Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: jackplug1 on February 06, 2022, 01:01:29 pm

Title: Power brake attenuator question
Post by: jackplug1 on February 06, 2022, 01:01:29 pm
Has anybody built this:

https://blueguitar.net/new/schem/misc_mod/volreduc.gif (https://blueguitar.net/new/schem/misc_mod/volreduc.gif)

If so is any good or are there better designs out there now?
What sort of choke/inductor is that, is it and air core type or does it have an iron core,
the wattage rating seems excessive at 150watt
Title: Re: Power brake attenuator question
Post by: CO_Hoya on February 06, 2022, 02:08:44 pm
I built a version of the Hewitt (JohnH) attenuator recently, kind of a fun project.

Simple Attenuators - Design And Testing (https://www.marshallforum.com/threads/simple-attenuators-design-and-testing.98285/) (Marshall Forum)

The thread linked above is a long one and it can be hard to glean info, but the circuit designer and a couple of others there have been good about answering questions, etc.
Title: Re: Power brake attenuator question
Post by: PRR on February 06, 2022, 07:46:46 pm
...What sort of choke/inductor is that, is it and air core type or does it have an iron core, the wattage rating seems excessive at 150watt...

Get it from a Loudspeaker Crossover Parts catalog. PartsExpress is suitable in North America.
Title: Re: Power brake attenuator question
Post by: acheld on February 06, 2022, 09:36:39 pm
Try this:

https://www.marshallforum.com/threads/simple-attenuators-design-and-testing.98285/

Well tested, works nicely.
Title: Re: Power brake attenuator question
Post by: Joel on February 07, 2022, 04:50:04 am
I built two of JohnH's M2's last year.  I'm still very happy with them.
Title: Re: Power brake attenuator question
Post by: jackplug1 on February 08, 2022, 11:40:15 am
The simple attenuator article is quiet interesting.
Would the line out on the schematic in the original post (mission amps) benefit from an isolation transformer?
Title: Re: Power brake attenuator question
Post by: Blueboozer on February 08, 2022, 10:23:09 pm
I built one of these a while back and it works pretty well.


Title: Re: Power brake attenuator question
Post by: jordan86 on February 09, 2022, 07:26:48 am
I built one of these a while back and it works pretty well.

Is this a clone of a Trainwreck/ Dr Z Airbrake?
Title: Re: Power brake attenuator question
Post by: Blueboozer on February 09, 2022, 12:19:00 pm
I believe so. 
Title: Re: Power brake attenuator question
Post by: jackplug1 on February 09, 2022, 12:34:43 pm
I built one of these a while back and it works pretty well.

The resistors a very expensive at £25, maybe you could make them from a ceramic electic fire element