Hello all, does anybody know when the time is to change the valves ? Not sure what the symptoms of telling would be.
Midrange has become rather grainy and glary of late, especially with vocals, perhaps down to my ageing ears. Would the mid sound glary if the valves were on their way out ?
Thanks
Midrange has become rather grainy and glary of late, especially with vocals, perhaps down to my ageing ears. Would the mid sound glary if the valves were on their way out ?
Thanks
Yaquin SD CD3 tube buffer, a vexing issue
Hello again. Hope you like the schematic.
I'm not a tech, though I've built some kits in my time. I'd appreciate some observations and corrections from the techs in residence.
First, judging from the schematic I've submitted, I'd say that all the capacitors and the 680 & 100K resistors are in the signal path. I concluded that the 20K resistor is not. I'd appreciate any corrections.
Second, in the interest of properly orienting any capacitor upgrades, could someone point out the source and destination or ground sides of the capacitor positions judging from the supplied schematic?
Third, a very vexing issue. There's no damn difference whether my unit is on or off. That is, the system continues to play music when I shut off power to the Yaquin. There's no sonic difference whether on or off. When the unit is turned on, it's 'instant on' with no tube warm up, or turn-on thumps, and likewise when I turn the Yaquin off, there is no shut-down thump and the music continues to play merrily along.
Is it plausible that this unit acts as a 'straight wire' connection when powered down? Or have we been scammed? It just seems improbable that an active circuit would behave like this.
My connection scheme is DAC > Yaquin buffer > passive stepped attenuator > amp.
Any help is more than appreciated.
Hello again. Hope you like the schematic.
I'm not a tech, though I've built some kits in my time. I'd appreciate some observations and corrections from the techs in residence.
First, judging from the schematic I've submitted, I'd say that all the capacitors and the 680 & 100K resistors are in the signal path. I concluded that the 20K resistor is not. I'd appreciate any corrections.
Second, in the interest of properly orienting any capacitor upgrades, could someone point out the source and destination or ground sides of the capacitor positions judging from the supplied schematic?
Third, a very vexing issue. There's no damn difference whether my unit is on or off. That is, the system continues to play music when I shut off power to the Yaquin. There's no sonic difference whether on or off. When the unit is turned on, it's 'instant on' with no tube warm up, or turn-on thumps, and likewise when I turn the Yaquin off, there is no shut-down thump and the music continues to play merrily along.
Is it plausible that this unit acts as a 'straight wire' connection when powered down? Or have we been scammed? It just seems improbable that an active circuit would behave like this.
My connection scheme is DAC > Yaquin buffer > passive stepped attenuator > amp.
Any help is more than appreciated.
Simplistically its a straight piece of wire. If you have a source impedance of say 1K, you have effectively 1K//100K and 20k to gnd ie a potential divider with 1k and 20k. The input is to the 1k and the output from the centre tap.
When powered on, the input inpedance is Zin = Rg / (1 - Av * (Rl / Rl + Rb))
For a better explanation see
The Valve Wizard -Cathode Follower
Regards
John
When powered on, the input inpedance is Zin = Rg / (1 - Av * (Rl / Rl + Rb))
For a better explanation see
The Valve Wizard -Cathode Follower
Regards
John
I screwed up - see see attachment, this is the equivalent - but its still abit of wire
Similar : http://www.diyaudio.com/forums/tubes-valves/96681-tube-buffer-6j1-5654-6ak5.html
Similar : http://www.diyaudio.com/forums/tubes-valves/96681-tube-buffer-6j1-5654-6ak5.html
Attachments
More on the Yaquin
Cookj, thank you for the response.
I originally began this little experiment with the idea that I could add a dusting of powdered sugar to my strawberries. That is, that I could get a bit of the classic tube magic added to the sound of an otherwise very revealing and transparent system. [Bryston 28bSST2 amps, “Ultimate Attenuators,” ([/SIZE][/FONT]http://www.tweakaudio.com/Ultimate%20Attenuators.html) and a Monarchy DAC which still serves up red book CDs as well as anything else I’ve heard, and Volent Paragon 3.5 speakers. The system is not bright by any means, but I wanted the ability to go back and forth, with or without the buffer as dictated by mood or by software.
