Home made Attenuator questions

[Regis]

I found this page on Ted Webers site explaining how to make a DIY attenuator and thought it would be ok to build one for my Kay 720 for late nite jamming. The Kay is about 20-25 watts and to build a small attenuator like Ted sez didn't seem too hard.

I started looking around for parts and while I was at the Parts Express site I saw this L-Pad. What do you think about using that as a poor mans attenuator for this amp rather than using Teds idea?

I've seen websites where guys have used Lpads like this in small amps but wanted to get reassurance from some of you guys.

[Enzo]

Yes, you could use that. Ted's idea was just two resistors though, simple enough.

[hasserl]

Yeah, the L-Pad will work for that small amp. I would not be comfortable using one alone in a higher powered amp, as they do build a lot of heat and if it fails in operation the results could be pretty bad for the amp.

[Regis]

Enzo, Hasserl, thanks guys. For ten bucks I'll give it a try. I still will buy the parts for teds circuit, I am making it complicated because I want to make it switchable between -3db, -6db, and none at all, plus installing it in the amp somehow. It seemed the Parts Express Lpad would achieve the same thing with more simplicity.

thanks again.

[Regis]

By the way, Enzo, I never told you I am an old Michigan man myself. I grew up south of you in Jackson. I've been in Atlanta since 1983. Lately the old home town is looking mighty attractive, for various reasons. I spent a lot of time in Lansing when I was a young man. I had a girl that went to MSU.

do you have a shop, or do you just have a lab at your house? Maybe sometime when I come for a visit I could stop by. When I visit my buddies up there we usually stagger out of a bar or two in Lansing.

regis

[Enzo]

I am in the shop on Lansing's south side monday through friday after 6:30PM:

Shiawassee Technical Services
5223 South ML King
Lansing, MI 48911
517-882-2544

ANyone in the area is welcome to stop by. My shop is tiny, but it is in a store, not my rural home. Home is 20 miles away. Oh, and other than a lunch hour at some point, I am here until dawn.

That is one block south of Jolly Rd, next door to the Metro Bowl. A block and a half from Deja Vu.

I used to be right across the street from Elderly Instruments, but my building was sold and I had to move away. That hurt business I'll say. But I still do a lot of work for them. They just can't trot across the street with the item in hand any longer.

Enjoy the bars, we got plenty, but don't show up drunk, thanks.

Oh, and 3db is a very small change in volume. 6db is the difference between the hot and cool inputs on the basic Fender input.

[Rob Mercure]

Hey Regis,

I've not attempted to search the old Ampage archives but I believe they're still up (?). Several years ago - before 2000 if I remember - there was a long discussion on making a speaker emulator with reactive components that more closely resembles a true speaker load than simple resistors do. Perhaps you can find it. While I want to credit R.G. it may have been someone else such as Randy Akien who provided a fairly easy to build circuit. You might check out these guys websites if the archives don't score - or perhaps do a google on "home made speaker simulator" or such (you may have to tweak the search to get rid of the commercial units). Or you could do a patent search on a commercial unit.

Fer myself I've built a lot of little amps from a couple of watts on up to my stage set up so I can usually find a volume that suites. You might also look around for a truly inefficient speaker - somewhere I saw something advertised that was about 70 dB/Watt and couple it with lower power output tubes - just depends on what your "hassle index" is.

Rob

[Regis]

Hi Rob,

I may look for that, thanks. I just wanted something for this Kay because at about 20 watts it's not a real ball buster, but a little loud for jamming along with a hifi. I just wanted to be able to dial it down a little for that and also if I go to a jam in a bar and it's a little too much I can cut it down and still get good overdrive, which it does well. I sort of wanted to install the attenuator inside the amp too, for convenience sake, not sure about that yet.

I put an Eminence "Big Ben" in it and really love it, so I won't be changing speakers.

This is a really cool amp, I'll post some pics when I get done redoing the back panel and get the attenuator figured out.

Say, Ted Weber mentions on that home made attenuator page about adding caps to give back some high end, anybody have an idea of what range of values to use?

[Alf]

reactive load

Regis,

Here is a site where you can find info on reactive loads.
This might help .
http://www.geocities.com/SunsetStrip...ker.html#howto
I do have some old info from 1998 from Ampage. If you want it let me know.

Regards , Alf

[Alf]

I was too fast with my answer Regis, I remembered Adam Alpern's very informative site, here 's the link . http://amps.zugster.net/articles/attenuation
And there's Bruce Collins' volume reducer on Blue Guitar.

Alf

[Rob Mercure]

Hey Alf - thanks for the good "memory" - it was the Randy Aiken one that I was thinking. Since you remember the discussion weren't there a couple of folks who built one and sent back good reports? At least that's what my "selective memory" states (hmmm, now what did I have for dinner last night?).

Rob

[Alf]

good memory

Hi Rob,

No my memory doesn't serve me that well but I keep lots of Ampage threads in a kind of database for reference.
There weren't any answers of people actually having built Randall Aiken's design . But if you would like to have a look at the info I can send you the zipped files.
Just let me know.

Regards , Alf

[Analog Assassin]

Hi Rob,

I may look for that, thanks. I just wanted something for this Kay because at about 20 watts it's not a real ball buster, but a little loud for jamming along with a hifi. I just wanted to be able to dial it down a little for that and also if I go to a jam in a bar and it's a little too much I can cut it down and still get good overdrive, which it does well. I sort of wanted to install the attenuator inside the amp too, for convenience sake, not sure about that yet.

I put an Eminence "Big Ben" in it and really love it, so I won't be changing speakers.

This is a really cool amp, I'll post some pics when I get done redoing the back panel and get the attenuator figured out.

Say, Ted Weber mentions on that home made attenuator page about adding caps to give back some high end, anybody have an idea of what range of values to use?

Weber's miniMASS attenuator uses a 2uf bipolar cap, I upped it to a 10uf because I thought it was too dark at higher attenuation levels.

[Regis]

Weber's miniMASS attenuator uses a 2uf bipolar cap, I upped it to a 10uf because I thought it was too dark at higher attenuation levels.

Thanks Aa, I'll give that a try.

[Regis]

Update, where to put the bypass cap?

Sorry, dumb question, where do I put the bypass cap for this L-pad?

Here is the schematic.

This is the L-Pad.

I put it between pins 2 and 3 and it seemed to work ok, just wanted to confirm it properly with you guys.

I hooked it up and it sounds pretty good. I ran my Bandmaster with it and it works ok. It gets pretty warm, I have a couple of ideas about that I will pass along when I get it finished. I have a funny idea about the enclosure that will look cool.