These ideas are similar to my thoughts several weeks ago when I ordered some ST version 01a's. It seemed like, they are newer manufacture so likely to have better vacuum and consistency, less microphonic due to the ST bulb, etc. Haven't had enough time testing them yet but hoprefully this weekend. I will report anything useful.
John
John
I only have four 01As, all globes. They have different gain, so balance matching is interesting. The motorbike season is almost over, so I will get back to electronics this winter, and try some STs.
I built the UV-201a preamp breadboard in a final version with a machined 4mm anodised top plate and a walnut wooden frame:
UV-201a final version – finished! – Bartola(R) Valves
I love this stage, honestly. With the teflon sockets bolted directly to the top plate, there is barely no microphonic noise. No need to add any damping or silent block.
The sound is extremely clear, a level of detail that you can only get with some DHTs, VT-25 and 01a are my prefered ones I have to say.
Now, time to enjoy it:
Cheers,
Ale
UV-201a final version – finished! – Bartola(R) Valves
I love this stage, honestly. With the teflon sockets bolted directly to the top plate, there is barely no microphonic noise. No need to add any damping or silent block.
The sound is extremely clear, a level of detail that you can only get with some DHTs, VT-25 and 01a are my prefered ones I have to say.
Now, time to enjoy it:
Cheers,
Ale
Hi Ale,
Are these tiny TO220 heatsinks -in CF board- enough for 0.8...1.1W dissipation?
I usually use my C2M SiC CF with 5mA CCS (B+: 220..450V), minimum with Fischer SK437..454 (or greater) heatsinks.
Hi Bela
Yes, they are. These are 6.4C/W ones 37mm tall:
http://uk.farnell.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=10001&langId=44&urlRequestType=Base&partNumber=1703170&storeId=10151
Cheers
Ale
Yes, they are. These are 6.4C/W ones 37mm tall:
http://uk.farnell.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=10001&langId=44&urlRequestType=Base&partNumber=1703170&storeId=10151
Cheers
Ale
Hi Douglas
I tried using a 12V cell to bias top device. It improves the frequency response but not noticeable to sound. In fact using an IXTP08N100D as top device provides the best combination to maximise VDS of lower device. This way it performs really well and sounds better. I have also build a CCS version with mu-follower output as well and tried it. I preferred the gyrator one. Taking the output from the anode increased the distortion as the triode is loaded with the output load as well and not isolated with the bootstrapped mu resistor. With higher distortion, the sound is warmer but less transparent to my ears. It’s a matter of taste. If you want more H2, there you go.
Cheers
Ale
I tried using a 12V cell to bias top device. It improves the frequency response but not noticeable to sound. In fact using an IXTP08N100D as top device provides the best combination to maximise VDS of lower device. This way it performs really well and sounds better. I have also build a CCS version with mu-follower output as well and tried it. I preferred the gyrator one. Taking the output from the anode increased the distortion as the triode is loaded with the output load as well and not isolated with the bootstrapped mu resistor. With higher distortion, the sound is warmer but less transparent to my ears. It’s a matter of taste. If you want more H2, there you go.
Cheers
Ale
Andy, have you tried the mu-follower CCS load not operating as a gyrator? as in missing all that voltage setting stuff. It just seems to me that improving the CCS with some battery bias( say with a DN3545N3 on the bottom ), would work quite well...
cheers,
Douglas
I think Ale has answered you pretty well here. I'm on a plate choke expedition right now. I've been putting 2 of the Hammond 126C interstages in series and getting much better sound than a single one. Works nicely with the 10Y, and I really must try it with the 01A. I may also invest in an amorphous plate choke at some point. Will report the results if and when.
My plate choke quest has taken me back to an old friend from 8 years ago - two Hammond 156C in series. These are fastened bottom-to-bottom and connected out of phase. I was originally using these with the 26 which is another option, but this time I used 01As. I think I gave up on this before because I was getting hum. This time - miraculously - no hum at all.
