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Carvin BX500: Pt. 3

#886
I just received my BX500 and it's nice and I like it. But. They sure did make some strange decisions in the design. It sounds good, the EQs are nice, and I like that the graphic EQ is after the effects loop. An effects loop is an absolute necessity for me.

The pre-EQ-only DI is only a little bit disappointing: this means I'll have to put a DI box in the effects loop. I don't care about the EQ, but there's *other stuff* in the loop. So, that's not ideal, but I can cope. This feature might be moddable, depending on how tight the layout is.

But... they deserve some sort of award for the most pointless use of a tube. It isn't just that the tube is located after the master volume (and the DI), although that in itself would be weird. What's really silly is that this circuit doesn't do anything, tonally. The cathode follower design--as linear as possible with no gain, whose entire point is to isolate the output from the input with no coloration...why bother? It's not amplifying, it adds no distortion or coloration of any kind... what exactly is the point? It doesn't even serve a useful purpose of isolating two sections because it's *optional*.

They could cut the cost of the amp by removing the tube circuit entirely, and just have a dummy switch on the back that says "TUBE". In fact, that might be what's in there--I haven't opened the box yet.

Very very strange.

It's still a very nice solid state FET-pre bass amp, and will work for my application, but they missed an opportunity there. It might be worth modding, but you'd have to repatch it into the input preamp and just no. *sigh*
 
#889
tekhedd said:
But... they deserve some sort of award for the most pointless use of a tube. It isn't just that the tube is located after the master volume (and the DI), although that in itself would be weird. What's really silly is that this circuit doesn't do anything, tonally. The cathode follower design--as linear as possible with no gain, whose entire point is to isolate the output from the input with no coloration...why bother? It's not amplifying, it adds no distortion or coloration of any kind... what exactly is the point? It doesn't even serve a useful purpose of isolating two sections because it's *optional*.
Click to expand...
Ah. I see the problem. You're analyzing it from an engineering perspective, not a marketing perspective. I know what you're thinking: The 4565 will swing max output voltage into as low as 10 Kohms. Without the tube, it would see the next 4565's input R (about 500 K ohms) in parallel with the 150 Kohm input resistor -- total piece o' cake. That internal output pair wouldn't even break a sweat. But it's all n/a when Marketing barges into the design meeting, pulls out a .45, and starts waving it around. :smug: I don't think anyone could count how many times a "placeholder" Chinese firecracker has sold an amp.

Just my opinion/imagination. I could be wrong. Maybe these things never happen.
 
#892
Jarrett said:
If you can live with 250 watts, the BX250 had a post out and no tube.
Click to expand...

The BX250 was what I initially wanted, but the lack of an effects loop was a deal killer. (Yeah, I know, on an ultralight amp...)

I'm still pretty much happy though. What I really need is a lightweight amplifier with a great EQ section, and I'm really liking the EQ. We'll see how the amplifier part holds up tonight at the gig... :)
 
#899
I've gigged my BX500 exclusively since Jan. 2012. Maybe 50 or so times with great results. Last nights gig (and again today) it sounded terrible. Tone is all fuzzed out and distorted. I changed cables, cabs, basses, bypassed the tube - everything and it still sounds terrible. I liked the little bast*rd but not at the moment. I ordered a GB Shuttle 6.2 in the mean time and will look into getting the Carvin unit back to serviceable on Monday but I don't know whats wrong with it.
 
#900
Open it up and dose the ribbon cables with deoxit and work them on and off a few times. 99% chance that's what it is. If that doesn't work, spray deoxit on the end of a 1/4" cable and work it in and out of the effects send and return jacks. Sometimes they corrode over time.

Good luck,
Liam
 

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