Found an Old Mono Hoffman Record Player with 5E3 configuration

[Platefire]

Stopped off at a Pawn Shop the other day I found an old vintage Hoffman mono record player. Looking on the back it has a tube chart 2-6V6's, two 12AX7's and a 5Y3. They had it marked $25.00. Had a nice wood case. Don't know if it would be a good idea to gut it for a guitar amp since I got plenty and in the process of building a brand new 5E3. It may be better purposed to remain a record player. Kind of tempting though? Plate  

[eleventeen]

Well, I look at it this way: The 2 qty 12AX7s are worth about $10 each, as are the 6V6's. So your risk is exceptionally low. Cut those numbers in half, you still aren't out much money relative to the value that you KNOW is there.

I bought a huge sweep generator today for $25 with 5 qty 6C10's, 2 qty 6BQ5/EL84, and 2 qty EL34, and of course the attendant knobs, huge power transformer. loads of switches, Fender-style pilot light ass'y. The 6C10's go for over $30 used on ebay, the EL-34s go for about $10 each and the 6BQ5's are about $5 each, used. So why am I supposed to overthink this? I also bought a DC voltmeter for $15 with 2 qty Mullard 12AX7's in it.

[rafe]

  That may have been Doug's kindergarten show and tell science project?

[Willabe]

That may have been Doug's kindergarten show and tell science project?

 

[Platefire]

I will go by and offer them $10 and if they say $15 and I say make it $12.50, them I'll know it was ment to be! 

[Slimtim]

does it work?because with that tube set,in a nice wood case and the guitar amp potential it seems a no brainer that it is worth $25 to me.if it powered up and played i wouldn't bother even trying to lowball it and just go straight for the wallet and pay them.

[Platefire]

Your right on all counts! There was a time I wouldn't have let the sun go down until I got it. Makes me wonder if I haven't turned a corner as it is tempting but I'm not as excited about it as I use to be. When you got conversions sitting in the closet that only get fired up occationally, it don't make sense to do another one.

I'll let it sit around a little longer and if someone don't get it, I'll gobble it up!    I let the other guy have a chance at it first. I guess I'll always be doing another project rather I need it or not. BTW, how many amps do you need, "Just one more". Plate    

[Platefire]

Well I did buy the record player today. It would not turn on in the shop and I made a low offer that was rejected, so I walked the first time and went ahead and did my shopping at wally world. Got to thinking in wally world that the turn table wasn't turning and decided it must be a incoming AC issue and the PT was probably good. On the way back home I stopped by the pawn shop and paid his price--$25. Got it home and sure enough, found a bad AC power switch. Pulled the chassis out of the cab. Turned it on briefly using a jumper on the AC and it was humming like crazy through the speaker but the PT and OT is working.

It has got the same tube configuration as a 5E3--so that may be the direction I go?? Platefire

[DummyLoad]

It has got the same tube configuration as a 5E3--so that may be the direction I go?? Platefire

can't go wrong there...it's a starting point anyway. you can mod till you're hearts content down the road. maybe even try the as-is ckt. first, of course after safety AC input and cap job?

don't forget; if you don't have a schematic, then reverse engineer at least the PS and output stage. document PT & OT wire colors etc. better still take lots of hi-res pics as well.

respectfully,

--pete

[PRR]

> reverse engineer at least the PS and output stage. document PT & OT wire colors etc

+1.

> Hoffman mono record player. ...2-6V6's, two 12AX7's and a 5Y3

Pictures? Model number?

RadioMuseum.org has a bunch of Hoffmans but no record-player with that tube line-up. It would be good to update their collection.

B807 is similar except 7189 power bottles and a EZ81 at the end.

This Hoffman was in Los Angeles through the 1950s. I *may* have had a Hoffman TV set and watched Bozo before he went national and franchised himself. Or Hoffman record-player to play Little Black Sambo. (This was a long time ago.)

