BC300 MKII gain related observations

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bjh
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Post by bjh » Sun Mar 05, 2006 2:31 pm

The BC3000 contines to be a joy, but also an enigma, take gain for example. For starters in comparison to my last pre the gain is quite low, so I find I have to turn it up quite a bit (I know, I know ... turning it up means less attenuation but I'm going to stick with common language) for my normal listening levels; I suspect the BC22MKII is also less sensitive than the average power amp.

But the weird thing is that with everything else I've ever owned turning it up always meant more (static) noise, but not the BC3000, it just gets louder, nothing else!

Case in point, today I was listening to Supertramp "Crisis what Crisis" LP (I don't mind admitting I still like the odd thing from earlier days even if my taste is quite a bit more sophisticated these days :huh: :o), and to get to the levels I wanted (blasting it!) I darn near had the BC3000 completely open!

Noisy? Heck no!, it was the cleanest I've ever heard it, great impact and weight and easly the best in sorting out everything going on in the complex jigsaw puzzle studio mixes (which the LP clearly is).

ps.

Phono pre in this case is a Dolan PM1 (used as dedicated phono stage, output from tape out). The Jolida JD9 I was using is out, just didn't gel with the BC3000 no matter what I did, still too noisy even with low noise tubes. The (all SS) Dolan matches much better.

Temptation to try a BC27 almost hurts! ... but I'm putting up a valiant defense, and thus far holdng my ground! :D :D :D


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PhilNYC
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Post by PhilNYC » Mon Mar 06, 2006 3:03 pm

bjh wrote: For starters in comparison to my last pre the gain is quite low, so I find I have to turn it up quite a bit (I know, I know ... turning it up means less attenuation but I'm going to stick with common language) for my normal listening levels;
FYI - if you remove the cover on the BC3000, you'll find a switch on each Shallco which allows you to toggle between "high gain" and "low gain". I suspect you have it set on "low gain". The difference between the two is about 1/4 of the volume control (eg. setting the volume knob at 2 oclock on "low gain" will be about the same as at 10am on "high gain")...
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Gilbert Y
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Post by Gilbert Y » Mon Mar 06, 2006 4:47 pm

bjh

Be careful when you flip the volume switch to high. Make sure you start again from 6 O'clock position on both volume controls. Because if you don't, you may be in one heck of a not so good surprise with the volume.

The least, it will shock you. The worst, buy new woofers. Cause' it can be very loud.

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bjh
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Post by bjh » Mon Mar 06, 2006 5:35 pm

Gilbert, Phil ...

Doesn't the HIGH position just select a (series) resistor that has a smaller value than the resistor used in the LOW position?; i.e. HIGH/LOW just switches between to different resistors, correct?

If this is the case then in the HIGH position there is less attenuation, or equivalently, more gain.

Thus with the swiches in the HIGH position doesn't this mean that the absolute gain possible IS higher?

I've gotten mixed messages on this so I like to know how it works ... sorry in advance if it is a stupid question.

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Gilbert Y
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Post by Gilbert Y » Mon Mar 06, 2006 8:16 pm

The high/low switches on the Shallcos are level switch. I don't use the word gain because it is not a switch which adjust the gain. The gain of the preamp is 23.5db. That doesn't change. To flip the switch to high position, it will give you less attenuation, therefore more volume.

What you said is about right but not exactly in technical terms. The bottom line is flip the switch to high postion, more volume, low position less volume for a give postion which the knobs are pointing at.

I have long given up to correct anyone who use the word "gain" to discribe those switches. Because doesn't matter how many time I correct them, no one seem to listen. They keep using the word "gain". :( :unsure: :blink:

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bjh
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Post by bjh » Mon Mar 06, 2006 9:25 pm

Gilbert,

I actulayy follow that! Thanks! (I must just a little smarter than I thought :huh: :blink: :blink: :huh: )

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davei
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Post by davei » Tue Mar 07, 2006 11:19 pm

temptation to try a BC27 almost hurts! ... but I'm putting up a valiant defense, and thus far holdng my ground! :D :D :D
bjhTt
i have bc27 and love it, go for the bc27pi! less shipping in the long run getting it upgraded down time! and yes i want a bc27pi too! wish i bought the bc27pi in the the first place......i blame P-dawg, i can't blame myself! phil will talk! no worries friend!

dave

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bjh
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Post by bjh » Wed Mar 08, 2006 11:12 am

Wow!

Flipped the switches and sure enough way more gain [smack], Ouch! ... I mean way less attenuation [smack amack] Ow! ... I mean less input bleed away [smack smack smack] ... OK, OK, it's a lot louder!!!

...

On the downside I replaced the bulb and still no light ... what the heck could go wrong with the light bulb socket!!! Ah, heck, I guess the (no glow) makes my BC3000 unique and distinctive! <_<

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Gilbert Y
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Post by Gilbert Y » Wed Mar 08, 2006 12:56 pm

bjh

Wiggle the light bulb in the socket a little bit. Sometime dirt, and solder flux from the light bulb base itself may prevent making contact between the light bulb and the base.

Any, what light bulb did you put into the preamp. The preamp should be 24PSB and the power supply is 120PSB. If you put a 120PSB into a 24PSB, it won't have any light.


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bjh
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Post by bjh » Wed Mar 08, 2006 2:22 pm

Gilbert,

Well that explains it!!!!!!

Since it's easier to open the power supply than the pre-amplifer (i.e. rip the entire system apart) I of course opened the power supply to get have a look at the existing bulk for part number information!!!!!

I just assumed they would be the same!!!!

Oh well, at least I fixed the gain issue [smack] OWWWW!!! :angry:

--

Thanks! :D




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bjh
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Post by bjh » Sat Mar 11, 2006 6:02 pm

Addendum re: Jolida JD9 Phono stage

Thought it wise to add a quick note regarding the synergy issues I had reported with JD9 and the BC3000 MKII.

Well the *real* issue has now been confirmed to have been high frequency nasties from a Denon DL 103 that had aged beyond its prime. With a new 103 mounted the JD9 has regained it's position as preferred phono stage in my system.

It is unfortunate that this worn cartridge issue happened to coincide with the introduction of the BC3000. The good new is that it now appear the JD9 still presents great sound for peanuts even when teamed with something as lofty as a BC3000.

Hence a brief description of the JD9 *sound* seems appropriate ... extroverted fairly upfront/forward character yielding high excitement/involvement value, rich deep bass (even if not last word in bass quality but still plenty darn good), fantastic sound stage width and even depth, and finally great color range that combined with image density yields very respectable resolution and 'look-into' factor. Many characteristics, especially soundstaging (width and depth), appear appreciably enhanced by benefit of being teamed with the BC3000.


shirtnosleeves

Post by shirtnosleeves » Fri Mar 17, 2006 9:40 pm

I used to see many blue lights at chris's place.....

you call him, and he will give you a few.

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