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Set Up Advice Please– Valve Amp n Subs x 2


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So, I’ve just purchased a PrimaLuna EVO 300 integrated amp and 2 x REL T7i’s subwoofers. I thought set up would be relatively easy until I realised standard setup doesn’t seem to apply when you have a choice of 4 & 8 Ohm Speaker Taps. Both REL and PrimaLuna websites have conflicting information, or a lack of information, when trying to set up a 2.2 system. 

 

I want to setup the subs using the High-Level Inputs and NOT the 2 sub outs on amp. 

 

According to the REL support page a single sub should be connected using the following instructions https://rel.net/how-to-connect-your-rel-to-a-tube-amplifier.

 

From what I can make out, this is non-balanced approach and doesn’t give any insight on how to connect a second sub. I believe the EVO is fully balanced and may cause damage if connected in this manner

 

I have been advised by a REL sales rep to connect as follows - Red and yellow wires HOT wired into the 8 Ohm positive speaker output and the Black wire to be plugged into an unused Aux input on the amp (soldered to an old RCA as the PrimaLuna doesn’t have a grounding point or can’t be grounded to the chassis). The thought of tinkering with a soldering iron leaves me a little nervous and I just can’t believe there isn’t a simpler solution. 

 

Any advice or work arounds would be greatly appreciated. It appears I’ve purchased beyond my expertise as first time valve owner. Thanks in advance guys. 

 

Regards 

Max

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At least please reconsider using the sub outputs from your amp. I won't labour on the point unless you want to know the arguments for doing so, if you're wedded to the high level idea.

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Probably not the news you want to hear, but I’m currently in conversation with a REL support about connecting my REL to a valve amp with no sub outs. Connecting as you described above (hi level with the floating black wire or otherwise connected to an unused aux via rca to the LFE out on REL) emits a very loud constant noise when the sub is switched on (more that I keep the amp off to hopefully prevent damage). 

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45 minutes ago, Ittaku said:

At least please reconsider using the sub outputs from your amp. I won't labour on the point unless you want to know the arguments for doing so, if you're wedded to the high level idea.

 

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I’m not wedded to the high level inputs, however it appears to engineered this way as the preferred connection option, they spent the cash on RND and would like to experience their design concept to the fullest, obviously without damage or hum. Cheers 

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2 minutes ago, Maximus101001 said:

I’m not wedded to the high level inputs, however it appears to engineered this way as the preferred connection option, they spent the cash on RND and would like to experience their design concept to the fullest, obviously without damage or hum. Cheers 

 

It's REL's "USP" - nothing more!

 

One has to ask, though - why don't all sub mfrs recommend this ... if it's so good?  After all - no other power amps (apart from the ones in REL subs) are driven with spkr-level connections - rather, line-level connections (RCA or XLR).

 

AIUI, this concept of driving the sub's amp from the main spkrs' terminals comes about from the - IMO, dubious - claim that the 'sonic flavour' of the amp driving the main spkrs is imparted to the amp driving the (REL) sub, when you use high-level connections.

 

Andy

 

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Just now, Maximus101001 said:

I’m not wedded to the high level inputs, however it appears to engineered this way as the preferred connection option, they spent the cash on RND and would like to experience their design concept to the fullest, obviously without damage or hum. Cheers 

Okay then to explain why high level inputs have a reputation you have to look at Rel's history. Subwoofers a long time ago were renowned for being very low quality sound and Rel revolutionised the idea of using subwoofers for high quality audio. However they did so in an era where the concept of multiple line level outputs, with dedicated outputs to subwoofers, was non-existent. So they developed their entire line of equipment around high level inputs. Initially subwoofers were passive and required their own amplification, but as time went on, subwoofers became active but still worked off the high level inputs because that was the only way to connect them and they needed to reduce the signal appropriately to be able to amplify it themselves. Fast forward 30 years and subwoofers have changed dramatically as have preamps, integrated amps, and AVRs, for many to include outputs dedicated to subwoofers. Very few new manufacturers of subwoofers even bother with high level inputs because of the simplicity and unmodified signal obtained from line level inputs. So what's the problem with high level inputs? Well as you've seen above, one huge problem is the bulk of subwoofers that work off high level inputs expect a common ground neutral since that's how they work internally, and many amplifiers have a floating signal without a common ground - valve power amps, bridged power amps, and class D. Is there an audible advantage to working off the high level inputs? Instead of giving a separate subwoofer amplifier a pure line level signal, you are now running it through a power amp and adding more to the signal than was originally there - the frequency response is altered by the power amplifier, and distortion is added. Any concept that it's "better sounding" is because Rel invested so much into their high level input approach that they have to keep marketing it as being better now, as they can't get rid of it, and existing Rel owners who are continually upgrading to newer Rel subwoofers are wedded to the approach, still believing in it being better.

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Thanks for everyone’s input and insight into the sub bass genre. 
 

Outcome for all those trying to connect 2 RELS via High Level inputs  into Tube Amps WITHOUT sub outs. 

I followed the directions of REL sales rep and connected into the 8 Ohm speaker output and grounded to unused RCA input for BOTH subs. 
 

 Very happy with results with NO hum and seamless integration of main speakers n subs. 


Amp has been running for a few hours and already addicted to their warm cozy sound. 
 

