My New Setup

Yeahhh! Awesome Let me know when your room is ready Sorry I couldn't come by earlier

Dont worry..I am sure we all know how you feel !! Congratulation

surrealistix schrieb:

Shindo Auriges with Phono and Usher R 1.5 poweramp If I sound like a big show off - sorry can't help it, feel like shouting from the top of the mountain.

Nice Pre - What speakers do you use ?
Congratulations !!

I would love to come for a listen ?
Which city are you in ?

When ever you are ready - please do let me know, I shall as per your conveniance....
Thanks,

surrealistix schrieb:

I just upgraded my Pre-Power to Shindo Auriges with Phono and Usher R 1.5 poweramp I am also upgrading to a dedicated listening room The combo sounds really good with my Usher BE-718. I can't stop them goose bumps, listening to music I have heard so many times before! Once my listening room is ready everyone is invited!! If I sound like a big show off - sorry can't help it, feel like shouting from the top of the mountain.

Great feeling Buddy.... !!!
So what did you upgrade from, what was your previous setup ?
I have heard the BE-718 with the Usher amp...good combo.

Congrats - surrealistix

Stay with the feeling and ENJOY !

Hello and congratulations and thankyou for your invite. Could you please tell me where you are located?

The BE-718 and Usher R 1.5 poweramp are made for each other
Shindo makes some awesome gear. Someone I know recently listened to the Shindo field coil speakers with an all Shindo gear and was blown away.He was telling me about some of the hi-end gear people bring in for trade in when they go for Shindo.
Great going. Have fun.
Try out the Usher cables also if you can. They are made by the same OEM who makes cables for acoustic zen. They are supposed to be great match with the Usher amp/speaker combo.

I have tried the Usher ICs and Speaker cables....dissapointed!!

They are detailed but very colored in the mids. Especially due to the Silver strands they are highly screechy and bright on the vocals. Try them out if you want but do also keep a decent copper cable with you for reference..especially try out female vocals. Just my 0.0002.

I have just tried out their top of the line Interconnect. Have not tried out the speaker cables.
Out of the box I didn’t quite like it. I let it burn in for 100 hours and sounded quite ok. The difference before and after burn in was quite a bit. But I was not fully satisfied with them in my system.
Another friend of mine with the Green mountain audio EOS2 tried out the burned in interconnect and he liked them a lot. From what I heard, it goes quite good with the Ushers.
I suggested these because they have been voiced with the ushers.

Thank you everyone.

I am pleased as punch with my new setup. The Shindo was not even in my short list till the last moment.

The Shindo dealer in Singapore brought a Shindo Vostro Romanee preamp home for a listen, we switched from his Mark Levinson Ref 32 to the Shindo and it was sounding much better.

The nesxt day, Sridhar from ARN wrote to me recommending the Shindo, so I gave the Aurieges a try - stretched my budget considerably and bought it immediately :-)

Zhopudey, Bhagwan, Switch-It-On - I live on Palm Beach road in Navi Mumbai. Once my room is ready, I will let you know.

The Usher BE-718 speakers, Usher R 1.5 amp and the Shindo Aurieges pre sound fantastic together.

I am using an Odeon Lite Dac for the past few years now and quite happy with the sound.

Thanks for the advice on Interconnects and Speaker cables, Sridhar will be sending me some speaker cables and Interconnects to try.

I am currently using QED Silver Anniversary speaker cables, Clear Audio Silver Interconnect, and another MIT interconnect (not sure which one).

I also got Shakti stone, VPI brick, and Ayre Martel blocks - hand me down from my brother - will play around with these tweaks once it's all setup.

Need some help with acoustics - will ask questions on a seperate post.




I live on Palm Beach Road in Navi Mumbai. My room should be ready in the next 15 days.

