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In the Forum: Melquiades Amplifier
In the Thread: Valve Preamplifier for Macondo/DSET
Post Subject: Valve Preamplifier for Macondo/DSETPosted by anthony on: 4/19/2019
Hi Romy,
Just thinking out loud here, but I have been listening to my mono DSET/Macondo for quite a while now and recently changed back to my old acoustic system so that I could poke around in the DSET innards for a little while. The old system (in stereo) seems incompetent in comparison to the mono DSET/Melquiades. In particular I've really been appreciating the YO186 tube in the midrange horn, and although I have had a 45 in there for a little while the Stalin era Russian tube is really something special. I remember reading on this site about your thoughts of getting some of the YO186 tubes traits as low in frequency as the Upperbass Channel, and from what I have heard I would tend to agree, or at least I think it may be worth trying.
Also on my agenda is to build a valve based LCR phono and for the past few days I have been thinking about possibly going the whole hog and incorporating a valve preamplifier as well. My current sources do not have the voltage output to directly drive my DSET/Macondo to satisfying volume so I am going to need some kind of preamplification, preferably with about x3 or maybe x4 amplification...the Placette will not work as a linestage alone. Although not yet measured, the DSET will probably prove a complex and relatively low impedance load for a preamplifier so the pre will need a low output impedance, preferably 20R or less. Difficult with valves but not impossible, especially if using an output transformer.
Which brings me to my current thought bubble...a low gain pre-amp with perhaps a YO186 as output tube, or even an interchangeable arrangement with both 2.5V and 4V tubes as is currently in the DSET, which would allow using perhaps a 45 in the pre and the YO186 in the DSET or vice versa. There are certainly concerns about having too much of a good thing and messing with what the DSET is able to achieve in combination with Macondo, but perhaps this may be a way of getting the YO186 traits into the entire frequency range, not just the upper mids.
I also have some memory about reading on here about you experimenting with valve preamplification in the early or pre-Melquiades days but being unable to find satisfaction. Technically, I like the idea of good SS circuitry to handle the pre-amplification duties, and it seems as though Guy Hammels recent introduction of gain to your Placette Linestage has been successful, so that is an option also for my unit. Shortly I will have a very good Class A SS Pre finished that has some gain and will use a high quality volume control, so perhaps it will make the Placette redundant. But it would be nice to do it all with valves..
Regards,
Anthony
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