Beresford Bushmaster DAC

[MartinT]

I am aware of that, Val, but I'm just trying to get Martyn back to listening again. He has a preamp and I'm suggesting that he tries it.

[Psion770]

Whereas I appreciate the efforts to help me listen, I spoke to Stan about a week ago discussing the use of a lightspeed which he suggested I steer clear off for technical reasons beyond me or to difficult to explain. He emailed me and suggested someone was having reasonable results with an NVA passive preamp, this is not powered. the icon audio passive was the nearest thing I could find
The icon audio uses hard wired circuitry and uses a simple pot to control output many people use their CD players to drive active speakers. I couldn't get the Bushmaster to work through the Icon at all no distortion nothing apart from the severe motor boating which it initially displayed see the original post
I tried the Bushmaster straight from the Wadia dock this time nothing I reconnected my system into the Caiman lo and behold it played. Even manually connecting the right coax input.
I then tried a new connector direct from the Wadia and the Bushmaster worked via the headphone outlet ... Go figure.
Something I'm doing is fundamentally not right i am concerned that putting a powered preamp into the system may make things worse or colour the sound. I am not an electronics engineer but if the output from the DAC is high enough surely a straight wire with no gain is preferable now confused Martyn

[sondale]

Silly question - are your headphones permanently plugged in to the Bushmaster?

[MartinT]

Good point - I believe that mutes the line outputs.

[Psion770]

No they weren't I used the headphones to listen to the Wadia using a short length of coax and it worked for a period of time then stopped, plugged the Wadiia back into the Caiman as in my normal system voila back to normal.

Regards Martyn.

[MartinT]

Martyn, can you separate out the two possible issues here please so that we can help you?

1) digital source is not being locked? What sources & cables have you tried? Are you verifying with headphones? Is it just the auto seek mode that doesn't work, or will it not lock manually?

2) locked source works via headphones but not out to a pasive/active preamp? What happens, do you get any sound at all? Have you tried a different preamp line level input?

[StanleyB]

I used the headphones to listen to the Wadia using a short length of coax and it worked for a period of time then stopped, plugged the Wadiia back into the Caiman as in my normal system voila back to normal.

Is this in the auto or manual mode? And did you try the Wadia again in the BM after that?

[barry-potter]

Whereas I appreciate the efforts to help me listen, I spoke to Stan about a week ago discussing the use of a lightspeed which he suggested I steer clear off for technical reasons beyond me or to difficult to explain.

what are these technical reasons? i run mine through a lightspeed without probs.

[HighFidelityGuy]

what are these technical reasons? i run mine through a lightspeed without probs.

I believe the reason will be due to the Bushmaster having a slightly high output impedance (due to it's passive output stage) and the lightspeed (and all other passive attenuators) having quite low input impedance and high output impedance.

Simply by the nature of their designs they are theoretically a slightly bad match. They will work but you may not get the full dynamic range and frequency response that's possible as the DAC will be having a tougher time driving your amp. This is the unfortunate trade-off with passive attenuators.

The output impedance of the Bushmaster isn't very high though, so the effect is likely to be subtle. Especially if the input impedance of your power amp is high (50K plus).

I used my Caiman (with the passive output mod) with a passive attenuator feeding amps with both 50K and 100K input impedances. With both amps I seemed to get plenty of dynamic range etc. Results will vary between systems though depending the equipment used. I think Stan is just trying to ensure that his customers are getting the best out of his products, which is understandable.

[jandl100]

Ah - that's interesting!

Over the last week or so I've been using a TVC passive pre with the Bushmaster, where previously I had used only active pre's, and the treble is just a tad rolled off and smooth. So I slipped in a slightly 'hot' interconnect and all is well with the world.

... mind you, some reviews of the TVC pre (a Bent Audio NOH) say that it's a bit on the smooth side, so it may not be down to interaction with the BM at all, just a characteristic of the pre.

Dynamics remain full-bloodied and pretty damn awesome from the BM!