stealth 60

londonbarn · « **on:** 12 Nov 2006, 07:43 am »

hi guys , i never see any comments about the stealth 60 and maybe how it compares to a dynaco st70 even with the special red board.... any owners out there??? thank you

quinnling · « **Reply #1 on:** 2 Feb 2007, 11:56 pm »

I have check out the schematic of the stealth 60 and the red board. From my personal experience, the pentode gain stage has been vastly underrated. It was really nice to see a 6SJ7 and 6SL7 being used. There is something special in the sound with a pentode, the midrange seems very "fleshed" out. Anyways, I am not challenging the choice of the 6SL7, but can a 6SN7 being used, and/or a current source phase splitter. My guess, is a current source is not easily be directly coupled, and the 6SN7 may not have enough gain.

I just want to know the decision made by the experts, and hopefully I can learn something.

Regards,
Quinnling,

P.S. Toronto is a great city !!! I used to visit it once a year.

WEEZ · « **Reply #2 on:** 3 Feb 2007, 12:20 am »

It seems that there is conflicting info on the website regarding the Stealth 60.....

The blurb on the main page indicates it's a 60C..with tube rectification. When you click for more info, it doesn't say anything about that. Also, there is info somewhere that the input z is 110k, and somewhere else it says 430k.

Anyway, it looks like a combination of a Dyna Stereo 70 and an Eico. Which is not a bad thing.

If anyone has heard one, or has information on one.....let's have it!

WEEZ

SteveRB · « **Reply #3 on:** 3 Feb 2007, 05:14 pm »

i have the new stealth 60c on order... when it arrives i will give you my impressions.

regarding the the changes-- i spoke to lloyd, who said the new tube recticifation is necessry because he is upgrading the transformer to eliminate the need for two start up switches. i belive this is the difference between the 60b and the new 60c. (it looks to me that i am the first to order the new 'c' version...?) that being said, he is a busy guy and i don't think he has the time to update the website with the most current info.

WEEZ · « **Reply #4 on:** 3 Feb 2007, 05:53 pm »

..looking forward to your comments, thanks.

quinnling · « **Reply #5 on:** 15 Feb 2007, 02:42 am »

Will there ever be mono boards avaible for the DIY ? Used for Dynaco 3 or any homebrew application? I can alway build it from the publish schematics, but I feel it is not the right thing to do.

Quinnling

jeffdavison · « **Reply #6 on:** 16 Feb 2007, 07:08 am »

The SR70 is a wonderful sounding product and it is waaaaay under priced.
I put mine in a scratch built ST70 chassis and basically separated it into dual mono. The layout lends itself to this quite readily.
Lloyd posted a pic of my amp last month on his website. It is still up last I looked.

btw.. I asked Lloyd about the input impedance and it is indeed 430K

JD

Berndt · « **Reply #7 on:** 17 Feb 2007, 12:47 am »

great picture, those are butch monoblocks.
Can you tell us more about the design goals and how it sounds?
What speakers are you driving?

jeffdavison · « **Reply #8 on:** 18 Feb 2007, 06:18 am »

goals...as much triode in an ST70 form factor package. I like the size of the amp as well as the nostalgic look.

The amp sports 2 Toroid power transformers from Toroid Corp. Each has about the same specs as the Dynaco MK3. Output transformers are Edcor 60 watters (if I only had another 1/4" more they'd have been the 100 watt puppies but alas, the 5AR4's needed the same space).
I modified Lloyd's SR70 ever so slightly, splitting up the grid leak resistors so I can have individual bias pots for each tube. Just in Case I ever wanted to to Ultraliniear I put a single 4PST switch in the amp. An all in one Corcomm power entry module with switch / filter / fuse is out back... really cleans things up along with 2 sets of 2 pairs of Cardas speaker connectors.
Because Toroids have faster inrush of ac current, a paralled set of CL90 thermistors stops the slo blow fuse from going thermal.

Speakers.... again going with the nostalgic theme but with modern guts... The amp is paired with a set of original Large Advents BUT....
the drivers have been gutted. I am only using the cabinet and grill covers. The driver arrangement is a pair of Accuton 7" C296 woofers with a Raven R2 ribbon driver in MTM Appolito fashion.

I built this system for vinyl only. Front end is a heavily modified Thorens TD160..built up a sub chassis with foam sandwich carbon fiber and a redesigned bearing assembly using a carbide ball bearing instead of a flat metal thrust pad. Arm is a likewise very "tweaked" SME 3009 series 2 improved that I have taken may liberties with.

Preamp in very minimal. I had an old original Moscode Super "IT". It was recently updated by George Kaye and the new New York Audio Labs.