I am us

surrealistix schrieb:

I also got Shakti stone, VPI brick, and Ayre Martel blocks - hand me down from my brother -

Do let us know about your adventures with these....

surrealistix schrieb:

Zhopudey, Bhagwan, Switch-It-On - I live on Palm Beach road in Navi Mumbai. Once my room is ready, I will let you know. I live on Palm Beach Road in Navi Mumbai. My room should be ready in the next 15 days. I am us

It shall be my pleasure to visit you;
I stay in South Bombay;
However any Saturday should be a nice day.
You get your set up 'in place' & fully functional.
We will drive to you - spend a few hours - listen to some music - play around with some cables & take it from there.

Thanks,

p.s. I have some cables from Hungary - Solitone -
I would like for you to 'audition it' in your house !!!
I will get a set along....

I finally have my dedicated listening room.

I still have to get the bass traps and absorption panels in place, replace sliding windows with soundproof windows and the last quote of paint.

I am planning to do all that after I have spent a month or so listening to music in the room.

Here is a pic of my work in progress room - I have too many things between the two speakers which need to go some place else in the room.

Ronnie,
That’s too many things between your speakers
One suggestion. Move all the stuff that’s related to home theatre to a rack on your side wall. Fix the centre speaker to the wall beneath the screen. Then have a simple rack holding the two channel gear between your speakers.

Square Wave, that's pretty much what I plan to do.

Great... It will improve the imaging big time.

On a different note, What is the output imprdence of the shindo preamp in kohms ?

I am not sure about the output impedence. I usually listen to it between 25% to 40% of the volume knob.

Okay.
I got this information from a review of the Aurieges-L line stage. You have the Aurieges right ?
Specifications:

Type: Line stage non-Negative-Feedback preamplifier
Tubes: 2 x ECL86, 1 x 12AX7
Inputs: CD, FM, AUX, TV (RCA Pin Jack)
Input impedance: 100KΩ
Output (RCA Pin Jack) impedance: 10V/5KΩ
Signal to Noise Ratio: 120 dB. Non NFB
Frequency Response: 10 - 50,000 Hz
Power Requirements: 120V,220V - 230 V, 50/60 Hz
Power consumption: 50 W
Dimensions: W 11 x H 3 x D 12 inches
Weight: 9lb

You typically need 1:10 difference between the output impedence of the preamp and the input imput impedence of the power amplifier. The more the better. The preamp seems to have a fairly high output impedance of 5 kohm.
What is the input impedence of the Usher amp ?

I would read that as 5kohms at 10v output, isn't that how it should be read ? Viren ? Siva ? Ampnut ?

I had the same dilema reading the spec of the jolida cdp.
what freq was this impedance measured ? 1khz ? Doesn't impedance increase with rising freq ?

I don't know if stereophile has reviewed this preamp but they do measure the output impedances of preamps at various freq's under various load conditions and get down to telling us what HF roll off can we expect.

Manek

Manek schrieb:

I would read that as 5kohms at 10v output, isn't that how it should be read ? Viren ? Siva ? Ampnut ? I had the same dilema reading the spec of the jolida cdp. what freq was this impedance measured ? 1khz ? Doesn't impedance increase with rising freq ? I don't know if stereophile has reviewed this preamp but they do measure the output impedances of preamps at various freq's under various load conditions and get down to telling us what HF roll off can we expect. Manek

Aare Manek dikra, you fell for it again!
Just like the Jolida 100 CDP that you were considering once upon a time, this preamp o/p impedance spec seems to say that the NEXT stage input impedance should NOT drop below 5K Ohms (otherwise it'll load down the preamp o/p stage).

If the manuf made a preamp w/ a 5K Ohm o/p impedance then I think he should pay us money to buy his preamp!
I'm quite certain that the 5K Ohms relates to the next stage input impedance.
Others can comment on this if they think I'm wrong.

surrealistix schrieb:

I finally have my dedicated listening room. I still have to get the bass traps and absorption panels in place, replace sliding windows with soundproof windows and the last quote of paint. I am planning to do all that after I have spent a month or so listening to music in the room. Here is a pic of my work in progress room - I have too many things between the two speakers which need to go some place else in the room.

nice room, surrealistix.
Is that room of yours real OR surreal??
Or, does it feel surreal to finally have your dedicated listening room?

bombaywalla schrieb:

this preamp o/p impedance spec seems to say that the NEXT stage input impedance should NOT drop below 5K Ohms (otherwise it'll load down the preamp o/p stage). If the manuf made a preamp w/ a 5K Ohm o/p impedance then I think he should pay us money to buy his preamp! I'm quite certain that the 5K Ohms relates to the next stage input impedance. Others can comment on this if they think I'm wrong.

