How to get a second pair of line level outputs from my amplifier?

[selfaddict]

Hello all.

I have done the best hifi upgrade of my life: I recently bought a pair of Bastanis Mandala Prometheus open baffle speakers. I would like to have additional line level output, so I could use this to drive my pair of XTZ Sub Amps. These amps will drive pair of 15" sealed woofers. My Art Audio Diavolo then only would drive Gemini tweeters and wideband drivers.

Is there any simple solution for this :scratch:?

[anthonyTD]

Hello all.

I have done the best hifi upgrade of my life: I recently bought a pair of Bastanis Mandala Prometheus open baffle speakers. I would like to have additional line level output, so I could use this to drive my pair of XTZ Sub Amps. These amps will drive pair of 15" sealed woofers. My Art Audio Diavolo then only would drive Gemini tweeters and wideband drivers.

Is there any simple solution for this :scratch:?

hi,
if you only have one pair of line level out sockets on your preamp then the simplest way is to use a splitter lead ie; a lead with one male plug which splits into either two female sockets [per chanel] or two male plugs.
the line level circuit should be able to drive both units.
hope this helps.
Anthony,TD...

[selfaddict]

Thanks for your reply.

I should have be more precise :o. Currently I am using Art Audio Diavolo power amp which was turned to an integrated amplifier by Tom himself at Art Audio. It has one pair of speaker connectors, three line level inputs and volume pot. Inputs are selectable from the front of the amp. So I do not have a separate preamplifier in use. Is the only way to purchase passive TVC type preamplifier with second pair of line level outputs to get where I want to be? I would like to drive the Sub Amps using balanced interconnects if possible :rolleyes:.




hi,
if you only have one pair of line level out sockets on your preamp then the simplest way is to use a splitter lead ie; a lead with one male plug which splits into either two female sockets [per chanel] or two male plugs.
the line level circuit should be able to drive both units.
hope this helps.
Anthony,TD...

[Reid Malenfant]

If you don't have a set of pre out phono sockets then the only choice you have is to either fit a pair & connect them to the output of the custom fitted preamplifier section or alter one set of inputs to make them outputs.

I'd hope that the output of the pre amp section is buffered, if it isn't you might find it difficult to drive certain power amps & it may not be wise to modify it.

I'm assuming from your description that this might be helpful or not as the case may be :eyebrows:

[Thermionic]

I am not familiar with your equipment so I might be writing complete drivel, I am also not sure what a 'passive TVC type preamplifier ' is, but starting from basics this would seem to be not that straight forward.

As mark says you need to get a pair of line outputs fitted to your amp. Typically the signals would be taken off the volume control’s wiper terminals. But apart from the possible need for buffering (to prevent possible effects from having your sub amps with their leads in parallel with the power amp in your integrated), your desire for a balanced output to the subs will add a further complication in that you will need either a balancing transformer or some electronics to do the same thing.

A possible way round this would be to get Art Audio to fit the line outputs (a bit of wire from the pot to a pair of phonos) and then use one of the professional ‘match boxes’ that are available (Canford Audio, Studio Spares and Alice come to mind, costing around £150 give or take) to interface domestic equipment to professional kit. This will then take the single ended output from your amp, buffer it and convert it into a balanced signal via XLR3 connectors to drive your sub amps. The only problem with this approach is that you need to find a match box that sounds acceptable to you, as some of them are by no means perfect.

I am of course assuming that your XTL amps have built in low pass filters.

[John]

The Bastanis are really nice you have some great speakers
Clive uses Bastanis so perhaps he maybe a long latter
Here is how my set up works on my system
I have a passive pre/dac this feeds the power amp which in turn drive mt Hawnthorne silver Iris speakers
I use 2 bass sub plates for stereo bass (some of the bass frequencies are in stereo so in my view uits worth the effort) I use the HT lead from my speaker input terminal and connect to the sub plate and then back to the Augee bass drivers, using phase control allows me to get the intergration issues sorted. I could also use my pre out in the way Anthony described by using Y rca splitters and link into my sub. If you amp has a tape monitor or a seperate pre out you might be able to use this to send sound to th sub and speakers
I hope this helps
To be honest often people say that the LT power leads are better but I have no compliants running HT leads of the speakers

[Clive]

I'm working from my phone so I've not fully digested the problem....but one route is to feed the bass amp from your amp outputs, with high efficiency speakers the speaker levels input on bass amps often are not the right level. You can get around this by inserting a 1k resistor in the cable from the amp speaker output and then take this to the LINE level input on the bass amp.

