November 29, 2013 Share Posted November 29, 2013 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. Link to comment Share on other sites More sharing options...
Decky Posted November 29, 2013 Share Posted November 29, 2013 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? Link to comment Share on other sites More sharing options...
Steve M Posted November 29, 2013 Share Posted November 29, 2013 (edited) 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 November 29, 2013 by Steve M 1 Link to comment Share on other sites More sharing options...
Once was an audiophile Posted November 29, 2013 Share Posted November 29, 2013 What do you think Mario? DHT good or bad? It got valves must be great 1 Link to comment Share on other sites More sharing options...
THOMO Posted November 29, 2013 Share Posted November 29, 2013 They make good SS amps sound more real and less mechanical. That is where they have it over the alternatives. Link to comment Share on other sites More sharing options...
Decky Posted November 29, 2013 Share Posted November 29, 2013 They make good SS amps sound more real and less mechanical. That is where they have it over the alternatives. Interesting choice of words for someone who owns a gainclone amp Link to comment Share on other sites More sharing options...
Guest guru Posted November 29, 2013 Share Posted November 29, 2013 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. I think you are right about it being a simplistic view but good luck with the passion, that's what gets results. Link to comment Share on other sites More sharing options...
Bronal Posted November 29, 2013 Share Posted November 29, 2013 (edited) I notice no one has owned up to having a DHT preamp, so I will. I have a Tram 2, which is not only DHT but also OTL. I use EML 45s in mine. I will say off the bat that it's the best preamp I've ever heard. The soundstaging is sensationally holographic, enormous bass, very transparent etc. I've heard it in Decky's system driving SGR CX4Fs and IMO it sounds better than his Audio GD (but he wouldn't agree with me). It's also very quiet. The drawback? The bias on one channel of mine drifts after a few weeks and has to be reset. Not big job, technically speaking, but beyond me. I know Nada has one as well so I'm hoping he'll chime in on this. Edited November 29, 2013 by bronal Link to comment Share on other sites More sharing options...
Decky Posted November 29, 2013 Share Posted November 29, 2013 (edited) . I've heard it in Decky's system driving SGR CXR4s and IMO it sounds better than his Audio GD (but he wouldn't agree with me). That is what I said - Tram is the best preamp that I've heard with CX4Fs. Also to add - it is the most "solid state sounding" tube preamp that I have ever heard. The temperature drift is a curse but not a big one. Tram was never designed to be a plug'n'play audio product anyway. Edited November 29, 2013 by Decky Link to comment Share on other sites More sharing options...
tuyen Posted November 29, 2013 Author Share Posted November 29, 2013 What do you mean by the most "solid state sounding" tube preamp? As in 'accurate' and linear/direct sounding? Link to comment Share on other sites More sharing options...
tuyen Posted November 29, 2013 Author Share Posted November 29, 2013 The Tram2 with EML45 must have an extremely good base design (and especially after extensive mods), as it is what Lansche Plasma Guy uses on his system. Said by few to be one of best hifi systems in Australia, even possibly worldwide Link to comment Share on other sites More sharing options...
tuyen Posted November 29, 2013 Author Share Posted November 29, 2013 What about 112a or type 26 / 226 / UX-226 / CX-326 dht based preamps? Anyone with any experience with them? Rod Coleman filament regulators seem like the way to go to keep hum/noise down? is tube or solid state power rectification optimal for DHT preamps? transformer or capacitor coupled? Link to comment Share on other sites More sharing options...
tuyen Posted November 29, 2013 Author Share Posted November 29, 2013 I like the look of something like this Link to comment Share on other sites More sharing options...
Guest guru Posted November 29, 2013 Share Posted November 29, 2013 I like the look of something like this You want to be quick with jumping on something like this as tango ceased production in September this year and the ebay prices have soared as a result. Link to comment Share on other sites More sharing options...
Bronal Posted November 29, 2013 Share Posted November 29, 2013 (edited) What do you mean by the most "solid state sounding" tube preamp? As in 'accurate' and linear/direct sounding? I think what Decky means is that it doesn't sound like a valve job. It sounds like itself - I haven't heard another preamp that sounds like it. I forgot to mention it is extremely fast. PS: if you want to have a lend of mine, let me know. Edited November 29, 2013 by bronal Link to comment Share on other sites More sharing options...
gamve Posted November 29, 2013 Share Posted November 29, 2013 The Tram2 with EML45 must have an extremely good base design (and especially after extensive mods), as it is what Lansche Plasma Guy uses on his system. Said by few to be one of best hifi systems in Australia, even possibly worldwide There does not seem to be a plethora of DHT preamps available commercially that are even close to affordable. The Tram2 seems to be a popular affordable kit until you realize that to get it to perform you need to spend well over double of the price of the kit to get the heaters quiet. I saw a Melody unit sell on Ebay last week that used I think it was 6SN7's and a 101D. I looked at reviews for this unit that said it was dead quite. Then I saw the price tag when they were selling new....gulp nearly 4K. Tuyen, do you have some links for current available units? Link to comment Share on other sites More sharing options...
THOMO Posted November 30, 2013 Share Posted November 30, 2013 (edited) I think what Decky means is that it doesn't sound like a valve job. It sounds like itself - I haven't heard another preamp that sounds like it. I forgot to mention it is extremely fast. PS: if you want to have a lend of mine, let me know. All the DHT preamps I have heard sound very fast. I prefer the transformer coupled ones though. For one thing they have massive and precise soundstaging.Even the cheapish Ming Da MC 2A3. Many people will also find their timbre and tonality beguiling. The Tram is a bit cold and ordinary by comparison.A very good sounding preamp all the same. Edited November 30, 2013 by THOMO Link to comment Share on other sites More sharing options...
kramered Posted November 30, 2013 Share Posted November 30, 2013 I'll be receiving one of Mick Maloney's new DHT creations in the next week or so. Some who have heard it say it's sublime. I will report once in situ. Cheers, EK Link to comment Share on other sites More sharing options...
Decky Posted November 30, 2013 Share Posted November 30, 2013 What do you mean by the most "solid state sounding" tube preamp? As in 'accurate' and linear/direct sounding? We are dealing here with subjective perceptions of the sound so I have to be very careful. I mean: open, transparent, clear, without any perceived rolled-off "sweetness" or "(un)natural timber" (whatever that means?). Whether it is accurate and precise - most likely - never measured it, and that would be the only way to determine that quality. In addition it sound powerful and creates a beautiful 3D sound stage that exceeds the size of my room. Now I can see ZB preparing itself to say how that is the consequence of excessive 2nd order distortion and it is artificial and not real - but hey - what is "real " in this world. Do you think that is air that you breathe now? 1 Link to comment Share on other sites More sharing options...
henry218 Posted November 30, 2013 Share Posted November 30, 2013 it is morpheus,... unless ... are we in matrix now???? Link to comment Share on other sites More sharing options...
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