[SteveFord]

Ever since I heard an Audio Research LS27 I've been on the quest to locate the perfect preamp.  It had to have a wide and deep soundstage, tremendous detail retrieval, even balance from top to bottom AND it had to be in my price range which makes for a very tall order.
I was using a Sonic Frontiers SFL-2 which I just loved but the die was cast after hearing the ARC pre.  As Diamond Dog said, what you've once heard can not be unheard. 
I'll give a real quick rundown of the system in question: VTL 300 DeLuxe monoblocks w/ Winged "C" 6550s, Magnepan 3.7 speakers, Harman Kardon HD7600II CD player used as a transport with an art di/o DAC and a Yaquin tube buffer w/ GE tubes, a Sherwood S3000-III tube tuner, a Well Tempered square motor w/ an Ortofon 2M Black cartridge, a Jolida JD-9 phono stage w/ Sovtek 12AX7-LPS tubes, an APC power conditioner, Kimber 8TC speaker cables, twisted silver interconnects made by the equally twisted owner, the S/PDIF is an inexpensive one from Blue Jeans Cable and the power cords are Supra LoRads that I whipped up.
Enough of the boring crap.
I'd been mildly interested in deHavilland preamps for a long time but it wasn't until I read a few recent threads here on AC that my interest was really rekindled.  One came up at the right price and here it was, at my door.  Happy Day for Funboy here!



I hooked it up and the reviews were right - large and deep soundstage, dead quiet, great detail retrieval, dynamic but a lot of bass which is what I wondered about. 
A gentleman on thecarversite.com was good enough to send me a whole mess of 6SN7 tubes to play around with and what I found to be the best of the lot are the RCAs.  I might be imagining things but of the 5 RCAs that I have, this one is the champion - even tone from top to bottom, great highs if the music calls for it, really great soundstage.



Was I happy?  Yes and no.  I still had more bass than I wanted as my preference is for a very even tonal presentation with nothing that really stands out.  I screwed around with a dozen or so tubes and was getting ready to buy a Shuguan when I decided to write to the lovely and talented Kara Chaffee at deHaviland to see what her recommendations would be.  Who would know better than her?
She said that she would try another tube and let me know and to my surprise, she asked what the input impedence of my VTLs were.
Her idea was to change the coupling caps.
VTL, not surprisingly, did not respond to my email but I found the information in an old Stereopile review and Kara did some calculations and came up with this:
Cap            100hz                 50hz              30hz
.01 uf          -4db                  -8db             -12 db
.02 uf          -1.2db               -4db              -7db
.033 uf        -.7 db                -2 db             -4 db
.047 uf        -.2 db                -1 db             -2 db

and she sent me a care package of caps and some Wonder Solder to give it a whirl.
I only needed to back the bass off like a click or two (if it had tone controls) in order to get it right.
First in were the .033 uf caps and that sounded an awful lot like my old SFL-2 but it was a bit bass-shy.  They came out and the .047s went in and that was much more betterer but still just a bit too much bass.  Picky bastard, aren't I?
Kara suggested running two .022 caps in parallel: one K40 Y9 0.22 Russian and one 0.22 AuriCap and I never argue with a woman as they are usually right.
Pictured are the two 0.22 uf caps alongside the original ones:



It only took a few minutes to install these bad boys




and after 25 minutes or so of warm up, El Perfecto.
I've still got that great soundstage, all the details are there and the bass is blended in perfectly for my room, system and ears.

I can't speak highly enough of Kara Chaffee and her level of customer service and helpfulness.  Talk about going above and beyond the call.  She's aces in my book.
This preamp is exactly what I was looking for. 
If you're in the market for a preamp that brings out the best in your system, my vote would be to spring for one of these.  I don't believe you'll be disappointed one iota.

[medium jim]

Steve:

I have a pair of very nice and strong RCA 6SN7's, one a smoked glass from 1949 and the other from 1957, both have the same construction and are black plates.  My offer still stands if you want to try them out.  PM me if you do.  I saved them because they sounded great.  Right now, I don't have any tube gear that uses  6SN7's. 




Jim

[Emil]

I've had my Dehavilland for  few months now and will be looking into a bit of tube rolling

this may be of interest:

http://www.head-fi.org/t/117677/the-reference-6sn7-thread.

