Bottlehead Forum
Bottlehead Kits => Legacy Kit Products => Quickie => Topic started by: Bonzo on July 10, 2013, 08:23:05 AM
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Good evening to all.
I hope not to break any forum's rule or behave, but as I need 3 inputs I rebuilt a Quickie drilling my own plexyglass plate!
I use new cat5 wire, and I change output capacitors too (first with a pair of MGBO I wasn't satisfied of, then I use a pair of K75, much better!).
I love the sound of Quickie, in my opinion it's more musical than Pass B1 I also build.
Thank you for this awesome kit, it s really important to allow everyone to experiment the wonderful sound of DH tubes.
Ciao!
_edit: now she has a name ;-) _
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"The Bonze"- it could work ...it could. Anyway, I have considered drilling a brass plate for a Quickie. I like the the looks of brass, and who knows, it might serve as shielding in some regard.
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Brass would look nice! Lots of good ideas out there.
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;D
So she's christened "the Bonze".
I'm really happy with her, I'm enjoying some music as I'm typing.
Speaking about shelding I'm thinking about trying a plate made by a sandwich of alluminium/plexyglass/alluminium.
I spotted a seller on ebay who sells sheets of this material and I ordered 3 diffferent ones.
They look really good, I bought both brushed and painted ones.
Worth trying, IMO.
Ciao!
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That sounds like a very good idea, using you imagination that is.
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Ok, meester Bonzo, I looked on fleabay and didn't the plates that you are talking about using. Give me a guess as to where I might them.
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I looked on fleabay and didn't the plates that you are talking about using. Give me a guess as to where I might them.
Greg, you seriously need to get back on your anti-seizure meds...
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Ok, meester Bonzo, I looked on fleabay and didn't the plates that you are talking about using. Give me a guess as to where I might them.
Here it is Greg (no affiliation with the seller, if I break any rules please feel free to remove this post).
http://www.ebay.co.uk/itm/170977603830?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649 (http://www.ebay.co.uk/itm/170977603830?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649)
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Greg, you seriously need to get back on your anti-seizure meds...
;D
When I started the rebuilt I spent more than
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JBL l65 Jubal. If these are the speakers that I remember from waaaay back, they were the first great speakers that I ever seen. The ones I remember were floorstanders with a slanted front and that awesome tweeter that didn't look like a speaker at all. Do you have a photo of yours?
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JBL l65 Jubal. If these are the speakers that I remember from waaaay back, they were the first great speakers that I ever seen. The ones I remember were floorstanders with a slanted front and that awesome tweeter that didn't look like a speaker at all. Do you have a photo of yours?
Yessir...both clothed and nude ;)
Mine are the "professional version": en3 enclosure (big 80 liters), but the same loudspeakers and the awesome 077 tweeter.
It was sold in Italy as a kit.
A nice buy for only 150 Euros (only the cost of foam replacement!)
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Bonzo, I have thought it over, and I think that we should trade Quickies. Yah, that would be nice. I'm still working on mine when I get a chance. Volume problem after inserting the new volume control.
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;D ;D
Do you mean a Bottlehead franchising?! It would be nice, if Paul Joppa agree ;D
Or do you mean to arrange a meeting to listen to our Qs? It would be nice too!!
This w-end I invited a good friend at home: he confirmed Q is better than Pass's B1. We listened to a lot of music, from classical to jazz to good progressive rock... everything was very warm end involving, nice!
Now I'm hinking to put those 150h chokes in use... I'll keep tou posted!
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AHA! Yes, the chokes. I did them and overall, I like them. Just another thing that I wish that I could switch back and forth,-from the chokes to the PJJS, both have their rights in circuit at different times.
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The Bonze update!