[Platefire]

PRR--I have really put out a good effort to find some info on this record player without any success. I did go to the radiomusium and looked at the models they had listed but no luck.
Judging from the case, it looks late 40's or early 50's but it does have 12AX7's---so I don't know exactly when they came into use? The model number in hand written, was scribbled and faded out almost impossible to read--closest I could make out M N401. It's a larger portable table top type unit pretty heavy to move around for one person. Also has a Hoffman turntable that gets it's power from the amp. The tubes are Hoffman also. I never heard of Hoffman before but it looks like they use to be pretty big once. It has no normal type fuse that I can tell so I suppose the circuit was un-protected??? I can take some pix of the cab if someone is interested but here is some pixs of the pulled chassis. Plate

BTW-The face plate(last pix below) is what the treble, volume and bass control shafts went through. The easy vision is refering to those red dials you see on the pot shafts that you view throgh the two windows on the face plate.

[Platefire]

This is some pixs of the Record Player cab. PRR was trying to help me identify the model. In all my searching Hoffman stuff haven't found this model. I did re-look at the model number as I was taking pictures in the sunlight and the writting looked a little clearer-appears to be =M W401. I would love to obtain a shcematic of the existing circuit. I wish I could utilize the existing cabinet to convert into a guitar cab for the amp but I've looked it over and I don't see a way. Plate

[Platefire]

Kinda disappointed. Fired up the little amp to check top loaded voltage=259DCV to the first power rail resistor. That is really low!

Another weird arrangment is there is an extra yellow wire coming from the OT tied into the screens Through resistors. Kind of reminds me of ultra-liner OT arrangment I've seen before.

I hooked a guitar up to it today through the RCA connection where the turntable plugs in and managed to get very low volume amplification. So with the low voltage, don't know what kind of guitar sound I would be able to deliver even if I rebuild the circuit? So I might be better off to just sell it on e-bay than putting a lot of time and money in it. Any suggestions? Plate

[DummyLoad]

plate - low B+ indicates that it probably is in need of new power supply filter caps.

maybe it is UL?

--pete

[Slimtim]

i bet this is part of an entertainment center.easy vision was their tv sets name.named so for the special glass on the set and was only a hoffman thing.with the amp in the cab where does the power wire come into the cab?i ask because that mesh over the hole in the back does not look original to that nice cab.and do both of those brown leads out the back of the amp hook to the turntable?i read 1 comment made about a hoffman tuner running 6v6 pp and they said it was the best a.m. they ever heard.and it was part of a console unit.the stand alone hoffman turntables i saw looked no where near this nice.those all looked like bedroom units for the kids.this looks like it went in the living room to match the furniture.search for the easy vision console or entertainment type centers.they made a bunch.and you'll see what i saw.

[Slimtim]

does anyone beleive that unit originally came with that 4"speaker and running 2 6v6gt.no way, .i think that whole front piece has been redone or someone added that speaker when they seperated this cab from a larger unit.but i've looked at hoffman units large and small and none look like that front.and i didn't see any record players that had a single speaker that small.i also found very few hoffman products running a 5y3gt rec on 6v6 tubes and when they were together they were not with 2 12ax7.

[Platefire]

The unit seems to be self contained and completely independant. I have cut off speakers from console units before and this cab hasn't been seperated in that way. The power cord goes straight to the amp. The turntable has a normal two prong AC plug that plugged into the amp chassis where you see the female plug on the chassis for it's power. Also a RCA male plug attaches to the RCA female jack in the chassis. Very simple setup. Plate

[PRR]

All old home-type 6V6 amps ran around 250V-300V. In cathode-bias a higher voltage does not mean more power. Fender's fix-bias 6V6 amps were much too brave for 1953.

It should be a fine guitar amp, when it is fixed. Much can go bad in 60 years.

All the wax-caps should be PRESUMED bad. The hard-case caps are dubious.

With that construction, it may (sad to say) make sense to torch-out everything, and build a DeLuxe etc on the sockets.

I do agree that a 10-Watt amp doesn't go with a single 4-inch cone. Other Hoffmans in this power range seem to have several 8" as well as a 4" tweet or two.

12AX7 introduced 25.Sep.1947.

Hoffman radios were two chassis: tuna and audio-amp. The 1958 radio used amp chassis 1108. I suspect that chassis 1100 is much older (makes sense from the tubes).

