Preamp into two "monoblocks". Am I getting this right?

[jackshultz]

Hello. Total newb at this sort of thing. I own a vintage reciever and a pair of 6ohm (dipping to 4 ohm) speakers (87% sensitivity) The setup works fine but I feel the speakers
could benefit from a bit more "grunt". Therefore, I want to experiment and add two cheap Chinese amps to act as monoblocks.
Am I right that once I remove the connecting pre / main pins in the reciever I can then use two RCA splitter cables; one connecting left preamp out to the left inputs on both amps and the same for the right channel? If so, are there any particular models of Chinese amps I should be looking at?
Your input would be greatly appreciated.
Jack

 

[Chrispy]

What particular receiver do you have? You mean 87dB sensitivity for the speakers? What speakers particularly? Why cheap monoblocks, what will that accomplish?

 

[Blumlein 88]

If the amps you get are monoblocks they will only have one input. So no splitter. Left pre out once you pull the pins goes to the left amp. Right pre out goes to the right amp.

If they are stereo amps which can be bridged and you wish to bridge them, again once bridged left out to left amp and right out to right amp.

If what you have in mind is bi-amping, then a splitter from left output to both inputs on left amp, and right output to both inputs on right amp.

Good idea on questions like this to tell us as much as you can. Make and model of your receiver and if you know which amps you plan to get then make and model of those.

 

[jackshultz]

If the amps you get are monoblocks they will only have one input. So no splitter. Left pre out once you pull the pins goes to the left amp. Right pre out goes to the right amp.

If they are stereo amps which can be bridged and you wish to bridge them, again once bridged left out to left amp and right out to right amp.

If what you have in mind is bi-amping, then a splitter from left output to both inputs on left amp, and right output to both inputs on right amp.

Good idea on questions like this to tell us as much as you can. Make and model of your receiver and if you know which amps you plan to get then make and model of those.

Thank you for your reply. The Reciever is the Rotel RX 600A (30W at 8ohms) So bridging (I guess?) is what I want to do. How would I bridge an amp exactly? I've heard of bridging of course but it's actually pretty hard to find out exactly how to do it on YT. Can you help? As far as the two amps then I am open to suggestions. I was thinking about maybe the SMSL A300 or Aiyima 07 (or A7 Pro) ?

 

[jackshultz]

What particular receiver do you have? You mean 87dB sensitivity for the speakers? What speakers particularly? Why cheap monoblocks, what will that accomplish?

Thank you for replying. The reciever is the Rotel RX 600A (30W at 8ohms). Speakers KLH Model 5 ( I wrote 87% instead of dB!) I'm looking at cheap Chinese amps because of cost and because I'm really doing this as an experiment.

 

[Chrispy]

More power might help, but doing it with monoblocks is somewhat extra expense for no particular benefit. I'd just use a more powerful stereo amp, whatever country it is made in. Using the pre-outs would be the way to go in connecting it. Bridging just reduces impedance handling, and you're generally better off simply with a more powerful amp in the first place.

 

[jackshultz]

More power might help, but doing it with monoblocks is somewhat extra expense for no particular benefit. I'd just use a more powerful stereo amp, whatever country it is made in. Using the pre-outs would be the way to go in connecting it. Bridging just reduces impedance handling, and you're generally better off simply with a more powerful amp in the first place.

Yes. You're right. I am overthinking this. Thank you.

 

[kemmler3D]

The Model 5 could probably use a bit more juice, but the Rotel is within the recommended spec for these speakers. If you go up to 200w you'll get something like 8-9 more dB out of them at most - which is a lot but maybe not night-and-day.

Bridging an amp means taking a stereo amp and doubling up the channels to make a mono amp, so you can send more watts to one speaker. Not all amps support this.

If you are doing monblocks, you will not be bridging. There's no inherent advantage to monoblocks over stereo amps, but since they use different power supplies, it can matter at very high wattages.

I wouldn't bother doing this unless you go for 200 WPC at least, if you go to 100ish then you're only going from a max of 100dB SPL to 105ish. Try some numbers for yourself: http://www.hometheaterengineering.com/splcalculator.html

I wouldn't get hung up on monoblocks, what you're looking for is just a lot of cheap power, and (I guess) clean if possible. There are a lot of options out there if you don't care what it looks like and can tolerate a bit higher noise / distortion threshold. https://www.monoprice.com/product?p_id=18513 two of these (actually, you would bridge these) gets you 450wpc @ $500... not bad. Per @Blumlein 88 these amps actually are bad until proven otherwise.

Here we have 200-300 WPC @ $329 https://www.sweetwater.com/store/detail/XLI800--crown-xli-800-power-amplifier - both of these will have higher noise and distortion than the fan-favorite Hypex and Purifi options, but at about 1/3 the price for new gear.

I personally snagged some Nord NC500 monoblocks on Craigslist a while back @ $600 for the pair, a solid deal, but probably overkill.

 

[Blumlein 88]

Bridging first off cannot be done with all amps. Some you can and how it works varies, but is not too hard. The manual should show you how. I might try one SMSL A300 as it has quite a bit more power. Then depending upon how that suits you, you could buy a 2nd and bridge them. One may be enough.

What are the sources of music you have? You might skip the receiver altogether.

I like @kemmler3D suggestion on the monoprice basic amp. Get the largest one and it is 150 wpc in stereo. I don't know if using this one bridged is a good idea with your speakers as they suggest minimum load of 8 ohms bridged. I also wished it had been measured somewhere. They do have a 30 day return window if you don't like it.

 

[Zek]

Find a used Rotel power amp and pair it with your receiver.

rotel RB power amp - Google претрага

 

[kemmler3D]

I also wished it had been measured somewhere.

That's a good point. Monoprice is a pretty reliable brand, but not infallable, and wattage specs are one of the most common ways manufacturers overstate the performance of their gear. There is a chance you don't get all the watts you pay for unless someone has independently measured the product.

 

[Blumlein 88]

Lots of complaints on the Monoprice Unity amp in Amazon reviews about them having hiss and buzz (and a fair number that just quit working). I'd say avoid.

 

[jackshultz]

Thank to everyone who took the time to respond. Food for thought here, but it's clear that the monoblock idea is maybe for another time

 

[raindance]

What are you trying to achieve with the extra power? More volume or a different sound perhaps? Placement, sitting area and room acoustics are the first place to look.

 

[Livewire]

I'm running my Model 5s with a Buckeye nc252mp stereo amp, with a MiniDSP Flex as the pre. Sounds great to my ears!