New chassis done by my best friend,
(https://lh4.googleusercontent.com/-PXZncARALts/U10jeHaYR1I/AAAAAAAAA-I/9dGLMd7ON_0/w240-h320-no/IMG_0087.jpg)
new feet (Mapleshade-inspired),
(https://lh4.googleusercontent.com/-BB9SpUpJpCQ/U10jeWJRqjI/AAAAAAAAA-g/0bt84j6Dr7E/w320-h240-no/IMG_0092.jpg)
choke, stepped attenuator and PIO output caps,
(https://lh5.googleusercontent.com/-sT-PmEYAKHQ/U10jcDMZUxI/AAAAAAAAA9s/N3LfBYdyWNg/w240-h320-no/IMG_0089.jpg)
and some tube rolling ;-)
(https://lh3.googleusercontent.com/-NDwIfI50zfs/U10jdUTcgXI/AAAAAAAAA94/3vSYx9hUOo0/w320-h240-no/IMG_0090.jpg)
(https://lh5.googleusercontent.com/-m1p6Jo-L-Ts/U10jdjt_jYI/AAAAAAAAA-M/tlOSXFotOvE/w240-h320-no/IMG_0091.jpg)
(https://lh5.googleusercontent.com/-up4ZblKO93M/U10jh8_YaoI/AAAAAAAAA-w/qpVlOk1O_5Y/w320-h240-no/IMG_0093.jpg)
(https://lh3.googleusercontent.com/--Ryx9pImycc/U10jfiJRfEI/AAAAAAAAA-s/VMdIwUXmHbc/w240-h320-no/IMG_0094.jpg)
(https://lh4.googleusercontent.com/-hk36Sq1S3R8/U10jgJpWNII/AAAAAAAAA-c/r-PFZMwuF_A/w480-h360-no/IMG_0095.jpg)
(https://lh5.googleusercontent.com/-pM4vNfGfP80/U10jgz8optI/AAAAAAAAA-o/K-4lVEyuQXs/w320-h240-no/IMG_0096.jpg)
Ciao[
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Nice build, curious to your hear your impressions on the various tubes, especially the Philips and Siemens..
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It's hard to describe now, as my system had a lot of canges: new speaker cables (UBYTE), improved psu of my old ecl86 dual mono (now near tube maximum limit, more speed and power).
I based my judge fisrt on microphonic: Philips and Siemens gave me the less microphonic problems of the whole lot, then I hook the Quickie to Darling. The Darling gives a bit of "loudness" effect to the music, so if I don't see this effect I know tubes rolled off something somewhere... So Siemens are a bit bass-shy, but very detailed and "fast", Philips are more balanced but a touch less speed.
The other tubes (RCA, Sylvania, Mullard and RF-not pictured-) are good, RCA non JAN better, but Philips and Siemens are addictive :-)
Always searching for some Telefunken to try them out.
Test disks
3d: any cd from Mapleshade;
Dynamic and speed: any old Dire Straits LP;
Tone test: ELP Picture at an Exhibition LP from Original Master Recording.
Ciao!
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Another update:
I buy a NOS Telefunken pair on ebay Italy...only checked if they work ATM...stay tuned!
Now I think I have all the tubes I need...
Teles are really beautiful, with the old Italian tax stamp on it...lovely!
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Can you post a pic of the tubes with Tax stamps? I have a Marconi tube i got from Italy with unusual labels on it, always wondered what they were.
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Here they are.
The stamp is similar to the ones you can find on vine bottles, I have a pair of lovely Marconi 6sn7 and a pair of 807 with the stamp on it.
Ciao!
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Those labels i have not seen before, interesting. Also interested to hear how you get on with those as you own all of my favorite tubes, the Philips, Siemens, Telefunkens, Navy RCA's, and Mullards.
The Valvos are worth picking up too, and if you mod for 1S4 tubes try a few Czech 1L33's. They are horribly microphonic but i really like em, curious for somebody else to try them and see what they think.
http://bottlehead.com/smf/index.php?topic=6098.0 (http://bottlehead.com/smf/index.php?topic=6098.0)
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fbottlehead.com%2Fsmf%2Findex.php%3Faction%3Ddlattach%3Btopic%3D6098.0%3Battach%3D5586%3Bimage&hash=bc9375ef09c36317adec7edf4909a5c7a46e06e3)
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Ciao mcandmar,
I red your post and always thinking of doing the mod, but I'm too lazy... ;D
I built also a sort of "quickie clone" changing tube's workpoint and something else, just to experiment a bit, maybe i can try the mod on it.
1L33 has also that "glow factor" I miss in the quickie... :)
Speaking about tubes I think standard RCA's are a bit better than JAN ones, the latter being too much microphonic for my taste, now I have to do some more listenig session with the Tele's.
To reduce vibration I use also Mapleshade-inspired cork/rubber feet and I have to admit they do a good job for external vibrations.
