Anyone got diagrams for the TL Audio VTC console please ?

[Kevin Stuke]

Hi Sam,

thanks a lot, you saved the easter audiorepairs

 

[S.Samuelsson]

Hi Kevin,

You're welcome, have fun .

Regards,
Sam

 

[THS-Studio]

Even though this thread is a bit older, there is a plausible explanation why TL-Audio removed the SSM2017 and used a well-known and proven input circuit instead. 1. In the SSM2017 circuit, the LineIn was fed to the "microphone input" via a simple voltage divider (40db 100 times). This is not particularly subtle, as the microphone preamplifier is only limited to 20 kHz for HF safety reasons, while the frequency response otherwise goes up to 40 kHz.
2. The SSM2017 and its successor, the SSM2019, had relatively high failure rates, particularly with long cable lengths, high capacitances built up, which "destroyed" the very sensitive SSM despite limiter diodes... The NE5532 circuit with the 4 input transistors was very robust in comparison...
3. In the new circuit, the Line IN input with 2x NE5532 has a completely separate path, but is sent back to the "microphone main path" before the impact sound filter and Pgase Reserve. Now with reasonable impedance - without voltage divider and cutoff frequency 40kHz. That is serious and much more professional than the SSM 2017 circuit. However, since the company had previously done a big advertising campaign regarding the TOP quality feature of the SSM2017 - but a rather unprofessional Line IN 1:100 attenuation - they had probably quietly corrected this error... Well - unfortunately, the company closed in 2012. Nevertheless, the VTC console is a dream in terms of sound for me personally... I have the 24-channel version and am really happy with it... The first circuit with the SSM2017 came out in 1999 - the revision with the NE5532 in 2003. My console is probably from 2006. There are also strange versions of the power supply. The circuit diagram shows 56,000uF unregulated electrolytic capacitors behind the rectifiers. But in my case it is only 22,000uF in the power supply. I will definitely modify that. My console has a signal-to-noise ratio of around -84 dB with 24 connected channels... That's a great value, slightly overlaid with a residual hum - which could be due to the not low values of the electrolytic capacitors.

 

[Kevin Stuke]

Hi – thanks a lot for the detailed explanation regarding the opamp changes – I definitely feel less bad about them now

Sorry for the late response – I have – fortunately or unfortunately depending on how you look on it been quite busy with the video side of my business as well as live mixing and didn’t get to as much Audio tinkering as I liked. But it is coming along, and I have already done first test recordings.

I may have googled your Studio and found out that we are both in Germany btw. It looks really cool and definitely reminds me of the need to improve my acoustic treatment

Also very interesting info regarding the Power supplies. I’ll definitely look into that. If you are upgrading your power supply anyway it might be worth replacing the fans – mine were extremely loud and since I don´t have a separate tacking room (or a separate audio room for that matter – it has to share the space with photography and video stuff) that was a problem. I´ve installed some much quieter Noctuas and that improved things al lot. I’ve also measured the Thermals to make shure that nothing will overheat – I can share the detailed records if you are interested

Greetings from Göttingen
Kevin

View attachment LR Exp for Web - TL VTC + Mixing Studio 21.08.24 (5 von 184) _MG_4383.jpg
View attachment LR Exp for Web - TL VTC + Mixing Studio 21.08.24 (34 von 184) _MG_4516.jpg

 

[THS-Studio]

Hello Kevin. This is how you get to know each other in this group. Yes - I am the THS studio in Dormagen - I am "75" and have finished my active "recording session drudgery" and am now enjoying my mix and mastering studio. The DIY Fairchild 670, 660 and 66309 and the legendary Sonte1 MPQ 5 are also part of the outboard. The VTC is a dream ... I have worked on many desks in my active time - but here on the VTC it is the most fun and that is also when playing classical music. Regarding the power supply: I already have a very quiet fan installed. No need for a "side room". I have increased the 5 electrolytic capacitors to a total of 82,000 uF. The buzzing noise can only be heard when the volume potentiometer is wide open and there is not the slightest hum of any kind. However, this is also due to the strict star grounding of the entire studio and the separation of all ground connections in the symmetrical inputs and outputs of the console.

 

[jensenmann]

Hi Holger + Kevin
I´ve had very good results with replacing these SSM2017 with That 1510/1512 chips in various consoles. They sound more detailed with less distortion and don´t get as hot as the 2017. In the past I´ve "repaired" a few defective 2017 preamps just by resoldering them. Most likely the heat was responsible for this fault since the solder clearly looked like cold solderspots on a few legs of the 2017 while the others were still ok.
cheers from Karlsruhe

 

[THS-Studio]

Hi Jensenmann " nice to meet you here " The later input circuit / mic line as on my desk has a different layout than the SSM 2017 version and is equipped with an NE5532. I see no need to modify it. The VTC is equipped with NE5532 throughout for good reason...also, as a mixing studio, I don't use the mic inputs and the NE5532 is ideal for line level even after almost 35 years.... ( so i think ...)

 

[Matt Syson]

Quote: The buzzing noise can only be heard when the volume potentiometer is wide open.

I would not be happy with that and it is possibly an issue with the very large capacitances that reduce the average ripple but accentuate the current spikes unless the supply is really well designed.

 

[THS-Studio]

Hi Matt, We may have misunderstood each other. The larger capacities are specified in the service manual, but I didn't have them. The signal-to-noise ratio or the desk noise is -84 dB with 40 channels connected (including B-Mix) and +4 dB nominal level and master fader at zero dB!! That's a fantastic value for an analog desk. In addition, the IC supply voltage is separately stabilized and buffered for each 8-channel unit. So your statement about possible voltage peaks is unclear to me - or rather incomprehensible.

 

[Matt Syson]

Very large capacitance values and low ESR will tend to increase the current spikes because the rectifier diodes act as sharp switches at the point in the AC 'sinewave' where the voltage is higher than that already in the capacitor and this current spike is only limited by winding resistance and the effective 'resistance' of the diodes. Of course if this is happening on a circuit board the current spikes may radiate into adjacent circuit traces and it is easy to make a mess of this so a unit that worked fine with original spec capacitors may now radiate 100/120Hz spikes and harmonics and conduct this into circuit traces that share the same route. This is one place where star wiring is important or at least careful consideration of where this current spike can pollute.