Which amps work well with VSA?

Delacroix · « **Reply #60 on:** 3 Feb 2009, 12:58 am »

Agree on the nod for Nuforce -- I've their new 8.5v2 stereo amp in the house and it's amazing what an amp this small can do with the Vons. I'll have to take a pic of this amp trussed up with my Virtual Dynamics cables, they nearly lift the little amp up into the air. I imagine the monos must be even better....review forthcoming.

disco · « **Reply #61 on:** 3 Feb 2009, 02:36 am »

Dartzeel, Dartzeel, Dartzeel. In case you were wondering I really like and use the Dartzeel with my 9's

JackD201 · « **Reply #62 on:** 3 Feb 2009, 03:53 am »

VTL Siegfried in triode mode with a client's 9s is awesome too. Hey Disco, when are you gonna get your hands on Herve's new Mono Blocks

Where's Dimfer? I heard the TRODT 6c33 push pulls kick @ss with the 5 Anniversaries. Where are your impressions and pics man?

disco · « **Reply #63 on:** 3 Feb 2009, 04:31 am »

Dartzeel mono blocks

I want them

Dimfer · « **Reply #64 on:** 3 Feb 2009, 05:03 am »

I have VR5 Anniversary - on rotation are Lamm Reference 1.2 and Trodt 6c33c-b monoblocs. With the Lamm, you will enjoy total control and ease. The systems exudes timbral rightness - neither warm nor exceedingly lush. My Trodt 6c33c-b amps puts out approximately 25 in parallel SET mode and drives the VR5 to very loud level without a hint of glare. Obvious SET magic (with balls) - instruments are more delineated and you will hear a lot of inner detail. I hope I could say this without taking anything away from Lamm Ref 1.2 (I am ready to live with this pair for the rest of my life) - but in the early stage after I replaced the Lamm with Trodt, I was pleasantly surprised how much more detail the VR5 revealed. When I switch the Trodt to push/pull mode (approx 75 watts), you will notice more control in bass but the details in the mids and highs are somewhat diminished.

I really love how correct the Lamm Ref 1.2/VR5 does the vocals in recordings like Lizz Wright's The Orchard or Shelby Lynne's Just A Little Lovin'

I've heard most VD cables from the Judge (which never came to production I think),Genesis, Revelation etc extensively, but I am happily using VD Nite 3.0 - it was the highest model VD cable that's not cryoed when I purchased it 2 years ago. While the cryoed model are more detailed/dynamic, I find the Nite more musical and unfatiguing (it could be just me, of course) for long listening sessions. I think the VR5 & VD Nite 3.0 has good synergy.

The VR5 replaced an unknown but awesome pair (Accentus A101) in my main system. The A101 has a 150mm & 130 mm ribbon tweeter like that of VR9, so, you know what I mean.

Yes Jack, the VR5 & Trodt combo can kick some serious ass, I think.

JackD201 · « **Reply #65 on:** 3 Feb 2009, 12:57 pm »

Hey dimfer, there you are! I was thinking of giving Trodt a boost at this years show by loaning them a pair of speakers and perhaps a source. I might even sponsor their room. They deserve some exposure and I'm feeling generous.

Delacroix,

If you can pry these amps from dimfer's warm living fingers, I submit it should be a candidate for review at affordableaudio.com. That is if affordable audio accepts reviews of commissioned rather than lot or mass produced products. I've heard these amps driving LSA2 towers and I can attest to their very high value (performance/price ratio). These amps use tubes in the driver stage that are readily available but not commonly used.

For the record I am in no way associated with Trodt audio.

Delacroix · « **Reply #66 on:** 3 Feb 2009, 06:11 pm »

Quote from: JackD201 on 3 Feb 2009, 12:57 pm

Delacroix,

If you can pry these amps from dimfer's warm living fingers, I submit it should be a candidate for review at affordableaudio.com. That is if affordable audio accepts reviews of commissioned rather than lot or mass produced products. I've heard these amps driving LSA2 towers and I can attest to their very high value (performance/price ratio). These amps use tubes in the driver stage that are readily available but not commonly used.

For the record I am in no way associated with Trodt audio.

