Questions regarding topping spec-sheet (voltage and gain)

[ProtestTheHero04]

Hey guys,

I recently bought some used Beyerdynamic T1.2 (600 ohm, 102 db/mW) and I am very interested in the Topping L30 (btw is it true, that it is actually the single ended version of the A90?).

When I read the spec-sheet, there was one thing I wondered about: Output Level. It is 26 Volt peak to peak for all gains (see attachment). Aren't the gain switches usually there to increase/decrese voltage? The current stays always the same, right? Or is it a current switch in this case?

The A90 for example switches Voltage Levels from low to mid/high (see attachment).

Or am I mixing things here? I know that high impedance headphones usually want more Voltage output, will the L30 be sufficient?

I hope the questions are clear...

Best regards

 

[maverickronin]

Gain is relative to the input. If your source is at high enough a voltage you can get maximum current and/or voltage out of the amp. The gain settings are for matching your source's level and headphone's sensitivity to something that gives you a useful range on the volume control.

The L30 has plenty of voltage swing for theT1's.

 

[AnalogSteph]

"Output Level" should have been called "Maximum Output Level", as that's what it is - the physical limit. We'll call this V_out,lim. 26 Vpp ~= 9.2 Vrms is a typical value for equipment with +/-15 V supplies.

Short of this limit, the relation between input and output voltage is linear:
V_out = V_in * G_v * α_pot
with
G_v = amplifier voltage gain,
α_pot = volume pot attenuation

The maximum possible (undistorted) V_out thus is given by the minimum of

• V_in * G_v and
• V_out,lim.

The maximum of G_v for the L30 is +9.5 dB, which is a factor of 3. You are thus going to get 6 Vrms out with a 2 Vrms DAC, still short of the V_out,lim ~= 9.2 Vrms limit but not terribly far off. Since these Tesla Beyers are no less sensitive than common 250/300 ohm models, that should be plenty of output.

Amplifiers like these are voltage sources to a good approximation. Output current will be determined by the ratio of output voltage and load impedance (think Ohm's Law). Current has a limit of its own which tends to determine maximum output into low-impedance loads.

 

[ProtestTheHero04]

"Output Level" should have been called "Maximum Output Level", as that's what it is - the physical limit. We'll call this V_out,lim. 26 Vpp ~= 9.2 Vrms is a typical value for equipment with +/-15 V supplies.

Short of this limit, the relation between input and output voltage is linear:
V_out = V_in * G_v * α_pot
with
G_v = amplifier voltage gain,
α_pot = volume pot attenuation

The maximum possible (undistorted) V_out thus is given by the minimum of

• V_in * G_v and
• V_out,lim.

The maximum of G_v for the L30 is +9.5 dB, which is a factor of 3. You are thus going to get 6 Vrms out with a 2 Vrms DAC, still short of the V_out,lim ~= 9.2 Vrms limit but not terribly far off. Since these Tesla Beyers are no less sensitive than common 250/300 ohm models, that should be plenty of output.

Amplifiers like these are voltage sources to a good approximation. Output current will be determined by the ratio of output voltage and load impedance (think Ohm's Law). Current has a limit of its own which tends to determine maximum output into low-impedance loads.

Well this makes a lot of sense. Thank you for clarifying!

 

[solderdude]

L30 connected to 2V source will allow 115dB peaks with T1 in High gain setting (+9dB)
That's about 100dB average which is very loud.

 

[Ttanik]

L30 connected to 2V source will allow 115dB peaks with T1 in High gain setting (+9dB)
That's about 100dB average which is very loud.

Sorry for digging this thread but I think it's better than recreating a new one with a similar question

Solderdude, would you think the headphone amp from Topping Dx3 pro would keep the Beyer t1 Gen 2 from its highest potential?

Here are its specs :

Thank you very much
Best regards

 

[solderdude]

Dx3 Pro has 2V out DAC and +9dB gain.
This will be the same as E30/L30 combo (also 2V DAC and +9dB gain)

Acc. to Amir's measurements the Dx3 pro reaches 61mW in 600ohm and the L30 reaches 56mW in 600ohm (0.4dB difference)

 

[Ttanik]

Dx3 Pro has 2V out DAC and +9dB gain.
This will be the same as E30/L30 combo (also 2V DAC and +9dB gain)

Acc. to Amir's measurements the Dx3 pro reaches 61mW in 600ohm and the L30 reaches 56mW in 600ohm (0.4dB difference)

Thank you very much! I bought the dx3 only (got it used, the guy strangely had it paired with l30 instead of the usual combo stack).

Best regards!