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6sn7/300b

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Posted on March 14, 2013 at 18:23:01
njjohn
Audiophile

Posts: 2114
Location: new jersey
Joined: August 30, 2002
 The 6sn7/300b is possibly the most set sounding amplifier, especially in a pair of monos. By 'set sounding' I am referring to a certain type of openness, almost starkness, frankness, ease, that sets excel at more than other types of amps. I am just not really describing the characteristic well. This set openness, in itself, is one of the nicest things in audio sound. I guess I am also talking about ac on the tubes too.

And how nice and special is audio sound in the scheme of things? Pretty fantastic really, don't you think?

I think we really have to continue thanking all of the audio engineers, the tube and sound engineers of the first half of the 20th century.

 

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RE: 6sn7/300b, posted on March 14, 2013 at 21:15:27
jnr
Reviewer

Posts: 2164
Location: San Francisco Bay Area
Joined: April 5, 2000
 I love the sound of that tube combo, but my favorite is the 300B/ 6L6GC combo used in the direct coupled Wavac EC300B. It is really a spooky real sound.
theaudiobeatnik.com

 

RE: 6sn7/300b, posted on March 14, 2013 at 22:55:30
Frihed89
Audiophile

Posts: 15703
Location: Copenhagen
Joined: March 21, 2005
 I also find the SRPP 6SN7 - 300B type SET amp hard to beat for the money. But you need to spend a lot of money on OPTs, chokes to ring the most out of them. And on tubes....that either don't exist (WE300b) or are very hard to find (strong WWII 6SN7GT).

 

RE: 6sn7/300b, posted on March 15, 2013 at 02:43:28
njjohn
Audiophile

Posts: 2114
Location: new jersey
Joined: August 30, 2002
 That could be more elemental since isn't the 6l6 half of a 6sn7?

The single driver and the single output tube.

I think I have one around but in a stereo, not monos.

The additional freedom and ease of seperate power supplies for each channel.

 

RE: 6sn7/300b, posted on March 15, 2013 at 02:56:52
njjohn
Audiophile

Posts: 2114
Location: new jersey
Joined: August 30, 2002
 Are you referring to an original WE300b? If there is/was one I never heard it.

I was never a fan of the WE300bs that I have heard. Not open enough compared to TJ's and others.

The SRPP is a 6sn7 circuit that came after the original fi primer. The fi primer is primordial city.

 

RE: 6sn7/300b, posted on March 15, 2013 at 03:07:47
njjohn
Audiophile

Posts: 2114
Location: new jersey
Joined: August 30, 2002
 What's sad about all of this is that this audio sound is one of mankind's greatest things and it is likely to be lost to future generations. In fact, most of it is kind of lost now.

I'm listening to "Kind of Blue". I guess it will always be about my favorite. It is preserved. Rembrants are preserved.

But the primordial treasure of audio sound, 50's and earlier, a golden era, is unlikely to be available.

 

changes in sound in 20-30 minutes, posted on March 15, 2013 at 03:20:41
njjohn
Audiophile

Posts: 2114
Location: new jersey
Joined: August 30, 2002
 A good amp will turn into a 'beast' in 20-30 minutes. By this I mean it will open up and be able to take over the senses. The listener becomes more passive. It's hard to explain: you would have to know ahead of time what I am talking about. I guess everything else has to be right too: the sound has to fill the room.

I've always assumed it was something related to the electronics. That is how it sounds but I could never rule out that it is in interaction with the listener too.

Sorry for the silly post. Just enjoying the audio.

 

4P1L into 4P1L PSE, posted on March 15, 2013 at 03:46:13
andy evans
Audiophile

Posts: 4382
Joined: October 20, 2000
 As good as 6SN7 into 300b is, I'm getting better sound from 4P1L (triode) as a driver, interstage coupled to PSE 4P1L output stage. The power output is slightly more than a 2a3 but not as much as a 300b. The 4P1L is a great tube in triode - better than 6SN7, though gain is about half. But as an output tube 4P1L has three times the gain of the 300b. One reason this combo sounds good is that I use ALL the tubes in filament bias. No caps anywhere, no cathode bypasses.

I used 300b SETs for quite a while, but when I found better I couldn't see the need any more, and it sure saved me a lot of money too!