I have also considered putting a rubber ring between tube socket and plastic plate.
Ciao!
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You can do the mod via a toggle switch so its a quick and easy changeover. Thats how i have mine setup, and another switch to move a few pins around so i could experiment with 3A4 and 3Q4 tubes too.
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Mcandmar,
Have you noticed any significant differences from trying 3A4s and 3Q4s vs. the 3S4 in sound?
Dave
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Mcandmar,
Have you noticed any significant differences from trying 3A4s and 3Q4s vs. the 3S4 in sound?
Dave
Cant really say as i only bought one set of each to experiment with and never did anything with them. The intention was to work out if any changes to their operating points were needed and modify accordingly. From memory one had higher gain which was useful, one has a higher power output, and there was also differences in trans conductance, distortion specs etc. I wonder if the BH guys have tested them?
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one interesting thing about the 3q4 is that you can get a pair of telefunkens on ebay for $20, vs. $35 for a 3s4 pair!
Dave
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Spotted these recently that interest me, but i'm not paying $40 shipping for them :'(
http://www.ebay.com/itm/Vintage-Radio-TV-Philips-Miniwatt-Tube-Lot-Of-2-DL92-CT323-/181557526859?pt=Vintage_Electronics_R2&hash=item2a45ac014b (http://www.ebay.com/itm/Vintage-Radio-TV-Philips-Miniwatt-Tube-Lot-Of-2-DL92-CT323-/181557526859?pt=Vintage_Electronics_R2&hash=item2a45ac014b)
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Just a thought: 3q4 seems a drop-in replacement to me, according to Radiomuseum.org:
This is our beloved 3s4 http://www.radiomuseum.org/tubes/tube_3s4.html (http://www.radiomuseum.org/tubes/tube_3s4.html)
and this is 3q4 http://www.radiomuseum.org/tubes/tube_3q4.html (http://www.radiomuseum.org/tubes/tube_3q4.html)
They seem pin to pin equal, is it correct?
Instead of a switch, have you tried to build a socket adaptor?
Ciao!
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Yup that looks right, it was the 1S4/3A4 that had different pinouts. You could make adapters, though i dont know what you would start with. I just found it easier and neater to add a few switches, easy to do when your dealing with such small voltages.
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Mcandmar,
today I tried those beasts!
(https://lh4.googleusercontent.com/-ody3CCxtH-k/VPn9aDkFJ5I/AAAAAAAABJc/fTyTYWUw5AA/w926-h520-no/WP_20150306_006.jpg)
3Q5GT so HUGE with the adapter! ::)
(https://lh5.googleusercontent.com/-iXVd6ALrTLE/VPn9f5uDRUI/AAAAAAAABJ0/UMtKJv2xeZw/w292-h520-no/WP_20150306_009.jpg)
Size mismatch ;D
(https://lh6.googleusercontent.com/-KHf8OisID0E/VPn9dIIZFVI/AAAAAAAABJs/TEL3IfHcngM/w292-h520-no/WP_20150306_008.jpg)
Nothing more than a quick check to see if everything works, but they seems pretty good!
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He he. Those look like an interesting tube from a quick scan of the datasheet, were they supposed to be an octal equivalent or the 3Q4?
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Hi Bonzo,
How do you like the sound of the 3Q5GT tube compared to the 3S4?
Dave
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He he. Those look like an interesting tube from a quick scan of the datasheet, were they supposed to be an octal equivalent or the 3Q4?
It seems the equivalent tube is 1C5 (maybe 1C5GT is a bit better ;D ), and they are really cheap on Ebay USA ($8 for a tested quartet!).
Only socket adapter was a bit expensive, but the little quickie is always worth every investment!
I also ordered a pair of 1L33 too, do you think that I can use them in the existing circuit by simply cutting pin n°1? As I told you I'm sooo lazy! ;D ;D
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How do you like the sound of the 3Q5GT tube compared to the 3S4?
Ciao Dave,
ATM I have no time for serious listening test... >:(
From quick listen they seems promising: they are microphonics as usual but not too much, and they sound "correct", more like the Siemens.
The listening the setup was Apple ipod touch with lossless files>direct output from base pins>Quickie>Edcor transformers>AKG 141 (not so optimized... ;D )
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I'll just mention that there are a (small) number of tubes with 2.0v filaments, and that there exist 2-volt sealed lead-acid rechargeable D cells. Type 31 is especially attractive because its gain and plate resistance are close to the 3S4, and it's a real triode.