Taking a look at the range of Power amps from Shindo Labs, their lowest inp imp starts off at 100K while most of the lot are 250K. Hence, 5K o/p imp Pre --> 100/250K Pwr seems OK !! provided the users are gonna mate with Shindo power amps.....

The excellent Hovland Pre HP-100/200 have a single-ended o/p imp of 2.5K while their Sapphire Pwr amp's inp imp is 680K. So, they work w/o probs.

Unfortunately, Usher do not mention the inp imp of their R1.5 power amp hence we don't know whats going on here between the Shindo-Usher when it boils down to electrical integrity. Generally, 1:20 is the min acceptable.

Bombaywallah

Thanks for reminding me. I had actually forgotten this conversation we had earlier. Will also lookup your emails.
No offence meant.

So what we deduce is if manufacturer specs xxxohms, xxvolts he is referring to the next stage min cut off input impedance ? And when he specs
just xxx ohms it would mean the output impedance of the amp ?

Manek

audio_engr schrieb:

bombaywalla schrieb: this preamp o/p impedance spec seems to say that the NEXT stage input impedance should NOT drop below 5K Ohms (otherwise it'll load down the preamp o/p stage). If the manuf made a preamp w/ a 5K Ohm o/p impedance then I think he should pay us money to buy his preamp! I'm quite certain that the 5K Ohms relates to the next stage input impedance. Others can comment on this if they think I'm wrong. Taking a look at the range of Power amps from Shindo Labs, their lowest inp imp starts off at 100K while most of the lot are 250K. Hence, 5K o/p imp Pre --> 100/250K Pwr seems OK !! provided the users are gonna mate with Shindo power amps..... The excellent Hovland Pre HP-100/200 have a single-ended o/p imp of 2.5K while their Sapphire Pwr amp's inp imp is 680K. So, they work w/o probs. Unfortunately, Usher do not mention the inp imp of their R1.5 power amp hence we don't know whats going on here between the Shindo-Usher when it boils down to electrical integrity. Generally, 1:20 is the min acceptable. :)

well, it seems that I've learnt something new re. tube preamp outputs.
I didn't think that 5K-Ohms for a tube pre was a good sign given that my experience has been otherwise. Some of the tube preamps that I've been exposed to recently such as the CAT SL1 XXX have 100 Ohms o/p impedance, the Audio Note (UK) M2B has 20 Ohms o/p impedance, the ARC Ref 3 has 600 Ohms o/p impedance, the ARC SP-6A has something similar. Hence I was quite sure that the 5 K-Ohms must be relating to the next stage inp. impedance. Looks like I could have been wrong.....
No problem.

Folks
I have tried the Shindo Aurieges Pre with the Odyssey amp (Input Z of 11K) and the Usher R1.5 with input Z of 47K ohms. They both played extremely well with no problem in drive. Yes like many of you, I was worried about the 1:5 to 1:10 rule but found absolutely nothing lacking. Both combo's as Surrealistix can probably add were really good. Shindo labs advised not to use their pres with any device less than 5K ohms (obvious). Their higher end pre's have an output Z of 600 ohms.
I believe Sterophile has reviewed this pre along with their other pres

cheers

Bombaywalla

My original question still remains....if the amps show an output imp of say 2kohms...measured at what freq ? Cause the output imp won't stay constant across the freq range....and when imp climbs that's when roll off occurs

Someboby pls throw some light on whether my assumption is right.

