I made my first ever online order for a tube project some 4 years ago. That order is for a JE Labs 2A3 which was sent to Angela.com which also contained a pair of 8532 and 1626 - parts for the Darling amp.
I haven't put those tubes to use since the order arrived.
Yesterday, while I was waiting for my students to finish ther labs, I started scribbling something, which ended up like this-
(photo was taken after I completed the amp)
I haven't put those tubes to use since the order arrived.
Yesterday, while I was waiting for my students to finish ther labs, I started scribbling something, which ended up like this-
(photo was taken after I completed the amp)
Attachments
My chassis has only one hole sized for for a 9-pin tube, so I cannot use my 8532 on this circuit, as they're 7-pin and single triode. My bias towards the 407A sonics on my preamp led me to use a close "cousin" - the 2C51 (while I also have the Western Electric 396A, it will be put to service later) which is a 9-pin dual triode with 6.3V filaments (unlike the 20/40V of the 407A).
I got good results using the diyAudio CCS in my other project, so why not use it again. While my "RS Components design tool" shows the CCS set at 8mA, the actual circuit had 10mA because I don't have a 125R resistor. Tonight, I will put in a Bourns multi-turn variable resistor so I can dial it in at 8mA.
SY was a big influence on my choice with regards to biasing, so the 2C51 was biased using Yellow LEDs which should give me 2V or so.
I decided not to re-invent the wheel and went ahead with the original bias scheme of the 1626- a shared 500R, bypassed by a capacitor.
I have some left-over power transformer and output transformers (5K:8/16R) from a previous 807 project which I re-used for this amp.
Just before midnight I was able to complete assembly, did some voltage measurements which came very close to my scribble. With that, I hooked it up to my speakers and played some music.
I got good results using the diyAudio CCS in my other project, so why not use it again. While my "RS Components design tool" shows the CCS set at 8mA, the actual circuit had 10mA because I don't have a 125R resistor. Tonight, I will put in a Bourns multi-turn variable resistor so I can dial it in at 8mA.
SY was a big influence on my choice with regards to biasing, so the 2C51 was biased using Yellow LEDs which should give me 2V or so.
I decided not to re-invent the wheel and went ahead with the original bias scheme of the 1626- a shared 500R, bypassed by a capacitor.
I have some left-over power transformer and output transformers (5K:8/16R) from a previous 807 project which I re-used for this amp.
Just before midnight I was able to complete assembly, did some voltage measurements which came very close to my scribble. With that, I hooked it up to my speakers and played some music.
Attachments
Like most of my projects, there are no exotic parts, even though I'm tempted to use my Riken resistors and MultiCap RTX coupling caps.
You'll see on the photo that my 1626 cathode capacitor is a white-coffin bypassed with a generic 220uF electrolytic. The coupling caps are Auricaps, and the power supply is a simple CRCRC with generic electrolytics and white coffin as well.
By the way, there's 1K grid stopper to the grid of the 1626 (not in schematic) because my 220K grid leak resistors have too short leads
So how does it sound? It has a different character which I tend to like, sweet and mellow, for a change. I can't play really loud as my neighbors might complain but the vocals reproduction is glorious. It does not have the punch and kick of my 2A3 or 45, but it does bass deep enough to give me some satisfaction.
You'll see on the photo that my 1626 cathode capacitor is a white-coffin bypassed with a generic 220uF electrolytic. The coupling caps are Auricaps, and the power supply is a simple CRCRC with generic electrolytics and white coffin as well.
By the way, there's 1K grid stopper to the grid of the 1626 (not in schematic) because my 220K grid leak resistors have too short leads
So how does it sound? It has a different character which I tend to like, sweet and mellow, for a change. I can't play really loud as my neighbors might complain but the vocals reproduction is glorious. It does not have the punch and kick of my 2A3 or 45, but it does bass deep enough to give me some satisfaction.
Attachments
Great job on the amp, nice, simple yet elegant. I have parts to build a Darling so one of these days, month or years I will get to it... 🙂
Regards,
Sal Brisindi
Regards,
Sal Brisindi
That amp looks great!
Is the 2C51 similar to 5670? How much voltage swing you need to drive the 1626?
I would like to make one like your Darling!
Arnold, question: which in your opinion would sound better a 1626 or a 12b4 flea powered amp? Thanks.
Is the 2C51 similar to 5670? How much voltage swing you need to drive the 1626?
I would like to make one like your Darling!
Arnold, question: which in your opinion would sound better a 1626 or a 12b4 flea powered amp? Thanks.
Hi Sal, yes, it took me four years to do this 😀
Hi Alex, you're right about 5670. I just need some 60Vp-p to drive the 1626.
On the 1626 vs. 12B4, I can't comment because have not made a 12B4 amp yet, but you're tempting me. However, the 1626 with its ST-bottle is physically very attractive for me 😉
Hi Alex, you're right about 5670. I just need some 60Vp-p to drive the 1626.
On the 1626 vs. 12B4, I can't comment because have not made a 12B4 amp yet, but you're tempting me. However, the 1626 with its ST-bottle is physically very attractive for me 😉
alexg said:
I know you like the 12b4 and I thought about you yesterday while looking at a 12b4 amp circuit, producing almost same power as the 1626. 😀
arnoldc said:
I have not seen the one with the 6au6 driver, the one I was looking at is driven by half a 12ax7. It said to produce 0.9watt.