Is the Yaquin AC or DC coupled? If I am not jumping to conclusions, judging by your comments and this quotation from the article you referred me to, the tube buffer stage is solely and only for impedance matching and will not impart the same qualities to the signal as a tube circuit with gain: “The cathode follower is an excellent buffer stage for driving a tone stack or effects loop, or any circuit which would otherwise present a heavy load to a "normal" stage. In addition, the DC-Coupled cathode follower can also be used to produce a unique compressive quality, and is to be found in most of the classic amp designs. The AC-coupled version is not so useful for this, since the input-coupling cap prevents the flow of quiescent grid current. The AC-coupled version is therefore used as a tonally transparent stage, usually.”
It would therefore be essentially useless to engage in tube rolling with expensive classic tubes, or to upgrade caps and resistors.[/U] I don’t mind being told I’m barking up the wrong tree. I’ve wasted more money on bad CDs and records. But have I reached the right conclusions? As I’ve stated in my previous post, I hear no difference with the buffer on or off, so why not eliminate the added circuitry? There are no impedance matching problems with my system in a simple ‘passive preamp’ mode.
Cookj, thank you for the response.
I originally began this little experiment with the idea that I could add a dusting of powdered sugar to my strawberries. That is, that I could get a bit of the classic tube magic added to the sound of an otherwise very revealing and transparent system. [Bryston 28bSST2 amps, “Ultimate Attenuators,” ([/SIZE][/FONT]http://www.tweakaudio.com/Ultimate%20Attenuators.html) and a Monarchy DAC which still serves up red book CDs as well as anything else I’ve heard, and Volent Paragon 3.5 speakers. The system is not bright by any means, but I wanted the ability to go back and forth, with or without the buffer as dictated by mood or by software.
Is the Yaquin AC or DC coupled? If I am not jumping to conclusions, judging by your comments and this quotation from the article you referred me to, the tube buffer stage is solely and only for impedance matching and will not impart the same qualities to the signal as a tube circuit with gain: “The cathode follower is an excellent buffer stage for driving a tone stack or effects loop, or any circuit which would otherwise present a heavy load to a "normal" stage. In addition, the DC-Coupled cathode follower can also be used to produce a unique compressive quality, and is to be found in most of the classic amp designs. The AC-coupled version is not so useful for this, since the input-coupling cap prevents the flow of quiescent grid current. The AC-coupled version is therefore used as a tonally transparent stage, usually.”
It would therefore be essentially useless to engage in tube rolling with expensive classic tubes, or to upgrade caps and resistors.[/U] I don’t mind being told I’m barking up the wrong tree. I’ve wasted more money on bad CDs and records. But have I reached the right conclusions? As I’ve stated in my previous post, I hear no difference with the buffer on or off, so why not eliminate the added circuitry? There are no impedance matching problems with my system in a simple ‘passive preamp’ mode.
what is the purpose of having 2x0.47uF caps in parallel instead of a single 0.22uF on the output?
Parallel capacitance doubles, series halves. That's the rule of thumb.
So 2x.47uF is .94uF, so you could say about 1uF.
Yeah, you're right! that's what I really wanted to get to. Can I just replace the two caps for a single 1uF without problem?
A well-designed circuit is not meant to impart any qualities, just pass on the signal with as little damage as possible. This is a simple cathode follower, dressed up to look important (and expensive, I bet). There is nothing particularly wrong with the circuit, apart from missing ground leak resistors at the outputs. As you have found, it still passes some signal even when switched off! In most setups, it should have almost no effect on the signal apart from adding a tiny bit of noise and distortion, probably too little to notice. In most setups it is unnecessary, as there is no impedance problem to solve so it can only be used for cosmetic reasons.
