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In the Forum: Melquiades Amplifier
In the Thread: Valve Preamplifier for Macondo/DSET
Post Subject: Yes, it is about my sourcesPosted by anthony on: 4/20/2019
 Romy the Cat wrote:

 
I do not know why Placette does not work in your situation. You do not have enough volume? If it is the case then you might have too low gains in your front end. All my front ends have very high gain: Bidat, Lavry, my phonostage, Passific use have it. The only in Video mode what I drive the things from Oppo then I have no volume and that brought me to new high gain active Placette modules. I do not know what frond end you have; it might be easy to add some gain you your current front end. If it is not discreet circuit in you front-end and has some kind of chip then my lowering a feedback you can always get 6-12db more. If it is not volume but you do not like the Placette sound then I would like to hear more details: what specific you do not like in it. I think I know very well this unit and I might be able to debug the problems. 
 
 


Exactly that, my sources do not play loud enough through the Melquiades or DSET.  Like your OPPO, they only put out about 2V RMS which seems to be the modern standard and I need more.  Can you remember what input voltage DSET needs for maximum volume?  I can measure this, but just need some time.  Some sources these days have less than the nominal 2VRMS output, and my favourite source (which is my dac) I believe will only give a little over 1VRMS (which I need to measure).

The desire for a valve preamp comes solely from one direction:  I am going to build one or two valve phonos to see how they compare to my SS phonos, and if successful it would be nice to box up the phono and preamp into the one chassis (separate power supply of course)...so one box on the shelf rather than one phono box and one preamplifier box.  Of course the valve preamp has to earn its place and in general I am happy with the Placette but it does not have any gain.  It is unlikely that any future sources that I end up with will have high voltage output so it makes sense to me to add a little voltage gain in the preamp rather than fiddling with my sources.  The SS pre that I almost have finished may or may not have enough gain and it may or may not be a successful challenger to the Placette, but only time will tell.  Of course slapping a SS pre in the same box as a valve or SS phono is not a real issue...it can be done.


 Romy the Cat wrote:

  
Still for the configuration of a pram driving passive filters you need a current source with as low output impedance as possible. There is not a lot preamps out there that drive a lot of current with sub 20R impedance. Many contemporary oops preams will do but they not necessary sound acceptable. So, here we go… the game is open… 
  


The SS pre that I am building fits these parameters...and sounds very good in other systems...but the DSET is a very specific load to master and it will be interesting to see how it performs against the Placette.  Like all my audio projects, it has taken a long time to finish and at the time all I wanted was a unity gain linestage and I almost did not start the project because of the 4x (from memory) gain but thought if it did not work out that I could task it as a headphone amplifier.

 Romy the Cat wrote:

If I do play the game of looking for an alternative to Placette preamps then I would look still for discreet SS units like Blowtorch and alike. The active Placette with gain is a controversial inot in my estimation. It is very good but I do feel a difference between the no gain Placette and the gain Placette. It is hard to explain the difference as it is not in realm of sound but rather is a realm of “efforts”.  I have not happy with any tube preams I have heard. 
  
Now we enter the realm of DIY: the idea of making you own preamp. I know absolutely nothing bout SS designs. I made one that was designed for me by a very strong person and it was an honorable nightmare sonically. My tube line stages also were not good but it means nothing, you can me luckier. I would certainly not consider YO186. It is a spectacular tube but very colored, particular in the under-power mode as it is being used in Milq. In the Milq specific application, driving S2 and operating in a very limited range I feel I get the best from YO186 and use the YO186 colorations creatively. I however feel that it is no way a wide range tube and any type 45 tube is WAY more accurate sounding. 
  


Point taken about the YO186 colourations, but I still would like to be able to try it.  The twin output socket arrangement on the DSET is great and can be easily duplicated.

 Romy the Cat wrote:

  
How to get low output impedance of out tubes. Yes, the OPT might help. Paralleling tube and trying the OTL mode might help. To use some low R rube like 6C33C as preamp out tube might be a very interesting direction to go. Another alternative would be to have a voltage gain with tube and to have output no gain SS buffer. There is many options out there but too little time to try all of it…  
   

The 6C33C could certainly drive current, and I have spare OPT's here that I could use to experiment.  If I went with tubes I would like to go DHT in this situation for a few reasons which I will outline in the next paragraph.

 Romy the Cat wrote:
I am not sure why I feel you need a tube preamp. It sounds to me that you need gain not a tube preamp. If you formulate your objective that you need a tube preamp then try to formulate for your why you feel you need tube preamp. The point I make is that any progression in audio navigation should start with formulating a proper question to yourself: 
  
http://www.goodsoundclub.com/Forums/ShowPost.aspx?PostID=432 
  
That is in my view helps to focus on what you need instead of what is possible out there. 
  
This is very interesting thread I  would like to see where it take you.


Motivations!  Yes, the murky world of why we do what we do.  The further I have progressed in this DSET/Macondo project the more personal meaning it has accumulated.  Some people have a mid-life crisis and buy a Porsche or a yacht, some guys quit their high paying desk job to go and build a house in the scrub or the beach or use their hands on some large and introspective projects that bring an ongoing associated sense of relief or calm or achievement.  Well, I have the satisfying professional work plus I am still lucky enough to be hands-on at the farm so I am not suffering so much the urge to quit either nor do I need a tree change to balance my life's ambitions...everything is calm and plain sailing at the moment and has been for some time.  

What started out as a project to "get good sound" and "learn new stuff" has morphed into a little of a meaningless semi-philosophical tangent.  To me, DSET/Macondo is about many things including shunning the modern axioms of convenience and instant gratification and taking the path well trodden.  I am very proud of myself that the first DSET was powered up and is in operation without electrocuting myself or letting out any smoke (other than one potentiometer that went off the end of its track and stuck) and that I got the grounding scheme right first time.  The gear is huge and heavy and imposing and much of it is older than I am and it all uses amplifier topology that went out of fashion before my father was born but at the same time it is also relatively unique and of course "I made it".  To say that "I made it" is not some small factor influencing my thoughts about the valve preamp would be an untruth.

Plus, the valve pre would fit into the general vintage styling of the entire system and of course would be heavy, hot, large, difficult and all the things I have come to love about this project.

But, the sonic reasons remain the same as when I started this project, I want good sound.  At the moment I have a partially finished acoustic system and I am trying to pick the best path forward.  I definitely need more gain but am resolved not to alter the output of my sources but instead to put some gain into the preamplifier.  That is the first hurdle:  loudness.  I would love to build it myself and if possible do it with tubes but if SS is necessary then SS will be used.  If I end up sending my Placette over to Guy to get beefed up like yours Romy then that is what it will be.  At the moment, however, I will need more volume to make meaningful judgments about what I hear.  And of course I need to finish building the horns!

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