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In the Forum: Horn-Loaded Speakers
In the Thread: Deep End DIY - Australian take one Macondo.
Post Subject: Melq ConcernsPosted by anthony on: 10/24/2025
Whenever you have a large project such as this you always look back and wish there were some things you did a little bit differently. I have a few minor issues with the physical layout of my versions of the actual Melquiades DSET amplifiers, but also a couple regarding topology, which I will introduce here.
Two channels of Melquiades are single stage SET using 6e6P-DR: one is for the Fundamentals Channel which is a Vitavox S2 in 250Hz tractrix horn; the other for the RAAL Lazy Ribbon HF channel. They are the first amplifier channels in which measured distortion rises, especially the Fundamentals Channel which is less attenuated than the HF channel.
I've never really appreciated the Fundamentals Channel. Before meticulous time alignment of the horn stack I appreciated the channel more, but nowadays it is turned right down and is not really heard. It is not needed for a flat frequency response as the MF and UB horns mesh nicely at about 1kHz, and when turned up I find it brings a harshness to the sound, which is probably that single stage SET under duress. Would it be better to run Fundamentals via a second stage? I am not sure, but I would like to talk to Romy about his thoughts and intentions and results when developing the channel.
The HF Channel and the RAAL ribbon have been very successful, but it's always been the quietest channel, and now with the new preamp and louder Melq tuning it is no longer loud enough for the other channels. For me there has always been a case for a second stage for this amplifier channel and/or a change of tweeter to something a little louder. Under consideration is a DHT second stage just like the MF channel, but probably restrict myself to 2.5V tubes as the filament wiring and transformers are already in place in DSET. Tweeter options are perhaps Fostex T500MK?, the new Vitavox TR32 or even the Tannoy Red, however the latter would possibly require a 6c33c second stage which is a lot more difficult to implement.
I can hear the question now...why change preamplifier if you have to alter your amplifiers to suit? Other than the obvious order of magnitude better sound with the new pre, which is enough of a reason on its own, I already had reservations about the single stage channels and would eventually have experimented with making them dual stage. But there is another huge reason not yet mentioned... Rerurn to Romy the Cat's Site