Advicd Needed on Change from Levinson to Audio Research

Five months later. I have finally have my system sorted.

The SP-6B refurb came back. The phono section sounds unbelievably good. Very punchy when needed, very dynamic and rich sounding. Definitely a keeper.

I have listened with these power amps: CJ CL62, Class D (Apollon), and my old Levinson #27. Speakers are Revel f208. These are somewhat power hungry (for better sound)

After much listening, my old #27 is clearly the choice. It has the ability to keep up with the dynamics. The CL62 is underpowered for the f208 speakers. It sounded OK, but not as good as the #27. The Class D will be a very good backup for the aging #27.

One problem was what to do about the cable mismatch. The SP-6B is unbalanced. All my downstream gear is fully balanced. The SP-6B feeds a balanced analog EQ. Then the EQ feeds the power amp. I made a cable to transition from RCA at the 6B main output to XLR at EQ input. Pins 1 and 3 are shorted together. This works great. No hiss or rumble. No ground loop issue. I have tried transformer and active devices to transition from RCA to XLR, but these inevitably led to more noise, more hum and a conversion from -10dBV to +4 dBu, which is a gain of 4 or 12 dB. This is too much gain for my system. I am going to make my own 1:1 converter and see how that works, but I know now that my simple cable is not adding to the noise.

The tube preamp and beefy solid state power amplifier is definitely the right move for me.

Thanks for all your great suggestions!

pwerahera

Good to read that you are still enjoying a classic Cary/ML and Thiel combination.

Happy Listening!

@pwerahera 

Hey, thanks for the encouragement.

I really want to try the SP6. Although it is not balanced, I will use an RCA->XLR cable to the first downstream component.The rest of the cabling is XLR,  including the line level to the power amp. Those cables you saw are XLR. I have no noise issues and no IR drop because of the long 12 gaoge speaker cables.

I have built and tested my RCA->Male XLR cable. There is inaudible noise (-100dB) from power related noise, ground loops, or pick up. I use a spectrum analyzer to detect these issues. Doesn't seem to be an issue, but I will definitely test again after everything is hooked up, since my test bench is not in the system.

I will have the  SSP6 back from AR in about 6 weeks or less. Can't wait.

I have Mark Levinson 23.5 connected to Thiel 3.6 speakers. My current preamp is Cary Audio SLP03. I am very pleased with this combination. My phono preamp is Audio Research PH5 and I also have Audio Research DAC #3. These are all tube gear. So I don’t see how you can go wrong replacing your SS preamp with a tube preamp.

I am not familiar with AR SP-6B, but I suggest you find a tube preamp with balanced XLR output since you have > 8ft cables running from your preamp to the amp (from your system photos). I also had a VTL 2.5 preamp before Cary and that also worked very well. Hope this helps.

Thanks for the info. I've looked at the D-76. It looks really complicated and expensive to maintain. I can't imagine the trouble involved in biasing all those tubes.

What exactly will prevent me from obtaining the best performance from the sp6/Reference 75 combo?

I understand unbalanced vs balanced. I regularly make my own single ended to balanced cables, both male and female. I also have a transformer for one line.

The remaining parts of my system are balanced. All I would need is to make conversion cables for one SP-6 input (line level, the phono is already unbalanced) and the SP6 output. After that, I'm all balanced.

I don't consider the unbal/bal issue a problem. Juat recently I had a Paragon System E tube preamplifier (ca 1977, so contemporary with the SP6) as my preamp. I connected as I described above. It worked well. Dead quiet at normal listening level. No ground loops.

What am I missing?

I'd look for a D75/76 amp instead. That would match better with the SP6B. I have a SP6/D75 pair and am pleased with the sound quality.

The SP6B and the Ref 75 are from completely different eras and you're not likely to get the best performance from either by using them together. In particular, the 6B is single-ended while the Reference 75 is balanced. The SP6 is very colored by modern standards, although of course it can still sound sweet.