This is very interesting. Some days ago i played around and tryed to connect my CDP direct with Zen V4 instead of using my BOZ. Disadvantage is no volume control, so it is a little loud, but the impression was it sounds better without the preamp.
I took a look in the manual for the DAC in the CDP:
http://www.daisy-laser.nl/homeoptics/tda1305t.pdf
and it says minimum R load is 3k. What value for Volume pot shoul i use between TDA1305 and ZEN v4, cables are about 0,5m from CDP to Volume control and 0,5m to ZEN V4. I don´t need source switches, i want to connect only the CDP, nothing else. Do i need any of the additional coupling C´s ? for what purpose, and why the 1M reswistors??
Thanks, Till
I took a look in the manual for the DAC in the CDP:
http://www.daisy-laser.nl/homeoptics/tda1305t.pdf
and it says minimum R load is 3k. What value for Volume pot shoul i use between TDA1305 and ZEN v4, cables are about 0,5m from CDP to Volume control and 0,5m to ZEN V4. I don´t need source switches, i want to connect only the CDP, nothing else. Do i need any of the additional coupling C´s ? for what purpose, and why the 1M reswistors??
Thanks, Till
Til,
I would go for 5k log pot if you can find a
good quality one but otherwise use a 10k log.
With only 0.5M of cable (after the pot) you
should get good results.
Computing turnover frequency.
-----------------------------------
The maximum output impedance will be about
half the value of the pot, call this RV/2.
If the load capasitance is C
(pF per metre of cable after the pot * length of cable + amplifier input capasitance)
then :-
Xc=1 / (2*Pi*F*C)
Let Xc=RV/2
exchange Xc and F
cancel out the 2's ->
F (-3db point) = 1 / (Pi*Rv*C)
Bobken's ears
tell us this should
be at least 200kHz for undetectable
attenuation
Dave
I would go for 5k log pot if you can find a
good quality one but otherwise use a 10k log.
With only 0.5M of cable (after the pot) you
should get good results.
Computing turnover frequency.
-----------------------------------
The maximum output impedance will be about
half the value of the pot, call this RV/2.
If the load capasitance is C
(pF per metre of cable after the pot * length of cable + amplifier input capasitance)
then :-
Xc=1 / (2*Pi*F*C)
Let Xc=RV/2
exchange Xc and F
cancel out the 2's ->
F (-3db point) = 1 / (Pi*Rv*C)
Bobken's ears
tell us this should be at least 200kHz for undetectable
attenuation
Dave
Gaz
I would say, give it a try and find out for yourself if it's worth the effort!
That's the way I'v learn to deal with electronics.
If it's to expensive, try it out with cheaper and/ or used parts. If it sounds great, use better parts, if not, at least you know that the guy's who told you not to do that where right. Remember " The proof of the (Electronic)pudding is in the (audio-hearing)eating!
All the best and don't giveup!
We are here to help you!
Audiofanatic!
I would say, give it a try and find out for yourself if it's worth the effort!
That's the way I'v learn to deal with electronics.
If it's to expensive, try it out with cheaper and/ or used parts. If it sounds great, use better parts, if not, at least you know that the guy's who told you not to do that where right. Remember " The proof of the (Electronic)pudding is in the (audio-hearing)eating!
All the best and don't giveup!
We are here to help you!
Audiofanatic!
Bobken's ears tell us this should
be at least 200kHz for undetectable
attenuation
Dave [/B][/QUOTE]
Hi,
I only wish that was true!
Regrettably due to advancing years my threshold for pure tones runs out not much higher than 10kHz, but Rarkov's should be nearer 16kHz, I would have thought.
However, interestingly, I can still hear the effect of curtailing the frequencies at say 40kHz, which seems to rob the sound of 'air', for want of a better expression, and some recording venue ambience, which detracts from the overall enjoyment of listening.
This particular phenomenon is well recognised in audio circles, and very likely relates to some kind of 'beat' effects, due to some harmonics which have been removed.
