Sensation Dodd Tube Buffer

AndrewH · « **Reply #240 on:** 16 Jan 2011, 05:22 pm »

The Grant Fidelity 12AU7-T is noticeably better than the stock JJ ECC 803S!

I liken the overall improvement as similar to going from the stock 65w switching power supply to the battery supply - maybe not quite as dramatic an improvement, but similar in character with at least 50% of the magnitude of improvement. The first thing I noticed was the sound seemed more 'relaxed' - this is probably a result of lowering distortion, as there is no loss of resolution, in fact there's probably a gain in resolution. Bass is improved and highs are smoother. The JJ's could be rather penetrating on sibilants and still felt a little fatiguing. Now the sound is eminently listenable for long periods of time. Especially noticeable was the improvement in bass resolution and 'drive'. The best term I can come up with to sum up the improvement is the bass finally sounded 'growly'. The result is more toe-tapping enjoyment.

For about $40 per tube (comes in a two-pack for $84), it's a highly worthwhile investment.

It should be noted - evidently "unity gain" of the buffer means the gain is 1, and is independent of the gain of the tube. I hoped that the 12AU7 having 20% of the gain of a 12AX7 would give me more range in my volume control, but it has the exact same range as before. Maybe I can turn it up a little louder as a result of the lower distortion, but the volume to knob-position relationship is pretty much exactly the same. This only matters by the way because my Omega speakers are pretty sensitive, rated at 93 dB.

And just to speculate on design matters, I'd recommend to Virtue to consider bundling a better tube than the JJ's. The improvement is noticeable enough that it seems a shame to limit the performance of the tube buffer just to save $30 on parts cost (wholesale costs are also probably lower). Let's see, the buffer costs $300 extra. There's probably a 3-4x multiple on parts cost (industry standard). $30 extra for a good tube would translate to a ~$100 higher price. After hearing the improvement, I think the buffer is easily worth $400, especially in combination to the overall price of my M901 at $949. In terms of total amp cost, the extra 8% in (end-user) cost results in maybe 20% better sound. Also, people who spring for the tube buffer in a Virtue amp are probably aiming to get the "best" sound from their Virtue amp, so why not make it easy for them? I probably spent 10-20 hours reading this thread and researching tube types; that much of my time is worth much more than $100. So it'd be great value all around!

Last note. Now that I know the 12AU7 doesn't change the gain, but Dodd provides some guidance that the 12AT7 provides the highest input impedence, I wonder how that sounds. Also, which tube provides the lowest distortion/best sound quality? Oh well, it's hard to imagine the sound improving much from here. Famous last words.

Last last note - forgot to mention - the static sound when changing volume is gone too! For that reason alone probably worth not using the JJs!

wsturner · « **Reply #241 on:** 16 Jan 2011, 11:34 pm »

I am sitting here listening to some old REM - hearing things I never heard before. I was thinking about the way music affects us. I feel that listening to music has a much more profound impact on our experience than most people realize. Consider the origin of the word music.

I had a dream the other night. In the dream, I heard music. The soundstage was huge, every instrument was clearly discernible, it was beautiful. I never dreamed music like this - before hearing something similar in reality. When you can listen to something, and it changes the way you dream, I would consider that pretty deep. Thanks for the amp Seth and Gary!

virtue · « **Reply #242 on:** 17 Jan 2011, 03:44 am »

Gary did NOT prefer the 12AU7 to the JJ's we chose. The JJ's outclassed tubes costing 5 times the price. Anyway, maybe the 12AU7 he used was not as good as yours. He pays nearly retail for the JJs. You may want to email him directly and suggest he change the tube or offer it as an option. Right now he's nuts about a 6v tube and has considered making the buffers 6v capable (no charge).

se-riously · « **Reply #243 on:** 17 Jan 2011, 05:18 am »

Quote from: virtue on 17 Jan 2011, 03:44 am

Right now he's nuts about a 6v tube and has considered making the buffers 6v capable (no charge).

My FedEx account is standing by to send my M451 back to Gary.

OzarkTom · « **Reply #244 on:** 17 Jan 2011, 06:05 am »

I will stay with my Sylvania GB 5751.

se-riously · « **Reply #245 on:** 17 Jan 2011, 06:33 am »

Quote from: OzarkTom on 17 Jan 2011, 06:05 am

I will stay with my Sylvania GB 5751.

I love mine too. However, extra tube flexibility never hurt.

virtue · « **Reply #246 on:** 18 Jan 2011, 12:19 am »

Reach out to Gary if you want the 6v upgrade. I'm sure he'll be happy to work something out.

TrungT · « **Reply #247 on:** 18 Jan 2011, 01:05 am »

Very nice

brother love · « **Reply #248 on:** 25 Jan 2011, 04:05 pm »

I got a GE 5751 triple mica black plate tube this weekend (Thanks OzarkTom !

).

Vs. the stock JJ tube, GE 5751 bass is better defined, meatier w/ more depth. Overall sweeter sound. I rocked out w/ it this weekend, but listened to Yo Yo Ma- The Dvorak Album last night. Man, that cello never sounded better on my system.

The GE 5751 w/ 75% or so of the 12AX7 gain is a bit noiser w/ the "leave rustling" volume adjustment. But then who cares when you are lost in the music? I don't ...

I have a Sylvania GB 5751 gray plate on the way that I'm anxious to audition as well. I'll post impressions hopefully this weekend.

srb · « **Reply #249 on:** 25 Jan 2011, 07:29 pm »

Quote from: zmanastronomy on 25 Jan 2011, 06:43 pm

Also, One 24v battery instead of two 12v batteries are much better for the consumer.