 

RE: 6sn7/300b, posted on March 15, 2013 at 05:04:16
Frihed89
Audiophile

Posts: 15703
Location: Copenhagen
Joined: March 21, 2005
 No, I am not sure what the "original" actually is. I was referring to several DIY amps I have heard or seen (schematics) with that typology + tube. Granted, power supplies differ and probably make a signifigant difference. There are also number of amps that use a 6SL7 instead.

I'm talking cap-coupled, not dc- or transfomer- coupled. I get the impression that while dc-coupling looks simple, I don't think it's as easy to get good sound as the 6Sn7 SRPP.

 

RE: 6sn7/300b, posted on March 15, 2013 at 07:57:31
Palustris
Audiophile

Posts: 2408
Location: Cape Cod
Joined: September 12, 2008
 "The SRPP is a 6sn7 circuit that came after the original fi primer. The fi primer is primordial city."

Valley and Wallman proposed the SRPP and provided mathematical analysis in their landmark 1948 book 'Vacuum Tube Amplifiers.' JC Morrison put together his primer as a collection of Japanese and American hobbyist schematics about 1990. It is a great resource and you can learn plenty from it. I have both 'Vacuum Tube Amplifiers' and Morrison's primer.

 

RE: 6sn7/300b, posted on March 15, 2013 at 08:19:17
Palustris
Audiophile

Posts: 2408
Location: Cape Cod
Joined: September 12, 2008
 "That could be more elemental since isn't the 6l6 half of a 6sn7?"

The 6J5 and 6C5 are half of a 6SN7. Before that was the 76/6P5, 6L5, 37, and 27. These are all available with cylindrical plates and the 27 and 37 with mesh plates. Until you have heard all these tubes you can't make a qualitative judgement re: the 6SN7. Personally, I have tried all these tubes and now use the 6N23P to drive my 300B although I have been very satisfied with the 7119/5687 as a driver. Here's a sample circuit that uses both the 76/6P5/37/27 as a voltage amp and a 5687/7119 as a direct coupled choke loaded driver. I would put it up against a 6SN7 cap coupled driver any day. Note also that the Wavac uses the 6L6 as a triode connected driver through an interstage transformer. That's a very different beast and another way of eliminating the coupling cap from the driver tube. You will never get the most transparent and harmonically rich sound cap coupling the driver to the 300B.



 

RE:300b, posted on March 15, 2013 at 14:50:50
unclestu
Dealer

Posts: 5851
Joined: April 13, 2010
 According to Magers who wrote a book on WE tubes the 300B was manufactured till 1987. The "new" 300B made by AT&T sound and seem to be made to the same specs as the original.

I own a couple of NOS 300B's c 1952, and compared them. to the new manufacture: couldn't tell the difference at all. This was in a wright Audio AU-30, IIRC

Had an aquaintance with a Cary Audio integrated. Ran his new 300B's for 7 years without ever turning off the amp. Tubes still tested as new, surpassing minimums on my TV-7.

another acquaintance changed the TJ mesh plates in his Wyetech for new ATT 300B's: got better bass ( noticeably), better detail, superior soundstaging. Even though rated at lower power, it sounded way more powerful.

But of course YMMV

 

RE:300b, posted on March 15, 2013 at 16:09:52
Frihed89
Audiophile

Posts: 15703
Location: Copenhagen
Joined: March 21, 2005
 I have a pair of the new WEs. Can't disagree. Others are too dry or too rich. But there are no more WE tubes, so the world is less well off for it!

 

RE: 6sn7/2A3, posted on March 15, 2013 at 16:20:55
dvb
Audiophile

Posts: 2444
Location: Vancouver
Joined: August 18, 2000
 Would get my vote for the most "SET" sounding - but I have absolutely no doubt that "YMMV", and that it is very much a matter of taste.

 

RE:300b, posted on March 15, 2013 at 17:57:46
kyle
Audiophile

Posts: 1839
Location: London Ontario
Joined: September 29, 1999
 I find all of the mesh plate tubes I've heard to be a bit lighter sounding than their solid plate relatives. They make outstanding mid/highs amps though. Maybe even for those who think bi-amping requires matched amps.