Now if you ask me about tube rolling.... ;^)

Doing my own sub woofer with another tweaked "old" piece of audio history...A Dahlquist crossover has been hot rodded with updated jfets, foil resistors and "boutique" caps. Scratch building the boxes using Scan Speak 9" revelators with a passive radiator (only needs 1 cu.ft to get F3 at 23 hz) Will be all black and "hidden" as the speaker stands.

Ultimate design goal was for a complete system that looked out of the 70's and 80's, but can compete with current state of the art equipment. So far, so good.

JD

londonbarn · « **Reply #9 on:** 19 Feb 2007, 08:32 pm »

Boy, I should say!

rockadanny · « **Reply #10 on:** 13 Mar 2007, 12:02 pm »

The suspense is KILLING me! Stealth 60 review? experiences? Anybody? I see one in the build queue. I assume its astro's?

SteveRB · « **Reply #11 on:** 17 Mar 2007, 09:08 pm »

i got the ultra4 pre last week, but dr lloyd had to complete another project before the stealth 60... so i am still waiting. the preamp is a huge success right out of the box... i will post more indepth comments after in a few weeks...

WEEZ · « **Reply #12 on:** 13 Apr 2007, 09:39 pm »

Any updates on the 60c??

WEEZ

Berndt · « **Reply #13 on:** 18 Apr 2007, 11:49 pm »

what tubes are you running in the U4?

topround · « **Reply #14 on:** 19 Apr 2007, 12:49 am »

I am using Slyvania GTA 6sn7's from the 50's and they are terrific!!!!!!!!!!!!!!!!!
I borrowed Dr.LLoyds 12sx7's for my rave and they sounded good until I put my Sylvania's in, it became a totally different preamp! It moved a few steps better. Same great tone but so much more drive and prat, much less distortion and SO MUCH MORE AIR. It was unbelievable.
This pre responds to tube rolling!
BTW I get my tubes from Vintage Tube Services, Andy is the BEST!!!

rajacat · « **Reply #15 on:** 22 Apr 2007, 08:53 pm »

Quote from: topround on 19 Apr 2007, 12:49 am

I am using Slyvania GTA 6sn7's from the 50's and they are terrific!!!!!!!!!!!!!!!!!
I borrowed Dr.LLoyds 12sx7's for my rave and they sounded good until I put my Sylvania's in, it became a totally different preamp! It moved a few steps better. Same great tone but so much more drive and prat, much less distortion and SO MUCH MORE AIR. It was unbelievable.
This pre responds to tube rolling!
BTW I get my tubes from Vintage Tube Services, Andy is the BEST!!!

Hmmm...Thanks for the tip and incentive. The 6SN7's have interested me but I just haven't gotten around to trying a pair.Today I found out that a neighbor of mine has a pair of RCA 6SN7'S 5692 redbase that I will try and maybe buy. Have you tried the RCA's?

Raj

Berndt · « **Reply #16 on:** 28 Apr 2007, 04:36 pm »

the red base rca's usually command 200$ a set...FWIW.

I'll have to try the sylvanias again.

WEEZ · « **Reply #17 on:** 30 Apr 2007, 10:00 pm »

60C update request bump

WEEZ · « **Reply #18 on:** 6 May 2007, 11:39 pm »

bump-de-bump

rajacat · « **Reply #19 on:** 7 May 2007, 01:20 am »

Quote from: topround on 19 Apr 2007, 12:49 am

I am using Slyvania GTA 6sn7's from the 50's and they are terrific!!!!!!!!!!!!!!!!!
I borrowed Dr.LLoyds 12sx7's for my rave and they sounded good until I put my Sylvania's in, it became a totally different preamp! It moved a few steps better. Same great tone but so much more drive and prat, much less distortion and SO MUCH MORE AIR. It was unbelievable.
This pre responds to tube rolling!
BTW I get my tubes from Vintage Tube Services, Andy is the BEST!!!

Unfortunately my neighbor wasn't able to locate the RCA 6sn7 5692 red bases

but he did come up with some Sylvania 1961 JAN 6sn7 brown bases and my reaction is similar to yours. more detail, drive and transparency/air.

I'm realizing that there was some superfluous haze clouding the soundstage that I hadn't known was there until hearing the 6ns7's for the first time. I keep telling myself to make sure that I flip the 6/12v switch when I roll the tubes. My other tubes are the RCA 12sx7's and assorted 12sn7's.

I hope that my friend can find the RCA red bases so that I can compare and see it they live up to their price tag.

Raj

p.s. He also has some International Servicemater 6SL7's. Anybody know if you can use these in the Mapletree?