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Old 26th February 2021, 01:45 AM   #21
FlaCharlie is offline FlaCharlie  United States
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Quote:
Originally Posted by Flaxxer View Post
I know what a stepped attenuator is, but what is a quad audio taper pot ? Is this just another type of attenuator? So please let me ask for simplicity's sake. The way you are suggesting me run this, is my DAC wide open on its volume. Then use and attenuator all the way down to zero for no sound, and simply turn it up for my master volume. Is this correct?

And when you mention four source/cathode followers, are these something that adds tubes for the warmth and tube rolling I wanted to try? Or something else? Thanks for your patience.

I appreciate you letting me in on the specs of the D90 on the balanced outputs. I will definitely be going balanced. Someone sent me a link for a Gold Point stepped attenuator, but it was almost $600. I buy a preamp first. So so let me ask, there are a million stepped attenuator at every price point on the net. Do you know if any reasonably priced, say no more than $300 attenuators which will not hurt my sound quality and are balanced? Ready to purchase, and this is why I'm asking such Direct questions. Thank you so much for the help.
As you can see, the discussion gets pretty technical on this forum. As you would expect, most people who post here build things themselves and they're not accustomed to making suggestions to people who have no understanding of electronics. I'm into tubes but my technical knowledge is limited and I have no knowledge whatsoever about solid state stuff like MOSFETs.

I'm sure that, ideally, you would like to find a commercially available device(s) that are just plug and play.

If you just want to use the regular, non-balanced, inputs and outputs in your gear it sounds like you will need some gain. For a cheap way to get it you might want to investigate this thread.

FX Audio 6j1 tube preamp - a $31 wonder | Audiokarma Home Audio Stereo Discussion Forums

I don't own one of these but I breadboarded the circuit, even using the low, less than optimal, voltages it uses and it sounded OK. Not great but it does add some "tube warmth", which is what most people who buy them are looking for.

Despite being sold as buffers, they are not. They are preamps that have gain. There are several versions and the price is probably a bit higher now but it's a plug and play item that will give you some "tube warmth". They do not, however, have super low output impedance that your amp, ideally, would like to see. But they will work. It seems that most everyone uses them with SS or chip amps, not tube amps. Even though the match is not ideal, it must not be too bad because they have a loyal following. They are definitely not audiophile grade or state of the art.

One way to solve the impedance match issue would be to use a cathode follower tube buffer. It will not have gain but it will make it easier to drive your amp. Here's a super cheap buffer kit with everything you need including the tube.

Diy 6N3 Tube Buffer Bile Pre-amplifier Board For Filtering Amplifier Audio | eBay

I've never used a buffer and know nothing about the details of their design. But this is cheap enough, for sure.

If you need gain and a better impedance match, I suppose you could put this between the FX preamp and your amp and you'd have both for a total cost of well under $100.

There may be other solutions that are better, I don't know. But there is absolutely no need to spend big $$$ on solutions to your problem. IMO, the preamp you linked is incredibly overpriced. The parts it uses would cost well under $100. It could even be built without using a circuit board, wired point to point using the same parts on a breadboard, which is just a slab of wood.

Volume controls use an audio taper not a linear taper. I'll leave it to you to look up the difference. The "quad" part just means it's a four section pot. I believe it need four because he was suggesting using a balanced connection. An unbalanced stereo connection just uses two.

Stepped attenuators are just volume controls that use a combination of resistors to attenuate (reduce) the signal level. They go up in price if they use exotic resistors and as the number of steps increases.

I use this one in a preamp I built and it sounds fine.

DACT Type 21 Stepped Attenuator Potentiometer 100K for Amp/Preamp, 2A3, 300B... | eBay

My only complaint was that I sometimes would like a finer adjustment - one step was just a bit too quiet and the next was just a bit too loud. This may or may not be an issue for you. I solved it by using a pair of conventional (not stepped) mono volume pots on the input. This allows me to change the right/left balance. I use the stepped attenuator on the output to set the overall volume. This is exactly the setup that Decware claims that their preamp uses but, as I pointed out, the second pot to control the output gain is nowhere to be seen in the pic on their site.
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Old 26th February 2021, 03:57 AM   #22
Flaxxer is offline Flaxxer  United States
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I am just fine with soldering kits together either PC board or direct wire to wire. I just have no clue what I'm doing designing or what I'm looking at. I can read where stuff goes and solder at their though. I don't mind kits if they're as good as what commercially available. The thing is, the D90 Dak I'm going to use puts out a full 4 volts, which will drive my amplifiers to full volume. I just need to attenuate the sound downwards to zero, and back up to whatever volume I need.. I just need to know the best way to do that for a reasonable price. I don't mind spending a few hundred dollars, but don't want more than what I need.
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Old 26th February 2021, 05:14 AM   #23
kodabmx is online now kodabmx  Canada
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Building an all tube gain stage ...
My line/headphone amp board/kit might be of interest. There are three versions for use with different tube types, and it's very affordable, especially if you don't need to drive headphones (big caps cost money).

