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Any demand for a good high output solid state head ?

#61
2x4strgkramers said:
First stage build a functional amp. Harder then it sounds.
Click to expand...

Indeed.

In your OP, you asked what people want. I answered. If it weighs more than one or two pounds per 100 Watts, then I am not interested. If your understanding of bass amp design is limited to believing that big transformers are vital to tone, then I am not interested.

It sounds like you have decided on a design. If so, go ahead and build it.

My approach would be different. I would start with bench testing of the existing design that you are happy with, to find out what makes it tick. Then I would look for ways to emulate the performance of the lead sled, using lightweight techniques.
 
#62
My everyday hands on experience tell me to build a reliable amplifier requires using components that are capable of disapating lots of heat. Why ?? becuase lots of power generates lots of heat. I know I can save at least 10-15 lbs over the existing design by chaning the materials in the case as well as other items.

I am interested in building burly durable amplifiers that make scads of super clean back end power. The preamp is going to require a bit of a redesign due to obsolete components so I may try to do a hybrid dual input arragnement but it will add lots of weight but for a small 12ax7 tube the power requirements should be easily manageable.

Either way it i an edevor I am interested in getting going on and When I get started I will post up all the details.

I doubt it'll be cheap though becuase small quantitys components never are.

2lbs per 100 wats. Should be doable with a class A&B if case construction and packgaing is optimized. The head currently wieghs 40 lbs and I would bet at least 1/3 of it is the 3/16 thick steel case it is enclosed in. It was built for serious road use.


I plan on trying to refine it but the basic design is good enough that I think most of it is a packaging issue with the weight but the transformer is heavy and as much as I like switching power supplies I doubt I could economically build something that I felt was "Good Enough" even with the best materials avialable but you never know.

fdeck said:
Indeed.

In your OP, you asked what people want. I answered. If it weighs more than one or two pounds per 100 Watts, then I am not interested. If your understanding of bass amp design is limited to believing that big transformers are vital to tone, then I am not interested.
It sounds like you have decided on a design. If so, go ahead and build it.

My approach would be different. I would start with bench testing of the existing design that you are happy with, to find out what makes it tick. Then I would look for ways to emulate the performance of the lead sled, using lightweight techniques.
Click to expand...
 
#63
To get 500 Watts down to 2 pounds per 100 Watts, you have to get it below 10 pounds. I set that limit as a generous one, but it requires switchmode design. My 300-Watt head weighs 2.5 pounds.

You don't want to attempt a DIY switchmode power supply. There are experts who know how to do this, but it is quite a specialized skill and requires test equipment that most of us do not have.

There are a few brave souls who have attempted DIY Class-D power amps, but I get the feeling that they are experienced engineers who are tinkering with audio on the side. Some of their tales are told at the www.diyaudio.com forum. That might be a good place to bounce some of your ideas around. I would venture to say that every Class-D bass head design presently on the market is the culmination of a steep and expensive learning curve. This is why even some of the greats are prudent to use OEM power amp modules.

A common story on diyaudio is the "my first design, I just blew out all of the MOSFETs."
 
#64
I absolutely dislike Class D amplifiers "way to much distorition". I am thinking however about some non traditional methods to acheive the needed voltage for good operation.

That being siad there are ways to make AB's more efficient. I would love to build a monster A but it would wiegh 150lbs by the time we got to 300watts.

Do I think I can hit 10 lbs at 500 watts ?No Do i think I can do it a 22-25 yeah. Thats not really heavy. Also the problem is the Class AB vs D. I like some of the benefits of the H and as for switching power supplys. Well there enough data out there to make something work. I think I may stick with my old fashioned transformer. What I was thihnking about doing though was rectiying with a tube. There a new spin on a old idea. It isn;t the transistors that pose the issue for warmth it is the transformer.

I wonder how many guys have class D amps and love them becuase the THD is high enough that they start feeling warm?

fdeck said:
To get 500 Watts down to 2 pounds per 100 Watts, you have to get it below 10 pounds. I set that limit as a generous one, but it requires switchmode design. My 300-Watt head weighs 2.5 pounds.

You don't want to attempt a DIY switchmode power supply. There are experts who know how to do this, but it is quite a specialized skill and requires test equipment that most of us do not have.

There are a few brave souls who have attempted DIY Class-D power amps, but I get the feeling that they are experienced engineers who are tinkering with audio on the side. Some of their tales are told at the www.diyaudio.com forum. That might be a good place to bounce some of your ideas around. I would venture to say that every Class-D bass head design presently on the market is the culmination of a steep and expensive learning curve. This is why even some of the greats are prudent to use OEM power amp modules.

A common story on diyaudio is the "my first design, I just blew out all of the MOSFETs."
Click to expand...
 
