[marvda1]

i need to hear from anyone with experience with these amps.  i'm looking at the 45 watt version.
http://www.audiomirror.com/amps.html

thanks,
marvin

[FredT300B]

I'm using them with my Selah Audio XT-8 line arrays. I had hoped to take them to the LSAF but couldn't get them into the truck with the speakers occupying so much space, and I thought Vlad would be bringing a pair to demo. Too bad, you could have heard them there. Mine are the 40 watt version. Their appearance and sound is about what I would expect from a $4K pair of monoblocks, which is surprising because they cost less than half that amount. Two other Houston Audio Society members have bought them since I hosted a meeting at my house last year so other members could hear them. One of those members, our society president, whom you may have met at the fest, has also commissioned Jim Salk to design a pair of high efficiency speakers to use with them.

I'm not too good with reviewspeak, but I'll give it a try. They do have that sweet SET sound combined with the power needed to drive real world speakers, and they do nothing bad that I can hear. The bass is as tight as I have heard from a SET, but not as controlled as a good ss amp. The midrange is the typical SET audiophile's heaven. The treble is right - nice de-emphasis of siblants but definitely not recessed with percussion sounds. The only downside I have found with them is a well known charactersitic of the 6C33C tubes - they vary considerably, a few will not bias within the recommended 14-18 volt range, and the occasional tube failure after a few hours of use isn't uncommon. I've blown a couple of output tubes since I bought the amp, and Vlad has been very good about replacing them - after the second one blew he gave me two so I would have a spare on hand if another one failed. So far that hasn't happened.

Did you meet Tate (Custom Isolation Products) at the fest?  Here's a picture of one of my Audio Mirror amps sitting on his neon blue LED custom acrylic stands:
http://lonestarbottleheads.org/gallery/displayimage.php?album=32&pos=4

[marvda1]

yes i met Tate, the amp stands with frosted fronts capture the blue light much better.  Vlad put together a pair of his monoblocks (45 watts) Saturday night and finished them about 1:45 sunday afternoon.  he took them to Tate's room to hear them on the marten speakers (4 ohm, 89 db.) and compare them to the $7000+ art audio 80 watt monoblocks.  he cranked the volume pretty loud to try to get an idea how they would sound on my speakers (8 ohm, 87 db.).  in comparing them to the art audio the consensus opinion was the the audio mirror had better bass and the art's beat them out on soundstage size, dept and upper level finesse but remember the audio mirrors were only 3 hours old.  wish i could stay up all night and make something like those

[JoshK]

Doug S. also own these mono blocks.

A few quick notes about the 6C33C.  I am building a pair of monoblocks around them, so I've done a bit of digging on them.  As Fred said, they are prone to failures, fresh out of the box, as this is semi-typical of gassy low rp tubes.  However, this can be circumventing, by doing the proper burn in and prep procedure before plugging them into a circuit, and it what BAT, Tenor, LAMM and other manufacturers likely do to ensure the reliability of the amps they build with this tube.

Basically, you need to wire up the heaters and run them on a regulated heater supply for about 24 hours.  The easiest way to do this is to obtain a cheap surplus switching power supply with 6V and around 6A per tube (or 12V @ 3amps/tube, as they can be wired either way).  This supply should be current regulated, or at least voltage regulated with the appropriate o/c protection.  Most SMPS's have such built in.  Just wire up some sockets to the supply on a bench and run the tubes for many hours. 

After the heaters have been settled in, it would be a good idea to then bring the tubes up slowly to their operating points, but plugging the tubes into the circuit, but with a variac and brought up slowly (heaters would need to be independent of variac).  Then one could even apply a few test signals to run through paces.  This last paragraph not all reported to have done, but would probably be a good idea.  This ensures any gas is burned off and doesn't cause tube to run away, causing self destruction.  Once this is done though, the tubes should no longer have any problems with reliability.

[FredT300B]

Basically, you need to wire up the heaters and run them on a regulated heater supply for about 24 hours. 

Josh, how is this different from running them in the amp for 24 hours? Is the increased dependability a result of running them for an extended period with no B+ on the plates?