[selfaddict]

Many thanks for everyone for their input to get my problem solved. I have been digging a bit deeper and have learned loads again :).

It seems the best solution would be to get separate preamp with two pair of outputs, one single ended and one balanced. The single ended outputs I could use to connect to one of the single ended Diavolo inputs and the balanced I could use to drive the woofers. This is something that I was after, now it is just the question how to match to very different power amplifiers to this pre amp.

Diavolo input impedance is 380Kohm and the Sub Amp 1 will be 10Kohm or 5Kohm depending which inputs are used. So to make things simple I need preamplifier with two sets of outputs(one balanced one single ended) with output impedance 1Kohm or less if possible.

Any suggestions :hmm:

[Reid Malenfant]

4 very high quality op amps would do the job as long as a good power supply is available of the right sort of voltage.

Incorporate them after the volume control, 2 (left & right) acting as unity gain buffers & another 2 following those as inverting buffers (unity gain again).

You could feed the Diavalo which you state has 380K ohm input impedance (odd) from straight off of the volume control output. You can take balanced outputs to feed the low impedance subs from the output of the non inverting & inverting outputs of the op amps :) You'd obviously need to fit XLR output sockets or hardwire a cable inside. Either way you'd be drilling holes :doh:

Actually 2 dual op amps would do the job... Nothing wrong with a bit of DIY as long as you can do it ;)

[selfaddict]

Hello Mark.

I am totally useless when it comes to DIY electronics, best I can do is soldering interconnects :rolleyes:. I am not 100% sure about the input impedance, I have also seen a figure 220K ohm. But if I have understood this right the low input impedance of the woofer amps will limit my choice of pre amplifiers.


4 very high quality op amps would do the job as long as a good power supply is available of the right sort of voltage.

Incorporate them after the volume control, 2 (left & right) acting as unity gain buffers & another 2 following those as inverting buffers (unity gain again).

You could feed the Diavalo which you state has 380K ohm input impedance (odd) from straight off of the volume control output. You can take balanced outputs to feed the low impedance subs from the output of the non inverting & inverting outputs of the op amps :) You'd obviously need to fit XLR output sockets or hardwire a cable inside. Either way you'd be drilling holes :doh:

Actually 2 dual op amps would do the job... Nothing wrong with a bit of DIY as long as you can do it ;)

[Clive]

Juha, if you want a new preamp then go down that route. For the sake of the cost of 2 x 1K resistors connected to a set of interconnects please try this. The cost is virtually nothing.

Along the line of Mark's suggestion I for a long time ran a Burson buffer connecting to the XTZs, this also works well.

[selfaddict]

Hello Clive.

Sorry I have not ignored your advice, it is just if someone talks about soldering something to somewhere I get lost in space :doh:.

So just to get this right :scratch:. I could just use the signal from speaker cables(coming from Bastanis speaker terminals) to connect to the line level inputs of the sub amp when I insert a 1K ohm resitor?

Would this be any different compared to my current way of connecting the sub amp? Currently I am taking the signal from Bastanis speaker terminals, then using speaker cable I run the signal to the sub amp's speaker input connectors and from amps output connectors again using speaker cable to the sealed woofer. I will ad link which shows available connectors on the amp I am using.

http://www.audiosanctum.co.uk/Subwoofer-Amplifiers/XTZ-Sub-Amp-1-Subwoofer-Amplifier-Gloss-Black.html



I'm working from my phone so I've not fully digested the problem....but one route is to feed the bass amp from your amp outputs, with high efficiency speakers the speaker levels input on bass amps often are not the right level. You can get around this by inserting a 1k resistor in the cable from the amp speaker output and then take this to the LINE level input on the bass amp.

[Clive]

It is very similar. Often with 100db speakers the speaker level connection does not work well, there's not enough gain in the bass amps. If it works ok for you then probably the 1k resistor method will only be a little better. What is the problem with your existing connection?

BTW, if the interconnects are shorter coming from your integrated amp this could be better.

Out of interest what influenced you to get the Proms (really good speakers)?


Hello Clive.

Sorry I have not ignored your advice, it is just if someone talks about soldering something to somewhere I get lost in space :doh:.

So just to get this right :scratch:. I could just use the signal from speaker cables(coming from Bastanis speaker terminals) to connect to the line level inputs of the sub amp when I insert a 1K ohm resitor?