I have built many passive pot arrangements and some switched type attenuators, the nicest-sounding of which I still use from time-to-time.
This was constructed with the very best available components I am aware of (a silver contact Shallco switch and all Vishay bulk foil resistors), but good-sounding though it may be, it is still, unfortunately, subject to the normal laws of physics.
The maximium output resistance is only 13.5kHz, but at near full volume, I (originally) noticed this quite obvious loss of 'air' around instruments and performers, which I mentioned.
With my (then) 300pF capacitance interconnects, I calculated the 3dB point which was about 39kHz, and I was puzzled by what I heard. I also checked it out on my 'scope which indicated about 40k, so there was no other un-accounted-for effects, but it was clearly audible to me, in its effect on the sound.
Also, looking at the 'scope trace for a while it became apparent that the signal level *commenced* rolling off much lower than this, and it didn't take me long to figure out why. As I said, from calculation it actually commenced at a decade lower, i.e. at about 4khz, which is well within my (restricted) threshold!
I only overcame this problem in the end by making up some very low capacitance (30pF) DIY 'output' cables, and I can not now hear any loss of ambience with this passive attenuator.
With Rarkov's proposed arrangement very likely showing a *half power* output at merely 10.6 kHZ (and roll-off commencing at 1kHz), it seemed very wise to me to get Rarkov to look into the matters I had suggested, since he said he had already been dissatisfied following the first attempt he had made.
There must be very many references to passives available, as I constantly come across them by accident, and as Rarkov has his own electronics web site, now seems to be good time for him to fully appreciate the basic engineering matters to be taken into account here.
As I said several times before, I don't wish to deter Rarkov in any way, and of course more or less *anything* will *do*, but if he wishes to make a good job this (the second!) time, he cannot ignore the relevent requirements and limitations.
Regards,
tell us this should be at least 200kHz for undetectable
attenuation
Dave [/B][/QUOTE]
Hi,
I only wish that was true!
Regrettably due to advancing years my threshold for pure tones runs out not much higher than 10kHz, but Rarkov's should be nearer 16kHz, I would have thought.
However, interestingly, I can still hear the effect of curtailing the frequencies at say 40kHz, which seems to rob the sound of 'air', for want of a better expression, and some recording venue ambience, which detracts from the overall enjoyment of listening.
This particular phenomenon is well recognised in audio circles, and very likely relates to some kind of 'beat' effects, due to some harmonics which have been removed.
I have built many passive pot arrangements and some switched type attenuators, the nicest-sounding of which I still use from time-to-time.
This was constructed with the very best available components I am aware of (a silver contact Shallco switch and all Vishay bulk foil resistors), but good-sounding though it may be, it is still, unfortunately, subject to the normal laws of physics.
The maximium output resistance is only 13.5kHz, but at near full volume, I (originally) noticed this quite obvious loss of 'air' around instruments and performers, which I mentioned.
With my (then) 300pF capacitance interconnects, I calculated the 3dB point which was about 39kHz, and I was puzzled by what I heard. I also checked it out on my 'scope which indicated about 40k, so there was no other un-accounted-for effects, but it was clearly audible to me, in its effect on the sound.
Also, looking at the 'scope trace for a while it became apparent that the signal level *commenced* rolling off much lower than this, and it didn't take me long to figure out why. As I said, from calculation it actually commenced at a decade lower, i.e. at about 4khz, which is well within my (restricted) threshold!
I only overcame this problem in the end by making up some very low capacitance (30pF) DIY 'output' cables, and I can not now hear any loss of ambience with this passive attenuator.
With Rarkov's proposed arrangement very likely showing a *half power* output at merely 10.6 kHZ (and roll-off commencing at 1kHz), it seemed very wise to me to get Rarkov to look into the matters I had suggested, since he said he had already been dissatisfied following the first attempt he had made.
There must be very many references to passives available, as I constantly come across them by accident, and as Rarkov has his own electronics web site, now seems to be good time for him to fully appreciate the basic engineering matters to be taken into account here.
