so you think it would make sense to use the transformer in 1:20 and just take a wirewrap wire which would give me around 0,25R with a lenght of about 2,5"?
at least the transformer was made for voltages like this
cheers,klaus
My S&B 1:20 works very well, you have more output and still reasonably low output impedance. I take a thin copper or silver wire (see my post above). About 25cm of a 0.07 wire makes a resistance of about 1Ohm. Exact lenght is not important, but both wires must measure exactly the same, must have an exact mid point, measure with a ruler. The thinner the wire, the better the sound.
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I'll probably be looking at 2,2R from each phase to gnd, and then put a LL9226 afterwards in 1:20 mode, transformer would have internal DCR of 1:260R, so with this config i'll have an output impedance of approx 2K, which sounds reasonable. According to Lundahl this transformer does work with up to 40mV on the primary.
A 1:25 would be even better for me, but i haven't found anybody that does have any AM-transformer with such low internal resistance as these Lundahls. The LL1943 would probably also work in 1:32 but would yield much higher output R, since the impedance ratio would be 1:1024.
A 1:25 would be even better for me, but i haven't found anybody that does have any AM-transformer with such low internal resistance as these Lundahls. The LL1943 would probably also work in 1:32 but would yield much higher output R, since the impedance ratio would be 1:1024.
Have ANYBODY tried running dual mono Buffalo/ES9018's with step-up transformers?
I'm thinking this would be the best of two worlds. since you would have approx 32mA per channel it would be possible to load each phase <1R, and since the output impedance would be so low, it would be possible to run 1:32 transformer.
With output loaded with 0,9R on each phase, and with LL1941 i calculated output impedance of approx 2460R. With ~0,92V on the secondary. and since i myself have 3,75x gain thereafter, i would get approx 2,4vRMS out thereafter. It would even be possible to run even lower loading.
So - have anybody tried anything similar this?
I'm thinking this would be the best of two worlds. since you would have approx 32mA per channel it would be possible to load each phase <1R, and since the output impedance would be so low, it would be possible to run 1:32 transformer.
With output loaded with 0,9R on each phase, and with LL1941 i calculated output impedance of approx 2460R. With ~0,92V on the secondary. and since i myself have 3,75x gain thereafter, i would get approx 2,4vRMS out thereafter. It would even be possible to run even lower loading.
So - have anybody tried anything similar this?
this is exactly my plan! i have a second buff IIIse at home and will try it soon. but at first i want to fine-tune my tube output stage, modified it last weekend. playing right now: I/V resistor 1R tx2352(no tx2575 with low values like this:-( , s&b tx 103 stepup 1:5, choke loaded 5842. at first with 100r cathode resistor, 135v on the plate, unbypassed. now i have a battery in series with the grid, cathode directly to ground. clearly better, but i will play a little with the voltages. 10k on the input of the 5842 is also a little high i think, will get a pot and set it when i run dual mono. in dual mono i will put a second 1R resistor in parallel. in my system i could decrease this value even further....vitavox horns...
I take it you already have the transformer, otherwise - wouldn't it be better getting a transformer with lower internal impedance, since the primary is 17ohms , you could load the dac even lower (0,5R?) with another transformer. LL9226 seems like a candidate for you, if running in 1:20 you get approx 1,25R primary. But then again, if you already have a transformer, try it!
Also, please let me know how it sounds for you, because i'm really interested to hear
EDIT: i see S&B transformer is possible to run in 1:10 and 1:20 also, why not try that and lower load?
Also, please let me know how it sounds for you, because i'm really interested to hear
EDIT: i see S&B transformer is possible to run in 1:10 and 1:20 also, why not try that and lower load?
