Pass DIY Addict
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Hi
I'm a newb on the forum. I was also wondering about preamps, specifically if anyone had tried a Little Bear P-3 (eBay "6N3 + 6Z4 tube valve preamp amplifier class A ", 6N3 6Z4 Tube Valve Preamp Amplifier Class A Inclu Transformer 110V 220V AU | eBay ) with the Amp Camp Amps?
I can't find specs on the output impedance or level of the Little Bear (although I have asked the question of the seller I don't know if I'll get a reply) and whilst I read the ACA has 10kOhm input impedance I don't know what input level voltage it will take.
I also am not sure I am even asking the right question. Can anyone help?
I'm a newb on the forum. I was also wondering about preamps, specifically if anyone had tried a Little Bear P-3 (eBay "6N3 + 6Z4 tube valve preamp amplifier class A ", 6N3 6Z4 Tube Valve Preamp Amplifier Class A Inclu Transformer 110V 220V AU | eBay ) with the Amp Camp Amps?
I can't find specs on the output impedance or level of the Little Bear (although I have asked the question of the seller I don't know if I'll get a reply) and whilst I read the ACA has 10kOhm input impedance I don't know what input level voltage it will take.
I also am not sure I am even asking the right question. Can anyone help?
Update from before:
I purchased two ACA complete kits that were built by a member of another forum. He could not get them working. I figured I would be able to get them playing without much money spent. I figured worst case it would be an IRF240 or small BJT, both of which I had laying around.
The problem ended up being a few cold solder joints on one amp, and the one he could never get working was only a problem with the DC jack being wired up wrong. Long story short, it only required a few easy repairs and now I have a great set of amps I can gift to a friend who always does things for people around him.
They played for about 1 hour last night and got nice and warm. Sounded great!
Steve
I purchased two ACA complete kits that were built by a member of another forum. He could not get them working. I figured I would be able to get them playing without much money spent. I figured worst case it would be an IRF240 or small BJT, both of which I had laying around.
The problem ended up being a few cold solder joints on one amp, and the one he could never get working was only a problem with the DC jack being wired up wrong. Long story short, it only required a few easy repairs and now I have a great set of amps I can gift to a friend who always does things for people around him.
They played for about 1 hour last night and got nice and warm. Sounded great!
Steve
try it and report
though .... without knowing sch I would never buy any kit , especially knowing that 6N3 ( chinese cousin of russian 6N3P) is having too much gain for line stage , for no-feedback use ;
regarding output impedance - there may be cathode follower (mandatory here , to properly drive ACA), but also may be not
go figure
Thanks Zen Mod
I will give it a try, I've had some advice it will likely work so I have put a bid on a Little Bear and am arranging an ACA kit now. Will let forum know how it goes once all the gear in my hands and assembled
Cheers
You can buy it here, the price is OK for the N version...
8 pieces of LSK170 ULTRA LOW NOISE SINGLE N-CHANNEL JFET - Parts
BR,
Eric
8 pieces of LSK170 ULTRA LOW NOISE SINGLE N-CHANNEL JFET - Parts
BR,
Eric
Want to thank Nelson for this very special amp. It sounded very good with laptop PSU. I am still experimenting with one channel only and am powering a pair of Fostex 168Sigmas. I tried 16 ohms load to begin with but have now switched to 4 ohms.
I was so pleased with the sonics that I wanted to try a linear PSU. I wanted to use what I've got.
So now I have the ACA powered with 33VDC and a 2k2 resistor drop for Q4. Rectifier is a 35Amp bridge; CRC filter is 10,000uF + 4,700uF - 2E2 x 8 in parallel on both the +ve supply and ground lines - 10,000uF +4,700uF. 10uF MKP caps decouple Q2 and Q4, very close to their Drain pins. C3 is also MKP.
2k2 resistor mod between EB of Q3 is in place. R1, R2 is 1E5 x 6 in parallel and R3, R4 is 2E2 x 9 in parallel.
Drain of Q1 is set at 10V. Offset after C1 is 11mV.