Finding a charger for the SLA cells will be more of a challenge.
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Thank you Paul...
some more adapter to order (and even some SLA's ;D )
Just to confirm your kit is an endless source of amusement, and your design is simly perfect!
THANK YOU! :)
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2nd that, i have learnt so much about valve amp design from PJ and the quickie, and i'm still not done experimenting. It went from a preamp to a headphone amp, to an AC powered amp, and currently i am waiting for a few caps to finish my latest revision with a high voltage regulated power supply. Still sounds great too!
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Some updates: those big tubes are incredibly microphonic!!
I start suspecting that 3s4 is another design choice is better not to alter... ::)
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lol. The funny thing with the Quickie is that it sounds really good with the pjccs (and there's probably no reason to mod it) but it is so tempting it's hard not to (plus the sound just gets better!)
Dave
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People - the Quickie deliberately follows in the footsteps of the original Foreplay, in being as much for fun and playing with as it is for listening to - it's just a fortunate side benefit that it actually sounds good. Rock on!
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Installed Clarity cap's MR series resistors in the Quickie and niiiiiiiiiiice, fantastic mod. Took the hit out of Bonamassa's voice, added some depth of field for lack of a better term. Really lay's down those goosebumps.
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People - the Quickie deliberately follows in the footsteps of the original Foreplay, in being as much for fun and playing with as it is for listening to - it's just a fortunate side benefit that it actually sounds good. Rock on!
Definitely agree Paul, I couldn't think about changing the Quickie to something else (though i'm sure the other bottlehead pres are a step up!). I'm temped to play with it some times more than others (though there's probably not much more that could be modded-already changed the coupling caps to Russian PIOs and bypass caps to black gates-which leaves maybe changing the volume pot, and a teflon bypass for the coupling caps).
Dave
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Teflon caps to bypass PIO output caps...
I have a pair...
How I wish I kept the bigger plastic plate of the Quickie, now I have some space issues to accomodate them! >:(
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Bonzo,
How do you like the teflon? The PIOs are really nice, but I wonder what the teflon would do to the sound (PIO seemed to take some of the bass out, which the black gates brought back, but not completely).
Dave
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How do you like the teflon? The PIOs are really nice, but I wonder what the teflon would do to the sound (PIO seemed to take some of the bass out, which the black gates brought back, but not completely).
Ciao Dave,
Sorry if I wasn't clear: I have the Teflon caps but I cannot fit them in my quickie due to lack of space (but I promise I'll do my best to fit them). Bypassing a PIO with a Teflon cap could, IMHO, restore both a bit of bass and a bit of high, it's the same improvement I heard on my phono pre (where I was able to fit both PIO and Teflon) and also reported here: http://www.enjoythemusic.com/diy/0411/capacitor3.htm (http://www.enjoythemusic.com/diy/0411/capacitor3.htm)
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Sounds like that might be the answer! How about placing another box below the Quickie to make room for the teflons?
8)
Dave
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If were talking Russian Teflons the K72's are fairly compact and should be easy to fit. e.g. here is a 2.2uf K75-10 with a .022 K72-6 i used in one of my amps. I found with the K75's on their own to be dark sounding, adding the K72's brought back the high end detail. I'm usually not a fan of bypassing caps but in this case it worked rather well.
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i'm curious to see if the teflons would change the bass too.. That's the main thing i'd like to see come back a little more. The black gate bypass caps aren't burnt in yet (I feel funny about using up battery power to burn in caps; they only have 30 hours on them out of ~400).. Probably should let those burn in !
Dave
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Going to say no. The small capacity .022uf will only pass high frequencies and do little to nothing for the low end. To me the K75's roll off both ends of the spectrum, their strong point being the rich mid range tone. It was because of that lack of low end i removed them.
I would suspect a basic Mundorf or Solen MKP would perform better overall. I tried a bunch of 2.2uf caps in my Quickie and ended up staying with the ClarityCap ESA, and for $8 each they are reasonably priced too. Then again the Mundorfs and Solens are half that price and almost as good. Any of them will have better low end than the K75's IMO.
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Going to say no. The small capacity .022uf will only pass high frequencies and do little to nothing for the low end.
