Rick Holmstrom's amps?

[Sweetfinger]

Saw Holmstrom last friday. He had the best guitar tone I have EVER heard(and I have heard a LOT of great tones through the years). I pressed for some details after the show and the center of his rig is an old Valco made McKinney amp, undoubtedly made originally for lap steel. Has anybody out there got up close and personal with his amp, or another McKinney? Valco changed circuits like people change underwear. I'm just trying to home in on what other Valcos, if any, are identical circuits......or I'll buy one if somebody out there has one.

[Vintage47]

Sweetfinger Holmstrom Valco McKinney Amp

Saw Holmstrom last friday. He had the best guitar tone I have EVER heard(and I have heard a LOT of great tones through the years). I pressed for some details after the show and the center of his rig is an old Valco made McKinney amp, undoubtedly made originally for lap steel. Has anybody out there got up close and personal with his amp, or another McKinney? Valco changed circuits like people change underwear. I'm just trying to home in on what other Valcos, if any, are identical circuits......or I'll buy one if somebody out there has one.

I know this comes about 6 months to late but it maybe a help to clarify about Valco Amps. This is a lot from memory but I am looking at a pile of Valco schematic drawings and I own a few of them so most is pretty solid!

I am 99% sure (based on an article Holmstom wrote for Vintage Guitar about class A Valco's) the amp he used and that your asking about used the 'Supreme' layout it came in several models starting with Supreme 510. The 510-1B was used in amps built by Valco for the Mckinny, Supro Supreme, National Dobro (I have this one from 1947), and the lastest year was a 1950 Gretch, I am also pretty sure it was in some of the 1948-50 Bronsons. Valco was a sub contractor and they built and branded amps for anyone who placed a large enough order to make it worthwhile.

The tube layout is the 5y3 rectifier, 6Y7, 6SC7 to a pair of 6V6 and a 4 ohm 10" speaker (in 47 it was a field coil wound speaker), I have found this with 2 inst inputs and with 2 inst and a mic input, I have also seen this with and with out a tone control, The 1947 National I have is the very basic 2 input, 1 volume knob, class A with field coil 10" speaker.

The mic input and tone control came after 47 although the rest of the circuit remained the same 510-B in all other regards. Some of these were chassis rubber mounted to the bottom of cab, some midway up just above the speaker magnet. The rubber mounting helped reduce the microphonics associated with the 6SC7 preamps of the timesThe more stable 12**7GT came out in I think 1948 and changed all that, but it also changed the sound.

The biggest tone killer of all in these little jewels was guys changing the speakers out to 8 Ohm thinking they it was better or louder! The output tranny is wants a 4 Ohm load, which puts the sweet spot for the breakup distortion in the upper middle voume range, increase the the speaker resistance and you have to push it all the way to the get just a portion of the same tone! That doesn't work and in fact, works against you, if you want louder you mic the front of the box like the old timers did, these amps work best the way they were designed!

I think that Terry Dobson "Mr. Valco" is probably been working on these longer than anyone around and he will confirm what I said above but he can add a lot more detail about all the models and be more specific on the year models and changes. Terry will also tell you not to mess with the 4 ohm output!

As far as buying one with the 510-1B layout, you can watch ebay and the internet real closely, hit all the guitar shows in your area, and dig way down dep in your pocket, broken beaters going for 200+ and working condition $500-$700 common now days. They have actually been inflated in price to the point that I have now have patterned a few of the cabs and started bending the chassis for one off reproductions, I should have pics and details on my website by mid /late January.

Hope that helps clarify a bit?

[Vintage47]

More about the Valco Chicago 51

This is the most mis-used Valco Model name to the point that it has come to be an AKA, but it is actually the address suffix. Before the the 5 digit zip code system came into use we had a two digit address suffix system? If you remember this you are getting old!

I remember one of mine was Sacramento 25, Calif and our telephone prefix was Ivanhoe (which translated to I then V which were 4 then 8 on the rotory dial, or Wallbash which was w then b or 9 then 2) in real small communities all on the same profix you just dropped the prefix and dialed the last 5 numbers to reach you party. As the world got more crowded we needed more numbers to sort things out, as was the case for both phone and mail communications.

There appears to be a schematic for a model called the 'Chicago' but the 51 is part of the address, Valcos' address was;

Valco Mfg.Co.
400 S. Peoria St.
Chicago 51, Ill.

So when you see the number 51 after the Chicago on these, it could be made in 1948 or 1954, it could be Supro, Dickerson, Oahu or National and has nothing to with anything but delivery of mail!

So if you see a classified seller listing 'Chicago 51' as a model, assume he doesn't know much about Valco and he probably is just shooting hype to get the price up on the sale.