As I said several times before, I don't wish to deter Rarkov in any way, and of course more or less *anything* will *do*, but if he wishes to make a good job this (the second!) time, he cannot ignore the relevent requirements and limitations.
Regards,
ATTENUATED...
Hi,
For those wanting to look into the topic of attenuators and passive preamps there are at least a dozen threads about it in various sections;
Solid State,Everythings Else...etc.
Just doing a search on "Attenuator" will yield a few pages already.
Rarkov's hearing could well be into the 20kHz range but as Bob states correctly IME,you can still easily discern HF roll offs well over 50KHz.
Cheers,
Hi,
For those wanting to look into the topic of attenuators and passive preamps there are at least a dozen threads about it in various sections;
Solid State,Everythings Else...etc.
Just doing a search on "Attenuator" will yield a few pages already.
Rarkov's hearing could well be into the 20kHz range but as Bob states correctly IME,you can still easily discern HF roll offs well over 50KHz.
Cheers,
Hiya,
Thanks for all your help. Bobken - I'm not ignoring yours, or anyones advice - but I am guilty of glossing over things I don't really understand! I really shouldn't be doing an electroncis degree - but there you go! 
I think that Audiofanatic gives good advice, and I will try a few things. But here is a shocker for you...When I was young I burst my eardrums twice (my brother shouted in my ear as a baby and the other time I can't remember what happened)...I forgot about these, but when I was diving recently, at about 20m under, it burst again. Apart from being exceedingly painful - my hearing isn't fantastic! I would expect (although I have not yet conducted tests) that my hearing rolls off quite early. If anyone knows the effect of burst ear drums on hearing - I'd be interested in hearing it.
I am going to take your advice and get some cheap 10k 50k and my expensive 100k pots and have ago.
I will also try the unity gain buffer. Where would I put that in? Just after the volume or before or both?!
Thanks for all your help!
Gaz
Thanks for all your help. Bobken - I'm not ignoring yours, or anyones advice - but I am guilty of glossing over things I don't really understand!
I really shouldn't be doing an electroncis degree - but there you go! I think that Audiofanatic gives good advice, and I will try a few things. But here is a shocker for you...When I was young I burst my eardrums twice (my brother shouted in my ear as a baby and the other time I can't remember what happened)...I forgot about these, but when I was diving recently, at about 20m under, it burst again. Apart from being exceedingly painful - my hearing isn't fantastic! I would expect (although I have not yet conducted tests) that my hearing rolls off quite early.
If anyone knows the effect of burst ear drums on hearing - I'd be interested in hearing it.I am going to take your advice and get some cheap 10k 50k and my expensive 100k pots and have ago.
I will also try the unity gain buffer. Where would I put that in? Just after the volume or before or both?!
Thanks for all your help!
Gaz
Frequency limits
All,
When I was younger I could hear the difference between sine, square and sawtooth waveforms of around 15KHz.
Even so, my hearing could not (for sure) detect a sinewave above 19 or 20KHz.
This told me that there is more to it than meets the (eye?).
Rarkov,
My hearing is considerably "down" on what it was, but even so, I have become more fussy about what I can hear.
Cheers,
All,
When I was younger I could hear the difference between sine, square and sawtooth waveforms of around 15KHz.
Even so, my hearing could not (for sure) detect a sinewave above 19 or 20KHz.
This told me that there is more to it than meets the (eye?).
Rarkov,
My hearing is considerably "down" on what it was, but even so, I have become more fussy about what I can hear.
Cheers,
Harry Haller Passive Pre
I surprised no-one has pointed you to this long thread on the subject.
dave
I surprised no-one has pointed you to this long thread on the subject.
dave
You star!
That's exactly what I'm looking for...Now I can use my Alps 100k dual gang pot!
I have the 1% metal film resisotors so that's cool...and the rest of it is on its way!
Thanks...
