[goldwerger]

Does anybody know if there is any problem if I plug in 2 different impedance headphones at the same time?

there shouldn't be a problem, safety wise

when plugging multiple headphoens you will hear volume going down, as same power is used to drive multiple loads (true to prettty much all amps that have multiple ports; unless the amps are genuinely separate for them which is rare).

I do wonder though, technically, what happens to damping when that happens - i.e. whether the output impedance shared across two loads of varying impedances results in any kind of averaging which impacts the damping of each of those, or not at all (i.e. parallel driving without any feedback happening). This question is beyond my knowledge as I am not an electrical engineer - if someone knows and can chime in, would be grateul to learn myself..

meantime, try and find out how it sounds..

 

[carboncopy]

there shouldn't be a problem, safety wise

when plugging multiple headphoens you will hear volume going down, as same power is used to drive multiple loads (true to prettty much all amps that have multiple ports; unless the amps are genuinely separate for them which is rare).

I do wonder though, technically, what happens to damping when that happens - i.e. whether the output impedance shared across two loads of varying impedances results in any kind of averaging which impacts the damping of each of those, or not at all (i.e. parallel driving without any feedback happening). This question is beyond my knowledge as I am not an electrical engineer - if someone knows and can chime in, would be grateul to learn myself..

meantime, try and find out how it sounds..

It is essentially how you wrote. If you connect to 300 Ohms headphones to the amp (assuming it is a parallel connection, which is usually the case), then the sum sinks to 150 Ohm. This then has influence to the damping factor of course.

The complexity of the thing is, that headphones represent an impedance (as every voice coil), not just a resistance. So it has inductivity and capacitance too. These three parameters (resistance, inductivity and capacitance) are the so called impedance. Now, two from these three (capacitance and inductivity) are frequency dependent, meaning they represent different values at different frequencies. And two different voice coils/membrans (say a biocelluid and the BE coadted Verité drivers) has different propertiers accros the frequency. So paralleling them can result some alligment/disalligment situations accross the frequency range.

As for how strong these effects are and whether they are observably for the listener is case-to-case different. But manufacturers know how an impedance curve of a headphone runs and they are part of the voicing. So, mixing together two such curves is always a deviation.

 

[goldwerger]

It is essentially how you wrote. If you connect to 300 Ohms headphones to the amp (assuming it is a parallel connection, which is usually the case), then the sum sinks to 150 Ohm. This then has influence to the damping factor of course.

The complexity of the thing is, that headphones represent an impedance (as every voice coil), not just a resistance. So it has inductivity and capacitance too. These three parameters (resistance, inductivity and capacitance) are the so called impedance. Now, two from these three (capacitance and inductivity) are frequency dependent, meaning they represent different values at different frequencies. And two different voice coils/membrans (say a biocelluid and the BE coadted Verité drivers) has different propertiers accros the frequency. So paralleling them can result some alligment/disalligment situations accross the frequency range.

As for how strong these effects are and whether they are observably for the listener is case-to-case different. But manufacturers know how an impedance curve of a headphone runs and they are part of the voicing. So, mixing together two such curves is always a deviation.

Makes perfect sense! Thanks for the more cogent explanation..!!

 

[OnlySoMany]

Quick question for all you smart people out there:

I am looking at getting a set of Transparent Audio RCA cables to use between the ZMF DECWARE and the Taboo MKIII. Their reference cable series goes off of high impedance and low impedance (HI-Z and LOW-Z). Based on the specs below from the ZMF website, what would this classify as? I assume this would mean the ZMD Decware output would be high impedance, correct?

https://shop.zmfheadphones.com/products/decware-zmf-otl

SPECS:

• 5U4G Rectifier, 6N6P Drivers, 6DJ8/ECC88/6922/6N1P input
• 2 x XLR Jacks, 2 x 1/4" Jacks
• 2 x RCA L/R Inputs
• 1 x RCA Pre-Amp output
• Dual L/R VU Meters
• 49 ohm output impedance
• 450 mW @ 250 ohms