Hi, I've never heard of these amps but they do sound and look interesting. I'd love to take them on for a review for A$$Audio but many times companies that build in small batches just don't have the capacity to send pieces out, there's a paying customer waiting impatiently. Certainly the magazine would welcome them, I'll see what I can find out.

Best

jab · « **Reply #67 on:** 3 Feb 2009, 09:55 pm »

Tube Newbie, how do you like the Memory Player? Stand alone transport or w/dac? Jack B

Dimfer · « **Reply #68 on:** 4 Feb 2009, 04:07 am »

Quote from: jab on 3 Feb 2009, 09:55 pm

Tube Newbie, how do you like the Memory Player? Stand alone transport or w/dac? Jack B

No turning back, I really like it. Transport only and waiting for the availability of Nova Physics 32 bit tube dac - which will available as a user installable upgrade kit for the transport owners. Currently using with MBL 5011.

Dimfer · « **Reply #69 on:** 4 Feb 2009, 04:12 am »

Quote from: Delacroix on 3 Feb 2009, 06:11 pm

Hi, I've never heard of these amps but they do sound and look interesting. I'd love to take them on for a review for A$$Audio but many times companies that build in small batches just don't have the capacity to send pieces out, there's a paying customer waiting impatiently. Certainly the magazine would welcome them, I'll see what I can find out.

Best

hi Delacroix,

I would love to send my unit to you for review, maybe later in the year. I had been contacted by a fellow from the Canadian side of Stereo Mojo for review and personal audition, we'll see how it works out . Where are you located?

Delacroix · « **Reply #70 on:** 4 Feb 2009, 04:28 am »

Am in Austin TX...pm sent!

jab · « **Reply #71 on:** 5 Feb 2009, 04:39 pm »

Tube Newbie,, My MP is both transport and dac (I think it was the 2nd one built-I was an early convert after speaking with Clemont Perry from Stereo Times at CES a couple of yrs ago). Good things coming from Nova Physics that has/will set the audiophile world on fire. The MP is in a world all its own. Mated with any of Albert VS's designs and you've got the most accurate and faithful music playback system made. Jack

Dimfer · « **Reply #72 on:** 6 Feb 2009, 04:42 am »

yes Jack, the VR5, Lamm Ref 1.2 and NPMP is an awesome combination. I am really glad this is the path I chose when I did a system overhaul last summer.

Unfortunately, there are some NPMP non-believers, and most of the vocal ones never heard them. You are lucky to get one with the DAC so early, I'd been bugging Al Rohde & Mark Porzilli for the DAC for my unit, hopefully soon.

Dr. M · « **Reply #73 on:** 23 Mar 2009, 05:54 pm »

This is my first post here. I just found about this forum which is great news.

I own a VR-4SR Mark II speakers and they are powered by a pair of NAGRA Pyramids Monoblocks Amplifiers (200 watts each). the speakers sound great but at high volumes the amplifiers clip and shut down (no distortion though). I believe the low impedance of the bass drivers is too much for the NAGRA amps to handle.

I am thinking of getting a more powerful amp/amps for the bass modules and use the NAGRAs for the midrange/tweeters. I just can't figure what kind of amp i need and what would be a good impedance match for the NAGRA. The pre-amp is an Audio Research LS-26.

bentknee · « **Reply #74 on:** 23 Mar 2009, 06:37 pm »

Welcome DR M. I also have the SR's and run them with a 16 watt Art Audio Carissa and a 50 watt Mark Levinson ML 11. I have had no problems like you describe. I don't know how loud you are actually playing your system but the bass unit in the SR is a smooth 4 ohm load which should not be a problem for a 200 watt amp. I have been wrong before and will be wrong again but I think the amp needs to be checked first. The Nagra amps are not cheep and should be able to power a 92db speaker to very loud levels. See what some of the other guys think.

Blessings, Bob

es347 · « **Reply #75 on:** 23 Mar 2009, 06:53 pm »

Quote from: Dr. M on 23 Mar 2009, 05:54 pm

This is my first post here. I just found about this forum which is great news.

I own a VR-4SR Mark II speakers and they are powered by a pair of NAGRA Pyramids Monoblocks Amplifiers (200 watts each). the speakers sound great but at high volumes the amplifiers clip and shut down (no distortion though). I believe the low impedance of the bass drivers is too much for the NAGRA amps to handle.

