Early 70's Concert vs. Red Knob Concert

[Walt-Dogg]

Any tonal differences between the early 70s Concert lead and the Red Knob Concert Lead? I'm looking into picking up an early 70s Concert Lead just wanna know what to expect. Also is an early 70s Concert Bass the same as a Red knob Concert Bass?

[rot gut]

I have a red knobbed one that I'm thinking of selling if you're interested.

[django7866]

The earlier 70's concert lead had 2 channels both had brite and normal inputs. Channel one had distortion and channel 2 had reverb. I think the red knob just had brite and normal switch but had a switch to flip between brite and normal.  the One thing that is really cool about the early 70's leads is you could jump the two channels by using a instrument cable. You can't do that with the red knob ones. Has far as tone is concerned I never had the chance to play a red knob one. The concert bass series the only 2 differences I could see is that the early 70's bass had distortion and was rated to 4 ohms minimal load and the red knob did not have distortion and was rated at 2 ohms minimal load. There are also some boost switches can't remember if both had them. Hope that is some help.

[Walt-Dogg]

rot gut, I'm looking for an early 70s I already have a red knob Concert Lead and Bass.

django, not much more than I already knew, but I didn't know there was distortion on early 70's Concert Basses, which is interesting since there's only the schematic for what I think to be early 70s Concert Bass on the site. Which creates a problem for me since I'm looking to start a project in which I basically copy the boost circuit out of my red knob Concert Lead and turn it into a pedal to use in conjunction with my red knob Concert Bass and in order to do that I need find any differences in the tone stacks in each amp otherwise there's no way it will sound the same as it does when I use my Concert Lead as a bass amp with the boost circuit on.

Still wanna know about the tonal differences between the two models of Concert Leads

[george]

Both designs have FET inputs, interstage transformers and 2N3055 in a quasi complementray output section. I do not see how there is a major "tonal" difference between the two series of amps. I have three versions of the Concert Bass and do not see any major difference. I have gone through all three amps and tested them for power output, distortion and frequency response.

BTW the later version ("red knob") is not reliable when using sub 4 ohm loads. 

[biltmore]

BTW the later version ("red knob") is not reliable when using sub 4 ohm loads.

Say what?! Really?

[NsubUlysses]

So can the early version Concert Lead play at 2 ohms? I thought 4 was the minimum.

[django7866]

So can the early version Concert Lead play at 2 ohms? I thought 4 was the minimum.

The early versions were rated at 4Ohm Minimal load The red Knobs were rated at 2Ohms minimal load. I have heard that the red knobs would burn out if used below 4ohms. Actually read that somewhere on  a bunch of times on different thread through out this forum.

[biltmore]

I have heard that the red knobs would burn out if used below 4ohms. Actually read that somewhere on  a bunch of times on different thread through out this forum.

And that's just on the Concert's, and not the Coliseum's?

[django7866]

I have heard that the red knobs would burn out if used below 4ohms. Actually read that somewhere on  a bunch of times on different thread through out this forum.

And that's just on the Concert's, and not the Coliseum's?

I have not read that about the coliseums, I have never used a coliseum series amp of any kind so I really don't have knowledge on those.

[Isaac]

IIRC, the Coliseum power section had several more output devices than the Concert power section did. Sunn ads and promo material at the time clearly stated that the Coliseum amps were stable down to 2 ohms, and I have never heard or read anyone question that claim. My conclusion? Keep Concert loads at 4 ohms or above, and go down to 2 ohms with Coliseum amps with no worries.