AudioNervosa

Systemic Development => Amplification and Preamplification => Topic started by: Bunky on May 15, 2011, 09:00:11 AM

Title: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: Bunky on May 15, 2011, 09:00:11 AM
i am considering trying one of these with the 93.5 db Silverline Sonata's.Six Moons gave a favorable review of this amp and the reviewer did not have a problem driving a 91 db pair of Devore Fidelity loudspeakers with it.the Bravo 2.3 also had good reviews from Soundstage including a reviewers choice award. i think i can pull off driving the Sonata's with a 18wpc SET amplifier. does anyone here have a opinion about this ? thanks....WCW III
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: richidoo on May 15, 2011, 09:31:03 AM
My guess is that it will be borderline for symphonies, but fine for mildly compressed jazz, or highly compressed rock/pop stuff. 6C33 makes a lot of current so mild impedance dips to 3ohms should be OK if the transformers are good. If it is a cheapo Ebay type amp usually the transformers are the first thing compromised making speaker matching harder.

My 24W sepp 300B amps were loud enough on compressed music for the 90dB Ushers. But on less compressed stuff the dynamic peaks were weak, so I had to crank in more feedback for that. Those amps are not strong enough for Shane's Harbeth 40.1, which is an easy load but low sensitivity.
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: rollo on May 15, 2011, 10:37:07 AM
  My speakers are 94db and using an 18W SET. I see no issues other than what Rich mentioned about the Trannies. Money back before 30 days ? If so give it a go man.


charles
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: djbnh on May 19, 2011, 03:09:14 AM
Bunky, I thought you picked up a Niteshade amp not too long ago. Glad to see the Nervosa is still strong in you, young Skywalker!  :rofl:
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: rollo on May 19, 2011, 08:36:39 AM
Quote from: djbnh on May 19, 2011, 03:09:14 AM
Bunky, I thought you picked up a Niteshade amp not too long ago. Glad to see the Nervosa is still strong in you, young Skywalker!  :rofl:

  Its the SET curse. Oh yes once bitten the SET Vampire appears, oh my !!



charles
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: richidoo on May 19, 2011, 10:30:01 AM
Also Bunky is AN's unofficial tube amp reviewer.  :thumb: 
So many tube amps, so little time!   :thumb:
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: Bunky on May 19, 2011, 04:42:18 PM
Oh yes i am still very smitten with the NS-40 but i do very much like SET amps. Blair Has a 40 wpc + SET amp design on the back burner for me just as soon as i give the word in fact we discussed this amp while the Crimson Red Pearl paintjob was still drying on my brand new NS-40  :rofl:.you would have to spend a considerable amount of money to get a better push pull than the NS-40. Blair is very talented Man. :thumb:
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: rollo on May 20, 2011, 07:21:27 AM
Quote from: Bunky on May 19, 2011, 04:42:18 PM
Oh yes i am still very smitten with the NS-40 but i do very much like SET amps. Blair Has a 40 wpc + SET amp design on the back burner for me just as soon as i give the word in fact we discussed this amp while the Crimson Red Pearl paintjob was still drying on my brand new NS-40  :rofl:.you would have to spend a considerable amount of money to get a better push pull than the NS-40. Blair is very talented Man. :thumb:

40W ????? SET. Got my attention. Parallel SET ? My next SET will be a 300B based Parala ll with either a 6550 or 6SN7 driver. Not sure of the Trannie yet, though. Audio Note, Lundhal, Bartolucci, NOS. An outboard choke regulated power supply. Tube rectified of course.
  "What a day for a day dream. what a day for a day dreaming boy"


charles
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: Bunky on May 31, 2011, 04:14:50 PM
i just sent payment for the Bravo 2.3 maybe i can get it by the weekend  :)
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: richidoo on May 31, 2011, 04:50:00 PM
(http://www.jas-audio.com/member/67473/diy/Bravo2_3.jpg)

Mfg: http://www.jas-audio.com/index_topic.php?did=157961&didpath=/156834/157961
Dist: http://www.natdistribution.com/jas_audio.htm

http://www.soundstage.com/revequip/jasaudio_bravo23.htm
http://www.6moons.com/audioreviews/jas4/bravo.html
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: BobM on May 31, 2011, 06:05:32 PM
Pretty. Do you think it might drive my 83db inefficient Apogees?  :wtf:
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: Bunky on June 03, 2011, 03:34:04 PM
I hooked it up 45 minutes ago and ive been listening to Roger Waters Amused to Death   :drool: it sounds even better than i imagined driving the Sonata III  :thumb:
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: richidoo on June 03, 2011, 03:52:55 PM
That was fast! When you get an itch, you don't mess around! 

