Step up transformer recommendation

[timp]

As an altec lover, I want to add a step up transformer to match mc cart to operate with mm phono stage. Would you give me some recommendations of what altec transformers I should use? Thank you.

[donaldpatten]

Timp
Phono preamps have built in RIAA equalization that boosts the lows and rolls off the highs.
If you connect a mic to a phono input it will sound muddy and muffled . If you can change the preamp circuit to a flat freq resp... then you could use it.
Don

[martyh45]

There are a few factors to consider when picking a transformer, cartridge output impedance, output level and phono preamp gain. Input transformers can work well in certain situations but not all of them. If you are looking for something with Altec heritage that is flexible enough to use in many different situations, try Cinemag transformers. The owner designed transformers for Altec back in the day and his MC step ups are supposed to be really good.

[edfallon]

Originally posted by timp:
As an altec lover, I want to add a step up transformer to match mc cart to operate with mm phono stage. Would you give me some recommendations of what altec transformers I should use? Thank you.

<font size="2" face="Verdana, Helvetica, sans-serif">If you'd like to keep it Altec you're in luck. An Altec 4722 mic step up xfmr works as one of the finest MC phono SUT's you can buy. The Cinemag is good too and very inexpensive but not quite as good as the 4722.

[bfish]

Uhmmm...(bites tounge, bangs head...)

never mind...

[donaldpatten]

Timp
I misread your post.
The phono inputs for Moving Magnet carts are 47k Ohms to match the fixed coils. A Moving Coil is much lower output and requires a set of transformers.
Check with the cartridge manufacturer for a suitable step up transformer to match the MC to an RIAA 47k phono preamp.
Don

[armandh]

transformers will introduce distortion from the hysteresis cross over I'd put an op amp in there to get the gain also resulting in reducing the mechanical load [wear] at the record.

if you are looking for all tube perhaps a cathode driven grounded grid circuit for loZ input.

[zelgall]

An Altec 15095 is a popular step up transformer for MC's. They have an octal base and a 150 ohm input impedance which works well with a variety of carts.

[timp]

Hi guys

Thanks for the reply. I took a biggest challenge in my short DIY career to build my own linestage and phono stage since I last reported my hum problems. They are far from over. With my busy work schedule, the projects have been slow coming. The phonostage is all tube design (1 12ax7+ 1 6dj8) mm stage. And I thought adding another mc stage would be away over my head. Thus, I decided to go with a transformer. So, I posted this to welcome your wise counsel.

Uhmmm...(bites tounge, bangs head...)

Well, I have been biting my own tongues, too, for it's been painful burning my fingers with soldier and cutting my hands. It's a total frustration yet fun! I know I will be baning my head many times over in frustration.

Looking for a transformer began!

Thanks everyone.

Tim

[gamalot]

I am no electronic wiz and don't know an answer here.
I do know there is a guy on ebay, think he is captain Bob or something and he makes and sells some very nice looking step ups with Altec plug in transformers. The ones he makes with the 4722 trannies go for some pretty steep bucks.

I bought a Luxman PD 121 turn table a while back with a denon MC cartridges. The guy threw in a denon step up AU 320 that has dual in and outputs for two TTs. It seems to work just fine and I don't notice any hum when I use that turn table and step up. If I try to use that TT without the step up I would need the volume cranked way past my comfort zone.

Another option you might consider is buying a pre amp that already has MC cartridge inputs. I've had a couple from both Luxman and one from Yamaha, I think a CX 1000 and no external step up was needed.

Gary