Information on the website says
"Note: with a 12 volt charger this battery can be configured for 12volts @10 AH
12 volt charger special order (Dodd Audio 12V products)"

This would lead me to believe that the battery pack consists of 2 - 12V 5AH batteries, although Gary would be the one to verify this. I don't think it would make much difference, and 12V 5AH replacement cells are probably a little easier to source anyway.

Steve

TrungT · « **Reply #250 on:** 25 Jan 2011, 08:50 pm »

Not the best picture, but ...

virtue · « **Reply #251 on:** 27 Jan 2011, 09:39 am »

Gary's a stud! Safety first! If you don't have a box for your battery kit, order one!

brother love · « **Reply #252 on:** 27 Jan 2011, 01:56 pm »

Quote from: virtue on 18 Jan 2011, 12:19 am

Reach out to Gary if you want the 6v upgrade. I'm sure he'll be happy to work something out.

Fyi for those interested...

I've sent a couple e-mails to Gary on the Dodd Audio website the past 2 weeks re: the 6v upgrade, but no word back yet.

If I or anyone else finds something out, we should post it here for the benefit of the Virtue Audio family.

brother love · « **Reply #253 on:** 30 Jan 2011, 11:41 am »

Quote from: brother love on 25 Jan 2011, 04:05 pm

I got a GE 5751 triple mica black plate tube this weekend (Thanks OzarkTom ! ).

Vs. the stock JJ tube, GE 5751 bass is better defined, meatier w/ more depth. Overall sweeter sound. I rocked out w/ it this weekend, but listened to Yo Yo Ma- The Dvorak Album last night. Man, that cello never sounded better on my system.

The GE 5751 w/ 75% or so of the 12AX7 gain is a bit noiser w/ the "leave rustling" volume adjustment. But then who cares when you are lost in the music? I don't ...

I have a Sylvania GB 5751 gray plate on the way that I'm anxious to audition as well. I'll post impressions hopefully this weekend.

The Sylvania GB 5751 3 mica gray plate arrived Friday, & I have been listening a lot. It has an open, deep, silky smooth sound that is mesmerizing. Downright sexy.

I compared it to the GE 5751 triple mica black plate & the Sylvania made it sound rather flat with less depth. The GE is really good esp. for the money, but it was bested by a superior tube.

Thanks to all who recommended the Sylvania GB 5751 in the Sensation Dodd Tube Buffer. It is a synergy that makes incredible music together.

TheMonkey · « **Reply #254 on:** 30 Jan 2011, 02:22 pm »

Well, I got a Sensation M901 with the Dodd tube-buffer and the battery-pack (2 x 7,2Ah Panasonic). I changed the caps before X-mas into Mundorf M-cap Supreme Silver-Oil (3,3 uF and 0,01 uF for bypassing) after loads of cap-research and struggle to make them fit in it sounded even more great...

Since the battery power makes the background almost "black" I find it a little bit annoying with the noise-floor of some tubes and even during the warm-up (about 1-2 hours depending on the tube) so I leave the Sensation more and more on standby since someone here said it was totally fine. I'm not sure about the life-length of the tubes in this case? Seems to be different views on that subject...

For the moment I like the sound of the "new" Create Audio 12AX7 best but Sylvania GB 5751 Triple Mica (grey plates and gold pins) NOS is not far from it but my impression is that the noise-floor is higher... I also got a quite "used" Sylvania GB 5751 (without gold pins) but the noise-floor is way to high, maybe since it got so-so results with the TV7 tube tester... Tubes are probably even more subjective than sound since you can see them and you will develop with them during the burning-in and even every single warm-up! A-B comparison is not possible so it's really hard to say that something is "really" better than something else. I don't know how you did it OzarkTom but I'm impressed! Since it can be a little bit tricky with NOS tubes (if you got bad luck you can get really noisy ones...) I would give Create Audio a chance, they were good to talk with (not the tubes...

) and no problem with the shipping at all and the tube sounds great!

Next upgrade will be the Virtue DAC when it comes out!

My Beresford Caiman DAC does the job great but it can always get better!

For you guys who haven't upgraded anything yet I believe the battery-pack is the best way to start. No big deal economically and you'll hear the difference, good or bad, your choice!

OzarkTom · « **Reply #255 on:** 31 Jan 2011, 04:09 am »

Same here on the NOS Sylvania GB, it was the noisiest of all the tubes I tried. I almost returned it to the seller I bought it from. But after about 60 hours, the tube settled in and I now get no noise at all at anytime.

I am still trying to break-in my Raytheon 5751, it is definitely warmer sounding in all frequencies, but still not the detail or focus of the Sylvania. I have read that some likes the Raytheon better, so I will keep trying. That Sylvania is sounding so good, the Raytheon has a long way to go to catch up.

tabrink · « **Reply #256 on:** 31 Jan 2011, 04:56 am »

The Grant Fidelity 12AU7-T is the blackest tube I have used with my 901.
Utterly quiet!
Still enjoy the Sylvania Gold but increasingly find myself reaching for this tube.

wsturner · « **Reply #257 on:** 31 Jan 2011, 05:35 am »

Monkey,

+1 for the Create Audio 12AX7. Since rolling this into my M451, I have stopped looking for other tubes.

I would also consider batteries, and caps, important upgrades. And the Dodd tube buffer, with a great tube, really makes magic happen.

jtsnead · « **Reply #258 on:** 1 Feb 2011, 05:26 am »

if anybody is interested I have a Sylvania GB 5751 for sale in the trading post

Jason T · « **Reply #259 on:** 8 Feb 2011, 03:03 am »

I finally decided to look into some of the tubes you guys are bragging about and quickly realized I'm to damn broke for this hobby LOL

I'm seriously considering the Create Audio 12AX7 I would like a silent tube and something thats warm... very warm