Rhea Noise

"The all tube Phonopreamps were not designed for low output MC cartridges. As a fact, this technology is not the right one for use in Phono stages."

I'm sure Jim White of Aesthetix would have a different opinion here. And there are a number of Aesthetix Io users here who have reported excellent success with low output MCs, in particular, the 0.25mv output Koetsus.

I understand the "pain" people have with the Calypso and Rhea. These units seem to be very sensitive to less-than-optimal tubes. All you had to do is read the Calypso review here by Jadem6 and you understand the effort it takes to get these units to perform to impressive levels of musicality.

I run with the 80db gain Aesthetix Io for both Koetsu Rosewood Signature and Clearaudio Accurate. These are both 0.6mv output which work mighty fine with the gain settings at 62db or 68db. I try to set the gain so that I have maximum loudness (mid-high 90 db levels) with the volume control (Aesthetix Callisto Sig) at 2 o'clock or so. In between tracks, at such a high level, I can just barely hear any kind of noise from the seating position. However, as I have reported on other Aesthetix threads here, I have only been able to find 12ax7 tubes from Ei for the first input stage which gives me this very low level of noise. I would love to find an ultra quiet pair of Telefunken or Mullards for this stage. The Sovteks are very quiet in the Io but they simply are far too fatiguing than these other brands. Perhaps you can try the Ei tubes here. They are only $10 so it's worth a try.

John

Once again Thanks for your feedback.. I recently spoke with Mike from Aesthetix. After some tube "gyrations" he concluded the tubes were bad at V 1/2 on both channels. He is burning in a new set for me as I write this. Since I mounted the Shelter 90x, I had to set the gain at 565db using the balance out which increases gain to 62db. The "tube rush" was not typical. This sounded like a LOUD constant wind. It was loud enough that non stereo listeners asked me "what is that noise" Anyway I compliment the tech support from Aesthetix, and we'll see if these different tubes are quieter. Once again thanks for your feedback. I learn so much from the posts.

Like most Rhea owners in this forum I too have had tube issues since the day I purchased it; however, I recently purchased a VTV tube characterizer that solved my problems. I have been able to go through old tubes and find nice matched pairs that work in V1/V2. The VTV immediately screens out noisy or microphonic tubes.

I also learned some things from the good folks at Aesthetix that can save you money.

V1/V2 require longplates which are expensive if you want NOS matched, balanced, quiet non microphonic. But it was explained to me that V1R/V2R work as a pair that needs to be matched to V1L/V2L. For example assume that V1R is 100/100 and V2R is 90/90. These two tubes could be matched with V1L at 98/92 and V2L at 92/98. If you add the gain you get 95 for each of the four triodes which is what you want. Remember V1R + V2R = V1L + V2L

I've also found you don't need to match the gain perfectly as in my example but just get it as close as your ear can tell. The tubes don't need to be perfectly balanced either but probably should be within 10%. They key is that they not be noisy. Nosiy tubes sound like wind and it's not tube rush because it varies in volume intensity. I have found that tubes that sounded slightly microphonic can work well too. More microphonic ones can sometimes be helped with a Herbies damper but really microphonic tubes ring when I touch the chassis.

Having said all that the Sovtek LPS are the quietest tubes I've tested so far. I got lucky with NOS tubes. I found some NOS early 50's Philips longplates that tested absolutely perfect as well as a few pairs of perfect Mullard 10M's, one pair of which is in V3 and the other in my Calypso. None of these NOS tubes were more quiet than the Sovteks but they were just about equal. I have some matched Brimar CV4004's in V4 and Philips 7308 SQ in V5.

I've had this setup for about a week now and I'm still pinching myself. After six months of one tube hassle after another some of which were of my own doing, I'm now in audio nirvana. The Philips tubes are 3D like. This is not the same Rhea I purchased. It sounds awesome now as opposed to great when it was working before. The noise is not an issue and I'm using an .24mv Airy at 68db balanced. It also works at 75db rca but it pops at 75db balanced. I'm not sure whether it's supposed to work at 75db balanced or not.

I wish I'd bought the VTV right away. It's expensive but it will pay for itself in the long.

My Rhea is extremely quiet and sounds wonderful with a 0.5 mV cartridge. It is hard for me to understand why there is so much negative comment on this thread about this fine phono stage. Are some of you guys trying to run sub 0.1 mV carts on your Rheas? Why? What advantages do they provide that 0.1 to 0.5 mV carts don't provide? This super low ouput stuff makes me wonder a bit only because then the limiting factor has to be the arm/table and phono pre. I mean I understand the pursuit of excellence here but I have never been convinced that a super low output cart is advantageous.

Something that everyone here needs to understand is that whenever you use a pure tube signal path as a gain source for low output MC cartridges, there will be noise compared to either a fet/tube hybrid gain stage or a pure SS gain stage. The tradeoff for some added noise IMO is a much more live sounding phono stage that doesn't sound flat and two dimensional like its SS brethern. It is imperative that you buy tubes that are graded for noise by a competent dealer such as RAM labs or Kevin Deal or in my case, Michael Elliott of Alta Vista. I use the Counterpoint SA-2 MC pre-preamp and it is pure tube including the rectifier and voltage regulation. I buy the highest grade 6922 tubes that Michael Elliot sells for the SA-2. Only 2 out of 100 tubes makes this cut which is why you pay a premium for them. Buying expensive "super" tubes such as Amperex, Telefunken, etc. which are not graded for noise is a pig-in-a-poke purchase. It doesen't matter how "great" they are if they are noisey.