Would this be any different compared to my current way of connecting the sub amp? Currently I am taking the signal from Bastanis speaker terminals, then using speaker cable I run the signal to the sub amp's speaker input connectors and from amps output connectors again using speaker cable to the sealed woofer. I will ad link which shows available connectors on the amp I am using.

http://www.audiosanctum.co.uk/Subwoofer-Amplifiers/XTZ-Sub-Amp-1-Subwoofer-Amplifier-Gloss-Black.html

[The Grand Wazoo]

t seems the best solution would be to get separate preamp with two pair of outputs, one single ended and one balanced.

Oooooh! watch out for that one, if you decide to try it.
The gain is likely to be higher from the balanced outputs (I think)

[selfaddict]

Hello.

This is the exactly the problem I have. Currently I have only one Sub Amp and it does not have enough "grunt" to drive the 15" sealed woofers. I will buy another one when the funds allow. Currently I am using 2 meter speaker cables from Diavolo to Sub Amp and again 2 meter speaker cable from Sub Amp to the sealed woofers.

This was very useful information that using speaker cables the gain will be less compared to line level :youtheman:. I would like to position the Sub Amps behind the hifi rack and the speakers and by doing this keep the interconnects short.

The reason why I wanted to change my speakers(Dali Helicon 800) was that Diavolo did not have enough power to drive them as I wanted. I was actually looking to buy Horns, like Avantgarde, but this pair of Bastanis came to market and I was able to part exchange my Dalis for them,so it was no brainer :eyebrows:. I have to say that I do not need to go back to box speakers ever ever ever again :lol:


It is very similar. Often with 100db speakers the speaker level connection does not work well, there's not enough gain in the bass amps. If it works ok for you then probably the 1k resistor method will only be a little better. What is the problem with your existing connection?

BTW, if the interconnects are shorter coming from your integrated amp this could be better.

Out of interest what influenced you to get the Proms (really good speakers)?

[selfaddict]

This should not be a problem because Sub Amps will have volume adjustments built in them.

Juha


Oooooh! watch out for that one, if you decide to try it.
The gain is likely to be higher from the balanced outputs (I think)

[John]

Yes open baffles are very different to boxed speakers I could not imagine going back to normal speakers
The pre amp should work but might be worth seeing if you got someone nearby who can solder first

[Clive]

Hello.

This is the exactly the problem I have. Currently I have only one Sub Amp and it does not have enough "grunt" to drive the 15" sealed woofers. I will buy another one when the funds allow. Currently I am using 2 meter speaker cables from Diavolo to Sub Amp and again 2 meter speaker cable from Sub Amp to the sealed woofers.

This was very useful information that using speaker cables the gain will be less compared to line level :youtheman:. I would like to position the Sub Amps behind the hifi rack and the speakers and by doing this keep the interconnects short.

The reason why I wanted to change my speakers(Dali Helicon 800) was that Diavolo did not have enough power to drive them as I wanted. I was actually looking to buy Horns, like Avantgarde, but this pair of Bastanis came to market and I was able to part exchange my Dalis for them,so it was no brainer :eyebrows:. I have to say that I do not need to go back to box speakers ever ever ever again :lol:
I'm not 100% sure whether your problem is that the bass is not good enough quality with one bass amp or whether the bass is too quiet.

It your bass is too quiet (due to the signal to the speakers being low because they are high efficiency), then a preamp for line-level connection will work but a much cheaper option you must try is the 1k resistor. A 2nd bass amp would not help the quiet bass situation. What happens is that the speaker-level input attenuates the signal too much as it's expecting a much stronger signal for less efficient speakers.

All that's needed is a cable connecting to either you main amp outputs or your speakers, the other end of the cable should have a phono plug. Where cable enters the plug the positive wire should have a 1k resistor on the end of it, the other end of the resistor is soldered to the centre pin of the phono plug. You then connect to the line input at the bass amp. The 1k resistor does not need to be a big wattage, 0.5W or so will be fine.

Everytime you listen to box speakers now, you'll hear the box.....

[selfaddict]

The quality of the bass is the problem to me currently. These are my first pair of OB speakers, highs and mids and are just honey sweet, clear and without any discoloration. I am struggling to get same quality of bass unfortunately. I think part of the problem is room where speakers are located. Other reason will be that the woofers are quite new and not yet run in.

I do not know if the reason is that I am running both speakers(Bastanis and sealed woofers) from the same speaker tabs is something to do this? Then there is the fact that my speaker tabs at Diavolo are 6 Ohm, and the Gemini tweeter is running 16 Ohm and the full range driver at 8 Ohm. I am planning to add another full range driver so then the whole speaker is 16 Ohm for my understanding. Adding another full range driver should improve high bass as well and integrate the woofers better. So it is combination of all above I think :scratch:.