If you have a Valco amp, check the tubes and the components and cross reference it with schematics to find out what you really have, its not that hard with computer searches to find the different schematics. Most are found under Supro, Valco, National and early Gretch, some under Airline, McKinny, Oahu, and a few others I have forgotten, but those schematic searches bring up most of them. You'll evenually find a match, and it probably won't be a '51'

Hope that helps clarify the '51' model suffix?

[Sweetfinger]

Thanx!

The info comes a little late, but is good to have anyway. I actually found a McKinney like Rick's, or at least close enough. It has 6J7 (pentode) pre-amp tubes with the grid cap, and a Field coil speaker that is 8 ohms. The speaker got some paper damaged in shipping so needs a recone, but the amp works and with a little service, is gonna sound pretty good.

Holmstrom takes a line out into a larger amp like a Super Reverb, or lately, a recent Ampeg. For louder gigs, I'm going to adapt an old Operadio P.A. amp to work as a guitar head, as it also has the 6J7 pre-amp tubes with a bit more robust 2-6L6 output.
After the research I did, and with my own evolving appreciation for pentode pre's, I'm thinking that part of the magic is the pentodes, which will certainly give a different response than the triodes used later. If I ever get around to these things, I'll post results. I've been so busy that I haven't been able to get to the amp, but I think I have most of the pieces.....other than Rick's amazing talent and nutty, but oddly appropriate note choice.

[Vintage47]

when reconed let me know how it comes out!

Sorry about the speaker damage, I have a nice 47 10 incher with the field coil and been wanting to get it reconed but not sure who to trust to do it original, lots of reconers out there but not all equal in old vintage. When you get yours done, and if it comes out soundin' good and original, could you post a recommendation and contact link.

Terry (mr valco) recommends Weber but they seem a bit pricey, hoping to find another to save a few bucks. I had a great guy over in Sacramento that reconed for me since the early seventies, really new the old stuff, but he retired! Contacted a guy in PA who was highly recommended old timer but he says he is not taking any new work until he gets caught up sometime next year.

There is a great book out by Richard Kuehnel called Guitar Amplifier Preamps, a little heavy on math formulas, but he makes a pretty good case for "it's all in the preamp'. He shows the essentials to creating a stand out different signature sound is all in the first stages, after that it is just making whatever you start with louder. The 6Y7 definatively contributes a blues signature tone all it's own!

I have been temped to try one of the porcelin top caps in place of the metal top cap shield that was original 6Y7, Have you tried one of those type caps? Any info on those would be appreciated.

[Sweetfinger]

I have been temped to try one of the porcelin top caps in place of the metal top cap shield that was original 6Y7, Have you tried one of those type caps? Any info on those would be appreciated.

You mean 6J7, as the 6Y7(in your reply) is an archaic dual triode power tube. Though the 6J7's in my two amps are the first experience I've had with top cap grid tubes, I don't think I'd want to use any of the porcelain connectors because they don't look like they'll fit under the metal shield cap, which is there to keep down noise. I believe the porcelain caps are more appropriate for tubes with plate caps, or where noise would not be as much of an issue, like a non audio application.

[pila]

In regard to the 6J7 in Valco designed amps, I've been using a 6SJ7 instead on the clones I build. No grid cap (and the shielding) to deal with. 6SJ7 is a more modern design in it's time, with the same characteristics.
My favorite is the 510b circuit, although I've built a couple 6150 single end types.

[Sweetfinger]

I'm going to adapt an old Operadio P.A. amp to work as a guitar head, as it also has the 6J7 pre-amp tubes with a bit more robust 2-6L6 output.

A little update here:
I opened up the Operadio PA amp(which is a chore in itself). Of course, all electrolytic caps got changed. Also found a leaky PI cap. Several of the pots were frozen and needed a lot of lubrication and fidgeting to get going again.

The design dumped a lot of power by using a voltage divider on the 6L6 screens. I moved some power supply values a little closer to Tweed Pro territory and reworked the Phono input a little.
Result:
The stock tone stack is voiced pretty weird, very difficult to get a sound that I like. Reminds me of things that I don't like about AC-30 tone stacks. I will likely redo the tone stack to a blackface circuit. The phono input/channel does not go through the tone stack, so is pretty much uncolored. Sounds pretty good! The amp is quite loud and gets really distorted in the way that I had hoped.

I still haven't got my field coil speaker reconed. anybody have news on reconing since this thread started?

[pila]

speaker reconing

There is a place in Lima Ohio called "The Speaker Shop" that does field coil speaker reconing I'm told . Haven't tried them my self yet.
Their phone is (330) 758-6911

PILA