[w8aaz]

So I have a nice Bugle that I built years ago. STill on batteries, I can get all the industrial 9V batteries I want for free, right now.  Set up for standard gain MM app. Got an older MC in a package deal and want to try that. But I don't want to alter the Bugle and want to keep the gain settings for MM option. So I was looking around and found plans for a simple gain stage to boost MC inputs. Mr. Leach designed it. Two transistors per channel, with a 100 ohm input Z. The MC cart is medium output.  About 68 ohms DC resistance in the coils, rated at 1.1mV output. Might almost drive the MM input but I need all the gain I have now to use a MM anyway. Only prob. I see is that there is alot more gain in the Leach pre pre than I will need. Don't want to overdrive the Bugle, as the Pre pre is designed to have enough gain to boost a low output MC. Suppose I will put some sort of atten. on the output to match the gain, either trimmers or ganged pots. A complication but really cheap compared to a set of xfmrs or a commercial head amp.  What you think?   

[analog97]

For a 1.1mv cartridge, it sounds like 12 db gain would do it.  Two suggestions: 1. swap out some resisors in the Bugle to give you the gain you need.  There is a calculator on this site to tell you exactly what resistors you need.  My Bugle is really quiet when I tried about 50 db gain....or 2. (preferred) Build the Piccolo.  It's a tremendous device.

[w8aaz]

Yea I know the gain can be changed on the Bugle, but I would not want to lose the MM gain setting for use with other carts. I suppose that some kind of switching arrangement could be installed to change the gain setting but I am not sure how much complication or awkwardness that would add to the design without further research.  I had considered the simplicity of stepups but then got an idea of the costs involved. Besides, I like to build small projects like this and the cost is comparitively miniscule. Thanks.   

[Sarchi]

I'm going DL103->Lundahl 9206 trafos->Bugle, this setup sounds outstanding; very natural, with a warm, rich midrange presence, pretty good detail and nice extension at both ends.  Hard to know if it would synergize with your cart.  The DL103 only has 0.3mV output.

[w8aaz]

I guess the Lundahl transformers are excellent across the board, but I am not sure what you will be paying for them.  My TT system has been mostly for transcription in the recent past and not extended listening, but if the setup sounds great that might change. The nice thing about the Leach amp is that it is a very simple circuit, using two transistors, supposedly presents a 100 ohm or so load to the cart, and is also supposedly very low noise.  Each amp runs off a single 9 volt battery so no power supply to mess with or wall warts needed, like my Bugle. If it doesn't work well I guess I will have to go to the other options, spend big for an xfmr set for a cartridge I have not heard yet, or mod the Bugle and it will be only MC input then.       

[hagtech]

Just how much gain is in the Leach circuit?  I didn't think it was that much.  And it is real easy to change, set by the output resistor.  In fact, it's not a gain circuit at all in a strict sense, but merely an impedance converter.  Output power is same as input power.  You'll have much more flexibility with a PICCOLO.

jh

[w8aaz]

Well Mr. Leach's head amp claims 26 db of gain, that seems like enough for a low output cart down in the microvolts, but enough to maybe overdrive the Bugle with the 1 MV cartridge. That is why I was thinking gain control. Match the level to more like the MM input or a bit better, the preamp requires more audio gain in the amp than the matching CD player does. Matching output between sources, you know?  Will check out Piccolo. 

[hagtech]

Just lower the value of the output resistor in the Leach.

jh