Amps w built-in attenuators?

[arcadesonfire]

I've gotta strip down my setup to a single, more portable amp, and my favorite sound is the slightly power-tube overdriven plexi-like EL34 sound--largely because it responds so well to pedals IMHO. That always requires lots of volume, so I've been using a Hot Plate for years. Its too much to carry head, cab, and attenuator around NYC now though. ...

 

 

 

So what amps offer a built-in attenuator? Does THD have any competition?

 

 

 

Also, it's really hard to deal w the stepped volume of my hot plate. I always want to be somewhere between the notches... Different venues need different volumes! Are the attenuators in the univalve and bivalve stepped like that?

 

 

 

thanks!

[WRGKMC]

There are some amps out there that have variable wattage settings. How that's done varies. Some may use 4 tubes and allow you to take two of them off line to cut the wattage in half. Other amps cut the tubes plate voltage. I have a couple of tube amps, a Sound City and a Music Man head that do it that way. No amps to my knowledge have a hot plate circuit built in. The main problem with that kind of circuitry is a hot plate has large ceramic resistors that develop allot of heat that needs to be dissipated. Some even use a light bulb to act as an induction shock absorber and all that takes up space. I think the best you may be able to do is get a variable wattage head. I haven't seen many that use a plexi circuit however.

 

Marshall has one that takes a set of tubes off line and cuts the wattage in half. http://www.americanmusical.com/Item--i-MAR-DSL100H?src=Y0802G00SRCHCAPN&gclid=CMHAw-CxlsUCFdSTfgod_TQAYQ You can actually do that mod with most any 100W head or just pull one set of tubes and run one pair at half wattage.

 

 

Mesa has one with three wattage settings http://www.sweetwater.com/store/detail/Mark5HDBLU?adpos=1o5&creative=55281441361&device=c&matchtype=&network=g&gclid=CMeot8mvlsUCFU6UfgodpKgAqg

 

Bogner does a similar thing http://www.sweetwater.com/store/detail/EcstasyHD20th/?utm_source=Google&utm_medium=PPC&utm_campaign=guitars&utm_term=bogner_ecstasy&adpos=1t1&creative=66263650081&device=c&network=g&matchtype=b&gclid=CPGJlouxlsUCFUJrfgodUBYAow

 

Most of the others are low wattage heads between 20 and 5W that may have 3 wattage settings.

 

Don't know if this is an option. Using different speakers with different SPL ratings is just as effective as using a hot plate. A high SPL speaker is obviously going to be more efficient then a low SPL speaker. The difference between a high and low efficiency speaker can be dramatic. A typical 100db speaker can be twice as loud as a 90db speaker and an 80db speaker can be half as much as an 90db. Don't know what you're using for a cab, but have a two speaker cab where you could switch which speaker you're using and having a head with variable wattage might give you more actual volume levels. Of course having two different speakers will have two different frequency curves as well so you'd need to find one that has simual response curves at a lower SPL level.

[Phil O'Keefe]

I've gotta strip down my setup to a single, more portable amp, and my favorite sound is the slightly power-tube overdriven plexi-like EL34 sound--largely because it responds so well to pedals IMHO. That always requires lots of volume, so I've been using a Hot Plate for years. Its too much to carry head, cab, and attenuator around NYC now though. ...

 

So what amps offer a built-in attenuator? Does THD have any competition?

 

Depends on how much you want to attenuate. There are a lot of amps out there with variable output power settings (7.5 / 15W, etc.), although not a lot with the same type of full-featured attenuators you'll find in the THD amps.

 

Also, it's really hard to deal w the stepped volume of my hot plate. I always want to be somewhere between the notches... Different venues need different volumes! Are the attenuators in the univalve and bivalve stepped like that?

 

thanks!

 

I am a Univalve owner, and I even went so far as to walk into the other room to double-check for you - the attenuator knob is a fully adjustable rotary control. It's controlling a large rheostat, so it feels grittier than a standard volume pot, but it's fully adjustable, and not a stepped rotary knob or rotary switch.

