Hesitate to ask for fear of being flamed, but…
I’m building Pass ACA mono blocks to mate w/ some of the single full range driver speakers I have built, so I need a pre. I use a passive pre w/ the Dynakitparts ST-35 I built a few tears ago, but the input impedance of the ACA seems too low for this approach.
I’m not a hard-core electronics guy like most of you, nor do I have lots of cash for this project. So I want to do something quick dirty to get up & running. There are some folks on another site who seem to like the SainSmart 6N3, so I ordered one. (see: http://www.amazon.com/SainSmart-Ass...qid=1463360213&sr=8-1&keywords=sain+smart+6n3 ) I also picked up some NOS GE JAN 5670w tubes to use in place of the stock Chinese tubes.
My concern is that the transformer is labeled as 110 v. input. My wall sockets measure 124 v. (most of the time). Output from the transformer measures correspondingly more than the 6.3 v. for the heaters and 170 v. for the plates.
What to do?
1) Use it ‘as is’ & burn through tubes?
2) buy a new transformer? buy a step down transformer? (but I have no clue what to buy)
Any advice would be appreciated!
Thanks, Jim
I’m building Pass ACA mono blocks to mate w/ some of the single full range driver speakers I have built, so I need a pre. I use a passive pre w/ the Dynakitparts ST-35 I built a few tears ago, but the input impedance of the ACA seems too low for this approach.
I’m not a hard-core electronics guy like most of you, nor do I have lots of cash for this project. So I want to do something quick dirty to get up & running. There are some folks on another site who seem to like the SainSmart 6N3, so I ordered one. (see: http://www.amazon.com/SainSmart-Ass...qid=1463360213&sr=8-1&keywords=sain+smart+6n3 ) I also picked up some NOS GE JAN 5670w tubes to use in place of the stock Chinese tubes.
My concern is that the transformer is labeled as 110 v. input. My wall sockets measure 124 v. (most of the time). Output from the transformer measures correspondingly more than the 6.3 v. for the heaters and 170 v. for the plates.
What to do?
1) Use it ‘as is’ & burn through tubes?
2) buy a new transformer? buy a step down transformer? (but I have no clue what to buy)
Any advice would be appreciated!
Thanks, Jim
ACA with 2.2k resistor mod can output max power of 6W. It has gain of 5x. If your source can put out 2V then you do need just buffer preamp - no voltage gain. For this I recommend B1 buffer.
If you really need preamp with voltage gain and want tubes, look at aikido preamp. You can vary its gain by changing input tube type.
If you really need preamp with voltage gain and want tubes, look at aikido preamp. You can vary its gain by changing input tube type.
Kacernator.
While the B1 would no doubt be far superior, it exceeds both my budget and skill set.
The Question remains: change transformer or add step down?
Cheers, Jim
While the B1 would no doubt be far superior, it exceeds both my budget and skill set.
The Question remains: change transformer or add step down?
Cheers, Jim
Put 1Ω 2W resistor in series with the 6.3V connection.That will give you a drop of 0.7V.If the 170V is become 185V or so that's no problem.
Mona
Mona
Mona,
Thank You! Thank You! Thank You!
That is the information I need! And so simple too. As a speaker builder, it just so happens that I have 1Ω resistors (10 watt Mills actually) in the parts bin for baffle step correction and cross-overs.
Much Appreciated,
Jim
Thank You! Thank You! Thank You!
That is the information I need! And so simple too. As a speaker builder, it just so happens that I have 1Ω resistors (10 watt Mills actually) in the parts bin for baffle step correction and cross-overs.
Much Appreciated,
Jim
I built a B1 quick'n'dirty without matching the transistors and simply on a hole grid board / hole raster board. It is easy to do and not expensive. A nice project for a rainy day on the weekend 😉
2 Reasons:
1. The pot that comes fitted is in the output circuit; it is better to have it on the input.
2. The standard pot has been reported two have an imbalance between L & R; The Alps pot is of a higher quality, and does not have this imbalance.
The beauty of this device is that it works well out of the box, but each subsequent modification has a noticeable, if not quantifiable, improvement.
Lots of information here: "Say Hello! to my new little friend" | Audiokarma Home Audio Stereo Discussion Forums
"works well out of the box" and Audiophile Bargain
Just the bargain part:
-Many report mainstransformer getting really hot, some report transformer failing after powering up just a couple of times.
