Still need to fit the switch to allow the bias current meter to work, but other than that all complete.
Tried out some KT88's they sound even better. Was not expecting to hear any difference, but it's quite noticeable. B+ 460v 80mA bias
Hi Ian, its amazing that you're getting 460 B+ on 360v secondaries, running at 80ma. Is that SS or tube rectifier ?
Bit of a story to that.
You would be correct but....
I had a choice of either 220 or 230v primary to a single 360-0-360v. Here we are actually a touch above 240v at the socket (I measured it). So in the end I picked the 220v primary which combined with my higher mains voltage boosts the output to more like 395-0-395 from the transformer.
You would be correct but....
I had a choice of either 220 or 230v primary to a single 360-0-360v. Here we are actually a touch above 240v at the socket (I measured it). So in the end I picked the 220v primary which combined with my higher mains voltage boosts the output to more like 395-0-395 from the transformer.
Ok, makes sense. Here, our mains are supposedly rated at 230v, but 240-250v is very common in the evenings. I messed up the mains trafo on two builds before getting a servo stabilizer. Have had no problems since then.
Even the trafo in the "Elekit 8200" build got super hot during those 'swinging' days 😀
Even the trafo in the "Elekit 8200" build got super hot during those 'swinging' days 😀
We often have 250 to 254 volts (127-0-127) here on days like today when neither heat or air conditioning are running. The pole transformer that feeds 9 houses in in my yard, so we are the closest house to the transformer. It makes the 2004 vintage Hammond made Allied 6K7VG transformer with a 117 volt primary get too hot to touch after a few hours of continuous use, but it has run fine for over 15 years.
Btw, I get 360 B+ with 300v secondaries & SS rectifier. With 350v & valve rectifier I get 410v B+, SS is not tried yet
Running KT88s I found the bass to be a bit thin. Upping the coupling capacitors from .22 to .66 really made a big improvement for me. Much prefer the KT88s now over the EL34s on this amp.
Have you tried running it in Ultra Liner with the cathode feedback engaged?
I found the bass to be pretty intense with KT88s in that format (I have the big CXSE Edcors). Even with my Yamaha NS1000s which are not a bass heavy speaker by any stretch.....
I found the bass to be pretty intense with KT88s in that format (I have the big CXSE Edcors). Even with my Yamaha NS1000s which are not a bass heavy speaker by any stretch.....
Yeah that's how I run it all the time.
Could be my opt's are not as good as yours, but this little mod seems to have helped - so I dunno ??
Could be my opt's are not as good as yours, but this little mod seems to have helped - so I dunno ??
Okay, found my issue.... Had a fault in my subwoofer which takes it's input from the output of the volume control of my amp. Fixed fault and removed extra capacitance from the coupling capacitors and all is running like a dream now.
Today I retrofitted a cathode feedback switch.
I don't really hear much difference with it off (previously had it hardwired on permanently)
This is in triode more, which has now become my preferred listening since yesterday 🙂 when I added a switch for it.
Is there anything in particular I should be listening for / hearing?
Cheers
I don't really hear much difference with it off (previously had it hardwired on permanently)
This is in triode more, which has now become my preferred listening since yesterday 🙂 when I added a switch for it.
Is there anything in particular I should be listening for / hearing?
Cheers
Will SSE handle 5U4 or 5Y3? I have some in my stash.
Also, looking at rectifiers for the SS and switch, there are $2 and $3 standard and $12 and even $18 silicon carbide? Any reason to go up market?
Also, looking at rectifiers for the SS and switch, there are $2 and $3 standard and $12 and even $18 silicon carbide? Any reason to go up market?
112-VS-E5TX0812-M3-ND
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My build has a 47uF first cap and 50R thermistor on the B+ center tap. The mains transformer secondary is 75R. I've tried 5V4G (Brimar brown base) and 5U4GB (N.E.C & Radiotron). They both work fine.
I see a 'tineee' delay on start-up, when compared to a GZ34 which takes ~ 8-10 secs to ramp up.
I see a 'tineee' delay on start-up, when compared to a GZ34 which takes ~ 8-10 secs to ramp up.
Choice of rectifier tube will affect the b+ voltage. They all loose (or drop) some voltage. Ideally you want the lowest possible voltage drop. That said provided they are octal socketed and support your line AC voltage any will work.
You want good quality fast switching diodes.
I use a gz34 which drops less voltage. I have diode rectification in place, but never use it. I intend it to be a fall back in the case that my rectifier tube fails and 8 do not have one to hand.
The 5U4 will work but provide slightly less B+ voltage. A 5Y3 will be running over its spec for most tube choices except the 6V6GT. Some may work, but some will spark out on startup.
I have been using the DSA-1-18D diodes primarily because they survived the lightning induced line voltage spikes in Florida, but they are not in stock at the usual places now.
My problem SSE has been up and running for a couple of weeks. All it took was a new power transformer, the original from my first build almost 20 years ago, an Allied, quit. The center tap wasn't center tapping.
I've been snakebit these past few months, first one of my mono blocks failed which is why I built this new SE. Then, during the build, one of my 15 year old 4Pi Pros had it's JBL 2226 woofer blow. It's 16 Ohm and no one has a recone kit. I thought about a new pair of 2226H 8 Ohm, but the rather costly crossover parts are for 16. and a pair would be $1,000 plus new parts.
So I ordered a pair of Wharfedale Diamond 12.4s which arrived today. They sound great and the SSE has no problems even on large orchestral. I had been somewhat dissatisfied with the Gold Lion KT66 I included in the build sounding a little too romantic in the mids for my taste. That carried over into the Diamonds so I pulled a pair of GL KT 88s which sound great in the monos and that made the SSE/Diamond combo just right.
They're too high up perched on the sand boxes I had the Pi's sitting on which I'll fix as soon as I get some help to move them onto the spiked outriggers they came with. It was all 75 year old me could do to slide them onto the sand boxes and get them upright ;-)
I've been snakebit these past few months, first one of my mono blocks failed which is why I built this new SE. Then, during the build, one of my 15 year old 4Pi Pros had it's JBL 2226 woofer blow. It's 16 Ohm and no one has a recone kit. I thought about a new pair of 2226H 8 Ohm, but the rather costly crossover parts are for 16. and a pair would be $1,000 plus new parts.
So I ordered a pair of Wharfedale Diamond 12.4s which arrived today. They sound great and the SSE has no problems even on large orchestral. I had been somewhat dissatisfied with the Gold Lion KT66 I included in the build sounding a little too romantic in the mids for my taste. That carried over into the Diamonds so I pulled a pair of GL KT 88s which sound great in the monos and that made the SSE/Diamond combo just right.
They're too high up perched on the sand boxes I had the Pi's sitting on which I'll fix as soon as I get some help to move them onto the spiked outriggers they came with. It was all 75 year old me could do to slide them onto the sand boxes and get them upright ;-)