Just a question: the resistance across the output rca of the quickie (if I remember correctly) is 220kohm, so with a 0.022uf cap the cutoff frequency of the rc filter would be 33hz. It seems, by my calculation, that the teflon bypass cap could pass also some bass frequencies, or did I completely miss the point?
I haven't considered amp's input impedance, assuming it was pretty high like all Bottlehead's kit (with a low input impedance amp, the cutoff frequency would rise a lot).
Ciao!
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I haven't considered amp's input impedance
That is certainly worth considering. It isn't uncommon to see an amp with a 10K input impedance.
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That is certainly worth considering. It isn't uncommon to see an amp with a 10K input impedance.
Yes,
you're right, but I assumed we're speaking about Bottlehead's amp, so with a minimum of 60k.
When paired with low input impedance amp (for example a DIY SIT L'amp ::) ) bigger caps are needed!
Thank you!
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Just a question: the resistance across the output rca of the quickie (if I remember correctly) is 220kohm, so with a 0.022uf cap the cutoff frequency of the rc filter would be 33hz. It seems, by my calculation, that the teflon bypass cap could pass also some bass frequencies, or did I completely miss the point?...
That is technically true, assuming a similarly high input impedance for the following amplifier. However, the impedance to ground of the "hot" lead is very high, making it sensitive to electric and electromagnetic fields - also known as hum and noise.
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That is technically true, assuming a similarly high input impedance for the following amplifier. However, the impedance to ground of the "hot" lead is very high, making it sensitive to electric and electromagnetic fields - also known as hum and noise.
Now I lost the track! :-[
Paul, do you mean the design of the quickie is likely to be sensitive to hum, period, or that is better to use a low impedance amp with it to reduce hum (and so is better to use bigger teflon caps to hear their contribution even to bass frequencies)?
Sorry for the dumb question! :)
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I modded the Quickie with Clarity MR Series .022 caps. The Stereomour, running wide open, using a Mallard 12AT7, has a slight amount of hum. Much more so with the JJ's or the Psvane.
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That is certainly worth considering. It isn't uncommon to see an amp with a 10K input impedance.
Interestingly, I have an amp with 10k input impedance.. So does that mean the rolloff frequency would be lower with that? The bass isn't bad, I just wish there was a little more sometimes.. Maybe a subwoofer would fix this (got a few laying around).
Dave
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Now I lost the track! :-[
Paul, do you mean the design of the quickie is likely to be sensitive to hum, period, or that is better to use a low impedance amp with it to reduce hum (and so is better to use bigger teflon caps to hear their contribution even to bass frequencies)?
Sorry for the dumb question! :)
Hah - I'm sorry for the unclear post, so we're even :^)
For the best noise sensitivity, the coupling cap impedance should be less than the source impedance of the preamp (about 2K ohms for the stock Quickie, 4K with the PJCCS), at the lowest frequency of interest for noises. That places the "hot" interconnect line at the lowest possible impedance to ground, enabling it to minimize electric field (capacitive) coupling.
My usual rule is to make the cap impedance less than the source resistance at 120Hz. I also check that the response corner for the lowest rated load impedance is 5Hz or lower. These are two different and independent criteria, and are occasionally over-ridden by listening tests - I love science but it is not everything.
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Interestingly, I have an amp with 10k input impedance.. So does that mean the rolloff frequency would be lower with that? The bass isn't bad, I just wish there was a little more sometimes.. Maybe a subwoofer would fix this (got a few laying around).
Dave
If you have a tiny cap at the output of the Quickie and a 10K input impedance on your power amp, you'll get bass rolloff.
The output impedance of the Quickie is also a tad high for a 10K load, but this is more about distortion rather than frequency response.
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Hah - I'm sorry for the unclear post, so we're even :^)
For the best noise sensitivity, the coupling cap impedance should be less than the source impedance of the preamp (about 2K ohms for the stock Quickie, 4K with the PJCCS), at the lowest frequency of interest for noises. That places the "hot" interconnect line at the lowest possible impedance to ground, enabling it to minimize electric field (capacitive) coupling.
My usual rule is to make the cap impedance less than the source resistance at 120Hz. I also check that the response corner for the lowest rated load impedance is 5Hz or lower. These are two different and independent criteria, and are occasionally over-ridden by listening tests - I love science but it is not everything.