Given the relatively high input impedance (the 100K resistors are bootstrapped, so look much higher in value), changing the input caps will not affect the sound unless you go to much lower values. The output caps need to be big enough to cope with whatever follows. 1uF with a 20K input impedance next will give 8Hz rolloff.
This circuit is AC coupled at both input and output.
Given the relatively high input impedance (the 100K resistors are bootstrapped, so look much higher in value), changing the input caps will not affect the sound unless you go to much lower values. The output caps need to be big enough to cope with whatever follows. 1uF with a 20K input impedance next will give 8Hz rolloff.
This circuit is AC coupled at both input and output.
the schematic has a small error in it. The 1uF output capacitor should be connected directly to pins 6 and 3 of the vacuum tube. Please correct me if I am wrong.
Thanks
Thanks
Cookj, DF96 ]
You guys have helped immeasurably. It's the first major purchasing mistake in audio I've made in decades. And it's because I didn't understand the design basics or what I could expect (not expect, actually) from an A/C coupled cathode follower. To make matters worse, the thing has gone dead after about 75 hours of use - perhaps in revenge for being exposed on the net. I now have to deal with a Hong Kong dealer about a return or repair.
Live and learn boys, live and learn.
Cookj, DF96 ]
You guys have helped immeasurably. It's the first major purchasing mistake in audio I've made in decades. And it's because I didn't understand the design basics or what I could expect (not expect, actually) from an A/C coupled cathode follower. To make matters worse, the thing has gone dead after about 75 hours of use - perhaps in revenge for being exposed on the net. I now have to deal with a Hong Kong dealer about a return or repair.
Live and learn boys, live and learn.
Need your advice
Hi Singa - I have received a quote from a mod head recently. He recommends 4 x 0.47uf 1200VDC Mundorf Silver oil and 2 x 0.1uf 1200VDC Supreme including Silver UPOCC internal wires at $320.
He also said if I want the top grade he recommends Silver/Gold Oil 4 x 0.47uf with an additional $160. Would there be a significant improvement in sound? If yes, at what percentage do you think it might be?
I just thought it is a bit too much for the upgrading and maybe I should consider buying a new tube amplifier (Yaqin MC100B) which received rave reviews.
Any input from you would be much appreciated.
Hi,
Because capacity is doubled you have a lower low frequency extension
so you will hear more bass which is better.singa
PS there is no necessity to change the 4 power decoupling caps as it will
not have a significant improvement or none at all.A upgrade to mundorf
silver/gold or silver/gold in oil or at least silver in oil will be worth your while.
Hi Singa - I have received a quote from a mod head recently. He recommends 4 x 0.47uf 1200VDC Mundorf Silver oil and 2 x 0.1uf 1200VDC Supreme including Silver UPOCC internal wires at $320.
He also said if I want the top grade he recommends Silver/Gold Oil 4 x 0.47uf with an additional $160. Would there be a significant improvement in sound? If yes, at what percentage do you think it might be?
I just thought it is a bit too much for the upgrading and maybe I should consider buying a new tube amplifier (Yaqin MC100B) which received rave reviews.
Any input from you would be much appreciated.
Hello
I 've got the Yaqin sd-cd 3 buffer as well, and I need a little help here.
I want to upgrade the caps with some PIO but I only have got 2 x 0.22 uf and 4 x 0.68 uf and no 0.47 uf.
Can anyone tell me if it could be a problem to replace the 4 x 0.47 uf caps with 4 x 0.68 uf ?
Can I blow the Yagin or what could happen?
Best regards
Blackieheil
I 've got the Yaqin sd-cd 3 buffer as well, and I need a little help here.
I want to upgrade the caps with some PIO but I only have got 2 x 0.22 uf and 4 x 0.68 uf and no 0.47 uf.
Can anyone tell me if it could be a problem to replace the 4 x 0.47 uf caps with 4 x 0.68 uf ?
Can I blow the Yagin or what could happen?
