Hey John Roberts [ sung to the tune of Bo Didley ]

[okgb]

I bought one of these peavey  TMP-1 Tube Preamp cause it was cheap , any comments ? compromises ?

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=200887101748&ssPageName=ADME:B:EOIBSA:CA:3160

 

[JohnRoberts]

You should have asked me first..  8)

That was after my time in product management, because during my time I resisted such products. Never did understand the rationale for "touched by a tube" audio paths. I honestly don't know what's inside that one, but I don't care for the entire category of aspirational "tube"  products.

I do strongly endorse the Peavey/AMR VMP mic preamp and VCL comp/limiter which are serious tube products, while not as cheap. 

JR

PS: I always thought Bo Diddley was a person, is he a song too?

 

[okgb]

fwiw it certainly didn't reviews as good as the AMR 
hopefully worth the parts or usable for such , ebay bordom , bah !
thanks anyway [ the beat and the man are the same ? ]

 

[PRR]

> thought Bo Diddley was a person

Yes, Ellas Otha Bates. But he's also a beat....

One e and ah, two e and ah, three e and ah, four e and ah.

....and a song. "Hey John Roberts" fits the song "Hey! Bo Diddley"

John Roberts done had a farm
(Hey, John Roberts)
On that farm he had some women
(Hey, John Roberts)
....
Hollerin', my baby got towed away
(Hey, John Roberts)
Slipped on from me like a Cadillac-8
(Hey, John Roberts)

{Thread drift} I was jus reading about Cunningham took two Cadillacs to Le Mans in the early 1950s. One stock sedan; the big Caddy OHV engine was not too shamed by european cars, although the hydraulic valves floated right-on-schedule at 4,400RPM which limited its speed on the long straight. He also had a caddy chassis with a semi-streamliner body, but something happened to it. Kinda makes the novel Speed Six not so absurd. {/Thread drift}

 

[okgb]

And John Robert's seems to be a good guy , never heard much about Bo's life
He grew up poor ?

 

[JohnRoberts]

Bo Diddley (RIP) is a MS native so a bit of a legend around here... I am still a Yankee after living here more than 25 years...

If John Roberts had a farm full of women, he wouldn't post so much....  8)

JR

PS: I did have a song written about me by a local band, referring to me "stinking up the lab" when I went through a period of blowing up numerous power amp prototypes at work... My home brew beer has also been mentioned in at least one other song...  but no mentions lately since my house band has moved on.

 

[tchgtr]

  I've been trying to get my hands on one of those VMPs for years, but they appear to be so damn good that the price on them stays quite high on the used market.
  Somebody tried to give me one of the AMR boards, but I stupidly told them they should sell it, and they promptly gave it to someone else. Maybe it was hot. Didn't have enough room for it any way, but it sure sounded nice.
Home brew? No moonshine?

 

[JohnRoberts]

Home brew? No moonshine?

I've sampled moonshine but it doesn't do it for me... Beer is my evening beverage of choice, and home brew is the highest quality beer I can get reasonably. I find that imbibing too much actual alcohol causes me to lose consciousness.  :

I had an uncle (RIP) located in Asheville, NC. who tried to legalize selling shine in small bottles as a novelty tourist industry, but the revenuers didn't approve. I suspect he would have no trouble securing sources up in the hills around Asheville.

Life is too short for inferior beverages... I brew my own beer, and roast my own coffee. I'd grow my own green tea, but doubt the climate is right and don't know how. My theory is that most people tolerate the taste of crap coffee to get the caffeine buzz, and tolerate crap beer to get the alcohol buzz... life is short, embrace quality.

JR

 

[tchgtr]

  Yeah, I used to brew also (emergency earthquake water now stored in carboys), but I just don't drink enough to make it worthwhile. Best beer I ever had was an imperial stout made from scratch by a friend in Jersey, who is lamentably now gone.
  Used to make a strawberry beer that sat on 11 lbs of blended strawberries for 45 days. It wasn't sweet, and it was fun to see people try to figure out what the secret flavor was. I was also partial to wheat beers, which were easy to make.
  Green tea is cheap enough, unless you go down to Chinatown for the real good stuff. 

 

[JohnRoberts]

  Yeah, I used to brew also (emergency earthquake water now stored in carboys), but I just don't drink enough to make it worthwhile. Best beer I ever had was an imperial stout made from scratch by a friend in Jersey, who is lamentably now gone.
  Used to make a strawberry beer that sat on 11 lbs of blended strawberries for 45 days. It wasn't sweet, and it was fun to see people try to figure out what the secret flavor was. I was also partial to wheat beers, which were easy to make.
  Green tea is cheap enough, unless you go down to Chinatown for the real good stuff.

