RCA Outputs for Impasse ?
Hello Everyone : Im very interested in building this preamp ! Being on a limited budget things take alot longer as I have to save for each project ect... I am currently building a F4 and it may be some time before I can construct another. My question is can the Impasse be constructed using rca's for an output ? This will allow me to listen while saving to build another ect...
Hello Everyone : Im very interested in building this preamp ! Being on a limited budget things take alot longer as I have to save for each project ect... I am currently building a F4 and it may be some time before I can construct another. My question is can the Impasse be constructed using rca's for an output ? This will allow me to listen while saving to build another ect...
If you want to use it as a single-ended out preamp (albeit with rather high gain!), you can do that by grounding the cap that comes from the plate of the ECC88, then taking the output from the cap that comes from the cathode of the ECC88. It works very well that way.
SY, Thank-you for the quick reply ! As for the gain, would it be to high for my intended use ? Will a single F4 amp have a problem when using the Impasse as described with SE outputs ? 😕 I have an old Cary AE-3 preamp with a gain of 20 that I had thought to use. It uses 2 > 6SN7's in a SE Class-A style ! It sounds very good but also has its limits ect...
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The gain will be similar to the Cary. In my system, that's too high (my sources don't need more than unity). If the Cary was OK in yours as far as gain is concerned, then the ImPasse should work fine for you.
SY, Again thank's this is the preamp I speak of > http://www.audioxpress.com/reviews/media/GA400HA2.pdf Mine is a newer version with a improved Psu ect... I have not as of yet completed my F4 meanwhile I currently use an older Denon amp with the AE-3 and a Sony DVD player for source ect...
Impasse rebuild
OK ,
I have an issue at power up with the right channel whistling for a few seconds and then working fine. Also I was a little rushed during the initial build and in re-soldering some connections I burnt a few of the pads on my board. So I ordered a new board from Jack and will perform a overhaul.The board I have is not correctly routed for the Jenson transformers, I was wandering if the replacement board will have the same issue?
Bill
OK ,
I have an issue at power up with the right channel whistling for a few seconds and then working fine. Also I was a little rushed during the initial build and in re-soldering some connections I burnt a few of the pads on my board. So I ordered a new board from Jack and will perform a overhaul.The board I have is not correctly routed for the Jenson transformers, I was wandering if the replacement board will have the same issue?
Bill
I am finally getting around to finishing my PSU, man it's been too long.
I have one question though. I plan on using two separate heater windings, one for each tube. These windings don't have a center tap, so I was planning on making on for each heater out of a pair of 100 resistors. My question is, can I then tie both of these center taps together and then connect that to my voltage divider to elevate the heaters, or do I need two voltage dividers, one for each heater.
Seems like a single reference is okay, but I didn't know if there was something else at play that I wasn't thinking about. Here's hoping that I can knock this out over the holiday!
I have one question though. I plan on using two separate heater windings, one for each tube. These windings don't have a center tap, so I was planning on making on for each heater out of a pair of 100 resistors. My question is, can I then tie both of these center taps together and then connect that to my voltage divider to elevate the heaters, or do I need two voltage dividers, one for each heater.
Seems like a single reference is okay, but I didn't know if there was something else at play that I wasn't thinking about. Here's hoping that I can knock this out over the holiday!
excellent!
I have one more unrelated question. When people typically measure a balanced output preamp such as this, for say distortion, or just hooking a scope up to the output to make sure it's functioning, do people typically people measure across the balanced output, ignoring the ground?
I noticed you can buy an unwired version of this:
Neutrik - Audio - Circular Adapters - NA2MBNC
I was thinking about picking one up and wiring the positive output to the pin, and the negative output to the shell. Then I could plug that into my scope, or if I can ever figure out how to use my HP distortion analyzer, etc. In fact, in this case of using the HP, I could put another one on the input, and the transformer should take care of unbalanced to balanced conversion and I should be able to measure end-to-end.
The default wiring of these is 2 hot, and 1 and 3 to ground, that's why I'd pick up the unwired version.
Are my assumptions somewhat sane?
I have one more unrelated question. When people typically measure a balanced output preamp such as this, for say distortion, or just hooking a scope up to the output to make sure it's functioning, do people typically people measure across the balanced output, ignoring the ground?
I noticed you can buy an unwired version of this:
Neutrik - Audio - Circular Adapters - NA2MBNC
I was thinking about picking one up and wiring the positive output to the pin, and the negative output to the shell. Then I could plug that into my scope, or if I can ever figure out how to use my HP distortion analyzer, etc. In fact, in this case of using the HP, I could put another one on the input, and the transformer should take care of unbalanced to balanced conversion and I should be able to measure end-to-end.
The default wiring of these is 2 hot, and 1 and 3 to ground, that's why I'd pick up the unwired version.
Are my assumptions somewhat sane?
I use a dual trace scope and stick a probe on each leg of the output. For distortion, I used a balanced input soundcard.
Each time I see a ref to Pin 1, I point out the following reference:
Pin 1 Revisited
Pin 1 Revisited
g,day all
first let me say thankyou to all for making this pre availiable to diy,ers (especially jakinnj i have built some great amps thanks to your store)
i have just bought the assembled impasse kit on youre site and am wondering if i also need to purchase the power supply kit as well ?
i will be using it to drive 2x f4 in mono balanced configuration
regards sheafer
first let me say thankyou to all for making this pre availiable to diy,ers (especially jakinnj i have built some great amps thanks to your store)
i have just bought the assembled impasse kit on youre site and am wondering if i also need to purchase the power supply kit as well ?
i will be using it to drive 2x f4 in mono balanced configuration
regards sheafer
jeez i hope i have done the right thing choosing this pre
is no one interested in the impasse any more?
is no one interested in the impasse any more?
It was soooo last year. 😀
The power supply isn't enormously critical. I used a very simple regulator and got excellent results.
The power supply isn't enormously critical. I used a very simple regulator and got excellent results.
Unfortunately, owing to the floods here I have been unable to provide the assembled Impasse. I've got other stuff going on which necessitates a lot of travel for the next several months, so (while you will see me on DIYAUDIO) I am only going to sell the boards at my cost. I also have some Cinemag 10K:10K which I will dispense at cost.
That being said, I reworked the boards to amend the error I'd made with the Depletion MOSFETs and straightened out the layout a bit. The results are pretty good. In single ended mode with 10K load the THD% with 2.828V out is 0.0037%. (SY said in the article: "better than 0.01%). I found that Electro-Harmonix worked best, but YMMV. I also substituted 1u/400V on the output as I used the rest of my 0.47u/400V on another project.
That being said, I reworked the boards to amend the error I'd made with the Depletion MOSFETs and straightened out the layout a bit. The results are pretty good. In single ended mode with 10K load the THD% with 2.828V out is 0.0037%. (SY said in the article: "better than 0.01%). I found that Electro-Harmonix worked best, but YMMV. I also substituted 1u/400V on the output as I used the rest of my 0.47u/400V on another project.
An externally hosted image should be here but it was not working when we last tested it.
I was able to simultaneously analyze each channel. One was run balanced, the other single-ended, 1kHz in, level adjusted for 2.83V out:
This is far from an ideal test setup -- the boards are just sitting on the workbench without benefit of chassis, etc. Pretty darned good, I would say.
An externally hosted image should be here but it was not working when we last tested it.
This is far from an ideal test setup -- the boards are just sitting on the workbench without benefit of chassis, etc. Pretty darned good, I would say.