 

You're gonna, posted on March 15, 2013 at 19:51:02
unclestu
Dealer

Posts: 5851
Joined: April 13, 2010
 freak when you read this, but I met a guy who has a CASE of NOS we 300B's (50). Apparently they came with his WE 91 amps that he inherited from his uncle......

 

Hmm, posted on March 15, 2013 at 22:38:04
Caucasian Blackplate
Industry Professional

Posts: 8313
Location: Seattle
Joined: June 18, 2004
 6SN7 SRPP is going to have a tough time driving a 300B...

 

Roughly 500 years worth of tubes! nt, posted on March 16, 2013 at 01:37:40
Frihed89
Audiophile

Posts: 15703
Location: Copenhagen
Joined: March 21, 2005
 nt

 

Yeah....., posted on March 16, 2013 at 01:59:11
unclestu
Dealer

Posts: 5851
Joined: April 13, 2010
 I'm trying hard to have him sell off a few tubes. The tubes in the 91 amp have never been changed and still test as new !

I just want to see those amps, too, being almost so mythical.....He says they are still in working condition and was used regularly.....

I used to get so jealous, as he also has every tube model that Marantz ever made, including a double set of spare output transformers for his Model 9's......


Some guys.....I feel like a bottom feeder around him


stu

 

RE: Yeah....., posted on March 16, 2013 at 10:06:31
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
 Last time I visited Alan Sides in LA, long time ago, he had about 19 Marantz Model 9s in his studio, Oceanway.

I have known Alan, bought amps from him since 1973 or so, 40 years.

Jeff Medwin

 

Not enough gain?, posted on March 16, 2013 at 11:53:07
Tre'
Industry Professional

Posts: 17302
Location: So. Cal.
Joined: February 9, 2002
 .
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: 6sn7/300b, posted on March 16, 2013 at 12:19:33
danlaudionut
Audiophile

Posts: 5480
Location: Schenectady
Joined: June 6, 2002
 Palustris

I just have to jump in here since
you mentioned both my favorite tubes.
I have a SE 6P5/6L6GC amp that's awesome.
Rich harmonics and excellant staging.
It just pulls you into the music 8^D

DanL



 

RE: Not enough gain?, posted on March 16, 2013 at 16:05:36
Paul Joppa
Industry Professional

Posts: 7296
Location: Seattle, WA
Joined: April 23, 2001
 I've had a mu-follower 6SN7 driving a 300B, and with a preamp that has some gain and headroom, it sounded quite good. This is not of course a real SRPP which has half the gain. I had set the circuit up so that a 6SL7 could be substituted, but the 6SN7 was preferred by almost everyone (including myself). It sounded much better taking drive from the lower tube plate rather than the upper tube cathode, incidentally.

In the end, I went to a 6J5 - half a 6SN7 - with a current source plate load; it just sounded better to me. I wound up with a slight preference for a 2A3 over a 300B, both operating at 18 watts plate dissipation. I had a bunch of cheap Chinese biplate 2A3s so I could afford to replace them every 750 hours or so!

But I think there may be some confusion - the most popular 6SN7 driver topology is a two-stage direct coupled driver arrangement (three-stage amp), which has a very high gain. I have not experimented with these three-stage amp topologies myself so I won't speculate on the sonics. Many people like them a lot.

 

RE: 4P1L into 4P1L PSE, posted on March 17, 2013 at 01:23:15
jusbe
Audiophile

Posts: 5950
Location: North Island
Joined: April 4, 2000
 Does anyone use this tube commercially?

Have any photos?

Big J

"... only a very few individuals understand as yet that personal salvation is a contradiction in terms."


 

RE: 4P1L into 4P1L PSE, posted on March 17, 2013 at 02:53:51
andy evans
Audiophile

Posts: 4382
Joined: October 20, 2000
 4P1L is a copy of a German Wermacht directly heated tube which is now unobtanium. It was made in reasonably good quantities in Russia and is currently available from Russian and E.European sources. As far as I know there are no known commercial amps or line stages using it. It is usually used in triode. It has a loctal base, and these are available cheaply on ebay in a decent Chinese version. Plenty of information on building with it on DIY Audio in the thread "one more 4P1L SE".

