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Just bought Stax SR-009 (arrggg) but no amp


Jon L

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I just bought the SR-009 which should be here soon.  I have resisted buying them forever because I never really warmed up to its sound signature when I have listened to them, even via Blue Hawaii SE.

 

Yes, I am a lover of single-ended triode (mostly 2A3 and 45) sound.  I don't listen to stuff with lots of bass of dynamic jump, so these days I'm happy listening to my Stax O2 MkI, Senn HE-60 (woody), and HE Audio 'stat via Stax transformer with my 2A3 SET or EL84 sigle-ended pentode speaker amps.  SR-009 should be easier to drive than O2, so that's good, but obviously, a dedicated 'stat amp will be needed at some point.  

 

Blue Hawaii SE, hopefully with some tube, cable rolling may be in the cards.  

Listened to Electra, and 009 sounded pretty good and musical, but obviously bass dynamics were not top-shelf.  Then again, I could live with that.  

Dying to try T2 with SR-009.  Others?

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I was in a similar position a while ago, finally caved and bought the 009s.
There was a crossover period where I had both the 007 mk1s and 009s, I couldn’t afford to keep both.
Both present differently, I liked the 009s vibrance and ethereal qualities, I like the 007s restraint for louder levels and longer listening sessions.
The BHSE sounds absolutely fantastic with the 009s and of course as does the 007s.
For devoted listening the 009s won me over, for background listening for hours a day the 007s may have been a better choice.

 

Oh and congrats!

Edited by johnwmclean
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I one time found myself in a similar situation to you, with a set of 'stat headphones but no amp(s). 

 

Instead of my headphones singing to me, I sang to them. 

When I got an amp they did not forget it and sang to me very lovelyly. 

 

Buy whatever you want/can find quickly as a holdover, and get a BHSE when you can. Not joking. 

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BH/BHSE. Results will depend largely on the source, but listening to well recorded music on the 009 combo is addicting. The 007 will benefit too, a huge lot. As a matter of fact I tend to listen to the 007 even more, things work like John says.

Someone once told me that loading the output of a tube amp--which already has a transformer at the output--with another transformer may result in damaging the amp, or in the best case, diminishing its performance quality. Any knowledgeable around having an opinion?

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Transformer after another transformer is fine if the first one sees the correct load.  Run them unloaded and you get into trouble real quick. 

 

I've always been curious what a Stax/DHT combo would sound like. Might be an interesting joint project.

 

Got any tubes in mind for that?  I've been down this road and I always come to the EML 20B for output duty.  It's the right mix of voltage handling and ease of drive compared to something like the 211/845.  There is a 300B amp in the works too but it is transformer coupled, similar to the Ciuffoli stuff but with a better PSU. 

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Transformer after another transformer is fine if the first one sees the correct load.  Run them unloaded and you get into trouble real quick. 

 

 

Got any tubes in mind for that?  I've been down this road and I always come to the EML 20B for output duty.  It's the right mix of voltage handling and ease of drive compared to something like the 211/845.  There is a 300B amp in the works too but it is transformer coupled, similar to the Ciuffoli stuff but with a better PSU. 

 

That EML20B sure is pretty, but damn at $500+ per single tube, it's a hard pill to swallow.  I did find this EML20B SET on line, and I do love the possibility of a simpler circuitry revolving around the EML20B. 

 

http://www.tubeaudiolab.com/id148.html

 

10042161685_c5a6c777c1_z.jpg
EML20Bamp by drjlo2, on Flickr
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I will do something similar for electrostatics but no way in hell that is better than having a good driver stage. 

 

So for a full DHT amp you'd need some driver, I'd use a IDHT here as there are less issues.  An amp like this would get very expensive... very quickly. 

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Transformer after another transformer is fine if the first one sees the correct load.  Run them unloaded and you get into trouble real quick. 

 

 

Got any tubes in mind for that?  I've been down this road and I always come to the EML 20B for output duty.  It's the right mix of voltage handling and ease of drive compared to something like the 211/845.  There is a 300B amp in the works too but it is transformer coupled, similar to the Ciuffoli stuff but with a better PSU. 

 

I was thinking of sort of a "poor man's" all DHT amp. 4P1l directly coupled to a 6P21S, then interstage coupled to either an 845 or a GM70. 845 then drives a 1:1+1 output transformer.Run the 845 at a relatively low 600V, 60mA plate current, and 100V fixed bias. A few years ago I talked Jack Elliano into making me a pair of 60mA/1KV rated transformers that could swing 600VRMS.It took him several attempts  to come up with a finished product  that he was happy with. Used them briefly for an 813 amp. He put a lot of work into the transformers but only charged his standard "off-the-shelf" price. Probably ought  to put them to work again.  To do this right, a 300B is marginal.Really there's no smaller substitute for an 845 type in this application.

 

Power supply would either be something like a "21st Century Maida Regulator" or something tube regulated with a big pass tube like a 13E1.

 

As an alternative, I was thinking about something balanced with direct-coupled outputs. CCS loaded 801's for outputs. 1st and 2nd stage 4P1l's.1st and 2nd stages direct coupled, caps between the driver 4P1l and the 801's. The EML's would be great here, but at $1k per quad, out of the question for me.

 

 

 

 

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6c33 is also very fuzzy about pretty much everything. 

 

I was thinking of sort of a "poor man's" all DHT amp. 4P1l directly coupled to a 6P21S, then interstage coupled to either an 845 or a GM70. 845 then drives a 1:1+1 output transformer.Run the 845 at a relatively low 600V, 60mA plate current, and 100V fixed bias. A few years ago I talked Jack Elliano into making me a pair of 60mA/1KV rated transformers that could swing 600VRMS.It took him several attempts  to come up with a finished product  that he was happy with. Used them briefly for an 813 amp. He put a lot of work into the transformers but only charged his standard "off-the-shelf" price. Probably ought  to put them to work again.  To do this right, a 300B is marginal.Really there's no smaller substitute for an 845 type in this application.

 

Power supply would either be something like a "21st Century Maida Regulator" or something tube regulated with a big pass tube like a 13E1.

 

As an alternative, I was thinking about something balanced with direct-coupled outputs. CCS loaded 801's for outputs. 1st and 2nd stage 4P1l's.1st and 2nd stages direct coupled, caps between the driver 4P1l and the 801's. The EML's would be great here, but at $1k per quad, out of the question for me.

 

The 6P21S could work as an output tube at just 600V.  Not a whole lot of data on them but it would be doable and quite cheap.  I'd personally go for some nice IDHT on the front end as it's easier to power and the DHT's really need the high frequency filament supplies to behave so they add up quickly. 

 

The 300B is overrated for pretty much everything but I like the challenge of trying to make something of them.  I also have them and pretty much all the parts needed for something like that.  :)  PSU will be a CLCLCRC or something like that with a tube rectifier and all film caps. 

 

The EML's are a bit nuts but also truly great tubes.  Kevin has designed a 12 tube DHT amp which used a quad of 20B's just to drive the output 845's.  Never asked for the schematic of that one as I don't want to see it.  Then I might actually build it...

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I have always been drawn to the eletraprintish* design of a low-to-mid power op amp (like 5-10w) driving a 32:600ohm transformer feeding the grid of a DHT tube.  :indra:

 

I am biased towards push-pull so 2 DHTs in my case, but to each his own. 

 

* If this is not an electraprint design I am sorry and welcome correction. 

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