I am thinking of getting a more powerful amp/amps for the bass modules and use the NAGRAs for the midrange/tweeters. I just can't figure what kind of amp i need and what would be a good impedance match for the NAGRA. The pre-amp is an Audio Research LS-26.

Hello Dr. M..

If your amps are actually clipping you will have very audible distortion. A guitar amplifier which is designed to produce distortion and does so by pumping out square waves (clipped sine waves). Sounds like your Nagras have a protection circuit that's misbehaving. You might call the mfr. and see what he thinks. Good luck. By the way, I also own the VR4 SR MKIIs and drive them with MC501 monoblocks. Those little bones in my inner ears will fracture long before the 501s start to clip

Dr. M · « **Reply #76 on:** 23 Mar 2009, 11:02 pm »

Maybe I used the word clipping wrong. The Nagra amps have a red light that goes on when the load is high and eventually shut down for protection. That is what I am experiencing when the loudness is above 100 dB at 3 meters. I originally got the 100 w/ch Nagra stereo power amp (PSA) and it was shutting down at high volumes. I did upgrade to the monoblocks and got similar results but at a higher volume. I did exchange one of the Nagara monoblocks just to make sure it was not defective but still get the same thing.

So the Nagra amp can drive the VS-VR4S Mark II to loud levels to a limit. They then shut down for protection (before any distortion is heard). Maybe I am driving the amps too much. I know my speakers are rated up to 500 watts. I heard these speakers need very powerful amps to shine. For normal to high listening volume, I have no problems.

JackD201 · « **Reply #77 on:** 23 Mar 2009, 11:41 pm »

Quote from: Dr. M on 23 Mar 2009, 05:54 pm

This is my first post here. I just found about this forum which is great news.

I own a VR-4SR Mark II speakers and they are powered by a pair of NAGRA Pyramids Monoblocks Amplifiers (200 watts each). the speakers sound great but at high volumes the amplifiers clip and shut down (no distortion though). I believe the low impedance of the bass drivers is too much for the NAGRA amps to handle.

I am thinking of getting a more powerful amp/amps for the bass modules and use the NAGRAs for the midrange/tweeters. I just can't figure what kind of amp i need and what would be a good impedance match for the NAGRA. The pre-amp is an Audio Research LS-26.

Hi Dr.M,

The Nagras should be able to drive anything louder than anybody would actually want including loudspeakers that dip briefly below 2 ohms which your SRs do not. The most common problems between tube preamps and solid state amps in general are potential impedance mismatches. This may not be your problem but I have a nagging feeling that there might be an impedance mismatch between your LS-26 which has an output impedance of 700ohms (XLR) and your Nagra which has a 100kohm input impedance. Out of curiosity, are you running balanced or single -ended? If you are running balanced then there is a chance you are experiencing a mismatch. The single ended outputs rated at 350ohms should be a better match. I haven't used Nagra's high-fi gear but have worked countless hours with Nagra recorders. Their inputs are "picky" for lack of a better word.

As far as I know the Nagra's protection circuit is activated when there is DC leakage (could be a bad tube or tubes are not yet in a state of thermal stability) or when they are running too hot (overdriven either by an input signal too hot or too heavy a speaker load). There are some things you might want to verify. I'll put it in a list just so it's neater.

1. The Nagra is internally switchable between 1v and 2v inputs. If you listen primarily to Digital then 2V should be the default setting.

2. The ARC LS-26 has adjustable Gain settings from 6db to the mid twenties. If you're maxed out or close to maxed out it could make your amp's input stage clip especially if your amps are set at 1V. You might want to throttle back the gain before cranking them back up. Never mind if the volume numerical display will show a much higher number than you're accustomed to since it is just a relative number. For as long as there's no distortion you're golden.

3. Try the single ended inputs in case the problem is in the impedance matching which could also clip the amp's input stage.

4. Wait at least 45 minutes before cranking the preamp to avoid the risk or DC leakage due to thermal instability.

5. It could also be a thermal problem. Your amps might be better off in a cooler location (away from heaters) or in spots with better ventilation.

6. I saved this for last. According to friends that design amplifiers, extending bass lower than 20Hz in amplifiers takes a power penalty. In this case the amps might really find the speakers a difficult load as you suspect.

