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Re: Remember These?

Posted: Sat Jan 12, 2019 11:11 pm
by Cressy Snr
Ray P wrote:
Sat Jan 12, 2019 11:00 pm
Are we due another schematic Steve - as you're going to box it? I'll unashamedly plaigerise your work!
Aye, once I've worked out the new 6C30pi input and driver stage.

Re: Remember These?

Posted: Sat Jan 12, 2019 11:16 pm
by Ray P
Cheers Steve. I think you mean 6h30pi?

Re: Remember These?

Posted: Sat Jan 12, 2019 11:20 pm
by Cressy Snr
Ray P wrote:
Sat Jan 12, 2019 11:16 pm
Cheers Steve. I think you mean 6h30pi?
Er yes :oops:

Re: Remember These?

Posted: Sat Jan 12, 2019 11:24 pm
by Ray P
BTW, the 6H30pi was also used as the input/driver in the original Transcendent SE-OTL. I'll hazard a guess that the circuit for the stage will be the same in the Minibeast.

Re: Remember These?

Posted: Sat Jan 12, 2019 11:29 pm
by Ray P
Cressy Snr wrote:
Sat Jan 12, 2019 11:20 pm
Er yes :oops:
I used to get confused with the SE-OTL, which used parallel 6C19pi for its output.

Re: Remember These?

Posted: Sun Jan 13, 2019 11:56 am
by Cressy Snr
Mike H wrote:
Sat Jan 12, 2019 10:41 pm
Plenty of variety then! :D
There's always plenty of variety at Nick's :)

Re: Remember These?

Posted: Sun Jan 13, 2019 12:54 pm
by Ray P
Are you planning to try the 6H30pi on your breadboard Steve?

Re: Remember These?

Posted: Sun Jan 13, 2019 1:36 pm
by Cressy Snr
Ray P wrote:
Sun Jan 13, 2019 12:54 pm
Are you planning to try the 6H30pi on your breadboard Steve?
Not decided yet. I think the breadboard is coming very close to having served its purpose. It would involve a complete rebuild of the whole front end, including the heater wiring as the 5687 and its relatives has a different pinout to most of the rest of the 9 pin noval world.

I know how it sounds in the MiniBeast I built for Nigel, so there's probably not a great deal of point continuing the breadboard.
We'll see when they arrive next week.

Re: Remember These?

Posted: Sun Jan 13, 2019 1:49 pm
by izzy wizzy
Cressy Snr wrote:
Sun Jan 13, 2019 1:36 pm
Ray P wrote:
Sun Jan 13, 2019 12:54 pm
Are you planning to try the 6H30pi on your breadboard Steve?
Not decided yet. I think the breadboard is coming very close to having served its purpose. It would involve a complete rebuild of the whole front end, including the heater wiring as the 5687 and its relatives has a different pinout to most of the rest of the 9 pin noval world.

I know how it sounds in the MiniBeast I built for Nigel, so there's probably not a great deal of point continuing the breadboard.
We'll see when they arrive next week.
As it is completely different, wouldn't that be a good reason to bread board it? You'll probably end up with different feedback too as well as maybe different anode loads, bias resistors blah blah. May as well keep us entertained for a bit longer ;)

Cheers,
Stephen

Re: Remember These?

Posted: Sun Jan 13, 2019 1:51 pm
by pre65
Cressy Snr wrote:
Sun Jan 13, 2019 1:36 pm
Ray P wrote:
Sun Jan 13, 2019 12:54 pm
Are you planning to try the 6H30pi on your breadboard Steve?
I know how it sounds in the MiniBeast I built for Nigel, so there's probably not a great deal of point continuing the breadboard.
That's what breadboards are for. :wink:

Re: Remember These?

Posted: Sun Jan 13, 2019 3:01 pm
by Wolfgang
The best part of using the 6H30 is that it ca be easily replaced by a 6H6p or 6H1p and more. My guess is, from listening to all 3 tubes in my sound systems (AR, SE OTL ), that a 6H30 might sound too sterile in a single output tube OTL. The 6H6p might sound warmer with more bass, the 6H1p a little more open in the upper mids with a little less punch in the bass than the 6H6p.The 6H6p needs double the heater current if tube rolling should be an option. But they are drop in replacements.
However, with some special attention to what the 6H30 needs in order to sound best it can be an exiting experience. With how much current and at which voltage the 6H30 is used will decide how good or boring it will sound. Lots of experimenting and listening.

Re: Remember These?

Posted: Sun Jan 13, 2019 7:37 pm
by Cressy Snr
Did a bit of scoping early this morning. I thought I'd have another look after fitting the 5687s from Nick.
Also I put the idle current back to half an amp (520mA, up from 460mA) by putting in my original 2R4 programming resistors. I also sognificantly reduced the amount of feedback.

I was able to get to around 0.7 clean Watts before it started clipping.
Might not sound like much but it's remarkably good for a single tube without OPT, into 8 Ohms and it's more than it was putting out clean yesterday. We did, just about manage 1W, yesterday but the distortion was 10%. :( OK, some of that was down to duff drivers but hardly inspiring.

However with my 8 Ohm single driver speakers being 98dB efficient, the lack of power is not a handicap. Nevertheless, the case for 16 Ohm speakers is strong. :)

Re: Remember These?

Posted: Sun Jan 13, 2019 7:48 pm
by Cressy Snr
Oh and it was great to see Dave and Meredith, this afternoon. Some great music and great company. :)

Re: Remember These?

Posted: Sun Jan 13, 2019 8:08 pm
by Cressy Snr
Wolfgang wrote:
Sun Jan 13, 2019 3:01 pm
The best part of using the 6H30 is that it ca be easily replaced by a 6H6p or 6H1p and more. My guess is, from listening to all 3 tubes in my sound systems (AR, SE OTL ), that a 6H30 might sound too sterile in a single output tube OTL. The 6H6p might sound warmer with more bass, the 6H1p a little more open in the upper mids with a little less punch in the bass than the 6H6p.The 6H6p needs double the heater current if tube rolling should be an option. But they are drop in replacements.
However, with some special attention to what the 6H30 needs in order to sound best it can be an exiting experience. With how much current and at which voltage the 6H30 is used will decide how good or boring it will sound. Lots of experimenting and listening.
Thanks for the heads up on the 6H6P and 6H1P Wolfgang.

Re: Remember These?

Posted: Mon Jan 14, 2019 1:14 am
by Thermionic Idler
Cressy Snr wrote:
Sun Jan 13, 2019 7:48 pm
Oh and it was great to see Dave and Meredith, this afternoon. Some great music and great company. :)
Cheers Steve, it was a great way to spend a windy Sunday afternoon, thanks so much for your hospitality, and the tea, and the cheese and biscuits - all were delicious!

It's quite amazing, hearing to what extent a room can be filled with three quarters of a watt. I rather envy you that amplifier, I definitely think you have a winning combination there. I'm wondering to myself how many 13E1's it would take to get to the equivalent of my 12xEL509 per side output stage. And whether it would cost more or less than buying 24 EL509's!!

Academic really as I'm rather committed at this point, although given that a second supplier has also entirely failed to deliver my order for the output valves that they promised me in November would be coming in 2 weeks - I'm starting to wonder if it might not actually be easier to get hold of the bloody 13E1's instead. They didn't respond to my chase-up email last week so I've just now read them the riot act and threatened action via PayPal unless they respond, so we'll see what happens.

End of thread hijack, as you were.