Manek

surrealistix schrieb:

I finally have my dedicated listening room. I still have to get the bass traps and absorption panels in place, replace sliding windows with soundproof windows and the last quote of paint. I am planning to do all that after I have spent a month or so listening to music in the room. Here is a pic of my work in progress room - I have too many things between the two speakers which need to go some place else in the room.

Lucky man....thats a lovely room. I envy you..

redwine schrieb:

Folks I have tried the Shindo Aurieges Pre with the Odyssey amp (Input Z of 11K) and the Usher R1.5 with input Z of 47K ohms. They both played extremely well with no problem in drive. Yes like many of you, I was worried about the 1:5 to 1:10 rule but found absolutely nothing lacking. Both combo's as Surrealistix can probably add were really good. Shindo labs advised not to use their pres with any device less than 5K ohms (obvious). Their higher end pre's have an output Z of 600 ohms. I believe Sterophile has reviewed this pre along with their other pres cheers

Isn’t the odyssey amp’s 11khm too less for the Shindo preamp? We are looking at a 1:2 difference here. Anything higher that 5k ohm will work technically but sound quality ?
The 47kohm of the Usher seems good. I was worried about the 11k ohm when I bought the odyssey but siva’s preamp which I use has a very low output impedance of 150 ohms so I am looking at a 1:70 difference here

Bombaywalla: I had to convert my four bedroom apartment to a two bedroom apartment to make this room happen. So it's Surreal and it's real! Finally!!

Listening to music in this room makes the music timeless. By that I mean, time seems to slow down or lose meaning. There is no need to hurry or worry, just sit and enjoy.

I am not sure if there is an impedance mismatch between the Shindo and the Usher amp, or the Shindo and the Stratos. To me they both sound very good and at typical listening levels the volume knob is well below half way.

I would think that if there is an impedance mismatch, it would be immediately apparent in terms of boomy bass and generally muddy sound. Neither of the two combos display any such characteristic.

Is there some very specific nature of sound degradation cause due to impedance mismatch?

I am waiting for my Amp and Pre to get sold so I can splurge some more on cables and room acoustics 

redwine schrieb:

Folks I have tried the Shindo Aurieges Pre with the Odyssey amp (Input Z of 11K) and the Usher R1.5 with input Z of 47K ohms. They both played extremely well with no problem in drive. Yes like many of you, I was worried about the 1:5 to 1:10 rule but found absolutely nothing lacking. Both combo's as Surrealistix can probably add were really good. Shindo labs advised not to use their pres with any device less than 5K ohms (obvious). Their higher end pre's have an output Z of 600 ohms. I believe Sterophile has reviewed this pre along with their other pres cheers

When the ratio of o/p imp ---> inp imp is small, i.e. less than 1:10, rarely do you see problems in drive etc. What you do see is "narrowing of the soundstage width", esp as the volume is raised up more & more.... Immediately change one of the components & get this ratio well over 1:20, you'll immediately notice wall-to-wall width is restored in your soundstage.

When the ratio of o/p imp ---> inp imp is small, i.e. less than 1:10, rarely do you see problems in drive etc. What you do see is "narrowing of the soundstage width", esp as the volume is raised up more & more.... Immediately change one of the components & get this ratio well over 1:20, you'll immediately notice wall-to-wall width is restored in your soundstage.

Interesting observation.

I thought that a wide soundstage was primarily dependent on Loudspeaker's ability to image well ( eg Low relative phase shifts is often attributed to this ) and ofcourse the Room acoustics, particularly the behaviour of the surface behind the speakers and the first reflection points....

On the other hand...
Some HiFi designers such as Mark Levinson ( when he launched his Viola product range ) ensured a VERY High Input impedance of 500K Ohms to 1000 K Ohms for every stage in the system, including the Volume control and internal inter-stage coupling. Ofcourse this was at the cost of increased noise... those bloody inflexible laws of Physics

Bombaywalla said:

I didn't think that 5K-Ohms for a tube pre was a good sign

Actually, Valve Preamps, always have to grapple with less than desirable output impedance. Valves just cant do it..... UNLESS

1. High levels of negative feedback are used. This is a No-No in modern day audio ckt design.

OR

2. Parallel Output Valves are used ( I think the ACT-2 does that .. ?

Ofcourse, if the Valve pre is pushed to drive a less than easy load, distortion usually rises... but most Valve generated distortion is a comfortable sounding even harmonic distortion ( 2nd, 4th etc ), so the Valve pre can aquit itself pretty well.