-Some (freaky) measure the voltage over the 200V electrolytics and find voltages above 200V
-Some actually tell you the heater +voltage is connected to audioground
Audiophiles couldn't care less and start replacing coupling capacitors to improve the amp 😀
Just the bargain part:
-Many report mainstransformer getting really hot, some report transformer failing after powering up just a couple of times.
-Some (freaky) measure the voltage over the 200V electrolytics and find voltages above 200V
-Some actually tell you the heater +voltage is connected to audioground
Audiophiles couldn't care less and start replacing coupling capacitors to improve the amp 😀
Hi everyone ! I will get one quite soon
on the basis of some very good reviews i am now quite curious ... and the 30USD price has made the rest
anyone who has performed any of the suggested modifications above ?
In particular is not the pot at the output a very strange solution ? i think that the common choice is a pot at the input
and open. I understand some of the resistors are smd ... that complicates things a lot.
I intend to use just the 1st tube as a buffer not needing any voltage gain. 🙄
on the basis of some very good reviews i am now quite curious ... and the 30USD price has made the rest
anyone who has performed any of the suggested modifications above ?
In particular is not the pot at the output a very strange solution ? i think that the common choice is a pot at the input
and open. I understand some of the resistors are smd ... that complicates things a lot.
I intend to use just the 1st tube as a buffer not needing any voltage gain. 🙄
Clear concise and correct answer. Hats off ! And congrats to your
Vivaldi Government!
Thank you, but not so shure anymore.Someone wrote that voltages where measured over 200V with electrlytics rating only 200V.If thru things get worse with higher voltage 😱
Mona
Hi i will get one in the next weeks. I wil take pics and measure voltages with protective gloves. I do not like what other people already disliked ... like the pot at the output. Just tell me how many preamps are done like that ... almost no one. There must be a reason. I intend to take the signal out of the cathode of the 1st tube and use the unit only as a buffer. I just need some tube flavour to my solid state chain. Just that.
Nobody who has it ?
Anyway ... when i saw those smd resistors ... i wanted to cry Why smd i do not understand It is not a dac ... just make the board twice as big and use conventional sized parts
Weird decision indeed
Nobody who has it ?
Anyway ... when i saw those smd resistors ... i wanted to cry Why smd i do not understand It is not a dac ... just make the board twice as big and use conventional sized parts
Weird decision indeed
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Hi just to ask a question.
If i will take the signal out directly from the cathode pins on the 1st tube will it act as a buffer ?
i intend to insert and use only the 1st tube and take out everything else I will leave it even without volume control. Just a plain buffer as i not need voltage gain at all.
I guess i will have to add just two output 4uF caps soldered on the cathode pins of the 1st tube to block DC on one side and going to the output RCAs on the other side. I do I just need a buffer able to drive 10k Zin power amps.
In this way i would avoid some issues found with the original design.
I also intend to use long pins tube sockets to make things easier
Thanks a lot
If i will take the signal out directly from the cathode pins on the 1st tube will it act as a buffer ?
i intend to insert and use only the 1st tube and take out everything else I will leave it even without volume control. Just a plain buffer as i not need voltage gain at all.
I guess i will have to add just two output 4uF caps soldered on the cathode pins of the 1st tube to block DC on one side and going to the output RCAs on the other side. I do I just need a buffer able to drive 10k Zin power amps.
In this way i would avoid some issues found with the original design.
I also intend to use long pins tube sockets to make things easier
Thanks a lot
Attachments
Don't make the cap too big, this will increase leakage and most important
it might create nasty on / off transients.
Depending on your speakers 0.68 to 1 uF might be more appropiate.
Hi ! thanks a lot for the very kind and valuable advice. So any tube in a decent design could work as a buffere if i take the signal out of its cathode ? i am not an expert and this i need to be sure of.
Then i would like to find some tube sockets with longer pins ... that could help with in-air wiring ... to solder parts to the pin i mean. I am quite excited by this project.
I like what one tubes can provide in a all solid state chain. I was thinking also to a dac with tubes at the output as an alternative. Different approach. But just one tube on the signal path can do wonder to the sound.
I am sure of this.
Thanks again and kind regards, gino
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