Hi Hanze,
Of course, it's aDIY forum 🙂 18R or 25R (for 2xTDA1541A) to Jensen MC 1:8 (configurable 1:4) to choke loaded 46. Pls take a look at the attachment to my previous post. The output impedance of the tube is quite high but my amp can take it with 50k input impedance and short (<1m) cables in between.
That's interesting, thanks for suggesting. Tube needs about -8V bias, with 4mA DC from 2xTDA1541 would mean 2k I/V?? PLus the gain is only about 5. I guess not with this tube.
Thanks again HK!
Of course, it's aDIY forum 🙂 18R or 25R (for 2xTDA1541A) to Jensen MC 1:8 (configurable 1:4) to choke loaded 46. Pls take a look at the attachment to my previous post. The output impedance of the tube is quite high but my amp can take it with 50k input impedance and short (<1m) cables in between.
That's interesting, thanks for suggesting. Tube needs about -8V bias, with 4mA DC from 2xTDA1541 would mean 2k I/V?? PLus the gain is only about 5. I guess not with this tube.
Thanks again HK!
Hey Diyiggy,
Well I played around with some film caps though not of such high values but I just did not like what I heard but when I tested the line output transformer it was a different world all together. You hear everything in the music & it comes through very naturally no etching sound or whatsoever. As to how I get the bass from, it's my self developed recipe.
Im unsure why but many diyers just think that stepping up the voltage using using a trafo will do a good job. 2 crucial points on hand here, output impedance of the trafo & to me most important current drive. Without enough current music will just sound un-dynamic.
Cheers
Well I played around with some film caps though not of such high values but I just did not like what I heard but when I tested the line output transformer it was a different world all together. You hear everything in the music & it comes through very naturally no etching sound or whatsoever. As to how I get the bass from, it's my self developed recipe.
Im unsure why but many diyers just think that stepping up the voltage using using a trafo will do a good job. 2 crucial points on hand here, output impedance of the trafo & to me most important current drive. Without enough current music will just sound un-dynamic.
Cheers
@ Phixphi
In your attachment I would place the I/V resistor on the secondary (properly scaled with the transformer turns ratio). In my experience this works better and I would make part of the 39K adjustable.
In your attachment I would place the I/V resistor on the secondary (properly scaled with the transformer turns ratio). In my experience this works better and I would make part of the 39K adjustable.
When I build & finish my still learning Horn speakers ya but you have to pay for shipping. 😉 Not much between us both itchy finger guys that we've not tested ya. Lol
I have to improve my swim in order to avoid the planes, boats, trains or put my bath tube on the sea and construct a diy wind... then maybe I could take it back, lol ! Long road from Europe than your country side guys, long time I didn't went there and it should last because this 5 microns monster ! (bass and snap, I told you, it's about C5&C6 and gnd behavior...this chip is very special with its three V rails 😉 )
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I've develop my own recipe even better then C5 & 6 ya . Lol
When Covid is cleared I send you the line trafo to play with Iggy
When Covid is cleared I send you the line trafo to play with Iggy
Oh thank you so much... we will speak again about that then. Situation is complicate in my life for the moment and I don't see windows yet.
@ diyiggy: yes and same to you, my regards to Leia.
@ sumotan: yes too much hassle, all of it 🙂
@ phixphi: yes, needs tube that is happy to bias near 0V and with higher gain. I like your approach, I bet it sounds great.
HK
@ sumotan: yes too much hassle, all of it 🙂
@ phixphi: yes, needs tube that is happy to bias near 0V and with higher gain. I like your approach, I bet it sounds great.
HK
Hi Hanz
If one uses a step up trafo at the I/V stage output impedance would be high & after that you add a tube stage which would have to have high RP right ?
So why not use just passive I/V into tube stage & output via opt, that way you kill two birds with 1 stone not needing a signal cap there & reducing output impedance as well.
Yep thats what I like to do, too. Mu 70 Rp 2k2 33R I/V 2:1 OPT.
But there are other ways and certainly interesting method with type 46 as per the other poster, and if driving 50k input impedance, Rp 2 to 3k is no problem.
HK
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Hi Hanze
I experimented with passive moons back though not with opt.
If you're going 2 stage trafo you might have to go parallel TDA
to get better dynamics 1 TDA too polite.
I experimented with passive moons back though not with opt.
If you're going 2 stage trafo you might have to go parallel TDA
to get better dynamics 1 TDA too polite.
Hi Sumotan,
Unsure what you mean, I use direct -2mADC offset through 33R I/V to bias grid of mu 70 triode (p), Rk 10R, Ip 15mA, Rp 2k2, plate load 45H 2:1 OPT.
If I didnt need a low output impedance 1:1 would be very much my preference.
You can add more pieces if you want, I dont mind 🙂
HK
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To sink the unbalanced current, there must be a DC path from the chip output to...somewhere 😀 ... if I understand correctly to +5V. That's why I'm not sure how to implement @ecdesign idea of sinking 2mA to tube's B+. There must be a return path to the chip somewhere. In my case tube and DAC are galvanically separated by the OT. Secondary loading vs. primary loading the OT is a subject on its own. With my MC cartridges I prefer primary loading. Some great info here: :: View topic - SUT Selection The experimentation will show but I think my OT wants to see a well defined driving impedance to preform best.
@diyiggy
Yes, I know Pedja's PDF. Apart from two led lights that I don't think I need, his implementation of 8414 differs from the datasheet only in a 3.3nF cap shorting the RC filter circuit. And a bit changed RC values.
@sumotan
Transformers are good on paper but v difficult to make them right in real life. Each introduces apart from nonlinear also phase errors. I went for LC coupled tube with a massive (compared to the tube Rp) choke and a cap as easier solution.
@Hanze thanks 🙂 What is yuor tube if I may ask?
@ Hanze sorry miss understood your post, noted
@ phixphi For now I'm using 600:600 ohm line out on my AyA dac makes a world of difference in SQ when compared to caps. Hope to test out a wacky tube solution in a couple of months time. Good thing about the trafo that I have is that it can handle 60 ma of dc offset.
@ phixphi For now I'm using 600:600 ohm line out on my AyA dac makes a world of difference in SQ when compared to caps. Hope to test out a wacky tube solution in a couple of months time. Good thing about the trafo that I have is that it can handle 60 ma of dc offset.
You sink the 2 mA from the chip through a resistor to 155V. So actually this resistor should not be 39 Kohm , if you move the I/V resistor to the secondary side of the transformator but 77,5 Kohm. I would make it 75 Kohm resistor and a 10 Kohm trimmer in series.
Hi,
When you say in serie, where exactly ( shem. Perhaps ?). 1:? traffo have you, please. Not I would tube mine because it s above my head than tubes world but just for clarification for non specialists please 🙂
When you say in serie, where exactly ( shem. Perhaps ?). 1:? traffo have you, please. Not I would tube mine because it s above my head than tubes world but just for clarification for non specialists please 🙂
I sink 4mA (2xTDA1541), but actually I think what I drew is not sinking anything since there is no connection from +155V supply to the chip. It must not be what John had in mind. The DC unbalanced current must have a path back to the chip. I think to +5V, the experts pls correct me if I'm wrong.
@sumotan What caps did you use? They are a b*tch. I've spend on the caps and the choke same as for a pair of good outputs...
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If the two grounds are not connected, you are right. No sinking anywhere.
You can use the +5V (and a 1,25 Kohm resistor ) or any other positive supply with ground common to the chip (and of course a properly scaled resistor)