As Manek Points out : the input and output impedances BOTH vary with frequency, particularly at the frequency extremes.

A deep Bass roll off could occur, but if the speakers anyway dont extend below 30 Hz ( VERY few do ! ) it will hardly be noticed.

An extreme High Freq roll off, could be audible, but in some systems, produce a preferred sound...

( Remember Bland-N-Dul Cables ? Jest Kidding )


Then ofcourse there is the major issue of the listner's preferred sound.. His foucus may be on Imaging, or tone, or musical and involving presentation... rather than accuracy or frequency extremes.

In the final analysis, its whether the Pre-Power combination, delivers the buyer, what he cherishes the most.

I believe surrealistix is delighted with his system.

In the sense of a ratio, yes its 1:2. The Candela to Stratos is 1:10 you have heard both the Candela and your pre with the Odyssey side by side with a 1:10 vs 1:70, did you find one lacking wrt to the other, I dont think so, yes, we didnt study this for hours but anything apparent and we would have heard it. As they say, the proof is in the pudding...

cheers
Sridhar

square_wave schrieb:

redwine schrieb: Folks I have tried the Shindo Aurieges Pre with the Odyssey amp (Input Z of 11K) and the Usher R1.5 with input Z of 47K ohms. They both played extremely well with no problem in drive. Yes like many of you, I was worried about the 1:5 to 1:10 rule but found absolutely nothing lacking. Both combo's as Surrealistix can probably add were really good. Shindo labs advised not to use their pres with any device less than 5K ohms (obvious). Their higher end pre's have an output Z of 600 ohms. I believe Sterophile has reviewed this pre along with their other pres cheers Isn’t the odyssey amp’s 11khm too less for the Shindo preamp? We are looking at a 1:2 difference here. Anything higher that 5k ohm will work technically but sound quality ? The 47kohm of the Usher seems good. I was worried about the 11k ohm when I bought the odyssey but siva’s preamp which I use has a very low output impedance of 150 ohms so I am looking at a 1:70 difference here :D

Amp_Nut schrieb:

Bombaywalla said: I didn't think that 5K-Ohms for a tube pre was a good sign Actually, Valve Preamps, always have to grapple with less than desirable output impedance. Valves just cant do it..... UNLESS 1. High levels of negative feedback are used. This is a No-No in modern day audio ckt design. OR 2. Parallel Output Valves are used ( I think the ACT-2 does that .. ? Ofcourse, if the Valve pre is pushed to drive a less than easy load, distortion usually rises... but most Valve generated distortion is a comfortable sounding even harmonic distortion ( 2nd, 4th etc ), so the Valve pre can aquit itself pretty well. As Manek Points out : the input and output impedances BOTH vary with frequency, particularly at the frequency extremes. A deep Bass roll off could occur, but if the speakers anyway dont extend below 30 Hz ( VERY few do ! ) it will hardly be noticed. An extreme High Freq roll off, could be audible, but in some systems, produce a preferred sound... ( Remember Bland-N-Dul Cables ? Jest Kidding ) Then ofcourse there is the major issue of the listner's preferred sound.. His foucus may be on Imaging, or tone, or musical and involving presentation... rather than accuracy or frequency extremes. In the final analysis, its whether the Pre-Power combination, delivers the buyer, what he cherishes the most. I believe surrealistix is delighted with his system. :prost

Yup..........I have not heard anyone so happy with his system for a long time now..Cheers

redwine schrieb:

In the sense of a ratio, yes its 1:2. The Candela to Stratos is 1:10 you have heard both the Candela and your pre with the Odyssey side by side with a 1:10 vs 1:70, did you find one lacking wrt to the other, I dont think so, yes, we didnt study this for hours but anything apparent and we would have heard it. As they say, the proof is in the pudding... cheers Sridhar square_wave schrieb: redwine schrieb: Folks I have tried the Shindo Aurieges Pre with the Odyssey amp (Input Z of 11K) and the Usher R1.5 with input Z of 47K ohms. They both played extremely well with no problem in drive. Yes like many of you, I was worried about the 1:5 to 1:10 rule but found absolutely nothing lacking. Both combo's as Surrealistix can probably add were really good. Shindo labs advised not to use their pres with any device less than 5K ohms (obvious). Their higher end pre's have an output Z of 600 ohms. I believe Sterophile has reviewed this pre along with their other pres cheers Isn’t the odyssey amp’s 11khm too less for the Shindo preamp? We are looking at a 1:2 difference here. Anything higher that 5k ohm will work technically but sound quality ? The 47kohm of the Usher seems good. I was worried about the 11k ohm when I bought the odyssey but siva’s preamp which I use has a very low output impedance of 150 ohms so I am looking at a 1:70 difference here :D

I totally agree. They just worked fine
I am sure there are hundred other factors here which determines performance and stability

Manek schrieb:

Bombaywalla My original question still remains....if the amps show an output imp of say 2kohms...measured at what freq ? Cause the output imp won't stay constant across the freq range....and when imp climbs that's when roll off occurs Someboby pls throw some light on whether my assumption is right. Manek

Manek,
I was pulling your leg in the other post. I hope that you took that in the right spirit?

OK, now to your question: From talking to various manuf & to some of my hard-core DIY friends, usually the o/p impedance (that is stated as a single number on the spec sheet) is measured at 1KHz.
As you already know, the impedance & phase plots give the full picture.
You are correct, the impedance (& phase) does not remain constant over freq.
Indeed, per my experience, when input impedance increases that offending stage loads the stage before it in the signal chain & one gets roll-off, narrowing of the soundstage (as audio_engr wrote).
Also from my experience if the preamp has relatively high o/p impedance w.r.t the amp's inp impedance, one could also hear uncontrolled bass (as in too much bass overhang) & thin bass (as in not full/not fleshed out).

So ampnut would it not be nice if manufacturers published a min and max output impedance for a given load at a fixed frequency ? Currently I think the standard unofficially is 1khz but don't know at what load.


Secondly a ratio of 1:2 and the system working like a charm is very difficult to believe or the impedance figures are very conservative ?

Manek

Manek schrieb:

So ampnut would it not be nice if manufacturers published a min and max output impedance for a given load at a fixed frequency ? Currently I think the standard unofficially is 1khz but don't know at what load.

you are asking re. preamps, correct? if so, good question.
I didn't quite understand your question the 1st time I read it!
(for amps we know that it is 1KHz, 8 ohms).

Manek schrieb:

Secondly a ratio of 1:2 and the system working like a charm is very difficult to believe or the impedance figures are very conservative ? Manek

agree!

Yes bombaywalla

I do mean preamps, and maybe cdps ? Especially tube equipment.
For my own pre which has 600ohms output impedance - has written to dennis had and he categorically mentioned nothing less that 20kohms of input impedance. I tried with a 10k amp and sure enough there was high freq roll off.


Manek

For whatever its worth, I am reproducing below, the ( portions relevant to Input / Output Impedance ) Specs indicated in the Owners Manual, for my Audio Research LS26 Preamp. This is the Pre just below AR's current Top-of-The-Line, Ref-3.

I believe these are detailed enough to provide an insight into what should be used, and indications of where Performance Hits (in terms of objective measurements ) could occur.

Specifications Audio Research LS26

FREQUENCY RESPONSE: to-3dB, 0.2Hz to 16OkHz at
rated output (Balanced, 200k ohms load)

DISTORTION: Less than .01% at 2V RMS BAL output.