[doug s.]

yes,

josh is right; i have a pair of the older 40w wersions.  vlad has said they can be updated to sound like the new wersions w/a simple replacement of a couple caps in each amp.  he recommended i not trade mine in for the latest wersion, as i have already had them updated w/better transformers & top-of-amp bias settings.

the 6c33c tube issue is real, but these tubes are awailable relatively reasonably on ebay:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=300109022210

a while back, i took mine over to woodsyi's house to try them on the ribbons of his vmps rm40's, (from 280hz on up - rim uses solid state amps below 280hz on his rm40's).  they compared quite favorably to his response audio modded asl extreme hurricanes.  i think they are a freaking bargain, even at vlad's asking price for brand-new amps.  they have that excellent smooth tube sound & soundstaging, plenty of detail & dynamics, & have no problem driving real-world speaker loads.  i can't comment on their ability to do low bass, as i have always used mine crossed over to subs at ~60-80hz.  but, they're excellent from 80hz on up, as has been described above...

doug s.

[JoshK]

Basically, you need to wire up the heaters and run them on a regulated heater supply for about 24 hours. 

Josh, how is this different from running them in the amp for 24 hours? Is the increased dependability a result of running them for an extended period with no B+ on the plates?

Yes, the point is to not have B+ on the plate for the time you are burning them in, then when you bring on the B+, you do it slowly, raising it slowly.

[FredT300B]

Vlad is a low profile manufacturer, and his Audio Mirror isn't as well known as some high profile manufacturers like VTL, Audio Research, Manley, etc., but his product have much in common with them becuse they are hand-assembled in the US with point-to-point wiring. it's hard not to love them. 

http://www.audiomirror.com/images/vacuumtube6c33ca.html

[woodsyi]

yes,

josh is right; i have a pair of the older 40w wersions.  vlad has said they can be updated to sound like the new wersions w/a simple replacement of a couple caps in each amp.  he recommended i not trade mine in for the latest wersion, as i have already had them updated w/better transformers & top-of-amp bias settings.

the 6c33c tube issue is real, but these tubes are awailable relatively reasonably on ebay:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=300109022210

a while back, i took mine over to woodsyi's house to try them on the ribbons of his vmps rm40's, (from 280hz on up - rim uses solid state amps below 280hz on his rm40's).  they compared quite favorably to his response audio modded asl extreme hurricanes.  i think they are a freaking bargain, even at vlad's asking price for brand-new amps.  they have that excellent smooth tube sound & soundstaging, plenty of detail & dynamics, & have no problem driving real-world speaker loads.  i can't comment on their ability to do low bass, as i have always used mine crossed over to subs at ~60-80hz.  but, they're excellent from 80hz on up, as has been described above...

doug s.

They did sound good.  I remember doug mentioning some start up procedure that required warming up.  Of course he also had red base RCA driver tubes which may have contributed to the overall excellence.

[doug s.]

They did sound good.  I remember doug mentioning some start up procedure that required warming up.  Of course he also had red base RCA driver tubes which may have contributed to the overall excellence.

the amps i own just require yo turn them to standby for a couple of minutes before switching them on.  i dunno if the latest amps have this requirement.

yes, the driver tubes i have in them are some of the best, (if not the best?), imo - rca 5691's for the 6sl7's, & rca 5692's for the 6sn7's...

ymmv,

doug s.

[marvda1]

the latest ones have a slow start delay.  Doug s, do you have the 40 watt version or 45 watt version?
have you tried them with lower efficiency speakers?

[doug s.]

the latest ones have a slow start delay.  Doug s, do you have the 40 watt version or 45 watt version?
have you tried them with lower efficiency speakers?

mine are the 40w wersion, but i would have to ask vlad if the rating still holds, as the transformers were updated, & i understand that this is the main difference in the amp's power ratings.  the least efficient speakers i presently have now are 91db-efficient, i don't think this qualifies as low-efficiency speakers.     but, as i mentioned, i did try them w/the vmps rm40's, which like a lot of power, despite their 90db rating, & they were an excellent match.  but, as i said, they were only driving the midrange on up; the woofers being driven by solid-state amps.  this is how rim has his set-up; he uses the response-audio asl hurricanes on midrange/tweets...

doug s.