 

[goldwerger]

Quick question for all you smart people out there:

I am looking at getting a set of Transparent Audio RCA cables to use between the ZMF DECWARE and the Taboo MKIII. Their reference cable series goes off of high impedance and low impedance (HI-Z and LOW-Z). Based on the specs below from the ZMF website, what would this classify as? I assume this would mean the ZMD Decware output would be high impedance, correct?

https://shop.zmfheadphones.com/products/decware-zmf-otl

SPECS:

• 5U4G Rectifier, 6N6P Drivers, 6DJ8/ECC88/6922/6N1P input
• 2 x XLR Jacks, 2 x 1/4" Jacks
• 2 x RCA L/R Inputs
• 1 x RCA Pre-Amp output
• Dual L/R VU Meters
• 49 ohm output impedance
• 450 mW @ 250 ohms

The output impedance on the OTL interconnects may or may mot be the same as its headphone outputs, but it does typically run in lower numbers for most integrated amps (something in the 10-100 ohm range)

The input impedance of the Taboo interconnects will typically be high (something like 10k to 100k ohms).

In both cases I’d recommend reaching out to Decware to confirm.

I’m not familiar with Transparent Audio’s RCA cables. Looks like they are meant to be used directionally (not common) and if there is a low vs high impedance ends to match then I’d align them per above - between components, source is always is the low impedance out and destination is high impedance input.

 

[OnlySoMany]

The output impedance on the OTL interconnects may or may mot be the same as its headphone outputs, but it does typically run in lower numbers for most integrated amps (something in the 10-100 ohm range)

The input impedance of the Taboo interconnects will typically be high (something like 10k to 100k ohms).

In both cases I’d recommend reaching out to Decware to confirm.

I’m not familiar with Transparent Audio’s RCA cables. Looks like they are meant to be used directionally (not common) and if there is a low vs high impedance ends to match then I’d align them per above - between components, source is always is the low impedance out and destination is high impedance input.

Thank you. @zach915m Can you possibly provide some input here? When going OUT from the ZMF Decware to the Taboo, what impedance would that be? The high-end Transparent Audio "Reference" cables are usually rated for a high-impedance or low-impedance setup. What would that impedance be in that chain? Is 49ohn considered high or low? Also, on the Taboo, what is that input impedance?


Lumin X1 > ZMF Decware > CABLE GOES HERE > Decware Taboo MKIII



Original post for transparency and reference (pun intended):

I am looking at getting a set of Transparent Audio RCA cables to use between the ZMF DECWARE and the Taboo MKIII. Their reference cable series goes off of high impedance and low impedance (HI-Z and LOW-Z). Based on the specs below from the ZMF website, what would this classify as? I assume this would mean the ZMD Decware output would be high impedance, correct?

https://shop.zmfheadphones.com/products/decware-zmf-otl

SPECS:

• 5U4G Rectifier, 6N6P Drivers, 6DJ8/ECC88/6922/6N1P input
• 2 x XLR Jacks, 2 x 1/4" Jacks
• 2 x RCA L/R Inputs
• 1 x RCA Pre-Amp output
• Dual L/R VU Meters
• 49 ohm output impedance
• 450 mW @ 250 ohms

-------------

Normally I'd just buy a decent RCA cable and not worry about it, but these start at around $4K new, and I found one pretty cheap.

 

[OnlySoMany]

The output impedance on the OTL interconnects may or may mot be the same as its headphone outputs, but it does typically run in lower numbers for most integrated amps (something in the 10-100 ohm range)

The input impedance of the Taboo interconnects will typically be high (something like 10k to 100k ohms).

In both cases I’d recommend reaching out to Decware to confirm.

I’m not familiar with Transparent Audio’s RCA cables. Looks like they are meant to be used directionally (not common) and if there is a low vs high impedance ends to match then I’d align them per above - between components, source is always is the low impedance out and destination is high impedance input.