Sounds like it's gonna be a late night....
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: Bunky on June 03, 2011, 05:23:13 PM
Hey Rich, the one in the photo that you kindly provided is the earliest version with the wood deck surrounding the tubes. they replaced it with a 3/8" lexan deck over the black paintjob with red lettering marking the tube positions.it was a very scary proposition placing a piece of wood that close to a 6C33-B  :duh as hot as those babies run  :shock:. the bass is excellent as are the mids and the treble has a nice sparkle to it.call it class A SET with testosterone  :rofl:
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: richidoo on June 03, 2011, 06:59:03 PM
Quote from: Bunky on June 03, 2011, 05:23:13 PM
call it class A SET with testosterone  :rofl:

Good synergy!  You found one of those magic combos
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: Bunky on June 11, 2011, 07:35:36 PM
I have replaced the 5Z3P rectifier tubes with some 5U4G Sovtec's that were actually made by Svetlana in St Petersburg.i have NOS Russian Military 6J4P input tubes coming from across the pond and i have a Quad of NOS Winged C 6C33-B Svetlana's on the way from Mother Russia which are very rare and were made in the mid to late 1960's. these 6C33-B's were not only used in the Russian MIG 25 FOXBAT fighter jet. that crazy guy Rommy the Cat has a picture on his website of these tubes mounted inside of a Soviet Cruise Missle  :shock:
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: richidoo on June 11, 2011, 07:58:35 PM
That is cooool!!!
http://www.romythecat.com/GetPost.aspx?PostID=9434

Thanks William

Shane there is some great 6C33 discussion on the page linked above.
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: tmazz on June 11, 2011, 10:18:59 PM
Quote from: Bunky on June 11, 2011, 07:35:36 PM
these 6C33-B's were not only used in the Russian MIG 25 FOXBAT fighter jet. that crazy guy Rommy the Cat has a picture on his website of these tubes mounted inside of a Soviet Cruise Missle  :shock:

Of course, that way the jet and the missile would both still function ofter the magnetic pulses emitted by the bombs in a nuclear war had wiped out all of the semi-conductors.
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: Bunky on June 12, 2011, 06:15:51 AM
Electro magnetic pulse will fry transistors leaving the bulk of western fighter jets ,bombers and missles stranded and Commie tube equipped aircraft would be immune to this and in theory be able to still function to have a second strike capability. did the guys with the stars and bars at the Pentagon know this ? maybe it was just cheaper for thier defense contractor cohorts to build solid state avionics to maximise profits instead of using tubes that are immune to EMP. this is just another of many reasons why TUBES RULE !  :rofl:
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: rollo on June 12, 2011, 06:55:27 AM
Quote from: Bunky on June 12, 2011, 06:15:51 AM
Electro magnetic pulse will fry transistors leaving the bulk of western fighter jets ,bombers and missles stranded and Commie tube equipped aircraft would be immune to this and in theory be able to still function to have a second strike capability. did the guys with the stars and bars at the Pentagon know this ? maybe it was just cheaper for thier defense contractor cohorts to build solid state avionics to maximise profits instead of using tubes that are immune to EMP. this is just another of many reasons why TUBES RULE !  :rofl:

Coluld be, my bet it was the enviormental crowd who regulated out tube now lightbulb manufacturing here.  :duh 


charles


charles
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: tmazz on June 12, 2011, 08:22:32 AM
My comment was rather tongue-in-cheek, but the MiG-25 was designed in the early 1960s when solid state was still in it's infancy and tubes were still the technology of choice for many applications, especially in some of the high power RF and radar circuits used in the MiGs.

As for the design of our own aircraft the changeover to solid sate devices and ultimately IC based circuitry was not driven by cost bit rather the desire for more advanced capabilities in terms of aircraft control, navigation and radar, communications and weapon systems.  None of the advances systems in the current vintages of our military aircraft would be practical (or maybe even possible) using all tube designs because of size, weight and heat issues. I dare say the if the electronics of a current F-15 was built using all tubes you would have trouble fitting it all in a single aircraft hanger, never mind a single aircraft.  :shock:
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: hometheaterdoc on June 13, 2011, 08:42:57 AM
Quote from: richidoo on June 11, 2011, 07:58:35 PM
That is cooool!!!
http://www.romythecat.com/GetPost.aspx?PostID=9434

Shane there is some great 6C33 discussion on the page linked above.

Thanks Rich... I'd already read everything on that website before starting down the path with Sol on the amps...  I'll be very interested to hear what Sol's design is going to sound like whenever it finally gets built... he said he was going to go back to it for the first time in months after I left his place last night.... with the amount of changes made to it during this prototype stage, it hardly resembles the original amp we conceived... although the autobias circuit for it is still seriously cool..... and having every power supply be seriously fully regulated is definitely going to make it sound different than all the other commercial stuff I've been trying out....
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: richidoo on June 13, 2011, 09:02:09 AM
Quote from: hometheaterdoc on June 13, 2011, 08:42:57 AM
with the amount of changes made to it during this prototype stage, it hardly resembles the original amp we conceived... although the autobias circuit for it is still seriously cool..... and having every power supply be seriously fully regulated is definitely going to make it sound different than all the other commercial stuff I've been trying out....

