[Niteshade]

Thank you for your comment! 


SEP designs are one of my favorite. They really stand out in the audio world in terms of performance and uniqueness.

Single Ended + High Power = SEP

[Niteshade]

Wow- I cannot believe there haven't been any questions about SEP amplification. It's the best thing since sliced bread, the bee's knees! 

I know there are not too many (if any) available elsewhere, so I'm happy to answer any questions you have about this delightful amp configuration.


Blair

[jtwrace]

What is your highest powered amp that can drive electrostats?

[Niteshade]

You chose a good location to ask that. Would 200 watts per channel be enough or would you like more? The design you're interested in is called a push-pull-parallel tube configuration.

For 200 watts a side, there would be six 6550's per channel.  This would be a **thrilling** amplifier to build and use. I would make it so the tubes would not be pushed hard to increase their lifespan. At the same time this design would increase performance. Overbuilding is the way to go with large amplifiers and saves a considerable amount of money down the road.

Blair

[jtwrace]

You chose a good location to ask that. Would 200 watts per channel be enough or would you like more? The design you're interested in is called a push-pull-parallel tube configuration.

For 200 watts a side, there would be six 6550's per channel.  This would be a **thrilling** amplifier to build and use. I would make it so the tubes would not be pushed hard to increase their lifespan. At the same time this design would increase performance. Overbuilding is the way to go with large amplifiers and saves a considerable amount of money down the road.

Blair

I currently use 300wpc Class A SS amps.  What do you think?  Dips to 2 ohm.  86dB @ 2.83V / 1M  /  4 Ohm rating

[Niteshade]

Two hundred watts should be plenty. I would want to have a special output transformer wound with a 3 ohm tap. With that, I am positive there would not be any load issues.  Variable negative feedback can be used to compensate for what the transformer will not do on its own.

There is a review on my web site relating to one of my 50 watt amps driving electrostatic speakers.

Blair

[jtwrace]

Cost for that amp?

[Niteshade]

The price of that amp is dependent on a few variables, the largest being how much the special output transformers are. I can start providing more details to you via Email. If you would like to, please email me so that I have a reply address.

I can promise that the price will be very competitive.

Blair

[jtwrace]

The price of that amp is dependent on a few variables, the largest being how much the special output transformers are. I can start providing more details to you via Email. If you would like to, please email me so that I have a reply address.

I can promise that the price will be very competitive.

Blair

email sent

[Niteshade]

Parallel tube configurations:

As you can see, there are a great number of uses for parallel power tubes. Push pull parallel designs are indeed common since they work so well.

Single Ended Parallel enjoys the same virtues as push pull parallel. If you have never heard a SEP based amplifier, you're in for a BIG surprise!  Any power tube can be used in SEP configuration and we know how to build around them all. Yes, 300B's & 2A3's can be placed in SEP configuration. In fact, they would perform much,much better that way due to a higher input gain factor. SEP circuits can provide much better depth and sound staging abilities than their lower powered SE & SET counterparts.

Questions are welcome!

Blair

[Niteshade]

Single Ended Parallel, otherwise known as SEP is something worth looking into.

It's unique, not over priced and capable of thrilling those who like either SET or basic push-pull configurations. 

[Niteshade]

It is possible to have both accuracy and high power at the same time. We know how to do it and do it well. A portion of my electronics background involves working with tube HF amplifiers that operate above 1KW. That's some serious power.

The same principles for RF can be applied to AF amplification. One of the biggest rules is no skimping.

Good designs bear good sound. Nothing we do is from 'cookie cutter' stock.  Each model has its own customized circuit made perfectly for the job.

I am always happy to answer questions. Do you have any suggestions?

I'd like to hear form you!

BTW: Thanks to all responsible for getting the site back on it's feet AND for the interim patch job. 

Blair

[Niteshade]

Paralleling output tubes is the ideal way to get high power. Never have I made an amplifier with a parallel output configuration that did not sound better than a single tube configuration, such as basic single ended or push pull.

There is indeed something very special about it: Added power provides superior transient and sustained note response. On top of this, the drive stage for parallel tubes is better made than for single tube setups.  Power plus purity is the result. Output noise is reduced considerably as well.

Even if you are a low power or single ended fan, I sincerely believe parallel output tube configurations are something worth looking into. It's a whole other world of quality sound that can far exceed traditional amplification methods.