INPUT IMPEDANCE: 120K ohms Balanced, 60K ohms SE.
Inputs (8): Tuner, Phono, CD, Video, Aux 1, Aux 2, Monitor,
Processor (XLR and RCA connectors).

OUTPUT IMPEDANCE: 700 ohms Balanced, 350 ohms SE
Main (2),20K ohms minimum load and 2000pF maximum
capacitance.
Outputs (3): 2 Main, 1 Record (XLR and RCA
connectors).


RATED OUTPUTS: 2V RMS 1 Hz to 100kHz into 200K ohm
balanced load (maximum balanced output capability is 15V
RMS at less than 0.5% THD at 1 kHz).


Note that the 2000 Pf Capacitance itself will present a Load of 8K3 ( 8300 Ohms ) at 20 KHz.

Ampnut

Thanks for the spec sheet. It was far more revealing than others I have seen. This was kind of what I was thinking of, nice to know.

Manek

Nice layout surrealistix....enjoy..

Amp_Nut schrieb:

OUTPUT IMPEDANCE: 700 ohms Balanced, 350 ohms SE Main (2),20K ohms minimum load and 2000pF maximum capacitance. Outputs (3): 2 Main, 1 Record (XLR and RCA connectors). RATED OUTPUTS: 2V RMS 1 Hz to 100kHz into 200K ohm balanced load (maximum balanced output capability is 15V RMS at less than 0.5% THD at 1 kHz).

Thanx for sharing Amp_nut.
From Manek's perspective, the question remains - what under what load conditions did ARC measure an o/p impedance of 700 ohms Balanced, 350 ohms SE
Main (2)?
Was the LS26 unloaded?
If not, was the load 200KOhms (as was the case to measure a max o/p voltage of 2V RMS)?
Was the load less?

Also, interesting to note that the max voltage of 2V RMS was measured at 200KOHms load.
I *think* that there are hardly any power amps in the market that have 200KOhms input impedance??
Most amps that I know have 20KOhms - 50KOhms. Some older Threshold & maybe Forte designs were hard on the preamp as they had only 2KOhms input impedance!!
So, with a more real-world loading will the LS26 really put out 2V RMS?
I really do not think that it matters as the line signal will be high enough to stimulate the power amp. However, I was wondering why did ARC (and I'll extend it to other preamp manuf) not measure max o/p voltage at some real-world load numbers?
If the o/p voltage was measured at 200KOHms load, I wonder at what load the o/p impedance was measured?
Just to be clear: I'm NOT slamming ARC; I believe that this issue is endemic to the audio industry. Lots of reference to ARC due to Amp_Nut's posting the partial spec of the LS26.

Ok, let me post the FULL Specs as given in the User Manual.

I think there are some incorrect conclusions drwn from the limited specs that I posted,

Specifications AR LS26 PRE AMP

FREQUENCY RESPONSE:
to-3dB, 0.2Hz to 16OkHz at rated output (Balanced, 200k ohms load)

DISTORTION: Less than .01% at 2V RMS BAL output.
GAIN: Main output: Selectable for each input: 24dB, 1 BdB,
12dB Balanced output. (1 8dB, 12dB, 6dB SE output.)
Record output: OdB (Processor input: OdB balanced).

INPUT IMPEDANCE: 120K ohms Balanced, 60K ohms SE.
Inputs (8): Tuner, Phono, CD, Video, Aux 1, Aux 2, Monitor,
Processor (XLR and RCA connectors).

OUTPUT IMPEDANCE: 700 ohms Balanced, 350 ohms SE
Main (2),20K ohms minimum load and 2000pF maximum
capacitance. Outputs (3): 2 Main, 1 Record (XLR and RCA
connectors).

OUTPUT POLARITY: Non-inverting.

MAXIMUM INPUT: Low Gain: 48V RMS BAL, 24V RMS SE,
Medium Gain: 24V RMS BAL, 12V RMS SE, High Gain: 12V
RMS BAL, 6V RMS SE.