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right now i run it with 1R in 1:5. sounds extremly good(secondary on the stepup is 10k, a little bit to high, played around with a pot,i think around 9k would be ok. but hard to say if you compare the tx2575 10k with a pot.will decide when it is dual mono.)...but there is always room for improvement
dual mono i will run it with 0,5R.
i also thought about 1:20, 0,125R on the primary. like a low output mc cartridge(the voltage). would i be worth it?
i plan do make a small pcb for connecting the buff to dual mono(soldered to the bottom), 0,125R should be possible without resistor(pcb will be around 25x 90mm, space for resistors and connecting stepup.)
what i dont know: noise pickup? double layer? ground plane? and what is the tolerance of a resistor etched on a pcb? is there a point of dimishing results?
i think it would be possible to make a pcb with 2 0,125R resistors but....my budget is limited
anyway, i will get another set of plate chokes this week(lundahl 1667, 270H, 15ma, my bartoluccis are only 80H), will try this first. i want a perfect tube output before i go dual mono.
cheers,klaus
dual mono i will run it with 0,5R.
i also thought about 1:20, 0,125R on the primary. like a low output mc cartridge(the voltage). would i be worth it?
i plan do make a small pcb for connecting the buff to dual mono(soldered to the bottom), 0,125R should be possible without resistor(pcb will be around 25x 90mm, space for resistors and connecting stepup.)
what i dont know: noise pickup? double layer? ground plane? and what is the tolerance of a resistor etched on a pcb? is there a point of dimishing results?
i think it would be possible to make a pcb with 2 0,125R resistors but....my budget is limited
anyway, i will get another set of plate chokes this week(lundahl 1667, 270H, 15ma, my bartoluccis are only 80H), will try this first. i want a perfect tube output before i go dual mono.
cheers,klaus
Have you tried with cascode DN2540's instead of plate choke? of course you'll need a little higher (not much) B+, but it will give you very nice PSRR, and channel separation.
Many perfer it to choke loading.
Are you running SE or BAL tube output-stage? have Balanced line-stage/power amp after, so i will run balanced all the way. Myself i will need to buy a quite high step-up ratio, since i have 6h30p-dr tubes in the line stage (mu=15) and then output transformer wired in 8:1 (to not have to much gain from the analogue inputs.)
Well, you could always try many different ways of connecting the transformer 1:5/1:10/1:20 and report back on results. Even if you have tube-stage thereafter it will still be interesting to hear your reports with really low loading and high step-up ratio. I'm most interested to hear what you think about dual-mono and 1:20 step-up
Many perfer it to choke loading.
Are you running SE or BAL tube output-stage? have Balanced line-stage/power amp after, so i will run balanced all the way. Myself i will need to buy a quite high step-up ratio, since i have 6h30p-dr tubes in the line stage (mu=15) and then output transformer wired in 8:1 (to not have to much gain from the analogue inputs.)
Well, you could always try many different ways of connecting the transformer 1:5/1:10/1:20 and report back on results. Even if you have tube-stage thereafter it will still be interesting to hear your reports with really low loading and high step-up ratio. I'm most interested to hear what you think about dual-mono and 1:20 step-up
right now i run it with 1R in 1:5. sounds extremly good(secondary on the stepup is 10k, a little bit to high, played around with a pot,i think around 9k would be ok. but hard to say if you compare the tx2575 10k with a pot.will decide when it is dual mono.)...but there is always room for improvement
dual mono i will run it with 0,5R.
i also thought about 1:20, 0,125R on the primary. like a low output mc cartridge(the voltage). would i be worth it?
i plan do make a small pcb for connecting the buff to dual mono(soldered to the bottom), 0,125R should be possible without resistor(pcb will be around 25x 90mm, space for resistors and connecting stepup.)
what i dont know: noise pickup? double layer? ground plane? and what is the tolerance of a resistor etched on a pcb? is there a point of dimishing results?
i think it would be possible to make a pcb with 2 0,125R resistors but....my budget is limited
anyway, i will get another set of plate chokes this week(lundahl 1667, 270H, 15ma, my bartoluccis are only 80H), will try this first. i want a perfect tube output before i go dual mono.
cheers,klaus
Take a piece of wire!
best sound, better than any resistor you can buy!
