New power amp for my BHK Pre - Spec check as OK please?

Audio Components Amplifiers
1

As above,
Been cycling through power amps to improve my system going forward and be a good match for my BHK Pre.

I know the BHK 250 would be a good call, but out of budget at the moment, may look at that or one of the new Macs in the future.
So back to the present. :slight_smile:

Currently Iā€™m using a ā€œvintageā€ Rotel RB-981 (100 wpc@ 8 Ohms) and very nice it sounds too.
Thereā€™s quite a drop to its 4 ohm output though suggesting maybe not as robust as it could be.

Taking ownership soon of a just serviced and recapped Densen DM-30 power amp.
Again, an older model but of very high quality, 100 watts into 8 ohms, 200 into 4. Dual everything, basically monoblocks in 1 chassis.

1000Ɨ750 85 KB

So thinking in terms of a match for my BHK Pre?

(I have the matching Densen DM-20 preamp, also recently recapped and a great match), but found the BHK to be a better Preamp.

Thinking of things Input voltage/ output voltage, impedance matchingā€¦etc.
The Densen has a V_inp of 1V for instance, the BHK V_out is 4V.

If I link to the spec sheet of the Densen power amp here, would some kind Soul with more technical nous than I have take a quick look for me please?

http://hififreaks.dk/Densen%20NEW%20Site/img/Owners%20manual%20for%20DM%20series.pdf

Anything stand out as a potential issue?

Thanks. :slight_smile: :+1:

2

Its an older amp so just want to double check.
Thanks. :slight_smile:

Thinking in terms of:

Input Sensitivity
1.0V
Input impedance
22 Kohm
Storage Capacity
80,000 uf
DC output offset
ā€œless than 20 mvā€

Much obliged for any comment.

3

Anyone?

Picking the power amp up in a couple of days, just want to make sure the BHK Pre will play nice with it.
Power amp has 1v input, believe BHK has 4V output?

Thinking in terms of gain structure between 2 amps.

Thanks.

EDIT
Checked the specifications of the BHK 250 powe amp?
ā€œSensitivity for rated output power of 250 watts into 8Ī© 1.3Vā€˜

Densen amp input sensitivity is 1V

So 1v compared to 1.3v
Nothing to be concerned about with amp matching?

4

There is nothing in the specs that would indicate an obvious mismatch though your volume will be slightly higher at lower numbered settings than would be the case with the BHK amps which are 1.3 volts. Unless your speakers are extremely sensitive then tube noise shouldnā€™t be much different. You are always going to have at least a double in terms of Balanced output to amps input sensitivity.

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5

Thanks for that.
Thinking if thereā€™s any over-volume issue I could attenuate it with the lossless volume in the DS Dac.

I had quite bad hiss issues with my BHK and speakers, (97db Horns) to the point where I moved the speakers on as being incompatible with the BHK Pre.
One had to go and it wasnā€™t going to be the BHK!

Could you explain a bit more please how you mean with a ā€œdoubleā€ with the balanced output?
The new power amp is unbalanced connection only, Just trying to understand more. :blush:

6

The maximum output voltage for the Balanced outputs is 4 volts but only 2 volts for the SE outputs. The gain for the Balanced outputs is 12 db while only 3 db for the SE outputs. You will however get more clicking noise with the SE outputs unless your tubes are tightly matched between the triodes. With the SE outputs and ā€œreasonableā€ sensitivity speakers you should have to get within a foot or so to hear any tube hiss if the tubes are good. What speakers did you end up with?

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7

Understoodā€¦and this sets my mind at ease.
Thanks.

Temporarily using my 2nd system speakers
Dali Zensor 5s, (88dB at 8 Ohms)

But eventually moving to Dynaudio Evoke 50s (87dB at 4 Ohms)
The Dynaudios are a great match for the Densen power amp, which doubles its 100w output into 4 ohms, sign of a good power supply!

8

You should be good with either speaker with quiet tubes.

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