NOTE: Our 100 watt monoblocks start at under $3,000 and that includes delivery to the lower 48!
Tube amp trade-ins are worth up to 25% of the sale price!

[Niteshade]

You know something- if Scotty would have used parallel warp cores in the Enterprise, they could have wiped the floor with those Klingons back in the 60's.

Double the tubes, double the performance.  Don't let low power spoil your fun.

[Niteshade]

I have to tell you something-  Tube technology has so much to offer that it boggles the mind!

It has occurred to me that many of you have listened to me prise everything from low power, single ended amp to exceptionally high power models. I have tons of features and upgrades to offer on top of that.

There is a reason for this- everything I build, I enjoy immensely. It is a joy to create whatever I feel like listening to at the moment. 

Niteshade Audio was made to share these creations with the rest of the world. It is my pleasure to design amps and preamps according to what you would like most.

A formula for success includes knowing your listening habits, kind of music listened to, speakers, room size and any other pertinent information. Matching audio equipment to the owner is a sure road to success.

As can be seen, different topologies have special abilities. Parallel output tube configurations can offer substantial power and performance and the ability to easily handle difficult loads.

Some food for thought: El84's can be paralleled. Ever wish for a high power El84 based amplifier? It is indeed possible and they sound incredible. I have a fascinating, specialized circuits  for the El84 and 6V6 that are sure to enchant.

[Niteshade]

Negative feedback refers to an amplifier's circuit that samples the output for volume dips and peaks created by a speaker's impedance curve. Impedance variations away from an amplifier's nominal impedance rating produce either volume deficits or surpluses. (AKA: Stridency, boominess or a perceived 'hole' at specific frequencies.)

As the amplifier samples the output for these dips and peaks, it attempts to compensate for them by cutting or boosting the effected frequencies. The amp wants to flatten the speaker's frequency response. Some people say it the other way around and say feedback flattens the amp's response. Either way you want to view it is fine with me.

Part of an amplifier's signature is how it deals with a speaker's impedance curve. Most of the time, amplifiers have a fixed negative feedback. The term, "It is what it is." comes to mind and that's true. 

I feel it is better to have variable feedback. Variable feedback provides the listener a way to exactly tailor the amp's response to their speaker system. What a difference that makes! It's the same as having a suit tailor made just for you rather than buying off the shelf.  Not all speakers are the same, thus not all require the same amount of feedback. My experience is that less feedback produces better sound. Having the ability to control feedback is of paramount importance for a well-tailored sound system.

What does too much feedback do? It can cause an amp to loose high frequency resolution. It usually slows the amp down, making it sound syrupy and slow. The sound, to me, is more blended and homogeneous. Too much feedback can make some amplifiers sound overly warm because either low or  high frequencies are being attenuated too much. It's typically highs that take the blow.

Sometimes speaker impedance curves are too severe for feedback or even an impedance tap change to improve. When purchasing speakers, make certain the impedance does not deviate too much for the stated impedance. As in, It's not advisable to use speakers that go from 8 ohms to 3 ohms. I would say 8 to 5 would be fine. If the speaker goes down to 4, try the 4 ohm tap on the amplifier.

Closing remarks: Variable Feedback is the ideal way to customize a sound system. This is our approach to insure our amplifiers will match up with most speaker systems perfectly.  It is the ideal solution for those who dislike stridency yet do not want a lethargic or sterile sounding amplifier.

Please call or write for more details. Have you visited our web site lately?

[Niteshade]

Tube amplifiers, by nature, do not require allot of feedback. Making it variable so that the perfect amount is used does make a big difference in sound quality.

[Niteshade]

Questions and Answers:

I will start off with the first questions:

Q: If variable feedback is so good, why isn't it more popular?

A: Most designers believe a set amount of feedback is acceptable. In fact, the feedback is automatically set up fairly high to compensate for worst-case speaker scenarios. Tunable feedback is more expensive to set up since it requires an external control.

Q: My speakers are too bright- will it eliminate stridency?

A: Yes. The circuit is made to eliminate stridency if it is an issue.

Q: My speakers are well balanced. Can it do anything with them?

A: Chances are the feedback control can be set to the minimum. Well balanced speakers do not require as much, if any spectral corrections. Less feedback will make your system sound better.

Your questions are always welcome.