How much high level exists below 40Hz?

[ruffrecords]

Is there a reason the output transformers can't be off board the module itself?

Only space and weight. The Carnhills weigh a pound; the OEPs weigh less than a quarter of that. 12 Cartnills mounted in the back of an 8 into 2 mixer is a lot of heavy steel. It is interesting to note that when Neve first moved from its 50mm wide modules (with internal output transformers) to 35mm modules, they had to fit the output transformers externally. I cannot rememeber what happened subsequently but some time after that the AIR consoles appeared with their (internal) toroidal output transformers.

Cheers

Ian

 

[ruffrecords]

What matters IMO is that the xfmr should not be allowed to distort grossly when driven with sub-40Hz. The usual practice is to band-limit before, usin active filtering for optimized response. Are you ready to sacrifice one tube section for that? Or maybe you could use some negative-impedance drive? I used negative impedance to decrease THD from 2% to 0.1% at 20Hz.

I agree but it depends on your definition of grossly. Bear in mind the measurements I made are at +16dBm into a 600 ohm load. Most times the stage will be much more lightly loaded and the level will be 12dB lower.

Cheers

Ian

 

[abbey road d enfer]

I agree but it depends on your definition of grossly.

Farting out! 

Bear in mind the measurements I made are at +16dBm into a 600 ohm load. Most times the stage will be much more lightly loaded

Load has almost no effect on magnetization (within limits)

and the level will be 12dB lower.

Then what is the distortion at +4dBu output @ 20Hz?

 

[abbey road d enfer]

Not sure how these combined Nickel/Steel cores work. does the Nickel saturate first followed by the steel?

No. the idea is to split the flux according to the saturation limit of each material. Since that of Fe is about 4times that of Ni, a proportion of 1 to 4, aka 80:20 makes sense. So they both arrive at saturation at the same time (if not they would distort badly), with the advantage of having the softer Ni B/H curve at moderate level and less Barkhausen effect.

 

[Bo Deadly]

You are right. Not sure how these combined Nickel/Steel cores work. does the Nickel saturate first followed by the steel?

My understanding is that high Nickel provides lower distortion at all frequencies and particularly at low frequencies. However, it saturates more easily. So as long as you keep the level within the specified limit, it will be lower distortion.

 

[ruffrecords]

No. the idea is to split the flux according to the saturation limit of each material. Since that of Fe is about 4times that of Ni, a proportion of 1 to 4, aka 80:20 makes sense. So they both arrive at saturation at the same time (if not they would distort badly), with the advantage of having the softer Ni B/H curve at moderate level and less Barkhausen effect.

So the idea is the flux density is the same in both.

What does a softer B/H curve mean in this context?

Cheers

ian

 

[abbey road d enfer]

What does a softer B/H curve mean in this context?

More linear at moderate level so less THD, also less "granular"since magnetic domain reorientation takes less energy.

 

[mjrippe]

Only space and weight. The Carnhills weigh a pound; the OEPs weigh less than a quarter of that. 12 Cartnills mounted in the back of an 8 into 2 mixer is a lot of heavy steel. It is interesting to note that when Neve first moved from its 50mm wide modules (with internal output transformers) to 35mm modules, they had to fit the output transformers externally. I cannot rememeber what happened subsequently but some time after that the AIR consoles appeared with their (internal) toroidal output transformers.

Not to sidetrack from your original question, but more for historical purposes: I don't know what the first 35mm Neve modules were, but the 53 series definitely has internal output transformers (non-torroidal).  Also I have a couple 3104 modules which are 1.25" or 31.75mm and they have Marinairs inside.  I have not tested the THD at 20Hz though  ;D

 

[ruffrecords]

Not to sidetrack from your original question, but more for historical purposes: I don't know what the first 35mm Neve modules were, but the 53 series definitely has internal output transformers (non-torroidal).  Also I have a couple 3104 modules which are 1.25" or 31.75mm and they have Marinairs inside.  I have not tested the THD at 20Hz though  ;D

I don't suppose you could post me a pic of the internals showing the transformers??? Can you see the part numbers of the output transformers?

Cheers

Ian

 

[mjrippe]

I don't suppose you could post me a pic of the internals showing the transformers??? Can you see the part numbers of the output transformers?