Best regards
Blackieheil
valves rolling
isn't the tube used a RUssian 6n8s? If so, try 6sn7 or possibly even 6N16B-V pencil tubes. Or splice in 7193 tube with anode and grid leads per single triode.
I would try caps bypassing and PSU updates first.
Me? I'm heading towards trying the Broskie Unbalancer circuit with stepped attenuaters at outputs. It has gain and the output stage is Broskie Cathode follower circuit. Gotta get RID of most of that gain. You can feed a V-out DAC into the Unbalancer with NO CAPS, it should ignore the midrail phantom DC riding on the DAC outs pins.
isn't the tube used a RUssian 6n8s? If so, try 6sn7 or possibly even 6N16B-V pencil tubes. Or splice in 7193 tube with anode and grid leads per single triode.
I would try caps bypassing and PSU updates first.
Me? I'm heading towards trying the Broskie Unbalancer circuit with stepped attenuaters at outputs. It has gain and the output stage is Broskie Cathode follower circuit. Gotta get RID of most of that gain. You can feed a V-out DAC into the Unbalancer with NO CAPS, it should ignore the midrail phantom DC riding on the DAC outs pins.
Hi and thanks for the advice on rolling the valves. Been away for some months so hence the late reply !
Been trawling the web for info and does seem that replacing them with 6SN7s would be a good choice. But there still a lot to choose from it seems. Any ideas on narrowing this down further ?
Will probably buy from here and they have a reasonable selection on offer but not sure what 6SL7s are:
Octal pre/driver valves - Hifi Collective
Been trawling the web for info and does seem that replacing them with 6SN7s would be a good choice. But there still a lot to choose from it seems. Any ideas on narrowing this down further ?
Will probably buy from here and they have a reasonable selection on offer but not sure what 6SL7s are:
Octal pre/driver valves - Hifi Collective
Yaqin CD3 tube rolling
From what I have read, AFTER you bypass all the coupling caps and add maybe some photo_flash caps to the PSU and also some bypass caps at PSU.... then maybe try a 7193 Triode in each bay, after verifying what socket wiring might need to change and changing that. THAT is documented HERE:
AudiogoN Forums: Supratek Owners - Simple Mod to Run 7193 Tubes
for top caps either buy ones on the net or use small worm-drive clamps?
Also, testing a pair of 6n16B-V tubes would be pretty easy, as I recall Yaqin parallels the triodes in each tube. Figure THAT out easy enough.
You CAN also make 6CG7 socket adapters but... I bet the 7193 would play better.
Off topic, I did make a PCB for The Unbalancer using 6N16B-V tubes, but have had no time to try. The differential input to Broskie's Unbalancer means no input caps required. Should be quite revealing. With QUITE a bit of rewiring you COULD probably add the front end of the Broskie circuit to the CD3 and use the big tubes in a Broskie Cathode-follower configuration [the output stage of Broskie's "Unbalancer"]... you would "un-parallel" the triodes in the stock tube config and rewire.
From what I have read, AFTER you bypass all the coupling caps and add maybe some photo_flash caps to the PSU and also some bypass caps at PSU.... then maybe try a 7193 Triode in each bay, after verifying what socket wiring might need to change and changing that. THAT is documented HERE:
AudiogoN Forums: Supratek Owners - Simple Mod to Run 7193 Tubes
for top caps either buy ones on the net or use small worm-drive clamps?
Also, testing a pair of 6n16B-V tubes would be pretty easy, as I recall Yaqin parallels the triodes in each tube. Figure THAT out easy enough.
You CAN also make 6CG7 socket adapters but... I bet the 7193 would play better.
Off topic, I did make a PCB for The Unbalancer using 6N16B-V tubes, but have had no time to try. The differential input to Broskie's Unbalancer means no input caps required. Should be quite revealing. With QUITE a bit of rewiring you COULD probably add the front end of the Broskie circuit to the CD3 and use the big tubes in a Broskie Cathode-follower configuration [the output stage of Broskie's "Unbalancer"]... you would "un-parallel" the triodes in the stock tube config and rewire.