The RCAs seem to be a favorite even by Dick Olsher in his review

http://www.enjoythemusic.com/magazine/equipment/0404/dehavilland.htm

[roscoeiii]

May not be the sound you are looking for, but I found the Psvane 6Sn7s to be superb. Psvanes in general are my fave current production tubes. I would also recommend paying more for the Grade A versions sold by Grant Fidelity

[JP78]

I had an Ultraverve 2 for a while....if I didn't have a need to downsize my system I'd still have it. While it did not excel in any one area, I would say it is the most musical preamplifier I've owned.

[Jon L]

What is that large cap underneath the 0.22 Auricap+0.22 K40Y combo?  Looks like what you are doing is bypassing the large coupling cap (another K40Y?) with 0.22+0.22..

It's always an empiric science with cap mixing and matching, but when it works, it's a beautiful thing.

[SteveFord]

Here's the answer:

The original caps in the UV were  a 1.0 uF K40Y9 and an Auri 1.5 or 1.8uF in parallel.     Your photo looks like you still have the 1.0uF  K40Y9
connected with the small caps.  If you are in the groove sonically--don't change anything!   What I had intended originally  was to remove both the Auri 1.5 and the K40Y9 1.0 .

I misunderstood her but I'm in the groove sonically so I shall take her advice and keep my fat little fingers to myself.

[SteveFord]

So much for keeping my fat little fingers to myself...
I ended up with too little bass so out came the two pair of .22 uF caps and in went a pair of .47 uF AuriCaps which got the balance just right.
The bass is healthy but not overwhelming for me and the mids and highs are right where they should be.
For the 6SN7, I've settled on The Big Three:






Far left with the silver lettering is one from the 60s which was a gift from MediumJim, the orange lettering in the center came with the preamp and I'm told is from the 1970s and the smoked RCA on the right is yet another gift from MediumJim and "is from 1949 and came out of my 1950 Gibson GA30 guitar amp" and was too good for the amp according to him.
All three tubes sound rather similar but I think that the orange lettering comes out on top by a nose.
That concludes my thrilling review on this preamp and thank you to Kara Chaffee for her helpfulness, MediumJim for the great gift of tubes and the people here on AC who pushed me off of the fence and got me to buy this piece.

[Maritan]

I know I'm resurrecting a really old thread, but I wanted to share my first experience with tube rolling.
Here's my system:

Magnepan 1.7
REL T2 sub
VTL ST-150 amp
deHavilland UltraVerve 3 pre
Decware ZP3 phono
Kenwood 770D with Denon DL-110
DIY silver interconnects
Liberty Z500 speaker cables

As I put together my system, I was too impatient to make changes one by one. If, in my research, something was highly regarded,  would make all the changes I could at once. So, there was a time when I put diffusers from Allen (SRL Acoustics - great guy by the way) behind my speakers and rolled a pair of Tele 12AX7s and one Mullard 12AU7 into the ZP3 in one fell swoop. And then, I changed the rectifier on the ZP3 and rolled in Tele 12AT7s into the VTL.

You get the idea, I never really had a good baseline to state how any of those changes affected my system. The only thing I knew was That each change was positive.

You'll note that I didn't make any changes with the UV3. Why? I think deep down I knew that since the UV3 was responsive to rolling, I wanted to leave it alone till I got a decent baseline on my system and then change out the 6SN7 and see what differences I would hear IF I could hear anything at all. You see, I'm not very confident of my hearing skills, and since I live in AZ, the AC and ceiling fan in the listening area are going full blast. Adds to the noise floor etc. etc.

Ok, enough with the background. What was in the UV3 and what did I roll in?

The UV3 came with a Sylvania 6SN7GTA. It had a decent soundstage, but as Steve would attest I was always complaining about the lack of depth. I heard the music and I liked it, but something was lacking.

I rolled in a Sylvania 6SN7W black base that I found for $20! Within the first few seconds of music playing I knew I was hearing a difference. Good or bad? Read on.

The soundstage expanded a little in width. However, the music seemed to come forward a fair bit and go a little deeper. This gave me the additional soundstage depth I have been absolutely craving. Could the depth be a even better? Sure, but I think that's got more to do with the shape of my room than the equipment/ tubes at this point. The imaging was always good, but now there seems to be just a little bit of separation between the instruments/ vocals both laterally and front to back.