I'm thinking that Hoffman was a lot about custom "furniture". I was in LA in that period and the cabinet makers were strong. (WWII needed a lot of small wood parts so a lot of small shops acquired state of the art woodworking machinery and thrived through the 1950s.) The electronics are good but nothing special. I suspect that "models" were often short-run, even one-off (hence the write-in on the label). And probably all factory records were trashed when the operation closed. So we may never know what a "M N401?" was. And since what you have seems under-speakered, it may only be part of a complete unit.

As SlimTim says, Easy Vision was a TV model. As SlimTim suggests, I can picture this, on top of a TV, with some larger speakers under the TV chassis. The big cones way low would not couple back to the needle and cause turntable feedback. The Four up top would raise and center the dialog for excellent sight/sound integration.

[Platefire]

I don't know where SlimTim got his speaker info, but what actually exist is about a 8" to 10" elliptical shaped speaker and a smaller approx. 4" speaker both joined together by a small circuit. I measured the ohms and it was 4 ohms load, so I guess that is what the OT would be. So it would be capable of producing a pretty decent sound.

I agree that gutting it would be best policy leaving tube sockets and transformers. In reference to the attached gut shot pix of chassis my offhand general idea is:

1-Install a 1/4" jack and a fender tweed tone stack in the area of the RCA jack. This side of chassis would be the face.

2-On the oppisite end of face by the rectifier would be the pilot light, power and standby switch.

3-On the opposite end(back) of chassis from pilot light would be the power cord and fuse.

4-In the open space under PT install Illionios(small) filter caps on terminal strips along with power rail reistors. The terminal strips could attach to PT bolts.

5-Of course I would need to install a speaker jack on back side about in middle to line up with OT wire hole in chssis.

6-Also thinking it may be a good idea to buy a new 8 Ohm OT to make it match more modern day speakers or my existing 8 Ohm speakers. I don't think I have a single 4 Ohm speaker!

Does this sound like an OK plan? Plate

[PRR]

me> I'm thinking that Hoffman was a lot about...

I was so wrong. Hoffman was a major player in many fields of electronics, as well as a shrewd businessman, also philanthropist.

http://www.tvhistory.tv/1950-59-HOFFMAN.htm

http://en.wikipedia.org/wiki/Les_Hoffman

[Platefire]

Hoffman must have been on the higher end because in the small Louisiana town I was raised in it was RCA, Philco, Zenth, General Electric most of the time portable sets on a seperate stand. Very few people I knew had console TV units. Very few people had hi-fi console radio/player units. Most people had small portable suit-case type record players. I only became aware of Hoffman's existance through this record player. Plate

[Slimtim]

Sounds like a plan to me.Plate did you say that unit has 2 speakers in it?i only saw the 4" is why i said that.Also if the turntable plugs into the female plug on the back of the amp and one of the brown cords goes to the wall,what does the other brown cord goto?And why is one side of one of those brown cords hooked straight to the rec. tube?Sorry if it they're a simple obvious answers i'm a noob and learning as i go.

[Platefire]

Hi SlimTim

You've got a very good eye for detail. I went back and looked at the pixs I posted but didn't see where any shows a speaker. Where do you see a speaker???

Good question on the brown AC wire going to the rectifier tube! Normally the AC would have one leg going through a fuse but this amp doesn't have a fuse. I've never seen this kind of hookup before! OK here goes:

1-The two black primarys from power transformer(PT)that normally goes to the AC power cord. Proper connection on a guitar amp is white goes directly to one PT black and the other power cord black goes through fuse, then power switch to the other PT black. Nowdays you would also have the power cord green that would go to chassis ground but this was before that standard came along. Well on this amp the two power transformer blacks goes to the two legs/terminals of the female AC plug in the chassis.

2-The power cord for the amp goes trough the strain relief with one leg going to one terminal of the AC plug where one of the PT primary blacks is attached. The other leg of the power cord goes to pin #7 that is a "No Connection" (NC) on the 5Y3 rectifer. That connection has no effect on the rectifier and they are just using it for an extra AC connection terminal.

