Low bass pressure is not a special transformer issue. I run an amp with: volume transformer-20AM tube- interstage- VT-25 tube- interstage-AD1 tube- output transformer
So 4 transformers in a row, but the bass is awesome.....
So maybe its an impedance issue or the cinemags have a bass problem.
Correct loading of a transformer is important for its response.
Regards,
So 4 transformers in a row, but the bass is awesome.....
So maybe its an impedance issue or the cinemags have a bass problem.
Correct loading of a transformer is important for its response.
Regards,
Looking a little bit deeper into the documentation it says that the load for one board is 133 ohms. I suppose that means that you have to load the secondary with 2,2K.
The load is the secondary resistor on the trafo parallel to the input impedance of the following stage. Lets say that is 50K we are around 2,4K.
It is easy to test: Just piggyback the 10K resistor with a 3.3K and let us hear what you think.
The load is the secondary resistor on the trafo parallel to the input impedance of the following stage. Lets say that is 50K we are around 2,4K.
It is easy to test: Just piggyback the 10K resistor with a 3.3K and let us hear what you think.
I hope you will succeed.
I did a lot of experiments years ago, with Sowter 1:1 transformers, balanced in - unbalanced out, but I am afraid I do not remember much, just that I found a solution that sounded good on an AD1865 DAC with a tubestage following the transformer. And that the sound changed a lot with different loads. A wrong loaded trafo have peaks and does ring, sometimes a lot.
It is also possible to do the IV conversion directly in the trafo, without any primary load transistors, in that some of the small trafos have around the right resistance in the input coil itself. I think that was what Audio Note did on their most expensive DACs.
I experimented with a 3575Z 10K:10K and a 3603Z 600:600 both of which I still have.
I also used a Lundahl 1676? step up transformer, which sound good as IV converter with 10K on the secondary winding.
But transformers can be tricky to work with for sure.
I did a lot of experiments years ago, with Sowter 1:1 transformers, balanced in - unbalanced out, but I am afraid I do not remember much, just that I found a solution that sounded good on an AD1865 DAC with a tubestage following the transformer. And that the sound changed a lot with different loads. A wrong loaded trafo have peaks and does ring, sometimes a lot.
It is also possible to do the IV conversion directly in the trafo, without any primary load transistors, in that some of the small trafos have around the right resistance in the input coil itself. I think that was what Audio Note did on their most expensive DACs.
I experimented with a 3575Z 10K:10K and a 3603Z 600:600 both of which I still have.
I also used a Lundahl 1676? step up transformer, which sound good as IV converter with 10K on the secondary winding.
But transformers can be tricky to work with for sure.
If anyone are interested I just measured the DC resistance of the 2 types of Sowter transformers. The Z means special good wire. They can be connected both ways, so it is difficult to name a primary and secondary:
Sowter 3603z: phase to CT ~ 35.5 ohms both sides, other side ~ 71.5 ohms.
Sowter 3575z: phase to CT ~ 278/391 ohms, other side ~ 664 ohms
( the unbalance on the CT were similar on both transformers measured)
I happend to use the 3603z on my AD1865A project and it seems that I connected 220 ohms across the 2 CT windings as IV resistors, and nothing on the other side, but my documentaion and memory is weak
Sowter 3603z: phase to CT ~ 35.5 ohms both sides, other side ~ 71.5 ohms.
Sowter 3575z: phase to CT ~ 278/391 ohms, other side ~ 664 ohms
( the unbalance on the CT were similar on both transformers measured)
I happend to use the 3603z on my AD1865A project and it seems that I connected 220 ohms across the 2 CT windings as IV resistors, and nothing on the other side, but my documentaion and memory is weak
and now they are magnetized hence performance in THD and max output is impacted. we warned this before in the thread NOt to do this.
also! can we reduce the amount of transformer posts? I see to much half science in the post to be really of help for the DDDAC output
few points from my side.
bass reach has only to do with the combination of output impedance which must be low, in combination with the input inductance. the latter must be high. if you make it too high, you need lots of windings, making the transformer less transparent en impacted in high frequencies. also more prone for DC magnetizing.
never attach the common tap from the dac to a center tap of the transformer. only pos and neg terminal.
secondary load must me hight as, the dac has a load already.
the sowters which were made on my request (I know they are expensive... ) are specially designed, so they are NOT sensible for the rest DC bias which you will have from the dddac. secondly, it was designed for high output, low distortion ( as long as you do not put DC on it) and high frequency response.
this is always a compromise and my Sowters only bloom to full performance when driven by low enough impedance. Hence the four board recommendation.
believe me, on transformers, we can write till the end of time
for the DDDAC enormous care must be taken to the right things. without explicate knowledge on transformers, you can only be lucky to get a good result. or better, just follow what has been proven to work
also! can we reduce the amount of transformer posts? I see to much half science in the post to be really of help for the DDDAC output
few points from my side.
bass reach has only to do with the combination of output impedance which must be low, in combination with the input inductance. the latter must be high. if you make it too high, you need lots of windings, making the transformer less transparent en impacted in high frequencies. also more prone for DC magnetizing.
never attach the common tap from the dac to a center tap of the transformer. only pos and neg terminal.
secondary load must me hight as, the dac has a load already.
the sowters which were made on my request (I know they are expensive... ) are specially designed, so they are NOT sensible for the rest DC bias which you will have from the dddac. secondly, it was designed for high output, low distortion ( as long as you do not put DC on it) and high frequency response.
this is always a compromise and my Sowters only bloom to full performance when driven by low enough impedance. Hence the four board recommendation.
believe me, on transformers, we can write till the end of time
for the DDDAC enormous care must be taken to the right things. without explicate knowledge on transformers, you can only be lucky to get a good result. or better, just follow what has been proven to work
sorry if you feel insulted, that was never the idea. the half scientific was not personal.
I always try to help and every one who consulted me can confirm that. I wanted to avoid, that too many mixed messages in such short time are causing confusion or put the DIY on the wrong foot. That was all, again sorry if the message did not cross.
I always try to help and every one who consulted me can confirm that. I wanted to avoid, that too many mixed messages in such short time are causing confusion or put the DIY on the wrong foot. That was all, again sorry if the message did not cross.
Please keep us posted!FRESH NEWS: today the PCBs with SMD assembled parts arrived, so I can start with the new prototypes with SPDIF Input...
to be cont'd
Shall put forward an order for 8-stack with pair of Sowters once this switchable USB/SPDIF is available!
Good point. Indeed I was busy with that the past few days. The first setup with one board was very successful. Of course one board to start, as first focus was on spdif functionality. I was very glad ( every one who designed new boards from data sheets and own ideas, knows switching it on the first time is very exciting ) it worked seamlessly the first time. I tested 44.1 up to 192khz spdif. Nice function is, that during music playing on PC and through spdif source, you can just switch between the two sources without any hick up or need to reset anything. Next step is to see how it works with four and eight boards. planned for this weekend, will keep you guys posted
) it worked seamlessly the first time. I tested 44.1 up to 192khz spdif. Nice function is, that during music playing on PC and through spdif source, you can just switch between the two sources without any hick up or need to reset anything. Next step is to see how it works with four and eight boards. planned for this weekend, will keep you guys posted Hope you will post comparison results! I am really curious, as I own a AN kits DAC4.1 (and a few others...) and I am looking with great interest at Doede's DAC. I am sure the DDDAC will perform really well.