Remember These?

What people are working on at the moment
Cressy Snr
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#391 Re: Remember These?

Post by Cressy Snr »

OK,
That's the end of the breadboad adventure.
Next the proper build. I'll start a new thread for that.....eventually.
Thank you and goodnight. :)
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Ray P
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#392 Re: Remember These?

Post by Ray P »

Hi Steve. Thinking more on switching from 6SN7 to 6H30pi, because of easier availability, I think I'll use a hole shrinker and use 9pin 6H30pi valves. To that end I've started to rework my input/driver PCB to suit. If you want I'll send you some for your steam punk rebuild - they'll take around three weeks to be fabricated and shipped.

So I can check and finalise the PCB layout can you post a schematic of the circuit you've settled on with the 6H30pi stage?

Cheers
Sorry, I couldn't resist!
Cressy Snr
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#393 Re: Remember These?

Post by Cressy Snr »

Ray P wrote: Thu Jan 24, 2019 8:14 am Hi Steve. Thinking more on switching from 6SN7 to 6H30pi, because of easier availability, I think I'll use a hole shrinker and use 9pin 6H30pi valves. To that end I've started to rework my input/driver PCB to suit. If you want I'll send you some for your steam punk rebuild - they'll take around three weeks to be fabricated and shipped.

So I can check and finalise the PCB layout can you post a schematic of the circuit you've settled on with the 6H30pi stage?

Cheers
There you go:

Image
Yes I wouldn't mind a couple of boards. :)
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Ray P
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#394 Re: Remember These?

Post by Ray P »

Cressy Snr wrote: Thu Jan 24, 2019 12:33 pm There you go:

Image
Thanks Steve. Can I just confirm;
  • the cap between the the two halves of the 6H30pi,correct as 1.0F? Previously you had 0.1uF in tgat position?
  • The 10K resistors connected to the plates of the 6H30pi seemoverrated at 10W?
Sorry, I couldn't resist!
Cressy Snr
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#395 Re: Remember These?

Post by Cressy Snr »

Yes the cap is now 1.0uF and the resistors are 10W.
I like to over rate stuff, but 5W would suffice in the anode resistor positions.
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Cressy Snr
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#396 Re: Remember These?

Post by Cressy Snr »

I'm really going to have to get on with this rebuild into a nice box.
The amp with output transformers is great. Unfortunately I've had to put it out of the way and am now listening to my solid state amps. Trouble with these is they need a speaker that wants current drive on the end of them, not highly efficient single driver speakers that waft along on milliwatts and love voltage drive off tube amps.
Compared to either of the tube amps, the sound is overtight, spiky, angular, jerky and lacking in subtlety and fluidity. Part of me wishes I'd left well enough alone and not been daft enough to build a single tube OTL amplifier, as now I'm not enjoying the music as much, and won't until I've built the 'proper' OTL project. I can't listen to anything without wishing it was coming out of the bloody OTL!
As an example, John Prine's 2005 album "Fair and Square" is magical on the OTL and also to a slightly lesser extent the "Not OTL" positively shimmering and dripping with emotion, harmonically saturated acoustic guitars and of course that world weary voice. It's just fecking ordinary on the solid state stuff. Think I'll turn in for the night.BAH!
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Ray P
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#397 Re: Remember These?

Post by Ray P »

Cressy Snr wrote: Thu Jan 24, 2019 9:04 pm Yes the cap is now 1.0uF and the resistors are 10W.
I like to over rate stuff, but 5W would suffice in the anode resistor positions.
Thanks Steve and I hope you weren't offended by my asking.

I all but finished reworking the PCB layout last evening but got tired so left off in case I made mistakes. More later.
Sorry, I couldn't resist!
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#398 Re: Remember These?

Post by Cressy Snr »

Ray P wrote: Fri Jan 25, 2019 7:07 am
Cressy Snr wrote: Thu Jan 24, 2019 9:04 pm Yes the cap is now 1.0uF and the resistors are 10W.
I like to over rate stuff, but 5W would suffice in the anode resistor positions.
Thanks Steve and I hope you weren't offended by my asking.