In triode you can think of it as something like a 45 - just under 2K plate resistance and 8 watts plate dissipation. It has a centre point in the filaments. I use the filament sections in parallel at about 1.9v, and join pins 2+3+4 on the base to form the plate. It has a useful gain of around 10. It's microphonic as an input tube but usually OK for driver and output. See below:

http://www.bartola.co.uk/valves/tag/4p1l-pre-amplifier/

 

Thanks Andy. -t, posted on March 17, 2013 at 03:18:56
jusbe
Audiophile

Posts: 5950
Location: North Island
Joined: April 4, 2000
Big J

"... only a very few individuals understand as yet that personal salvation is a contradiction in terms."


 

RE: Not enough gain?, posted on March 18, 2013 at 21:51:03
Naz
Audiophile

Posts: 2184
Location: Sydney
Joined: September 2, 2005
 >>It sounded much better taking drive from the lower tube plate rather than the upper tube cathode, incidentally.<<

For the record the circuit is no longer a mu follower, it becomes a less than ideal tube CCS but I can't agree more Paul. Hard to explain but it's somehow more musical and 3D.

Drive taken from the top tube's cathode might initially sound more impressive but is more irritating to my ears.

Naz

 

RE: changes in sound in 20-30 minutes, posted on March 18, 2013 at 22:14:25
Naz
Audiophile

Posts: 2184
Location: Sydney
Joined: September 2, 2005
 Never a silly post when the sheer pleasure of what you are hearing moves to write it!

Ever tried a Ruskie metal based 1578? This is the best variety of all the 6SN7's I've heard. I used to pick up matched pairs for $25 but it seems that others have found how good these sound.

Cheers,
Naz

 

RE: 6sn7/300b, posted on March 19, 2013 at 11:43:56
dividebytube
Audiophile

Posts: 73
Location: Midwest
Joined: February 5, 2013
 I like to use pentodes for driving my SE toobs - 6C6 worked great for a SE 2A3 amp, and the SV84/EL84 is a monster for driving the 300B. Both give a quick, delicate sound with some the most transparent treble I've heard.

 

RE: 6sn7/300b, posted on March 20, 2013 at 13:28:24
Palustris
Audiophile

Posts: 2408
Location: Cape Cod
Joined: September 12, 2008
 "I like to use pentodes for driving my SE toobs - 6C6 worked great for a SE 2A3 amp, and the SV84/EL84 is a monster for driving the 300B. Both give a quick, delicate sound with some the most transparent treble I've heard."

I collected a bunch of 6C6 tubes with the intention of trying this. Maybe this spring...

If you like the EL84 driving a 300B you could also try the E80L/6227 if you can find a pair cheap.

 

RE: Not enough gain?, posted on March 21, 2013 at 12:42:19
TubeDriver
Audiophile

Posts: 794
Location: East Coast
Joined: February 16, 2007
 I have had a couple 3 stage 6sn7/300B type amps with the circuit you describe. I think they sound pretty good but as you mentioned the gain is way to high (especially with my 100db horns).

I have plenty of gain with 2 stage 1/2 a 6sn7/6bl7/6dn7 to 300B even using a "passive" autoformer preamp. May not be technically the "correct" thing to do but it sounds great in my system.


Most amps have way to much gain for horns.

 

RE: 6sn7/300b, posted on March 21, 2013 at 15:21:07
njjohn
Audiophile

Posts: 2114
Location: new jersey
Joined: August 30, 2002
 Yea, I have to agree. The pentode I have that drives a 45, I had mentioned in another thread, is really a surprisingly great amp.

 

RE: Not enough gain?, posted on March 22, 2013 at 09:22:07
Tre'
Industry Professional

Posts: 17302
Location: So. Cal.
Joined: February 9, 2002
 "Most amps have way to much gain for horns."

Most amps have way to much gain, period.

I use a passive AVC preamp, 2 stage amp with 1/2 5687 driving 6b4g SET into 96db speakers. Mids and highs only, crossed at 190Hz.

I have plenty of gain and plenty of power for my needs.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: Not enough gain?, posted on April 8, 2013 at 13:39:29
Retsel
Audiophile

Posts: 1239
Joined: April 17, 2000
 Hey Paul, have you also tried the 6N1P tube in that amp to see how it compares to a 6SL7 and an 6SN7? I would be curious to find out how the 6N1P fares....

 

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