Stereo power amp or monoblocks?

jt1stcav

Up and Coming Bottlehead
I have an 8 WPC 300B single-ended stereo power amp from BEZ. This same manufacturer also builds a newer 300B monoblock version that's 10 WPC. I'm happy with the sound of my 2-channel amp, but I am considering maybe purchasing BEZ's monoblocks to replace my current amp.

I'm wondering if there's any real advantage to doing so? What is the main reason for any manufacturer to build monoblock power amps and also offer basically the same amp spec-wise in a 2-channel stereo configuration? Do monoblocks generally sound superior to stereo amps, or is it all hype?

Your opinions would be greatly appreciated! :yes:
 
jt1stcav,

I'm gonna go out on a limb here-but bear in mind I'm just getting started in tube DIY and I'm still climbing the learning curve.

I'd think the most obvious difference would be in the power supply-with a separate pwr xfrmr and power rectifiers for each channel, you might gain better voltage regulation and less sagging on low-frequency and extreme transients. I think it's generally believed this leads to better channel separation and therefore more precise "imaging." The extra space may also help with magnetic coupling of chokes and output transformers-something that can become an issue in the confines of a stereo amp.

I would think with a properly designed and grounded circuit, the extra space afforded for the gain/phase inverter sections and output tubes would not make much of a difference.

I have to admit there's the extra "cool" factor that comes with mono-blocks-I know I like the look of them!

OTOH, I think that a stereo amp with a shared power supply could do just as well as a pair of monos-provided that power supply is up to the task. Problem then becomes fitting a power supply that big on a single chassis-I'm running into that issue myself on my DIY amp.

I guess bottom line in my opinion is: when it comes to power supplies, when you beef it up to a level that can loaf along you'll pay for it-either in the form of monoblocks or a beefy stereo amp. I'm not familiar enough with the BEZ stuff to know if the shared power supply of their stereo amp can compete with their separate power supplies for mono-blocks.

If the power supply on your stereo amp IS beefy enough to compare favorably to a pair of monos the only difference may be in how much you spend to get the same sound.

Just my take-and bear in mind I'm still learning!

Best,
mojo
 
Crosstalk could/can be a issue, there is a way to check it if the amp has VC's.
Input one side and leave the other unhooked. Leave the volume control on the hooked up side turned down. Then crank the VC on the unhooked side.
If there is crosstalk, the unhooked side's OPT will start singing, either on the LF end or the HF end or possibly both. Swap sides and try the other side the same way to check crosstalk for the other channel.

But as Mojo says a well designed supply and layout makes for a fine stereo tube amp.

8 to 10 watts won't matter much, Jim. Unless you are ready for change.
 
Having everything separated will make sure there is no cross talk but I think the main thing that separate power supplies on separate chassis make for smaller amounts of vibration and noise than you would get from a shared one. Of course there is no guarantee it will be quieter but think that was the main thing that caused mono blocks to come back.
Paying for 2 PSs doesn't make sense just cause it looks cool, unless you just have to much money and need to show off your toys.
 
All else being equal, monoblocks in theory will have better imaging and soundstaging. The fact that these are 10W Vs. 8W for the stereo helps too.
Jack
 
With the huge amount of current that the inefficient DHT 300B absorb to make there wattage the separate power supplies could have a huge effect. If you can afford it go for it I bet you will hear the difference!

Now if I could just get you to spend some cheese on a USA made product ;)

Craig
 
LOL! :lmao:

Craig, the BEZ monoblocks are only $670/pair, as opposed to your wonderful VRDs, which are over $2500/pair. I know, I know...you get what you pay for. It's not that your monoblocks aren't worth what you charge (really, you could charge twice as much and they'd still be a bargain). It's just that I'm on a very fixed income and I couldn't even afford the BEZ monoblocks unless I also sold something (and I've sold most what I own already when I was laid off and went bankrupt). :cry:

Do you have financing available? I'll make payments on 'em each month. :naughty:
 
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Well first off you qualify for the AK and Klipsch discount so there only $2299 a pair.

Well don't sell your Sole Jim ;)


For you I'm sure we could work out something but then you may have to sell your sole ;) Oh and lets get something clear I WILL NOT take the BEZ gear in on trade :D :naughty:
 
Let me save up a few year's worth of income tax refunds, and then we'll talk. :yes:
 
Filet of Sole has a pretty short shelf life and if I thought I could trade fish for good amps I would buy a fishing liscense.

Sorry, that was in poor taste and I should delete it, but I am a sick and twisted individual, though an honest trader.
Craig I will trade the the weight of your amps for Sole anytime, but considering how deliveries work you will just have to accept frozen and not fresh.

You can blame this post on the post traumatic condition I am in after being in Tulsa with Russman.
 
jt1stcav said:
I'm wondering if there's any real advantage to doing so? Do monoblocks generally sound superior to stereo amps, or is it all hype?

Your opinions would be greatly appreciated! :yes:
I know it from the fact that mono blocks have the following advantages:
1. No interaction between the left and right channel since 2 power supply is now used. No cross talks too.
2. The best speaker cable is no/short cable, so mono blocks enable one to put units close to speaker and have a short speaker cable.But........longer signal cable!!!!..........yes, the degrading is less significant ( or nil )if good quality signal cable is used, plus a proper designed preamp with low output impedance, not the preamp section out of a receiver.
3. Mono block usually has more power supply ratings to justify their much higher pricing, hence higher maximum power output.
I had used Krell KMA mono block feeding Apogee Duetta.
Have fun.
 
Shorter speaker wire are a better route then shorter IC's Hmmmmmm. I would have to be skeptical on that one. In my experience the lower the signal the more prone to degradation. Just take a TT for instance the slightest change in the cables whether it be tone arm or IC can have a huge effect!

Craig
 
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