I all but finished reworking the PCB layout last evening but got tired so left off in case I made mistakes. More later.
Ho offence taken. :)
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ed
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#399 Re: Remember These?

Post by ed »

Cressy Snr wrote: Thu Jan 24, 2019 10:36 pm It's just fecking ordinary on the solid state stuff. Think I'll turn in for the night.BAH!
priceless!

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Cressy Snr
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#400 Re: Remember These?

Post by Cressy Snr »

Not dissing solid state per se. Of course an amp will 'work' with any speaker, but whether that amp and speaker work as a seamless musical unit is another question. The SS amps I have just seem to work with the Fanes to produce too much of an overdamped presentation.

IMHO you can't talk about amps in isolation as they have to be connected to a speaker and unfortunately, my Fanes, as I've found out seem to work best with single ended valve amplification; OTL or no. TBH I wish I'd had the Fanes, when I was messing about with push pull pentodes a couple of years ago, would probably have been running lovely old KT66s (I bought four off Steve) by now, and happy as a pig in the proverbial. However we are where we are and I wouldn't have discovered that 13E1s done right (ish) could be so bloody fab.

One thing I would definitely like to try with the Fanes would be a Nelson Pass SIT amplifier, or Phil's Pass, 50W SE jobbie. That would be very interesting.
Last edited by Cressy Snr on Fri Jan 25, 2019 11:45 am, edited 1 time in total.
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Nick
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#401 Re: Remember These?

Post by Nick »

Just try adding a resistor in series with the speaker when using solid state.
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#402 Re: Remember These?

Post by IslandPink »

I'd be very interested to hear the result of this tes, Steve/Nick.
What is the spectrum of the distortion at low levels, Nick - did you look at the components ?
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#403 Re: Remember These?

Post by ed »

Cressy Snr wrote: Fri Jan 25, 2019 11:18 am
One thing I would definitely like to try with the Fanes would be a Nelson Pass SIT amplifier, or Phil's Pass, 50W SE jobbie. That would be very interesting.
when I had a plan to build with the fanes I was looking forward to trying the F2...it's the closes I have to the SIT topology....I'm still dreaming...I have 1 2sk82 somewhere but no partner so the only way I'm ever going to taste the real thing is when I can stump up $4000...oh waily waily
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Nick
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#404 Re: Remember These?

Post by Nick »

IslandPink wrote: Fri Jan 25, 2019 12:01 pm I'd be very interested to hear the result of this tes, Steve/Nick.
What is the spectrum of the distortion at low levels, Nick - did you look at the components ?
The interesting thing is the distortion levels are about the same at low levels as higher. Whatever signal you try and pass a valve doesn't like a 8R load on its cathode. It was 2nd highest, then descending with term, 4th seemed to be higher than 3rd if I remember, but it certainly wasn't just low order, but the large amount of 2nd would mask a lot of the higher terms. Depends on the signal I guess, could get messy with Stravinsky for example.
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Cressy Snr
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#405 Re: Remember These?

Post by Cressy Snr »

Aye, the distortion performance was crap at whatever level you cared to dial in. It didn't change in degrees of crapness though.

The drivers were starved of HT however and were contributing a significant amount of distortion to the total once Nick had measured what was going on with them. I'd removed the 300V supply (bad move with a 5687 I later learned) and the performance on music did seem more of a piece, but that, I also learned was more down to a crappy earthing scheme with the two power supplies than the superiority of one. The low HT was the main reason I chose to use the 6H30Pi in the proper build; that, plus the outstanding linearity of this tube. I might now get 1% THD out of the 13E1 into 8 Ohms, with the 6H30Pi as input/driver.

As Nick says, a single valve does not like an 8 Ohm load on its cathode, and though a single 13E1 will do 8 Ohms (unlike the 6C33C) 16 Ohms is really where you want to be with a single tube OTL, so Ray will be fine with his 15 Ohm Lowther horns.

That said, this particular OTL remains the best music machine I've ever heard ....period.
Though whether it'll hold up in the big room at Owston is quite another matter. I'll have to hunt out all my girl, guitar and plinky-plonk bollocks to give it a chance. :lol: :lol:
Oh for a 16 Ohm version of the Fane 12-250TC.
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