OK, now I got it, thank you very much Paul! Now I have a way to calculate the output cap value by myself! 8)
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If you have a tiny cap at the output of the Quickie and a 10K input impedance on your power amp, you'll get bass rolloff.
The output impedance of the Quickie is also a tad high for a 10K load, but this is more about distortion rather than frequency response.
The output caps are 2uf Russian K75-10s, shouldn't be an issue with rolloff, right? (Except the inherent k75 bass rolloff).
Dave
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To calculare bass rolloff (cutoff frequency) you can apply the same formulae for a simple RC high pass-filter.
You can use this calculator, for example http://sim.okawa-denshi.jp/en/CRhikeisan.htm (http://sim.okawa-denshi.jp/en/CRhikeisan.htm)
Use power amp's impedance for "R" and output cap's value for "C"; please bear in mind that when you use two caps in parallel you have to sum their capacitance value and use this value for "C".
Hope it helps!
Ciao
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Also, if you have a bleeder resistor after the output cap it is in parallel with the amp's input. So get the parallel equivalent first then plug into the formula.
With just two resistors product over sum works. (R1)*(R2)/R1+R2
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Hi,
Thanks for the ideas, just realized why there was no bass. Before adding the bypass caps, I set the eq in itunes to treble booster, which makes the bass flat. After turning off the eq, bass is back! Oops! lol.
Dave
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Ok, some feedbacks for the big tubes
Tubes #1: metal base
The gain is really high..I think you can expect 3db more gain from the quickie, but you'll also pick up a lot of hum.
It's not so simple to enjoy music with them, you have to use an amplifier with low gain (absolutely less than 20db)
Tubes #2: normal plastic base
A touch less gain (very strange, they are supposed to be te same model!), so you can use them with a normal amplifier
How do they sound? As they exhibit more gain, they seem to sound better (i.e. louder), but once you balance the volume you'll hear some bass rolloff. I use fostex fullrange, so I don't need a bass-shy preamp!
Midrange is really good, detailed and a bit sharp, voices are really good
Highs are a good.
Soundstage is good too, a bit flat but good nonetheless...
Did I tell you there is also the "glow factor"?!? ;D
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Some more updates:
Still wondering how can a simple tube swap made the quickie almost twice as powerful (but I suspect the distortion is double too...).
In any case I recommend this particulare "tube swapping": not only the look is really cool, but the mod maintains the sound signature of the Quickie.
I would have kept this setup if I hadn't a pair of Telefunken ;)
Ciao!
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ok,
some free time and some monster cap to play with: what do you think if I use 37uf PIO western electric caps for cathode bypass?
I red somewere minimum value should be 47uf...how much bass rolloff would I experience?
Thank you very much for any help!
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Hi everybody, a little bump for my question:
do anyone here can give me some ads about using 37uf PIO western electric caps for cathode bypass?
I red somewere minimum value should be 47uf, but I also red there could be no caps too, albeit there would be less gain.
Thank you very much for your help!
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This is another quote from PJ:
I think around 40uF should be satisfactory. The 1000uF is just something big enough to not lose on the workbench :^) seriously, at that low a voltage the cap is very cheap.
So maybe 37uf is ok, BUT having red this article http://www.rfcafe.com/references/popular-electronics/bypass-capacitor-jan-1962-popular-electronics.htm (http://www.rfcafe.com/references/popular-electronics/bypass-capacitor-jan-1962-popular-electronics.htm) it seems the smallest value to achieve a good reactance (1/20 of Rk) and a 10Hz bottom freq. is 380uf.
Mmmmhhh....
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A little bump for my old question...
The point is the PIO caps I have are really huge, and to try them means to rebuild my quickie once again, so before made this huge amount of work I'd like to know in advice if the value of the caps is ok.
From what I red in the forum 47/40 uf is ok (so 37uf should be ok too), but from the formulae I found on the net it seems not...
Obviously I trust the man who designed the Quickie ;D but, as I said, the huge amount of work involved in the mod makes me think twice... ::)
Ciao!
