Where's an AMPEG TECH...?

[Son of Bovril]

I got a good idea that I think bass amp designers should consider for a high end-amp:

Lets take an Eden WT-800 or an AMPEG SVT4-PRO
(it has to be a bi-amp type amp)

Now lets take the one power amp out and replace it with a tube version of the same/similar power.

Now we use the bi-amp function to send the High frequencies to the tube power section and the lows to the SS section. Now let us mono bridge that into 4 ohms!

Has no one thought of doing this in a single head or have I just been blindfolded?

 

[i_got_a_mohawk]

you saying a tube and an SS power amp section in the same amp

I dont know but i think there are alot of inherant problems with that, just due to the nature of how the valves work, im quite possibly wrong tho (and i dont think it would be any more that 300 watt in the tube section)

 

[Son of Bovril]

Yeah, thats what I'm talking about - A bi-amp system with one half being tube...

the tube section wouldn't even have to be that powerful, as it would only be handling the highs, which don't require that much power to push. The SS section could be quite big though to push the lows and get a nice punchy bottom end...

You'd have to build in a variable crossover and a blend control for the two to really be able adjust your sound.

I'm not a tech unfortunately (otherwise I'd build it myself!), so I wouldn't know what inherent problems are involved? Have any anp companies attempted this before?

 

[alexclaber]

I got a good idea that I think bass amp designers should consider for a high end-amp:

Lets take an Eden WT-800 or an AMPEG SVT4-PRO
(it has to be a bi-amp type amp)

Now lets take the one power amp out and replace it with a tube version of the same/similar power.

Now we use the bi-amp function to send the High frequencies to the tube power section and the lows to the SS section. Now let us mono bridge that into 4 ohms!

Has no one thought of doing this in a single head or have I just been blindfolded?

Well you can't bridge two different amps across each other, especially if they're running different frequency ranges. Plus, a 400W tube power stage would be huge and heavy. But to evolve the concept:

All tube preamp -> active crossover (@~500Hz?); highs -> 100W tube power stage, lows -> 1000W solidstate power stage. Matching cabs would be a 10" driver in compact sealed box for mids/highs, with additional 5" high mid driver and quality tweeter (both attenuatable depending on vintageness required) and 15" driver in larger ported box to handle all the lows and low mids.

So with cunning design the head would weigh about as much as a old Bassman head + a Stewart 1.2 power amp, whilst the cabs would come in around 35lbs for the high box and 50lbs for the low (assuming light ply, cunning bracing and neo drivers).

Alex

 

[Son of Bovril]

yeah, I see what yo mean about the bridging problem...

I'm not sure how bridging works exactly, but I'm sure something could be worked out... hmmm...

how could we recombine the frequencies post power amps?

 

[alexclaber]

yeah, I see what yo mean about the bridging problem...

I'm not sure how bridging works exactly, but I'm sure something could be worked out... hmmm...

how could we recombine the frequencies post power amps?

Bridging works by inverting the output of one amp so instead both amps pushing two loads separately, they both can act on a single load, with one amp pushing and the other pulling. For this to work, the amps have to have matching gain and power output.

The only way to recombine the frequencies AFAIK is to drive separate speakers and let the sound re-join in the air.

Rather than having two separate cabs, you could use a single cab with dual inputs, like the discontinued Ampeg 1x18"+2x10"+2x6"+horn cab. Or use an El Whappo with a redesigned crossover.

Alex

 

[Son of Bovril]

So there is no way to kinda reverse a crossover to re-combine the two signals?

 

[Mark Reccord]

Biamp would be the only possible way to go.

It's being done but not in bass amps.

Our flagship Hifi system uses a pair of 100W solid state amps to drive a pair of 10" woofers and four 5W, 300B tube amps to drive the mids and tweeters using electronic crossovers for frequency division. I'm not sure if it's the only one out there but there's a reasonable chance it is.

 

[basstrader]

So there is no way to kinda reverse a crossover to re-combine the two signals?

You could do it but it would defeat the whole purpose. You would have to take the two high power sections and run them through some kind of common amp to the output. Any kind of thing that would be able to take that much power would be a design feat in itself, and then the output would be either a solid state or tube amp covering the whole range. Letting the acoustic signal combine in the air is free and automatic.

 

[throbgod13]

use a preamp..

send the frequencies out to a parametric eq (unless the preamp already bi-amps, then you don't need a parametric eq)..

send the high/mids to a tube power amp.. and the lows to a solild state poweramp..

the only thing is to find a tube poweramp.. i'm sure that you can find one that would fit your needs, as you won't need huge amount of power for the high/mids.. 20-50 watts..

 

[basstrader]

use a preamp..

send the frequencies out to a parametric eq (unless the preamp already bi-amps, then you don't need a parametric eq)..

send the high/mids to a tube power amp.. and the lows to a solild state poweramp..

the only thing is to find a tube poweramp.. i'm sure that you can find one that would fit your needs, as you won't need huge amount of power for the high/mids.. 20-50 watts..

Carvin has a tube power amp
TS100

100 watts should do fine for the high end. Add a DCM1500 or any other SS amp of your liking, and you'd be cooking. Using an all tube preamp with a crossover would be ideal I would think.

 

[Joe P]

...It's being done but not in bass amps.

Our flagship Hifi system uses a pair of 100W solid state amps to drive a pair of 10" woofers and four 5W, 300B tube amps to drive the mids and tweeters using electronic crossovers for frequency division...

I chuckled and thought of you as soon as I read the opening post, Mark!

~~~~~~~~~~~~~~~~~~
Some of you guys (not Mark, surely) may be surprised to find how little power is needed for highs. I put together a system once for guitar that sounded absolutely killer; it was biamped, and used a couple-hundred-watt S.S. 1X15 bass combo amp for the lows, and a modded and cranked Fender Champ for the highs. The champ distorted on it's own, so you could run an OD pedal to get distortion overall, with more from the champ, or run clean lows with tube-distorted highs - that sounded pretty cool. I don't remember what crossover freq I used... Dang.. I don't think it was very high - something like 4-500Hz or something? It was very loud and full - but even though a small-small amount of the total power emminated from the Champ, it was surprizing how 'quiet' it got if you switched the champ out of the system!

Joe