Bottlehead Crack + Beyerdynamic T1 2nd (600ohm) insufficient volume

[Varail]

Hi
I bought a BHC already assembled. My source is IFI Nano Black > BHC > Beyerdynamic T1 2nd (600ohm).
Im not complaining about the quality of the sound but I dont think I have enough volume. My pot starts from 12 and ends at 9 and while is moderately loud is nowhere close to be to much. It does feel like I miss a lot since I
replaced the BHC in the chain with a portable Cayin C5 and Im getting much louder and therefore better sound (that little thing is a beast).

The tube is a  Western Electric 5998/421A.

Any ideas or clues ?

Thank you

[Paul Birkeland]

Can you flip it over and show us what's underneath?

[Varail]

Here it is ..  The sound is really nice so I don't think the device is defective but the fact that I can maximize the volume and still having room for wanting a bit more it is a bit suspicious ( Im a newbie regarding electronics but I just to make sure there is nothing amiss ).

Tx

[Thermioniclife]

Try using a 300 ohm set of phones.

[Varail]

ok..I just tried with 150ohm Sen 660s and it is louder than the Beyer. I still  can max up the volume but at this point is as much as I can take. But I can still max the pot .. Is this normal ?

[Thermioniclife]

It depends on the input voltage, the type of music and the recording levels. If you happy, stay happy.

[Paul Joppa]

Your Crack appears to have the L-pad mod (the four resistors installed on the gain control lugs), which reduces the gain, usually by 12dB.

[Varail]

This is the kind of answer I was expecting to get .. I will have to ask someone to help me "fix" it. What does he needs to do ?

[Paul Birkeland]

99.99% of folks who use the Crack complain about how sensitive the volume control is, so I build that pad in by default when building a factory built Crack (which that is).

Your DAC looks to put out 2V or so of signal voltage, and you should still have about 12dB of gain available, which would give you 8.7V RMS (or 125mW) into your headphones.  This is a TON of output and would be ear splittingly loud.

I would very, very strongly suggest that there's some volume control on your PC that isn't turned up all the way (or on the DAC itself perhaps) and rather than modifying the amp, I would chase down where that bottleneck is first.

[Varail]

I used the 3.5 Line out of the Ifi Nano so the volume on it does nothing. Like any noob the pc volume setting were the 1st things checked ..
So what I get is normally I shouldnt be able to max the volume on the BHC on my Beyers without getting deaf so that means there is something here that eludes me ..
I forgot to say Im on 220V and the amp is on 120 (US)V so Im using a converter ( shouldnt matter, right ? ).

[kGlerup]

Using Beyer T1 2nd gen myself.
I have plenty of gain! Don't need to go higher than like 10 o'clock on the volume.
So sounds a bit strange this.

[Varail]

"99.99% of folks who use the Crack complain about how sensitive the volume control is, so I build that pad in by default when building a factory built Crack (which that is)."

"Using Beyer T1 2nd gen myself.
I have plenty of gain! Don't need to go higher than like 10 o'clock on the volume.
So sounds a bit strange this."

With the mod on or off ?
Your pot starts from 12 o clock also ? So starting from 12 you reach 10 ?

[Doc B.]

Have you tried other high impedance headphones to get a point of reference about the level setting? That might be the place to start. If it is only the T1s that won't play loud enough then you probably need to remove the pad. If other high impedance headphones (like HD650, etc.) don't play loud enough you may have an issue with the signal level coming into the Crack not being high enough.

[Varail]

Have you tried other high impedance headphones to get a point of reference about the level setting? That might be the place to start. If it is only the T1s that won't play loud enough then you probably need to remove the pad. If other high impedance headphones (like HD650, etc.) don't play loud enough you may have an issue with the signal level coming into the Crack not being high enough.

Headphones : Beyer T1 2nd gen (600 ohm) + Sen 58x/660s (150 ohm) + planars (I didnt bother trying)
DAC : Ifi Nano + Qutest

100% volume on PC

Track - Dua Lipa - Dance The Night (youtube) - Max volume

Results -

Beyer/Sen Im comfortable going from 12 (start) to 9 (out of 10) - I can go 10 even if unpleasant
Sen are overall a bit louder than the Beyer.

Changing DAC makes no difference.
Sounds signature is warm SS (Im getting no tubey spark) but at this point I feel that the volume is my primary concern since I strongly feel it doesnt behave like it should ..

[Doc B.]

Removing the pad will make it play louder. I your photo you can see a small tan resistor connected between the two outer terminals on the volume potentiometer (one end is where the white wire for the left channel is connected through a big tan resistor and the other end where the black wire for ground is connected). This resistor gets removed. There will be another small tan resistor just below it connected the same way to the potentiometer terminals closer to the chassis (right channel, red). Remove it too.

The next step is slightly more involved. There is a bigger tan resistor that connects the white wire the terminal on the potentiometer. That resistor needs to be snipped out. Then solder the loose white wire directly to the terminal where the big tan resistor was soldered. You now have the white wire connected directly to the pot terminal without the tan resistor in between them.

Once again there will be a similar larger tan resistor underneath that is connected to the red wire and to the lower terminal. Do that same thing here, remove the resistor and connect the red wire directly to the pot terminal.

All of this returns the input wiring to the stock kit configuration.

I would also advise that if you are hiring someone to do this rather than taking it on yourself, a competent technician should understand what an input pad is and know exactly what I am describing here. If he does not, find a tech with more knowledge.