let's talk about tubes for Quickie
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4krow
Guest
While these tubes seem to be microphonic by nature, I have found that Telefunken tubes have a bit less of the problem. I have only tried the originals and the Tel's so there may be other observations out there. I use Herbies dampers on the tubes as well.
denti alligator
New member
which of the Herbies dampers do you use?
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4krow
Guest
I don't recall the model, but I went for the one that cost $13 ea. After reading through the website, I found that this damper had all of the benefits of their top of the line at that time, and was cheaper. The difference that I notice is small, but to be fair, I haven't listened very much yet, as the Quickie is getting remade. I am working on it today.
denti alligator
New member
one of the these, I assume:
http://herbiesaudiolab.net/preamp.htm
what's the size of the Quickie tubes? 5/8" to 3/4"?
http://herbiesaudiolab.net/preamp.htm
what's the size of the Quickie tubes? 5/8" to 3/4"?
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4krow
Guest
You are correct sir.
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4krow
Guest
One thing that I would like to mention about the Telefunkin tubes, is that near full volume, they have a lot of distortion. To be fair, I rather think that it might have to do with something else that I have done with the circuit. So far, I have changed the original volume control to a stepped attenuator, but I'm thinking that's not it. I have changed out output caps twice, and the problem has occurred with both caps. Other than those two things nothing much has been done. That is why I tend to think that these tubes might be the reason. Ok, now I have to switch back to the originals just to check.
You might measure the plate voltages with the Telefunken tubes installed, they might be a little higher than desired (which could cause earlier clipping).
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4krow
Guest
Would this even occur if voltages and resistances checked out?
4krow said:
Distortion at high volumes (gain) I have not noticed before. I even took the volume control out and didn't notice any real change in distortion. In the end the pot sounded better than the digital volume control. Not sure why the tube is getting overdriven like that.
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4krow
Guest
Just a shot here. Would heater voltage have any effect?
Paul Joppa
Moderator
The Quickie has fairly limited output voltage capability. Into a high impedance load, clipping would be expected at 3.5vRMS with fresh batteries, 2.3vRMS at the end of battery life. For myself, I'd prefer to keep it below 1.0 volts to avoid audible coloration - but it depends a lot of what the meaning of "audible" is! For comparison, BeePre or Foreplay should put out 20vRMS before clipping.
If your amp/speaker combination needs more that 1vRMS peaks, Quickie can run into trouble.
If your amp/speaker combination needs more that 1vRMS peaks, Quickie can run into trouble.
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4krow
Guest
I will look into this tomm.
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4krow
Guest
Let's work it backward from the speakers, no numbers as such just logic. The more sensitive the speakers, the less they will need from the amp. The less that the amp is required to give out in power to a speaker, the less the input signal needs to be. If the Quickie falls into that premise, then it is fine with giving it's lower output. I'm not learned enough to get into figures here, but that would be my logic.
Paul Joppa said:
Now this is getting interesting because I'm square in the middle of fussing with my PJCCS. From what Paul is saying it would be good to play with the current on the PJCCS by, say, lowering the 4.2K resistor to 3.3K or so, like was suggested. I'm considering this on my mod. I havent tried it yet. It could be a solution to the "overdrive" issue.
One other thing, since its on the topic here... I JUST did some "tube rolling" with the Q. Now that I have the PJCCS in, I thought I would give it a quick run. No big woop-de-doo double blind with electrodes attached to my brain or anything mind you. So here it is:
1. Mullards - nice mids right away. Kind of enticing. Less bass punch than the Teles, notice that right away as well. A nice euphonic vibe though all together. After some listening I got sick of them. I think part of the problem is that one of the tubes, or both may have high hours. Thats my impression. I get some of that crackle that I get with tubes about ready to go. So, may not be a representative sample.
2. RCA - Off the bat I like those even more. Lots of sound, was the impression. Got sick of it pretty quick though. Just not super good "definition" IMO. Nothing wrong. Its just that I've been listening to my Tele's for months now. I would say that compared to the Mullards they are more flat in frequency response, in a good way. Possibly a bit "quicker" than the Mullards as well. The Mullards were just too fatiguing. Again, they may be worn out.
3. Telefunken - Now thats it. Got them back in, and I got my Q back. It just sounds more like music instead of listening to some bunch of electronics. Its just right. Again - no double blind here. Highly biased. But the other thing is, when I make a change I am looking for a good "change" whatever that may be. Sometimes you want something new. I was hoping for something new to listen to. No such luck, or...
cheers - Eric
1. Mullards - nice mids right away. Kind of enticing. Less bass punch than the Teles, notice that right away as well. A nice euphonic vibe though all together. After some listening I got sick of them. I think part of the problem is that one of the tubes, or both may have high hours. Thats my impression. I get some of that crackle that I get with tubes about ready to go. So, may not be a representative sample.
2. RCA - Off the bat I like those even more. Lots of sound, was the impression. Got sick of it pretty quick though. Just not super good "definition" IMO. Nothing wrong. Its just that I've been listening to my Tele's for months now. I would say that compared to the Mullards they are more flat in frequency response, in a good way. Possibly a bit "quicker" than the Mullards as well. The Mullards were just too fatiguing. Again, they may be worn out.
3. Telefunken - Now thats it. Got them back in, and I got my Q back. It just sounds more like music instead of listening to some bunch of electronics. Its just right. Again - no double blind here. Highly biased. But the other thing is, when I make a change I am looking for a good "change" whatever that may be. Sometimes you want something new. I was hoping for something new to listen to. No such luck, or...
cheers - Eric
Paul Joppa
Moderator
Your logic is good - live long and prosper!4krow said:
Some details are in my paper of Signals and Noise (off the Community page) if you want to do the calculations. Or, if I don't get too many requests, I'll do it - what is the speaker sensitivity (or efficiency) and the amp's gain (or max power + input voltage for max power)?
