Lower volume with 610T's

brad225 · Sep 6, 2015

I have what I think is an abnormal issue and need some others thoughts.

I purchased a pair of 610T's to replace my VTM200's. They came from a dealer and were unopened from ARC after having some circuitry upgrades and a couple of resisters replaced after a tube arc took them out. The service department went through them and they were retubed. When I spoke with Kalvin at ARC he stated these were as close to new as they could possibly get.

I installed them yesterday and they sound amazing. I'm currently using them with a Ref 3, Sony SCD1 with 6+ balanced upgrade from Vacuum State, Martin Logan CLSIIz's and 4 Depth i Subs in a dedicated room.

Both the 610's and the VTM200's have an input of 200k Ohms. The Ref 3 has an balanced output of 20k Ohms.

My issue is that the 610T's have about 15% less volume than the VTM 200's at the same settings on the Ref 3.

Is there anything you can think of that would make this happen.

I spoke with the Dealer and he wants to have a conference call with Kalvin this week to try to figure it out.

microstrip · Sep 6, 2015

brad225 said:
I have what I think is an abnormal issue and need some others thoughts.

I purchased a pair of 610T's to replace my VTM200's. They came from a dealer and were unopened from ARC after having some circuitry upgrades and a couple of resisters replaced after a tube arc took them out. The service department went through them and they were retubed. When I spoke with Kalvin at ARC he stated these were as close to new as they could possibly get.

I installed them yesterday and they sound amazing. I'm currently using them with a Ref 3, Sony SCD1 with 6+ balanced upgrade from Vacuum State, Martin Logan CLSIIz's and 4 Depth i Subs in a dedicated room.

Both the 610's and the VTM200's have an input of 200k Ohms. The Ref 3 has an balanced output of 20k Ohms.

My issue is that the 610T's have about 15% less volume than the VTM 200's at the same settings on the Ref 3.

Is there anything you can think of that would make this happen.

I spoke with the Dealer and he wants to have a conference call with Kalvin this week to try to figure it out.

It is written in the specifications - the 610T have 24 dB gain and the VTM200 have 27 dB. For equivalent sound volume you must set the preamplifier at a volume 3 dB higher in the preamplifier when using the REF610T. It is normal and a good thing - enjoy your excellent amplifiers. BTW the balanced output of the REF3 has 600 ohm output impedance.

For any information on old Audio Research equipment we can consult the AR database site: http://www.arcdb.ws/

brad225 · Sep 7, 2015

Thanks for the reply.
So based on the information I supplied the 3db difference in the 610t's would account for previously listing to the 200's at a volume number of say 70 and now on the 610t's I need to turn the volume up to 80-82 for the same volume. The volume I listen at is one that you can have a conversation over the music with slightly raised voices.

Here is where I guess I fall into the (Another person that doesn't understand electronics category) with my thinking. I figured that I would probably have 10-20% more volume with that increase in power. Oh well, time to crack open some more web pages and get some more knowledge.

number95 · Sep 14, 2015

brad225 said:
Thanks for the reply.
So based on the information I supplied the 3db difference in the 610t's would account for previously listing to the 200's at a volume number of say 70 and now on the 610t's I need to turn the volume up to 80-82 for the same volume. The volume I listen at is one that you can have a conversation over the music with slightly raised voices.

Here is where I guess I fall into the (Another person that doesn't understand electronics category) with my thinking. I figured that I would probably have 10-20% more volume with that increase in power. Oh well, time to crack open some more web pages and get some more knowledge.

Think of gain as instantenous amplification factor for the signal coming thru the power amplifier. Consider the power rating of the power amplifier as maximum power it can deliver to speakers without clipping. Ref 610 has much more power compared to VM220 though its gain is lower.

number95 · Sep 14, 2015

Btw, enjoy your Ref 610Ts , I love them!

Which 6550 tubes are you having with your 610Ts ?

brad225 · Sep 14, 2015

Thanks 95,
The 610's came to me from ARC after inspection. They changed some of the start up circuits, replaced any caps, resistors or diodes that didn't preform to specs. Cleaned and adjusted tube sockets and new tubes.

number95 · Sep 14, 2015

I am currently using Sovtek 6550we after years of using SED 6550 winged c, I was curious before replacing them as SED being discontinued, so far I am amazed with these new Sovtek 6550.

Frank750 · Sep 14, 2015

number95 said:
I am currently using Sovtek 6550we after years of using SED 6550 winged c, I was curious before replacing them as SED being discontinued, so far I am amazed with these new Sovtek 6550.

I was told by a tube vendor, who has stock on the SED 6550 winged C by the way, that the stock he had was not reliable and he would prefer to sell me the Sovteks at a cheaper price.

brad225 · Sep 14, 2015

I am sure with my next tube purchase It will be Sovtek.

number95 · Sep 14, 2015

Frank750 said:
I was told by a tube vendor, who has stock on the SED 6550 winged C by the way, that the stock he had was not reliable and he would prefer to sell me the Sovteks at a cheaper price.

