input pad switch question

[fatty]

well i finally got my valve mic pre built and running. just giving it a quick test on voice and acoustic guitar and everything seems ok. but when i stuck it in front of a guitar amp the pre distorts pretty severely. now what i think i need to do is build a pad onto the front of it. i've got a schem for a h pad (a balanced pad, before the input transformer) with a table of resistor values for 5,10,15,20 db pads. i haven't decided on the value yet, but when i do decide, i want it to be on a switch. what sort of switch do i buy and how do i wire it? spdt dpdt etc etc..?

thanks.

[Kev]

I like the pad on the front of this one.
A simple dpdt switch mounted on the front panel.
you can vary the resistors to get your desired attenuation.
do a search for H pads and you should find a chart or two

http://www.jlmaudio.com/JLM99XMB.pdf
short form
http://www.jlmaudio.com/Simplest%209...%20Circuit.pdf

in fact now that you have a tube based pre ...
go for a gain block pre ... with or with-out the servo and here is many choices of transformers and gain blocks.

[fatty]

hey kev,

very helpful as usual! thanks.
yes, i was planning on the jlm as my next project. i've emailed jo a couple of times about pricing and availability, but he hasn't replied.

maybe you could hook me up. , but i'm getting ahead of myself. i really need to focus on completing and racking this valve pre first!

[fatty]

yikes, joe has updated that his 99v kit page again, with photos of the kit. looks like he's almost ready to ship. it looks really sweet!

http://www.jlmaudio.com/JLM99V.htm

[Kev]

Originally posted by fatty
... maybe you could hook me up. , but i'm getting ahead of myself. i really need to focus on completing and racking this valve pre first!

yep
be patient and in a couple of weeks all the details will be there and I'm sure pricing and shipping details as well.

I spoke to Joe today and I think he may be as excited as I am with this project.