Am really tempted to do this 12b4 amp.
😀
arnoldc said:
I believe he did. His impression of the quality of the sound, conforms with the opinions I read about the 12b4 on preamp duties, transparent and uncolored.
I'm just curious because, the 12B4 has low Rp and he used 24K (not sure) OPT primary.
The 6AU6->12B4 I mentioned used 5K OPT.
Why not make one, tonight!
😀
The 6AU6->12B4 I mentioned used 5K OPT.
Why not make one, tonight!
😀
I've got the 2nd Abraxas 12B4. You can see it here:
http://www.pedalforroses.homestead.com/PowerAmps.html
I've heard the 1st one as well (the one on his website) on a set of PAWO's utilizing a DCA 4" speaker. It sounded very good! I've also heard my 12B4 side by side with Jef's D5 Darling on my Pi Two Speakers.
The 12B4 has a much tighter bass and clearer high end to my ears. The Darling did vocals a little better and the overall sound was a little more "wooly" for lack of a better term. Both sounded great though, just different.
My 12B4 uses a 14K primary on the OPT's.
I've got all the parts but a chassis and OPT's to do a 5Y3 rectified Darling using a 5965 driver. I really need to finish it.
http://www.pedalforroses.homestead.com/PowerAmps.html
I've heard the 1st one as well (the one on his website) on a set of PAWO's utilizing a DCA 4" speaker. It sounded very good! I've also heard my 12B4 side by side with Jef's D5 Darling on my Pi Two Speakers.
The 12B4 has a much tighter bass and clearer high end to my ears. The Darling did vocals a little better and the overall sound was a little more "wooly" for lack of a better term. Both sounded great though, just different.
My 12B4 uses a 14K primary on the OPT's.
I've got all the parts but a chassis and OPT's to do a 5Y3 rectified Darling using a 5965 driver. I really need to finish it.
Hi Arnold,
Take a look at the dc darling sometime I think you'll find it an even better performer than the standard ac coupled darling. Another possibility is to run you current 1626 design with fixed bias and eliminate the wonky cathode bypass cap.. (My preferred choice in all amp designs.)
Very nice job by the way. 😀
Another very nice tube to experiment with in the sub 1W class is the 171 or 71A, may be a little hard to find, but very nice sound. I drive a pair with led bias choke loaded 5842 in my flea power headphone amplifier.
Take a look at the dc darling sometime I think you'll find it an even better performer than the standard ac coupled darling. Another possibility is to run you current 1626 design with fixed bias and eliminate the wonky cathode bypass cap.. (My preferred choice in all amp designs.)
Very nice job by the way. 😀
Another very nice tube to experiment with in the sub 1W class is the 171 or 71A, may be a little hard to find, but very nice sound. I drive a pair with led bias choke loaded 5842 in my flea power headphone amplifier.
arnoldc said:
Am still debating if I want to do the Darling or the 12B4.
Can't make it tonight, don't have the tubes and the OPT! 😀
All I have are some 6n1p, 12au7, 6dj8, 12j5 and 5670. I will have a pair of 12b4 next week though, I can "borrow" my SE KT88 OPT (5K primary) and borrow my 832A power transformers. 🙂
BTW, am trying to look for the 6AU6->12B4 amp on the net, can't find it. Can you point me to the site? Thanks.
bloozestringer said:
Hi, thanks for the comparative overview between the Darling and 12B4. I'll ask my transformer winder to make me one with 14K primary. Nice amp you got there too.
kevinkr said:
Thanks Kevin, and you know what? I've been searching for the 71A! No luck so far.
Last night I was listening to my Darling and on most of my music, it's running out of dynamics, it's just too mellow for me.
I've heard a friend's Darling and DC Darling and I preferred the DC version myself. But yes, why not? I haven't made a fixed bias amp in my life
so why not this one. Yes!alexg said:
Make both and compare! That schema is on my offline storage. I'll email it to you later.
This is the nice part of having a speaker that can be driven by half a watt. I can try all flea-powered amps with gusto.
The 12B4 sounds really excellent in parafeed mode using cheap line output transformers (10W or 15W) and a decent choke (handmade H3007 or Magnequest BCP-15 - the hammond 157G will also work). With 7-8k line transformers run it around 225 - 240B+ with a 1.2k cathode resistor - the 6au6 version operating point is a bit too low.
As previously mentioned, it has an entirely different sound to the darling. Very clear and punchy with a surprisingly potent bottom end.
As previously mentioned, it has an entirely different sound to the darling. Very clear and punchy with a surprisingly potent bottom end.
arnoldc said:
Go Arnold GO, you know you want to do it! 😀
I am already talking to Edrel for the irons of a parafeed 12b4. 😉
Thanks for the encourgment, Alex 😀 😀
I'd like to do a Parafeed without the plate choke to keep things small. Again, I'd like to use the diyAudio CCS for ths duty. I hope it works 😀
If this works, then I can parafeed my 417A headphone amp also 😎
I'd like to do a Parafeed without the plate choke to keep things small. Again, I'd like to use the diyAudio CCS for ths duty. I hope it works 😀
If this works, then I can parafeed my 417A headphone amp also 😎
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