Agreed! I think the whole gang is looking forward to the unveiling. I know he's been working on it in the last few months cuz I cut some new tube holes a few weeks ago and talked to him about new ideas just before that.

It's coming!
(http://www.theforce.net/swtc/Pix/books/tmotpm/sando1.jpg)
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: hometheaterdoc on June 13, 2011, 12:59:05 PM
yeah... we talked through a bunch of stuff last night as we were trying to sort out all the issues with some other 6C33c monoblocks I bought that showed up damaged courtesy of Fedex... 

getting back to the topic of this thread... I'd love to give the amps that Bunky bought a whirl and see what they sound like... I just don't have any speakers that they'd work on...  I need more juice than these provide...
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: Bunky on July 16, 2011, 12:56:09 PM
i misplaced the manual for my JAS Bravo 2.3 and i went to the JAS Audio website to look at the manual and  i noticed that the rectifier for the 2.3 was a 5AR4 ? mine uses a 5Z3P rectifier tube. i looked at the manuals list and noticed a manual for a Bravo 2.3 SE and when i looked at the PDF i noticed that it uses the 5Z3P and is rated @ 18 wpc. the only differences i can tell from the manuals are that the 2.3 is rated @15 wpc and uses the 5AR4 and the 2.3 SE uses the 5Z3P and is rated @ 18wpc. so my amp is in fact a Bravo 2.3 SE  :thumb:    8)
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: richidoo on July 16, 2011, 01:18:56 PM
Instant upgrade!   :D   Does it sound better now?
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: Bunky on July 16, 2011, 02:39:52 PM
i feel better does that count ?  :rofl: it is dead quiet at full volume thanks to the dual chokes in the right and left channels. it has a very stout power supply for a CHI-FI product and rolling the rectifier tubes makes a big difference. i am currently running the EH 5U4GB which is a copy on a vintage RCA Blackplate. i have some other NOS rectifiers on order. this little 54 lb amplifier sounds even better than it looks   :drool:
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: richidoo on July 16, 2011, 02:46:59 PM
chi-fi - funny!
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: rollo on July 18, 2011, 07:53:50 AM
Quote from: BobM on May 31, 2011, 06:05:32 PM
Pretty. Do you think it might drive my 83db inefficient Apogees?  :wtf:

  No but I bet the Bryston SST2 series amps would blow you away. Still cannot get over how the all Bryston system sounded. Especially with the Lenehan ML-1 Sing. speakers. Even the Carver Amazing speakers sounded the best they ever had.

charles
SMA [ dealer for Lenehan]
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: Bunky on August 08, 2011, 07:13:19 PM
OK i rolled in a pair of  US made 1961 GE 5U4GB and i liked them better than the various Chinese and Russian varients i have experimented with.today i rolled in a pair of highly desireable circa 1944 RCA blackplate Coke Bottle 5U4G and i am very happy with these rectifier tubes in this amplifier  :drool:.i bought these on Ebay from greengirl for $100.00 for the matched pair.these are somewhat hard to find so i will try to find some spares to stash away  :D
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: richidoo on August 08, 2011, 07:22:45 PM
Rectifiers can make a big difference. Sounds like this amp is a keeper?
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: Bunky on August 10, 2011, 02:22:33 PM
this amp has great synergy with my speakers and the rest of my rig so logic would dictate that it is most definately a Keeper  ;)
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: Dallas21 on April 15, 2015, 08:08:07 PM
I would like to mention as far as rectifiers go the 5ar4 is the best
Most rugged rectifier choice why ? for  one it is very rugged long lasting ,also
And this is the most important ,it has a irdirect heater which slowly
Brings up the current for roughly 10 seconds which extends the life of the tube snd  other rectifier  tubes several donot which creates an on rush which taxes the supply capacitors. N.O.S Mullard and Amperex
Are he best ever made and possibly the last one you will buy for your amplifier.
Title: Re: JAS Audio Bravo 2.3 6C33-B Class A SET integrated
Post by: rollo on April 16, 2015, 07:21:48 AM
Quote from: Dallas21 on April 15, 2015, 08:08:07 PM
I would like to mention as far as rectifiers go the 5ar4 is the best
Most rugged rectifier choice why ? for  one it is very rugged long lasting ,also
And this is the most important ,it has a irdirect heater which slowly
Brings up the current for roughly 10 seconds which extends the life of the tube snd  other rectifier  tubes several donot which creates an on rush which taxes the supply capacitors. N.O.S Mullard and Amperex
Are he best ever made and possibly the last one you will buy for your amplifier.

   Hey Dallas21 welcome. Good info thanks.


charles