That elusive "perfect" bass tone

[CL400Peavey]

It's an AWESOME amp -- and now I need to go sell some things...

Sell me a Max bass preamp and foot switch... You wont need it if you are racking the M6

Also along the lines of Classic 400 discussion, what tubes have you rolled through the pre amp? At five 12AX7's and one 12AT7, thats a lot of glass to play with. What has given you the best results? On that same line of questioning, have you contemplated running KT88's?

 

[Kaa]

Sell me a Max bass preamp and foot switch... You wont need it if you are racking the M6

Also along the lines of Classic 400 discussion, what tubes have you rolled through the pre amp? At five 12AX7's and one 12AT7, thats a lot of glass to play with. What has given you the best results? On that same line of questioning, have you contemplated running KT88's?

Would it be possible for one of the amp makers to do a low powered version of the CL400? Copy the circuit and just drop the wattage? I don't know about such things, or if it's even worth the effort. Just adding my 2 cents.

 

[CL400Peavey]

Would it be possible for one of the amp makers to do a low powered version of the CL400? Copy the circuit and just drop the wattage? I don't know about such things, or if it's even worth the effort. Just adding my 2 cents.

Possible? Probably.
Likely any amp company tries it? Very low.

Peavey doesnt even make an amp that runs on 6550's anymore. Fender does, and ampeg does as well... But those are still 300 watt amps.

I would like to see a 50/100 watt switchable amp using two 6550's/KT88's.

 

[groovaholic]

Sell me a Max bass preamp and foot switch... You wont need it if you are racking the M6

Also along the lines of Classic 400 discussion, what tubes have you rolled through the pre amp? At five 12AX7's and one 12AT7, thats a lot of glass to play with. What has given you the best results? On that same line of questioning, have you contemplated running KT88's?

In the Classic 400:
V1; I like the tone of JJ 12AX7s to knock down the highs a bit, but I get better headroom and clarity with an NOS 5751

V2 just always sounds best to me with a Sovtek 12AX7LPS.

V3-V5 I have the reissued Tung-Sol tubes, clear and no microphonics. I don't notice a ton of tonal difference swapping these around, but I do notice more or less background noise.

In V6 I paid the extra money and got a balanced and gain-matched tube so that the 2 sides of the phase inverter would be symmetrical.

For power tubes, I've not only considered KT88s, I've installed a set! I'm running an octet of JJ KT88s based on PM conversations with Bobby Baldwin; he said that the original "6550" tubes in the Classic 400 were odd Chinese tubes that aren't true 6550s, their impedance was different and so the Classic's output transformer had to be made to match their impedance.

He felt that the JJ KT88s were the best match available and the best chance for the amp to put out rated power.

After I biased my Classic 400; I ran a 40 Hz sine wave into the front end and monitored the output on an oscilloscope. It put out over 40 volts into a 4-ohm load, and was still a clean and smooth waveform. Given that P=V^2/R, that means P=1600/4, which gives over 400 watts.

And you'll notice that I tested it at 40 Hz...this amp delivers it's power down at the fundamental.

Anyhow, I'd sell you one of my Max preamps, but they've all sold already. But I do have the footswitch (which also toggles/combines channels on the Classic) and I'm not really using it. PM me if you're interested in it...

In the Max, the JJ 12AX7 gave me the best reduction in highs, but bear in mind that I was using my Dingwall and it's a REALLY bright and airy bass.

YMMV and tube-rolling is always well-worth the effort.

 

[CL400Peavey]

So KT88's it shall be. Thanks for the run down.

What were you using as a 4 Ohm dummy load?

 

[Ender_rpm]

On the subject of smooth transition- my EBS classic t90 is the bomb. It's only 90 watts, but damn. Do a search for my NAD thread, I have some good clips In there. A little pricey but worth it.

 

[jpknox]

interested in hearing your review of the alphabass - ive got one and love it - but it doesnt really provide much volume beyond a small club gig

 

[NWB]

My Aggy TH500 does exactly what you described. It really is a fantastic little head. Fat, warm and tubey but can still manage a to get slightly overdriven when pushed.

Agreed. Although you can also go more than slightly overdriven if you want to. It can go full chainsaw if you dime the gain and drive.

 

[groovaholic]

interested in hearing your review of the alphabass - ive got one and love it - but it doesnt really provide much volume beyond a small club gig

I really liked the clarity of the AlphaBass, but felt like it could have used a lot more "grunt".

It was a clean take on "tube tone" vs. the grit and fur that most of us expect.

Now, I wonder if swapping in a 12AX7A in place of the 12AT7 phase inverter would goose that power amp section harder.

Also, maybe put a REALLY high gain 12AX7A in V1 to get some drive up front...although I've discovered that I really don't care for preamp tube distortion.

Then set the bias right up at 70% and maybe put a set of new tubes in there...

With 160 watts, the Alpha really needs an efficient speaker or speakers to put out gigging volume. When I first demo'ed mine, I used my Genz Benz GC610XB and it was plenty loud.

At home, I had a 15+horn cab that sounded nice but was REALLY inefficient.

Bottom line: if I walked into Music Go Round and saw an AlphaBass for a decent price, it would probably go home with me. I like the Peavey sound and I think their USA-built gear has EARNED it's reputation for reliability.