Completed Stereomour...Low Volume Issue

[M42]

Hi All,

I have completed my Stereomour but am experiencing a low volume issue with it. My resistance checks seemed within limits as did all the voltage checks except two. Terminal strip 5 should read 0 volts as per the manual. Mine reads 57.8 volts. Terminal 6 should read 60 volts...I have 0 volts at this point. One note, I had a difficult time getting all the ground leads from the volume pot  through terminal 8L. After checking the forum I did as another builder did and moved the ground bus that connects B9 to 10L. I don't know if this might be a contributing factor, but I suspect not.

Being impatient, I hooked the amp up after the resistance checks. At virtually full volume the amp was generating a very low volume level. I wired the OT's for 4 ohms. My speakers are 8 ohms.  Any advice would be greatly appreciated.

Thanks,

Jeff

 

[Paul Birkeland]

Hmm, looks like some manual editing moved some voltages around.

T5 should be ~60V, T6 is grounded, so 0V is appropriate.

What source are you using to feed the amp? 

How are your OA/OB voltages?

 

[M42]

Hi Paul,

OA voltage is 210.8 and OB reads 224.4. I'm running my Reduction amp into the Stereomour with my Thorens turntable and Grace ruby F8 cart.

Jeff

 

[Doc B]

I can't find an output spec for the F8 ruby, but the F9 ruby is rated at 3.5mV which is a little on the low side. That could be part of the problem.

 

[M42]

Hi Doc,

I have an old CD player...I'll see if anything changes with that as a source.

 

[Doc B]

That is a very logical plan. What speakers are you using? If you rewire the amp for 8 ohms output you will get a little bit higher level out of the speakers at a given volume setting.

 

[M42]

That seems to be the issue Doc, I'm getting more volume (gain?) with the CD player. The knob is still at the three o'clock position for a "reasonable" listening level. Looks like I built it right the first time! Time to trim the hum pots and figure out what to do about my vinyl setup. I am using NST Super Zero 2.1 speakers....amazing little speakers.

Jeff

 

[Paul Birkeland]

The Integration will bump the gain of the Reduction up a big, but a cartridge that's more around 5-6mV will help a lot too.

 

[M42]

Thanks Paul,

I'll order the Integration, hopefully it will resolve the issue. I'm particularly fond of Grace carts...I'm about to acquire an F9! Thanks again for your help.

Jeff

 

[fullheadofnothing]

87dB speakers aren't helping the situation much either...

 

[M42]

Hi Josh,

Point taken...and quite right, Orcas are waiting in the wings. Unfortunately they'll have to wait a while longer.

 

[Doc B]

When I was looking for specs it seemed that some variants of the F9 were rated 5.5mV and some were rated 3.5mV. Might want to check the spec of the one you are looking at.

 

[M42]

Doc, both the Grace F8 and F9E carts are 3.5mV. Would the some 4 db gain of the Integration make a significant difference in your estimation, or would the Eros be the ultimate cure (more efficient speakers aside)?

 

[Paul Birkeland]

You're going to want the Eros for that, 3.5mV is certainly on the low side for a moving magnet cartridge. 

 

[Paul Joppa]

Hi Josh,

Point taken...and quite right, Orcas are waiting in the wings. Unfortunately they'll have to wait a while longer.

Orcas are similar sensitivity. They may sound better at these lower levels, but they are not more efficient.

 

[M42]

I revisited the specs for the Orcas, I thought I had read they were more efficient than they are. I will likely replace my Reduction with the Eros, I want to keep the Grace carts. I have a very small listening room ( 8 x10' ) so I'm hoping to find some suitable speakers. I wasn't considering building some, but it sounds like there are some good diy designs out there.

 

[Paul Birkeland]

Yeah, there are kind of a few dimensions to what you need to consider.

The most important thing (in my opinion) is to be able to get all the power out of the Stereomour that it can offer with the sources that you have.  If you're leaving 2-3 Watts on the table because the source voltage is too low, then changing to more sensitive speakers doesn't really address the core problem.

On the other hand, if you find yourself bottoming out the speakers, or clipping the amplifier, then more power or speakers of higher sensitivity would be worth looking into.