I'll keep you posted about opinions...If I don't like the sound, I'll try a different approach. The preamp (modified integrated amp) starts "flapping" the speakers around at anywhere near decent volumes, yet when I use the CD player directly, it sounds great...Therefore I know it's the preamp...
As I said - I'll let you know...I'm very excited about this!
Gaz
That's exactly what I'm looking for...Now I can use my Alps 100k dual gang pot!
I have the 1% metal film resisotors so that's cool...and the rest of it is on its way!
Thanks...
I'll keep you posted about opinions...If I don't like the sound, I'll try a different approach. The preamp (modified integrated amp) starts "flapping" the speakers around at anywhere near decent volumes, yet when I use the CD player directly, it sounds great...Therefore I know it's the preamp...
As I said - I'll let you know...I'm very excited about this!
Gaz
Hi Rarkov,
What a surprise you now come up with, and I am very sorry to hear of these problems with your ears.
However, if you are studying for an EE Degree as you now admit, the calculations necessary here are very basic, and it is starting to seem that you are just not bothered to do something for yourself but you expect others to do it for you.
That's it from me then, and I wish you luck for the future as you'll surely need it, if that is your approach to problems, especially when you eventually need to earn yourself a living.
Regards,
What a surprise you now come up with, and I am very sorry to hear of these problems with your ears.
However, if you are studying for an EE Degree as you now admit, the calculations necessary here are very basic, and it is starting to seem that you are just not bothered to do something for yourself but you expect others to do it for you.
That's it from me then, and I wish you luck for the future as you'll surely need it, if that is your approach to problems, especially when you eventually need to earn yourself a living.
Regards,
whoa...where did that come from?! 
My degree is Communication & Electronic Eng (BEng Hons) but my sandwich year placement is as a systems engineer writing software for PLCs and SCADA. I much rather be using my electronics skills and keeping in touch with topics closer to my degree but life's a bitch, eh?
Anyway, as you may have gathered, my knowledge of basic electronics is rather sketchy until I get back into regular workouts of the brain...Also, there is the topic of not reinventing the wheel. When I performed a search on this subject - I didn't go back as far as I should have to find the linked article. It does discuss problems of cable interfacing, yet it uses the components I have to hand. I wouldn't blame anyone for wanting to try great reviews and simplicity over resolving a solved problem.
Please don't think that I take peoples' input for granted...I really do appreciate any help I get.
Thanks again...I'll keep you posted...
Gaz
My degree is Communication & Electronic Eng (BEng Hons) but my sandwich year placement is as a systems engineer writing software for PLCs and SCADA. I much rather be using my electronics skills and keeping in touch with topics closer to my degree but life's a bitch, eh?
Anyway, as you may have gathered, my knowledge of basic electronics is rather sketchy until I get back into regular workouts of the brain...Also, there is the topic of not reinventing the wheel. When I performed a search on this subject - I didn't go back as far as I should have to find the linked article. It does discuss problems of cable interfacing, yet it uses the components I have to hand. I wouldn't blame anyone for wanting to try great reviews and simplicity over resolving a solved problem.
Please don't think that I take peoples' input for granted...I really do appreciate any help I get.
Thanks again...I'll keep you posted...
Gaz
Hi,
"whoa...where did that come from?!" came from your post #26 where you clearly said "electronics degree".
I don't wish to fall out with you though, but why couldn't you have simply taken the advice in my very first post, reiterated several times, and finally reinforced by Frank?
You only needed to search on "passive" as I said.
Regards,
"whoa...where did that come from?!" came from your post #26 where you clearly said "electronics degree".
I don't wish to fall out with you though, but why couldn't you have simply taken the advice in my very first post, reiterated several times, and finally reinforced by Frank?
You only needed to search on "passive" as I said.
Regards,
PASSIVE.
Hi Bob,
The link Dave posted is well worth going through.
It has number of different approaches to the concept of a passive preamp and discusses a number of topics that will surely be of interest to you too.