Thanks  again guys 

Max 

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9 hours ago, Ittaku said:

Okay then to explain why high level inputs have a reputation you have to look at Rel's history. Subwoofers a long time ago were renowned for being very low quality sound and Rel revolutionised the idea of using subwoofers for high quality audio. However they did so in an era where the concept of multiple line level outputs, with dedicated outputs to subwoofers, was non-existent. So they developed their entire line of equipment around high level inputs. Initially subwoofers were passive and required their own amplification, but as time went on, subwoofers became active but still worked off the high level inputs because that was the only way to connect them and they needed to reduce the signal appropriately to be able to amplify it themselves. Fast forward 30 years and subwoofers have changed dramatically as have preamps, integrated amps, and AVRs, for many to include outputs dedicated to subwoofers. Very few new manufacturers of subwoofers even bother with high level inputs because of the simplicity and unmodified signal obtained from line level inputs. So what's the problem with high level inputs? Well as you've seen above, one huge problem is the bulk of subwoofers that work off high level inputs expect a common ground neutral since that's how they work internally, and many amplifiers have a floating signal without a common ground - valve power amps, bridged power amps, and class D. Is there an audible advantage to working off the high level inputs? Instead of giving a separate subwoofer amplifier a pure line level signal, you are now running it through a power amp and adding more to the signal than was originally there - the frequency response is altered by the power amplifier, and distortion is added. Any concept that it's "better sounding" is because Rel invested so much into their high level input approach that they have to keep marketing it as being better now, as they can't get rid of it, and existing Rel owners who are continually upgrading to newer Rel subwoofers are wedded to the approach, still believing in it being better.

 

Great explanation, Con - for what I have always believed.  :thumb:

 

Thanks,

Andy

 

PS:  Hopefully, people today who are getting into subs will realise that the REL 'USP' (connecting subs via high level inputs) is now completely discredited - and other mfrs' subs are a better way to go.

 

Edited by andyr
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5 hours ago, Maximus101001 said:

I followed the directions of REL sales rep and connected into the 8 Ohm speaker output and grounded to unused RCA input for BOTH subs. 

I don't understand why he didnt tell you to connect the black wire to the speaker negative terminal(s).

 

11 hours ago, Maximus101001 said:

I believe the EVO is fully balanced and may cause damage if connected in this manner

It won't cause damage.

 

When the EVO says it's "fully balanced" this dosn't mean balanced at the speaker terminals.    Just up until the output transformer.

 

 

Depending on how your amplifier is desgned inside .... connecting to the speaker negative terminal , like the standard litrature says, may produce a better quality result..... although it might not be noticable.

 

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I’m sure this topic will arise as some point in the future within SNA. It appears people have strong views based on experience, both first hand and from others. 
 

If I could make the point, without sounding ungrateful or disrespectful to other members, particularly to those seasoned audiophiles,  my original post requested information related to connecting newly purchased items. 
 

i posted for instructional purposes, not to debate the pro and cons of High Level vs Low Level. I required technical expertise on the wiring layout. The above comments may have been more relevant if I was shopping around or researching equipment, but I’d already made my purchases and only needed a How To to my original post. 
 

But hey, all worked out well in the end. Apologies if this causes offence. I’m new to hi fi and this was my first post ?
 


 

 

 

 

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8 minutes ago, davewantsmoore said:

I don't understand why he didnt tell you to connect the black wire to the speaker negative terminal(s).

 

It won't cause damage.

 

When the EVO says it's "fully balanced" this dosn't mean balanced at the speaker terminals.    Just up until the output transformer.

 

 

Depending on how your amplifier is desgned inside .... connecting to the speaker negative terminal , like the standard litrature says, may produce a better quality result..... although it might not be noticable.

 

When you say Negative terminal, what do you mean? There is only 8 Ohm, 4 Ohm and O Ohm on both channels. No positive or negative. Am I missing something? I probably am. LOL :) 

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2 hours ago, Maximus101001 said:

I’m sure this topic will arise as some point in the future within SNA. It appears people have strong views based on experience, both first hand and from others. 
 

If I could make the point, without sounding ungrateful or disrespectful to other members, particularly to those seasoned audiophiles,  my original post requested information related to connecting newly purchased items. 
 

i posted for instructional purposes, not to debate the pro and cons of High Level vs Low Level. I required technical expertise on the wiring layout. The above comments may have been more relevant if I was shopping around or researching equipment, but I’d already made my purchases and only needed a How To to my original post. 
 

But hey, all worked out well in the end. Apologies if this causes offence. I’m new to hi fi and this was my first post ?

Not offended. I only politely suggested you try the line level connections, and then only elaborated because you said you weren't wedded to high level connections. So long as you have it working safely and have a good result, it makes no difference what theory says.

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Guest jakeyb77
3 hours ago, Maximus101001 said:

When you say Negative terminal, what do you mean? There is only 8 Ohm, 4 Ohm and O Ohm on both channels. No positive or negative. Am I missing something? I probably am. LOL :) 

This is the reason your original question probably didn’t get the answer you seek. 
 

Your way of connecting the amp sounded like trying to swim across crocodile infested water when someone had built a perfectly good bridge you chose to ignore ?‍♂️
Members were just trying to simplify something you’ve made difficult. 
 

The day you start believing manufacturers claims over real world experience is not a good day. 
 

Glad it all worked out for you though. 

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I like all good subs, REL in particular. I have used single REL subs in the past few decades connected as REL says (high-level) and it was great. After migrating to using dual Storm 5 subs some 15 years ago, I decided to use the two line outs from my Leben preamplifier into REL (LFE) inputs. Partly this was due to having a Wyred4Sound Class D amp at the time--and my concerns about causing trouble with high-level connection. I understand the crossover inside the REL is around 30Hz when used like this.

 

The overall system sound remained excellent. I couldn't tell the difference. Then or since.

 

Line level was a particularly convenient setup later after buying an Anti-Mode 8033 equaliser for the subs. This really clinched the low frequency deal for me after enjoying room equalisation!

 

While what REL says might be technically correct according to their research (as @Ittaku states), like a lot of things in audio it's whether you can perceive it. 

 

Just my 2c worth

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