I have copper at the moment, but will buy silver, if I can get a piece.
hm, i´m a tube guy
i never heard a transistor of any kind sound as good as a tube. does not work for me. its even desturbing in the regulator. right now i run the whole thing with allen wrights super reg. valve rectifier, lclclc sounds better to me. but i ordered the salas hv reg, 2 of them
haha, i sold my phono because i thought i will do the equalisation on my pc....not so shure right now!
the buff with the exa sounds really good, but any dsp .....maybe some years later, right now it does not work for me.
i never heard a transistor of any kind sound as good as a tube. does not work for me. its even desturbing in the regulator. right now i run the whole thing with allen wrights super reg. valve rectifier, lclclc sounds better to me. but i ordered the salas hv reg, 2 of them
haha, i sold my phono because i thought i will do the equalisation on my pc....not so shure right now!
the buff with the exa sounds really good, but any dsp .....maybe some years later, right now it does not work for me.
It is not the best of two worlds:
- With lower input impedance, there is lower output impedance, correct, but useless. If you have an active gain stage with lets say the "official" 47k, there is no benefit of a lower output impedance.
- An important part of this thread is about lowering the resistance seen by the dac, but this is true only if we mean the same amount of parallel dacs. Normally we mean the output of 4 parallel dacs in the Sabre chip. So we should not speak of resistance any more if we change the number of dacs. We should speak of the real important parameter: Output voltage of the parallel dacs in current mode. It should be as low as possible as well, but now we see what happens, if we use a board in mono mode:
Output current is doubled, resistance is divided by 2, output voltage is the same! So in mono mod you must lower the resistance just to keep the same output voltage!
There is only one reason to use 2 chips in mono mode:
Because more dacs are involved, THD is lower, and it sounds better,
but we have yet to ask people, who have done it.
Well of course, i know that the important part is to get the dac-chips in "current-mode" which is why, in dual mono, i will get twice the current (and hence twice the voltage output with same loading). Also, lower output impedance, makes it possible to use higher step-up ratio on transformer without having many K-ohm output impedance.
So why is say "best of two worlds", is because at least on paper - for my application, this would mean that i could lower the loading of dac-output, while i still get lower output impedance from the transformers and at the same time higher output level.
Anyway, will be interesting to see how it sounds for chaos if he tries lower loading with step-ups.
So why is say "best of two worlds", is because at least on paper - for my application, this would mean that i could lower the loading of dac-output, while i still get lower output impedance from the transformers and at the same time higher output level.
Anyway, will be interesting to see how it sounds for chaos if he tries lower loading with step-ups.
Sorry, but you miss the point: If you load the mono dac with the same resistor, the voltage doubles, and that is worse for the sound!
Zero voltage means perfect current mode, full voltage means obviously voltage mode.
I have yet to find the point where current mode audibly worsens,
at the moment I have about 0.55R per side, stereo dac, must be totally around 6mVrms.
And even with a higher step up ratio output res would still be lower than 47k.
I have seen that you have been trying hard to find the best solutions for the Buffalo dac. I am interested to learn, how you use it at the moment, I mean which power supply, transformer and/or active stage.
Sharing experiences is a valuable part of a thread.
I have already posted my implementation above, still no active gain stage at the moment.
@ rolls: silver, copper...there is small difference. i use it for fine-tuning. but right now i wait for my plate chokes...many m of copper
what i dont know, does it make sense to go really low with the value of the I/V resistor? lower than 0,5R? down to 0,125R?
You have a good implementation to experiment with different resistors, because your tube stage has high input resistance, so you could play with different resistors. I can not do this at the moment, because I have no active stage, higher would mean to high on the secondary for the TVC, and lower would mean too low even for the horn. I tried 2.2 Ohm, was not so good, but the reason could have been "leaving current mode" or secondary impedance too high.