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There are numerous different formulations of the "proper" cathode bypass capacitance. They differ because they each use different criteria and/or different simplifications of the circuit. As far as I know, nobody has published or posted real-world subjective comparisons, so the various theories remain untested. For example, the article quoted suggests a reactance 1/10th or 1/20th of the cathode resistance at the lowest frequency - which would be -0.1dB or -0.022dB. This is IMHO overkill. If you make it 1/2 of the cathode resistance you are down 1dB at the lowest frequency and the cap is 5 or 10 times smaller. You would be hard pressed to hear a 1-dB difference at 20Hz. For what it's worth, the Quickie output cap, feeding the lowest recommended load resistance of 10K, will be down about 1dB at 20Hz.
I recommend you get some clipleads to temporarily insert the caps in your current working Quickie, and do some listening to see what differences there may be. Remember that a small loss of deep bass will usually bring out the midrange, which may make it sound better at first, but a little weak eventually.
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When I was about to try out the new NOS coupling capacitor, my quickie started to behave strangely.
I was listening to a piano solo cd when all of a sudden it seemed there was a snare drum near the piano, with the snare sizzling on every loud note palyed.
I came nearer the loudspeakers and I heard a sort of high pitch hum, that increase ad the music got louder.
After some time I started hearing loud pops, like someone turned on and off the quickie.
I double checked each solder joint, tested continuity, cleaned the sockets with dry contact cleaner, cleaned pins of the tubes but it seems I cannot get rid of the sizzling and, during the first 10minutes of playing, some loud pops.
Any help is really appreciate!
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Battery voltages ok?
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Yes, plenty of voltage, alco checked continuity of the battery holders... >:(
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Is it on both channels? Does it go away with the inputs disconnected?
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The sizzle is on both channels, the pop only on one channel (also swapping tubes the channel is the same).
It's the same with inputs disconnected, and also changing inputs it remains the same.
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For battery voltage, you checked both filament and plate supplies?
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Yes, checked both filament and B+ and they are both good (1,4 v filament and 32v b+).
Another weird thing happened yesterday night: I removed the Quickie from the system and turned it upside down to inspect soldering once again. Everything was fine so I switched it on trying to ear any strange noise while gently touch components.
I was using the quickie as headphones aplifier for this task (I built Edcor transformer in a separate case).
No noises, no sizzling, just music.
Put the pre back into the system and...no more sizzling nor pops... >:(
I will investigare further this evening...
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It's most likely a damaged capacitor or it could be a loose piece of wire or something that fell out when you turned the preamp over.
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It's most likely a damaged capacitor or it could be a loose piece of wire or something that fell out when you turned the preamp over.
Thank you all for the help, I really cannot understand what's wrong!
I think the problem is still something related to sockets: now after some more cleaning and tube swapping the sizzling is less evident, and the pops stopped within 30 seconds after turning on.
Quickie's output caps are russian K75, big as a grenade, I don't tink they are damaged, but I'll change them just to be shure.
ATM I'm using the quickie with a class D amp which has big electrolytic output capacitors, maybe is a good idea to check if they are damaged too, and maybe bypass them with good teflon ones?
Thank you all again! :) :) :)
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I was working under assumption that you were sure the noise was coming from the preamp. If you haven't already, you will want to isolate which piece of gear the noise is coming from before changing out any parts.
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I was working under assumption that you were sure the noise was coming from the preamp. If you haven't already, you will want to isolate which piece of gear the noise is coming from before changing out any parts.
You were right Doc, the pops and the sizzling sound are from the quickie without any dubts (tested with headphones and no amplifier connected), I was thinking if also the power amp could exacerbate the problem with those big electrolytic output caps...
Thank you
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Another thing felt into my mind today: could it be possible it's a switch problem?
My Quickie is the old version with TPDT switch for power on.
Mmmh...
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Bonzo,
How about switching out the tubes?
Dave
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Bonzo,
How about switching out the tubes?
Dave
Hi Dave, the pops remain int he right channel even when I change tubes and also after tube rolling...
Thank you for the hint anyway! :)
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In my search to get rid of the pops, my father gave me an old "secret" dated back when there were valves in the TV.
To avoid the valves loose connection during time, it was a common practice among technicians to gently bend outwards a little all tube pins.
It seems to work for me: sizzle is still there (but now I can ear it only whit acoustic piano) and pops are almost gone.
Hope it helps other forumers too!
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Hi Dave, the pops remain int he right channel even when I change tubes and also after tube rolling...
Thank you for the hint anyway! :)
I figured with all of the tubes you posted pics of there were some laying around lol 8)