Cheers

Ian

Sending you an email to avoid going completely off topic.

 

[ruffrecords]

Sending you an email to avoid going completely off topic.

Much appreciated.

Cheers

Ian

 

[CJ]

OT can someone tell me what low freq we have on this track at 5 minutes and beyond?  sounds like a low B (31 Hz)

https://www.youtube.com/watch?v=Y07ujKCDGGM

you need something on an EI 50  steel core  .75" fat stack laced 1 x 1

  about 19.2 Henries for 10 Hz operation, , 30 mH leakage for 25 K Hz,  2.4K : 600  no DC.  this is a cap fed circuit, right?

730 turns pri = 19.2 Henries    sec turns = 365

13.8  K Gauss at 10 Hz.  MLT - 2.2" x 730 = 22 ohms DCR with #32 awg

core height is 1.25" = 31.75 mm plus bracket. (upright mtg)


looks like 32 fits taking half the winding area, so #35 for the secondary leaves room for insulation, wind pri-sec-pri  going to check real world inductance at 10 Hz...

 

[CJ]

well we only had a  1/2" x 5/8" instead of 3/4" bobbin, so we are good for 15 Hz instead of 10, but that's why we over design JIC, 15 aint bad, 10  hz starts to suck current,  you could add more turns to get to 10 Hz but DCR creeps up with #33 wire,

10 v-ac/.00538 amps ac = 1859 ohms reactance at 15  hz ,

1859/ (2 pi x 15 hz) = 1859 /  94.2 = 19.73 Henries pri ind.

DCR came out to 30 ohms,  so this coil/core will work and fit in the rack, ask Sowter how much to wind.
  we used 750 turns instead of 730 to make up a bit for the 1/8" missing from the core with the 5/8" bobbin,

so wind  375T #32  1/2 pri ----375 T #36  sec -----375 T #32 1/2 pri  on 5/8" stack of 50 EI .

max permeability at 15 Hz = 12,000  , not bad for .014" gr or. silicon steel

we will try this tomorrow and see what the freq response does at the hi end,

 

[scott2000]

OT can someone tell me what low freq we have on this track at 5 minutes and beyond?  sounds like a low B (31 Hz)
watch?v=Y07ujKCDGGM

https://www.youtube.com/

Looks like it....tippy top cents of B and C 32hz




I keep hearing the kick distort in this techno track (easier to hear in the beginning like 10seconds)???.......... I think it may be my headphones??? anyone else hear it this way?? I need new headphones or wiring if so........ it has a lot of low end for a techno track...

https://www.youtube.com/watch?time_continue=5&v=rUm3rl7-1N8

 

[kambo]

Cleanliness on lowest piano or organ notes, it'll matter.

+1
for the sound design work i do,
lo end needs to be pretty damn clean...

 

[abbey road d enfer]

I keep hearing the kick distort in this techno track (easier to hear in the beginning like 10seconds)???

I don't hear it distort, but surely the constant low rumble is very annoying.
What annoys me also is the number of saturation plug-ins and their plethoric use on many tracks today; some of them tracks could be really nice if they didn't have this permanent dose of non-musical harmonics.

 

[walter]

It is close. The space available between the PCB and the top steel screen is 27mm so we are about 5mm short.

Cheers

Ian

Could the transformer fit inside the chassis with a hole cut in the pcb to accommodate?

 

[ruffrecords]

Could the transformer fit inside the chassis with a hole cut in the pcb to accommodate?

Not quite. The top of the PCB is 3.87mm from the left edge of the front panel so making a hole in the PCB might gain us nearly 4mm which still leaves us 1mm short. I don't want to make a hole in the steel shield because one of its jobs is to magnetically isolate output transformers in adjacent modules. Without it they will talk to each other.

Cheers

Ian

 

[CJ]

finished the transformer, it is flat from 15 Hz to 400 K Hz, 

fits vertically in  1U rack, 

still had room for more wire so 800 turns pri and 400 sec will fit to get down to 10 Hz,

DCR was pri = 29  and sec =  38 ohms,

sq wave tests, 10 K Hz and 100 K Hz>

 

[Tubetec]

10hz-400 khz wow .
I might need to roll up some of those for myself ,
;D