[quietdragon]

I'm looking around for an older 4B, and I'm a little confused about the presence/absence of the per-channel gain controls.

Looking at some of the older 4B circuit diagrams I see the presence of a 20k log pot per channel which I think is used to adjust the channel gain.

Some of the pictures of older 4Bs show a clean face plate with no obvious sign of any channel gain adjustment controls.

I've perused some of the old manuals, and they don't seem to mention the gain adjustment at all. Am I looking at the wrong manuals?

Do some older 4Bs have internal channel gain control adjustments which are not externally accessible?

Which 4Bs have externally accessible gain control adjustments?

[James Tanner]

I'm looking around for an older 4B, and I'm a little confused about the presence/absence of the per-channel gain controls.

Looking at some of the older 4B circuit diagrams I see the presence of a 20k log pot per channel which I think is used to adjust the channel gain.

Some of the pictures of older 4Bs show a clean face plate with no obvious sign of any channel gain adjustment controls.

I've perused some of the old manuals, and they don't seem to mention the gain adjustment at all. Am I looking at the wrong manuals?

Do some older 4Bs have internal channel gain control adjustments which are not externally accessible?

Which 4Bs have externally accessible gain control adjustments?

Hi,

The gain controls were standard on the PRO versions of the 4B's but not the Consumer versions.  Some depending on the vintage where controlled from the rear panel and some from the front panel.

james

[quietdragon]

Some depending on the vintage where controlled from the rear panel and some from the front panel.

Am I correct in saying that if there are no external gain controls on either the front or the back panel, there are also no internal gain controls either?

[James Tanner]

Am I correct in saying that if there are no external gain controls on either the front or the back panel, there are also no internal gain controls either?

Hard to say because we have done many 'custom' units over the years.  You would have to remove the top to be sure.

james

[Mad Mr H]

If it is of any help,

On the older "ST" series the "PRO" units would usually have been in 19 inch rack format and the word "BRYSTON" was large across the front,

On the domestic units the Bryston logo was much smaller.

It is of course possible to have a 19 inch domestic non gain unit as well.



Could I ask why you need the gain control?

Maybe there is another option/way to achieve what you are looking to do......

[Mad Mr H]

the "gain" control if on the front was I think towards the upper left .

It is in the top "CREASE" line on the facia.

PLEASE NOTE : This is NOT a volume control like your normal amplifier.

The pot is about 3mm in diameter and is NOT obvious......

so you need to be real close to see it or know what you are looking for.

Just in case you are looking for "volume knobs that are usually very obvious !!!

[quietdragon]

Could I ask why you need the gain control?

I believe I might need gain adjustment to ensure each  pair of amps (bass vs treble) is balanced for each side (left vs right). Right?

[quietdragon]

Hard to say because we have done many 'custom' units over the years.  You would have to remove the top to be sure.

Ok, so if I remove the top, can you give any guidance as to what am I looking for?

[James Tanner]

Ok, so if I remove the top, can you give any guidance as to what am I looking for?

Hi,

Give me the serial number of the amp and I should be able to tell you if it has gain controls or not - I assume your buying used?

james

[Mad Mr H]

I believe I might need gain adjustment to ensure each  pair of amps (bass vs treble) is balanced for each side (left vs right). Right?

The way round that is to use the amps in a horizontal bi amp configuration.

One amp does bass, one mid/hi.

vertical bi amp would use one amp per side.


to put this in real terms when my 14B SST was tested I think A+B ch were about 2 or 3 watts different, in 600+ w

about as close as it gets.


If you vertical bi amp you could use the balance control to even any gain issue.

To be honest I would build the system THEN work out what to do IF there are any issues.......Or you can spend all your time thinking about issues that dont appear........