 

A couple of other thoughts... be aware that the Univalve, while very cool, is still fairly heavy. Part of that is due to its heavy-duty and rugged construction.

 

I find it does best in a band situation when you run a 6550 tube in it, which IIRC gives an output of about 11-12 watts. Cleans go bye bye with a 6L6GC or a EL34 if you try to push it loud enough to hang with a band. Also, your speaker enclosure and efficiency will be important - you'll need a very efficient speaker to hang with a band with a Univalve.

 

While I like the Univalve a great deal (it's a great recording tool IMO), the EQ on it leaves a bit to be desired. I'd recommend an EQ pedal of some sort for use with it for more flexibility.

[onelife]

There are some amps out there that have variable wattage settings. How that's done varies. Some may use 4 tubes and allow you to take two of them off line to cut the wattage in half. Other amps cut the tubes plate voltage. I have a couple of tube amps, a Sound City and a Music Man head that do it that way. No amps to my knowledge have a hot plate circuit built in. The main problem with that kind of circuitry is a hot plate has large ceramic resistors that develop allot of heat that needs to be dissipated. Some even use a light bulb to act as an induction shock absorber and all that takes up space. I think the best you may be able to do is get a variable wattage head. I haven't seen many that use a plexi circuit however.

. . .

 

 

I have a Mesa Boogie Subway Blues with a Half-Power speaker jack in the back. It engages a power resistor in the output circuit - albeit only a 20 Watt amplifier.

 

 

[Midlife Rocker]

I've got a THD Bivalve 30. It's a great amp. Built-in hot plate for at home use. I never use the hot plate at a gig. I've run several different combination of tubes...EL34, 6L6, 6550...etc. For me I settled on 2 KT88's. This is one of the big advantages of the THD, "Self Bias". Tubes can be just about any combo and you can swap them out to find the tone/sound you like without having to bias them. I even use oven mitts to swap them on the fly

 

As Phil mentioned...it's heavy. BUT...not as heavy as my "Evil Twin" head that feels like 150lbs. Here's both my work horses to give you perspective on the size.

 

 

 

 

 

 

 

 

[Phil O'Keefe]

 

 

I have a Mesa Boogie Subway Blues with a Half-Power speaker jack in the back. It engages a power resistor in the output circuit - albeit only a 20 Watt amplifier.

 

 

Even if your amp doesn't have one like onelife's does, it's pretty easy to put together a DIY speaker load box for a small low-wattage amp.

 

Eight ohm, twenty watt ceramic resistors are pretty inexpensive - about a dollar each at Radio Shack. The 25W version is just a little more, but even if you opt for the higher watt resistor, do read the reviews for the 20W version - they're pretty hilarious!

 

[WRGKMC]

You can get away with doing that on a low wattage amp but I believe he was talking about a Plexi Marshall either 50 or 100w. The heat dissipation on a cranked Marshall can melt wires inside a head. The transformers are also finicky. I don't even advise running a hot plate on one because the output transformers aren't heavy duty like other amps. One good power surge and they're toast.

 

The magic of a tube amp is not "preamp tubes". It's not "all the components". It's not "power tubes". The magic is centered mainly on one factor: the interlocked dynamics of saturating power tubes directly interacting with a distorting/compressing guitar speaker. The speaker does *not* act merely as a static R/L load. It is more dynamic.

 

http://www.amptone.com/powerattenuatorfaq.htm

[DeepEnd]

It is not true that the amplifier can work as the attenuators. Transistor can only effect your sound and noise quality. Attenuators have different purpose than the Amplifiers. There are some amps out there that have variable wattage settings. How that's done varies. Some may use 4 tubes and allow you to take two of them off line to cut the wattage in half. Other amps cut the tubes plate voltage.

First, welcome to the forum. Second, this is a moderately old thread. I'm reasonably sure the OP has found a solution by now. Third, nobody is talking about amps being attenuators. The question was whether there exist amps that have attenuators built in, and that question has been answered.

[peteyforto]

Tone King