3-The extra brown cord you was asking about is an AC power switch. The switch end mounts through a hole in the board that the turn table mounts in. So one leg of the switch goes to the NC pin #7 on rectifier and the other leg goes to the other terminal on the AC Plug.

4-With that setup, when you turn on the power switch on it not only provides AC power to power transformer (turns the amp on)but also provide AC power through the AC plug to turn table.

5-Couple of things strange about the record player is it had no fuse in the amp and had no pilot light to let you know it was on or if it ever had an "on" light, it is now missing. The turntable is very heavy duty contruction like most stuff in those days. I might try to e-bay that, someone might be looking for one. Plate


good eye SlimTim

[Slimtim]

i assumed that is a speaker hole on the front behind the cloth and what i thought to be a baffle.so where are the speakers located on this unit,in the rear?no fuse,weird.heck yeah pull the amp for yourself and ebay or craigslist the cab and/or turntable i get your money back .i read somewhere that hoffman used garrard turntables on some units at one point.

[Platefire]

SlimTim

Check the previous pictures. You posted before I could get the pixs posted. They are behind the grillcloth, just not as you suspected. Plate

[PRR]

> Where do you see a speaker???

This picture:


-shows a ~~4" shadow top-center of grill-cloth. That's just what old grills look like after children poke the cloth a lot.

Your later picture shows that hole, but bridged with the tweeter/woofer crossover board, and the two speakers on either side. The extra hole hints that Hoffman had some precut speaker boards which were re-purposed for this specific model.

My family had an RCA console, only because my dad worked there and got a discount. It was a cheaply made "nice" cabinet with semi-junk electronics. (Probably Mullard 6BQ5/EL84, but they were commonplace.) Otherwise we had a dad-made box with RCA turntable and hot-chassis amplifer, no knobs.

[Slimtim]

wow i would never have guessed the speakerS were configured that way just from looking at the front.

[Platefire]

In the late 70's my parents bought a console unit FM/Am/Stereo Record Player that I enjoyed when I went by there. By then I was married with two kids and been out of the house 10 years. I had bought a Radio Shack portable stereo with fold out turn table and FM/AM with detachable speakers. That unit served me well as we did a lot of moving around in those days. The Hoffman would have been a welcomed upgrade in the days I was copying all those Venture licks in the 60's.

So I guess my next step is gut all these old components out of the chassis. Some big blobs of solder and tough mechanical connections to break down---but I've been down this road before. Plate

[John]

Hey Plate, just because I know you got nuthin' better to do,  you should send some of those pics to the website PRR linked to. They're looking for more pics. I'm thinking your goodie might be listed there under the M1041 ? It says a 21" table top. 

[Slimtim]

thats a tv

[PRR]

> pics to the website

1) He should be a member to donate pix. (Also they like better pictures, which can be real work.)

2) RadioMuseum.org's listings for Hoffman are incomplete and mixed-up. Schematics for "record player" turn out to go to AM/FM radio schematics. I've pointed this out, and gotten no response. It's pretty quiet over there.

If Platefire had a known complete set and clear model-number, and interest at RM.org, it would be nice to add it to the collection. The way it sits with a ?? model scribble, eh.

[Platefire]

Yeah, if they don't care enough to keep their site up and correct information when it's brought to their attention, I don't think I want to invest time trying to make them do it. On the other hand if they were really interested, I would re-assemble enough of the orginal parts back in the cab to make it look original and take some prictures with the face plate and knobs installed.

I stripped/gutted the amp chassis last night. I even pulled the nine pin sockets out because they were so delicate they were coming apart just trying do desolder the leads. I also removed the can caps and main power rail resister that was mounted vertical like the can caps. The chassis is now so full of holes it looks like the swiss cheese    Plate

[Slimtim]

so were you going to try and use the cabinet or sell it off?

[Willabe]

thats a tv

I'm having a problem tuning in Gilligan's Island.