If you take thin wire, it costs you nearly nothing, and the sound is still better than even a Texas, and we should grasp the chance to use wire, it is only possible with very low values. Cut a length, fold it in the middle to solder to an earthpoint. If you still want the Texas, you can find the critical point with wire and then buy a Texas. There is just one drawback I noticed even or especially with thin wire: You need at least 20 hours burn in. This would mean soldering very thin wire, playing a CD for 20 hours, listen seriously, ....
Lets solve the big question: where is the border, where does current mode becomes audibly worse?
I have yet to decide to build an active stage after the 1:25 transformer. It sounds extremly smooth yet detailed, in front of me,
without all the artifacts of the mains, regulators.
Nevertheless I could need a bit more power, actually my dac has to drive a transformer, a TVC, 2 interconnects and the power amp, could be too much for the tiny chip.
Well, i didn't think about it that way. So probably the only better thing when running step-up and dual mono is that you could go for a higher step-up ratio with the lower loading of the dac in my case. (to get higher signal level).
Well, i don't own the dac yet - i'm the kind of guy who try to learn before buying.
But i will feed the dac with SSLV1.1, and i'm thinking about getting Ian's FIFO, but not shure about that yet. The problem for me is room, so i'll have to decide between active gain stage or FIFO/reclocker.
All, this will be built into my line-stage case, where i have approx 11,5dB gain - and i would like to have 2.0 - 2.5vRMS out from the line stage.
Well, i don't own the dac yet - i'm the kind of guy who try to learn before buying.
But i will feed the dac with SSLV1.1, and i'm thinking about getting Ian's FIFO, but not shure about that yet. The problem for me is room, so i'll have to decide between active gain stage or FIFO/reclocker.
All, this will be built into my line-stage case, where i have approx 11,5dB gain - and i would like to have 2.0 - 2.5vRMS out from the line stage.
I am with you, but just up to a certain degree. Just have a look at your own list of posts, then you know what I mean. You have been "waiting" for years. Buy a Buffalo, switchboard is not important. When you listen for the first time, you will ask yourself: why didn't I buy it years ago? I still have a 24dB Dac, sounds fantastic with batteries.
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I don't read this thread much, but I did today for some reason. Let's keep it on topic.
I totally agree, verbal arguments are always welcome, thank you.
André
I know where you are coming from. But the Sabre DAC is different from any other DAC, not just that it can be used in both modes - but arguably sounds best in Current mode IMO.
If you go back through the posts, see the ones that discusses the lighter tonal balance of the Sabre DAC is Voltage mode.
If you want to use Voltage, then transformer is the way to go. Many have heard me say that many times over, that with a differential voltage output where any DC offset will not be seen by the Primary of the transformer. But the Sabre DAC is not a conventional Voltage DAC.
The Sabre DAC has a much higher output Z than is usual for a Voltage DAC and hence there is reason to point to it as the cause of the light tonal balance when used as such. We need to reduce that Z and also force the DAC into current.
So, Voltage mode, use:
The two resistors force the Sabre DAC into 3.14mA current offset while reducing offset voltage from 1.65V to about 1V. The output will be 1.3V RMS.
But how could this be applied to using Tubes and Current mode.
Pretty much all the post-DAC Tube designs I have seen avoid full-on Current mode. But with the Sabre DAC there is and opportunity if employing above suggestion repeated here:
We can force the Sabre DAC into Current mode by pulling it virtually down to 0V DC and then get an offset current of 8mA. Using the same 1:1 transformer, it now opens up the way to use Current mode with Tubes.
So the above example shows how it can be done.
The point is that the Sabre DAC has flexibilities in the way that no other DAC has and using it in Plain Vanilla Voltage mode can be avoided as IMO it gives worst performance.
Cheers, Joe R.
hello all
sorry for the silly question .....
but where you found, the resistor 195r, to be used in series with the transformer jensen jt 11 EMCF?
I can not find this value .....
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