#66
Rectifying with a tube? I thought this post was about solid state power amplifiers? The last 50V rectifier tube I saw was in a 1920's battery charger and stood a foot tall. This conversation has banged off every wall, covered every angle and makes less sense with every post... Yeah Crown's new Class I digital amplifiers with .35% THD 20-20K at 8,000watts out are full of distortion. I have hum in a preamp that needs found, see you guys... BOB OUT
 
#70
Must be a bunch of people around hear with no low detail hearing left. I hear very minimal amounts of distortion with good speakers.

Yes you can rectify with tubes. In fact you have to rectify the AC voltage to DC at some point. There are many ways to achieve goals.

rbonner said:
Rectifying with a tube? I thought this post was about solid state power amplifiers? The last 50V rectifier tube I saw was in a 1920's battery charger and stood a foot tall. This conversation has banged off every wall, covered every angle and makes less sense with every post... Yeah Crown's new Class I digital amplifiers with .35% THD 20-20K at 8,000watts out are full of distortion. I have hum in a preamp that needs found, see you guys... BOB OUT
Click to expand...
 
#71
I have to address a little comment made back on page 2, I think. Gk heads work great with Ampeg cabs. I used an Ampeg 4x8 with a GK 1001RB, and never lacked for lows or headroom. I now use a Bergantino 212 with a GK 1001RB-II, and have never even thought of using the biamp feature. It's just not that relevant in today's market, IMO. I do see what you are saying about power loss in a passive crossover, but if it were THAT marketable to do away with it and go with a post preamp crossover, you would see it done a lot more than it already is. That right there might tell you what kind of market share is looking for such a device.

If you do run to the realm of switching power supplies, I would recommend going with a prefab power supply that is of the proper current ability that your power section would need. I have done marginal study on power supplies, and I could easily build a tranformer/bridge rectifier/capacitor filtered power supply, but that's about it. IF you are looking into tube rectification in a power supply, you may have to go with a very large tube as compared to regular rectifier tubes as used for guitar amplifiers. Also, a tube rectifier of a "normal" size would have too much voltage sag at the ends of it's power limits to make your amplifier as clean sounding as you seem to want.

I also have to have you check this thing out: http://www.chambonino.com/construct/const9.html

That is a full 1,000 watt tube amplifier, and you must notice how large and bulky it is. Without moving to some new and different kind of power supply, you aren't going to be able to get the weight down that much. Toroidal transformers may help, but not that much.
 
#72
2x4strgkramers said:
Must be a bunch of people around hear with no low detail hearing left. I hear very minimal amounts of distortion with good speakers.
Click to expand...

122426_f520.jpg
 
#73
2x4strgkramers said:
Must be a bunch of people around hear with no low detail hearing left. I hear very minimal amounts of distortion with good speakers.
Click to expand...

If I can't hear it, and the audience can't hear it... if a tree falls in the forest... :D

If it's audible, then it's measurable. If it's measurable, then it can be modeled.

Yes you can rectify with tubes. In fact you have to rectify the AC voltage to DC at some point. There are many ways to achieve goals.
Click to expand...

Look up the current ratings for typical rectifier tubes.
 
#78
So you want a light-weight solid state amplifier using heavy transformers or giant vacuum tubes producing 1,600W into 2 ohms, bi-amped for crossover into modern speaker cabs.

I'm just confused about what happened here. If you want to make a modernized copy of that head because you like it, then cool! It sounds like a fun project, and I wish you luck and satisfaction with it.

I think everyone's just saying that it's probably over-optemistic to think that there's much of a market for that product. Cost versus benefit, y'know?

I'd still be interested to hear it, though. If you ever get a chance to make a good recording of it, send me a PM.
 
#80
2x4strgkramers said:
Must be a bunch of people around hear with no low detail hearing left. I hear very minimal amounts of distortion with good speakers.

Yes you can rectify with tubes. In fact you have to rectify the AC voltage to DC at some point. There are many ways to achieve goals.
Click to expand...

I will agree I for one have compromised hearing and I hate it. It got that way, however by standing on stages with other players too loud amplifiers for way over forty years. I surely don't have the "golden ears" you seem to have.

Yes you can use a single tube rectifier - up to a power of about 50W with commercially available tubes. There is no rectifier tube on the market that will handle the needs of a 1600W SS amp. The only way you CAN use a tube is to merely feed the tube section. What effect that will have on sonics is a crapshoot at best!

As this thread continues, and I am enjoying it, it seems, more and more, that there is little actual solid logic coming from you. You say that you work in electronics. In that case you should have a better understanding of what is possible within the various branches of that field.

As another quick question: do you not have a spell checker on your computer? If you do, why not use it? Some of your posts have been barely understandable.

Paul
 

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