I wish more members would read it through so that we can point to it instead of keeping rehashing our wisdom to the youngsters.
(no offense to any of you).
Later,
Hi Bob,
The link Dave posted is well worth going through.
It has number of different approaches to the concept of a passive preamp and discusses a number of topics that will surely be of interest to you too.
I wish more members would read it through so that we can point to it instead of keeping rehashing our wisdom to the youngsters.
(no offense to any of you).
Later,
No - I admit it - at 20, I do not have much practicle knowledge...but I am learning. This is a forum and whilst I certainly do not want to fall out with anyone (our prime minister is doing a good enough job for everyone!), lots of people offer conflicting (or indeed correlating) advice. It is difficult to choose between them. It just so happens that an oppertunity presented itself that solves my problem exactly.
I hope we can put any differences behind us - and get on with what matters...and I believe that is the music.
Thanks,
Gaz
I hope we can put any differences behind us - and get on with what matters...and I believe that is the music.
Thanks,
Gaz
Hi Frank,
Yes, your advice here is good and now that I am aware of this particular thread, I would in future point any enquirer to it. It would have saved me some time in attempting to help with the enquiry.
However, as I only joined the Forum myself in December, I was not aware of it before, and I did suggest at least three times that Rarkov should do a simple search for himself, as did you, but for reasons best known to himself, he didn't do this.
When he finally said he was taking an Electronics Degree (or words to that effect), I was amazed!
Regards,
Edit : Having just seen Rarkov's last post (since I typed the above) I agree with him wholeheartedly, in that it is the music that really matters.
Yes, your advice here is good and now that I am aware of this particular thread, I would in future point any enquirer to it. It would have saved me some time in attempting to help with the enquiry.
However, as I only joined the Forum myself in December, I was not aware of it before, and I did suggest at least three times that Rarkov should do a simple search for himself, as did you, but for reasons best known to himself, he didn't do this.
When he finally said he was taking an Electronics Degree (or words to that effect), I was amazed!
Regards,
Edit : Having just seen Rarkov's last post (since I typed the above) I agree with him wholeheartedly, in that it is the music that really matters.
You all might be interested in this passive preamp thread. It was inspired by Harry Haller's post.
http://www.diyaudio.com/forums/attachment.php?s=&postid=82996
It worked very well, once I added the input shunt resistor. Without it I had hum problems.
RonS
http://www.diyaudio.com/forums/attachment.php?s=&postid=82996
It worked very well, once I added the input shunt resistor. Without it I had hum problems.
RonS
Re: PASSIVE.
Hi Frank,
Just read through the entire thread, and it has taken me well over an hour!
Nothing new in it for me, but it was worth spending the time to compare my experiences with those of the others.
Hopefully Rarkov now understands why I gave him the advice I did, and I see that all of my caveats and the associated considerations I advised him about, are covered 'in spades', even though it took 10 pages of posts!
I particularly enjoyed Promitheus' referenced article from AV Extreme Mag, as I had not read this before, and I wish I had been on the Forum then, as I could have added somewhat to the information.
The very best method from the sonic viewpoint is to use an 'L' pad attenuator like I referred to earlier in this thread. This way there is merely one resistor in the signal path at any one time, and only one in shunt to ground.
I bought all the parts from Audio Synthesis in about '95, and they use all Vishays (you like these BFs, I know) and massive military style coin-silver contact Shallco switches, with 31 steps.
For two mono attenuators it cost me over £500 for the parts alone, way back then!
There really is nothing to touch these, as Martin Colloms has said many times, even recently, and they still outperform my passive Audio Synthesis 'Passion Ultimate' (like your pal's) which is nearly as good, but because of its being a remote-operated job (very much more convenient!), the quality of switching in the 'Passion Ultimate' is marginally less good. MC is quite right in awarding it a couple of points less than the dual mono manual 'Passion'.