Have not yet measured the actual current consumption. But I should say it sounds phenomenal. Compared to original values for R1-R4, Bass and Mid-bass is tighter, more defined, better slam and subjectively "faster". Voices are also more refined and defined. Highs are more separated. Original values for R1-R4 made the sound softer and subjectively "slower". With no access to measuring equipment, my guess is that H3 is near equal to H2 with my mods, whereas it is predominantly H2 with the original values.
The heatsink measures 12"x8"x1.50", but boy, does it run hot?!! So I am thinking of dropping the heatsinks to 12"x4"x1.25" and blow some slow running fans. R1-R4 and the PSU resistors are also very warm, so a fan will help overall.
Just wanted opinions of more experienced builders.
(P.S. I hope to test this against the VSSA kit amp by Lazy Cat, which started in the Solid State Forum and was later moved to the Vendors Bazaar.)
I was so pleased with the sonics that I wanted to try a linear PSU. I wanted to use what I've got.
So now I have the ACA powered with 33VDC and a 2k2 resistor drop for Q4. Rectifier is a 35Amp bridge; CRC filter is 10,000uF + 4,700uF - 2E2 x 8 in parallel on both the +ve supply and ground lines - 10,000uF +4,700uF. 10uF MKP caps decouple Q2 and Q4, very close to their Drain pins. C3 is also MKP.
2k2 resistor mod between EB of Q3 is in place. R1, R2 is 1E5 x 6 in parallel and R3, R4 is 2E2 x 9 in parallel.
Drain of Q1 is set at 10V. Offset after C1 is 11mV.
Have not yet measured the actual current consumption. But I should say it sounds phenomenal. Compared to original values for R1-R4, Bass and Mid-bass is tighter, more defined, better slam and subjectively "faster". Voices are also more refined and defined. Highs are more separated. Original values for R1-R4 made the sound softer and subjectively "slower". With no access to measuring equipment, my guess is that H3 is near equal to H2 with my mods, whereas it is predominantly H2 with the original values.
The heatsink measures 12"x8"x1.50", but boy, does it run hot?!! So I am thinking of dropping the heatsinks to 12"x4"x1.25" and blow some slow running fans. R1-R4 and the PSU resistors are also very warm, so a fan will help overall.
Just wanted opinions of more experienced builders.
(P.S. I hope to test this against the VSSA kit amp by Lazy Cat, which started in the Solid State Forum and was later moved to the Vendors Bazaar.)
I'm surprised to see it run so hot with such big heatsinks, I have built the regular ACA with a 1A bias and 19Vdc supply and I can touch my heatsink without any problem and they are only 8"x3"x 2" / channel.
Keep us posted.
Eric
Is yours with the resistor mod? With the resistor mod and R3, R4 being a little lower than R1, R2, the sound was very detailed and defined, but the 12"x4"x1.25" heatsinks got pretty hot.
I think I like H3 being just a tad bit lower than H2 because I enjoy the definition and musicality at the same time. H2 being dominant as in the stock ACA is more relaxed, laid back, ever so slightly undefined in the bass and mid-bass and a bit subjectively slow.
I think I like H3 being just a tad bit lower than H2 because I enjoy the definition and musicality at the same time. H2 being dominant as in the stock ACA is more relaxed, laid back, ever so slightly undefined in the bass and mid-bass and a bit subjectively slow.
does this mean that your " improved " amps are now for sale? I'm not far away, just next door really........
John
Hey DIY Gurus,
How about using the BC337-40 instead of ZTX450s?
here is the data sheet :
http://lipid.biocomp.unibo.it/~raffo/Solar/343-16444-0-BC337.pdf
It was a suggestions from someone, thought i'd run it down through the gurus here
cheers!
How about using the BC337-40 instead of ZTX450s?
here is the data sheet :
http://lipid.biocomp.unibo.it/~raffo/Solar/343-16444-0-BC337.pdf
It was a suggestions from someone, thought i'd run it down through the gurus here
cheers!
just go for it , taking care of pinout
not a Guru , just ZM
Thanks Zen Mod. i'll hook it up and see how it works