             Brad     

[Platefire]

Got an OT Question and please look at attached pdf. I was looking through my tube stuff for a workable 8 Ohm OT. This Hoffman amp has a 4 Ohm OT and I was wanting 8 ohm OT. The only thing I could find with possibility is from a Hammond PR-40 Organ amp that has three amps built in one chassis, all PP EL84's on each amp. One amp is treble, one amp is Reverb/treble and the other is bass. The two treble amps have 8 ohm OT but have extra UL connections or different additional hookup wires than the norm.

My question is On the Hammond 8 Ohm OT, if I used just the primarys for main red for DCV, power tube plate wires for my pp 6V6's and secondarys for 8 Ohm speaker and just didn't use those UL leads, would this function like a regular OT in a way that would be desirable? Platefire

[sluckey]

My question is On the Hammond 8 Ohm OT, if I used just the primarys for main red for DCV, power tube plate wires for my pp 6V6's and secondarys for 8 Ohm speaker and just didn't use those UL leads, would this function like a regular OT in a way that would be desirable?

Those extra wires are not for U/L operation. They are for negative feedback (NFB). Just tape them off. Either of those treble amp OTs will work fine in your 6V6 build.

That original OT on your chassis is very light weight for a guitar amp. But it's probably a good match with the PT for a small low power record player. I'd use it especially if you're gonna build an amp on that same chassis. I would not worry about using that 4Ω OT with an 8Ω speaker.

Which circuit have you decided on?

[Platefire]

I haven't decided yet. I was thinking normal fender input with first stage preamp with cathod 25uf/25V cap and 1500 res. I'm still deciding on tone stack. I know tweed stacks allows more gain
and I was wondering how much the treble/bass stack that you used effects gain. Pretty much thinking 5E3 PI & power section. This is pretty standard stuff and wondering if I should search for a different direction. With the low PT voltage, I'm not sure I should get to adventurous   Open for suggestions since you know what I'm working with.

I was really wanting to use that extra V1 preamp stage as a hot switch stage and installing a master volume but if it is distorted at higher volumes because of the low voltage all that might be useless.

BTW-I might try it with original OT first, I can always change it latter.

[Platefire]

Wow! Talking about amp manufacturers having parts around a long time before using them! I just checked the transformer codes:

PT=606405   606=Schumacher brand   40=1940   5=5th week of 1940

OT-606411    606=Schumacher brand   41=1941    1=1st week of 1941


PRR said 12AX7's didn't come out until 1947, so since this amp has 12AX7's, it had to manufactured sometime after 1947. So these transformers sat around 7 years before use.

    

[Willabe]

They might have got a deal on someone else's surplus.


              Brad   

[PRR]

If the original iron works, use it.

It has all those old electrons in it!!

This is two-6V6, right? So it comes out 8 Watts instead of 12W like the p-p Gibson or the 21W of a goosed Fender. Any way you do it, it's too small for stadiums, too big for bedroom, so 8-12-21 Watts is all about the same.

And at 8-10W that OT is big enuff for big fun. With 6" or 8" speakers you won't have deep bass anyway. (If you propose to run two-12", my advice might change.)

Assume Hoffman's designer knew what he was doing.

Likewise I wouldn't fret about a few more/less Ohms.

> these transformers sat around 7 years before use.

Interesting but reasonable. The PT was a pretty stock item for many large radios, and there may have been large inventories. The OT is also common. 1941 started "normal" but by the end of 1941 it was clear the US was going to war. Early 1942 most civilian production stopped, ALL car-companies and radio-makers stood-by for military orders. Any inventory on hand was pushed to the back. While that PT and OT could have been used for some military rig, the contracts specified WHAT parts to use and since it was Uncle Sam's money, he got what he ordered. After the war ended, it took a while for the economy to start-up again. Also there was fear of price-gouging on items in short supply, so the government imposed Price Freezes. These were so draconian that Ford almost quit the car racket and Tucker saw his loophole.

And we can suspect that Hoffman was not making a lot of deluxe record-players. A two-6V6 rig would be a hotel or school, not a home. Also the hand-scratch model number. And we know Hoffman was a sharp buyer (using surplus plane-canopy plastic for TV screens). So he found this iron in the back room, and used it.