Hi Frank,

I have a similar experience! Unfortunately I bought a set of Nos status SED and results were pretty poor, I lost 2-3 tubes within a month while most of them seemed to be unmatched after a bit of usage. I then ordered Sovtek from ARC, they were precisely matched with very little variance and so far I had no tube faults. Apart from superior reliability, the sonic performance is also excellent.

microstrip · Sep 14, 2015

number95 said:
Hi Frank,

I have a similar experience! Unfortunately I bought a set of Nos status SED and results were pretty poor, I lost 2-3 tubes within a month while most of them seemed to be unmatched after a bit of usage. I then ordered Sovtek from ARC, they were precisely matched with very little variance and so far I had no tube faults. Apart from superior reliability, the sonic performance is also excellent.

Did you consider switching to the KT120's?

number95 · Sep 14, 2015

microstrip said:
Did you consider switching to the KT120's?

I considered that. I was told they are not drop in replacements for 6550 and amplifier needs to be modified within factory. I contacted to ARC a while ago but was told they have stopped modifying 610T for kt120. That is weird as an owner of 610Ts I am forced to keep them with 6550 or sell them for either kt120 or kt150. Anyway, they sound marvelous so that does not bother me currently.

brad225 · Sep 14, 2015

I asked Kalvin about the change to KT120's and he said they stopped the upgrade. He told me that the $7000 cost was just to high. You would think if someone was willing to spend the money they would perform the upgrade. I doubt I would put another $7000 into the 610 though.

Barry · Sep 14, 2015

I have over 60 SED Winged C 6550's that I have purchased from various sources over the past 5 years and have compared them sonically to the Sovtek 6550 WE's, admittedly in a preamp (ARC REF 40 Anniversary). I prefer the Winged C's. To me, they're a little more natural in this application versus the WE's which are on the analytical side. I think the preamp represents a more critical and revealing sonic test than the power amp, but you're free to draw your own conclusions in your system.

Echoing Number95's comments regarding the reliability, all my SED Winged C's that have all been tested on an Amplitrex AT-1000. I would advise not purchasing any of the most currently available 2011 NOS stock as they are much more likely to test well below average for both plate current and trans-conductance based on my measurements. I have had several that have "gassed out" (low to no vacuum) for pairs after I purchased them. I was warned as much by one of my US suppliers. I have also had a more difficult time matching these tubes within a 5% tolerance for iP and GMas well ( I actually match within 2% since I'm obsessive compulsive). 2006 and earlier date codes seem ok, but you've got a lot of tubes to replace! I can confirm that ARC generally does do a great job on matching so they are worth the extra price if that matters to you.

wsill · Sep 18, 2015

Diffs VTM200 vs Ref610

Brad225,

Can you tell me the primary differences you have experienced from the vtm 200 to the Ref 610's ?
I have contemplated each of these amps for my system going back and forth in my mind but not having 1st hand experience with either.

I have Wilson X-1 V5's, I used ARC ref 210 for a short time, didn't like them that much; I am now using Levinson #23 which sounds good.
But I realize the Levinson #23 is aging, the X-1's show all deficiencies.

Thanks,
Bill

number95 · Sep 19, 2015

wsill said:
Brad225,

Can you tell me the primary differences you have experienced from the vtm 200 to the Ref 610's ?
I have contemplated each of these amps for my system going back and forth in my mind but not having 1st hand experience with either.

I have Wilson X-1 V5's, I used ARC ref 210 for a short time, didn't like them that much; I am now using Levinson #23 which sounds good.
But I realize the Levinson #23 is aging, the X-1's show all deficiencies.

Thanks,
Bill

Well I have had a similar move, used to upgrade from VT200 to Ref 610Ts. Ref 610Ts are not comparable to VT or VTM, it is totally a different league.

microstrip · Sep 22, 2015

Barry said:
I have over 60 SED Winged C 6550's that I have purchased from various sources over the past 5 years and have compared them sonically to the Sovtek 6550 WE's, admittedly in a preamp (ARC REF 40 Anniversary). I prefer the Winged C's. To me, they're a little more natural in this application versus the WE's which are on the analytical side. I think the preamp represents a more critical and revealing sonic test than the power amp, but you're free to draw your own conclusions in your system.

(...)

The 6550 is used in the REF40 as a series element of the voltage regulator - I am not sure that we can extrapolate sonic qualities from the preamplifier to power amplifiers. And yes, I expect that its use in this function in the preamplifier is more critical than in the power amplifier. I also use Winged C's in my REF40.

brad225 · Oct 6, 2015

Bill,
Sorry I had not seen you responce. The VTM 200's are a great amp. Very clean and clear. Large deep sound stage. Precise image with specific placement of insturments and voices. In comparison the 610T's are just more refined in all ways. I'm not sorry in any way I purchased the 610's but I am not sure I wouldn't have been happy with the VTM200's once I receive my new player and solve my lack of voltage with the front end. I will try both any way.

brad225 · Jan 7, 2016

To finish off the topic. The modded Sony's low voltage output was the issue. The PlayBack Designs MPS-5 not only solved the problem of volume but is an amazing piece of equipment.

Lower volume with 610T's

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