I'm not 100% sure whether your problem is that the bass is not good enough quality with one bass amp or whether the bass is too quiet.

It your bass is too quiet (due to the signal to the speakers being low because they are high efficiency), then a preamp for line-level connection will work but a much cheaper option you must try is the 1k resistor. A 2nd bass amp would not help the quiet bass situation. What happens is that the speaker-level input attenuates the signal too much as it's expecting a much stronger signal for less efficient speakers.

All that's needed is a cable connecting to either you main amp outputs or your speakers, the other end of the cable should have a phono plug. Where cable enters the plug the positive wire should have a 1k resistor on the end of it, the other end of the resistor is soldered to the centre pin of the phono plug. You then connect to the line input at the bass amp. The 1k resistor does not need to be a big wattage, 0.5W or so will be fine.

Everytime you listen to box speakers now, you'll hear the box.....

[John]

How far have you got your speakers from the rear wall, this effects bass quality on Open Baffles
If its bass quality might be room layout can you show us some pictures

[Clive]

I 2nd what John says, show us the room layout. I've have 12 inch sealed, 15 inch sealed and 18 inch dipoles along with both Prometheus and Atlas so I've had a good play with how the set up works.

If the woofer is quite new, have they had a loud session? They need this to get the surrounds to move otherwise they can remain too new (ie stiff). In my room I ended up with the basses against the back wall and the main baffles about 1m into the room.

1 bass amp works fine with 2 speakers, 2 amps are better but 1's ok.

My room is really dreadful for room modes as it is a square with a bay window added to it and it has a low ceiling (it's a cellar room). So I use the XTZs with DSP.

[selfaddict]

Hello John.

The Bastanis are 0.75m from the back wall and the sealed 15" woofers are 0.3m from the same wall. Baffles sits on the top of the woofers.

My room is tiny currently only 3.3m wide and 2.9m deep. My chair is next to the back wall and the distance from the speakers is 1.9m to my chair. Fortunately this arrangement is only temporary because we have accepted an offer on our house and now just waiting for the exchange of the contracts to make the deal official.

The room where my kit is heading to, once we move back to Finland, will be 4 meters wide and 5 meters deep with high ceiling height. I am planning to position the speakers one meter from the corners(width and depth) and sit as far back as possible from the speakers.






How far have you got your speakers from the rear wall, this effects bass quality on Open Baffles
If its bass quality might be room layout can you show us some pictures

[selfaddict]

Hello Clive.

The woofers are near new, ex demo pair actually, so I am sure they are very stiff still. Many thanks for recommending a loud session to loosen them up. I just found ICE T rap CD and turned the sub volume to max and turned both EQ1 and EQ2 on to increase 7db on 25Hz and 50Hz :eek:. I do not know how long I should use this set up because the user manual states:

Excessive use of EQ can lead to damage of the
subwoofer, when used at high volumes
EQ 2 and High Pass filter should not be used
at same time.



I 2nd what John says, show us the room layout. I've have 12 inch sealed, 15 inch sealed and 18 inch dipoles along with both Prometheus and Atlas so I've had a good play with how the set up works.

If the woofer is quite new, have they had a loud session? They need this to get the surrounds to move otherwise they can remain too new (ie stiff). In my room I ended up with the basses against the back wall and the main baffles about 1m into the room.

1 bass amp works fine with 2 speakers, 2 amps are better but 1's ok.

My room is really dreadful for room modes as it is a square with a bay window added to it and it has a low ceiling (it's a cellar room). So I use the XTZs with DSP.

[Reid Malenfant]

Hi Juha, i might have missed it but exactly what are these subwoofers that you have? I did look through the thread but didn't notice anything, no make or model :scratch:

[selfaddict]

Hello Mark.

I have only one XTZ Sub Amp 1, which is driving both 15" sealed woofers currently, but will buy second one when funds allow.

http://www.xtz.se/uk/products/electronics/sub-amp-1

Sorry just noticed that you asked about the subwoofers: They are the ones that Robert Bastanis uses currently in his sealed woofer cabinets. I am not 100% sure but I remember reading that they might be from XTZ as well.




Hi Juha, i might have missed it but exactly what are these subwoofers that you have? I did look through the thread but didn't notice anything, no make or model :scratch:

[Clive]

Hello Clive.