There was this clarity. Wow. My girlfriend stopped by for a brief second and commented that the music seemed clearer. Then, there was the speed. The fast drumming was evident, each hit clear and precise. The music was beautifully layered. And the backing vocals were actually separated from the lead and had its own presence. The bass "textures" are there for you to hear clearly now.

At first the bass seemed a little anemic. I was mistaken. The Sylvania GTA was actually a little thick in the bottom end. A little bloom. It was actually even a little muddy if you will. The "W" though was precise. It paired very well with the 1.7 to create some tight, fast bass with the T2 filling in the very bottom admirably. There's a part of this song that is just deep bass notes and I felt along with hearing just like in the concert that I went to California for! I was back at the concert at home!

The highs are... not bright, but very there. Is extended the right word? Air? I don't know. There is no fatigue and believe me I know what listener fatigue is.

The detail retrieval is exquisite. Low level stuff has as much place in the soundscape as the rest of the music.

To summarize - No one portion of the frequency range seems to be more emphasized over the rest. Clean, precise, fast are all great adjectives. I would think of superlatives to describe this tube, but the "W" is insistently transporting me to a Led Zeppelin concert... 

[SteveFord]

This is an old thread - I just saw all of the RCAs I was using.
I'm using a brown base Sylvania VT-231 and I took a look at my second favorite tube (which sounds identical).
It's a brown base Sylvania 6SN7W!  I never even noticed the W on the end until just now.

I've never heard the black base, I wonder if they're any different?

[Maritan]

I know I revived an old thread, but I didn't see another thread discussing tube rolling in the UV3 and I had to share.

Anyway, the true blue Sylvania 6SN7W came only in the metal and black plastic base I believe. However, the Sylvania 6SN7WGT/A/B I think came in the brown base version. Yes, I have spent a few sleep deprived nights researching this.  Not too clear about the Sylvania VT-231. I'll look into that. Either way, point is you're enjoying it.

Today, I've rolled in a black base, orange lettered, bottom D getter, RCA 6SN7. The thicker, somewhat slower bass/ mid-bass is back. The sheer level of bass seems higher, but it needs a diet. Low level retrieval is not as good and gets lost in the mix. Attack seems a little slower, the immediacy of the music is lacking. That sparkling clarity of the W is gone, but the highs are nice. Not as in your face as the W, but very, very nice.

The depth of the soundstage has receded back to what I'm used to. So, average, I'd say.

My least favourite of the three I've tried so far - Syl W, Syl GTA, RCA Orange letter in that order.

I've got a Hytron and a TungSol GTB coming in the next couple weeks. I also have a GE 3 mica, 5 support rod (similar to RCA 5692), and a RCA silver letter to try out.

We shall see how all of that works out.

[SteveFord]

https://www.tubeworld.com/6sn7.htm

http://www.audiotubes.com/6sn7.htm

http://www.head-fi.org/t/209782/the-6sn7-identification-guide

You've probably already seen these links if you've been reading up on them.

One of the ones I've got here says USN-CHS-6SN7WGTA packed 10-57
and the VT-231 box says JAN CGS 6SN7WGT packed 4-59.
Looks and sounds like the same thing to me. 
I should mention that I went back to the .047uf AuriCaps when the 20.7s left and I went back to 3.7s.

You've got plenty of listening impressions to do, sounds like fun.

[djbnh]

Steve, would love to hear an Ultraverve 3, it's not in the current schema/budget. Interesting discussion re: cap changes & effects, not sure how long you let things burn in before critically listening and not sure what difference it would make. Again, interesting reading, thank you.

[Maritan]

Steve - yes, those links have been my go to references. I also do some searches and come up with little snippets here and there that give me some worthwhile info.

[SteveFord]

djbnh,
For burn in and listening it was months at a time - I bought this used and the stock caps were too bass heavy with my room/other gear and then I had the 20.7s for around 6 months so it's back to what works for me with the 3.7s.
Changing cap values makes a much larger difference in the sound that swapping tubes does.
Martin,
Send me your address and I'll send out that VT-231 and you can see if it sounds the same as black base W you have.

[Maritan]

I don't know who Martin is, but I sent you a PM with my address. 

[SteveFord]

Good enough for government work, it'll go out on Saturday.