My previous best, having tried all of the usual Panasonic, Noble, Alps, and Sfernice arrangements with law-faking resistors (like HH favours) was a Penny & Giles pot with Vishay 'law-fakers', but that pot cost over £90 about 15 years ago. This was very slightly better, if anything, than an 'L' pad made of all Holcos, which I also tried at one time.
The only attenuator which might be marginally better would be if the Vishays (or similar bulk-foils) had been surface-mount jobs, thus avoiding the (very short) leads, and I do believe that Jonathan Carr uses this arrangement in his Connoisseurs.
Once heard, never forgotten comes to mind!
Regards,
fdegrove said:Hi Bob,
The link Dave posted is well worth going through.
It has number of different approaches to the concept of a passive preamp and discusses a number of topics that will surely be of interest to you too.
I wish more members would read it through so that we can point to it instead of keeping rehashing our wisdom to the youngsters.
(no offense to any of you).
Later,
Hi Frank,
Just read through the entire thread, and it has taken me well over an hour!
Nothing new in it for me, but it was worth spending the time to compare my experiences with those of the others.
Hopefully Rarkov now understands why I gave him the advice I did, and I see that all of my caveats and the associated considerations I advised him about, are covered 'in spades', even though it took 10 pages of posts!
I particularly enjoyed Promitheus' referenced article from AV Extreme Mag, as I had not read this before, and I wish I had been on the Forum then, as I could have added somewhat to the information.
The very best method from the sonic viewpoint is to use an 'L' pad attenuator like I referred to earlier in this thread. This way there is merely one resistor in the signal path at any one time, and only one in shunt to ground.
I bought all the parts from Audio Synthesis in about '95, and they use all Vishays (you like these BFs, I know) and massive military style coin-silver contact Shallco switches, with 31 steps.
For two mono attenuators it cost me over £500 for the parts alone, way back then!
There really is nothing to touch these, as Martin Colloms has said many times, even recently, and they still outperform my passive Audio Synthesis 'Passion Ultimate' (like your pal's) which is nearly as good, but because of its being a remote-operated job (very much more convenient!), the quality of switching in the 'Passion Ultimate' is marginally less good. MC is quite right in awarding it a couple of points less than the dual mono manual 'Passion'.
My previous best, having tried all of the usual Panasonic, Noble, Alps, and Sfernice arrangements with law-faking resistors (like HH favours) was a Penny & Giles pot with Vishay 'law-fakers', but that pot cost over £90 about 15 years ago. This was very slightly better, if anything, than an 'L' pad made of all Holcos, which I also tried at one time.
The only attenuator which might be marginally better would be if the Vishays (or similar bulk-foils) had been surface-mount jobs, thus avoiding the (very short) leads, and I do believe that Jonathan Carr uses this arrangement in his Connoisseurs.
Once heard, never forgotten comes to mind!
Regards,
Bob:
The resistors that I use are both surface-mount and nude - that is, they have neither leads nor protective package. There is only a ceramic substrate, the resistive element, two tiny solder pads, and a thin coat of lacquer to stop short-circuits and environmental elements from touching the resistive element. Compared to the so-called "nude" Texas Components TX2352, the overall construction is far flimsier, and the amount of physical protection provided for the resistive element is far less.
The result is a resistor that sounds good, yes, but also one that is much easier to break than any other resistor that I have ever tried. I always have an excess of each value made, as I know from experience that some will inevitably break during the production process.
regards, jonathan carr
The resistors that I use are both surface-mount and nude - that is, they have neither leads nor protective package. There is only a ceramic substrate, the resistive element, two tiny solder pads, and a thin coat of lacquer to stop short-circuits and environmental elements from touching the resistive element. Compared to the so-called "nude" Texas Components TX2352, the overall construction is far flimsier, and the amount of physical protection provided for the resistive element is far less.
The result is a resistor that sounds good, yes, but also one that is much easier to break than any other resistor that I have ever tried. I always have an excess of each value made, as I know from experience that some will inevitably break during the production process.
regards, jonathan carr
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