Bottlehead Forum
Bottlehead Kits => Legacy Kit Products => Quickie => Topic started by: charger on August 04, 2013, 06:25:09 AM
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which brand of tubes are better for the Quickie ? which are less microphonic ?
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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.
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which of the Herbies dampers do you use?
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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.
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one of the these, I assume:
http://herbiesaudiolab.net/preamp.htm
what's the size of the Quickie tubes? 5/8" to 3/4"?
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You are correct sir.
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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.
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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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Dont forget about the definitive reference for Q technology:
http://www.bottlehead.com/smf/index.php/topic,3491.0.html
IMOSSMS. ;D
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Would this even occur if voltages and resistances checked out?
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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.
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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Just a shot here. Would heater voltage have any effect?
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Like too much? I use rechargeables so I'm always less than 1.5V. Experts can chime in here, but I dont notice any difference in sound as the heater batteries go low. I usually just hear one channel cut out when the voltage gets too low.
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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.
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I will look into this tomm.
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"If your amp/speaker combination needs more that 1vRMS peaks, Quickie can run into trouble." Pardon my ignorance. But how would I know if this is the case?.. combo needing more than 1v...
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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.
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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.
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.
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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
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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.
Your logic is good - live long and prosper!
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)?
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Thank you Paul. If we can reason from simplicity itself, then starting on the same page is likely. THEN the numbers can roll.
Eric, Maybe that ;s what I like about the Telefunken tubes as well. I just gotta add that I actually bought these tubes still fresh in the box. It was kind of an experience to take off the cellophane wrapper. It had a red stripe that you pull, just like on cigarette packs.
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Mine were fresh in the box as well
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Earic,
This is NOT a competition....but my tubes were both virgin, and innocent.
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Thank you much Dr. Lambert.... So, If I have 85db 8 ohm speakers and a powerful amp, the quickie will play fine or run out of juice quickly? again , sorry for my lack... or basically give me the best case speaker/amp setup for a quickie please...
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Hello Chris,
This depends on the senstivity of your amplifier. It may require 1/4 of a volt to reach full power, or it may require 5 volts to reach full power. (This is specified as input sensitivity, or alternitavely it can be determined from the amplifier's gain as well)
-PB
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Ok, thank you Paul, so can the quickie be used with ANY amp and sound great? or to sound its best, there are certain restrictions that apply that say a BeePre doesnt have due to its 20v capabilities?.. someday, I will be "asking you, haha" to build me a BeePre as a reference preamp, but, when I get to building here, I want to start with a quickie to build myself and use it for my desktop computer system for basically low volume listening with Doc and PJs new el84 kit coming out at a later date :) ..... I already know my speakers will be Kefs LS50s.. They are 85ish db sensitive..So again, the quickie will just be for low volume listening and will be matched with another bottlehead kit that may or may not come out at a later date.. OR I want the quickie to play around with my other solid state amps that I have laying around.. So, in a nutshell, are all these desires that I have , possible with the quickie, or is it just a true system dependent component in order to sound good... It sounds like EVERYONE likes their quickie no matter what components they have, so maybe Mr. Joppa just freaked me out for no reason...haha :)
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Also, when a seller says, used but tested as new... can a tube test as new for hundreds of hours of use and then start dropping off, when it is starting to go down "the tubes", or is it a steady gradual decline that can be picked up by the tester?
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Chris, From what I can tell, many, if not most of the BH group tend to have high sensitivity speakers( much higher than 85db, as you stated). It's still a juggle of things beyond that, but if the system is in sync, as far as sensitivity, size of room, type of music, etc. then the Quickie does quite well. An amplifier that can run on a lower voltage(input sensitivity), would be a better choice in your case. Not to mention adequate power and gain. 85db sensitivity for speakers is low in my book, and is a part of the whole chain of things spoken about in previous posts here.
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Also, when a seller says, used but tested as new... can a tube test as new for hundreds of hours of use and then start dropping off, when it is starting to go down "the tubes", or is it a steady gradual decline that can be picked up by the tester?
Yeah, a tube can test "as new" for 10,000+ hours (I have a few 6SN7's that exhibit this behavior). Regardless of this, emission dropoff is generally extremely gradual.
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Thank you 4k.. Yeah, I know 85db is low, but they sounded SUPERB with a cayin 300b amp I heard them with, And since they will be nearfield, I think they should be Ok.. In a nutshell, I want to get the quickie anyway, no matter what.. Just to have (what a neat little pre) and get building experience.. So, in the end it doesnt really matter so much I guess because when ready (moved), I will look into amp matching with a stereomour or something else that Dr. Frankenjoppa's genius can cook up in his lab, and just have a quickie for doing what you guys do.. tweaking and playing around with it... After all, as we know, the price of admission for entrance into the quickieland play experience is the best in audio!! So, thank you all for the answers. Sorry? What was that Doc? "just build the damn thing and plug it into all my amps and find out??" Yep, you are right, I will do just that.... Not sure you have to swear though.... :) Sorry guys, If I am weirder than normal, I have not slept for 34 hours, so forgive me...
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So, buying a "tested as new" tube is a gamble then? Do you stay away from tubes like that? or I am sure as usual, it all depends on the asking price etc..ok, so when a tube starts its gradual decline, can there still be thousands of hours of life and good sound left depending on the tube? Cuz, i hear tubes like teles can maybe be 100,000 hours.?.. thank you
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I would stay away from any used tube, you have no idea of how many hours are on it. NOS or new old stock, is the way to go, given that the seller is honest.
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Yeah, you are right Sturm.... just opens up for fraud and bad purchase stories...
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I generally opt for used tubes, as very little new old stock is new.
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Kinda like buying a used car, eh? Once again, I refer to Vintage Tube Service. And yes, I'm sure that there are others. I typically go for new tubes, but when I deal with Andy at VTL, I don't wonder so much. And then there is the group of sellers who THINK they know what they are talking about. It's a tough call for me at least.
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Yeah, a trusted service is probably the best way to go.. and Yeah, PB, makes sense, most NOS tubes may not be new anyway... I will just avoid ebay...
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There's no reason to avoid eBay, it's easy enough to make returns. It's also worth mentioning that a tube like the 3S4 will almost always be NOS, as used old stock of inexpensive tubes like these will generally be discarded as used pulls.
Looking on eBay, all but one or two of the listings are almost certainly new old stock.
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I would second that in terms of the cheaper tubes. There is no profit in selling totally used 3s4's. They are cheap to begin with! Those that have them, they are probably going to be NOS. For $5 its worth a shot!
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OFF TOPIC
does Q , as the batteries lows down , needs to rise the volume pot ?
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The gain should not change much with low battery operation, until the filament voltage gets too low to maintain emission. Usually this will be around 1.0 volt.