Here's a thread about it: 6N3/6N6 headphone amp using PCB.
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Old 26th February 2021, 06:20 AM   #24
Chris Hornbeck is offline Chris Hornbeck  United States
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Quote:
Originally Posted by Flaxxer View Post
The thing is, the D90 Dak I'm going to use puts out a full 4 volts, which will drive my amplifiers to full volume. I just need to attenuate the sound downwards to zero, and back up to whatever volume I need.

At this point a lot of folks here are biting their lips to stay quiet, rather than possibly offend. What they don't want to say is that this sales pitch is extra virgin snake oil, and that you don't need anything. The concept of a distortion generator "improving" your sound is specious at best. You have enough drive (although you've never actually said) and you have a volume control (as I interpret it). Done.



YOS,
Chris
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Old 26th February 2021, 07:38 AM   #25
jean-paul is offline jean-paul  Netherlands
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Bravo, Chris! It is a very persistent bad habit to want to add superfluous gain and extra noise only to then spend a lot of time fixing issues. The logic behind it is often nil.

In this case 4V rms for full output adding a black box in between that has gain (why? To have 16V rms?) and likely has higher output impedance and less drive than the source connected to it ... Really?

Yesterday I dealt with a similar case. Someone wanted to add a manually operated preamplifier to a perfectly fine integrated (expensive) amplifier that already has source selection, volume control and even remote control. When I asked why I did not get an answer but I was looked at as if I was not 100%. "I read on the internet that...." Maybe it is because of Covid that people want to "do something".
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Last edited by jean-paul; 26th February 2021 at 07:54 AM.
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Old 26th February 2021, 03:51 PM   #26
FlaCharlie is offline FlaCharlie  United States
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Quote:
Originally Posted by Flaxxer View Post
I am just fine with soldering kits together either PC board or direct wire to wire. I just have no clue what I'm doing designing or what I'm looking at. I can read where stuff goes and solder at their though. I don't mind kits if they're as good as what commercially available. The thing is, the D90 Dak I'm going to use puts out a full 4 volts, which will drive my amplifiers to full volume. I just need to attenuate the sound downwards to zero, and back up to whatever volume I need.. I just need to know the best way to do that for a reasonable price. I don't mind spending a few hundred dollars, but don't want more than what I need.
If you've determined that you don't actually need any gain, Chris and jean-paul are correct. Just add a volume pot or stepped attenuator and you're done.

No need to spend big bucks. Try the cheap one I linked.

I've never used balanced inputs and the suggestion was to use a quad volume control with them. If that's what they require then just buy two of the ones I linked - one for each channel. This would also function as a balance control. The seller has listings for pairs and also has different values. I've always just used 100k but other values may be better. Perhaps someone will comment.

The reason I linked the thread about the cheap FX-01 preamp is because you said you wanted some "tube warmth" which is, of course, adding some distortion. If people find this distortion pleasant, they call it "warmth". If they find it bothersome or if they're purists who always pursue the lowest possible distortion measurements, they just call it distortion.

Any additional tube stage will add some distortion, even a very well designed one. The FX is definitely a non-optimal design, which I've pointed out repeatedly on the FX thread. But it's cheap to try if you really do want to hear what your amp sounds like with some additional "warmth".

Many people who use SS or chip amps find them to be a bit (pick your adjective) cold, dry, harsh, clinical . . . whatever. I prefer tube amps myself. I do actually own a few amps that use the ICE power module but they are instrument amps (bass guitar). I don't know how they sound in a stereo reproduction role.

Both the FX and the Decware do add gain, which it sounds like you would need if you use normal RCAs instead of balanced connections.

If you're not concerned about adding some "tube warmth", just use the balanced outputs (which others say have enough gain), add a simple stepped attenuator and you're done.

Either way, I would strongly suggest that you start with a basic, inexpensive, solution. If, for some reason, you find it lacking, you're not out a lot of money. You can always upgrade it to an official audiophool approved high dollar version later.

Last edited by FlaCharlie; 26th February 2021 at 03:57 PM.
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Old 26th February 2021, 05:30 PM   #27
astouffer is offline astouffer  United States
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The company has a 6 month wait time because they probably collect orders until they have enough money for a manufacturing run. Any tube line stage with a bit of gain will get you where you need to be.
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Old 26th February 2021, 05:56 PM   #28
TG is online now TG  Ukraine
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Quote:
Originally Posted by FlaCharlie View Post
I've never used balanced inputs and the suggestion was to use a quad volume control with them. If that's what they require then just buy two of the ones I linked - one for each channel. This would also function as a balance control. The seller has listings for pairs and also has different values. I've always just used 100k but other values may be better. Perhaps someone will comment.
ASP1000's input impedance is only 8kOhm, so 100k pot alone won't work here. In fact, the pot of any value won't. Some kind of buffer (gain of 1, high input/low output impedance) is needed - that's why I've suggested using cathode/source followers.
"Usual" (= designed to work with "infinite" load) stepped attenuators won't work without a buffer either.

Constant impedance attenuators like this will work fine if you recalculate the resistors' value to match the 8k input impedance (basically decrease all of the values by 20%) and put it close to the power modules. And no, I don't know if it can be purchased as a kit or readily-built device.
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