I was never a fan of the wheat beers since I was typically in Germany during cold months, so I stuck to dark alt beers while there. I finally got a chance to sample some light wheat beer in July after a race in Atlanta, and it was very good... with a slice of lemon.  There were some interesting fruit beers made in belgium, since they were also attracted to high alcohol brews. I experimented with brewing high alcohol beers decades ago, but have since settled on more modest fire(water)power. IMO too much alcohol tastes bad (a hot taste)...

If you are drinking beer just to get drunk, thats why they invented shots....

JR

PS: Japanese sencha for good green tea... I also developed a taste for oolong while in HK. (that reminds me I haven't had any oolong for years). 

 

[okgb]

Dark Beer's Best  ............... and there are so many good craft / micro breweries these days

 

[bigugly]

I bought one of these peavey  TMP-1 Tube Preamp cause it was cheap , any comments ? compromises ?

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=200887101748&ssPageName=ADME:B:EOIBSA:CA:3160

a friend and former member here had a cool mod for these. they are actually decent enough pre-amps albeit a little noisy. (at least mine was) I dug up the original thread but the schemo was gone so I dug thru my archives and found it. have fun.

 

[okgb]

Thanks for posting  , what was the mod or thread [ I 'll look ]
I find it curious the level control is before the first stage ,
as if it could overload ?

 

[PRR]

> a little noisy

Shouldn't be a problem _if_ you can use it right.

> level control is before the first stage , as if it could overload ?

Sure can.

Input to a mike preamp has a VERY wide signal range, and the preamp is expected to bring all sounds to about the same output level.

Dynamic on a soft talker may peak 1mV.

Big condenser on a guitar amp or drums can be 1 Volt or more.

So we need a range of gain near 1,000:1, and inputs as high as 1V.

I don't know the transformer specs, but a tube input iron will be 1:5 to 1:10. Say 1:7. So 1V at mike is 7V at secondary. If we do nothing else, V1a WILL overload.

This design uses one forward path with a NFB loop around it. Gain varies from 32 to 668. As long as the V2 stage can swing the implied signal, V1a won't overload. I would guess V2 can swing 20V. So the maximum level at V1a grid is 20V/32= 0.6V. Which is 0.06V at input transformer primary with pot full-up.

A funny thing: each stage IS adopted from Fender guitar amp. These values give a clean lightly-colored sound. If used that way, it might be interesting: Fender tone on mike amp. But when wrapped in NFB the color vanishes. More-or-less: at low gain it will be dead-clean, at high gain it will have half the color of a Fender at similar level.

And at higher input levels you MUST turn-down that pot. S/N is sacrificed but it should already be over 100dB by the time you run out of turn=down on the NFB gain switch.

If you don't use the gain-switch to the max (actually minimum), and turn-down at the pot, yes it can be noisy.

Even without the pot-loss, the 1K5 cathode resistor contributes some hiss. There's no clean way to cure that if low gains are needed with a mere tube or two for output.

If we follow the Fender-ripoff idea, the gain control goes between the first two stages. (And there should be a pad before the input transformer.)

It's a box with two irons and two 12A_7 sockets and power. The price was excellent. You ought to be able to do a mike-amp. Unless the construction is just too DIY-adverse.

 

[pH]

Interesting circuit, maybe a more flavorful Pultec MB1. Would be interested to compare your modded circuit the original schematic...

 

[thermionic]

I don't think we give John the credit he deserves. He's also holding down a successful career as a DJ: http://www.residentadvisor.net/dj/johnroberts

;D

 

[okgb]

Agreed re John Robert's one of the good contributors around here

Level control after the input [ where more people put them if they do at is before  ] xfmr
but before the first stage , which is not as common and in this case on a less successful product
[ yeah that could be more due to marketing and I think it was cheapness to be able to use a common
single gang pot ].  most often see pad beofre xfmr and level or gain after the first stage or a feedback type control
I imagine the pcb is straightforward enough to make cuts , but as it's not likely to be my main go to pre ,
I'll do the sensible thing and listen & live with it first before deciding on any mods .

 

[bigugly]

the schematic I posted is the mod. the original thread is here: http://www.groupdiy.com/index.php?topic=1121.0

I don't know what the original circuit looks like but I have TMP-1 I got new really cheap just to do the mod and then never got around to it. It's in a box somewhere in storage. Maybe it's time to dig it up.

 

[JohnRoberts]

I don't think we give John the credit he deserves. He's also holding down a successful career as a DJ: http://www.residentadvisor.net/dj/johnroberts

;D

Along with my presiding over the supreme court.... 8)

JR

 

[erikb1971]

and from that dj picture he also seems the spitting image of Ian Curtis! Let's dance to Joy Division!