RATED OUTPUTS: 2V RMS 1 Hz to 100kHz into 200K ohm
balanced load (maximum balanced output capab~lityis 15V
RMS at less than 0.5% THD at 1 kHz).

CONTROLS: Rotary volume selector (1 04 steps) and
rotary input selector.

Push buttons: Power, Mono, BAUSE, Proc, Monitor, Mute.
Also remote buttons: Display, Bal L, Bal R, Hours, Invert, Gain.

POWER SUPPLIES: Electronically-regulated low and high
voltage supplies. Automatic 50 sec. warm-up/brown-out mute.
Line regulation better than .01%.

NOISE: 1.3uV RMS residual IHF weighted balanced equivalent
input noise with volume at 1 (1 00dB below 2V RMS output).

TUBE COMPLEMENT: 2-6H30P dual triode, (Hybrid
JFET/tube audio circuit, solid-state power supply.)

POWER REQUIREMENTS: 105-1 30VAC 60Hz (21 0-260VAC
50/60Hz) 50 watts maximum.

DIMENSIONS: 19" (48 cm) W x 5.25" (1 3.4 cm) H (standard rack panel) x 12" (30.5 cm) D. Handles extend 1.50" (3.8 cm) forward of the front panel.

WEIGHT: 16.5 Ibs. (7.5 kg) Net; 26 Ibs. (1 1.8 kg) Shipping.

Thanx for sharing Amp_nut. From Manek's perspective, the question remains - what under what load conditions did ARC measure an o/p impedance of 700 ohms Balanced, 350 ohms SE Main (2)? Was the LS26 unloaded?

Input impedance of a Pre amp is measured by varying the load resistor till the Output accross the external load is exactly 50% of the no load voltage. That is the output impedance.

The output Impedance therefore cannot be measured at No load / open circuit..


I think Manek's question, was "At What Frequency is the Output Impedance specified"

was the load 200KOhms (as was the case to measure a max o/p voltage of 2V RMS)?

2 Volts RMS is the Rated Output, not the Maximum Output !

Most Pre amps... Particularly Valve Pre amps will deliver a MAX output of around 8 to 16 Volts RMS... but will not meet distortion specs or drive low impedances at these Huge Output swings, which are generally of academic interest only.


Another point I want to make.... Often People think that VERY Long Balanced Interconnects can be used, with no performance hit.

While Valve Pres are less capable than their SS counterparts in low output impedance ( generally) note that the LS26 specifies a Max load capacitance of 2000 pf.

Interconnects have a capacitance of 500 pf to 100 pf per foot..

Hence 2000 pf would mean a total run of 20 feet ( approx 3 meters ) ... a fair practical limit, but not a Huge length...

I am posting on this thread after a long time. In the past three months, I built a whole bunch of acoustic panels for my AV room and also upgraded my cables, DAC and built a DIY Subwoofer.

I built 4 corner bass traps, 2 for the sides, 1 for the ceiling and 2 for the rear wall. The corner trap use 4 inches of mineral wool and 2 inches of glass wool. The rest of the traps use 4 inches of glass wool.

I got a Peter Daniel Nos DAC, upgraded my PC Sound Card to M-Audio Audiophile 192.

Got a bunch of new cables - Zu Wax Speaker Cables, Tekline Pur Silver RCA between the DAC and the Preamp

Built a huge ported Subwoofer primarily for Home theatre with Eminence Lab 12 driver and using a Tapco Juice 2500 pro audio amp

Phew… No more tweaking…it’s time to relax and enjoy. I am super pleased with my setup. Would love for some of the forum members to come home and check it out. Bhagwan69 and Zhopudey - Let me know if you guys can make it on the coming weekend. I would love if some more members from the forum came over as well.

Here are some updated pics:

Are you located in Mumbai ?

I would love to visit & listen.

Please check yr PM

Hi Amp Nut,

You are most welcome to drop by. I am on Palm Beach Road, Nerul, Navi Mumbai.

Thanks !