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Tube Phono Equaliser
“Scratch”
Page 4, Connecting & Listening (draft)
Last modified December 27, 2001
This project started as a new phono pre-amplifier for my (old) Thorens TD166mk1 turntable. I built my new UL40-S2 tube amplifier and it did not have a phono pre on-board, therefore I either had to make one or buy one. Looking back to my requirements when I started the project I think things got a little bit out of hands: First because the costs of this projects were much higher than I anticipated, secondly because the results were so much better than I expected for a phono equaliser that I want to hear it sing in the living room with my Clearaudio Champion high-end turntable with Dynavector DV17 cartridge.
This means that I will add two MC step-up transformers to scratch, so that it will be able to amplify MC cartridges too.
As far as sound and musicality is concerned, this project is a big success. Unfortunately I’m not able to take measurements on the RIAA filter myself, but listening to the music I think that both fo classical music and jazz/pop music the Scratch excells in mid range openness with nice treble without any harshness and extended bass.
Having said all these things, let me continue by showing a close range picture of this RIAA network. I’t only a few components, but it makes all the difference between just playing some records and playing records with the right amount of bass, mid0range and treble. Especially with the correct midrange that humans are so sensitive for. The RIAA filter consumes only little floorspace in scratch and I soldered all components to each other in order to minimize possible interference with other components.
I connected Scratch to the main using my homebrew Conradsel power cord.At first I used a power outlet without ground/earth because of the hum. After all the scratch is connected to the earth of the amplifier through the interlinks. The netfilter greatly reduced ticks and other pollution coming from vacuum cleaners and computer monitors.
For the listening session I used the following setup in the study:
Apart from those, I still have my “old” Philips digital amplifier which contains the DAC for the all-digital Philips CD player. But having so much vinyl at hand and such good equipment, listening to CD is not so much fun anymore.
For the first days, I did miss some lower bass power. Therefore I gave it a few days to burn-in the tubes and the capacitors. Thereafter I took my own “reference” recording; Mendelssohn’s Organ Works which is excellent for listening to bass and complex sound. Our clearaudio turntable in the living room loves this kind of music and plays everything with ease. Most turntable/amp combinations have the tendency to sound harsh though. Scratch did not disappoint me, and began to sound better by the day.
Of course it is not fair to compare a $100 Thorens/AT110 combination with a $1750 clearaudio/Dynavector combination. But the Thorens was doing fine.
I understood that the Black Gate capacitors may need more than 2 months to break-in. Fortunately after two days things start to sound OK and after a week I think they are at 95% of their top. The remaining 5% are the icing on the cake.
I did listen to (amongst others):
Scratch has no difficulties whatsoever with the music. Maybe there is still a little dip in the frequency in the mid-frquency area, but this could also be due to the speakers in my study. I may have to cross-check this downstairs on the Elac Dolce Vita speakers. These speakers do have a very flat frequency response .
The treble part sounds good, but there remain little edges if the music is complex and loud. It could very well be that the cartridge used is simply the weakest chain. Hmm, although I’m starting to get used to the idea that Scratch may be simply too good for the current truntable/cartridge combination, I want to listen to it in combination with the Clearaudio first before I give my final judgement. And before I can do that, I will need a pair of step-up transformers.
We like the sound of Sratch so much that we consider to modify scratch in the foreseeable future with two MC step-up transformers (LL9206) of Lundahl.
© Maarten&Annemarie, December 2001