The woofers are near new, ex demo pair actually, so I am sure they are very stiff still. Many thanks for recommending a loud session to loosen them up. I just found ICE T rap CD and turned the sub volume to max and turned both EQ1 and EQ2 on to increase 7db on 25Hz and 50Hz :eek:. I do not know how long I should use this set up because the user manual states:

Excessive use of EQ can lead to damage of the
subwoofer, when used at high volumes
EQ 2 and High Pass filter should not be used
at same time.
Juha, it's shouldn't need much in the way of major excursions. Just a few mins at a time, maybe 4 or 5 times over a week.

[Clive]

Mark,

http://www.bastanis.de/kits_mandala.html#15baesse

[Reid Malenfant]

Hello Mark.

I have only one XTZ Sub Amp 1, which is driving both 15" sealed woofers currently, but will buy second one when funds allow.

http://www.xtz.se/uk/products/electronics/sub-amp-1
Ok, but what are the 15" drivers & did they come built into the sealed subs (new) or did you or someone else fit them into DIY or some other enclosures?

You are on about bass quality. It may well be that these subs have a high driver Q, i don't know what they are so can't comment, but i'm attempting to get to the bottom of it ;)

[Reid Malenfant]

Mark,

http://www.bastanis.de/kits_mandala.html#15baesse
:doh: Cheers Clive...

I'll assume they are reasonably well designed then... Scrub that train of thought :scratch:

[Clive]

Ok, but what are the 15" drivers & did they come built into the sealed subs (new) or did you or someone else fit them into DIY or some other enclosures?

You are on about bass quality. It may well be that these subs have a high driver Q, i don't know what they are so can't comment, but i'm attempting to get to the bottom of it ;)
I'm guessing these are a demo pair from http://www.audiosanctum.co.uk/Subwoofer-Amplifiers/XTZ-Sub-Amp-1-Subwoofer-Amplifier-Gloss-Black.html

in which case they were built by Bastanis woodworker so they'll be right.

Juha, is this correct?

[Clive]

:doh: Cheers Clive...

I'll assume they are reasonably well designed then... Scrub that train of thought :scratch:
You weren't to know Mark, it's sort of been half a discussion as I'm familiar with the speakers and amps.

I suspect there's just too much bass for such a small room. With the listening position at the back wall too....I bet there's room node there.

[selfaddict]

Hello Clive.

Actually I bought the whole set from Alium Audio at Brighton, which included original Robert Bastanis company built baffles etc.


I'm guessing these are a demo pair from http://www.audiosanctum.co.uk/Subwoofer-Amplifiers/XTZ-Sub-Amp-1-Subwoofer-Amplifier-Gloss-Black.html

in which case they were built by Bastanis woodworker so they'll be right.

Juha, is this correct?

[John]

I tend to agree with Clive I think the room size is over powering seeing that you moving soon I think its best to see what they are like in your new home but I suspect you notice a big improvement For the time being add some cusions in the corner soft furnishings may also help
It might be worth seeing if you can get a trade on the DSP subs but I wait till I move to the new house

[selfaddict]

Hello John and Clive.

I am also leaning toward that the room size is the cause of disintegration. Would any decoupling cones/spikes help to get the best of the speakers or would you use heavy marble added to cone/spikes under them? I am just thinking the future when they are in the room that they really deserve/need.



I tend to agree with Clive I think the room size is over powering seeing that you moving soon I think its best to see what they are like in your new home but I suspect you notice a big improvement For the time being add some cusions in the corner soft furnishings may also help
It might be worth seeing if you can get a trade on the DSP subs but I wait till I move to the new house

[Clive]

Juha, you'll be fine when you get the kit to Finland. A 2nd Swedish XTZ will improve the bass but not by a massive amount, one amp copes quite well. A 2nd amp also allows you to take the bass xover a little higher without it messing with the soundstage. I xver mine at 82Hz with a 12db/octave slope. I don't know what the slope is on the non-DSP amps

In the unlikely event you struggle with room modes in Finland you could add a Behringer DEQ2496 but you'd need to connect at line level via the method I suggested previously. I reckon you'll be ok.

[Clive]

Hello John and Clive.

I am also leaning toward that the room size is the cause of disintegration. Would any decoupling cones/spikes help to get the best of the speakers or would you use heavy marble added to cone/spikes under them? I am just thinking the future when they are in the room that they really deserve/need.
Juha,

Here's how my dipoles are set up:
http://i43.photobucket.com/albums/e359/cmeakins/1003200007.jpg

Nothing fancy is needed, I have simple rubber feet under the bass units. The open baffles sit on felt pads.

[John]

Decoupling might help Its worth a try