You should definitely consider the Herron. I AB'd it against the aesthetix rhea signature and it was no contest. The Herron was far more open and natural sounding.
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I own the Herron and have owned the Rhea at the same time. I saw what I thought was a good deal and bought the Rhea out of curiosity. It took while to figure what tubes to put in it to get it to be transparent which it wasnt with stock tubes. I found that the 6DJ8 was the key tube to obtain the voicing I was looking for with a Telefunken being the preferred tube. For the other tubes (v1-v4), I found two different combinations that worked well. The first is all Telefunken and the second is vintage EIs in v1&v2 with GE black plate 5751s in v3& v4. I liked what I heard enough to buy an Aesthetix IO. I sold off the Rhea once I had the IO but regret doing so. The Herron sits idle these days.
The comparisons mentioned above were made between the Herron and Rhea, not the IO. The Rhea was a standard, not the signature version. The point I was trying to make is the tube compliment plays an important role in what your get out of the Rhea, more than the Herron in my experience.
As for IO tubes, I use all Tele's for the 12AX7's and the 6DJ8. The 6SN7's are Tung Sol. In the power supply, there are Russian 12AX7's and until recently Mullard EL34 XF2's. The Mullards have gone south so have been experimenting with different tubes in that position. One other thing to note about the IO. Mine started life as a signature. I replaced the coupling caps with Duelund Cast coppers and the loading resistors with Nude Vishays. I still need to deal with the output caps which are still stock.
Well its been approx. 3 days (9-12 hrs. ) of listening . Its amazing how new tubes could make such a significant difference. The top end on my RS 1-Bs is more delicate and shimmering and yet the mid-range and bass has much more meat on the bone then before. Enjoying the new tubes and a big endorsement to Andy Bowman of Vintage Tube Service. Now I need to think of re-tubing my Aesthetic Calypso!!
Sbrown, Changing the output coupling caps in my Janus made a profound difference in sound. I happened to have some 2uF polystyrene film and foils in my stash, and I used those.
How did you find space to fit the Dueland capacitors in the Io? Unless it affords a lot more room than does the Janus, I would doubt that they fit. I used 300V Vcaps in the Janus. They're only a little larger than the stock polypropylenes.
Sbrown just to clarify the rhea I AB'd against the Herron had a premium Jim mcshane tubeset in it. The Herron had telefunkens in it. 3 of us present all preferred the Herron. I'm a little baffled with your experience as it is so different than ours. Was yours the latest Herron? Did it have good tubes in it?
Jim McShane's tube selections for the Rhea are:
(4) "Mullard" reissue long plate 12AX7's
(4) Sovtek 12AX7LPS
(2) Genelex reissue 6922EH
The big deal is that Jim goes through hundreds of tubes to get especially low-noise sets. Unfortunately, this means he rarely has sets to offer these days because they have become popular with Rhea owners. I'm on the waiting list for a set.
There's some nice synergy at work here, that other brand combinations of new-production don't seem to achieve. Call it "magic" if you like.
Sorry for the delay in getting back to this thread.
Lew, the IO has a lot more space around the coupling caps than does the smaller Rhea or Janus. That's part of the reason I haven't changed the output caps in the IO as I don't have the real estate to put in the pop can sized Duelunds. I'll probably end up with Mundorf silver/gold oils there. What caps did you use in your Janus?
Analogluvr, no my Herron is the VTPH-1 while the Rhea was a standard non-signature. When Keith voiced the VTPH-1, he used Russian tubes so they work better there than with the Rhea. I remembered I tried NOS tubes with Herron and they didn't make that big of a difference. I don't recall what brand of tubes I tried but I have Tele's, Bugle Boys, RCA's and EI's on hand. Overall, the sound quality of the small signal Russian tubes are crap IMO.
The Rhea however (and the IO for that matter) is far more sensitive to tubes and can sound horrible or great depending on what tubes are used. Had I heard the Rhea with only Russian tubes, I would have never liked it enough to go further along that path. If you had swapped tubes between the Rhea and Herron and used a decent 6922 I think your comparison might have come out much closer. You might have still preferred the Herron but you would have gotten a taste of what the Aesthetix brings to the table.
I don't blame you for missing the answers to your questions in reading my rather dense post. The Janus uses only two capacitor values in the coupling applications: 0.22uF and 2.0uF. I replaced the two 0.22uF caps used in both the line stage and phono stage sections with 300V-rated Vcaps (requires four capacitors, total). The choice of 300V rating was determined for me by the fact that they are only a bit larger than the OEM polypropylenes, whereas the 630V-rated Vcaps are quite a bit fatter and longer. I replaced all of the six 2.0uF metalized polypropylene film caps with 2.0uF polystyrene film and foil capacitors. The latter are a bit larger in diameter than the originals but they do fit. I changed nothing else; the tubes are still the OEM ones. The transformation in sound was quite remarkable, more obvious than expected.
I do also have a new tube set from Jim McShane, but I have not installed them as I see no reason yet to do away with the OEM tubes.
The 0.22uF caps are coupling caps and the 2.0uF are output caps. In the signature series, the output caps went from 2.0uF to 4.0uF so they are a load to fit in. I have 4 per side to deal with in the IO and not much room.
I've been curious on how the Vcap coppers compare to the Duelunds. At somepoint, I may replace the 1st stage coupling to the coppers to find out. It had a teflon cap in that position to begin with.
One thing that has not yet been addressed in this thread is impedance compatibility. If the OP is using the MC601 preamp listed in his system description, and plans to connect the phono stage to any of the preamp's inputs other than the unbalanced "tuner" and "aux" inputs (which have 50K input impedances), there may be issues with most of the phono stages that have been mentioned.
The input impedance of the MC601's balanced input does not appear to be specified. And the input impedances of the unbalanced inputs other than the two I mentioned above are only 10K. I'm pretty certain that a 10K load would be decidedly non-optimal for the Rhea and the Herron, and possibly also for the Allnic. And ARC specifies for the PH7 a recommended load of 50K to 100K, with 10K indicated as "minimum."
If the OP's intention is to connect the phono stage to the unbalanced tuner or aux inputs of the MC601, however, there won't be an impedance compatibility issue with any of these phono stages.
Good point, Al.
Just found this info from the S'phile review of the Rhea:
"The preamp's output impedance was a low 110 ohms at 1kHz from the balanced jacks, this rising inconsequentially to 156 ohms at 20kHz but, more significantly, to 3846 ohms at 20Hz. This rise at low frequencies is due to the limited size of the coupling capacitors and implies that the Rhea must be used with a line stage having an input impedance of at least 30k ohms if the bass is not to sound lightweight. The output impedance from the unbalanced RCA jacks was a high 2k ohms across most of the audioband, but as this rose a relatively small amount at 20Hz, to 3.05k ohms, the preamp's tonal balance will be less affected by the line stage having a lowish input impedance."
So to those who own the Signature version, there is a logical reason why it would have a superior bass response compared to the standard Rhea. This is an easy upgrade, however. The Sig version should drive 10K ohms ok though.
Sbrown, It's a matter of semantics. "Output" capacitors can be said to be performing a coupling function, since they are in series with the linestage input (on a phono only stage).