Thank you for the reply. I just ended up getting another set of Transparent Ultra cables off Audiogon. For now, I'm using my audioquest diamond bnc cables with gold bnc to rca converter ends. Works perfectly for now until next week.

God this amp sounds lovely. True masterpiece. To anyone waiting on a Stratus, Stellaris or OTL otherwise, give this one a listen.

 

[goldwerger]

Thank you for the reply. I just ended up getting another set of Transparent Ultra cables off Audiogon. For now, I'm using my audioquest diamond bnc cables with gold bnc to rca converter ends. Works perfectly for now until next week.

God this amp sounds lovely. True masterpiece. To anyone waiting on a Stratus, Stellaris or OTL otherwise, give this one a listen.

nice....!

 

[OnlySoMany]

 

[NewCanFan]

Is it possible to try a Telefunken G73-r in the input stage or will it damage the amp?

 

[goldwerger]

Is it possible to try a Telefunken G73-r in the input stage or will it damage the amp?

I’ll let the more electrically knowledgeable folks opine on this, but my layman knowledge is that 12au7 types (like the G73-R tube) use 12.6V heater voltage, while the 6DJ8 gain tube types of this OTL use 6.3V heater voltage, so there is an operating point mismatch. The tube pinout is also different. That said, you could get a custom adapter to match the pinout, as well as to use only one of the dual triodes inside a 12au7 tube in order to get only 6.3V. I’m not sure how the tube will then sound performance wise, but it would be electrically feasible with that type of an adapter in theory I think.

 

[NewCanFan]

I’ll let the more electrically knowledgeable folks opine on this, but my layman knowledge is that 12au7 types (like the G73-R tube) use 12.6V heater voltage, while the 6DJ8 gain tube types of this OTL use 6.3V heater voltage, so there is an operating point mismatch. The tube pinout is also different. That said, you could get a custom adapter to match the pinout, as well as to use only one of the dual triodes inside a 12au7 tube in order to get only 6.3V. I’m not sure how the tube will then sound performance wise, but it would be electrically feasible with that type of an adapter in theory I think.

Awesome thank you, I had seen that the g-73r could be 6.3 or 12.6 but no feedback on how to make them compatible. So it might be possible with an adaptor that is specifically wired to just use one of the dual triodes?

 

[ng5921]

Have some hum in the left pre-amp output channel of my ZMF OTL. I've narrowed it down specifically to the left channel pre-amp out. There's a also a very slight hum in the left channel when listening to the amp itself but it is much more subtle than when the OTL is being used as a pre-amp. I've tried swapping the power tubes around and used 2 different sets of tubes, also tried a different rectifier and the problem has not gone away. I've confirmed the Aegis itself has no hum when not being fed by the ZMF OTL.

Has anyone else experienced this? Next step I was going to physically isolate the Decware from my other gear (currently sitting next to the Aegis) when I get a chance.

 

[goldwerger]

Awesome thank you, I had seen that the g-73r could be 6.3 or 12.6 but no feedback on how to make them compatible. So it might be possible with an adaptor that is specifically wired to just use one of the dual triodes?

Yes I believe so. Best to confirm with Decware.

 

[jonathan c]

Awesome thank you, I had seen that the g-73r could be 6.3 or 12.6 but no feedback on how to make them compatible. So it might be possible with an adaptor that is specifically wired to just use one of the dual triodes?

The TFK G-73R is the ultimate 12AU7 tube. A 12AU7 tube may be used in lieu of a 6DJ8 / 6922 / ECC88 tube with the following:

The adapter 'rewires' the tube pins such that voltage and filament current are halved -- to 6.3V and 300mA. [I have used these PTS adapters in: Liquid Platinum, Schiit Mjolnir 2, Schiit Valhalla 2, Woo WA2, Woo WA3 -- to great sonic enjoyment.]