In the end If you have another preamp around (preferably a solid state one) you might want to check if the amps protect at the same SPL. If they do then we can rule out the preamp as the problem. If they don't then we might have found the right starting point and run through Nos 1 to 4.

Good Luck!

JackD

Dr. M · « **Reply #78 on:** 24 Mar 2009, 01:40 am »

Hi JackD

Thanks for the detailed response.

I am using XLR connection from the ARC LS-26 to the Nagra (Nordost Tyr)

The Nagras sensibility is set at 1 v

The LS-26 gain is set at Hi for CD (Ayre C-5xe, XLR, Nordost Heimdall) and Low for phono (ARC PH7, RCA, Nordost Heimdall)
I don't think I have any thermal issues. The amps never run hot.

The Nagras will shut down if 1) Clipping occurs where the current on the output is more than 12A peak or if the tension is above 60 V peak or 2) In case of a short-circuit on the speaker connections (1 second) or 3) DC protection when a DC component > than +/- 2.5 V appears on the output of the Nagra Pyramid. The Nagra has also a thermal protection circuit.

So one of the above is occuring. I suspect number 1 above.

I'll experiment with different loads and wires (XLR vs single ended).

Thanks again.

es347 · « **Reply #79 on:** 24 Mar 2009, 02:26 am »

Quote from: JackD201 on 23 Mar 2009, 11:41 pm

Quote from: Dr. M on 23 Mar 2009, 05:54 pm
This is my first post here. I just found about this forum which is great news.

I own a VR-4SR Mark II speakers and they are powered by a pair of NAGRA Pyramids Monoblocks Amplifiers (200 watts each). the speakers sound great but at high volumes the amplifiers clip and shut down (no distortion though). I believe the low impedance of the bass drivers is too much for the NAGRA amps to handle.

I am thinking of getting a more powerful amp/amps for the bass modules and use the NAGRAs for the midrange/tweeters. I just can't figure what kind of amp i need and what would be a good impedance match for the NAGRA. The pre-amp is an Audio Research LS-26.

Hi Dr.M,

The Nagras should be able to drive anything louder than anybody would actually want including loudspeakers that dip briefly below 2 ohms which your SRs do not. The most common problems between tube preamps and solid state amps in general are potential impedance mismatches. This may not be your problem but I have a nagging feeling that there might be an impedance mismatch between your LS-26 which has an output impedance of 700ohms (XLR) and your Nagra which has a 100kohm input impedance. Out of curiosity, are you running balanced or single -ended? If you are running balanced then there is a chance you are experiencing a mismatch. The single ended outputs rated at 350ohms should be a better match. I haven't used Nagra's high-fi gear but have worked countless hours with Nagra recorders. Their inputs are "picky" for lack of a better word.

As far as I know the Nagra's protection circuit is activated when there is DC leakage (could be a bad tube or tubes are not yet in a state of thermal stability) or when they are running too hot (overdriven either by an input signal too hot or too heavy a speaker load). There are some things you might want to verify. I'll put it in a list just so it's neater.

1. The Nagra is internally switchable between 1v and 2v inputs. If you listen primarily to Digital then 2V should be the default setting.

2. The ARC LS-26 has adjustable Gain settings from 6db to the mid twenties. If you're maxed out or close to maxed out it could make your amp's input stage clip especially if your amps are set at 1V. You might want to throttle back the gain before cranking them back up. Never mind if the volume numerical display will show a much higher number than you're accustomed to since it is just a relative number. For as long as there's no distortion you're golden.

3. Try the single ended inputs in case the problem is in the impedance matching which could also clip the amp's input stage.

4. Wait at least 45 minutes before cranking the preamp to avoid the risk or DC leakage due to thermal instability.

5. It could also be a thermal problem. Your amps might be better off in a cooler location (away from heaters) or in spots with better ventilation.

6. I saved this for last. According to friends that design amplifiers, extending bass lower than 20Hz in amplifiers takes a power penalty. In this case the amps might really find the speakers a difficult load as you suspect.

In the end If you have another preamp around (preferably a solid state one) you might want to check if the amps protect at the same SPL. If they do then we can rule out the preamp as the problem. If they don't then we might have found the right starting point and run through Nos 1 to 4.

Good Luck!

JackD

Well done Jack. Not a bad synopsis for a senator.