This is good news for me, for a start, because I have several of them. And also because they sound really good. We have 300H here, so no shortage of Henries for the 01A. Sound is very clear and detailed. I've been using 2 x 126C in series with the 10Y, and I'll also try that with the 2P29L. They're good too and they can take 15mA instead of the 8mA for the 156C. Not much to choose between these options in terms of sound - both very good. I've just got this up and running so extended listening will tell me more, but I'm pleased with this. These chokes are also really, really cheap to buy. Nice result!
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01A preamp completed
First and foremost, thank you Andy and Ale for all your help. The 01A is a beautiful sounding preamp but very difficult to keep quiet. I purchased several tubes(globes) just to find a couple that were not microphonic. The ST tubes however are very quiet along with the 112a tube. My next mod is to remove the resistive pot at the input and install Dave Slagles AVC at the output of the preamp. This should definately bring this preamp to new levels. At unity gain, it will also give me about 600ohms out which is great news for driving longer cables. Also, at 140Henry, the bass is still very good according to my LTSpice model. As of now, this preamp smokes my Audio Research SP6, cant wait to hear it with the AVC!
First and foremost, thank you Andy and Ale for all your help. The 01A is a beautiful sounding preamp but very difficult to keep quiet. I purchased several tubes(globes) just to find a couple that were not microphonic. The ST tubes however are very quiet along with the 112a tube. My next mod is to remove the resistive pot at the input and install Dave Slagles AVC at the output of the preamp. This should definately bring this preamp to new levels. At unity gain, it will also give me about 600ohms out which is great news for driving longer cables. Also, at 140Henry, the bass is still very good according to my LTSpice model. As of now, this preamp smokes my Audio Research SP6, cant wait to hear it with the AVC!
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01A ST Tube question
Hi Guys I’ve started to collect ST 01a in ln preparation to build a pre amp. Bought them in Ebay, though brands are the same, I’ve noticed that the mica plate at the top of the tube have varied shapes, so my question is even if they’re a closely matched, will there be a difference in sound between tubes due to the different design of the mica plate.
Thks
Hi Guys I’ve started to collect ST 01a in ln preparation to build a pre amp. Bought them in Ebay, though brands are the same, I’ve noticed that the mica plate at the top of the tube have varied shapes, so my question is even if they’re a closely matched, will there be a difference in sound between tubes due to the different design of the mica plate.
Thks
I was sent a couple of pairs of amorphous core plate chokes to evaluate by NP Acoustics in Vietnam
- 40mA, 180H, 1150R
- 15mA, 136H, 2100R
I only have a few hours on each, but this is telling me I just love the 15mA one. I need to go back to the 40mA one again - that was good too. Using these with 2P19L at 13mA, 165v, -11v. I'm seriously impressed - the sound is lovely. I have Lundahl and various other plate chokes but first impressions are that these are better. Need to do a more detailed comparison - this is just a thumbs up.
They can make anything you want in terms of specification, and are very friendly and helpful. Amorphous makes a difference here, I feel.
- 40mA, 180H, 1150R
- 15mA, 136H, 2100R
I only have a few hours on each, but this is telling me I just love the 15mA one. I need to go back to the 40mA one again - that was good too. Using these with 2P19L at 13mA, 165v, -11v. I'm seriously impressed - the sound is lovely. I have Lundahl and various other plate chokes but first impressions are that these are better. Need to do a more detailed comparison - this is just a thumbs up.
They can make anything you want in terms of specification, and are very friendly and helpful. Amorphous makes a difference here, I feel.
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I need 15mA to drive my output section of 4P1L PSE. I just use 2 stages. So not using the 01A right now. I hope to put the plate chokes up against other options including the gyrator, but using the 2P29L. That should be informative. We're all after the best alternative, though the answer may well turn out to be "good in different ways".
Here is the best way to go into A2 territory:
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