[sluckey]

PT=606405   606=Schumacher brand   40=1940   5=5th week of 1940

OT-606411    606=Schumacher brand   41=1941    1=1st week of 1941

I believe those codes break down like this...

PT=606405   606=Schumacher brand   4=1954 (last digit of year, 0 through 9)   05=5th week (week of the year, 01 through 52)

OT-606411    606=Schumacher brand   4=1954 (last digit of year, 0 through 9)    11=11th week (week of the year, 01 through 52)

[Platefire]

Well this site is where I got my dating info. So I was going by the way they said to read the code. I may have read it wrong.

http://ampwares.com/faq/how-old-is-my-vintage-amplifier/

In the right hand column on the link is where they explain how to read it.

XXXYYZZ=according to Ampwares XXX is the manufacturer, YY is the year and ZZ is the week(1-52)  I haven't had much experiance reading transforer or pot codes, I just got curious and did a search and this is what I turned up. Don't really care, was just shocked when 40 matched the year space. So what ever it turns out to be is OK. Plate  

[sluckey]

That's the same site I used. Here's a quote...

EIA Source-Date Codes: Electronic components such as transformers, potentiometers, speakers, and some capacitors are often stampted with a date code indicating who manufactured them and when. The code follows the format: XXXYY ZZ where:
 XXX = a two or three (possibly four on newer amps) digit number indicating the manufacturer. (see chart below)
 YY = is a one or two digit code indicating the year. If it’s a one digit year you need to determine the correct decade of the amp some other way.
 ZZ = a number from 1 – 52 indicating the week of the year.

You have a six digit number so the code is XXX Y ZZ. Read the red sentence above. You only have one digit for the year and you have to guess the decade. You will always have two digits for the week so you can represent 1 thru 52.

[Platefire]

Well thanks Sluckey

That makes more sense to me because even though the 12AX7 was released in 1947, how many amps did you see using them right off the bat. Even Leo took a while to warm up to a 12AX7. Plate

[Willabe]

That makes more sense to me because even though the 12AX7 was released in 1947, how many amps did you see using them right off the bat. Even Leo took a while to warm up to a 12AX7.

Amp makers might have needed a little time to be convinced of the new tubes reliability? Plus they would have to re-engineer the circuits. PT's would be changed also at some point to save money because the new 9 pin tubes used less heater voltage than the octals.


               Brad     

[Platefire]

Yeah I got a couple of amps with the old 6SC7 V1 that sounds pretty good to my ears. One significant historical note!!!! I and the 12AX7 was both born in 1947 and we're both still going strong, Thank the Lord! The 12AX7 became a little bit more popular than me over the years, but we are still good friends   Platefire

[Willabe]

I and the 12AX7 was both born in 1947 and we're both still going strong, Thank the Lord!

Yes!     

The 12AX7 became a little bit more popular than me over the years

That's good, your wife might not like it if you where as popular as a 12AX7.


               Brad     

[Platefire]

Well enough insanity!  

Meanwhile back at the ranch-- Took some pictures. Got the chassis stripped out and fitted in some new 9 pin sockets, some switches and a pot. I found some really cool crome metal hole plugs at LOWES=1/2", 3/4", 1 1/8" & 1 1/4" to go where I pulled out the old can caps, power resistor and where the external pot wires went through. Lot easier than cutting special hole cover plates, drilling holes for screws and the plugs look really clean.

I just haven't decided rather to use that large 1 1/4" hole to mount an new 20/20/20 can or mount regular axle caps on a two terminal strips using the transformer bolts to mount. The can would be a lot cleaner and leave more room in the chassis. I'm leaning toward the can but need to do a little research on size in mounting it in the hole. Plate

BTW--these conversions really make you think!! especially when you got limited space. You have to get really creative to make everything fit and work. I really haven't got room for a two knob tone stack unless I let the tranformers be in the front---I like transformers in the back--tubes in the front!  

[Willabe]

Looking good.


            Brad     

[Platefire]

Well Thanks! I'll do something even if it's wrong and then modifiy it to correct it. 

Plate-a-Fire